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Showing papers on "Silicon nitride published in 1993"


Journal ArticleDOI
TL;DR: In this paper, the authors used high-resolution electron microscopy (HREM) to study grain-boundary intergranular films in different Si[sub 3]N[sub 4] ceramics.
Abstract: Silicon nitride materials typically reveal thin amorphous intergranular films along grain boundaries, with only the exception of special boundaries. It is known that such grain-boundary films strongly affect the high-temperature properties of the bulk material. High-resolution electron microscopy (HREM) was used to study these amorphous films in different Si[sub 3]N[sub 4] ceramics. The observed film thicknesses at grain boundaries in these materials varied between 5 and 15 [angstrom]. It was shown that the grain-boundary film thickness strongly depends on film chemistry. Careful inspections of film-thickness measurements across grain boundaries in a given material suggest that the film widths vary on the order of 1 [angstrom]. Therefore, a quantitative evaluation should allow for the determination of the standard deviation of the film thickness. The amorphous film widths along grain boundaries in four materials were measured over the entire length (up to 1 [mu]m) of the grain boundary between two triple points. Forty to fifty data points were evaluated for each boundary, giving a Gaussian-like distribution of the film thickness around a median value, which corresponded well with the film width measured from single HREM micrographs. The accuracy achieved by the statistical method was better than [plus minus] 1 [angstrom].

242 citations


Journal ArticleDOI
TL;DR: In this paper, the electrical properties of silicon nitride/amorphous silicon structures were investigated using thin film transistors (TFTs) and metal insulator semiconductor (MIS) devices employing either a top nitride (TN) or bottom nitride(BN) as gate insulator.
Abstract: The electrical properties of silicon nitride/amorphous silicon structures were investigated using thin film transistors (TFTs) and metal insulator semiconductor (MIS) devices employing either a top nitride (TN) or bottom nitride (BN) as gate insulator. The density of states (DOS) deduced from the subthreshold transfer characteristic of the TFTs is one to two orders of magnitude higher than that obtained from quasistatic C(V) measurements on the MIS structures. This difference is discussed by considering the different thickness of the a‐Si:H layers of the two devices and the role of a fixed charge at the rear interface. Both techniques indicate a DOS in BN devices which is only slightly lower than in TN devices, by less than a factor of two. The measured field effect mobility of BN TFTs is about 70% higher. The differences in the measured field effect mobility for TN and BN configuration are discussed and ascribed to the source and drain parasitic resistances. The conclusion is verified by the fabrication of a TN TFT with a pure phosphine rear surface treatment, which exhibits performance comparable to BN TFTs.

241 citations


Journal ArticleDOI
TL;DR: In this paper, a review of the solid-state chemistry of ternary and higher phosphorus(V) nitrides and the relationship between the various types of structure found in this class of substance and the resulting properties and possible applications is presented.
Abstract: Among the nonmetal nitrides, the polymeric binary compounds BN and Si3N4are of particular interest for the development of materials for high-performance applications. The outstanding features of both substances are their thermal, mechanical, and chemical stability, coupled with their low density. Because of their extremely low reactivity, boron and silicon nitride are hardly ever used as starting materials for the preparation of ternary nitrides, but are used primarily in the manufacture of crucibles or other vessels or as insulation materials. The chemistry of ternary and higher nonmetal nitrides that contain electropositive elements and are thus analogous with the oxo compounds such as borates, silicates, phosphates, or sulfates was neglected for many years. Starting from the recent successful preparation of pure P3N5, a further binary nonmetal nitride which shows similarities with Si3N4 with regard to both its structure and properties, this review deals systematically with the solid-state chemistry of ternary and higher phosphorus(V) nitrides and the relationship between the various types of structure found in this class of substance and the resulting properties and possible applications. From the point of view of preparative solid-state chemistry the syntheses, structures, and properties of the binary nonmetal nitrides BN, Si3N4, and P3N5 will be compared and contrasted. The chemistry of the phosphorus(V) nitrides leads us to expect that other nonmetals such as boron, silicon, sulfur, and carbon will also participate in a rich nitride chemistry, as initial reports indeed indicate.

