Showing papers on "Silicon nitride published in 1971"

Characterization of Silicon Nitride Films

Abstract: Various "silicon nitride" films have been prepared from , N2, , and in an rf‐promoted glow discharge reaction. These films are described primarily through the use of infrared absorption. Aided by ultraviolet absorption, the inclusion of excess silicon or of oxygen in the films is readily followed. Changes in index of refraction, etch rates in HF acid, and electrical conductivity of the films are correlated with the optical absorption study. Comparisons of these films with those formed by pyrolysis or by reactive sputtering are made. Some reproducible physical properties of an amorphous film are stated.

Microstructural studies on silicon nitride

Abstract: Thin specimens of reaction sintered and hot pressed silicon nitride have been prepared by ion beam thinning and examined in the Harwell million volt microscope. It has been found that reaction sintered material consists of large grains, which are mostlyβ-Si3N4, in a fine grained matrix ofα-Si3N4. Fibres are frequently observed within the pores, the type of fibre depending on the size of the pore. The hot pressed material consists largely of two types of grain, small angular grains ofβ-Si3N4 and larger irregular grains. There is also some non-crystalline material between the angular grains and there are numerous small unidentified inclusions. The grains ofβ-Si3N4 generally contain dislocations and examination of these shows that most have a 〈0001〉 Burgers vector. The remaining dislocations appear to be more complex, frequently occurring as multiple images, and have not been unambiguously identified. An analysis of dislocations inβ-Si3N4 shows that 〈0001〉 dislocations are the most stable and are also likely to be most mobile with {10¯10} as the primary slip plane.

Mass of polycrystalline cubic system boron nitride and composites of polycrystalline cubic system boron nitride and other hard materials, and processes for manufacturing the same

Abstract: This invention gives bonded or compact bodies of polycrystalline cubic system boron nitride and substantially uniform composites of polycrystalline cubic system boron nitride and other hard materials, for example, metal borides, such as titanium boride and zirconium boride, covalent or metallic cabides, such as boron carbide, silicon carbide, titanium, carbide, tungsten carbide and chromium carbide, metal nitrides, such as titanium nitride, tantalum nitride, silicon nitride and aluminum nitride, metal oxides, such as alumina and silica, complex oxide such as garnet and agate, and diamond. Further, this invention provides a process of obtaining the bonded body of these materials which comprises subjecting hexagonal system boron nitride powder, or a mixture of hexagonal system boron nitride powder and cubic system boron nitride crystal powder or powders of the above-mentioned hard materials to high temperatures and high pressures.

Heat resistant and strengthened composite materials and method for producing same

Abstract: Heat resistant and strengthened composite materials are obtained by mixing, and sintering in a non-oxidizing atmosphere, the combination of powders of aluminum nitride and/or silicon nitride, with powders of an oxide of lanthanum, cerium, scandium, yttrium, and/or yttrium aluminum garnet, and with powders or whiskers of silicon carbide, boron nitride and/or carbon. The composite material so produced is characterized by high shock resistance and excellent mechanical strength.

Conversion of silicon nitride into silicon dioxide through the influence of oxygen

Abstract: When thin films of silicon nitride are annealed in the presence of oxygen, thin films of silicon dioxide are formed on the nitride layers while silicon nitride is consumed. The thickness of the oxide layers which are built up by reaction with dry oxygen, wet oxygen and by a mixture of oxygen and nitrogen in the presence of phosphorus pentoxide, are given as a function of time and temperature. The results are compared with the thermal oxidation of silicon.

Evaluation of Silicon Nitride Layers of Various Composition by Backscattering and Channeling‐Effect Measurements

Abstract: Composition and density of silicon nitride layers deposited on silicon by the NH3–SiH4 reaction at 850°C were measured as a function of the reaction components. Backscattering and channeling‐effect measurements with MeV 4He ions were used to determine the depth dependence of the concentration ratio of nitrogen to silicon and density. The compositions of the silicon nitride layers were stoichiometric with densities approximately 3.0 g/cm3 for NH3/SiH4 deposition ratios greater than 10. For lower ratios, the concentration of nitrogen decreased and that of silicon increased. The variation of the concentration ratio of nitrogen to silicon follows the variation in the physical and electrical properties of the layers.

