Boule of the iii-v groups element nitride used for production of substrates and the method of its manufacture and application
FIELD: semiconductor technology; production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules.
SUBSTANCE: the invention is pertaining to production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules and may be used in semiconductor engineering. Substance of the invention: the boule of III-V groups chemical element nitride may be manufactured by growing of the material of III-V groups the chemical element nitride on the corresponding crystal seed out of the same material of nitride of the chemical element of III-V of group by epitaxy from the vapor phase at the speed of the growth exceeding 20 micrometers per hour. The boule has the quality suitable for manufacture of microelectronic devices, its diameter makes more than 1 centimeter, the length exceeds 1 millimeter, defects density on the boule upper surface is less than 107 defects·cm-2.
EFFECT: the invention ensures manufacture of the microelectronic devices of good quality and above indicated parameters.
102 cl, 9 dwg
This invention was made in pursuance of contracts BMDO # DNA001-95-C-0155, DARPA #DAAL01-96-C-0049 and DARPA # DAAL01-98-C-0071. The government has certain rights in this invention.
This invention relates to a bule to the substrate of the nitride of the element III-V groups and the method of its production and use, and records obtained from such boules, and microelectronic devices and structures-the predecessors of such devices, manufactured on such records and/or in them.
The current lack of high-quality substrates from nitrides of elements of the III-V groups for the subsequent deposition of nitride epitaxial layers limits the performance and slows down the necessary and desired development of short-wavelength optoelectronics and high frequency electronic devices high power.
For example, the present approach growing heteroepitaxial nitride epitaxial layers on foreign substrates such as sapphire, has an adverse effect on the quality of the final material and the functional capacity of the device for the following reasons:
(1) the mismatch of the crystal lattice of the layer that provides the devices and the substrate leads to a high density of defects, which impair its characteristics;
(2) nesiotes is their temperature coefficients of expansion between the layer provides the devices and the substrate leads to the appearance of the layer, provides the devices, stresses, cracking and defects that weaken voltage;
(3) insulating substrates require lateral (transverse) the geometry of the device, which can slow the flow of current through the device (this problem is reduced, but not eliminated for devices grown on conductive substrates, such as SiC, where, however, there is still a barrier voltage between the layer provides the devices and the substrate);
(4) the creation of an electrical contact over a large area with a layer that provides the device is p-type, is more complex because of the lateral geometry of the device, defined by the substrate;
(5) the heat dissipation from the device is limited by the low thermal conductivity insulating substrates such as sapphire;
(6) electrical characteristics foreign substrates are difficult to modify for specific applications of the device, for example, doped substrates of the p-type back light-emitting diode (LED) or laser diodes (LD) or polisilicon substrates for electronic devices;
(7) the ability of the splitting of the (Al, Ga, ln)N on foreign substrates is complicated by the mismatch cleavage planes between the epitaxial film and the foreign substrate; and
(8)it is difficult to get in epitaxial films or layers of the device, the orientation of the crystals, other than C-plane, resulting in not implemented improved material characteristics and/or device for such alternative orientations.
Efforts to obtain the bulls for homogeneous nitride substrates by conventional methods, volume growth was not successful because of a number of fundamental characteristics of nitrides of elements of the III-V groups. First of all, the equilibrium vapor pressure of nitrogen over these compounds at moderate temperatures is extremely high. Nitrides of elements of the III-V groups begin to decompose at temperatures below their melting temperature, making it extremely difficult to customary methods of volume growth. In addition, the nitrides of elements of the III-V groups have low solubility in acids, bases and other inorganic compounds. The combination of these characteristics of the material complicates the manufacture of the substrate of the nitrides of elements of the III-V groups.
However, an attempt was made to conduct a large growing material nitrides of elements of the III-V groups using methods sublimation and growth from solution (see, for example, G.A.SIack, T.F.McNelly, J. Cryst. Growth, 34, 263 (1974); J.O.HurnI, G.S.Layne, US patent No. 3607014; P.Chen, Final Report, Contract NASW-4981, (1995); P.M.Dryburgh, The Ninth International Conf. on Cryst. Growth, ICCG-9 (1989)), as well as methods of evaporation/reaction (see J.Pastrnak, L.Roskovcova, Phys. Stat. Sol., 7, 331, (1964)). Slack and McNelly (G.A.SIack, T.F. McNelly, J. Cryst. Growth, 34, 263 (1974)), PR is changed method of sublimation at temperatures of about 2250° To obtain crystals AIN small size (diameter 3 mm and length 10 mm). Rojio et al., Materials Research Society, December, 1999, the Obtaining and characterization of substrates of monocrystalline aluminum nitride" ("Preparation and Characterization of Single Crystal Aluminum Nitride Substrates") report of boules from aluminum nitride with a diameter of 1 cm and about how to obtain a substrate of single-crystal AIN of the a - and C-faces using mechanochemical polishing to achieve surfaces that are smooth at the atomic level, for the deposition of epitaxial layers AIN and AIGaN way OMVPE (epitaxial growth from the vapor phase ORGANOMETALLIC compounds). Ivantsov and other Material Research Society, 1999, "GaN Ingots with a diameter of 20 mm, grown from a molten solution with application method seed" ("GaN 20 mm Diameter Ingots Grown From Melt-Solution by Seeded Technique") describe the formation of GaN ingots, having a volume of 4.5 cm3grown from a molten solution with the method of the seed at temperatures of 900-1000°at pressures below 2 MPa and the growth rate of 2 mm per hour to obtain substrates used for homoepitaxial GaN. In U.S. patent 5770887 (Tadamoto) described the formation of single-crystal nitride-based material having a width (width at half height) of the line spectrum of x-ray diffraction 5-250 and with a thickness of at least 80 μm, the oxide buffer layers that enable the Department shall be separate etching plate; however, the resulting substrate plates have a limited area due to the need to carry out etching in the lateral direction through the oxide buffer layer to effect the separation.
Similarly the size of the bulk GaN material is limited by thermal instability of GaN at high temperatures and limited solubility of N in molten Ga. High equilibrium pressure of nitrogen above the GaN does not allow its cultivation without apparatus, designed for extremely high pressure (see J.Karpinski, Jum J. and S. Porowski, J. Cryst. Growth 66 (1984)). The low solubility of N in Ga, and it ˜ 10-5M at 950°makes it possible to successfully grow GaN from solution (W.A.Tiller et al., Final Report, "Investigation of the possibilities for growing bulk single crystal GaN" ("A feasibility study on the growth of bulk GaN single crystal"), Stanford U., July (1980)). The transition to an economically viable method of growing from solution at high pressure (2×104ATM) gave a very small crystals is less than 70 mm2area, which grew with the speed of only 20 µm/h
Electrical characteristics of bulk GaN material obtained in the usual way, is also limited to the high background concentration of carriers in this material. The concentration of electrons in randomly doped GaN films grown from solution at high pressure, which leaves more than 1× 1019cm-3(S.Porowski J. Cryst. Growth, 189/190 (1998) 153) and does not allow for controlled doping of this material for use in specific devices.
The lack of large high-quality seed crystals for the system (Al, Ga, ln)N led to the development of bezzatratnyh methods of cultivation, as described above. A small number of works by growing GaN from seed are usually conducted on sapphire (see, for example, D.EIwell and M.EIwell, Prog. Cryst. Growth and Charact, 17, 53 (1988)) or SiC (see S. Wetzel, D.Volm, B.K.Meyer et al., Appl. Phys. Lett., 65, 1033 (1994); and C.M.Balkas, Z.Sitar, T.Zheleva et al., Mat.Res.Soc.Proc., 449, 41 (1997)) because of the absence of nucleating nitride. For three-dimensional growth on foreign seeds have the same problems associated with the mismatch of the lattices and the coefficient of thermal expansion, as for the nitride heteroepitaxy on foreign substrates. Cracking of the nitride during bulk growth and cooled to room temperature negates the advantages of foreign seed. Reported high speed growth, such as 300 μm/h (C.Wetzel, D. Volm, B.K.Meyer et al., Appl.Phys. Lett., 65, 1033 (1994)) for GaN crystals obtained by the method of layer-by-layer sublimation. However, the total thickness of the obtained GaN was only 60 microns due to the use of non nitride seed that led to significant cracking.
Monocrystalline plates of material GaN were recently is obtained by growing a thick GaN films on foreign substrates, which was removed after growing by heating (M.K.Kelly, O.Ambacher, R.Dmitrov, H.Angerer, R.Handschuh and M.Stutzmann, Mat. Res. Soc. Symp. Proc. 482 (1998) 973), chemical etching (wet/dry etching) of the substrate and the interlayer materials (T.Detchprohm, K.Hiramatsu, H.Amano and I.Akasaki, Appl. Phys. Lett. 61 (1992) 2688; Y.Melnik, A.Nikolaev, I.Nikitina, K.Vassilevski, V.Dimitriev, Mat. Res. Soc. Symp. Proc. 482 (1998) 269) or physical destruction of the sacrificial substrate or intermediate layers (S.Nakamura, M.Senoh, S.Nagahama, N. Iwasa, T.Yamada, T.Matsushita, H.Kiyoku, Y.Sugimoto, T.Kozaki, H.Umemoto, M.Sano and K.Chocho, Jpn. J. Appl. Phys. 37, L309 (1998)). The cost of such vysokoenergoemkikh ways slows down their widespread use in the manufacture of plates.
Accordingly, a significant step forward in this area would be getting improved substrate from nitrides of elements of the III-V groups for the manufacture of microelectronic devices.
This invention solves the problems and overcomes the limitations of existing methods by growing bulls (ingots) nitrides of elements of the III-V groups of the vapor phase in homogeneous composition nitride seed.
In this context, the term "nitride III-V group" refers to a semiconductor material from compounds of elements of the III-V groups, including nitrogen.
Boules according to this invention have dimensions that give the possibility to divide them, for example by sawing, cutting or other method of division into parts, p is establisha a substrate in the form of plates, which are large enough they can be placed microelectronic device or structure precursor of microelectronic devices. The material of the bulls has a degree of crystallinity that is suitable for the manufacture of such a device or structure, the predecessor of such devices, that is, crystallinity, as appropriate for the device.
In one aspect this invention relates to a bule nitride of an element of group III-V grown using homogeneous with her crystal seed and having a diameter greater than 1 cm and a length of more than 1 millimeter, which is essentially free from cracks and has a density of defects on the top surface of less than 107defects per cm2.
More preferably the diameter or lateral dimension of the bulls is more than 2.5 centimeters, and most preferably, this width is more than 7.5 cm; length (the thickness of boules in the direction of growth) more preferably is more than 0.5 centimeter, most preferably more than 1 centimeter. Quality crystal boules, as a rule, is that on the x-ray double swing crystal the value of the half width of the line maximum is less than 600 arc seconds, more preferably less than 250 arc seconds. More preferably the density of the surface of defectos bule is less than 10 4defects per cm2.
In another aspect this invention relates to a bule nitride of an element of the III-V group, having a density of defects on the top surface of less than 105defects per cm2diameter at least of 5.0 cm and a thickness of at least 1 centimeter.
Another aspect of the invention relates to the expansion of the area of the single crystal from the seed crystal to the bulls nitride III-V group with the implementation of the growth in the transverse direction.
The following aspect of this invention relates to a plate obtained from the bulls nitride III-V groups of the above-mentioned type.
The following aspect of the invention relates to a polishing plate of the nitride III-V group to remove surface irregularities and provide the desired surface smoothness of the polished product - plate.
Another aspect of the invention relates to a method for the manufacture of boules nitride III-V group, including:
providing the same composition of the seed crystal of a nitride of an element of the III-V group for the bulls and
growing nitride material element of the III-V group on the seed crystal by vapor-phase epitaxy at a growth rate above 20, more preferably more than 50 micrometers per hour, to obtain the specified boules.
Although the present invention preferably use homoepitaxially C the grass, foreign substrates is also included in the scope of the present invention.
