Showing papers on "Silane published in 1989"

Control of silicon network structure in plasma deposition

Abstract: Controllability of the Si network structure ranging from amorphous to microcrystalline, polycrystalline, or epitaxial growth has been achieved in conventional glow discharge of silane by controlling the extent of hydrogen ‘etching’ during film growth. The concept of film formation as a balance between deposition and ‘etching’ of the growing surface is discussed. Since energetically unfavorable configurations are preferentially eliminated, ‘etching’ reduces the temperature required to remove weak or strained bonds and produces device quality a-Si:H. It is also responsible for achieving low temperature crystallinity.

Present and future applications of amorphous silicon and its alloys

Abstract: Thin films of amorphous silicon (a-Si:H) and its alloys prepared by the glow discharge decomposition of silane and appropriate gases, are presently incorporated into six commercial products and approximately twenty other applications have been proposed for these materials. This presentation will review the present applications and a number of those proposed for the future. Finally, some of the material and technological issues of current importance will be discussed.

Antimicrobial superabsorbent compositions and methods

Abstract: An antimicrobial superabsorbent composition of a cross-linked hydrophilic sodium salt form of a partially neutralized acrylic acid-based polymer gel having covalently bonded thereto a silane. The composition can be in the form of flakes, strips, powders, filaments, fibers, or films, and may be applied to a substrate in the form of a coating.

Evaluation of surface treatments for glass fibers in composite materials

Abstract: The thermomechanical stability of a number of organosilane surface treatments for glass fibers was evaluated for use in a fiber reinforced epoxy resin. All of the silane coatings were found to improve the tensile strength of E-glass filaments, particularly at large gauge lengths. A phenylamino silane and an amino silane were particularly effective in this regard. The fiber/matrix interface was evaluated as a function of temperature and after exposure to boiling water using a single-fiber composite test. All silane coatings transmitted a higher interfacial shear stress than obtained in composites with no coatings, and in all cases the shear stress transmission was considerably higher than would be expected from the yield properties of the resin. Measurements of the glass transition temperature of the epoxy resin, as well as Fourier-Transform Infra-Red analysis, indicated modification of resin properties in a zone around the glass fibers. Each of the silane coatings provided more stable thermomechanical properties than those obtained with uncoated glass, at least until the silanes were irreversibly degraded by boiling water. A phenylamino silane provided the most thermally stable properties. Finally, unidirectional E-glass fiber reinforced laminae were fabricated and the measured values of longitudinal strength were compared favorably to theoretical predictions.

Synthesis and characterization of a hydride-modified porous silica material as an intermediate in the preparation of chemically bonded chromatographic stationary phases

Abstract: A novel synthetic approach to produce chemically bonded silica-based chromatographlc statlonary phases Is presented and discussed. The procedure involves the Preparation of a silica Intermediate containing stable slllcon hydride (silane) surface specles followed by the cataiytlc addltlon of these to organic compounds bearing a terminal vinyl group. Thls paper deals with the preparation of the hydride intermedlate via chlorination of sllica followed by reduction with llthlum tetrahydrldoaiuminate. Several spectroscopic and thermoanalytlcal technlques were used to obtain Information regarding the structural characterlstlcs of the surface-reduced sllica material. It was found that the surface SIH specles formed were hydrolytlcaily stable at low pH and thermally stable in the presence of oxygen at temperatures up to about 450 OC. Postreaction treatment of the hydride-derivatlred solid with aqueous hydrochloric acid was also found to be essential to remove aluminum byproducts from the silica surface while presumably increasing the extent of silane formation.

Metastable silane hydrolyzates and process for their preparation

Abstract: The present invention provides a relatively simple synthesis procedure for the formation of silane hydrolyzate compositions of the formula ##EQU1## where R is hydrogen or a methyl group, n is an integer greater than about 8, and x is a number between 0 and 2. The hydrolyzate compositions are metastable in solvent solution but become insoluble after coating on a substrate. The resins are useful as planarizing coatings for substrates such as electronic devices and can be ceramified by subjecting them to an oxidizing atmosphere at a temperature of between about 100° to 1000° C. to form ceramic or ceramic-like coatings on such substrates.

