Method for manufacture of nanosensor
SUBSTANCE: invention is related to micro- and nanoelectronics and may be used in production of integral silicon chemical and biosensors for automated control of environment, in ecology, in chemical production, in biology and medicine. Invention is aimed at reduction of nanosensor size, reduction of defectiveness, increased sensitivity, repeatability and efficiency, achievement of compatibility with standard industrial technology VLSI. In method for manufacture of nanosensor, which consists in the fact that dielectric layer is created on silicon substrate, and on surface of dielectric layer silicon layer is formed, from which nanowire with ohm contacts is formed via mask by etching, etching for formation of nanowire with ohm contacts of specified size is carried out in vapours of xenon difluoride with the rate of 36÷100 nm/min, at temperature of 5÷20°C, for 0.3÷1.3 min., silicon layer, from which nanowire is formed with ohm contacts by etching, is created with thickness of 11÷45 nm, and etching mask used is mask of polymer polymethyl methacrylate with thickness of 50÷150 nm.
EFFECT: reduction of nanosensor size, reduction of defectiveness, increased sensitivity, repeatability and efficiency, achievement of compatibility with standard industrial technology VLSI.
The invention relates to micro - and nanoelectronics, nanosensors and can be used in the manufacture of integrated silicon chemical and biosensors for automated control of environment, ecology, chemical industry, biology and medicine.
A known method of manufacturing nanosensor (Z.Li, Y.Chen, X.Li, T.I.Kamins, .Nauka, R.S.Williams, "Sequence-Specific Label-Free DNA Sensors Based on Silicon Nanowires". - NANO LETTERS, Vol.4, No.2, (2004) pp.245-247), namely, that the primary sensing element of nanosensor - silicon nanowires with ohmic contacts on the dielectric layer on a silicon substrate is formed by electron lithography and reactive ion etching, which is detectionrate procedure for silicon, which is formed nanowires.
The disadvantages of the known technical solutions include the following.
First, reactive ion etching of silicon nanowires leads to defect formation in silicon (lateral amorphization of the silicon crystal in the nanowires), which reduces the sensitivity nanosensors and limits the minimum size of the working nanosensors (50 nm width nanowire).
Secondly, get the nanosensors are low sensitivity and high noise, caused, apparently, by the peculiarities of the process of reactive ionov the etching of silicon nanowires, followed in all probability the amorphization of silicon nanowires. The result of this circumstance does not allow to reduce the width of the resulting nanowires to the required values (less than 10÷30 nm).
Third, reactive ion etching of silicon nanowires structures in silicon-on-insulator has a low selectivity with respect to etching of the underlying layer, a buried silicon oxide and leads to the accumulation of movable electric charge in the buried oxide of silicon and increase leakage currents through the buried oxide.
Another known technical solution is the method of manufacturing nanosensor (Eric Stern, James F. Klemic, David A. Routenberg, Pauline N. Wyrembak, Daniel B. Turner-Evans, Andrew D. Hamilton, David A. La Van, Tarek M. Fahmy, Mark A. Reed, Label-free immunodetection with CMOS-compatible semiconducting nanowires. - Nature, Vol.445, No.7127 (2007), pp.519-522), namely, that the primary sensing element of nanosensor - silicon nanowires with ohmic contacts on the dielectric layer on the silicon substrate is formed a liquid chemical etching of silicon hydroxide of Tetramethylammonium through the mask dielectric of silicon dioxide.
The disadvantages of the known technical solutions include the following.
First, due to the nature of this method, probably due to anisotropic liquid etching kristallographie, when the face (111) etched in 100 times slower than the other facets minimum width of silicon nanowires with a trapezoidal cross-section varies from 50 nm to 100 nm (the width of the top face).
Secondly, features of liquid etching of the silicon carbon-containing organic provide the Etchant repeated attacks increased requirements to the defectiveness of the mask and the layer of silicon, and the defectiveness of the buried oxide structures in silicon-on-insulator and does not allow due to capillary effects and hydrodynamics of liquid reproducibly provide the Etchant to reduce the width of the resulting silicon nanowires to the required values (less than 10÷30 nm).