The following aspect of the crystalline material of the nitride of the element III-V group cut and/or polished with receiving surfaces lying in a-, C-, m - or r - planes, etc. or cut off slightly with respect to the primary plane of the crystal, with the receipt of vicinal plate. Both surfaces (ending in N or an element of group III) bipolar cut on the C-plane of the crystal can be polished for subsequent cultivation or manufacture of an electronic device.
Another aspect of the invention relates to a device structure that includes a plate, obtained from boules according to this invention, and to a microelectronic device or structure-the predecessor of the electronic device, made on the record and/or in it, for example to devices such as LEDs, laser diodes, ultraviolet photodetectors, heterostructure bipolar transistors, rectifiers high power components division multiplexing wavelengths, etc.
Other aspects, features and embodiments of the present invention will be clearer from the following description and the accompanying claims.
BRIEF DESCRIPTION of DRAWINGS
Figure 1 is an optical picture of the low increase of the seed crystal of GaN, obtained by epitaxy from the vapor phase hydride (APPG) and induced by laser separation.
Figure 2 is a schematic of the system APPG GaN to get the bulls in one of the embodiments of the present invention.
Figure 3 represents the x-ray double swing crystal plate GaN obtained by the method APFG the manufacture of boules in accordance with one embodiment of the present invention.
Figure 4 is a schematic illustration of an led double heterostructure made on the record obtained from the bulls according to this invention.
Figure 5 is a schematic illustration of laser diodes with cleaved facets, made on the record obtained from the bulls according to this invention.
6 is a schematic illustration of the UV photodetector fabricated on the plate obtained from the bulls according to this invention.
7 is a schematic illustration of a transistor with high electron mobility, made on the record obtained from the bulls according to this invention.
Fig is a schematic illustration of an amplifier high power, made on the record obtained from the bulls according to this invention
Fig.9 is a schematic illustration of a bipolar transistor with a heterojunction AIGaN/GaN, custom vinyl n-type GaN obtained from boules according to one embodiment of the present invention.
Describe the following patents and patent applications U.S. in their entirety are included here by reference:
The patent application U.S. No. 08/188469, filed January 27, 1994 in the name of Michael A. Tischler, and others, now published as U.S. patent 5679152;
The patent application U.S. No. 08/955168, filed October 21, 1997 in the name of Michael A. Tischler, and others;
The patent application U.S. No. 08/984473, filed December 3, 1997 in the name of Robert P. Vaudo, and others; and
The patent application U.S. No. 09/179049, filed October 26, 1998 in the name of Robert P. Vaudo, etc.
In this invention, a method for obtaining crystalline boules nitride of an element of groups III-V, such as (Al, Ga, ln)N, with a large cross-sectional area (> 1 cm in diameter) and a length greater than 1 mm, the seed crystals with the same crystal lattice. The deposition is carried out by vapor-phase epitaxy with high growth rate, eliminating the need for high-pressure apparatus, undesirable from a cost standpoint. Large area single crystal is provided through the use of the original crystal nucleating with a large area and the same crystalline lattice is Oh, for example, the actual crystals (AI,Ga,ln)N. the Cost of the individual plates is reduced in comparison with processes requiring removal of the substrate, as one bird can be divided into a number of plates for epitaxial growth and fabrication of electronic devices.
In this context, it is assumed that the term(AI,Ga,ln)N" is used broadly and includes, respectively, nitrides individual elements Al, Ga and In, as well as binary, ternary and Quaternary compositions of such compounds of elements of III group metals. Accordingly, the term (Al, Ga, ln)N combines compounds ALN, GaN and InN, as well as ternary compounds AIGaN, GaInN, and AlInN, and the tetrad connection AIGaInN as compounds included in this item. If there are two or more types of the component (Ga, Al, In), in a broad sense, the present invention can be used all possible compositions, including the stoichiometric ratio, as well as "non-stoichiometric" ratio (with respect to the relative molar fractions of each of the varieties of components (Ga, Al, In), which are present in the composition). Accordingly, it can be considered that the subsequent discussion of the materials GaN applicable to the receipt of various types of materials (Al, Ga, ln)N.
Below more fully discussed various aspects of the present invention, including growth on the seed crystal with eligible is th lattice and growing boules using a vapor-phase epitaxy (PFA) with a high growth rate.
The seed for growing boules
Nitride seed crystal from a uniform material, which is close in composition of the alloy material growing boules, reduce the stress associated with thermal expansion coefficient (TCR) and the effects of the mismatch of the lattices, and facilitate the growing material in the form of a long boules (> 10 mm in the axial direction) without cracking. A separate, freely spaced seed crystals (AI,Ga,ln)N can be obtained by any means, including (without limitation) grown on foreign substrates, thick film, which after growing separated by destroying the sacrificial substrate by thermal, chemical or physical means, or separate the film from the substrate (examples freely located materials (AI,Ga,ln)N and related methods of obtaining described in pending patent application U.S. No. 09/179049, filed October 26, 1998 in the name of Robert P. Vaudo et al., "(Ga,AI,ln)N with a low defect density and high-speed method a vapor-phase epitaxy to obtain it" ("Low defect density (Ga,AI,ln)N and HVPE process for making same") and in U.S. patent 5679152).
For example, the GaN seed a large area with a dislocation density of less than 107on cm2and an area of about 10 cm2easily formed using epitaxy from the vapor phase hydride and optical branches.
So exposal according to this invention enables to obtain high-quality material Buli (Al, Ga, ln)N, you can select individual records obtained in this way, for use as a seed for the subsequent reception of the bulls. Constant improvement of the characteristics of boules (for example, reducing the concentration of defects, reduction of background concentration, the increase in the area) can be done using seed obtained from successively improve material boules.
To ensure faster growth, improved crystallinity of boules or improved suitability for epitaxial growth and electronic devices, the seed crystal can be oriented in any number of ways, including (but not limited to) the C-axis, a-axis, m-axis or r-axis. In addition, the seed crystal may be cut at an angle of 10 degrees from the main axis of the crystal. It may be useful to direct the cut in a particular direction, for example cut 5 degrees from the (0001) plane can be directed in direction of the <1100> or <1120>. In addition, both sides of the seed (the surface with the end in N or an element of group III), oriented along the axis, can be used for growing boules, epitaxial growth, fabrication of electronic devices or improve the operation of the device.
Although it is less desirable for the method according to the invention can also be used and foreign straw and of such materials, as sapphire or silicon carbide. Stress and cracking, caused by the mismatch of thermal expansion or crystal lattices can be reduced in the seed, but not in bule, since the material boules has a relatively greater thickness.
Additionally, to mitigate differences in thermal properties and crystal lattices between the base of the seed and growing boules can be used malleable elements and other means. Alternatively, to eliminate complications caused by the mismatch of thermal expansion, you can use the separation or removal of foreign seed in situ.
In addition, to reduce stress, changes of the electrical characteristics, to reduce the density of defects, allow separation from the seed or the ease of nucleation during growth it is possible to use intermediate layers between the seed and the material boules. Such intermediate layers can be obtained in various ways, for example, vapor-phase epitaxy (PPE), chemical vapor deposition (CVD), physical vapor deposition (DGAP), molecular beam epitaxy (IPE), by epitaxy from the vapor phase ORGANOMETALLIC compounds (APVMA) or by epitaxy from the vapor phase hydride (APPG). Such intermediate layers can be formed from any suitable mater is Ala, including, without limitation, (Al, Ga, ln)N or other nitride III-V groups, SiC, SiN (which is one of the preferred materials of the intermediate layer to reduce the density of defects in bule), and oxides. Profiled intermediate layers can also be used to help reduce the density of defects and reduce stress, as, for example, in methods of lateral epitaxial growth. Intermediate layers can be formed by a chemical reaction, ion bombardment, etching the active ions or other modification of the seed crystal. Such intermediate layers may be uniform across the thickness of the seed, or you can profile for the desired effect on the nucleation during the growth, the Department of boules or improved material boules. The advantage profiled intermediate layers are more fully described in U.S. patent 5006914, Beetz, Jr., and in U.S. patent 5030583, Beetz, Jr.
In one aspect of this invention, the defect density of the product - Buli mostly reduced to a minimum by growing a thick boules and the use of suitable seed crystals, such as seed, which has a sufficiently low defect density at the initial time, or blades, which are shaped or treated otherwise to facilitate the annihilation of the defects during the growth of boules. The present invention is predpolagaetsya the use of seed, profiled corroded areas, or areas with the coating, preventing growth on specific areas of the seed side and accelerate growth in order to reduce the defect density. The present invention also provides the use of a pliable seed crystals, which are used to compensate for the mismatch of the lattices or thermal expansion coefficient of the material of the seed and the material of the bulls in achieving this goal. Applying the optimized seed crystals and the cultivation of the optimal thickness of the bulls, it is possible to achieve very low levels of defects in the resulting material boules. As monocrystalline seed crystal (Al, Ga, ln)N, obtained from bulls (Al, Ga, ln)N, can be successfully used for subsequent breeding of bulls, the characteristics of the material, including, for example, a decrease in the density of defects, impurity concentration and the increase in area can be continuously improved in the process of growing bulls, resulting in the best quality material for electronic devices during subsequent cultivation of the bulls and to the continuous improvement of the quality of the crystal nucleating derived from the specified material boules.
In one aspect of this invention, the seed crystals for the implementation of the method of manufacture of boules form by versiani the thick initial layer (Al, Ga, ln)N on a foreign substrate with the removal of this foreign substrate physical, thermal or chemical means. In one of these methods of forming a seed crystal of the same substance uses optical unit for removing foreign substrate.
The Department of film (Al, Ga, ln)N from a foreign substrate by means of optical separation is carried out by breaking the surface of the partition, called photon energy. For example, in the particular case of the seed crystal of GaN seed crystal of GaN can be grown on the plates of sapphire and then to separate or "detach" from sapphire laser heating of GaN thin region at the interface of GaN/sapphire for free GaN. For this purpose, through the sapphire transmit the radiation Q-include Nd:YAG laser with a wavelength of 355 nm. As the photon energy is slightly higher than the absorption band of GaN, the incident radiation is absorbed in a thin (70 nm) layer of GaN. A sufficient amount of absorbed radiation (for example, GaN - more than 0.3 j/cm2) causes thermal decomposition of a thin layer on the surface of partition and separation of GaN from sapphire. In order to obtain sufficient energy radiation, it is possible to use the beam is significantly smaller than the size of the seed; the beam can sequentially scan the surface for receiving the separated material GaN larger area.
Separation from in the native substrate by optical exfoliation can also be accomplished in situ during the growth process, moreover, the material (Al, Ga, ln)N support at a temperature close to the temperature of growth to reduce the stress associated with the difference of thermal expansion coefficient of the material (Al, Ga, ln)N and the foreign substrate. Alternatively, it is possible to separate at once, or one pulse, the entire record of the seed when using a sufficiently powerful source of radiation.
Structural characteristics of such seed crystals are very important for the final quality in growing bulls nitride III-V group. In order to verify the suitability of the seed crystal for a particular application, you can use transmission electron microscopy (TEM) in horizontal projection to determine typical density of defects on the top surface of the seed. For GaN, for example, a density of defects on the top surface of the seed crystal preferably is less than 107cm-2that is well comparable with the density of defects observed in epitaxial GaN large area.
The growth of boules
The precipitation of the (AI,Ga,ln)N in accordance with this invention for growing boules is carried out mainly using the method of vapor-phase epitaxy (PFA) with a high growth rate. As growth in the vapor phase is further from equilibrium than in the ordinary methods of volumetric growth, and monopodial a greater number of N-containing reagent in comparison with elements of group III, it is unnecessary in high-pressure apparatus.
The growth of boules according to this invention is carried out mainly under certain process conditions to obtain the bulls nitride of an element of the III-V groups for substrates of higher quality.
To obtain the desired high throughput with acceptable overall duration of the process is used mainly in the rate of growth of more than 50 μm/h, with preferred are the growth rate of more than 200 μm/h, and most preferred is the growth rate of more than 500 μm/h Growth mainly carried out at temperatures between about 900 and 1100°for GaN, between 950 and 1200°for AIN and between 700 and 900°for the InN; for the cultivation of the alloy is necessary to specify the temperature between these values, which can easily assistants by direct experimental determination.
