Showing papers on "Silicon nitride published in 1986"

Plasma deposited thin films

Abstract: This book presents a discussion of the mechanisms and practice of plasma deposition with particular emphasis on significant materials produced by this technique, and their applications Materials discussed include hydrogenated amorphous silicon and its alloys, amorphous carbon, and the critically important insulators such as silicon nitride, carbide, and oxide In addition, a review is given, with extensive references, of many other potentially useful materials A major theme of this book is the interrelationship between the process, the authors' understanding of the properties of materials, together with device fabrication and ultimate performance Over 150 figures complement the text

Deposition of silicon dioxide and silicon nitride by remote plasma enhanced chemical vapor deposition

Abstract: We have developed a low temperature process for the deposition of thin films of silicon dioxide and silicon nitride. The process consists of four steps: (a) excitation of an oxygen or nitrogen‐containing molecule in an RF plasma; (b) transport of the excited oxygen or nitrogen species out of the plasma region; (c) mixing of the transported excited species with silane (or disilane) out of the plasma region to form precursor species; and (d) a CVD reaction at a heated substrate to form the desired thin film. We call this process remote plasma enhanced CVD (RPECVD). Silicon rich oxide films have been grown at substrate temperatures (Ts) between 100 and 350 °C using an excited O2/He mixture. Two different ‘‘silicon nitrides’’ have been deposited depending on the excited gas, NH3 or an N2/He mixture, and Ts. Using either nitrogen source and Ts greater than 450 °C, we obtain near stoichiometric films of Si3N4. On the other hand, films grown from NH3 and deposited with Ts of about 50 to 100 °C are silicon diimid...

Programmable low-impedance anti-fuse element

Abstract: An electrically programmable low impedance circuit element is disclosed having capacitor-like structure with very low leakage before programming and a low resistance after programming The electrically programmable low impedance circuit element of the present invention includes a lower conductive electrode which may be formed of a metal or semiconductor material, an insulating layer, which, in a preferred embodiment includes a first layer of silicon dioxide, a second layer of silicon nitride and a third layer of silicon dioxide An upper electrode formed of a metal or of a semiconductor material of the same conductivity type of the lower electrode or a sandwich of both completes the structure

Selectively formable vertical diode circuit element

Abstract: A programmable low impedance interconnect diode element is disclosed having a lower electrode formed of a semiconductor material of a first conductivity type covered by an insulating dielectric layer which may be in a preferred embodiment comprised of an initial layer of silicon dioxide, a second layer of silicon nitride and a third layer of silicon dioxide, covered by a layer of semiconductor material of a second conductivity type A programmable read only memory array and a programmable logic array comprising a plurality of the above-described cells are also disclosed

Sealed cavity semiconductor pressure transducers and method of producing the same

Abstract: Sealed cavity structures suitable for use as pressure transducers are formed on a single surface of a semiconductor substrate (20) by, for example, deposit of a polycrystalline silicon layer (32) from silane gas over a relatively large silicon dioxide post (22) and smaller silicon dioxide ridges (27) leading outwardly from the post. The polysilicon layer is masked and etched to expose the outer edges of the ridges and the entire structure is then immersed in an etchant which etches the silicon dioxide forming the ridges and the post but not the substrate (20) or the deposited polysilicon layer (32). A cavity structure results in which channels (35) are left in place of the ridges and extend from communication with the atmosphere to the cavity (36) left in place of the post. The cavity (36) may be sealed off from the external atmosphere by a second vapor deposition of polysilicon or silicon nitride, which fills up and seals off the channels (35), or by exposing the substrate and the structure thereon to an oxidizing ambient which results in growth of silicon dioxide in the channels sufficient to seal off the channels. Deflection of the membrane spanning the cavity occurring as a result of pressure changes, may be detected, for example, by piezoresistive devices formed on the membrane.

Surface Characterization of Silicon Nitride and Silicon Carbide Powders

Abstract: The nature and composition of the surfaces of silicon nitride and silicon carbide powders were investigated using high voltage and high resolution transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). An amorphous oxide (or oxygen-rich) layer, approx. =3-5 nm thick, present on the powder surfaces forms strong bridges between particles. Both XPS and SIMS show that oxygen is the major impurity on the powder surfaces, but minor impurities such as chlorine, fluorine, carbon, iron and sodium are also revealed. The extent of the oxide layer was reduced substantially by washing the powder in anhydrous hydrofluoric acid or by treatment in an argon/hydrogen gas mixture at approx. =1300/sup 0/C. Surface treatment in the gas mixture did not cause further agglomeration of the powder.

