Method for manufacture of powerful uhf transistor

FIELD: electrical engineering.

SUBSTANCE: method for manufacture of a powerful UHF transistor includes formation of the topology of at least one transistor crystal on the semiconductor substrate face side, formation of the transistor electrodes, formation of at least one protective dielectric layer along the whole of the transistor crystal topology by way of plasma chemical application, the layer total length being 0.15-0.25 mcm, formation of the transistor crystal size by way of lithography and chemical etching processes. Prior to formation of the transistor crystal size, within the choke electrode area one performs local plasma chemical etching of the protective dielectric layer to a depth equal to the layer thickness; immediately after that one performs formation of protectively passivating dielectric layers of silicon nitride and diozide with thickness equal to 0.045-0.050 mm; plasma chemical application of the latter layers and the protective dielectric layer is performed in the same technological modes with plasma power equal to 300-350 W, during 30-35 sec and at a temperature of 150-250°C; during formation of the transistor crystal size ne performs chemical etching of the protectively passivating dielectric layers and the protective dielectric layer within the same technological cycle.

EFFECT: increased power output and augmentation ratio or powerful transistors with their long-term stability preservation.

4 cl, 1 dwg, 1 tbl

 

The invention relates to electronic devices, and in particular to methods of manufacturing of the power of microwave transistors based on semiconductor materials of group AIIIBVand heterostructures based on them, and monolithic integrated circuits (MIC).

In the manufacture of these semiconductor devices one of the main objectives is to provide high output power and at the same time long-term stability of electrical characteristics.

One of the keys to long-term stability of electrical characteristics of semiconductor devices is the provision of a high voltage breakdown. While providing the latter plays an important role protecting the surface elements of semiconductor structures in the process of their manufacture, and are, as a rule, by means of dielectric materials (hereinafter dielectric films or dielectric layers).

The latter should be different, first of all:

- high voltage breakdown

- small dielectric loss (tangent of dielectric loss angle),

- high chemical and thermal stability.

These characteristics dielectric films are defined as the material of the dielectric films, their structure and method of manufacture.

The quality properties of the interface metal-insulator-floor is Robotnik along with other boundary conditions of semiconductor structures determine the electrical characteristics of semiconductor microwave devices, including the breakdown voltage and leakage current.

A method of obtaining dielectric films of boron nitride on substrates of semiconductor material of type AIIIBV(hereinafter, a semiconductor material), as a result of interaction of borazole and helium in terms of RF-discharge at a temperature of semiconductor substrate 160-200°C [1].

Dielectric films of boron nitride have high chemical and thermal stability.

The disadvantage of this method is the contamination of the dielectric film of carbon and as a consequence, deterioration of the electric characteristics of semiconductor devices and, accordingly, decrease the output power and gain, and reduce their long-term stability.

A known method of manufacturing semiconductor devices and integrated circuits (options), providing for the formation of at least one thin layer of dielectric material film by means of plasma chemical deposition [2].

These carried out with the use of microwave plasma stimulation under conditions of electron cyclotron resonance (ECR) with radio-frequency offset (hereinafter voltage avtomashine) a semiconductor substrate in a plasma source with a resonant volume of the reactor at a frequency of 2.45 and to 1.23 GHz with a magnetic system is mine. The latter creates a magnetic field on the inner cut of a quarter-wave input window of microwave radiation on the longitudinal axis of the source with a magnetic induction of 910-940 GS, and on the longitudinal axis of the source in its Central part on a length of at least 3 cm - 875 Gauss. This ensures the homogeneity of the fashion of the plasma discharge with the inhomogeneity of the plasma density on the cross section of the source is less than 3 percent.

The dielectric film may be formed of a dielectric material is polyimide, and/or silicon nitride, and/or oxynitride silicon.

The semiconductor structure may represent an uncooled barometrically matrix, or microwave transistor, or integrated circuit microwave.

Indicates that the application of electron cyclotron resonance when forming the protective dielectric film of silicon nitride in the fabrication process of semiconductor structures - transistor UHF performed on gallium arsenide, allows to increase the output power at a frequency of 10 GHz 10 to 16 dB, the efficiency from 20 to 42 percent.

However, the dielectric films differ as high mechanical low internal mechanical stress, low porosity and high electrical characteristics, high breakdown voltage, low leakage currents.

