Showing papers on "Silicon nitride published in 1978"

The hydrogen content of plasma‐deposited silicon nitride

Abstract: The hydrogen content of glow‐discharge‐deposited silicon nitride (SiN) films made at 330–350 °C has been determined. Preparation conditions were varied to produce a range of compositions of Si/N=0.7–1.4. Quantitative hydrogen profiling of the samples was carried out using the resonant nuclear reaction 15N+H→12C+4He+γ ray. Calibration factors for Si‐H (2160 cm−1) and N‐H (3350 cm−1) absorption‐band areas or absorbances have also been determined, enabling infrared transmission spectra to be used for hydrogen analyses of these films. All samples were homogeneous in hydrogen content and were in the range (1.6–2.1) ×1022 H atoms/cm3, or about 20–25 at.% H. Roughly three‐quarters of the H is bonded to Si, the remainder to N. One plasma SiO2 sample made at 300 °C from SiH4 and N2O was measured also, and contained 5.7 at.% H, all as OH. Although there was little variation in the H content of SiN, there is a correlation between the total H concentration and the buffered HF etch rate. Some observations on the effects of the 15N ion beam (6–8 MeV) on the SiN are reported. Many Si‐H and N‐H bonds are broken, but the liberated H atoms or ions are unable to diffuse out of the film.

Interactions of ion beams with surfaces. Reactions of nitrogen with silicon and its oxides

Abstract: Ion beam studies of chemical reactions between nitrogen and surfaces of silicon and its oxides are reported. A spectrometer system designed for these studies which combines the techniques of x‐ray and uv photoelectron spectroscopy, Auger electron spectroscopy, secondary ion mass spectroscopy, low energy electron diffraction, and ion bombardment is described. This work employs XPS and UPS to examine the products induced by 500 eV N+2 beams on targets of elemental Si, SiO, and SiO2. The N+2 ions undergo charge exchange and dissociation at the surface of the target to form hot N atoms. Reaction with Si, produces nitrides which are similar to those of the type Si3N4. Reaction with SiO and SiO2 forms nitrides, with no evidence of nitrate or nitrite formation. The chemical nature of the reaction is suggested by identification of the reaction products through XPS and UPS and energy level shifts. The thickness of the silicon nitride layer on Si(111) formed by 500 eV N+2 bombardment has been determined to be ∼19 A thick by using the film/bulk Si XPS intensity ratio. Estimates obtained by depth‐concentration profiling with 1 keV Ar+ and by using LSS projected ion range calculations agree with this approximate thickness.

Hot-pressing and the ?-? phase transformation in silicon nitride

Abstract: The kinetics of densification and the kinetics of theα-β phase transformation have been measured during the hot-pressing of silicon nitride ceramics using magnesia as additive. Two mechanisms of densification have been identified. The first is a very rapid particle rearrangement, liquid-enhanced above 1550° C, which operates up to relative densities of about 0.65. The kinetics of the much slower decelerating second stage obey the Coble hot-pressing equation and the rate of densification is found to be proportional to the amount of additive. The controlling mechanism is believed to be diffusion in a boundary second phase, and values for the diffusion coefficient,D b, of the rate-controlling species in the boundary phase for temperatures above and below 1550° C are given. The kinetics of theα toβ transformation, the greater part of which occurs after densification is complete, are described by a first order reaction; the dependence of rate on the quantity of additive and on temperature is similar to that found for densification, and a similar controlling mechanism is believed to be responsible for the two processes.

The α/β silicon nitride phase transformation

Abstract: The literature on the α/β silicon nitride transformation is reviewed briefly. Data are presented on the kinetics of the tranformation of 1600° C on low and high purity silicon nitride powders. The addition of magnesia increased the rate of transformation while the addition of yttria had no effect. Scanning electron photomicrographs show clearly the morphology changes that accompany the transformation. It is concluded that the transformation occurs via a solution-precipitation mechanism and that α and β are probably low and high temperature forms of silicon nitride.