Method for selective deposition of refractory metals on silicon substrates and device formed thereby

Abstract: Selective deposition of a refractory metal on a silicon substrate utilizing high temperature and a silane reduction process in which the flow rate ratio of silane to refractory metal halide gas is less than one. In a second embodiment, an additional layer of the refractory metal is deposited utilizing a hydrogen reduction of the metal halide gas at very high temperatures. In both embodiments, a refractory metal barrier layer may be provided by forming a self-aligned refractory metal silicide layer. Alternatively, a two layer self-aligned barrier is formed of a refractory metal silicide lower layer and a refractory metal nitride upper layer and the refractory metal is selectively deposited on the metal nitride.

Mechanical properties of BIS-GMA resin short glass fiber composites.

Abstract: The use of short glass fibers as a filler for dental restorations or cement resins have not been examined extensively. The mechanical properties and untreated glass fibers (5 microns dia x 25 microns) in Bis-phenol A glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) resin were investigated for possible use as a restorative dental composite or bone cement. Compression, uniaxial tension and fracture toughness tests were conducted for each filler composite mixtures of 40, 50, 60 and 70%. Set time and maximum temperature of polymerization were determined. The results show that the elastic modulus, tensile strength and compressive strength are dependent on the percent of filler content. Elastic modulus and compressive yield (0.2%) strength of silane treated glass fibers filled composite increased from 2.26 to 4.59 GPa and 43.3 to 66.6 MPa, respectively, wtih increasing the filler content while the tensile strength decreased from 26.7 to 18.6 MPa. The elastic modulus of the untreated composite was less than that of the silane treated fiber composite. The tensile strength and compressive strengths were 20 to 50% lower than those of silane treated composites. The fracture toughness of the silane treated glass fiber additions were not significantly different from the untreated additions. The highest fracture toughness was obtained at 50% filler content with 1.65 MPa m.5. Set time increased from 3.5 to 7.7 minutes with increased filler content and peak temperature dropped from 68.3 to 34 degrees C. The results of this study indicate that the addition of silane coated glass fiber to BIS-GMA resin increased the elastic modulus, tensile and compressive strengths compared with non-treated fibers. The addition of either treated or non-treated fibers increased the set time of the material and decreased the maximum temperature.

Surface hydrogen content and passivation of silicon deposited by plasma induced chemical vapor deposition from silane and the implications for the reaction mechanism

Abstract: A systematic study of the enhanced concentration of hydrogen in the near surface layer of silicon deposited from silane by plasma induced chemical vapor deposition is presented as a function of temperature and ion bombardment of the surface during growth. The passivation effect of the chemisorbed hydrogen towards oxidation of the surface is documented, and a possible explanation is suggested in terms of a donatorlike effect of that hydrogen to underlying silicon. It is shown that the rate limiting step in the composite reaction mechanism of the deposition of high‐quality silicon films is the ion bombardment induced dehydrogenation of the surface of the growing film. A critical value of substrate bias of −100 eV with respect to the floating potential at which radiation induced damage of the growing film commences is found experimentally. The corresponding ion impact energy agrees very well with Monte Carlo calculations using the TRIM code.

Chemical Vapor Deposition of Epitaxial Silicon from Silane at Low Temperatures I . Very Low Pressure Deposition

Abstract: The deposition of epitaxial silicon films at temperatures from 600°–800°C by both very low‐pressure chemical vapor deposition (VLPCVD) and plasma‐enhanced chemical vapor deposition (PECVD) has been examined. The VLPCVD deposition process is first order in silane partial pressure, zero order in hydrogen partial pressure, and exhibits a low, 8–12 kcal/ mole, activation energy for temperatures from 700°–800°C with 1–15 mtorr silane and hydrogen. For temperatures below 700°C an activation energy of 40 kcal/mole is observed. The growth rate depends upon surface orientation, decreasing in the order (100), (111), polycrystalline, indicating surface processes are rate controlling. The low activation energy regime is associated with a process controlled by silane adsorption and decomposition on a sparsely covered silicon surface. The higher activation energy regime is thought to reflect growth under conditions of high surface coverage with silane fragments and the transition temperature is thought to be pressure dependent. Conditions for the deposition of device quality epitaxial silicon at low temperatures are defined and discussed. Plasma enhancement of the VLPCVD process is discussed in a companion paper.