However, the experimental the quarterly set, what is the immediate impact of the mode of plasma chemical deposition and especially microwave when forming the protective dielectric film on the surface of semiconductor structures, such as the above-mentioned transistor microwave, leads to violation of the semiconductor structure and the result is:

first, a sharp drop in current flow (operating current) up to 40-100 percent and, accordingly, power dissipation,

secondly, a drop in breakdown voltage depending on the magnitude of the voltage avtomashine that occur at the electrodes of the working chamber plasma-chemical deposition.

This shows a sharp deterioration and possible degradation of the electric characteristics of semiconductor structures.

It should be noted that the above effects of high-frequency and especially microwave plasma is especially evident when forming the protective dielectric film on the semiconductor materials of the type AIIIBV.

This clearly highlights three areas of occurrence of violations in a semiconductor structure monolithic integrated circuits on gallium arsenide (GaAs):

the voltage avtomashine less than 40 B corresponding to the minimum violations;

- transition region voltage avtomashine equal to 40-80 B, the corresponding is the th increase voltage breakdown;

and the field voltage avtomashine more than 80 B, suitable for large voltage breakdown.

Changes in the breakdown voltage of a semiconductor material gallium arsenide occur already in the first minute of plasma chemical deposition and then stabilize for each voltage avtomashine. Moreover, they occur even at low voltages avtomashine, less than 10 B.

Have that on the one hand by itself dielectric film manufactured by plasma-chemical deposition, high mechanical and electrical properties, and on the other hand leads to disruption of semiconductor structures up to their complete degradation.

Moreover this method is technologically difficult.

A known method of manufacturing a powerful microwave transistor, comprising forming on the front side of the semiconductor substrate topology, at least one transistor crystal by means of lithography processes, the formation of electrodes of the transistor by means of a sputtering system metals, forming ohmic contacts in the area of the electrodes of the source and drain and a potential barrier in the region of the gate electrode, forming at least one protective dielectric layer over the entire topology of the transistor crystal by a plasma chemical deposition, the total thickness of 0.15-0.25 μm forming die size transistor through processes of lithography and chemical etching of the protective dielectric layer.

In which, to increase the output power, on the front and back side of the semiconductor wafer opposite to each other to form grooves with predetermined dimensions. It is possible to increase the reproducibility of the size of the crystals and thereby reduce the tolerances during installation and thereby reduce the loss of the microwave in the supply chains and as a consequence, to increase power output.

Moreover, the protective dielectric layer with a thickness of 0.15-0.25 μm, which is sufficiently thick, and used in this invention provides sufficient long-term stability of output power and gain (hereinafter output parameters UHF) power transistors.

However, on the other hand, as shown by the experiment indicated a thick protective dielectric layer introduces significant loss microwave, which limits further opportunities from the viewpoint of further increasing the output power and gain.

The technical result of the invention is to increase the output power and gain powerful microwave transistors by reducing the losses of the microwave leakage currents, and increase the breakdown voltage, while maintaining long-term stability of these output parameters of the microwave.

This technical result is achieved by the method of manufacturing of the power transistor UHF, including the guide formation on the front side of a semiconductor substrate topology, at least one transistor crystal by means of lithography processes, the formation of electrodes of the transistor by means of a sputtering system metals, forming ohmic contacts in the area of the electrodes of the source and drain and a potential barrier in the region of the gate electrode, forming at least one protective dielectric layer over the entire topology of the transistor crystal by a plasma chemical deposition, the total thickness of 0.15-0.25 μm, the formation of die size transistor through processes of lithography and chemical etching.

In which

prior to forming the crystal size of the transistor in the region of the gate electrode is conducted additionally local plasma etching of the protective dielectric layer to a depth equal to its thickness,

and directly next carry out the formation of a protective passivating dielectric layers by means of plasma-chemical deposition of a direct sequence system of dielectric layers of nitride and silicon dioxide thickness equal to each 0,045-0,050 μm,

moreover, chemical finishing and protective dielectric layer is carried out at the same technological modes - when the power of the plasma 300-350 watts, for 30-35 at a temperature of 150-250°C,

in case of formation of crystal size transitoriented chemical etching protective passivating dielectric layer and the protective dielectric layer and in a single technological cycle.