Predecessors to the way PPE can include, but are not limited to, hydride, chloride or ORGANOMETALLIC precursors. To obtain compounds of element of group V you can use the NH3or other N-containing precursors, such as hydrazine, amines, polyamine etc. the composition of the alloy in bule easily adjusted individual threads compounds precursor of group III elements. The flow of N-containing precursor of predpochtitel what about the support at a much higher flow rate, than the flow rate of the connection predecessor element of the III group (for example, it is common to the flow ratio NH3/compound of element of group III from 10 to 1000, depending on the share of decaying NH3).
When introduced into the reactor, where the cultivation of appropriate precursors must have sufficient residence time in the reactor to provide the necessary mixing. The time required for mixing N-containing precursors and precursors containing an element of group III, should usually be less than about 20 microseconds, in order to minimize side gas-phase reactions.
Alternatively, you can mix predecessor(s)containing the element of group III, with a nitrogen-containing precursor under normal conditions with the formation of a stable liquid composition, which is then fed into the reactor to grow with the use of system fluid supply, for example, of the type described in U.S. patent 5204314 and 5536323 (Kirlin et al.). In this process a liquid solution evaporates from the vapors of the precursor, which is transferred into the reactor to grow for the implementation of the epitaxial growth. Typical precursors V groups include amines, polyamine, hydrazine, etc. and the typical predecessors III groups include halides, hydrides, metal is organic compounds, etc. Some precursors containing elements of group III, can be mixed in the same solution to obtain the bulls binary or ternary nitrides, and precursor of the alloying element can also be mixed in the solution to obtain doped boules n - or p-type.
The density of defects in the product-bule preferably minimize by growing a thick boules and the use of suitable seed crystals, such as nucleating with initially provided corresponding low defect density or seed with a specific profile or processed in other ways to facilitate the annihilation of defects during growth of boules. In the alternative case, for this purpose also useful malleable (capable of deformation) crystals-seed, which compensates for the mismatch of the lattices or temperature coefficients of expansion of the material of the seed and the material of the bulls. Using the optimized crystal-nucleating and growing optimally thick boules can be achieved very low levels of defects in material obtained boules, for example in the practical implementation of the present invention can achieve a density of defects less than 104cm-2.
For the subsequent growth of GaN boules can be used with success monocrystalline seed crystal of GaN obtained from the GaN boules. Tightly the th defects gradually decreases during the growth of boules, which results in the re-growth to receive the best quality material for electronic devices.
Plate with a large area are of more commercial interest than the plates of a smaller size, because larger plates you can get more electronic devices. It is preferable to obtain the plates of large area, however, the original seed, for example, of GaN, may be of limited size. For growing GaN on the seed should regulate the growth conditions of the GaN boules, for example, by using a higher temperature growth, higher ratios of NH3/Ga, a lower pressure, the desired temperature gradients and non-uniform flow profiles, so that the GaN single crystal grown in the direction perpendicular to the seed, and in the direction parallel to the seed. The edges of the seed must be a naked face of the single crystal, in order to facilitate replication in the lateral direction. In this way, along with the growth of boules area of the single crystal GaN boules there will be more. The plate of single crystal GaN large area can again be used as a seed to get the bulls even bigger. At each subsequent growing area of the GaN single crystal can therefore be expanded. In addition, the impact on Okoye surface growth or crystal plane can increase the rate of lateral growth and to accelerate the expansion of boules in the lateral direction.
To avoid reduction of the area of the single crystal, you should try to minimize side polycrystalline growth of dendrites on the edges of the seed. Ensuring naked faces of the crystal, which enables the growth of high-quality material in the lateral direction, to prevent the reduction of the area of the single crystal. Alternatively, the edges of the crystal can be covered with material - inhibitor of growth (for example, SiO2or Si3N4in the case of GaN), to minimize any increase over the edges.
In addition, to control crystal formation can be used additives (surfactants) in the beginning or in the course of growth. Surfactants can be used to regulate patterns (for example, cubic or hexagonal), uniformity of growth and/or inclusion of alloying elements. In the compounds semiconductors can change the order packing of atoms (the atoms are positioned one relative to another at a constant atomic ratio), which, in turn, affects the physical, electrical and optical properties of the crystal. For example, in SiC were identified over 200 different packaging methods, or polytypes; the most common are 4N, 6N, 15R and 3C. In GaN to date were obtained cubic, Gex is analny (2N) and rhombohedral (9R) polytypes (see, for example, N. Seike et al., J. Cryst. Growth, 208, 57 (2000)).
Get POSITIP can be controlled, in particular, by regulating the temperature of growth (Matsunami, W.S.Yoo, PhD Thesis, April 1991, Kyoto University), the pressure, the crystal orientation of the seed crystal or substrate (for example, the use of vicinal surfaces as a matrix) and the presence or absence of selected impurities (N. Iwasaki et al., Appl. Phys. Lett., 63, 2636 (1993)). These impurities may be affected with the change in the structure or chemical properties of the surface, by education relations mainly at certain points on a flat or stepped surfaces, respectively, without changing the packaging. Alternatively or in addition, impurities can alter the bulk properties of the crystal (making small changes in lattice constant or the electronic structure), which, in turn, affects subsequent packaging layers. The presence of certain impurities or fractions of all components present growth can also affect the introduction of alloying elements (epitaxy when competition for active sites) (D.J.Larkin, P.G.Neudeck, J.A.Powell and L.G.Matus, Appl. Phys. Lett. 65, 1659 (1994)) or the quality of the crystal (S.Nakamura, T.Mukai, M.Senoh, Jpn. J. Appl. Phys. 31, 2885 (1992)).
The crystals of the seed carefully prepared, to enable playback of the crystal structure and to minimize the appearance of new defects during R is a hundred bulls. The seed crystals are preferably polished and etched to remove surface defects and carefully cleaned to remove any contaminants before growing boules.
In General, the process conditions can be easily determined empirically by changing the specific process conditions using response characteristics of the material boules. Some of the important characteristics of a material that can be optimized are the defect density, surface morphology, crystallinity, electrical and optical properties, as well as damage caused during the processing of material and manufacturing records. The defect density can be characterized by measuring the correlation PAM with decorative etching (hot sulphur/hot phosphoric acid) and/or microscopy atomic interaction (MAV). Surface conditions can be estimated using the MAV, scanning electron microscopy (SEM), optical microscopy Nomarski (Nomarski), Auger electron spectroscopy, diffraction of slow electrons, Kelvin probe, electron diffraction spectroscopy (EDS, EDS), and other suitable analytical methods and devices. The degree of crystallinity can be assessed using dual x-ray diffraction on the crystal, quadrupole diffraction x-ray beam of the nd crystal and optical studies through cross-polarizers. The electrical properties can be characterized using the Hall effect and the measurements of capacitance and voltage. Optical properties (photoluminescence measurements at room temperature and low temperature. The orientation of the bulls can be characterized by Laue diffraction. The polarity of the seed or boules can be easily identified by the methods of etching, the methods of Auger electron spectroscopy, lowenergy electron diffraction and EDS. The defects of the surface layer can be determined by etching and/or a method of increasing epitaxy from the vapor phase ORGANOMETALLIC compounds.
In the process of growing the capacity to grow should ensure to minimize the time of mixing of the precursors containing an element of group III, with precursors containing the element of group V, at the same time providing a homogeneous mixture of individual precursors and alloying additives. To facilitate the mixing of gases, it is possible to use a concentric design of the inlet to flow in the cell cultivation and/or use of a rotating crystal, the seed crystal. It is desirable that the vessel for growing was designed and made so as to be able to recharge the source material, so that the length of the bulls was not limited by the supply of reagents. Similarly, it is desirable to carry out posted by the e and the processing of by-products of the process with a high performance filter so the process is not stopped or changed in an undesirable direction when the pressure in the vessel for growing.
Method of epitaxy from the vapor phase hydride (APPG) is a highly effective method of growing bulls nitrides of elements of the III-V groups on the seed crystal of the same composition, as it provides a high rate of growth in use it is able to fill predecessors, with low cost, and it has already proved its suitability as a method of manufacturing arsenide and was semiconductors.
In the process APPG, using as example GaN, HCl is passed over a source of gallium (Ga) high purity; forms volatile GaCI, which is transferred to the area of deposition, where it reacts with ammonia (NH3) with the formation of GaN. The process in General, including education GaCI, the decomposition of NH3and the formation of GaN, can be successfully carried out in the reactor with heated walls.
For economical deposition in obtaining long boules desirable high growth rate. When APPG it is desirable to cause the maximum surface area of the metal gallium, as the supply of gallium chloride (or other sources of the element of group III to PFE) and his education limit the rate of growth in the process. You can use a growth rate higher than 0.15 mm/h, which is considerably higher than karasti, achieved by epitaxy from the vapor phase ORGANOMETALLIC compounds (APPMA), molecular beam epitaxy (IPE) or growing GaN from solution at high pressure. This high rate of growth is facilitated by the effective decomposition of NH3in the hot zone of the reactor and the preferential reaction between NH3and chloride Galiya at a temperature of growth.
To achieve the desired quality and morphology of boules can also regulate some aspects of the growth process. The distance between the input holes for gas and increasing the surface strongly affects the quality of the crystal, and it can be adjusted as necessary to obtain the desired result. It is desirable to maintain the distance between the input apertures and the surface of the growth constant during the growth process to ensure homogeneous mixing of the gas, at the same time minimizing the preceding reaction and keeping the temperature constant.
Thus, for example, Buhl may be secured in the clamp, and in the process of growth bull can be discharged back through the respective carriage, a moving platform, clamping gear device or other suitable structure, to maintain the above-mentioned distance between the surface of the growth and the source of steam predecessor permanent sludge is another suitable value in the growth of boules, in order to carry out the process of growth "isothermal", i.e. to make the growth process as isothermal as possible, and thus reach high quality and isotropic characteristics of the bulls and made from her plate.
Alternatively, during the process of growth, you can change the temperature profile to compensate for the increasing amount of Buli and the resulting differences in temperature along the axis.
In addition, you can change the overall temperature level, in order to maximize the quality of the product. For example, films (AI,Ga,ln)N usually have a lower background carrier concentration when grown at higher temperatures. However, cracking, resulting from residual stresses between heterogeneous seed and the growing crystal, is minimized when using lower temperatures of the seed. Higher temperatures, however, promote lateral growth and can be used for the extension of the area of crystal boules. Thus, growth can be initiated at a lower temperature, then the temperature can be increased to grow the material of higher purity and increase the chip area, if a higher temperature is not a problem of cracking. In General, the temperature can modificarea the ü in the process of growth of boules to influence the properties of the growing film.
The purity of the reactor and the reproducibility of the growth in the growth process are vital in the process of growing bulls, and it should be maintained through periodic in-situ etching (cleaning etching) components of the reactor. This purification step can be performed by passing into the reactor HCl or other purifying reagent at a temperature of growth or near it. Alternatively, or in addition to periodic etching a small amount of HCl or other purifying reagent can be used in the course of the growth cycle for minimizing the buildup of solids and precipitation on the details of the reactor. Cleansing agents can be directed to the walls of the reactor in order to facilitate or improve the removal of sediments. Such cleaning procedures are also significantly increase the potential use time machine system for growing. As another approach you can use in the reactor replaceable liners and change them to improve the purity of the reactor and/or time.
The conductivity of the material (AI,Ga,ln)N can be adjusted by introducing impurities of n-type, p-type and/or deep levels in the gas phase in the growth process. Adding impurities of n-type, such as silicon or germanium, for example, using silane or tet is hydrida Germany in the gas stream in the growth process can be used to control the conductivity of n-type material. Accordingly, the addition and activation of the impurities are p-type, such as beryllium, magnesium or zinc, using ORGANOMETALLIC or other sources of these elements are introduced into the gas flow during the process, can be used to control the conductivity of p-type material boules and records obtained from this boules. When implementing this method, it is preferable that the concentration of donors and acceptors ranged from 1×1015up to 1×1020cm-3; more preferred are concentrations in the range of from 5×1017up to 1×1019cm-3.
