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Showing papers on "Silicon nitride published in 1991"


Journal ArticleDOI
TL;DR: In this paper, the authors review the achievements to date in understanding and modeling diverse stress problems in silicon integrated circuits, including CVD (chemical vapor deposition) silicon nitride, silicon dioxide, polycrystalline silicon, etc.
Abstract: The silicon integrated‐circuits chip is built by contiguously embedding, butting, and overlaying structural elements of a large variety of materials of different elastic and thermal properties. Stress develops in the thermal cycling of the chip. Furthermore, many structural elements such as CVD (chemical vapor deposition) silicon nitride, silicon dioxide, polycrystalline silicon, etc., by virtue of their formation processes, exhibit intrinsic stresses. Large localized stresses are induced in the silicon substrate near the edges and corners of such structural elements. Oxidation of nonplanar silicon surfaces produces another kind of stress that can be very damaging, especially at low oxidation temperatures. Mismatch of atomic sizes between dopants and the silicon, and heteroepitaxy produce another class of strain that can lead to the formation of misfit dislocations. Here we review the achievements to date in understanding and modeling these diverse stress problems.

479 citations


Journal ArticleDOI
TL;DR: In this paper, the valence band density of electron states shows a lone pair band and a deeper bonding band as usual, impurities have a greater effect in the nitride than in conventional lone pair semiconductors.
Abstract: Silicon Nitride is found to have a valence band maximum of nitrogen lone pair p electrons because of the planar nitrogen site. This contrasts with the usual lone pair semiconductors, such as SiO2, caused by a p4 valence configuration. Consequently although the valence band density of electron states shows a lone pair band and a deeper bonding band as usual, impurities have a greater effect in the nitride than in conventional lone pair semiconductors. Hole transport is also discussed.

246 citations


Journal ArticleDOI
TL;DR: In this paper, a variant of the scanning capacitance microscope (SCaM) is described, which is based on the atomic force microscope and involves a cantilever beam that is used to press a conducting tip against a conducting substrate coated with a dielectric film.
Abstract: In this paper we describe a variant of the scanning capacitance microscope (SCaM) which is based on the atomic force microscope. Our SCaM involves a cantilever beam that is used to press a conducting tip against a conducting substrate coated with a dielectric film. A capacitance sensor is then used to measure the tip‐sample capacitance as a function of lateral position. The deflection of the cantilever can also be used to measure independently the surface topography. This microscope can be used to measure electrical properties of dielectric films and their underlying substrates. We have applied this microscope to the study of the nitride‐oxide‐silicon (NOS) system. This system has been studied extensively because of its ability to store information by trapping charge in the silicon nitride. Commercial semiconductor nonvolatile memories have been designed using this NOS technology. We have used the SCaM tip to apply a localized bias to the NOS sample, causing charge to tunnel through the oxide layer and to...

235 citations


Journal ArticleDOI
TL;DR: In this paper, a silicon nitride (SiN) film was prepared using silane and nitrogen source gases with helium dilution, and the film properties, including N/Si ratio, hydrogen content and electrical quality are most sensitive to changes in the silane flow rate during deposition.
Abstract: We have deposited silicon nitride films by plasma‐enhanced chemical vapor deposition (PECVD) at 250 °C with properties similar to films prepared at 700 °C by low‐pressure chemical vapor deposition (LPCVD). Films are prepared using silane and nitrogen source gases with helium dilution. The film properties, including N/Si ratio, hydrogen content and electrical quality are most sensitive to changes in the silane flow rate during deposition. For films deposited under optimized conditions at a substrate temperature of 250 °C, current versus voltage measurements in metal‐insulator‐semiconductor structures show the onset of carrier injection at 3–4 MV/cm, slightly lower than LPCVD films. When bias‐stressed to 2 MV/cm, capacitance versus voltage measurements show some hysteretic behavior and evidence for positive fixed charge, similar to LPCVD films. For the optimized films: N/Si=1.33±.02; refractive index (λ=6328 A)=1.980±0.01; dielectric constant (1 MHz) ∼7.5; density=2.7±0.1; and the etch rate in 10% buffered ...