178 citations


Patent
16 Dec 1993
TL;DR: In this paper, a hydrogen halide plasma is created within an etch chamber and the negative charge at the bottom of the chamber attracts the positively charged plasma, thereby etching the substrate in the downward direction.
Abstract: Silicon dioxide on a substrate is directionally etched using a hydrogen halide plasma which is created within an etch chamber. The method selectively etches silicon dioxide relative to polysilicon and silicon nitride. A substrate and the combination of NH 3 and NF 3 gases or the combination of CF 4 and O 2 gases mixed with H 2 and N 2 gases are located within an etch chamber. An electrical field is created within the etch chamber causing the gas mixture to form a plasma. The negative charge at the bottom of the chamber attracts the positively charged plasma, thereby etching the substrate in the downward direction. The result is an anisotropic product. The method is also shown to be effective in non-selectively etching thermal and deposited oxides, resulting in a similar etch rate for the different types of oxides.

133 citations


Journal ArticleDOI
01 Jun 1993-Wear
TL;DR: In this article, the effect of load and temperature on wear was investigated on a hot isostatically-pressed silicon nitride under various test conditions in self-mated sliding tests in air.

124 citations


Patent
25 Jan 1993
TL;DR: Anisotropic etch as mentioned in this paper employs an anisotropic enchant for silicon such as KOH or ethylene diamine para-catechol, which is done from the backside 12b of the wafer to the front side 12a, and terminates on the dielectric layer on the frontside.
Abstract: An ink fill slot 18 can be precisely manufactured in a substrate 12 utilizing photolithographic techniques with chemical etching. N-type silicon wafers are double-side coated with a dielectric layer 26 comprising a silicon dioxide layer and/or a silicon nitride layer. A photoresist step, mask alignment, and plasma etch treatment precede an anisotropic etch process, which employs an anisotropic etchant for silicon such as KOH or ethylene diamine para-catechol. The anisotropic etch is done from the backside 12b of the wafer to the frontside 12a, and terminates on the dielectric layer on the frontside. The dielectric layer on the frontside creates a flat surface for further photoresist processing of thin film resistors 16.

112 citations


Patent
28 May 1993
TL;DR: In this article, a silicon nitride and silicon oxynitride film of high quality and excellent coating property having no moisture and carbon component in the film was provided to provide a silicon oxide and silicon oxide film.
Abstract: PURPOSE: To provide a silicon nitride and silicon oxynitride film of high quality and excellent coating property having no moisture and carbon component in the film. CONSTITUTION: The inside of a chamber 3 is made into a reduced pressure state about several torr, individual gases to be used for film formation are mixed inside a shower head electrode 4 for being introduced from the shower head electrode 4 into the chamber 3. High frequency voltage is impressed between the shower head electrode 4 and a lower part electrode 1 from high frequency power supply 12 so as to make gas mixed by the shower head electrode 4 inside the chamber 3 and to cause chemical reaction for forming a reactive intermediate. A film having an excellent coating property on a substrate 2 by this reactive intermediates. As reactant gas, trisilylamine 6 and ammonium gas are used when a nitride film is formed and when an oxynitride film is formed, nitrogen suboxide (N 2 O) gas is used in addition to trisilylamine 6 and ammonium gas. COPYRIGHT: (C)1994,JPO