The production of the material Buli (AI,Ga,ln)N and plates p-type has a positive effect on the production of bipolar devices (for example, light emitting devices such as LEDs and laser diodes). Characteristics of such devices and flowing currents are limited largely to the high resistance electrical contact with the p-layer device. The use of substrates of the p-type gives the possibility of formation of significantly larger (10x) p-electrodes and the respective reduction of the resistance of the p-contact. Operating temperature and the functionality of laser diodes (AI,Ga,ln)N on the plates p-(Al,Ga,ln)N with a larger area of the p-contact is used to significantly improve the obtained output power and Uwe is icene time of operation of such devices.
Politology character boules can be ensured by establishing a balance between the residual shallow acceptor (or donor) and deliberately put on a deep level donors (or acceptors). For example, where there are similar concentrations of impurities of the n - and p-type, it may be necessary to introduce a small amount of surface acceptors (donors)to lock type conductivity, which is compensated by donors (acceptors) deep level. Getting politology substrates requires a low concentration of impurities. The background concentration of impurities in the material boules can be minimized by the use of the materials of the reactor or liners, not containing Si and O (for example, components covered AIN), and use raw materials of high purity (NH3is a known source of impurity oxygen). Since a sharp reduction of background impurities is observed with increasing distance from the surface of the seed growing long boules helps reduce background impurities.
Impurities deep levels are a useful inclusion in the material of the nitride boules item III-V group during the growth substrate to compensate for residual electrically active impurities. The concentration of acceptors and/or donors deep levels, it is desirable to accurately monitor the performance, to fully compensate for the material surface impurities, residual or intentionally introduced and present in low concentration. This compensation gives a material with high resistance, in which the Fermi level is located near the center of the forbidden zone. Levels should also be deep in the forbidden zone, to avoid subsequent thermal ionization sources, especially for high-temperature/high-power devices. Many transition metals, including Fe, Cr and V, can be useful particles as alloying additives of deep levels in GaN and other materials nitrides of elements of the III-V groups, creating a deep electronic States in the forbidden zone. Other alloying additives deep level that can be used are As, Mn, Co, Ni and Cu.
In addition, the conductivity of the bulls can be changed after growth is completed.
One way to change the conductivity of the bulls is alloying with nuclear transformation, with which you can achieve a more homogeneous distribution of alloying and/or increased concentration of electrically active doping agent. Although this is discussed below with respect to GaN, it can be understood that this method can be suitably applied to other materials that contains the element III-V group, is within the scope of this invention.
Alloying with nuclear transformation of material GaN carry irradiated by thermal neutrons. The captured neutrons created in the crystal radioactive isotopes atoms of Ga and N, which in the decay turn into a dopant in the GaN crystal. In the production of silicon doped with nuclear transformation was used to carry out the doping of silicon with phosphorus extremely homogeneous distribution of the alloying additives, but this method has not previously been applied to semiconductor materials of nitride compounds, such as GaN and related alloys. As applied to the materials of the nitrides of elements of the III-V group has several anticipated benefits of alloying with nuclear transformation, including:
(1) the ability to obtain the concentration of electroactive of alloying elements in excess of those achieved by the introduction of alloying elements during growth, as the concentration of the alloying additives are not limited solid solubility of the impurity in the material;
(2) the use of alloying with nuclear transformation is significantly more effective, for example about 10 times more efficient than conventional silicon doping, and the problems associated with other interfering reactions, typical of the alloys of semiconductors under normal alloying, are minimal for legirovanie the nuclear transformation;
(3) when doped with germanium (Ge) via nuclear transformation Ge alloying additive will be only in the place of Ga, and it is unlikely that Ge alloying additive formed a bond with other particles present in the gas stream, which increases the efficiency of doping (with a single activation energy) and eliminates the need for activation, for example, in such a way as annealing;
(4) alloying additive is distributed very uniformly, and all Buhl in General can be doped at the same time;
(5) the doping of the grown GaN by means of nuclear transformation net on the isotopic composition of the71 31Ga with the aim of increasing the efficiency of neutron capture reduces the cost of the alloying process by irradiation with the potential increase in thermal conductivity; and
(6) the doping method of nuclear transformations can be used to legitamate as a bird, and a separate plate (obtained by any method) and epitaxial films.
As an example of the effectiveness of doping nuclear transformation (transmutation) consider the effect of thermal neutrons on Ga. Occur the following reaction:
N.A.=60,1%, 1.68 barn, τ=21 min
N.A.=39,9%, 4.7 barn, τ=14,1 h
Of these reactions shows that the irradiation of GaN Teplov the mi neutrons can give one of two Ge isotopes with high efficiency. The half-life obtained unstable isotope is an acceptable short. Ge will remain at the space that was occupied by Ga. Because the alloying additive is not obtained in the course of growth, decreases the likelihood that the alloying additive will be compensated, for example, N, which eliminates the need for additional stages of recovery.
On the other hand, the effect of thermal neutrons on N may not be significant.14N is 99,63% from natural N. a Small cross-section of neutron capture, a high natural content of14N and stability15N minimize the likelihood of any significant changes in electrical properties under neutron transmutation.
Getting Ge impurities of n-type on the place occupied Ga, this method allows to achieve a high degree of homogeneity of the doping and avoid the harmful effects of high concentrations of impurities in the reactor during growth. Fragility, which in other cases may occur when high concentrations of alloying with other methods of doping, will also be lowered by alloying nuclear transformation.
Neutron-irradiated GaN will give the following isotopes:16 7N70 31Ga and72 31Ga. These isotopes, in turn, decay into isotopes with half-lives 2,31 min, 21 min and 14.1 hours cross-Section of neutron capture by nitrogen almost an order of magnitude less than this value for Ga, but nevertheless, in addition to Ge can get the alloying additive is oxygen.
Radioactivity obtained by irradiation at a level sufficient for the formation of 1×1019of Ge atoms in a cubic centimetre first GaN high (> 105Curie), but due to the short half-lives activity will decrease until several microcure 10 days.
Method of alloying nuclear transformation can be applied to other materials that are prone to cracking, or those in which it is difficult to obtain high levels of doping in other ways, such as silicon carbide.
In other cases, to achieve the desired levels of electrical conductivity can also be used diffusion of impurities of n-type, p-type or deep levels at elevated temperatures.
Boules grown in accordance with this invention, can have any dimensions suitable for the end-product applications - records obtained from the bulls. For example, the bull may have a square cross-section (side) 5-10 square centimeters or more, and may have a length of 4-5 mm, or even longer. Buhl must have sufficient length to split it on a plate or other way to share this material on a separate plate (for example, a thickness from 0.1 to 0.7 mm).
P the following growing boules, to divide it into layers with the aim of obtaining the plates, the bull can be oriented using conventional processes x-ray diffraction Laue or θ-2θ. In the case of Laue diffraction polychromatic x-ray beam falls on the crystal along the direction , and the corresponding condition for Bragg additive interference wavelengths there is a certain beam Laue, forming a spot associated with the crystal plane of the material, whereby it is possible to accurately determine the orientation of the crystal. If θ-2θ x-ray diffraction incident on a crystalline solid x-rays are scattered and additive interfere with each other, forming a receiving optics. The diffraction angle is called θ angle, and, as usually diffractometers measure the angle that is twice θ corner, such that the measured angle is usually called the angle of 2θ. On the basis of the wavelength of the incident x-ray radiation and angle 2θyou can solve the Bragg equation to determine the precise orientation of the crystalline solid. The above-mentioned methods can be used for orientation boules with the aim of obtaining further records a specific crystallographic orientation. The bull can be cut (divided into plates), using any tool, suitable for cutting, such as a saw (on nutrena or outside diameter), or most preferably a wire saw. Plates can be oriented along the principal crystallographic direction, or orientation may be slightly (less than 10 degrees) offset to provide a stepped surface for subsequent epitaxial growing or breeding bulls. Specific crystallographic orientation may be preferred for the subsequent epitaxial growth due to their advantages in terms of quality epitaxial crystal morphology of the epitaxial surface, the inadvertent exclusion of alloying elements, the inclusion of alloying elements and activating properties of the alloying additives, electrical and/or optical properties, the ability to splitting, increased carrier mobility or benefits of production or other characteristics of the device. Buhl may be subjected to Litovka and alignment before cutting, or Litovka and alignment carried out on separate plates. Litovka and alignment can be performed using conventional grinding (Buli) or bombardment or polishing particles, a separate cutting with a wire saw, drilling or cutting laser (plates).
Plates can be polished on the edges. After forming the billet plates plates polished to a desired image quality is of the surface for epitaxial growth of GaN or other material. The polishing plate is abrasives gradually decreasing sizes. For example, the first plate collet seats itself in coarse abrasive (for example, with a diameter of abrasive particles of 10-30 microns), then the average abrasive (for example, with a diameter of abrasive particles 3-10 microns). Then the plate is polished with a thin abrasive (for example, with a diameter of abrasive particles of 0.1-3 microns). You can use one or more stages of lapping and/or polishing. Can be used such abrasives like aluminum oxide, silicon carbide (SiC), boron carbide, diamond and other materials harder than GaN (or other nitrides of elements of the III-V groups in question). The plate can be subjected to mechanochemical polishing (MHP) to remove any damage to the surface caused by mechanical polishing. The MHP process can be done in the main suspension (pH>8) or in acidic solution (pH<6). To increase the speed of MHP in suspension can be added oxidant. For MHP GaN, you can use colloidal silica or aluminium. Alternatively, after mechanical polishing can be applied to the etching of the active ions, electro-etching or photoelectrochemical etching for processing records and eliminate damage to the surface.
Vinyl GaN can be polished on one side or on both sides (doctorand what I polishing), as the need for specific follow-up application of the plate. The plate can be subjected to chemical etching or before the stage of lapping or before the stage of polishing. The composition of the etching solution may be of any suitable type, such as hot acid or hot alkali.
In General, vegeatrian plate GaN can be damaged in the surface layer caused by mechanical action of the polishing particles. Surface damage can create defects in the subsequent epitaxial growth of films of nitrides of group III elements. There are several ways the characteristics of these surface damage. Examples include epitaxial growth in order to detect subsurface damage, treatment to detect subsurface damage, x-ray topography to produce images of the subsurface damage, transmission electron microscopy (TEM) and ultraviolet (UV) photon backscattering spectroscopy to produce a map of the distribution of damage. X-ray topography and UV-photon backscattering spectroscopy is non-destructive and can be applied to detect defects. In the case of UV-photon spectroscopy of the inverse scattering defects in plates GaN have different characteristics on the Russ is of light and therefore can be used to determine. Epitaxial growth is the most direct way to determine damage during polishing, but for the record he is destructive. To detect damage during polishing can also use some methods of etching, which are also destructive when used for decoration of defects, such as chemical etching, electrochemical, photoelectrochemical etching, the etching of the active ions (TAI), high-temperature annealing or annealing in a reactive atmosphere.
The methods specified above characteristics can be used to determine the nature and extent of subsurface damage of the plate in addition to the ways to remove or minimize surface damage, for example, by chemical etching, mechanical polishing (MHP), thermal etching or etching the active ions (TAI) (based on chemistry Cl or CI-F).
In the preferred implementation, it is desirable to provide an accurate (smooth) surface treatment of the plate with the average quadratic deviation of roughness of less than 5 angstroms in the area of 10×10 square microns, measured on microscope atomic interaction. It is desirable that the plate had a radius of curvature more than 1 meter. For more planes you can use polishing, but it can be applied in the t to be hard to focus with high accuracy. The plate may have a plane that is oriented with an accuracy of better than ±0.3 degrees. This exact plane in the alternative can be obtained by splitting.
It is desirable that the plate was of sufficiently high quality to serve as a basis of led devices in the application for LEDs. In the application of laser diodes, it is desirable that the plate was of sufficiently high quality to serve as the basis for the laser diode device that generates at room temperature. In applying for transistors with high electron mobility (GE) intake plate must be of sufficient quality to serve as a basis for such are the devices.