Silicon nitride and silicon diimide grown by remote plasma enhanced chemical vapor deposition

Abstract: We discuss the deposition of silicon nitride (Si3N4) and silicon diimide [Si(NH)2] thin films by remote plasma enhanced chemical vapor deposition (RPECVD). We show that the use of two different nitrogen source gases N2 and NH3 leads to qualitatively different local bonding in the deposited films. We present studies of the local chemical bonding as a function of the substrate temperature (Ts) and the dilution of the nitrogen containing species with the rare gases Ar and He. We show that diluting the N2 with He by a factor of about 10 to 1 increases the growth rate for thin film formation by a factor of more than 3. Dilution of NH3 with He, reduces the deposition rate and also the amount of bonded hydrogen.

Plasma‐enhanced growth and composition of silicon oxynitride films

Abstract: Silicon oxynitride films with varying oxygen/nitrogen ratio were grown from SiH4, N2O, and NH3 by means of a plasma‐enchanced chemical vapor deposition process. The elemental composition of the deposited films was measured by a variety of high‐energy ion beam techniques. To determine the chemical structure we used Fourier transform infrared absorption spectroscopy and electron‐spin resonance. Ellipsometric data and values for mechanical stress are also reported. We show that the entire range of compositions from silicon oxide to silicon nitride can be covered by applying two different processes and by adjusting the N2O/NH3 gas flow ratio of the respective processes. It is suggested that the N2O/SiH4 gas flow ratio is the major deposition characterization parameter, which also controls the chemical structure as far as the hydrogen bonding configuration is concerned. We found that the films contain significant amounts of excess silicon and that the mechanical stress in the oxynitrides is lower than in plasm...

A silicon-thermopile-based infrared sensing array for use in automated manufacturing

Abstract: This paper describes a new low-cost infrared detector array that has been realized using standard silicon MOS process technology and micromachining. This array uses thermopiles as infrared detecting elements and multiple layers of silicon oxide and silicon nitride for diaphragm windows measuring 0.4 mm × 0.7 mm × 1.3 µm. Each thermopile consists of 40 polysilicon-gold thermocouples. A high fill factor for this array structure has been achieved by using the boron etch-stop technique to provide 20-µm thick silicon support rims. The array shows a response time of less than 10 ms, a responsivity of 12 V/ W; and a broad-band input spectral sensitivity. The process is compatible with silicon MOS devices, and a 16 × 2 staggered array with on-chip multiplexers has been designed for applications in process monitoring. The array theoretically achieves an NETD of 0.9°C and an MRTD of 1.4°C at a spatial frequency of 0.2 Hz/mrad in a typical imaging system.

The electronic properties of plasma‐deposited films of hydrogenated amorphous SiNx (0<x<1.2)

Abstract: We present the results of a comprehensive series of measurements on glow‐discharge (plasma) ‐deposited silicon nitride films SiNx:H, with x in the range 0

Preparation and Sintering of Homogeneous Silicon Nitride Green Compacts

Abstract: Interactions between silicon nitride particles and hydroxide precipitates were investigated using electrophoresis measurements Conditions under which stable suspensions of silicon nitride particles and flocculation and heteroflocculation of silicon nitride/hydroxide mixtures occur were Identified On the basis of the observations, a method for producing uniform mixtures of silicon nitride powders and additive precipitates was formulated and used to produce green compacts of improved compositional homogeneity The effect of the mixing process on the sintering of green silicon nitride compacts was investigated and compared to the sintering behavior of conventionally prepared green compacts The results show that the improved homogeneity obtained using the precipitation mixing process leads to enhanced sintering of the green compacts

Eprom with ultraviolet radiation transparent silicon nitride passivation layer

Abstract: An erasable programmable read only memory (EPROM) integrated circuit device 2 having a topside passivation layer 9 of silicon nitride which is transparent to ultraviolet radiation is disclosed. The refractive index of the silicon nitride film is in the range of 1.93±0.03.

Multilayer semi-insulating film for hermetic wafer passivation and method for making same

Abstract: A film for hermetically passivating monocrystalline silicon includes sequential layers of undoped amorphous silicon, oxygen doped polycrystalline silicon, silicon rich oxynitride, and silicon nitride, and may be overlaid with an organic bulk dielectric such as polyimide The inorganic film accurately sets the monocrystalline surface Fermi potential, independent of ambient electrical, mechanical, thermal, ionic, and moisture conditions A method for depositing the amorphous silicon and the oxygen doped polycrystalline silicon layers of the film includes sequentially reacting monosilane in an inert carrier gas, such as helium or argon, and nitrous oxide The layers are blended by varying the deposition temperature, the nitrous oxide flow rate, the monosilane flow rate, the monosilane dilution, and the inert carrier gas species The layers are annealed to locally segregate the oxygen, to grow the grains to the proper size, and to set the final recombination velocity of the monocrystalline region

Microscopic size, thermal conductivity type, air or gas absolute pressure sensor

Abstract: A microscopic size absolute pressure sensor for air or gas of the thermal conductivity type, a silicon nitride covered silicon microchip has an elongated V-groove anisotropically etched in the silicon with a heated silicon nitride bridge element extending over the surface of the V-groove.