As a semiconductor substrate using gallium arsenide or heterostructures based on it.

When forming die size transistor using chemical or plasma etching.

Protective pestiviruses dielectric layers applied over the entire topology of the transistor or in the area of the electrode of the gate.

Disclosure of the invention.

The essential features of the claimed method of manufacturing of the power transistor UHF and their combination will provide:

Carrying out before forming die size transistor additional local plasma-chemical etching in the area of the gate electrode protective dielectric layer to a depth equal to the thickness of 0.15-0.25 μm), which, as mentioned above, is sufficiently thick to provide the complete removal of this thick protective dielectric layer in the region of the gate electrode, and thus provides a significant reduction in losses microwave and, as a consequence, the increase of output power and gain.

Formation for the entire topology of the transistor crystal or in the area of the gate electrode protective passivating dielectric layers in the form of a direct sequence system of dielectric layers of silicon nitride and silicon oxide in combination with the specified thin, their thickness (equal to each 0,0450,050 microns) will provide:

Firstly, optimum:

(a) the necessary and sufficient protection of elements of the semiconductor structure, the electrodes of the shutter, but compared to the prototype through the dielectric layer (system mentioned dielectric layers), as mentioned above, a much smaller thickness,

b) loss of the microwave.

And, as a consequence of both, the increase of output power and gain, while maintaining their long-term stability.

Secondly, thanks to the combination of this direct sequence system thin dielectric layers of nitride and dockside silicon, namely due to their boundary properties on a dielectric-semiconductor generates them exactly opposite in sign to the elastic stresses (silicon nitride - tensile, and silicon dioxide compressive), and thus provides virtually complete elimination (mutual damping of the elastic stresses in the semiconductor substrate structure, introduced to her by a dielectric layer of silicon nitride and, as a consequence, the increase of output power and gain, while maintaining their long-term stability.

Thirdly, due to the properties of the dielectric layer of silicon dioxide, namely

and the last has a small dielectric loss,

b) almost completely clear out the AET" through vertical growth defects in the protective passivating dielectric layers (direct sequence system of dielectric layers of nitride and silicon dioxide).

And, as a consequence of both, additionally increase the output power and gain, while maintaining their long-term stability.

Use in forming protective and passivating dielectric layers of plasma-chemical deposition, in conjunction with specified its technological regimes, as well as the use of these processing modes when applying the protective dielectric layer, will reduce the temperature of the coating as thin dielectric layers of nitride and silicon oxide, and a protective dielectric layer and thereby will provide:

first, optimal protection of elements of the semiconductor structure while maintaining their integrity,

secondly, the reduction of porosity themselves dielectric layers, and, consequently, improving their quality,

thirdly, obtaining dielectric layers close to the stoichiometric composition and respectively having the minimum number of unwanted impurities.

Both will provide the fabrication of dielectric layers with high mechanical and electrical properties (high breakdown voltage and low leakage currents) and, as a consequence, additionally increase the output power and gain, while maintaining their long-term stability.

<> Thus, the set of essential features provide a full technical result, namely the increase of output power and gain powerful microwave transistors while maintaining their long-term stability.

The invention is illustrated in the drawing.

In the drawing given topology declared powerful microwave transistor, where:

- semiconductor substrate - 1,

- topology, at least one transistor crystal - 2,

- electrodes of the transistor, the ohmic contacts in the area of the electrodes of the source and drain 3 and 4, respectively, and a potential barrier in the area of the electrode of the slide 5,

- protective dielectric layer 6,

- protective-piscivorous dielectric layers in the form of a direct sequence system, a thin dielectric layer of nitride and silicon dioxide 7 and 8 respectively.

Specific the actual powerful transistor microwave.

Example 1.