With regard to the use of the plate as the substrate for the manufacture of structures of microelectronic devices, the usefulness of the plate is determined in part by physical form. In particular, if the plate is bent, if the thickness of the plate is changed, or if the plate is warped, the possibility of obtaining small parts of the image using optical lithography may be difficult or even disappear. In addition, the possibility of growing high-quality epitaxial films on the disc can be compromised as part of the plate in contact with podarkticules changes and thus the nutrient, heating is non-uniform. To the substrate of the nitrides of elements of the III-V groups, such as the GaN substrate were suitable and viable commercially desirable, the following restrictions on the structure of plates:
the deflection of the plate must be less than 1 m (radius of curvature), and more preferably less than 4 m;
the total deviation in thickness (CBOs) should be less than 20% of the average thickness of the plate, and more preferably less than 5%; and
distortion (measured as the difference between the high and low points on a given surface) should be less than 50 microns, and more preferably less than 10 microns.
Applying the foregoing criteria to receive products - records of bulls according to this invention ensures that the plate will be suitable for subsequent fabrication of microelectronic devices on or in this record.
The specific implementation of the method of obtaining the bulls (Al, Ga, ln)N
The method according to this invention can be obtained by using epitaxial growth from the vapor phase with a high speed crystal boules (Al, Ga, ln)N having a large cross-sectional area (e.g., > 1 cm in diameter) with a length of more than 1 mm on blades with the same crystal lattice. The growth rate can be, for example, more than 20 microns per hour at a temperature of from about 900 to 1200#x000B0; With, and for GaN preferred temperature lies in the range of from about 900 to 1100°and for AIN preferred temperature lies in the range of from about 950 to 1200°C.
In one specific illustrative embodiment of the GaN boules were grown on the seed crystal of GaN. One of these blades is shown in figure 1. This seed was obtained by growing the 300 µm GaN by epitaxy from the vapor phase hydride (APPG) on sapphire followed by the separation of GaN on sapphire by using the heat produced by laser GaN thin region at the interface of GaN/sapphire. Crystal is a seed crystal of GaN was transparent and provided the seed in the absence of stress for further growing the GaN boules.
Subsequent breeding bulls can easily be done by epitaxy from the vapor phase hydride (APPG) in the system with a reactor of this type, as shown schematically in figure 2.
As can be seen from figure 2, there is shown schematically the system of the reactor 10 includes a reaction vessel 12 with highlighted inner volume 14. Because the system figure 2 shows the illustrative purposes from the point of view of integration and orientation, it should be noted that in some embodiments, execution of the present invention, it is preferable to compose the reactor in the form of a vertical reactor system. For gas supply to the reaction vessel 12 are attached line MoDaCo silane, line 18 feed ammonia and line 20 of the feed hydrogen chloride (HCl). Each of these lines 16, 18 and 20 of the reagent supply connected to respective capacitances of the source gases or other sources for filing strip (not shown). Line 20 filing HCl is connected with the internal compartment 22 of the reaction vessel 12 that separates a limited amount 24 of the inner volume of the reactor. This limited volume 24 has a reservoir 26 containing molten gallium 28.
The internal volume 14 of the reaction vessel 12 also includes a retractable polictial 36, secured to the rod 38, which, in turn, is connected to a drive motor (not shown), for example an electric motor, a gear structure type actuator cremallera, piston Assembly, providing the movement, carriage or other moving structure to selectively move the rod 38 in either direction, these double-arrow A. In a preferred embodiment of the present invention also improves the temperature uniformity of the growth and distribution of the particles of the reactants due to the rotation of the rod 38 in the course of growth.
The system shown in figure 2, can be modified in comparison with the specified option run. For example, this system may include the replacement of metal by using a provided on the of Osom vessel, which is heated to supply metal in liquid form in the growing chamber. The location of the system, as discussed above, may be vertical, and the system in another embodiment may include a means to enter HCl for cleaning camera for cultivation, the lining in the chamber for growing and/or a device for filtering/sparging for filing other reagents.
At the end of the rod is fixed polictial 36, which may be suitably heated, for example by surrounding the furnace and/or by using the embedded electric heating element resistance, the incident infrared radiation impinging microwave radiation or other means (heater not shown). It should be understood that usually heats up not only polictial, for example, from the hot wall reactor in which all the growth zone and the zone of gallium metal enclosed in the furnace of resistance. On polictial pinned crystal, the seed crystal 34, which grows Buhl 32. Buhl is growing from vapor precursors that are mixed from the supply lines 16 (silane), 18 (ammonia) and internal branches 22 (gallium chloride obtained by the reaction in this branch of gallium with HCl)vapor space 30 of the inner volume 14 of the reaction vessel 12.
In the vapor space are connected to respective predecessors, and arid gallium (GaN) is formed on the surface of the crystal growth of the seed in the initial work, with the subsequent distribution of growth by deposition in the axial direction of the elongated reaction vessel.
Along with the growth of boules rod 32 and the associated retractable polictial you can move with purpose step pull-out rod and Assembly of podarkticules from the reaction vessel 12. The consequence of this move is to remove the surface growth from the outlet openings of the lines 16 and 18 of the inlet and the outlet of the inner compartment 22, and such movement can be controlled during the growth process to maintain the distance between the surface of the growth bulls and output holes predecessors at a constant level, so that the surface growth bulls were supported thereby in isothermal condition as it grows, and the mixing time of the original materials were maintained constant as the growth of boules. In addition or alternatively, you can regulate the temperature of the reaction vessel to achieve the desired properties of the bulls obtained in this reaction vessel.
In APPG growing boules use the inherent mechanism of annihilation of defects, which is most used in the growth APPG in appropriate conditions, including a gradual decrease in the density of defects in material thickness APFG (which is more fully described in the patent application With The And No. 09/179049, filed October 26, 1998 in the name of Robert P. Vaudo et al.). For example, using as illustrations GaN, dislocations in APFG the GaN material continue to be inclined relative to the direction of growth and to each other as the film growth. Reproducibly achieved levels of dislocation less than 5×106cm-2on the GaN layers with a thickness of 200 to 300 μm on the sapphire, and such levels of defects are easily achievable with the implementation of this invention, as well as a lower density of defects, for example less than 104cm-2. Since these dislocations are still inclined after hundreds of microns growth, annihilation of dislocations in inclined dislocations will continue to grow boules. Of course, the ability to maintain the annihilation of dislocations will depend on the nature of the remaining dislocations. This ability can be improved by (i) growing longer boules and (ii) the use of seed, which received further during the process of growing bulls (i.e. the use of blades, cut off from the bulls after he had been a decrease in the density of defects).
Because the reagents for the process APPG can either download in large quantities (like Ga), or periodically replenished during growth or to serve permanently as HCl, NH3), the process can be improved to grow very long boules. Virus is of boules on the "same type" blades (from the same nitride of an element of the III-V group) is crucial for obtaining long-term bulls, eliminating cracking due to stresses caused by mismatches. As for the value of cultivation on seed agreed coefficient of thermal expansion (CTE), if growing boules spend on a seed, which has a different CTE than the grown nitride of an element of the III-V groups, when cooled from the temperature of growth of the nitride of the element III-V groups and the substrate will be under considerable tension, and material boules and/or the seed will be inclined to crack; but if the growth is performed on the seed of a nitride of an element of the III-V groups, coordinated by CDC and the structure of the crystal lattice, can be growth without stress, and cooling the bulls will be without cracking. When a sufficient supply of reagents and grown on the seed crystal, coordinated by the CTD can be grown boules several centimeters in length.
It is possible to obtain a substrate with a significantly lower density of defects, if we start from the seed of the nitride of the element III-V groups with lower defect density obtained by lateral epitaxial capacity (BEN).
BEN carried out on substrates that were profiled areas of growth inhibitor formed by deposition (e.g., Si3N4W or SiO2) or etching (grooves). The selectivity of growth between maskiri the data (or protravlennye) areas and intermediate areas ("Windows") changes the direction of growth and the distribution of defects in the nitride of the element III-V groups. Annihilation of dislocations occurs by "blocking" in the areas of inhibited growth, and by turning the dislocations in the intermediate region "Windows". Thus, you may experience a lower density of defects not only in the areas of inhibited growth, but also in the intermediate areas "Windows". Repeating the process with BEN stripes inhibited growth placed to block the entire area of the seed can also be useful for obtaining the seed uniformly low density of defects.
Boules (Ga, Al, ln)N can be grown on previously cultivated by the way BEN blades, or the process of growing bulls may include growth BAINS as a first stage, without removing material BAINS from the reactor.
In APFG the process of obtaining the bulls, in addition to the nucleating GaN with high quality, it is important that the growth process was thermally homogeneous, in order to avoid local stress. This can be achieved, for example, the use of relatively low temperature growth (e.g., from about 900 to 1100° (C) when using the heat from the hot walls of the reactor to maintain a uniform temperature in the growing bule.
Efficient transformation of boules nitrides of elements of the III-V groups in plate includes orientation bulls cutting bulls, Litovka plate, polishing plates and and characterization plate. With regard to the orientation of the bulls, the exact orientation of the plate is important for proper deposition of epitaxial layers of a nitride of an element of the III-V groups. To determine the direction of the crystal can be applied Laue diffraction, and the polarity of the original seed and boules can be easily determined analytically using the appropriate methods, for example methods of surface analysis, including ECO, the diffraction of slow electrons, etching and x-ray photoelectron spectroscopy.
After orientation Buhl cut into blanks for records. For this operation you can use a wire saw. The principle of the wire saw is cutting boules on the plate using the process of mastication. In this process steel wire with brass plated causing the abrasive slurry (diamond/SU); wire coated move on bule, and with each pass removes a small amount of material boules. Alternatively, you can use wire, impregnated with abrasive. This process can be done even if only a few, such as 125, wires placed in parallel positions, which allows to separate the appropriate number of plates from one or more bulls in one operation cut.
The use of wire saws instead of other devices for cutting to place the ins has three major advantages: (1) a lower loss in the kerf in the implementation process of the separation plate; (2) higher performance due to the separation of many wires, and (3) reduced the amount of surface damage during the separation plate. Due to reduced losses in the cut the number of plates that can be obtained from one boules, is very high.
Alternatively, the bull can be divided into separate plates by thermal decomposition applied periodically separating the layers. For example, the composition or doping level Buli (Al, Ga, ln)N can be adjusted along the length of the bulls so that periodically (for example, after each 0.3 to 0.5 mm growth) can grow adsorption layers (areas with smaller bandgaps, or with different types or density distribution of alloying elements), alternately with layers or areas of the material of the plates. Irradiation received boules energy high-power laser with a photon energy that is not absorbed (or minimally absorbed) layer of the material of the plate, but preferably or exclusively absorbed by the absorption layer, causes thermal decomposition of the absorption layer and the separation material layer plates from the bulls. This process can consistently perform to separate each layer of the plate from the bulls, perhaps with the removal of surplus materials containing an element of group III, with the surface of the bulls (EmOC is emer, in gaseous or liquid HCl) before each successive stage laser separation or during it.
The process of obtaining records or separation gives individual separate body plates; unwanted external area of the plate is removed during Litovka. This is cut to the exact size and rounded edges can be achieved through controlled by the computer of the grinding process of the microparticles. In this process two streams of abrasive particles, such as boron carbide, can be used for slicing viersprong plates of SiC on a round plate with the corresponding planes. Preferably, the system is computer controlled to obtain the exact diameter of the plate and the lengths of the planes, as well as to obtain plates with rounded edges for increased resistance to cracking and splitting. Before the separation of the plates are also Litovka; in this case, you can get a higher output.
Polishing plate includes a preliminary polishing, for example, using diamond suspensions, with subsequent treatment after polishing to remove the surface damage arising from the sawing and mechanical polishing.
Obtained from boules plate can be subjected to various other processing operations, including,without limitation, drilling, processing the stream of abrasive particles, cutting with a wire saw, laser processing, mechanical polishing, etching, and the etching of the active ions.
In one aspect of this invention provides for the possibility of cleavage of the substrate for a microelectronic device or structure for the device precursor, to obtain devices such as laser diodes on free-located material. Homostructure give the opportunity to get aligned to the plane of cleavage between the device and the substrate, thus allowing to perform the splitting. The splitting can be facilitated by the refinement of the substrate before splitting.