Processing of crystalline ceramics

Abstract: Keynote Address.- Some Considerations in the State of the Art in Processing Crystalline Ceramics.- I: Fine Particle Science, Technology and Characterization.- Physical and Chemical Parameters Controlling the Homogeneity of Fine Grained Powders and Sintering Materials.- Ultrafine Powders of Oxide and Non-Oxide Ceramic Materials and Their Sinterability.- Handling and Green Forming of Fine Powders.- The Potential of Fine Particle Technology Applied to Ceramic Raw Materials.- Particle Size and Permeability in Slip Casting.- Chemical Processing for Ceramics (and Polymers).- Ceramics Sintered Directly from Sol-Gels.- Characterization of Ceramic Microprocessing.- Packing and Sintering Relations for Binary Powders.- Stress and Density Distributions in the Compaction of Powders.- Pore Morphography in Ceramic Processing.- II: Solid State Sintering and Grain Growth.- Fundamentals of the Sintering of Ceramics.- Current Paradigms in Powder Processing.- Some Effects of Aggregates and Agglomerates in the Fabrication of Fine Grained Ceramics.- The Sintering of Conductive Rutile: A Model System for Sintering Electronic Ceramics.- Sintering of Mullite.- Rate Controlled Sintering as a Processing Method.- A Multiple-Lognormal Model of a Normal Grain Growth.- III: Liquid Phase Sintering And Post-Firing Technology.- Rearrangement During Liquid Phase Sintering of Ceramics.- Reactivity of Alumina Substrates with High Lead Glasses.- Influence of the Processing Parameters on the Properties of Rapid Fired Porcelain.- Strengthening of Lime-Stabilized Zirconia by Post Sintering Heat Treatments.- Strain and Surface Energy Effects in Ceramic Processes.- Dynamic and Material Parameters in Brittle Fracture in Ceramics.- Processing Induced Sources of Mechanical Failure in Ceramics.- IV: Dielectric and Magnetic Ceramics.- Processing of High Density Piezoelectric Ceramic Compositions.- The Role of ZrO2 Powders in Microstructural Development of PZT Ceramics.- Novel Uses of Gravimetry in the Processing of Crystalline Ceramics.- Deformation Processing of Magnetic Hexaferrites for Hc Maximization Through Grain Growth Control.- Processing and Magnetic Properties of Low-Loss and High-Stability Mn-Zn Ferrites.- Relationship Between Processing Conditions, Oxygen Stoichiometry and Strength of MnZn Ferrites.- Sintering of High Density Ferrites.- V: Energy Related Ceramics I: Fast Ion Conductors MHD, Nuclear and Refractory Ceramics.- Processing and Characterization of Polycrystalline ?"-Alumina Ceramic Electrolytes.- Microstructural Control During Sintering of ?"-Alumina Compositions Through Ceramic Processing Modification.- Transient Eutectics in Sintering of Sodium Beta Alumina.- Microstructural Evolution During the Processing of Sodium ?-Alumina.- Fabrication and Performance of MHD Electrodes.- Fabrication and Property Control of LaCrO3 Based Oxides.- Strontium Containing Perovskites and Related Conductive Electronic Ceramics.- Hot Pressed Composite Ceramic MHD Electrode Development.- Processing Variables Affecting the Thermomechanical Degradation of Monolithic Refractory Concretes.- UO2-Gd2O3 Sintering Behavior.- Processing Requirements for Property Optimization of EU2O3-W Cermets for Fast Reactor Neutron Absorber Applications.- Ceramic Processing of Boron Nitride Insulators.- VI: Energy Related Ceramics II: Non-Oxide Ceramics.- Grain Boundary Engineering in Non-Oxide Ceramics.- The Fabrication of Dense Nitrogen Ceramics.- Ceramics in the Si-Al-O-N System Fabricated by Conventional Powder Processing and Sintering Techniques.- Polytypism in Magnesium Sialons.- Dense Silicon Nitride Ceramics: Fabrication and Interrelations with Properties.- High-Pressure Hot-Pressing of Silicon Nitride Powders.- The Structure of Grain Boundaries in Silicon Nitride Based Alloys.- Evolution of Microstructure in Polycrystalline Silicon Carbide.- Thermal Gradient Deposition of SiC Diffusion Tracers.- Contributors.