Silicon nitride-silicon oxide etchant

Abstract: This invention discloses a chemical to etchant and a process for chemically etching silicon nitride-silicon oxide composite structure which may be used, for example in microelectronic devices. The etching process or system utilizes a mixture of phosphoric acid and a fluoborate anion containing compound such as fluoboric acid. The etch rate of the silicon nitride relative to the etch rate of the silicon oxide can be controlled to the desired etch rate by varying the temperature of the etchant and/or adjusting the ratio mixture of the phosphoric acid and the fluoboric acid.

Silicon nitride products

Abstract: A method of manufacturing silicon nitride products is of the kind in which silicon nitride powder is pressed at an elevated temperature to form the product, the pressing being continued until the product is fully densified. The method is characterised in that the fully densified product is then heated further at a temperature sufficient to convert alpha -phase silicon nitride to beta -phase silicon nitride.

Silicon nitride ceramic composites with high toughness.

Abstract: THE brittleness of ceramic materials, compared with metals, limits their use in engineering, in spite of such attractive properties as high temperature strength and oxidation resistance. Possible solutions to the brittleness problem therefore continue to be of interest. One approach advocated1 for silicon nitride has been that of fibre reinforcement, practical feasibility of which has been demonstrated2. In the carbon/silica system Crivelli-Visconti3 and Cooper have shown that high work of fracture can be obtained : we present here mechanical property data for silicon nitride/silicon carbide fibre composite materials. The potential of silicon nitride ceramics as engineering materials has been described elsewhere4.

Electrical Properties of Gold at the Silicon-Dielectric Interface

Abstract: The influence of gold has been examined at the Si/SiO2 interface, and it has been found that the results are consistent with gold introducing an acceptor surface state close to the valence band edge. A study of the formation kinetics of these centers has indicated that they result from a surface‐reaction‐limited process rather than from a gold diffusion‐rate‐limited process. It is suggested that the surface reaction is between the gold and interfacial disorder centers, such that the density and availability of these centers determine the resulting density of active gold centers. Gold has also been found to introduce the same type of acceptor center at the interface between silicon and deposited layers of both silicon nitride and silica. Finally, a number of other metals were examined for action similar to gold at the Si/SiO2 interface. Only platinum was found to behave in this manner, and it was assumed that the same mechanism was operative in the formation of this center as with the gold centers.

Silicon nitride ceramics

Abstract: Shaped ceramic objects of silicon nitride are protected from oxidation by a coating comprising silica and boric oxide. The coating may be formed by heating a shaped mixture of silicon nitride and boron nitride in air to convert part to silica and boric oxide and causing a silica/boric oxide glass to flux and protect the object from further oxidation. The boron may be incorporated during oxidation but is preferably added to the silicon before nitriding.

The Selective Epitaxial Growth of Silicon by Using Silicon Nitride Film as a Mask

Abstract: The selective epitaxial growth of Si through the window in silicon nitride film is studied for the SiCl4-H2 system. Experiments prove that the silicon nitride film is extremely stable compared with the usual silicon dioxide film. To find out the necessary conditions for the selective epitaxial growth, the growth rates of Si on silicon nitride film and on silicon bare surface are obtained independently from the experiment. The critical SiCl4 pressure for the nucleation on silicon nitride film is determined as a function of growth temperature. The experimental results are explained by the nucleation theory.

Semiconductor device having a composite film as a passivating film

Abstract: A semiconductor device having a composite film as a passivating film formed on the surface of the device in the order of films of silicon oxide formed by thermal oxidation, phosphorous glass, silicon oxide formed by chemical vapor deposition and silicon nitride, whereby cracks, which occurs in the film when the phosphorous glass film is in contact with the silicon nitride film, can be eliminated.