Third, the problematic use of this method in industry standard technology VLSI due to organic carbon provide the Etchant of silicon, low controllability and reproducibility of the etching liquid in the nanometer size range, low compliance with environmental and hygiene standards.
The technical result of the invention is:
- reduced size of nanosensor, respectively, increased sensitivity;
- reducing defects, improving the reproducibility and efficiency;
achieving compatibility with industry standard technology VLSI due to slow gas etching a layer of silicon on metrovoi thickness in vapor diferida xenon.
The technical result is achieved in that in the method of manufacturing nanosensor, namely, that on a silicon substrate to create a dielectric layer on the surface of which is grown a layer of silicon, from which the etching through the mask to form the nanowires with ohmic contacts, and etching to given dimensions nonprobate with ohmic contacts is carried out in vapor diferida xenon.
The silicon layer from which the etching form the nanowires with ohmic contacts, put a method DELICUT in a layer thickness of 11÷45 nm, and the etching vapor diferida xenon spend with a speed of 36÷100 nm/min at a temperature 5÷20°C within 0.3÷1,3 minutes
As the mask for etching using the mask of poly resin thickness of 50÷150 nm.
Gas chemical etching of silicon in vapor diferida xenon has a very high selectivity (>1000, <100000) with respect to the etching of the underlying dielectric layer of silicon dioxide.
For the formation of nanowires with ohmic contacts the silicon layer poison vapor diferida xenon with a speed of 36÷100 nm/min At a speed of etching is less than 36 nm/min is not the etching of the silicon layer, and forming the lower diferido silicon surface passivation layer of silicon. When etching rates greater than 100 nm/min is strong the edge roughness of the nanowires. When the temperature of the etching below 5°C in the surface layer of silicon deposited atmospheric water, which hydrolyzes SiF4, formed HF and degradation of the underlying dielectric layer of silicon dioxide. When the temperature of the etching above 20°C. the etching rate of the silicon is reduced. At the time of etching is less than 0.3 min stay neprotivlenie Islands silicon layer. At the time of etching more than 1.3 min the side of rastra silicon layer and gap nanowires. When using a mask for etching of the polymer polymethylmethacrylate thickness less than 50 nm are observed holes in the mask, which lead to retrevo silicon layer under the mask of poly resin. When the thickness of the mask for etching of more than 150 nm cannot be obtained nanowires necessary width (10÷30 nm).
The invention is illustrated in the following description and the accompanying figures.
Figure 1 shows the image of silicon nanowires with ohmic contacts on the dielectric layer on a silicon substrate obtained in an optical microscope, where 1 is a silicon nanowires, 2 - ohmic contacts, 3 - dielectric layer on a silicon substrate.
Figure 2 shows the image of silicon nanowires obtained in the scanning electron microscope, where 4 - slice of silicon nanowires with a width of ~0 nm.
Figure 3 shows the measured effect of the field on the conductivity of silicon nanowires of nanosensor when using the substrate as the lower bolt, which is characterized by high sensitivity of the nanowires to the external electrical influences, with 5 - volt-ampere characteristic (VAC) of silicon nanowires in dependence of the current on the voltage on the ohmic contacts at different voltage on a silicon substrate (20÷50).
For the implementation of the proposed method of manufacturing nanosensor the silicon layer of nanometer thickness is etched in a thread a couple of diferida xenon:
For this pilot was picked up by the etching vapor diferida xenon with the following relevant modes. As the mask for etching was used, the polymer is polymethylmethacrylate.
The thickness of the silicon layer along with the optical density of the silicon control method of ellipsometric measurements. The depth of etching of the silicon controlled using a scanning electron microscope, which allows to obtain an image of the surface produced offered by way of the nanowires and the depth of the gas etching of the silicon layer. In the proposed method, this value was 11÷45 nm.