106 citations


Journal ArticleDOI
TL;DR: In this paper, Fourier transform infrared spectroscopy was used in the transmission mode to monitor the surface chemistry of both treated and untreated porous-silicon samples before and after exposure to humid air at room temperature.
Abstract: Resistance to room temperature oxidation and control over wetting properties can be achieved by chemical modification of a porous‐silicon surface. Fourier transform infrared spectroscopy was used in the transmission mode to monitor the surface chemistry of both treated and untreated porous‐silicon samples before and after exposure to humid air at room temperature. Surface modification methods investigated include: (i) vapor‐phase silation using either hexamethyl‐disilazane or trimethylchlorosilane, and (ii) rapid thermal annealing in nitrogen, ammonia, or argon ambients. The silation treatments, carried out in the presence of trace moisture, were successful both in creating surface trimethylsilyl groups and in suppressing room temperature oxidation. Rapid thermal annealing at temperatures as low as 500°C for 30 s eliminates all silicon hydrides. Nitrided porous‐silicon layers are formed at 1100°C in either ammonia or nitrogen; in both cases the silicon nitride infrared absorption peaks scale with the porous layer thickness, indicating that the compounds are distributed throughout the porous layer.

105 citations


Patent
08 Jul 1993
TL;DR: In this paper, a method using NF 3, mixed with an electropositive diluent, preferably argon, at a given range of concentration, pressure, flowrate, and power to obtain the fastest possible etch rates is presented.
Abstract: A method has been developed for the removal of silicon nitride and silicon dioxide, or other semiconductor materials from a surface of a wafer or CVD reactor. The method uses NF 3 , mixed with an electropositive diluent, preferably argon, at a given range of concentration, pressure, flowrate, and power to obtain the fastest possible etch rates. The etch rates of the film being processed can be caused to increase even as the concentration of NF 3 in the diluent is decreased by choosing the proper diluent and operating conditions. Not only does this method increase the etch rate, thereby increasing the throughput of the reactor using this process, it also accomplishes this task at low concentrations of NF3 resulting in a lower cost.

97 citations


Journal ArticleDOI
TL;DR: In this article, the authors explored the nature of the silicon dangling-bond center in amorphous hydrogenated silicon nitride (a•SiNx:H) thin films, and its relationship to the charge trapping centers using electron paramagnetic resonance (EPR) and capacitancevoltage (C•V) measurements.
Abstract: We have explored the nature of the silicon dangling‐bond center in amorphous hydrogenated silicon nitride (a‐SiNx:H) thin films, and its relationship to the charge trapping centers using electron paramagnetic resonance (EPR) and capacitance‐voltage (C‐V) measurements. We have investigated the quantitative relationship between the concentration of silicon dangling bonds using EPR and the concentration of charge traps, measured by C‐V measurements, for both UV‐illuminated and unilluminated a‐SiNx:H thin films subjected to both electron and hole injection sequences. A theoretical framework for our results is also discussed. These results continue to support a model in which the Si dangling bond is a negative‐U defect in silicon nitride, and that a change in charge state of preexisting positively and negatively charged Si sites is responsible for the trapping phenomena observed in these thin film dielectrics.

95 citations


Journal ArticleDOI
TL;DR: In this article, transient creep was found to dominate the high-temperature behaviour of a grade of hot isostatically pressed silicon nitride containing only 4 wt% Y2O3 as a sintering aid.
Abstract: Transient creep is shown to dominate the high-temperature behaviour of a grade of hot isostatically pressed silicon nitride containing only 4 wt% Y2O3 as a sintering aid. Contributing factors to transient creep are discussed and it is concluded that the most likely cause of longterm transient creep in the present study is intergranular sliding and interlocking of silicon nitride grains. In early stages of creep, devitrification of the intergranular phase, and intergranular flow of that phase may also contribute to the transient creep process. The occurrence of transient creep precluded the determination of an activation energy on the as-received material. However, after creep in the temperature range 1330–1430°C for times exceeding approximately 1100 h, an apparent activation energy of ≈ 1260 kJ mol−1 was measured. It is suggested that the apparent activation energy for creep is determined by the mobility and concentration of diffusing species in the intergranular glassy phase. The time-to-rupture was found to be a power function of the minimum strain rate, independent of applied stress or temperature. Hence, creep-rupture behaviour followed a Monkman-Grant relation. A strain rate exponent of − 1.12 was determined.