Insulated gate field effect transistor circuits and their method of fabrication

Abstract: Insulated gate field effect transistor circuits utilizing transistors having a self-aligned gate, reduced parasitic capacitance and lower surface step-heights are fabricated with three levels of interconnects. The self-aligned gate transistors are fabricated with the use of a silicon nitride diffusion mask which also serves as an oxidation barrier in the formation of a thick oxide over the source and drain regions. Diffused interconnects are formed simultaneously with the source and drain region diffusions. The silicon nitride is then replaced with a more suitable dielectric, followed by the formation of polycrystalline silicon interconnects to provide source, drain and gate electrodes, and to provide a second level of interconnects which cross over the diffused interconnects at desired locations. An insulating layer is formed over the silicon interconnects and a metallization interconnect pattern, which crosses over the silicon interconnects at various desired locations is then formed to complete the circuit.

Investigation of the Composition of Sputtered Silicone Nitride Films by Nuclear Microanalysis

Abstract: The composition and uniformity of silicon nitride thin films deposited by reactive sputtering in a mixture of argon and nitrogen eventually contaminated by oxygen traces were studied. Both direct observation of nuclear reactions on nitrogen and oxygen and backscattering of 4He+ ions were used to analyze the deposits. The films appear uniform as a function of depth. They are practically oxygen free but contain large amounts of argon. Their stoichiometry changes with the partial pressure PN2 of nitrogen. The ratios N/Si and Ar/Si vary in the opposite direction; for smaller values of PN2 there is an excess of silicon, whereas for larger values an excess of nitrogen is observed with respect to the stoichiometric composition Si3N4.

Method of producing silicon nitride articles

Abstract: A method of producing a silicon nitride article comprising forming an article as a compact of silicon powder, sintering the silicon compact in an atmosphere substantially free of nitrogen, machining the silicon compact to a required accuracy, and nitriding the machined silicon compact to produce the silicon nitride article.

Silicon nitride as an antireflection coating for semiconductor optics.

Abstract: Semiconductors are known to exhibit large reflection losses due to their large index of refraction (3 < n < 4) in the spectral region of optical transparency. Consequently, very substantial gains in transmission coefficient of multisurfaced optical elements can be obtained by the use of antireflection coatings. In the course of other investigations, it was noted that the index of silicon nitride might provide an excellent optical match to the index of several commonly used semiconductors, by closely satisfying the well-known square-root condition for quarter-wave films, i.e., if

On the hysteresis and memory properties of the silicon-silicon nitride system

Abstract: A close examination of the hysteresis experienced in the C-V curves and of the memory properties of MNS capacitors has been made. Both the gate and the silicon inject carriers into the nitride giving hysteresis curves which change in sense as the bias sweep-frequency is reduced. From these measurements it was seen that the trapping time constants in the silicon nitride were much slower for holes than for electrons, and that there is a distribution of traps throughout the nitride which contribute to the hysteresis phenomenon. The movement of the C-V curves along the bias axis was found to vary somewhat depending upon whether an oxide layer was present between the silicon and the silicon nitride. Switching was difficult without the oxide present but very stable, with a thin oxide present switching was easier but instabilities existed, and with a thick oxide present no switching occurred at all. At low temperatures there was absolutely no movement of the C-V curves even at very high voltages (≃ 100 V). From the measurements it may be concluded that the traps causing the hysteresis are different from the traps causing the switching.

Improvements in and relating to electrodeposition of composite materials

Abstract: 1,224,166. Electro-depositing composite coatings; electro-forming. BRISTOL AEROJET Ltd. March 21, 1969 [Dec.21, 1967], No.28598/67. Heading C7B. In a method of electro-depositing coatings consisting of a metal matrix and included fibres of less than one inch length and having a similar orientation to one another, relative movement is provided during electro-deposition between the substrate to be coated and the electrolyte in the direction of desired orientation of the fibres. The process may be used for coating articles or for producing articles by electro-forming. The fibres may be of carbon, graphite, silicon carbide, silicon nitride, boron nitride, beryllium, tungsten or boron, and may be metal plated prior to use, and the matrix may be of nickel, cobalt, tin, copper or aluminium. The substrate may be of steel, of a non-ferrous or light alloy, or of plastics, glass, or composited materials rendered conductive by incorporation of a conductive material therein or by pre-coating with a conductive material. In the form shown a tubular componant 9 to be coated is suspended from a hollow rotary shaft 12 in an electrolytic bath 7 within container 1 having a concical bottom section 2. Electrolyte is circulated by means of suction tube 5, pump 3 and feed tube 4 in order to maintain the fibres in suspension. A cathode 8 is provided adjacent the wall of the container 1, and the workpiece 9 and stirrer 18 are rotated about supporting shafts 12, 17 by means of drive belts 14, 20 and pulley wheels 13, 19 respectively. Spiral electrolyte flow may be induced by introducing the electrolyte tangentially. The component to be coated may be degreased with trichloroethylene or acetone, areas masked which are not to be plated, and cleaned mechanically, e.g. with alumina shot, or with an acid pickle. Examples relate to deposition of carbon fibres in a cobalt matrix using a calicobagged cobalt anode and electrolyte comprising cobalt sulphate, sodium chloride and boric acid; and to deposition of silicon carbide whiskers in a nickel matrix using a rolled nickel anode and electrolyte comprising nickel sulphamate, nickel chloride and boric acid.