Permeability controllable membranes. 11. Polymerized monolayers of single-, double-, and triple-chain silane amphiphiles and permeation control through the monolayer-immobilized porous glass plate in an aqueous solution.

Abstract: Polymerisation d'une couche monomoleculaire du distearyl silane a l'interface air-eau de la sous-phase acide et transfert du polymere sur une plaque de verre poreux auquel il est lie par les atomes de silicium. La permeation de NaCl et d'une sonde fluorescente a travers le verre est controlee par la transition de phase de la couche monomoleculaire

In situ investigation of the optoelectronic properties of transparent conducting oxide/amorphous silicon interfaces

Abstract: Transparent conducting oxide (TCO)/hydrogenated amorphous silicon (a‐Si:H) interfaces are investigated combining kinetic ellipsometry and Kelvin probe measurements. It is shown that the correlation between both in situ techniques allows a detailed description of the optoelectronic behavior of these interfaces. The Schottky barrier at the TCO/a/Si:H interfaces, as revealed by Kelvin probe measurements, is correlated with the chemical reduction of the TCO surface during the early stage of a:Si:H growth, as evidenced by kinetic ellipsometry. In particular, indium tin oxide (ITO) and SnO2 are found to be reduced by the silane plasma at 250 °C. On the countrary, ZnO is found highly resistant upon plasma reduction. The influence of the substrate temperature during a‐Si:H deposition is analyzed. Finally, the technical consequences of this study are outlined.

Buffered silane emulsions for rendering porous substrates water repellent

Abstract: There are provided aqueous emulsions useful for rendering porous substrates water repellent comprising (a) a hydrolyzable silane having a determinable pH-stable range, (b) an emulsifying agent having an HLB value of from 2 to 20, an effective amount of (c) a buffering compound to maintain the composition within the pH-stable range; and (d) water. Such buffered compositions are stable on long term storage and maintain high effective levels of active silane content even when they include biocides which may accelerate the hydrolysis of aqueous silane-containing compositions.

A real time ellipsometry study of the growth of amorphous silicon on transparent conducting oxides

Abstract: In situ fast kinetic ellipsometry is used to investigate the early stage of the growth of hydrogenated amorphous silicon (a‐Si:H) on tin‐doped indium oxide (ITO), tin oxide (TO), and zinc oxide substrates. Transparent conducting oxide (TCO) substrates obtained from various sources and deposited by different techniques are studied. A wide range of deposition parameters of a‐Si:H films is considered. For a comparison with growth of amorphous silicon from silane, the ellipsometry data on pure hydrogen plasma degradation of TCO surfaces are also presented. In case of ITO and TO films, a two‐step deposition is observed: the first step is dominated by the reduction of TCO and formation of metallic In or Sn (≊10 s time scale) and the second step is the subsequent growth of a‐Si:H on the reduced substrates. In contrast, ZnO does not show any reduction. The substrate temperature during a‐Si:H deposition is found to have the most important influence on the chemical reduction of the substrates. Variations of other d...

Deposition of silicon oxide films using alkylsilane liquid sources

Abstract: A chemical vapor deposition process for depositing silicon dioxide comprising the steps of heating a substrate upon which deposition is desired to a temperature of from about 325° C. to about 700° C. in a vacuum having a pressure of from about 0.1 to about 1.5 torr, and introducing a silane selected from the group consisting of alkylsilane, arylsilane and araylkylsilane wherein the alkyl-, aryl- or aralkyl- moiety comprises from 2-6 carbons, and oxygen or carbon dioxide into the vacuum.