199 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide new perspectives on why the oxidation rates of silicon carbide and silicon nitride are lower than those of silicon and on the conditions under which gas bubbles can form on them.
Abstract: This study provides new perspectives on why the oxidation rates of silicon carbide and silicon nitride are lower than those of silicon and on the conditions under which gas bubbles can form on them The effects on oxidation of various rate-limiting steps are evaluated by considering the partial pressure gradients of various species, such as O2, CO, and N2 Also calculated are the parabolic rate constants for the situations when the rates are controlled by oxygen and/or carbon monoxide (or nitrogen) diffusion These considerations indicate that the oxidation of silicon carbide and silicon nitride should be mixed controlled, influenced both by an interface reaction and diffusion

180 citations


Patent
Hiroshi Yamamoto1
15 Oct 1991
TL;DR: The underlying and overlying silicon nitride layers have different degrees of hydrogen content as discussed by the authors, and the overlying layer has more than or equal to twice the hydrogen content of the underlying layer.
Abstract: A semiconductor device is protected by a passivation layer, which includes underlying and overlying silicon nitride layers deposited by the plasma-assisted CVD method by changing layer forming conditions. The silicon nitride layers respectively have their intrinsic compressive stresses. The underlying silicon nitride layer in contact with a metal wiring layer has the intrinsic compressive stress of 3×10 9 to 1×10 10 dyne/cm 2 . The overlying silicon nitride layer has the intrinsic compressive stress which is less than or equal to half of the intrinsic compressive stress of the underlying silicon nitride layer. The underlying and overlying silicon nitride layers have different degrees of the hydrogen content. The underlying silicon nitride layer has the hydrogen content of 0.5×10 20 to 5×10 21 atm/cm 3 . The overlying silicon nitride layer has the hydrogen content which is more than or equal to twice of the hydrogen content of the underlying silicon nitride layer.

179 citations


Journal ArticleDOI
TL;DR: In this paper, MeV erbium ion implantation into micron-thick silica and phosphosilicate glass films and 1200-Athick Si3N4 films was studied with the aim of incorporating the rare earth dopant on an optically active site in the network.
Abstract: Implantation of MeV erbium ions into micron‐thick silica and phosphosilicate glass films and 1200‐A‐thick Si3N4 films is studied with the aim of incorporating the rare‐earth dopant on an optically active site in the network. Implantation energies and fluences range from 500 keV to 3.5 MeV and 3.8×1015 to 9.0×1016 ions/cm2. After proper thermal annealing, all implanted films show an intense and sharply peaked photoluminescence spectrum centered around λ = 1.54 μm. The fluorescence lifetime ranges from 6 to 15 ms for the silica‐based glasses, depending on annealing treatment and Er concentration. Silicon nitride films show lower lifetimes, in the range <0.2–7 ms. Annealing characteristics of all materials are interpreted in terms of annealing of ion‐induced network defects. These defects are identified using photoluminescence spectroscopy at 4.2 K. Concentration quenching, diffusion and precipitation behavior of Er is also studied.

177 citations


Journal ArticleDOI
TL;DR: In this paper, an absolute pressure transducers with four diaphragms, two active and two inactive, have been constructed and optimized towards manufacturability, and the measured performance is excellent and agrees with the predictions of the design algorithm.
Abstract: Typical IC processing is fundamentally two dimensional; sensors are three-dimensional structures. In surface micromachining, two-dimensional IC processing is extended to sensor structures by the addition of one or more sacrificial layers which are removed by lateral etching. The resulting sensor structures involve the substrate and one or more deposited films which form the intended micromechanical component. The concepts of this type of sensor manufacturing are readily demonstrated by considering absolute pressure transducers in some detail. Absolute pressure transducers involve a vacuum-sealed cavity and a deformation sensing technique. The cavity is formed from the substrate and a low-pressure chemical vapor deposited polycrystalline silicon film. The mechanical properties of this film must be controlled well enough to allow the device to be designed. This implies morphological control during processing. Optimized films which do exhibit controlled compressive or tensile strains exclude oxygen or nitrogen and are therefore not modified by extended hydrofluoric acid etches. Their mechanical behavior is monitored by micromechanical test structures which measure Euler buckling and thereby determine the value of the built-in strain. The cavity vacuum is established by reactive sealing. Long-term vacuum integrity is achieved by a low-stress silicon nitride barrier which also acts as a dielectric isolation barrier. Sensing is accomplished via deposited polysilicon resistors. These devices behave like metal resistors in terms of their temperature coefficient of resistance and noise figure. Their piezoresistive behavior is larger than that of typical metal film structures and smaller than that of single-crystal resistors. Pressure sensors with four diaphragms, two active and two inactive, have been constructed and optimized towards manufacturability. The measured performance is excellent and agrees with the predictions of the design algorithm.