Silicon nitride protective coatings for silvered glass mirrors

Abstract: A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate before metal deposition to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors.

Low temperature plasma nitridation process and applications of nitride films formed thereby

Abstract: A silicon nitride layer is prepared on the surface of a silicon substrate by carrying out a surface reaction on the substrate in a vacuum chamber that contains an electrode which is capacitively coupled to an rf generator. A second electrode within the chamber, or a metal wall of the chamber itself, is connected to ground. The silicon substrates to be treated are placed on one of the electrodes to be in electrical and physical contact therewith, and a reagent gas that contains nitrogen is introduced into the chamber. An rf voltage is then applied between the electrodes to ionize and activate the gas, and cause ions and other active species thereof to be directed into the silicon substrate. The nitrogen ions and other active species that are created as a result of the application of the rf power can be directed at the surface of a number of wafers simultaneously. The thin nitride films that are formed by the process have application both as barriers for device isolation and as dielectric components of electrical devices.

Micro-diaphragm pressure sensor

Abstract: A micro-diaphragm pressure sensor with silicon nitride diaphragm of 80 µm × 80 µm was fabricated by applying micromachining technique. The main feature is that it is a complete planar type pressure sensor formed by single-side processing solely on the top surface of

Friction and Wear of Hot Pressed Silicon Nitride and Other Ceramics

Abstract: An investigation was conducted to determine the friction and wear characteristics of hot-pressed silicon nitride. Sliding produced wear debris and a damaged surface. The physical and crystallographic morphology of surfaces was compared with that of diamond ground surfaces. Wear tests were done with pin-on-disk apparatus at a load of 10N with various sliding speeds to 780 mm/s, and in four different environments which included in dry nitrogen, in air at humidities of 50 percent RH and 90 percent RH, and in distilled water. The results of the wear experiments indicated that residual α-silicon nitride was transformed into β-silicon nitride. Adsorbed water appeared to enhance plastic flow of the surface and reduced both the wear rate and friction. A second investigation was conducted to correlate the coefficient of friction with the fracture toughness of silicon nitride, silicon carbide, aluminum oxide and zirconium oxide. The friction experiments were done in reciprocating sliding, using spherical diamonds. Two tip radii, 0.005 mm and 0.1 mm were used over a range of load of 0.1 to 3N and a speed of 0.17 mm/s. The coefficient of friction was found to be inversely correlated with fracture toughness of all four ceramics in several conditions. Frictional anisotropy was also observed in the hot-pressed silicon nitride.

Alumina composite body and method for its manufacture

Abstract: An alumina composite body comprising a plurality of elongated alumina elements oriented in random directions and interconnected so as to constitute a porous matrix, and aluminum and silicon tightly filling the porous matrix; and a method of manufacturing an alumina composite body comprising reacting a body of silica, or a body of a silicon compound such as silicon carbide or silicon nitride which has been at least partially oxidized to produce silica, with aluminum so as to change the silica into alumina.

Valence-band electronic structure of silicon nitride studied with the use of soft-x-ray emission.

Abstract: We have studied the valence-band electronic structure of \ensuremath{\alpha}-phase, \ensuremath{\beta}-phase, and amorphous silicon nitride samples, using Si L-x-ray emission. Our results are compared with a recent band-structure calculation and show that Si 3d states are necessary to properly describe the upper-valence-band and lower-conduction-band density of states. A prominent feature is seen above the valence band which is attributed to conduction-band states that are populated by the incident electron beam. By reducing the energy of the electron beam it is possible to enhance the surface emission relative to bulk emission, and such spectra are also presented and discussed.