On the front side of the semiconductor substrate 1, for example, of gallium arsenide with a thickness of 520 μm form:

topology, at least one transistor crystal 2 by means of known processes of lithography,

- electrodes of the transistor crystal by vacuum deposition (industrial installation Ohr-042) system metal (eutectic alloy of AuGe-Ni-Au thickness, 0.3, 0.1 and 0.3 μm, respectively), which form ω is ical contacts in the area of the electrodes of the source 3 and drain 4 and (Ti-Al-Ti, thickness equal to 0.05, 0.5, and 0.1, respectively) - a potential barrier of a Schottky in the area of the gate electrode 5,

- protective dielectric layer 6 by plasma-chemical deposition (industrial installation ND200R) when plasma power 325 W within 35 seconds, at a temperature of 200°C silicon nitride over the entire topology of the transistor crystal thickness equal to 0.20 μm,

- then hold in the area of the gate electrode 5 additional local plasma etching of dielectric protective layer 6 in the buffer etching solution composition HF:NH4F:H2O (1:10:68, OBC respectively) to a depth equal to the thickness of 0.20 μm),

- then hold the formation of a protective passivating dielectric layer by applying a direct sequence system layers of nitride and silicon dioxide thickness equal to each 0,047 μm by plasma-chemical deposition (industrial installation ND200R) when plasma power 325 W within 35 seconds, at a temperature of 200°C,

- form die size transistor through a lithography method and a sequential chemical etching protective passivating dielectric layer and a protective dielectric layer in the buffer etching solution composition HF:NH4F:H2O (1:10:68 OBC respectively) in a single technological cycle.

Examples 2-12.

Analogously to example 1 manufacture is Owlery samples of high-power transistor UHF, but when other process parameters (examples 2-3), and on another semiconductor substrate, heterostructures type:

GaAs-AlxGa1-xAs-InyGa1-yAs-GaAs (MEMT) (examples 5-7)

GaAs-AlxGa1-xAs-InyGa1-yAs-AlxGa1-xAs-GaAs (DPHEMT) (examples 9-11)

and the samples made according to the method prototype (example 4, 8, 12, respectively).

On the manufactured samples of high-power microwave transistors were measured:

- output power microwave (Po.and determined by the gain (Ky),

- conducted analysis for the stability of these output parameters of the microwave.

The data are summarized in table.

As can be seen from the table, samples of microwave transistors, manufactured by the proposed method (examples 1-3, 5-7, 9-11), have a power output of about 150, 850 and 1290 mW, respectively, a gain of about 5.5, to 8.7 and 9.5 dB, respectively, in contrast to samples of the prototype (examples 4, 8, 12), which have a power output of 100, 730 and 1123 mW, respectively, the gain of the order of about a 3.0, and 8.0 and 8.5 dB.

While maintaining long-term stability of these output parameters of the microwave.

Thus, the proposed method of manufacturing of the power transistors microwave will allow for a comparison with the prototype to increase:

output power and gain about 50 percent in the case of used what I substrate of gallium arsenide and 12-15 percent heterostructures based on it.

While maintaining long-term stability of these output parameters of the microwave.

Sources of information

1. RF patent №2012092 IPC H01L 21/318, priority 04.03.1992 published 30.04.1994.

2. RF patent №2216818 IPC H01L 21/3065, priority 28.01.2003 published 20.11.2003.

3. RF patent №2285976 IPC H01L 21/335, priority 06.05.2005 published 20.10.2006 - prototype.

Table
№ p/pTechnological parametersMeasurements
Structure typeThe thickness of the protective dialect.
layer (μm)
Protective pestiviruses layersModes of HRP applicationVoltage. breakdown (B)Leakage current at Uc=16B (mA)Exit
capacity (watts)
Ratios
UNT gain (DB)
Dolgov. stability at 100°C environment (h)
Si3N4(µm)SiO2(µm)so-RA (°C)Time (s)
10,20,04750,047532520032,51511505,5750
2GaAs0,150,0450,045300150301511505,5750
30,250,050,0535025035151140of 5.4750
4proto
type
0,2oduct
exists
oduct
exists
oduct
exists
oduct
exists
oduct
exists
121100~3750
50,20,04750,047532520032,525≤1,58458,7750
6rnent0,150,0450,0453001503025≤1,58508,7750
70,250,050,05350 2503525≤1,58508,7750
8proto
type
0,2oduct
exists
oduct
exists
oduct
exists
oduct
exists
oduct
exists
20≤57307,8750
90,20,04750,047532520032,535<112909,5750
10DpHEMT0,150,0450,045300150303512999,5750
110,250,050,053502503535<112819,4750
12proto
type
0,2oduct
exists
oduct
exists
oduct
exists
oduct
exists
oduct
exists
32,5≤611238,5750