166 citations


Journal ArticleDOI
TL;DR: Deville et al. as discussed by the authors presented an overview of the properties required for Si3N4 powders suitable for advanced ceramics, as well as the manufacturing processes and material properties.
Abstract: Silicon nitride is a ceramic material of great interest to advanced engine construction and mechanical engineering owing to an outstanding combination of favorable properties like high mechanical strength at high temperatures, corrosion and wear resistance, great hardness, and low density. The material is based on high-quality Si3N4 powders, which are shaped and sintered to the ceramic component. This overview outlines the properties required for Si3N4 powders suitable for advanced ceramics. Processes in commerical use and those under development for the production of high quality Si3N4 powders are discussed as well as material manufacturing processes and material properties. By steadily improving powder quality, material properties, and the economy of powder and component production, chemistry and chemical technology play a major role in recent efforts to create a solid fundament for broad applications of silicon nitride ceramics. “If one would surrender to geological phantasies, one could imagine that during the formation of our planet, when elements combined to the compounds making up its crust and mountain ranges, silicon reacted with nitrogen, and the still red-hot nitrogen-silicon, on contact with water, may have decomposed to silicic acid and ammonia. Thus, ammonia may have been formed originally and nitrogen thereby introduced into the forming organic compounds when living nature first started to appear.” H. Sainte-Claire Deville and F. Wohler

140 citations


Journal ArticleDOI
TL;DR: A study of integrated optic devices based on adiabatic principles is reported in this article, which includes a 3-dB coupler, a full coupler and an asymmetric Y-coupler for a 13-155- mu m-wavelength multiplexer.
Abstract: A study of integrated optic devices based on adiabatic principles is reported The components are a 3-dB coupler, a full coupler, a polarization splitter, a wavelength multiplexer, and two mode shape transformers All components were fabricated from doped silica and silicon nitride films on silicon substrates Results are given for an adiabatic full coupler and an adiabatic 3-dB coupler, an asymmetric Y-coupler for a 13-155- mu m-wavelength multiplexer, and a tapered waveguide for mode shape transformation >

135 citations


Journal ArticleDOI
TL;DR: In this paper, the mechanical and electrical properties of nanocomposite materials composed of a Si3N4 matrix and nanometer-sized SiC particles are described and compared.
Abstract: Mechanical and electrical properties of nanocomposite materials composed of a Si3N4 matrix and nanometer-sized SiC particles are described. Composites containing less than 10 vol% SiC particles have the same order of resistivity and dielectricity as the non-SiC material as well as highly improved mechanical properties. The composites are promising materials for use under harsh conditions.

Journal ArticleDOI
TL;DR: In this article, a dependence of Young's modulus of elasticity on open porosity in ceramics is derived from an open-porosity model, which in the literature, is applied to salinity conductivity and fluid permeability in rocks.
Abstract: A dependence of Young's modulus of elasticity on open porosity in ceramics is derived from an open-porosity model, which in the literature, is applied to salinity conductivity and fluid permeability in rocks. A random distribution of grain and pore size is assumed. The relation developed,E(p)=E o(1−"p)m, whereE is the modulus of elasticity of the porous ceramic,E o is the theoretical elastic modulus,p is the porosity andm is an exponent dependent on the tortuosity of the structure of the ceramic, adequately describes the dependence of the modulus of elasticity on porosity. The model is applied to the experimental data from several ceramics such as alumina, silicon nitride, silicon carbide, uranium oxide, rare-earth oxides, and YBa2Cu3O7−δ superconductor, and the value ofm is obtained for each case. We have shown thatm has a value of nearly 2 for sintered ceramics, unless sintering aids or hot pressing have been used during fabrication of the ceramic. Such additional procedures approximately double the magnitude ofm.

Journal ArticleDOI
TL;DR: In this paper, the elastic strain in Al•0.5% Cu metal lines under silicon nitride passivation has been determined by x-ray diffraction, and the experimental stress tensor calculated from these strain values is in excellent agreement with the results of a finite element model calculation.
Abstract: The elastic strain in Al‐0.5% Cu metal lines under silicon nitride passivation has been determined by x‐ray diffraction. The experimental stress tensor calculated from these strain values is in excellent agreement with the results of a finite element model calculation. The intrinsic stress in the dielectric plays no role in influencing the stress in the metal; only thermal stress effects are important.