Patent
15 Feb 1993
TL;DR: In this article, an intrinsic hydrogenated amorphous silicon semiconductor layer is formed in the thickness of 100nm by the plasma CVD method and the excimer laser is cast on the sample to crystallize it.
Abstract: PURPOSE: To obtain a polycrystalline silicon semiconductor film which has an excellent electric characteristic by a method wherein a hydrogenated amorphous silicon film is formed at low temperatures and is heat-treated in a vacuum and then it is dehydrogenated to generate a dangling bond in the film and the excimer laser is cast on the film in a vacuum-unbroken state. CONSTITUTION: An SiO 2 film or silicon nitride film is formed as a base protective film 12 on a glass substrate 11. Nextly, an intrinsic hydrogenated amorphous silicon semiconductor layer 13 is formed in the thickness of 100nm by the plasma CVD method. At that time, by setting the film formation temperature low, the formed amorphous silicon film is allowed to have in it a good quantity of water and bonds of silicon are neutralized with hydrogen as much as possible. Nextly, a device separation patterning is conducted and the sample is heated in a vacuum at 450°C for one hour to be dehydrogenated completely and dangling bonds (unpaired bonds) are generated in high density in the film. With the vacuum state being maintained, the excimer laser is cast on the sample to crystallize it. COPYRIGHT: (C)1993,JPO&Japio

Patent
18 Jun 1993
TL;DR: In this paper, the gate oxide and a gate electrode are formed on the surface of a silicon substrate and source and drain regions are ion implanted into the silicon substrate using the gate electrode as a mask.
Abstract: A process for suppressing hot electrons in sub half micron MOS devices wherein a gate oxide and a gate electrode are formed on the surface of a silicon substrate and source and drain regions are ion implanted into the silicon substrate using the gate electrode as a mask. The process includes forming a layer of silicon dioxide over the gate electrode and over the source and drain regions of the substrate, and then introducing a barrier layer forming element into the layer of silicon dioxide to form a thin barrier region to hot electrons at the interface between the silicon substrate and the silicon dioxide. In a preferred embodiment of the invention, nitrogen is introduced into the silicon dioxide by heating the wafer in a rapid thermal processor and in the presence of a nitrogen containing gas at an elevated temperature for a predetermined time. The nitrogen containing gas may be selected from the group consisting of nitrogen trifluoride, ammonia and nitrous oxide. In an alternative embodiment of the invention, fluorine atoms are introduced into the silicon substrate either as the sole barrier layer forming element (silicon fluoride) or prior to the formation of the thin silicon nitride region. The fluorine atoms form good strong silicon-fluorine bonds in the silicon substrate and thereby further enhance the hot electron suppression. In a third embodiment, nitrogen and fluorine are reacted in a rapid thermal processor to form a composite barrier layer of Si3 N4 and SF.

Patent
07 Dec 1993
TL;DR: In this paper, a silicon nitride-based cutting tool for high speed chip forming machining of metallic materials is described, where the tool has a rake face (30) joined to flank faces (50) by cutting edges.
Abstract: Provided is a silicon nitride based ceramic which is particularly useful for use as a cutting tool (10) in the high speed chip forming machining of metallic materials. The ceramic is preferably composed of at least 85 volume percent (v/o) beta silicon nitride phase and less than about 5 v/o intergranular phase. The ceramic has greater than 0.2 weight percent (w/o) magnesia, greater than 0.2 w/o yttria, where the sum of magnesia and yttria is less than 5 w/o. The ceramic has less than 0.2 v/o porosity. The tool (10) has a rake face (30) joined to flank faces (50) by cutting edges (70).

Journal ArticleDOI
TL;DR: In this paper, the chemistry of glow discharge plasmaenhanced chemical vapor deposition (PECVD) was studied by using vibrating quartz crystal deposition rate monitoring at 200-300°C and line-of-sight mass spectrometry of orifice-sampled reactive neutral species.
Abstract: We have studied the chemistry of glow discharge plasma‐enhanced chemical vapor deposition (PECVD) by using vibrating quartz crystal deposition rate monitoring at 200–300 °C and line‐of‐sight mass spectrometry of orifice‐sampled reactive neutral species. In the deposition of dielectric films from silane plus a large excess of oxidant (NH3, N2, or N2O), the key process factor is the ratio of plasma power to silane supply rate. When enough of the oxidant is activated by the plasma, it completely converts the silane to films which have no excess Si and no Si–H bonding. The critical ratio can be detected by the disappearance of Si2H6 byproduct or by the presence of excess activated oxidant. Nitride deposited from N2 is electrically leaky due to porous microstructure even when deposited using excess activated oxidant. Conversely, nitride deposited from NH3 is nonporous, and when deposited using excess activated oxidant it has a surprisingly low electron trapping rate which is at least as low as that achievable ...