This invention provides various advantages over the currently available other proposed technologies, including the following :
(1) Providing a material with low defect density. The defect density of the end plates is lower than the defect density obtained using currently available technologies, as the density of defects in the original crystal, the seed crystal is comparable to the best available (Al, Ga, ln)N, and these defects continue to annihilate growth bulls.
(2) Ease of arranging the production of the final material and effectiveness on cost of cultivation. When using the method is in growing from the vapor phase, there is no need to use high-pressure apparatus, and from each boules can get a lot of records.
(3) the Possibility of growing plates with a large surface area. Priming with a large area is already available and/or can be obtained as a result of this process, which gives the opportunity to grow boules with a large cross-sectional area. The cross-sectional area boules becomes larger when using larger blades. In addition, the area of the single crystal can constantly increase during the growing, getting larger priming for subsequent cultivation.
(4) Additional degrees of freedom in the choice of the orientation of the substrate. The orientation of the substrate can be selected or optimized for improved epitaxial building or fixtures for use in specific devices. The optimal orientation of the plate can be selected as the orientation on N-plane or Ga-plane and aligned along the main crystallographic axes (for example, a, m or r) or may be slightly inconsistent, to create a surface level for epitaxial growth.
(5) the Ability to adjust the electrical characteristics. Electrical characteristics of the material boules can be adjusted to meet the requirements of application-specific devices that will be designed plates, cut from the boules. The simplified what is doping in comparison with conventional breeding bulls, as the doping is possible to regulate the gas-phase flow, and not the concentration of alloying elements in the melt, which is difficult to control.
(6) the Ability to adjust the compliance of the lattices between the seed crystal and the growing crystal boules by regulating the composition of the alloy according to any predecessor.
Characteristic features and advantages of this invention are more fully shown later, not limiting example, in which all share and percentage compositions are given by weight, except where otherwise noted.
The GaN boules were grown on the seed crystal of GaN using epitaxy from the vapor phase hydride (APPG) in a reactor system of the type shown schematically in figure 2. Ga-containing component was obtained by the interaction of gaseous HCl with molten Ga in ˜850°with the formation of gaseous compounds of gallium chloride. Nitrogen-containing component was provided by gaseous ammonia (NH3).
Bare GaN crystals were obtained by the method APPG/optical Department. The use of nucleating GaN reduces stresses due to mismatch of thermal coefficients of expansion and crystal lattices, and facilitates the growth of long boules without cracking. The crystals-the first seed were treated with active the areas in SiCl 4with the removal of 0.5 micron material, and then cleaned with a solvent and dilute HCl to remove from the GaN surface contamination and native oxide. For best results it is preferable for the polishing of the crystal-nucleating or smooth seeds without treatment. The seed was placed in the reactor APPG and maintained in current NH3until then, until the start of the growth. During the nucleation temperature of the plate was less 993°With, although can be used at higher temperatures. The first attempt used a temperature below the ideal, in order to ensure that the GaN material will not crack. The ratio of flows NH3and HCl during the process was maintained around 35. Demonstrated such a high growth rate as 0.15 mm/h
Was grown bull GaN cross-section of 8 cm2and a length of 4 mm on the GaN seed of irregular shape. Obtained initial results showed that it is possible to grow the GaN boules having a substantially greater length (thickness)than previously reported, without cracking and without appreciable reduction of the chip area of the original seed GaN. Material GaN boules was strong enough that it can be mechanically divided into individual plates. Cutting plates was performed using a wire saw. Litovka about the individual records held by sandblasting, and the end product - the plate was ground on the edge. The polishing plates spent abrasives (diamond) decreasing sizes.
From the original bulls GaN were sequentially made several records. Cut off from the GaN boules plate without further processing had a lateral dimension of about 1.75 inches (44,45 mm), and cut the material of the plate was subjected to polishing and Litovka with getting plates with a diameter of 1 inch (25.4 mm).
The quality of the crystal plates was good. Despite the use of seed material intentionally low quality (gross and eaten), minimal training priming and far from optimal process (growth temperature decreased with increasing Buli), half-width of the peak on the x-ray double crystal (shown in figure 3) for the record GaN obtained from the bulls, made the way APPG amounted to ˜351 arc seconds, which is comparable with heteroepitaxial GaN material of good quality. The background concentration of donors in the first plates are well comparable with other materials APPG, accounting for less than 1016cm-3.
The preceding example demonstrates the reliability of the principle methodology for the manufacture of boules on this invention. The optimal implementation of the method according to this invention may include the use of exactly oshlifovannoj anticipated higher the quality, optimized receiving priming and maintaining a constant temperature growth during cultivation (including abstraction priming ago).
The preceding example demonstrates the following features of the present invention.
Growing from the vapor phase method APPG cultivation was carried out for the deposition of 4 mm material GaN. As growth in the vapor phase is further from equilibrium than in the ordinary methods of volumetric growth, and nitrogen-containing precursor is supplied to the process, eliminates the need for high-pressure apparatus.
The high speed of growth. Demonstrated a growth rate of more than 0.15 mm/h, and a higher growth rate (e.g., 2-4 times higher than shown in this example) is achievable with improved cleavage NH3and higher temperatures growth.
A large area. The cross-section of boules was equal to the cross section of a crystal seed. In the previous example, the size of the seed was limited ˜8 cm2but there are no obstacles to scale this process to the diameters of greater value.
The absence of cracks. Growing on the crystal-nucleating matching the crystal lattice and thermal expansion coefficient, gives the opportunity to grow 4 mm GaN without cracking, which is markedly different from the previous you is asiania on the seed crystal of SiC or sapphire. It was also shown that the growth and cooling occur without stress, because the original cracks in the seed does not spread during the growth bulls (they do not grow in the lateral direction or in the material of new records).
The cut plate. Buhl GaN was strong enough and had sufficient length so that it can be cut into individual plates, which were then litovali and polished to a mirror finish. The resulting plates are highly suitable for processing, epitaxial growth and fabrication of devices.
Good quality material. The quality of the crystal plates was comparable with currently available heteroepitaxial materials GaN.
The preceding example illustrates the advantages and characteristic features of the present invention. Various aspects of the present invention can be optimized, including the following.
Getting the ball rolling. There is an obvious change in the structure of GaN deposited on a seed crystal. Possible optimization obtaining seed and nucleation during growth to achieve the maximum quality of the product - Buli.
The design of the reactor. A reactor for growing preferably be designed and located so as to ensure uniform growth of the GaN boules at high speeds growth, effective management of by-products of ro is that with the constant replenishment of the reactants.
The chip area. Methods preparation of edges combined with higher temperature growth, higher ratios of NH3/Ga, the lower the pressure, the desired temperature gradients and non-uniform profiles of the threads so that the monocrystalline material boules are grown in the direction perpendicular to the seed, and in the direction parallel to the seed, for the extension of the area of the crystal. Alternatively, it is convenient to use the methods of application on the edge of the coating, which serves as a barrier for lateral growth, to limit the growth of polycrystals on the edges boules and spread them on the surface of the single crystal.
Production records. The operation unit production records (polishing, cutting, Litovka, sanded surface, etc. can be optimized (now known limits) to maximize the quality of the product - records obtained from the bulls.
Buhl according to this invention can be split or cut any suitable way to obtain the number of records that are suitable for the manufacture of electronic devices and can then be used as a substrate suitable for fabrication of electronic devices, for the manufacture of a wide range of microelectronic devices and structures that preceded it, such to the to the LEDs, laser diodes, ultraviolet photodetectors, transistors with high electron mobility, bipolar transistors, bipolar transistors with geterosoedineniya, rectifiers high power components division multiplexing wavelengths, etc. Several different types of such devices are described for illustration below.
Figure 4 is a schematic illustration of the double heterostructure light-emitting diode LED 90, made on the plate 92, obtained from the bulls in this invention. The record, which may be alloyed material AIGaN n-type, has on its lower surface electrode 94 n-type. Covering the upper surface of the plate lie successive layers 96-104, including layer 96 coverage of n-AIGaN layer 98 active region of the undoped InGaN covering layer 100 of AIGaN p-type contact layer 102 of GaN p-type and the p-electrode 104.
Figure 5 is a schematic illustration of the laser diode 110 with cleaved facets, made on the plate 112 received from the bulls in this invention. The plate 112 is made of a material AIGaN p-type with a p-contact electrode 114 having a large surface area on its bottom surface. On the upper surface of the plate caused successive layers 116-124, including layer 116 covering of p-AIGaN layer 118 of GaN/lnGaN active area with the bore is alkemi quantum wells, the covering layer 120 of AIGaN n-type contact layer 122 of the GaN n-type and the n-electrode 124.
6 is a schematic illustration of the UV photodetector 130, made on the plate 132 obtained from the bulls in this invention. The plate 132 is formed from a material Alx1Ga1-x1N, where x1>x2+0,05. On a substrate deposited successive layers 134-137, including layer 134 of the material Alx1Ga1-x1N n- - type layer 136 of the material Alx2Ga1-x2N-type n-electrode 137, the layer 138 of insulating (undoped) material Alx2Ga1-x2N, a layer 140 of material Alx2Ga1-x2N p-type layer 142 of the material GaN p-type (or layer, brought to GaN p-type) and p-electrode 144.
7 is a schematic representation of the transistor 150 with high electron mobility, custom polyisocyanat plate GaN 152 obtained from the bulls in this invention. On the surface of the plate 152 is sequentially applied layers 154-158, including non-alloy layer 154 of GaN, undoped layer 156 of AIGaN, which may have a thickness that is less than 100 angstroms, and a layer 158 of n+AIGaN, which may have a thickness of about 200 angstroms. The structure of the device includes a drain electrode 160, a gate electrode 162 and the source electrode 164, as shown.
Fig is a schematic picture the rectifier 180 high power, made on the plate 182 of (AIGaln)N n-type, derived from the bulls in this invention. Under the plate is ohmic contact 184, and on it are the separation layer 186 of (AIGaln)N n-type and the Schottky contact 188.
Fig.9 is a schematic illustration of a bipolar transistor 200 with geterosoedineniya AIGaN/GaN made on the plate 202 of the GaN n-type, derived from the bulls in this invention. The structure of the device includes the collector 204 of GaN n-type collector contact 206, a thin (for example, a thickness of from 100 to 300 nm) base region 208 of the GaN p-type and the base electrode 210. On the base area of the applied emitter 212 of AIGaN n-type and the emitter electrode 214. The connection between the emitter and the base material can be placed gradually from GaN base 208 to connect AIGaN emitter 212, to avoid a sharp break in the conduction band in this connection.
Although the invention is described here with reference to the manufacture and use of bulls as a three-dimensional grown bodies, from which you can make a lot of plates, suitable for the manufacture of microelectronic devices by cutting or separation, it should be understood that the various described methods are applicable to processes for the manufacture of a single plate. For example, a single wafer of GaN can be obtained by growing a thick (e.g. the R, 300-500 microns) layer of GaN on sapphire and subsequent separation of this layer of GaN on a substrate of sapphire, and the obtained GaN layer is a plate for further processing. In this case the additional epitaxial layers can be grown on the surface of the substrate, either in the system APPG before separation from the seed, or at another stage of the process following the removal from the system APPG. Such structures separate plates suitable for influence operations process described various types, including, for example, phase doping, polishing or Litovka.
Although this invention has been variously described herein with reference to illustrative embodiments of the distinctive features, it should be understood that embodiments of the characteristic features described above do not imply limitation of the present invention, and that the experts can offer other changes, modifications and other embodiments of the. Thus, the invention should be construed broadly in accordance with the following claims.
1. Buhl (Al, Ga, ln)N suitable for manufacturing microelectronic devices grown on the seed crystal of the same material, and the bull has a maximum transverse dimension larger than the seed crystal, the ri this bull has a diameter more than 1 cm and a length of more than 1 mm, essentially, has no cracks and has a density of defects on the top surface of less than 107defects/cm2.