Patent
16 Oct 1991
TL;DR: In this paper, the authors proposed a process for etching of silicon oxide/nitride such as silicon dioxide, silicon nitride or oxynitride, which can achieve 350% overetching while preventing sputtering of the electrically conductive layer which can be Al, Al alloys, Ti, TiN, TiW and Mo.
Abstract: A process for etching of silicon oxide/nitride such as silicon dioxide, silicon nitride or oxynitride. The process includes etching a silicon oxide/nitride layer to expose an underlying electrically conductive layer and provide a via extending through the silicon oxide/nitride layer to the electrically conductive layer. The etching is performed by exposing the silicon oxide/nitride layer to an etching gas in an ionized state in a reaction chamber of a plasma generating device. The etching gas includes a fluoride-containing gas and a passivating gas which is present in an amount effective to suppress sputtering of the electrically conductive layer when it is exposed to the etching gas during the etching step. The passivating gas can be nitrogen gas and the fluoride-containing gas can be CF 4 , CHF 3 , C 2 F 6 , CH 2 F 2 , SF 6 , other Freons and mixtures thereof. The etching gas can also include a carrier gas such as Ar, He, Ne, Kr or mixtures thereof. The etching can be reactive ion etching or plasma etching and the etching gas can be exposed to a microwave electric field and/or a magnetic field during the etching step. The etching gas can achieve 350% overetching while preventing sputtering of the electrically conductive layer which can be Al, Al alloys, Ti, TiN, TiW and Mo.

Journal ArticleDOI
TL;DR: In this article, a study of the creep and creep rupture behavior of hot-pressed silicon nitride reinforced with 30 vol% SiC whiskers was presented. But, the authors did not consider the effect of whisker additions on the creep rate.
Abstract: This paper presents a study of the creep and creep rupture behaviour of hot-pressed silicon nitride reinforced with 30 vol% SiC whiskers. The material was tested in both tension and compression at temperatures ranging from 1100 to 1250°C for periods as long as 1000 h. A comparison was made between the creep behaviour of whisker-reinforced and whisker-free silicon nitride. Principal findings were: (i) transient creep due to devitrification of the intergranular phase dominates high-temperature creep behaviour; (ii) at high temperatures and stresses, cavitation at the whisker-silicon nitride interface enhances the creep rate and reduces the lifetime of the silicon nitride composite; (iii) resistance to creep deformation is greater in compression than in tension; (iv) the time to rupture is a power function of the creep rate, so that the temperature and stress dependence of the failure time is determined solely by the temperature and stress dependence of the creep rate; (v) as a consequence of differences in grain morphology and glass composition between whisker-free and whisker-reinforced material, little effect of whisker additions on the creep rate was observed.

Journal ArticleDOI
TL;DR: In this article, a set of films with N/Si ratios of 1.0 to 1.5 were produced and the intrinsic compressive stress was found to increase with increasing amounts of N-H bonding.
Abstract: Plasma enhanced chemical vapor deposited silicon nitride thin films, possessing a wide range of mechanical and physical properties, were made by changing the flow rate ratios of the various processing gases, NH3/SiH4/N2, while basically keeping the other deposition parameters constant. A set of films with N/Si ratios of 1.0 to 1.5 were produced, all showing compressive stress. The intrinsic compressive stress was found to increase with increasing amounts of N–H bonding. The density and Young’s modulus also increased with increasing amounts of N–H bonding. The values for Young’s modulus, obtained by using a Nano indenter instrument, were mainly dependent upon the film density, and the hardness to modulus ratio was 0.09 for all of the silicon nitride thin films.

Journal ArticleDOI
TL;DR: In this paper, a surface modification technique using controlled hydrolysis and polymerization of Al-alkoxide is presented to give SiC and Si3N4 powders alumina-like surface properties.
Abstract: A surface modification technique using controlled hydrolysis and polymerization of Al-alkoxide is presented. It was found by measuring the electrokinetic behaviour and the adsorption properties that a minimum amount of about 0·5 mg Al/m2 was necessary to give SiC and Si3N4 powders alumina-like surface properties. This permanent surface coating improved the dispersability of Si3N4 in cyclohexane using a commercial dispersant with an acidic head-group.