Microstructure of Y2O3 Fluxed Hot‐Pressed Silicon Nitride

Abstract: Detailed microstructural analysis of a 10 mol% Y/sub 2/O/sub 3/ fluxed hot-pressed silicon nitride reveals that, in addition to the yttrium-silicon oxynitride phase located at the multiple Si/sub 3/N/sub 4/ grain junctions, there is a thin boundary phase 10 to 80 A wide separating the silicon nitride and the oxynitride grains. Also, x-ray microanalysis from regions as small as 200 A across demonstrates that the yttrium-silicon oxynitride, Y/sub 2/Si(Si/sub 2/O/sub 3/N/sub 4/), phase can accommodate appreciable quantities of Ti, W, Fe, Ni, Co, Ca, Mg, Al, and Zn in solid solution. This finding, together with observations of highly prismatic Si/sub 3/N/sub 4/ grains enveloped by Y/sub 2/Si(Si/sub 2/O/sub 3/N/sub 4/), suggests that densification occurred by a liquid-phase ''solution-reprecipitation'' process.

Kinetics of Oxidation of Hot‐Pressed Silicon Nitride Containing Magnesia

Abstract: The oxidation of NC 132 hot-pressed silicon nitride in dry oxygen was studied at 1521 to 1731K. The rate of O2 uptake and N2 release, as a function of time, was measured volumetrically. The ratio of N2 released to O2 consumed was smaller than expected from the stoichiometry of the oxidation reaction for Si3N4. The low value was attributed to impurities in the material. The oxidation rate followed the parabolic law with an activation energy of 440 kJ/mol. The corrosion scales (examined by microsurface techniques) were porous due to bubbles of released N2. The scales consisted of a mixture of unoxidized silicon nitride grains, crystalline oxides (SiO2 and MgSiO3containing other elements), and a glass phase. Reoxidation showed that the oxide scale was not protective. The magnesium profile in the subsurface layers indicated that the diffusion of magnesium in the unoxidized material was the rate-limiting step in the oxidation.

A mechanism for the nitridation of Fe-contaminated silicon

Abstract: The influence of iron impurity on both the oxidation and nitridation of high purity silicon has been investigated. It is shown that iron is effective in rapidly removing the protective silica film which normally covers silicon. Experimental evidence suggests that the removal is achieved by iron-induced devitrification and disruption of the silica, thus allowing the SiO (g) generated by the Si/SiO2 interface reaction to escape. During the nitridation of iron-contaminated silicon powder compacts it is found that iron significantly enhances the extent of reaction for contamination levels of <1000 p.p.m. Fe (by weight). Above this level there is a decrease in the rate of formation of extra nitride. At all levels of contamination the percentage of silicon converted to β-Si3N4 was observed to be directly proportional to the iron concentration, and it is shown that this β-growth occurs within an FeSix liquid phase. The possible implications of the findings for the optimization of strength of reaction-bonded silicon nitride are briefly discussed.

Characterization of Organosilicon‐Infiltrated Porous Reaction‐Sintered Si3N4

Abstract: Polymeric organosilicon compounds such as hexaphenylcyclo-trisilazane and methylphenyl polysilane were used to infiltrate porous reaction-sintered silicon nitride. The in situ thermal decomposition of the infiltrated body under controlled atmosphere and temperature resulted in pronounced changes in the microstructure, increased densities, and significantly improved room-temperature strength. The silicon oxynitride phase present in some as-received materials is eliminated and the ratio of α- to β-phase silicon nitride increases during infiltration processing

Process and material for manufacturing semiconductor devices

Abstract: A process step and material for use in the manufacture of semiconductor devices. To facilitate the etching of unmasked silicon dioxide, silicon nitride, silicon monoxide, bare silicon layers, or various refractory metals on preselected portions of a semiconductor slice, the material is exposed to a low pressure RF generated "cold" plasma (under 325° C.) produced from a homogeneous gaseous binary mixture of oxygen and a halocarbon. The halocarbon is preferably a gas having one carbon atom per molecule and is preferably fully fluorine-substituted.