2. Buhl according to claim 1, having a density of surface defects is less than 106defects cm-2.
3. Buhl according to claim 1, having a density of surface defects is less than 104defects cm-2.
4. Buhl according to claim 1, grown on the seed crystal having an orientation selected from the group consisting of C-axis, a-axis, m-axis and r-axis orientation with a cutoff of 1 to 10° from the main axis of the crystal, N-face and (ln, Al, Ga)-face.
5. Buhl according to claim 1, in which the nitride (Al, Ga, ln) includes AlGaN.
6. Buhl according to claim 1, in which the nitride (Al, Ga, ln) includes GaN.
7. Buhl according to claim 1, alloyed by diffusion at temperatures above 600°C.
8. Buhl according to claim 1, grown on the seed crystal obtained by the method of optical branches.
9. Buhl according to claim 1, grown on the seed crystal obtained by growing the (Al, Ga, ln)N on the sacrificial matrix, and removing the matrix using the removal method selected from the group consisting of physical methods, thermal methods, methods of etching, N-fracture and removal by embrittlement.
10. Buhl according to claim 1, having a cross sectional area greater than 5 cm2.
11. Buhl on p. 10, having a length of more than 5 mm
12. Buhl according to claim 1, grown by the method of vapor-phase epitaxy.
13. Buhl according to claim 1, having the length is more than 4 mm
14. Buhl according to claim 1, having a length of more than 10 mm
15. Buhl according to claim 1, in which the seed crystal of the same material has an orientation selected from the group consisting of C-axis, a-axis, m-axis and r-axis, and the cut of less than 10° relative to the main axis of the crystal.
16. Buhl according to claim 1, grown on N-face or (Al, Ga, ln) - faces oriented along the C-axis of the seed crystal.
17. Buhl according to claim 1 that is n-type.
18. Buhl according to claim 1, alloy substance alloying agent selected from the group consisting of silicon and germanium.
19. Buhl under item 18, in which the substance of alloying of silicon from silane.
20. Buhl under item 18, in which the substance of alloying - Germany - from tetrahydride Germany.
21. Buhl according to claim 1, alloyed to obtain the concentration of electrons at room temperature for about 1·1015approximately 3·1019cm-3.
22. Buhl according to claim 1, alloyed to obtain the electron concentration at room temperature of from about 5·1017about 1·1019cm-3.
23. Buhl according to claim 1, the p-type.
24. Buhl on item 23, alloy substance alloying agent selected from the group consisting of beryllium, magnesium and zinc.
25. Buhl on point 24, alloy using ORGANOMETALLIC source substance alloying elements.
26. Buhl on item 23, alloy for procedurecentral holes at room temperature for about 1· 1015about 1·1019cm-3.
27. Buhl on item 23, alloy to obtain the concentration of holes at room temperature about 5·1017about 1·1019cm-3.
28. Buhl according to claim 1, alloy substance alloying agent selected from the group consisting of vanadium, chromium, iron, arsenic, magnesium, cobalt, Nickel and copper.
29. Buhl on p, alloy using a vapor source substance alloying elements.
30. Buhl on p, in which the substance of the alloying additive is produced from a solid source selected from the group consisting of solid sources of alloying p-type and alloying deep level.
31. Buhl on p having a resistivity higher than 1·103Om-see
32. Buhl (Al, Ga, ln)N, including the seed crystal of the same material and the material boules grown on the intermediate layer between the specified material of the seed and the specified material boules, and specified Buhl has a maximum transverse dimension of cross-section area greater than that of the material of the seed.
33. Buhl on p, in which the material of the intermediate layer has a functional purpose, at least one of the following: reduction or adaptation of the voltage of the source material for the record, the change of the electric characteristics of the original material the material for the plate, the decrease in the density of defects in the source material for the plate, facilitating the separation of the source material for the plate material of the seed and facilitating the nucleation during the growth of the source material for the record.
34. Buhl on p, in which the intermediate layer caused by the application method selected from the group consisting of vapor-phase epitaxy, chemical vapour deposition, physical vapour deposition, molecular beam epitaxy, epitaxy from the vapor phase ORGANOMETALLIC compounds and epitaxy from the vapor phase hydride.
35. Buhl on p, in which the intermediate layer is formed by modification, etching or profiling of the seed crystal.
36. Buhl on p, in which the intermediate layer consists of one or more layers of materials.
37. Buhl or vinyl nitride (Al, Ga, ln), alloy using the process of nuclear transformation.
38. Buhl or plate on clause 37, alloy to obtain the electron concentration at room temperature of 1·1015up to 5·1019cm-3.
39. Record received from boules according to claim 1, alloyed by diffusion at temperatures above 600°C.
40. Record received from boules according to claim 1.
41. Plate on p having an orientation selected from the group consisting of C-axis, a-axis, m-axis, r-axis.
42. Plates is and p, with the orientation of the slice from 0.5 to 10° from the main axis of the crystal.
43. Plate on p having at least one of the N-face and (Al, Ga, ln) - faces oriented along the C-axis of the plate, prepared for epitaxial growth.
44. Plate on p separated from the seed crystal of the same substance in a manner other than cutting or cutting on the plate.
45. Plate, separated from the bulls, containing successive layers of material of the plate and the separating material, and separating this material largely absorbs the selected radiation than the material of the plate, and the plate is separated from the bulls by exposure of specified selected radiation to the specified separating material.
46. Record of GaN, suitable for the manufacture of electronic devices made of GaN boules where the specified Buhl GaN grown from the seed crystal of the same material, and where the bull has a maximum size with a higher cross-section than the seed crystal.
47. Plate on p.46, having a surface roughness, providing a standard deviation of less than 5 angstroms in the area of 10×10 μm2.
48. Plate on p.46, having a radius of curvature of more than 1 m
49. Plate on p.46, having a plane oriented rather than ± 0,3°.
50. The record is .46, having a plane that is obtained by the splitting.
51. Plate on p.46, with the total deviation in thickness of less than 20% of the average thickness of the plate.
52. Plate on p.46, with the total deviation in thickness of less than 5% of the average thickness of the plate.
53. Plate on p.46 with distortion less than 50 μm2.
54. Plate on p.46 with distortion less than 10 μm2.
55. Record at item 46, further comprising a microelectronic device structure in it or on it.
56. Plate on p.46, in which the structure of a microelectronic device is selected from the group consisting of LEDs, laser diodes, ultraviolet photodetectors, transistors with high electron mobility, bipolar transistors, bipolar transistors with geterosoedineniya, copying components to separate wavelengths and rectifiers high power.
57. The method of manufacture of boules (Al, Ga, ln)N, including the provision of seed crystal for the bulls of the same material; and growing material (Al, Ga, ln)N on the seed crystal in the direction perpendicular to the specified seed crystal, and in a direction parallel to the specified seed crystal, by epitaxy from the vapor phase, to obtain the specified boules, so that this bull had a maximum size greater is the horse of the cross-section, than the seed crystal.
58. The method according to § 57, in which the specified operation of the cultivation is carried out at a growth rate of more than 20 μm/h
59. The method according to § 57, in which the specified operation of the cultivation is carried out at a growth rate of more than 50 μm/h
60. The method according to § 57, wherein said material (Al, Ga, ln)N comprises GaN, and the growth is carried out at a temperature in the range of from about 900 to about 1100°C.
61. The method according to § 57, wherein said material (Al, Ga, ln)N includes AIN, and the growth is carried out at a temperature in the range of from about 950 to about 1200°C.
62. The method according to § 57, wherein said material (Al, Ga, ln)N includes InN, and the growth is carried out at a temperature in the range of from about 700 to about 900°C.
63. The method according to § 57, in which the specified epitaxy from the vapor phase includes epitaxy from the vapor phase hydride.
64. The method according to § 57, in which the cultivation of the material (Al, Ga, ln)N on the seed crystal comprises applying a reagent source of nitrogen selected from the group consisting of ammonia, hydrazine, amines and polyamines.
65. The method according to § 57, in which the cultivation of the material (Al, Ga, ln)N on the seed crystal includes the ratio of the flow of the nitrogen-containing precursor to the flow of the precursor containing an element of group III, the flow rate of nitrogen-containing precursor is substantially greater than the speed of p is the current predecessor, containing an element of group III.
66. The method according to § 57, in which the cultivation of the material (Al, Ga, ln)N on the seed crystal includes a flow ratio of nitrogen-containing precursor to the flow of the precursor containing an element of group III in the range of from about 10 to about 1000.
67. The method according to § 57, in which the cultivation of the material (Al, Ga, ln)N on the seed crystal includes the introduction of liquid solution containing the precursor with an element of group III and an element of group V in the reactor for the cultivation and implementation of the breeding material of the nitride III-V groups in the specified reactor for growing.
68. The method according to § 57, in which during the breeding bird pushed from the sources of their respective predecessors material (Al, Ga, ln)N.
69. The method according to § 57, in which the bull during growth push from sources appropriate precursors for the material (Al, Ga, ln)N in order to maintain a preset distance between the surface of the growth bulls and the specified source.
70. The method according to § 57, in which grow the bull longer than 1 mm.
71. The method according to § 57, in which grow the bull longer than 4 mm.
72. The method according to § 57, in which grow the bull with length more than 10 mm
73. The method according to § 57, in which the bull is grown, at least up until the defect density on the surface of the growth will not be men who e 10 7defects cm-2.
74. The method according to § 57, in which grow the bull with cross-sectional dimension of more than 1 cm
75. The method according to § 57, in which grow the bull with the cross-sectional area of at least 5 cm2.
76. The method according to § 57, in which the seed crystal has an orientation selected from the group consisting of C-axis, a-axis, m-axis, r-axis, and the section is deviating from the main axis of the crystal is less than 0.5°.
77. The method according to § 57, in which the seed crystal has an orientation of a cut from 0.5 to 10 degrees from the main axis of the crystal.
78. The method according to § 57, in which the growth of boules carried out on N-face or on the (Al, Ga, ln) - faces oriented along the C-axis of the seed crystal.
79. The method according to p. 57, in which the bull is grown on the seed crystal obtained from the GaN boules.
80. The method according to § 57, in which the seed crystal obtained by the method of epitaxy from the vapor phase hydride/optical branch.
81. The method according to § 57, in which the material (Al, Ga, ln)N is grown on the seed crystal, get growing (Al, Ga, ln)N on the sacrificial matrix and the removal of this matrix removal method selected from the group consisting of ways to remove physical, thermal methods, methods of etching, N-fracture and embrittlement.
82. The method according to § 57, in which the material (Al, Ga, ln)N is grown, at least one intermediate layer between which the seed crystal and the material of the nitride.
83. The method according to p. 82, in which at least one intermediate layer is precipitated by a method selected from the group consisting of vapor-phase epitaxy, chemical vapour deposition, physical vapour deposition, molecular beam epitaxy, epitaxy from the vapor phase ORGANOMETALLIC compounds and epitaxy from the vapor phase hydride or otherwise forming it into the seed crystal or with his help.
84. The method according to § 57 contains an inclusion of an impurity to control the quality of the crystal or polytype material (Al, Ga, ln)N during its cultivation.
85. The method according to § 57, further comprising doping material (Al, Ga, ln)N substance alloying agent selected from the group consisting of vanadium, chromium, iron, arsenic, manganese, cobalt, Nickel and copper.
86. The method according to claim 57, in which the cultivation of the material (Al, Ga, ln)N is carried out with a source of replacement sources of components for material (Al, Ga, ln)N, maintaining distance from the source to the bulls during the breeding and growth rate of the material (Al, Ga, ln)N exceeding 20 μm/h
87. The method according to p carried out in a period of time sufficient to grow the material of the nitride of the element III-V group to a thickness more than 4 mm
88. The method according to p. 57, further comprising receiving from the bulls record.
89. The method according to p, in which the vinyl floor is up by cutting the bulls with a wire saw.
90. The method according to p, further comprising the operation of forming plates selected from the group consisting of drilling, processing a stream of abrasive material, slicing with a wire saw, laser processing, mechanical-chemical polishing, photoelectrochemical etching and etching the active ions.