The duration of the etching gas of silicon nanowires vapor diferida xenon (XeF 2) is determined by the thickness of the base forming a layer of silicon. In the proposed method, this parameter varies from 0.3 min to 1.3 minutes Completeness etching source forming a layer of silicon controlled by electrical measurements of leakage currents between adjacent nanowires.
As examples of implementation of the proposed method cited the following examples.
As the substrate using a semiconductor wafer of silicon with a thickness of 350 μm with grown on her thermal oxide of silicon with a thickness of 300 nm. As a semiconductor, which is the source material forming the layer using the silicon caused by the method DELICUT in a layer thickness of 11 nm. For the formation of nanowires with ohmic contacts, the source forming the silicon layer poison vapor diferida xenon with a speed of 36 nm/min at a temperature of 5°C, within 0.3 min through a mask made of poly resin with a thickness of 50 nm.
By nanowires of silicon of a thickness of 11 nm and a width of 30 nm. Created nanowires proposed method have smaller dimensions in comparison with the known technical solutions (see figure 2), the minimum width of the nanowires is ~30 nm.
As the substrate using a semiconductor wafer of silicon with a thickness of 350 μm with grown it t is recheckin oxide of silicon with a thickness of 300 nm. As a semiconductor, which is the source material forming the layer using the silicon caused by the method DELICUT in a layer thickness of 25 nm. For the formation of nanowires with ohmic contacts, the source forming the silicon layer poison vapor diferida xenon at a speed of 60 nm/min at the temperature of 15°C for 0.7 min through a mask made of poly resin with a thickness of 100 nm.
By nanowires of silicon of a thickness of 25 nm and a width of 30 nm. Created nanowires proposed method have smaller dimensions in comparison with the known technical solutions (see figure 2), the minimum width of the nanowires is ~30 nm.
As the substrate using a semiconductor wafer of silicon with a thickness of 350 μm with grown on her thermal oxide of silicon with a thickness of 300 nm. As a semiconductor, which is the source material forming the layer using the silicon caused by the method DELICUT in a layer thickness of 45 nm. For the formation of nanowires with ohmic contacts, the source forming the silicon layer poison vapor diferida xenon at a rate of 100 nm/min, at a temperature of 20°C, for min 1,3 through the mask of poly resin with a thickness of 150 nm.
By nanowires of silicon of a thickness of 45 nm and a width of 30 nm. Created nanowires pre the proposed method have smaller dimensions in comparison with the known technical solutions (see 2), the minimum width of the nanowires is ~30 nm.
Thus, the proposed method of manufacturing nanosensor allows to reduce the dimensions of the nanowires, as well as to improve electrical properties generated by this method nanowires: to reduce the leakage currents through the lower dielectric layer, to increase the manageability of nanosensor by expanding the range of voltages from the bottom of the shutter and to increase sensitivity nanosensors due to the greater conductivity at a lower concentration of charge carriers.
On the other hand, the positive effect of this invention is to microminiaturization nanosensors on SOI (silicon-on-insulator), which leads to improved reliability, performance, sensitivity, and the degree of integration while reducing their costs and improving environmental performance of the production process, compliance with sanitary and hygiene standards, as well as achieving full compatibility with industrial silicon VLSI technology.
The method of manufacturing nanosensor, namely, that on a silicon substrate to create a dielectric layer on the surface of which is formed a silicon layer, which through a mask by etching to form the nanowires with ohmic contacts, wherein the etching for the formation of nanowires with ohmic the contacts of a given size is carried out in vapor diferida xenon with a speed of 36÷100 nm/min, when the temperature 5÷20°C, within 0.3÷1,3 min, the silicon layer from which the etching form the nanowires with ohmic contacts, create thickness 11÷45 nm, and as a mask for etching using the mask of poly resin thickness of 50÷150 nm.