Film‐edge‐induced stress in silicon substrates

Abstract: Stress fields in silicon substrates, induced by edges of silicon nitride films, were studied by experimentally observing the distribution of indentation‐injected dislocation half‐loops in the vicinity of the film edge. From this distribution, the stress field was obtained by applying the method of analysis recently introduced by the author. The results were compared to the theoretical stress field due to a line force (an approximation) tangential to the boundary of a half‐space, with good agreement.

Very Thin Silicon Nitride Films Grown by Direct Thermal Reaction with Nitrogen

Abstract: Very thin uniform silicon nitride films less than 100A have been obtained on silicon wafers by direct thermal reaction with nitrogen at temperatures ranging from 1200° to 1300°C. Small amounts of water or oxygen in reaction mixture caused vapor etching which gave rise to local crystallization. By eliminating both from the reaction ambient to less than 1 ppm, amorphous silicon nitride films can be deposited. These films have been found to have properties similar to those of CVD by investigations of Auger electron spectroscopy, infrared spectroscopy, and ellipsometry. Remarkable masking effects of the films against oxidation and phosphorus diffusion have been found.

Single component monomer for silicon nitride deposition

Abstract: Method of preparing silicon nitride film by glow discharge from the decomposition of liquid trisilylamine, (SiH 3 ) 3 N, which is a volatile monomer. In this connection, the use of a single monomer as diluted with an inert gas enables greater uniformity to be achieved in the deposition of silicon nitride films. Further, the presence of Si-N bonds in the monomer enables more control and better stoichiometry in the deposited films.

Thermally grown silicon nitride films for high-performance MNS devices

Abstract: Amorphous and uniform silicon nitride films with thicknesses of less than 100 A have been thermally grown on silicon wafers by employing purified ammonia gas. The films are much denser than conventional CVD Si3N4 films. The MNS (metal‐thermal nitride‐silicon) structures have very low Nss in the order of 3×1010 cm−2 eV−1 and an effective electron mobility of larger than 800 cm2/V sec in the fabricated n‐channel MNSFFT.

Electrical properties of the gallium arsenide–insulator interface

Abstract: Extensive capacitance–voltage (C–V) measurements have been performed on three types of insulators on n‐type GaAs: pyrolytically deposited silicon nitride, sputtered silicon nitride, and the oxide produced by anodization. Evaporated aluminum gate contacts and alloyed Au–Ge ohmic contacts were applied and the C–V characteristics of these structures were measured from the quasistatic regime to 150 MHz. Although differences in detail are seen at intermediate frequencies, the data taken at the extreme frequency limits differ very little for the three types of specimens. The quasistatic and high‐frequency data are consistent with a model wherein the surface potential with zero applied gate bias is ∠−0.8 V. Application of electric fields of the order of ±106 V/cm at the semiconductor surface results in movement of the surface potential across approximately 1/3 of the band gap. An accumulation layer of surface electrons could not be produced on any of the devices tested.

The compression creep behaviour of silicon nitride ceramics

Abstract: A comparison has been made of the compression creep characteristics of samples of reaction-bonded and hot-pressed silicon nitride, a sialon and silicon carbide. In addition, the effects of factors such as oxide additions and fabrication variables on the creep resistance of reaction-bonded material and the influence of dispersions of SiC particles on the creep properties of hot-pressed silicon nitride have been considered. For the entire range of materials examined, the creep behaviour appears to be determined primarily by the rate at which the development of grain boundary microcracks allows relative movement of the crystals to take place.

Sodium-assisted oxidation of reaction-bonded silicon nitride

Abstract: The oxidation of reaction-bonded silicon nitride in air, and with small amounts of sodium carbonate applied to the sample surface, has been studied. The action of the alkali is to cause short-term enhanced oxidation,which is terminated when specific compositions of the product sodium silicate glass are attained. These correspond closely to liquidus compositions in the Na2O-SiO2 system, and it is postulated that the retardation in the oxidation rate at this stage is due to the formation of a stable tridymite film at the silicon nitride-glass interface. The implications for the high temperature stability of reactionbonded silicon nitride components in alkali contaminated atmospheres are discussed.