91. The method according to p, further comprising processing the records to obtain the standard deviation of roughness of less than 10 angstroms square plates 10×10 μm2.
92. The method according to p, further comprising processing the plate to remove the damaged surface layer.
93. The method according to p, including additional production on this record patterns microelectronic device.
94. The method according to p. 93, in which the structure of the device includes at least part of a device selected from the group consisting of LEDs, laser diodes, ultraviolet photodetectors, bipolar transistors, bipolar transistor with a heterostructure, transistors with high electron mobility, rectifiers high power and components for division multiplexing wavelengths.
95. The method according to p, in which the bull is subjected to Litovka before manufacture from her plate.
96. The method according to p, in which the material (Al, Ga, ln)N contains GaN.p> 97. The method according to p, further comprising polishing plate.
98. The method according to p, additionally including a grinding plate for coarse and medium abrasive means followed by polishing a thin abrasive tool.
99. The method according to p in which abrasive tool includes at least one abrasive material selected from the group consisting of diamond, boron carbide, silicon carbide and aluminum oxide.
100. The method according to p, optionally including mechanochemical polishing plate composition in the form of a suspension selected from the group comprising acidic suspension for mechanochemical polishing and basic suspension for mechanochemical polishing.
101. The method according to p, further comprising etching the active ions, at least one face of the plate receiving surface suitable for epitaxial growth.
102. The microelectronic device structure including a substrate, obtained from the bulls according to claim 1, and having a device constructed on and/or in the substrate.
103. The structure of microelectronic devices by p. 102, in which the device is selected from the group consisting of LEDs and lasers.
104. The structure of microelectronic devices by p. 102 in which a substrate is GaN.
105. The structure of microelectronic devices by p. 104, where GaN is freely located is its material.
FIELD: ferroelectric or electret memorizing contour (C) .
SUBSTANCE: ferroelectric or electret memorizing contour has memory cell with ferroelectric or electret memorizing material, and two electrodes, while one of electrodes has at least one functional material, capable of physical and/or chemical incorporation of atomic or molecular particles in its volume, aforementioned particles contained in electrode or in memorizing material of memory cell.
EFFECT: increased resistance to wear: minimization of wear processes in memorizing devices, based on organic and, in particular, polymer electrets and ferroelectrics.
2 cl, 11 dwg
FIELD: electronic industry, applicable in manufacture of high-power semiconductor devices and high-power integrated circuits, hybrid ones inclusive; the invention is mainly oriented to the assembly of high-power integrated circuits in metal-glass and metal-ceramic casings.
SUBSTANCE: the circuit leads are soldered by the group method and their main part is positioned on the same side on which the crystal is positioned, the preset remoteness of the free ends of the leads from the board is provided, in the process of soldering the variation of the distance between the components being soldered is controlled, on one installation designed for soldering out of inner conductors with a definite cross-sectional area, and/or on one installation designed for soldering of boards, and/or on one installation for soldering of crystals during one production cycle effected is respectively the soldering out of the inner conductors and/or soldering of boards, and/or soldering of crystals of various circuits, the possibility of simultaneous delivery of semifinished items different in type and/or class of the circuits is provided.
EFFECT: provided economically effective limited pliable production of high-power integrated circuits of a wide range.
FIELD: solar light sources.
SUBSTANCE: proposed solar cell noted for high effectiveness of more than 5% has first light accumulating circuit incorporating first substrate that carries first electrode and layer of light-accumulating bars electrically connected to first electrode. Each of light-accumulating bars incorporates polymer of formula(I): X1 - (Xm + 1)m, (I) where m is at least 1 and may constitute from two, three, or four to 20 and more; X1 is charge separation group (and preferably porphyrinic monocycle that may be, essentially, one ligand of double-tier sandwich compound) in excited state with energy equal to or lower than that of X2; and groups of X2 to Xm + 1 are, essentially, chromophores (and again , they are preferably porphyrinic monocycles).
EFFECT: reduced thickness and weight of portable flexible solar cells.
25 cl, 58 dwg
FIELD: computer vision engineering; photodetectors, thermal imagers, infrared radiometers, and various sensors of computerized control devices.
SUBSTANCE: novelty in proposed device is that resistive photosensors are made of heteroepitaxial layers of different forbidden gap. Circuit set up of compensating charge capacitor connected to its potential recovery switch is connected to each integrating capacitor and through series-connected compensation addressing switch and feedback switch, to circuit transferring charge portion from charge compensating capacitor to integrating capacitor. Connected to each amplifier integrating capacitor is comparator whose output is connected to gate electrode of feedback switch and to complementing input of counter-register each of whose bits is connected to array of memory locations controlled by circuit affording exchange of addresses between counters and memory, data write and read buses of data on their transfer from counter to memory and vice versa. Memory locations are connected to counter-register bits. Device has memory readout addressing circuit and multiplexed readout buses for transferring digital data to digital outputs.
EFFECT: enhanced sensitivity and dynamic range.
17 cl, 2 dwg
FIELD: electrically programmable nonvolatile memory devices implemented by using microtechnology and nanotechnology methods.
SUBSTANCE: proposed memory array location that possesses both electrically programmable nonvolatile memory item properties and rectifying properties with characteristics providing for electrical isolation of location in array without enlarging its size has first-layer conducting bus disposed on substrate that electrically insulates it from other first-layer conducting buses of array; second-layer conducting bus intersecting first-layer conducting bus; insulating layer, 3 to 100 nm thick, separating first- and second-layer buses; insulating slot in the form of open end of insulating layer in vicinity of intersection of first-layer buses and edges of second-layer ones; variable-conductance material which is placed in insulating slot and changes its conductivity as electron flow is passed through this material; and medium above insulating slot surface affording exchange of variable-conductance material particles. Conducting bus of one of layers is made of p or n semiconductor.
EFFECT: enlarged functional capabilities.
6 cl, 12 dwg
FIELD: semiconductor integrated circuits for building photosensitive digital and analog devices.
SUBSTANCE: circuit set up of two photodiode elements 1, 2 has recovering MOS transistor 3 whose drain is connected to power bus E and source, to input of source follower built around two transistors 12, 13; connected in addition in each element are coupling gates 4, 7, storage gates 5, 8, and transmission gates 6, 9 which are charge intercoupled within each element and charge coupled with photodiodes 1, 2; there is also n+ region 10, 11 connected to power bus E and charge coupled with transmission gate 6, 9; storage gates of two elements are interconnected and connected to source of transistor 3; coupling and transmission gates 4 and 6 of one element, respectively, are connected to transmission and coupling gates 9 and 7, respectively, of other element; coupling gate 4 of one element is connected to gate of transistor 3.
EFFECT: provision for analog subtraction of image signals of two adjacent elements.
1 cl, 2 dwg
FIELD: computer engineering and integrated-circuit electronics.
SUBSTANCE: proposed integrated-circuit field-effect transistor designed for use in very large-scale integrated circuits incorporates provision for high mobility of electrons in channel at their high concentration, as well as for ensuring pentode output characteristics of short-channel transistor enabling the development of integrated-circuit logic gates around it thereby implementing three processing-compatible alternatives of transistors having different transfer current-voltage characteristics. Newly introduced in proposed integrated-circuit field-effect transistor that has semi-insulating GaAs substrate, semiconductor GaAs layer of inherent polarity of conductivity, semiconductor AlGaAs layers, metal gate, semiconductor drain and source layers of second polarity of conductivity, drain and source metal contacts, semiconductor drain and source layers of second polarity of conductivity are semiconductor GaAs layer of inherent polarity of conductivity, semiconductor AlGaAs layers of inherent polarity of conductivity, semiconductor AlGaAs layer of second polarity of conductivity, highly doped semiconductor gate region of second polarity of conductivity, all enabling use of dimensional energy quantization and energy layer displacement from quantum well.
EFFECT: enhanced speed, reduced rate of degradation of transistor characteristics, and enhanced effectiveness of its use in integrated circuits.
1 cl, 8 dwg
FIELD: semiconductor integrated circuits; photosensitive digital and analog photodetectors.
SUBSTANCE: circuit of CMIS photodetector incorporates photosensitive gate and following control MIS transistors: recovery transistor whose drain is connected to power bus and source, to input of source follower built around two transistors; coupling transistor whose source contacts photosensitive gate channel; source of recovery transistor is connected to photosensitive gate and drain of coupling transistor, to additional power supply. Control pulses arriving at input of recovery transistor and gate of coupling transistor provide for extraction of charges of two adjacent frames from photosensitive gate channel.
EFFECT: ability of separating image moving fragments in focal plane of chip due to using frame-to-frame subtraction.
1 cl, 2 dwg
FIELD: vacuum and solid state electronics.
SUBSTANCE: proposed method involves use of semiconductor substrate having plurality of micropoints disposed according to vacuum integrated circuit layout. Conductor and insulator plasma streams are alternately conveyed to substrate. Conductor plasma stream is produced by exciting series of pulsed vacuum arcs of length τ and space T between plasma generator cathode and anode. Insulator plasma stream is produced by injecting reactive gas. Atoms and ions whose energy in transport is over eU2 are removed from conductor and insulator plasma streams. Potential barrier of eU2 < eU1 is formed above end of each of plurality of micropoints for insulator plasma ions and for conductor plasma ions whose energy is lower than eU2 in the form of plurality of closed equipotential surfaces of potential U2. Insulator plasma and conductor plasma are condensed on external end of equipotential surfaces and plurality of closed spaces whose shape is dictated by shape of closed equipotential surfaces are used as bulbs of electronic valves.
EFFECT: facilitated manufacture of vacuum integrated circuits due to dispensing with etching and lithographic operations; improved quality of products.
21 cl, 13 dwg
FIELD: electronic engineering.
SUBSTANCE: proposed substance related to materials acting on electromagnetic fields so as to control and change them and can be used for producing materials with preset optical, electrical, and magnetic characteristics has in its composition active-origin carrier in the form of clusters of atoms, nanoparticles, or microparticles, its insulating function being checked in the course of manufacture; this function is characteristic controlling interaction between substance and electromagnetic field.
EFFECT: improved characteristics of heterogeneous substance.
FIELD: microelectronics; methods of manufacture of microcircuit chips.
SUBSTANCE: the offered invention is pertaining to the field of microelectronics, in particular, to the methods of manufacture of microcircuit chips. The offered method includes a loading of semiconductor slices in a reactor having hot walls perpendicularly to a gas stream, pumping-out of the reactor air up to the ultimate vacuum, introduction of monosilane for deposition of layers of polycrystalline silicon, silane supply cutoff, pumping-out of the reactor air up to the ultimate vacuum, delivery of a noble gas into the reactor up to atmospheric air pressure, unloading of the semiconductor slices from the reactor. After introduction of the noble gas into the reactor conduct an additional thermal annealing of layers of polycrystalline silicon at the temperature of no less than 1323K, then keep the slices at this temperature during 40-60 minutes in a stream of noble gas and reduce the temperature down to the temperature of the polycrystalline silicon layers growth. The technical result of the invention is a decrease of heterogeneity of resistance of the polycrystalline silicon layers.
EFFECT: the invention ensures a decrease of heterogeneity of resistance of the polycrystalline silicon layers.
1 dwg, 2 tbl, 1 ex
FIELD: metal science; protection of materials against external and corrosive attacks.
SUBSTANCE: proposed method for producing diamond-like films designed for encapsulating solar photocells to protect them against chemical, radiation, and mechanical damage includes variation of ion kinetic energy, plasma discharge current, and spatial density distribution of plasma incorporating C+, H+, N+, and Ar+ ions by acting upon ion current from radial source with electric field built up by stop-down, neutralizing, and accelerating electrodes. Spatial plasma distribution is checked for uniformity by measuring plasma current density on solar photocell surface whose temperature is maintained not to exceed 80 oC. In the process substrate holder makes complex axial movement in three directions within vacuum chamber. Diamond-like films produced in the process on solar photocell surface area over 110 cm2 are noted for uniformity, difference in their optical parameters variable within desired range is not over 5%.
EFFECT: enhanced adhesive property, microhardness, and resistance of films to corrosive attacks.
5 cl, 12 dwg, 2 tbl