SUBSTANCE: invention concerns technological process of microsystems manufacturing. The method of outer corner over-etching compensation in solid figures etched on silicon plates with surface orientation by anisotropic chemical etching involves formation of protection layer on both surfaces of the silicon plate, formation of symmetrically superimposed topological masks of an etch figure with compensation elements on both sides of the silicon plate. Compensation plates take form of bridges transforming topological pattern of an etch figure with outer corners into a topological pattern with only inner corners. Then the plate undergoes anisotropic through etching from both sides simultaneously, so that the compensation elements are removed in the process of the silicon plate etching.
EFFECT: improver precision and repeatability of configuration and size of etched solids.
FIELD: electronic engineering.
SUBSTANCE: in photolithography method first the surface of single protective layer is coated with the first layer of photoresist, where the first hardened photoresist relief is formed, in such a way so that one part of this relief borders coincides with corresponding part of required profile borders that is subject to etching in protective layer. At that dimensions of the first relief are at least two times more than the dimensions of required profile. After that the second layer of photoresist is applied above the first relief, where the second hardened photoresist relief is created in such a way so that part of this second relief borders coincides with remaining part of required profile borders. At that second relief dimensions are at least two times more than dimensions of required profile. In that way the resulting hardened relief is received, the borders of which are precisely corresponding to the borders of required profile. After that etching of protective layer is carried out in single etchant of corresponding composition through the window in shaped photoresist mask, and the required profile is obtained.
EFFECT: reduces material and labour expenditures necessary for receiving relief elements with dimensions of not more than 1 micrometer.
FIELD: microelectronics; manufacture of micromechanical devices, crystal resonators, and the like.
SUBSTANCE: proposed method for producing embossed surface on dielectric and piezoelectric substrates incorporating silicon dioxide in their composition includes application of shielding mask in the form of multilayer thin-film system of two materials onto its surface and formation of shielding mask configuration, substrate etching, and removal of shielding mask; used as shielding mask is multilayer thin-film system of yttrium- yttrium oxide obtained by evaporation in vacuum, yttrium layer thickness being minimum 1 μm and yttrium oxide thickness, minimum 0.05 μm. Intermediate layer of mixture of these materials can be formed between yttrium layer and yttrium-oxide layer.
EFFECT: enhanced yield due to eliminating voids and interruptions in shielding layer, reduced cost of end product.
FIELD: semiconductor silicon device manufacture.
SUBSTANCE: proposed method for manufacturing semiconductor devices on crystal-oriented (100) silicon wafers involves organization of regions with semiconductor device layout components on one of silicon wafer sides and wafer division into chips, as well as wafer thinning by chemical etching in etchant selective for crystal orientation (100); in the course of manufacture shielding mask is formed prior to etching on underside of wafer to shield peripheral regions of wafer so that internal configuration of mask area periphery coincides with outer one of structures on face side of wafer.
EFFECT: enhanced yield.
FIELD: producing sensing mass hanger flexible members for micromechanical measuring devices.
SUBSTANCE: proposed method for manufacturing flexible member of micromechanical device includes oxidation of single-crystalline silicon plate with its surface positioned in plane 100, covering of this plate on both ends with photoresist layer, windows being opened in photoresist layer in advance by means of double-ended photolithography, oxidant etching on opened windows of width L1 in vicinity of flexible member formation, and anisotropic etching of plate to intermediate depth h. After oxidant etching groove of width L1 and length M is made at point of flexible member formation by way of anisotropic etching up to self-stopping, windows are opened again in oxidant for final formation of flexible member, and anisotropic etching is conducted to obtain desired thickness of flexible member H whose thickness is to be found from formula H = (T1 - Tgr)V, where T1 is etching time for projecting corners of groove; Tgr is groove formation time; V is anisotropic etching rate,
EFFECT: reduced labor consumption, enhanced precision and quality.
1 cl, 5 dwg
FIELD: physics, semiconductors.