Journal ArticleDOI
13 Apr 1993-Wear
TL;DR: In this paper, a series of ball-on-ring wear tests was performed on sintered silicon nitride and it was found that at the lowest speed that was used, the wear rate at low humidity was higher than that for higher humidity.

Journal ArticleDOI
TL;DR: In this article, the authors observed the simultaneous creation of paramagnetic Si and N dangling bonds when N•rich silicon nitride thin films are optically illuminated at low temperatures (110 K).
Abstract: We observe the simultaneous creation of paramagnetic Si and N dangling bonds when N‐rich silicon nitride thin films are optically illuminated at low temperatures (110 K). Generally, only the Si dangling bond is observed if the illumination is performed at room temperature. In contrast, the N dangling bond is metastable, and has previously only been observed after a high temperature post‐deposition anneal and followed by illumination. We propose that the low temperature illumination causes two processes: (1) Charge conversion of N3≡Si+ and N3≡Si− sites to give two N3≡Si⋅dangling bonds, and (2) charge transfer between Si2=N− and N3≡Si+ sites to form Si2=N⋅ and N3≡Si⋅dangling bonds.

Patent
16 Mar 1993
TL;DR: In this paper, a low pressure chemical vapor deposition process for silicon nitride can be used to achieve a deposition rate of up to 185 angstroms per minute with a gas mixture including a silane precursor gas and ammonia.
Abstract: Thin, uniform films of silicon nitride can be deposited onto a single substrate in a low pressure chemical vapor deposition process at a practicable rate from a gas mixture including a silane precursor gas and ammonia by maintaining the pressure at between about 5 and about 100 Torr. Deposition rates of up to about 185 angstroms per minute are readily achieved.

Journal ArticleDOI
TL;DR: In this paper, the formation of reaction-bonded silicon nitride (RBSN) compacts has been studied and it was shown that β-Si3N4 formation does not necessarily require a liquid phase, and atomic nitrogen stimulates β-phase formation.
Abstract: Several salient factors influencing the formation of reaction-bonded silicon nitride (RBSN) compacts have been studied. These include the effects of mullite and alumina furnace tubes typically employed during “high-purity” nitridation studies, pre-sintering of green silicon compacts, free powder versus compact nitridation, and the influence of metal/metal oxide additions. The latter studies have provided experimental evidence for enhancement due to dissociated nitrogen, and suggest that (1) β-Si3N4 formation does not necessarily require a liquid phase, (2) atomic nitrogen stimulates β-phase formation, and (3) the liquid phase provides an efficient source for volatile silicon, promoting α-Si3N4. These conclusions are consistent with accepted mechanisms for the formation of the two phases.

Journal ArticleDOI
TL;DR: In this paper, microstructural development and crystallization behavior of Yb2O3-fluxed sintered silicon nitride materials were investigated using CTEM and HREM.
Abstract: Microstructural development and crystallization behaviour of Yb2O3-fluxed sintered silicon nitride materials was investigated using CTEM and HREM. The materials contained 5 and 10 vol% Yb2O3 as sintering additives. After densification, both compositions were subsequently heat treated to crystallize the residual amorphous secondary phases present at triple-grain regions. In the material doped with 5 vol% Yb2O3, only an amorphous secondary phase was observed after sintering, which was about 80% crystalline (Yb2Si2O7) after the post-sintering heat treatment. A metastable phase was formed in the material with 10 vol% additives after sintering, with about 70% crystallinity in the triple-point pockets. Upon postsintering heat treatment, the material could be completely crystallized. During heat treating, the metastable phase combined with the remaining glass to form Yb2SiO5 plus Yb2Si2O7 and a small amount of Si3N4 which deposited epitaxially on pre-existing Si3N4 grains in areas of low-energy within the triple-point pockets. All materials contained thin amorphous films separating the grains. The amorphous intergranular films along grain boundaries (homophase boundaries) revealed excess ytterbium and oxygen. The thickness of the intergranular films was about 1.0 and 2.5 nm for the grain boundaries and the phase boundaries, respectively, independent of additive content and heat-treatment history.