AES and XPS of silicon nitride films of varying refractive indices

Abstract: AES and XPS measurements of silicon nitride films with refractive indices ranging from 1.93 to 2.08 have been made. The films studied were grown on silicon (100) substrates by CVD using varying mixtures of silane and ammonia. Earlier AES studies of similar silicon nitride films have suggested that these films are microscopic mixtures of Si and Si3N4. We present XPS data which show that there is no measurable ’’free’’ silicon (i.e. the level of ’’free’’ silicon is ≲3 at. %) in the silicon nitride films with refractive indices ≲2.02. AES data show an increase in oxygen content corresponding to a decrease in refractive index of the silicon nitride films. These AES measurements agree qualitatively with measurements of the physical properties of silicon oxynitride films.

β'-Sialon sintered body and a method for manufacturing the same

Abstract: This invention provides a method for manufacturing said sintered body, comprising preparing a starting material by adding 10 to 1,000 wt. parts of metal silicon powder to 100 wt. parts of mixed powder composed of 20 to 80 wt. % silica powder and 80 to 20 wt. % aluminium powder and mixing said powders thoroughly, further adding, if required, a refractory fine powder of alumina, silicon nitride, aluminium nitride, β'-sialon, aluminium nitride polytype sialon, or silicon carbide, molding the resultant mixture into a green compact, and then sintering said green compact in a nitrogeneous nonoxidative gas atmosphere at a temperature of 1,200° to 1,550° C. This invention further provides a compact sintered body which will be prepared by the above mentioned method.

Thermal Oxidation Rate of a Si3N4Film and Its Masking Effect against Oxidation of Silicon

Abstract: The thermal oxidation of a silicon nitride film was evaluated at temperatures ranging from 900°C to 1100°C and under water vapor partial pressures ranging from 0.25 atm to 0.95 atm. The oxidation rate was measured by ellipsometry and the results were compared with those of simultaneously oxidized silicon substrates. The conversion ratio, which is the thickness ratio of a grown oxide film to a consumed nitride film, of 1.64 was obtained with small fluctuation. The oxidized nitride thickness xn was found to be proportional to t2/3, where t is the oxidation time. This relationship is consistent with a proposed oxidation model. The figure of merit m was defined as the masking effect of a nitride film. It was found that a large m value was obtained when the film was oxidized at low temperature and under high water vapor partial pressure.

Process for forming a contact region between layers of polysilicon with an integral polysilicon resistor

Abstract: A process for forming an electrical contact region between layers of polysilicon with an integral polysilicon resistor during the fabrication of MOS integrated circuits is disclosed. The contact region which does not require critical alignments, may be formed directly over an active channel or buried (substrate) contact. A silicon nitride mask is formed at the location of the contact region on the first polysilicon layer thereby allowing a thick oxide to be grown on the remainder of the substrate. After removal of the silicon nitride mask, a second polysilicon layer is formed which contacts the first layer at the contact region and defines the resistor. A doping step is used to establish the resistance of the resistor. The process permits the fabrication, by way of example, of a static (bistable) MOS memory cell employing polysilicon loads with an area of approximately 1.5 mils2.

Proof-testing of hot-pressed silicon nitride

Abstract: Proof-testing was investigated as a method for insuring the reliability of hot-pressed silicon nitride in high temperature structural applications. The objective of the study was to determine if the strength distribution of a population of test specimens could be truncated by proof-testing. To achieve this objective the strength of silicon nitride was measured at 25° C and 1200° C, both with and without proof-testing. At 25° C, however, the strength distribution was effectively truncated by proof-test ing. At 1200° C, however, the effectiveness of proof-testing as a means of truncating the strength distribution was determined by the resistance of the silicon nitride to oxidation. Although oxidation removes machining flaws that limit the strength of silicon nitride, long-term exposure to high temperature oxidizing conditions resulted in the formation of surface pits that severely degraded the strength. Provided the effects of high temperature exposure are taken into account, proof-testing is shown to be useful for truncating the strength distribution of hot-pressed silicon nitride at elevated temperatures.