Trench filling and planarization process

Abstract: A process for forming planar trench oxide isolated integrated circuit devices. In particular, the process fills trenches of diverse widths, yet provides a final structure in which the narrow trench dielectrics, the wide trench dielectrics, and the active region surfaces are substantially coplanar. Furthermore, the process reduces the likelihood of creating voids in the narrow trenches. According to one practice, following the formation of the trenches in the substrate, successive layers of conformal silicon nitride, conformal polysilicon, and relatively conformal CVD oxide are formed to the relative depth of the trenches. A photoresist mask is then first selectively formed over the central regions of the wide trenches and then used as a mask during the anisotropic etch of exposed oxide. The underlying polysilicon layer serves as an oxide etchant stop, and also provides the material from which the next successive oxidation partially fills the previously etched regions with thermal silicon dioxide. A further planarizing layer of oxide is then formed by poly deposition and oxidation. The nitride layer underlying the polysilicon layer prevents oxidation of the substrate. Fabrication is concluded with a planarization to the level of the active regions, including an etch of the nitride layer over such active regions.

Fast and slow states at the interface of amorphous silicon and silicon nitride

Abstract: The effects of a graded composition layer at the amorphous silicon/nitride interface are studied using transient photoconductivity. The graded layer causes a large increase in the density of slow states (electrons trapped within the nitride), but does not influence the fast interface states. The kinetics of trapping and release are measured and a model of field assisted hopping and thermal excitation is proposed. The different origins of slow and fast states are also discussed.

Method of forming multiple nitride coating on silicon

Abstract: In an integrated circuit process a composite dielectric layer is formed on a monocrystalline, polycrystalline or amorphous silicon substrate by thermally growing a first silicon nitride layer from a surface layer of the silicon and then depositing a layer of amorphous or polycrystalline silicon. A second nitride layer is thermally grown from the deposited silicon to form a nitride-silicon-nitride, termed nitsinitride, composite dielectric. At least a top layer of the nitsinitride dielectric can be oxidized to produce an alternative composite dielectric, termed oxidized nitsinitride. Variation of the thickness of the dielectric layers and/or repeating the layering process sequence results in composite dielectrics of different thicknesses and dielectric properties.

Electron heating in silicon nitride and silicon oxynitride films

Abstract: The vacuum emission technique has been used to study electron transport and heating in silicon nitride and silicon oxynitride. The experimental results are compared to data for silicon dioxide in which all the conduction‐band electrons can gain several eV of energy at electric fields greater than 2 MV/cm. Although average electron energy as a function of electric field curves are very similar to silicon dioxide, the total number of electrons which can be heated to energies greater than 2 eV is greatly reduced because of the increased trapping in these films. Reduction in hot electrons due to increased trapping is correlated to increasing nitrogen content through the oxynitride phases to silicon nitride. Trapping/detrapping on energetically shallow sites in the forbidden gap controls the bulk limited conduction in these films, and very few electrons are allowed to move freely in the conduction band.

Low temperature silicon nitride CVD process

Abstract: Thermal CVD process for forming Si 3 N 4 -type films on substrates by reaction of gaseous NF 3 with gaseous disilane at a temperature in the range of 250°-500° C., at pressures of 0.1-10 Torr. The mole ratio of NF 3 to silane is in the range of 0.5-3.0 and the reaction zone is preferably isothermal (T controlled to within + 5° C.). The resulting films have RI's in the range of 1.4 to 3.0. The process parameters can be controlled to dope the film with H and/or F, or to create zones of differing properties within the film. The process does not cause radiation damage, metal migration, stored charge dissipation or high levels of impurities. Control of distance between adjacent wafers and wafer-to-wall spacing combined with laminar gas flow gives excellent film thickness uniformity, on the order of below about ±5% across the wafer face, both within (across) wafers and from wafer to wafer (batch uniformity).

Programmable read only memory using a tungsten fuse

Abstract: An electrically programmable memory cell using selectively deposited tungsten on a sidewall to define a fuse region. Fabrication of the fuse structure involves only a single mask departure from standard MOSFET processing during which a selective isotropic etch of a silicon nitride sidewall structure facilitates the formation of a fuse structure comprised of a tungsten layer selectively deposited on exposed silicon and a source/drain diffusion separated by an oxide or selectively thinned oxide as the degenerating element. The actuation region of the fuse is proportional to the thickness of the selectively deposited tungsten layer.

Variation of Hydrogen Bonding, Depth Profiles, and Spin Density in Plasma‐Deposited Silicon Nitride and Oxynitride Film with Deposition Mechanism

Abstract: The initial transient phenomenon in plasma processing, an intrinsic and unstable phenomenon of the glow discharge, is found to be the probable cause of the hydrogen‐poor and silicon‐rich structure and the silicon nitride(or oxynitride)‐silicon substrate interfaces of all plasma‐deposited films. A simple and qualitative model was developed to explain the variation of the interface composition of the film with this transient phenomenon. Fourier transform infrared and electron spin resonance measurements suggest the existence of a "stable" amorphous silicon oxynitride composition in films prepared by plasma‐enhanced chemical vapor deposition processing.