Patent
30 Aug 1991
TL;DR: In this article, a method for forming isolated regions of oxide of an integrated circuit, and a circuit formed according to the same, is described, where a pad oxide layer is formed over a portion of a substrate and a polysilicon buffer layer is then formed over the first silicon oxide layer.
Abstract: A method is provided for forming isolated regions of oxide of an integrated circuit, and an integrated circuit formed according to the same. A pad oxide layer is formed over a portion of a substrate. A first silicon nitride layer is formed over the pad oxide layer. A polysilicon buffer layer is then formed over the first silicon nitride layer. A second silicon nitride layer is formed over the polysilicon layer. A photoresist layer is formed and patterned over the second silicon nitride layer. An opening is etched through the second silicon nitride layer and the polysilicon buffer layer to expose a portion of the first silicon nitride layer. A third silicon nitride region is then formed on at least the polysilicon buffer layer exposed in the opening. The first silicon nitride layer is etched in the opening. A field oxide region is then formed in the opening.

Patent
03 Jul 1991
TL;DR: In this article, a low-stress process for creating field isolation regions on a silicon substrate that are fully recessed with respect to active areas is proposed, which has no bird's beak transition regions at their edges.
Abstract: A low-stress process for creating field isolation regions on a silicon substrate that are fully recessed with respect to active areas. The field isolation regions, which have no bird's beak transition regions at their edges, are created by oxidizing an epitaxially-grown layer of silicon, the edges of which are isolated from active area silicon by a an oxide-backed silicon nitride spacer. Each nitride spacer is contiguous with a horizontal silicon nitride layer segment that protects an active area from oxidation during thermal field oxidation. A modification of the process, which requires the deposition of an additional silicon dioxide layer and a wet etch to remove spacers created from that additional layer, further reduces stress during thermal oxidation of the epitaxially-grown silicon layer by providing a void around the periphery of the epitaxial layer for expansion during the thermal oxidation thereof.

Proceedings ArticleDOI
30 Jan 1991
TL;DR: In this article, an electrostatic micromechanical membrane pump for fluids and gases has been designed and fabricated with a process that is compatible with integrated circuits, and the process consists of six photolithography steps and eight low-pressure chemical vapor depositions.
Abstract: An electrostatic micromechanical membrane pump for fluids and gases has been designed and fabricated with a process that is compatible with integrated circuits. The process consists of six photolithography steps and eight low-pressure chemical vapor depositions. No bulk silicon etchants or wafer bonding techniques are used. Each pump consists of an input valve, a pumping membrane, and an output valve. All parts are encapsulated by silicon nitride and are actuated by electrostatic forces. Actuation voltages of approximately 50 V are required for observable valve closure and membrane deflections. Typical gas pumping displacements are between 12 to 640 nL per cycle. >

Patent
16 Aug 1991
TL;DR: In this paper, a high temperature silicon nitride resist is used for microlithographic patterning of a silicon substrate to provide a uniform distribution of diamond nucleation sites and to improve diamond film adhesion to the substrate.
Abstract: A high temperature resist process is combined with microlithographic patterning for the production of materials, such as diamond films, that require a high temperature deposition environment. A conventional polymeric resist process may be used to deposit a pattern of high temperature resist material. With the high temperature resist in place and the polymeric resist removed, a high temperature deposition process may proceed without degradation of the resist pattern. After a desired film of material has been deposited, the high temperature resist is removed to leave the film in the pattern defined by the resist. For diamond films, a high temperature silicon nitride resist can be used for microlithographic patterning of a silicon substrate to provide a uniform distribution of diamond nucleation sites and to improve diamond film adhesion to the substrate. A fine-grained nucleation geometry, established at the nucleation sites, is maintained as the diamond film is deposited over the entire substrate after the silicon nitride resist is removed. The process can be extended to form microstructures of fine-grained polycrystalline diamond, such as rotatable microgears and surface relief patterns, that have the desirable characteristics of hardness, wear resistance, thermal conductivity, chemical inertness, anti-reflectance, and a low coefficient of friction.