Patent
05 Mar 1993
TL;DR: In this paper, the fabrication of diaphragm pressure sensors utilizing silicon-on-insulator technology where recrystallized silicon forms a diaphram which may incorporate electronic devices used in monitoring pressure.
Abstract: The present invention relates to the fabrication of diaphragm pressure sensors utilizing silicon-on-insulator technology where recrystallized silicon forms a diaphragm which may incorporate electronic devices used in monitoring pressure. The diaphragm is alternatively comprised of a silicon nitride having the necessary mechanical properties with a recrystallized silicon layer positioned thereon to provide sensor electronics.

Journal ArticleDOI
TL;DR: In this article, the synthesis and structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied.
Abstract: The synthesis and the structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied. SiC-Si[sub 3]N[sub 4] composite ultrafine particles were prepared by irradiating a SiH[sub 4], C[sub 2]H[sub 4], and NH[sub 3] gas mixture with a CO[sub 2] laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt% carbon and 5.8 wt% nitrogen, had a [beta]-SiC structure. As the nitrogen content increased, SiC decreased and amorphous phase, Si[sub 3]N[sub 4], Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.

Journal ArticleDOI
TL;DR: The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride.
Abstract: The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride. The review encompasses corrosion in diverse environments, usually at temperatures of 1000 °C or higher. The environments include dry and moist oxygen, mixtures of hot gaseous vapors, molten salts, molten metals, and complex environments pertaining to coal ashes and slags.

Patent
06 Jul 1993
TL;DR: In this article, an anti-reflective layer of silicon-rich silicon nitride was used for photoresist pattern notching over reflective materials on a semiconductor substrate, which was then photolithographically patterned to form an integrated circuit pattern.
Abstract: Reflective notching of a photoresist pattern (20), generated over reflective materials on a semiconductor substrate (12), is minimized by using an anti-reflective layer (20) of silicon-rich silicon nitride. The layer of silicon-rich silicon nitride is formed over the reflective materials and a layer of photoresist is then formed over the silicon-rich silicon nitride. The photoresist layer is then photolithographically patterned to form an integrated circuit pattern (20). The silicon-rich silicon nitride layer has an absorptive index of greater than 0.25, which allows it to be used as an anti-reflective layer with photolithographic patterning systems having ultraviolet and deep ultraviolet exposure wavelengths.

Journal ArticleDOI
TL;DR: In this article, the authors compared PECVD silicon nitride films to low pressure chemical vapor deposited (LPCVD) films and investigated the dependence of the film properties on process parameters, specifically power and temperature.
Abstract: The qualities of plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films can be improved by increasing the deposition temperature. This report compares PECVD silicon nitride films to low pressure chemical vapor deposited (LPCVD) films. The dependence of the film properties on process parameters, specifically power and temperature, are investigated. The stress is shown to shift from tensile to compressive with increasing temperature and power. The deposition rate, uniformity, wet etch rate, index of refraction, composition, stress, hydrogen content, and conformality are considered to evaluate the film properties. Temperature affects the hydrogen content in the films by causing decreased incorporation of N-H containing species whereas the dependence on power is due to changes in the gas-phase precursors. All PECVD film properties, with the exception of conformality, are comparable to those of LPCVD films.