1. A method of manufacturing a powerful microwave transistor, comprising forming on the front side of the semiconductor substrate topology, at least one transistor crystal by means of lithography processes, the formation of electrodes of the transistor by means of a sputtering system metals, forming ohmic contacts in the area of the electrodes of the source and drain and the potential the social barrier in the area of the gate electrode, forming at least one protective dielectric layer over the entire topology of the transistor crystal by a plasma chemical deposition, the total thickness of 0.15-0.25 μm, the formation of die size transistor through processes of lithography and chemical etching, wherein prior to forming the crystal size of the transistor in the region of the gate electrode is conducted additionally local plasma etching of the protective dielectric layer to a depth equal to its thickness, and directly next carry out the formation of a protective passivating dielectric layers by means of plasma-chemical deposition of a direct sequence system of dielectric layers of nitride and silicon dioxide thickness equal to each 0,045-0,050 μm, and chemical finishing and the protective dielectric layer is carried out at the same technological modes - when the power of the plasma 300-350 watts, for 30-35 at a temperature of 150-250°C, and when forming die size transistor perform chemical etching protective passivating dielectric layer and the protective dielectric layer and in a single technological cycle.

2. A method of manufacturing a powerful microwave transistors according to claim 1, characterized in that a semiconductor substrate using gallium is ally or heterostructures based on it.

3. A method of manufacturing a powerful microwave transistors according to claim 1, characterized in that when forming die size transistor using chemical or plasma etching.

4. A method of manufacturing a powerful microwave transistors according to claim 1, characterized in that the protective pestiviruses dielectric layers applied over the entire topology of the transistor or in the area of the gate electrode.



 

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15 cl, 4 dwg

FIELD: electricity.

SUBSTANCE: method for manufacture of powerful SHF transistor includes application of a solder layer to the flange, shaping of pedestal, application of a sublayer fixing the transistor crystal to the pedestal, formation of p-type conductivity oriented at the plane (111) at the base substrate of single-crystalline silicon and auxiliary epitaxial layers, application of the basic layer and buffer layer for growing of epitaxial structure of a semiconductor device based on wide-gap III-nitrides, application of heat conductive layer of CVD polycrystalline diamond to the basic layer, removal of the basic substrate with auxiliary epitaxial layers up to the basic layer, growing of heteroepitaxial structure based on wide-gap III-nitrides on the basic layer and formation of the source, gate and drain. The heat conductive layer of CVD polycrystalline diamond is used as a pedestal; nickel is implanted to its surficial region and annealed. Before formation of the source, gate and drain an additional layer of insulating polycrystalline diamond and additional layers of hafnium dioxide and aluminium oxide are deposited on top of the transistor crystal; the total thickness of the above layers is 1.0-4.0 nm.

EFFECT: invention allows increased heat removal from the active part of SHF-transistor and minimisation of gate current losses.

6 cl, 4 dwg

FIELD: electronic equipment.

SUBSTANCE: invention is intended to create discrete devices and microwave integrated circuits with the help of field-effect transistors. Method of making field-effect transistor, including creation of drain and source contacts on the contact layer of semiconductor structure and extraction of active region, metal or metal and dielectric mask is applied directly on the surface of contact layer, formation of submicron slot in the mask for further etching operations of contact layer etching and application of T-shaped gate metal through resist mask, after application of the first metal mask lithography for opening windows is carried out when one of the edges coincides with location of Schottky gates in manufactured transistor, and after opening windows the second metal or dielectric mask is applied on the whole surface, remove resist and by lithography create window in resist surrounding slits formed between two metals or between metal and dielectric, perform selective etching of contact layer, after which spray metal films to form T-shaped gates. As a result, edges of T-shaped gate heads on both sides resting on metal or metal and dielectric masks. Then, via selective etching the mask is removed from under the "wings" of T-shaped gate and from the surface of transistor active area. After that, the surface of transistor active area, containing drain, source contacts and Schottky gates, is coated with a passivating layer of dielectric so that under "wings" of T-shaped gate cavities are formed filled with vacuum or gas medium.

EFFECT: technical result is production of gated with length less than 100 nm, as well as reduced thickness of the metal mask and elimination of intermediate layer of dielectric placed between the active region surface and mask.

1 cl, 1 dwg

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