Journal ArticleDOI
TL;DR: In this paper, the authors reported the observation of both silicon and nitrogen paramagnetic defect centers using X-band and Q-band electron spin resonance microwave excitation frequencies and demonstrated that the g tensor of the K center exhibits very little anisotropy and that the lineshape is broadened primarily by hyperfine interactions of the nitrogens bonded to the silicon atom.
Abstract: We report the observation of both silicon and nitrogen paramagnetic defect centers using X‐band and Q‐band electron spin resonance microwave excitation frequencies. By using two different microwave frequencies along with a computer analysis of the resonance lineshapes, we have been able to confirm and extend earlier observations regarding the chemical identity of these paramagnetic defects. Specifically, we provide additional evidence that the silicon dangling bond, i.e., K center, is an unpaired electron on a silicon atom bonded to three nitrogen atoms in stoichiometric silicon nitride. We further demonstrate that the g tensor of the K center exhibits very little anisotropy and that the lineshape is broadened primarily by hyperfine interactions of the nitrogens bonded to the silicon atom. We also confirm that the recently observed nitrogen dangling‐bond resonance in silicon nitride is indeed due to a hyperfine interaction with a nitrogen nucleus. This improved understanding of these two important paramagnetic defects may be of importance in eliminating or perhaps exploiting their chemical properties.

Journal ArticleDOI
TL;DR: In this article, the carbon content of the starting mixtures increased the reaction rate by increasing the SiO formation as well as the rate of Si3N4 nucleation, and it is thought that the effect of the carbon particle size on reaction rate is more significant than that of the specific surface area.
Abstract: Silicon nitride powders of high α content were prepared from mixtures of very fine amorphous silica and carbon powders in flowing nitrogen at 1400–1500°C. The higher the reaction temperature within this range the lower the yield of silicon nitride in spite of a higher rate of SiO generation. The overall reaction rate increased with increasing nitrogen flowrate. An increase of carbon content of the starting mixtures increased the reaction rate by increasing the rate of SiO formation as well as the rate of Si3N4 nucleation. It is thought that the effect of the carbon particle size on the reaction rate is more significant than that of the specific surface area. The amount of silicon carbide formed and the α/β ratio in the reaction products were strongly affected by a change of the source of carbon used in the starting mixtures.MST/1346a

Journal ArticleDOI
TL;DR: In this paper, conditions for carbothermal synthesis of α-Si3N4 are presented with special emphasis on the reaction temperature, C:SiO2 ratio, and precursor mixing, with pure precursors, the conversion temperature is 1500° to 1550°C.
Abstract: Conditions for carbothermal synthesis of α-Si3N4 are presented with special emphasis on the reaction temperature, C:SiO2 ratio, and precursor mixing. With pure precursors, the conversion temperature is 1500° to 1550°C. An excess of C is necessary for complete conversion, and a simple sol–gelmixing technique provides excellent intermixing of the precursors. Copious flow of N2 gas throughout the reactor bed is essential if pure Si3N4 is to be produced; small concentrations of CO and O2 promote SiC and Si2N2O, respectively.

Patent
07 Nov 1991
TL;DR: In this paper, the process comprises the sequential formation, on a silicon substrate (1), of a lower layer (2), of silicon oxide, of an intermediate layer (3) of silicon nitride and of an upper layer (4, 15) of polycrystalline silicon, followed by the etching of the latter for the definition of a window having a width greater than that of the desired trench (8).
Abstract: The process comprises the sequential formation, on a silicon substrate (1), of a lower layer (2) of silicon oxide, of an intermediate layer (3) of silicon nitride and of an upper layer (4, 15) of polycrystalline silicon or of silicon oxide, followed by the etching of the latter for the definition of a window (5, 16) having a width greater than that of the desired trench (8). The window (5, 16) is then narrowed down to the width of the desired trench (8) accomplishing some spacers (11) or oxidizing the layer of polycrystalline silicon (15). There is then executed the etching of the substrate (1) inside said narrow window (7, 14, 18) for the accomplishment of the trench (8), followed by the oxidation of the walls of the trench (8) and by its selfplanarization.