Silicon nitride artefacts

Abstract: INCREASED STRENGTH IS IMPARTED TO POROUS SILICON NITRIDE BY SUBJECTING THE SILICON NITRIDE TO CONTROLLED OXIDATION SUCH THAT THE SURFACE OF THE INTERNAL PORES ARE OXIDIZED

The Resistance of Silicon Nitride Ceramics to Thermal Shock and Other Hostile Environments

Abstract: The properties of Si3N4 ceramics relevant to thermal shook are described, and results of testing and hardware trials discussed. The technology of Si3N4 materials, and their potential for other hostile environments, is reviewed.

Silicon nitride kiln furniture

Abstract: A device or item of kiln furniture for the conveyance of silicon wafers into and out of a diffusion furnace in the manufacture of silicon diodes. The device is made essentially of high purity silicon nitride and consists of an elongated base with rotatable wheels attached thereto, and supporting means for carrying silicon wafer laden silicon nitride or silicon boats. The device, by virtue of its design and material of which it is composed, satisfies the peculiar and stringent requirements of silicon diode manufacture, by virtue of the devices ability to retain its integrity through repeated thermal shock, its chemical purity, and its non-dust generating character.

Method of producing a pair of silicon

Abstract: A METHOD OF PRODUCING A PLURALITY OF INTERCONNECTED SILICON NITRIDE PARTS COMPRISES THE STEPS OF STARTING WITH A FIRST SILICON NITRIDE PART, PROVIDING ON SAID FIRST PART A MIXTURE OF SILICON NITRIDE, WHICH IS SUBSTANTIALLY IN THE A-PHASE, AND UP TO 25% BY WEIGHT OF A FLUXING AGENT, AND HOT PRESSING THE MIXTURE OF SILICON NITRIDE AND THE FLUXING AGENT ONTO THE FIRST PART SO AS TO PRODUCE A SECOND, HOT PRESSED SILICON NITRIDE PART INTERCONNECTED WITH THE FIRST PART.

Method of forming integrated semiconductor devices with iii-v compounds

Abstract: THE DISCLOSURE RELATES TO INTEGRATED SEMICONDUCTOR DEVICES FORMED WITH III-V COMPOUNDS. AS AN EXAMPLE, A GALLIUM ARSENIDE SUBSTRATE IS COATED WITH A LAYER OF SILICON DIOXIDE PRIOR TO THE APPLICATION OF A MASKING LAYER OF SILICON NITRIDE. THE SILICON DIOXIDE LAYER PASSES THE ZINC DIFFUSANT BUT PREVENTS LATERAL DIFFUSION SPIKES. THIS PROCESS IS PARTICULARLY USEFUL FOR FORMING AN ARRAY OF CLOSELY SPACED LIGHT EMITTING DIODES.

Semiconductor device or monolithic integrated circuit with tungsten interconnections

Abstract: The tungsten interconnections are coated with platinum where leads are to be attached. The device or circuit is sealed with a layer of silicon nitride or other protective insulating material which has no openings at or near the P-N junctions which extend to the surface of the semiconductor chip.

Integrated circuit including field effect transistor and cerment resistor

Abstract: A single integrated circuit chip includes a field effect transistor having an insulating layer of silicon nitride covering an interface between a silicon substrate and a silicon oxide layer. A thin film cermet resistor on the nitride layer is connected to an ohmic contact of a field effect transistor electrode.