SUBSTANCE: invention is related to methods for creation of metal nanowires on surface of semiconductor substrates and may be used in creation of solid-state electronic instruments. Substance of invention: in method for creation of conducting nanowires on surface of semiconductor substrates, copper is deposited on surface of silicon Si(lll) with formation of buffer layer of copper silicide Cu2Si at the temperature of 500°C under conditions of ultrahigh vacuum. Buffer layer of copper silicide is formed with monatomic thickness, afterwards at temperature of 20°C at least 10 layers of copper are deposited on atomic steps of buffer layer surface, which form nanowires of epitaxial copper that are oriented along atomic steps of substrate.
EFFECT: provides for creation of nanowires that possess high conductivity, with the possibility of these nanowires formation location control.
SUBSTANCE: method includes heating of silica oxide photon crystals with modifying agent - crystal phosphor cesium iodide in vacuum at temperature not less than 800°C during not less than 15 hr. Cesium iodide can be activated with different admixtures (Na, Tl, In, CO3 etc), providing more bright (in comparison with pure CsJ) radioluminescence on the different waves of the visible-light spectrum. Usage of the scintillator - cesium iodide as filler provides good wettability (caused by capillary forces) of silica oxide microspheres with the melted cesium iodide without outer pressure. It allows to obtain optically inverted composite having approximately the same optical contrast (ratio of the refractive indexes relating to microspheres medium and to the medium filling the pores between microspheres) as initial silica oxide has.
EFFECT: obtaining of the end product with high yield.
4 cl, 1 ex, 2 dwg
FIELD: production processes.
SUBSTANCE: in compliance with the proposed method, copper matrix is pressed at 100 to 300 MPa and sintered at 5640 to 680°C for 1 to 2 h in protective-reducing gaseous atmosphere to produce apparent-porosity structure. Nonstructural component is introduced therein in vacuum impregnation of the matrix with suspension of refractory material nanoparticles in glycerin-based protective fluid at 1 to 10 kPa. Aforesaid protective fluid is removed at 80 to 95% of its boiling point. Finally, final sintering is effected at 810 to 1020°C for 1 to 2 h in protective-reducing gaseous atmosphere.
EFFECT: simplified process, expanded technological performances, improved physical-mechanical properties.
3 cl, 1 tbl, 1 ex
SUBSTANCE: prealloyed powder is received by means of mechanical activation of powders mixture of initial components at temperature, not exceeding 150°C, up to formation in powder of nanostructural and/or amorphous state. Directly after the activation it is implemented pressing at pthe pressure not less than 510 MPa at oom temperature or 0.2 Tmelt or, where Tmelt - melting temperature of the lowest melt component of powder composition, or at crystallisation temperature of amorphous phase.
EFFECT: increasing of density, strength with keeping of peculiarities of structural condition, received at mechano-chemical synthesis.
1 tbl, 2 ex
SUBSTANCE: proposed laser material is a ceramic polycrystalline microstructure substance with particle size of 3-100 mcm, containing a twinned nanostructure inside the particles with size of 50-300 nm, made from halides of alkali, alkali-earth and rare-earth metals or their solid solutions, with vacancy or impurity laser-active centres with concentration of 1015-1021 cm-3. The method involves thermomechanical processing a monocrystal, made from halides of metals, and cooling. Thermomechanical processing is done until attaining 55-90% degree of deformation of the monocrystal at flow temperature of the chosen monocrystal, obtaining a ceramic polycrystalline microstructure substance, characterised by particle size of 3-100 mcm and containing a twinned nanostructure inside the particles with size of 50-300 nm.
EFFECT: improved mechanical properties, increased microhardness and failure viscosity.
5 cl, 1 tbl, 4 ex, 1 dwg
SUBSTANCE: method involves chemical reduction of noble metal ions from an aqueous solution of its compound with a reducing agent being anionic polyelectrolyte and noble metal ions concentrated 0.1-5 mg-ion/dm3 and polyelectrolyte concentrated 5-350 mg/dm3. The process is intensified due to temperature rise within 20-60°C and/or light exposure 500-3000 lux.