Journal ArticleDOI
TL;DR: In this article, the instability mechanism of amorphous silicon-silicon nitride thin-film transistors (TFTs) is examined and it is demonstrated that the instability is caused by an electrical charge stored at the interface between amorphou silicon and silicon nitride.
Abstract: Instability mechanism of amorphous silicon‐silicon nitride thin‐film transistors (TFTs) is examined. By investigating double‐layer insulator TFTs, it is demonstrated that the instability is caused by an electrical charge stored at the interface between amorphous silicon and silicon nitride. The amount of stored charge at the interface (Q) does not depend on either drain voltage or drain current. Study on TFTs with several insulator thicknesses has shown that Q strongly depends on the band bending in the amorphous silicon that is related to the gate electric field (E) through the gate insulator. The Q‐E relationship is found to be a more general expression of the dependence of threshold voltage shift on gate voltage, and is incorporated into a formula suitable for examining the interface quality.

Proceedings ArticleDOI
30 Jan 1991
TL;DR: In this paper, composite LPCVD polysilicon/silicon nitride flexures have been fabricated on the sidewalls of previously patterned poly-silicon mesas by anisotropic reactive-ion etching.
Abstract: Composite LPCVD polysilicon/silicon nitride flexures have been fabricated on the sidewalls of previously patterned polysilicon mesas by anisotropic reactive-ion etching Cantilever beams 450 nm thick (150 nm of silicon nitride and 300 nm of polysilicon) and 25 mu m wide (the mesa height) were fabricated Upon release from the sidewall, the cantilever deflects laterally away from the mesa due to a large built-in bending moment arising from the compressive residual stress in the polysilicon layer and the tensile residual stress in the silicon nitride layer End deflections of about 20 mu m are observed for 70 mu m-long cantilevers This self-adjusting microstructure (SAMS) makes use of residual stresses in thin films to reduce intercomponent clearances or to apply preloads in micromechanical systems The authors present a design theory for SAMS, describe the fabrication process in detail, and discuss the results of initial experiments >

Patent
Mikata Yuuichi1, Takahiko Moriya1
21 Jun 1991
TL;DR: In this article, a method of manufacturing a silicon nitride film on a semiconductor substrate using a low-pressure CVD apparatus, including the steps of setting a plurality of semiconductor wafers in a boat in a reaction furnace was described.
Abstract: According to this invention, there is disclosed a method of manufacturing a silicon nitride film on a semiconductor substrate using a low-pressure CVD apparatus, including the steps of setting a plurality of semiconductor wafers in a boat in a reaction furnace, increasing a temperature in the reaction tube to a predetermined temperature and decreasing a pressure in the reaction tube to a predetermined pressure, and supplying Si(N(CH 3 ) 2 ) 4 gas from a first gas source to the reaction tube and supplying NH 3 gas from a second gas source to the reaction tube.

Journal ArticleDOI
TL;DR: In this article, the influence of selected chemical compounds on the friction and wear of silicon nitride under boundary lubrication conditions was investigated using a ball-on-three-flat modification of the four-ball wear tester.
Abstract: Successful use of advanced ceramics in many tribological applications requires an understanding of the physical, chemical, and mechanical properties of the material. Physical and mechanical data are relatively abundant for most ceramics. However, information on the chemical interactions of ceramics is scarce. This is especially true for chemical interactions with regard to lubrication of these materials. This paper investigates the influence of selected chemical compounds on the friction and wear of silicon nitride under boundary lubrication conditions. A ball-on-three-flat modification of the four-ball wear tester was utilized to evaluate the tribological characteristics of a hot pressed silicon nitride lubricated with a paraffinic base oil containing 1 weight percent additives. Friction, wear, and. film formation tendencies were observed for a range of oil soluble chemical compounds containing oxygen, sulfur, nitrogen, chlorine, and phosphorous. A wide range of additive response was observed. Friction c...

Journal ArticleDOI
TL;DR: In this article, low temperature silicon nitride and oxynitride films were deposited downstream from an electron cyclotron resonance (ECR) plasma source using SiH4 and N2 gas mixtures.
Abstract: Good quality, low temperature silicon nitride and oxynitride films were deposited downstream from an electron cyclotron resonance (ECR) plasma source using SiH4 and N2 gas mixtures. The Si/N ratio and H content in the deposited films were determined using Rutherford backscattering spectrometry and elastic recoil detection. The H concentration was minimum for films with compositions closest to that of stoichiometric Si3N4. The optimum conditions for producing a stoichiometric Si3N4 were a SiH4/N2 flow ratio between 0.1 and 0.2, and an electrically isolated sample far from the ECR source. Infrared absorption spectra showed that as the film composition changed from N rich to Si rich the dominant bonds associated with H changed from N–H to Si–H.