Creep of reaction-bonded silicon nitride

Abstract: The high temperature mechanical properties, mainly the creep behaviour of reaction-bonded silicon nitride (RBSN), a new engineering ceramic for the gas turbine, have been a point of considerable interest. During the recent development a remarkable increase of the creep resistance of RBSN has been reached and the latest data show creep rates of below 10−6 h−1 at 1300° C and 70 to 100 MM m−2. Activation energies between 540 and 700 kJ mol−1 and stress exponents of 1

Atlanta fiber system experiment: Planar epitaxial silicon avalanche photodiode

Abstract: A silicon avalanche photodiode (APD) has been developed for optical fiber communications systems. It has been optimized for optical wavelengths of 800 to 850 nm and exhibits a quantum efficiency greater than 90 percent. The APD operates between typical voltages of 100 and 400 V, exhibiting photocurrent gains of approximately 8 and 100, respectively, at those biases. The device has a short response time of ∼ 1 ns and low excess noise characterized by an excess noise factor approximately 5 times the shot noise limit for operation at a photocurrent gain of 100. The APD has a four-layer n+-p-π-p+ structure and is fabricated on large-diameter epitaxial wafers using planar technology. Uniform avalanche gain, low dark currents, and good reliability are achieved through the use of (i) a diffused guard ring, (ii) a diffused channel stop, (iii) metal field plates, (iv) the removal of impurities in the surface oxides and the bulk of the APD, (v) passivation with silicon nitride and (vi) a processing sequence that maintains low dislocation density material.

Analyses for stoichiometry and for Hydrogen and Oxygen in silicon nitride films

Abstract: Optical, ion, and electron probe techniques can be effectively applied to analyze for H, O, and the Si/N ratio in thin films of silicon nitride. The films studied were formed by chemical-vapor deposition or plasma deposition for application as a gate dielectric in semiconductor memory devices and for circuit encapsulation. The H concentration is measured by the multiple internal reflection technique which detects NH and SiH vibrational modes. A decrease in SiH bonding with an increase in deposition temperature is shown for chemical-vapor-deposited silicon nitride, and a very high concentration of SiH bonds is observed in plasma-deposited silicon nitride. Ion back-scattering analysis is a direct method for measuring the Si/N ratio and a related nuclear reaction analysis technique is a direct method for measuring and profiling the O content. Backscattering analysis shows a significantly larger Si/N ratio for plasma than for chemical-vapor-deposited silicon nitride. The O profile obtained by reaction analysis for a nitride/oxide/Si structure is compared to that obtained by sputter Auger electron spectroscopy, and the results show that O concentrations down to ∼0.5 at % can be measured by either technique. Auger analysis gives better depth resolution than reaction analysis but it requires a calibration standard. Auger results also show N penetration of interfacial SiO 2 and accumulation of N at the Si-SiO 2 interface.

Combination glass/low temperature deposited Si{hd w{b N{HD x{b H{HD y{b O{HD z {b passivating overcoat with improved crack and corrosion resistance for a semiconductor device

Abstract: A semiconductor device having an improved passivating structure comprises a first primary passivating layer free of any layer of silicon nitride (Si3N4), disposed on a surface of a semiconductor body, a metallic conductor disposed on the first passivating layer, and a secondary passivating overcoat disposed over the metallic conductor, wherein the secondary passivating overcoat includes both a glass layer on the conductor and a low-temperature-deposited (typically 300 DEG C) nitride layer on the glass layer. The device is highly resistant to degradation in the presence of water vapor and corrosive atmospheres.

Si{hd 3{b N{HD 4 {B Coated crucible and die means for growing single crystalline silicon sheets

Abstract: Mechanical components, e.g. die and/or crucible or the like structures with which single silicon crystals are grown from the melt as shaped articles in thin sheet or ribbon geometry, are advantageously comprised, for their material of construction, of a suitable thermally stable and inert foundation substrate coated or provided on at least the silicon-contacting surface(s) thereof with a thin, uniform, integral surface layer deposit of pyrolitic silicon nitride (Si3N4) obtained by the chemical vapor deposition (i.e., "CVD") technique.