Journal ArticleDOI
TL;DR: In this paper, a method was developed to bond 3-inch borosilicate sputter-coated silicon wafers to silicon wafer coated either with aluminium, silicon dioxide, polysilicon or silicon nitride.
Abstract: Silicon to silicon wafer bonding by use of sputter deposited borosilicate film is a promising mounting method for micromechanical components. This method has been developed to bond 3 inch borosilicate sputter coated silicon wafers to silicon wafers coated either with aluminium, silicon dioxide, polysilicon or silicon nitride. The bondings were performed at temperatures ranging from 300 to 400 °C which enables application of this technique on metallised devices. The bond strengths of the different samples bonded with these methods are all in the region 5–25 MPa. Some samples were exposed to water for 300 h to test the media compatibility, and some samples were thermal shock tested by repeatedly exposing to liquid nitrogen. No significant difference in bond strength has yet been verified statistically for the different sample configurations. We have also observed good correlation between destructive bond strength testing and non-destructive infrared microscope inspection.

Patent
05 Mar 1993
TL;DR: In this paper, a fiber-reinforced ceramic matrix composite of complex shape is made by first rigidifying a fibrous arrangement made of woven or braided material by impregnating with a preceramic resin, and then curing and pyrolyzing the resin to form a rigid or stiff preform.
Abstract: A method of making a fiber-reinforced ceramic matrix composite of complex shape by first rigidifying a fibrous arrangement made of woven or braided material by impregnating with a preceramic resin, and then curing and pyrolyzing the resin to form a rigid or stiff preform. The rigid preform is then densified by chemical vapor infiltration, e.g., using a forced-flow/thermal-gradient process. Using three-dimensional woven fabrics made of ceramic fibers, such as silicon carbide or silicon nitride, strong high-temperature resistant composites are produced having porosities from about 20 percent to less than about 5 percent.

Journal ArticleDOI
TL;DR: An interconnection structure using a TiN/Al-1% Si-0.5% Cu/TiN/Ti multilayer conductor was investigated as a quarter-micrometer interconnection candidate for 256-Mb DRAMs as discussed by the authors.
Abstract: An interconnection structure using a TiN/Al-1% Si-0.5% Cu/TiN/Al-1% Si-0.5% Cu/TiN/Ti multilayer conductor was investigated as a quarter-micrometer interconnection candidate for 256-Mb DRAMs. It was found that intermetallic compounds such as TiAl/sub x/ were formed at both grain boundaries of Al-Si-Cu and interfaces between Al-Si-Cu and TiN of the multilayer, resulting in both increase in Vickers hardness and suppression of stress relaxation. The multilayer conductor strip, which was covered with plasma-enhanced chemical vapor deposition silicon nitride (P-SiN), suppressed stress-induced voiding after heat treatment at 500 degrees C. Electromigration tests for quarter-micrometer wide multilayer strips indicated the improvement in the mean time to failure and the increase of the standard deviation. >

Journal ArticleDOI
TL;DR: In this paper, a single-crystal gallium arsenide (SC-GaAs) actuator was designed, fabricated, and operated using chemically assisted ion beam etching and reactive ion etching (RIE).
Abstract: Submicron, single-crystal gallium arsenide (SC-GaAs) actuators have been designed, fabricated, and operated. The fabrication process, called SCREAM-II (single crystal reactive etching and metallization II), uses chemically assisted ion beam etching (CAIBE) and reactive ion etching (RIE) to produce suspended and movable SC-GaAs structures with up to a 25:1 aspect ratio of vertical depth (10 mu m) to lateral width (400 nm). Integrated actuators with predominantly vertical sidewall (PVS) aluminum electrodes are used to move the structures. Silicon nitride is used as an etch mask, structural stiffener, and electrical insulator. An x-y stage with integrated actuators produces controllable x-y displacements of +or-1.8 mu m when a voltage of 54.5 V is applied to either or both of the x and y actuators. The x-y stage resonates for an applied sinewave of 20 V (peak to peak) with f=10.5 kHz and a DC offset of 10 V. The structural vibration amplitude is 0.6 mu m. >