EFFECT: invention allows for nano- and micro- monocrystals in free liquid volume without sol particle impurity while maintaining the size within specified range.
9 cl, 12 ex, 1 tbl, 5 dwg
FIELD: technological processes.
SUBSTANCE: during manufacture of structured surface wood grain pattern is applied on board surface (2) by means of printing method, then the first partially optically transparent coating (22) from varnish is applied on wood grain pattern. Using method of direct or indirect printing, the first coating is coated with partially optically transparent second coating (24) from varnish with spatially varied distribution of applied substance amount so that the second layer creates negative surface structure, in which surface structures that actually imitate indents are created in the form of elevations (28).
EFFECT: provides for improvement of surface structure.
39 cl, 11 dwg
SUBSTANCE: present invention can be used in pharmaceutical, food, chemical and electronic industry when making catalysts, polymers, pesticides and coatings. An aqueous solution of micronised substance is poured from container 6 into a high pressure cell 5. Using a high pressure pump 2, carbon dioxide is fed from cylinder 1 into booster cylinder 4 and cell 5 until attaining pressure in the range of 90-400 atm. Temperature in booster cylinder 4 and cell 5 is kept in the range of 33 - 160°C. The obtained two-phase system (aqueous solution of substance/carbon dioxide) is dispersed through a spray nozzle 10 at 100-200°C temperature. Supercritical carbon dioxide acts as the "plunger". Nano- and micro-sized particles formed in the dispersion chamber are trapped in separator 8.
EFFECT: invention allows for obtaining aerosols and powders of water soluble substances of nano- and micro-sizes without using harmful organic solvents.
3 cl, 4 dwg, 6 ex
FIELD: physics, optics.
SUBSTANCE: invention is related to the field of nuclear power microscopes and probes used in mentioned microscopes. Probe for application in nuclear power microscope or for nanolithography comprises force-measuring element connected to probe tip with tip radius of 100 nm or less. Force-measuring element has low coefficient of merit for at least one mode of force-measuring element oscillations, at that specified probe is arranged so that in case of action of force applied at probe from the outside, displacement force presses probe tip or sample, or both to each other with value that exceeds restoration force occurring as a result of probe tip shift in process of sample probing. Coefficient of merit may be reduced by plate coating with material that scatters mechanical energy.
EFFECT: improvement of sample surface tracing with probe, accelerated provision of scanned images.
30 cl, 12 dwg
FIELD: physics, marking.
SUBSTANCE: invention is related to methods for precious items counterfeit protection and may be used for valuables counterfeit protection. At that on precious item passive protective facility is formed with specified structure with application of semiconductor nanostructure with quantum wells, detected informative criterion used is circular photovoltaic effect. Detection is realised by means of analysis of electric response of protective facility at external probing action of electromagnet radiation with further visual and automatic comparison of registered parameters of informative criteria with informative criteria.
EFFECT: increased reliability of counterfeit protection and duplication of valuables.
4 cl, 3 dwg
FIELD: carbon materials.
SUBSTANCE: weighed quantity of diamonds with average particle size 4 nm are placed into press mold and compacted into tablet. Tablet is then placed into vacuum chamber as target. The latter is evacuated and after introduction of cushion gas, target is cooled to -100оС and kept until its mass increases by a factor of 2-4. Direct voltage is then applied to electrodes of vacuum chamber and target is exposed to pulse laser emission with power providing heating of particles not higher than 900оС. Atomized target material form microfibers between electrodes. In order to reduce fragility of microfibers, vapors of nonionic-type polymer, e.g. polyvinyl alcohol, polyvinylbutyral or polyacrylamide, are added into chamber to pressure 10-2 to 10-4 gauge atm immediately after laser irradiation. Resulting microfibers have diamond structure and content of non-diamond phase therein does not exceed 6.22%.
EFFECT: increased proportion of diamond structure in product and increased its storage stability.