Homoepitaxial films grown on Si (100) at 150 °C by remote plasma‐enhanced chemical vapor deposition

Abstract: Low‐temperature silicon epitaxy is critical for future generation ultralarge scale integrated circuits and silicon‐based heterostructures. Remote plasma‐enhanced chemical vapor deposition has been applied to achieve silicon homoepitaxy at temperatures as low as 150 °C, which is believed to be the lowest temperature reported to date. Critical to the process are an in situ remote plasma hydrogen cleaning of the substrate surface in an ultrahigh vacuum growth chamber prior to epitaxy, and substitution of thermal energy by remote plasma excitation via argon metastables and energetic electrons to dissociate silane and increase adatom mobility on the surface of the silicon substrate. Excellent crystallinity with very few defects such as dislocations and stacking faults is observed.

Method of producing carbon-doped amorphous silicon thin film

Abstract: A method of producing a carbon-doped amorphous silicon thin film upon a substrate comprising the steps of growing a carbon-doped amorphous silicon layer by plasma assisted chemical vapor deposition, including generating a glow discharge in a gaseous mixture of a silane gas and a hydrocarbon gas, and exposing said carbon-doped amorphous silicon layer to a plasma in a gas containing hydrogen to achieve a resultant layer having a prescribed value of photoconductivity.

Polypropylene-Wood Fiber Composites: Effect of Fiber Treatment on Mechanical Properties

Abstract: Polypropylene (PP) was reinforced with different wood fibers, chemithermomechani-cal (CTMP) aspen and commercial pulps (Tempure and Temalfa-A). Various chemical treatments on the fiber was carried out to improve the bonding at the interface. Fibres coated with Silane coupling agents Silane A-172 and A-174 (with vinyl and methacryloxy functional groups respectively) upon reinforcement showed poor tensile strength. PP filled with Pre-coated fibers containing maleated propylene wax, polymer and polymethylene polyphenyl isocyanate produced higher tensile strength and modulus. The use of dicummyl peroxide and cummine hydro peroxide as initiators during the coating of the fiber was not effective. Polypropylene reinforced with fibers of lower mesh size gave better tensile properties.

Electron scattering cross sections and negative ion states of silane and halide derivatives of silane

Abstract: The interaction of low‐energy electrons with silane and its halogenated derivatives is a fundamental step in many plasma chemical processes. The total scattering cross‐section for electrons in the 0.2–12 eV range are observed to range up to 10−14 cm2. Scattering resonances are assigned to temporary negative ion states on the basis of correlations with analogous inner shell excitation resonances.

Improvement of the photoelectric properties of amorphous SiCx:H by using disilylmethane as a feeding gas

Abstract: Amorphous (a‐) SiCx:H films were deposited in a rf glow discharge of disilylmethane/silane mixtures At optical gaps larger than 2 eV these films are found to have a higher photoconductivity than films prepared in conventional CH4/SiH4 gas mixtures Both types of films are compared with respect to their hydrogen content as well as infrared and effusion spectra

Method for growing silicon single crystal

Abstract: A method for growing silicon single crystal uses as materials, silicon granules prepared by the silane process and having a residual hydrogen concentration of 7.5 wtppm or less, silicon granules prepared by the trichlorosilane process and having a residual chlorine concentration of 15 wtppm or less. In the case where such silicon granules are used, a bursting phenomenon does not occur when the silicon granules are melted. As a result, there is no scattered matter due to the bursting phenomenon, whereby the growth condition of the single crystal is not disturbed.

Novel silicon-modified catalyst Si/HZSM-5, it's preparation, and a process for synthesizing high purity p-dialkyl benzene from monoalkyl benzene by using said catalyst

Abstract: This invention relates to the preparation of a novel Si/HZSM-5 catalyst through vapor phase deposition of Si on the surface of HZSM-5 catalyst which is obtained by ion exchanging ZSM-5 catalyst. The source of deposition Si comes from tetraalkyl ortho-silicate (or tetra-alkoxy silane), Si(OR)4, wherein R represents the alkyl group that contains 1-4 carbon atoms. The silicon deposit will substantially not clog the pores of the catalyst. The present invention is to make use of the modified catalyst in the alkylation or disproportionation reactions in order to enhance the yield of p-dialkylbenzene as an ingredient in the final product of aryl compounds such as toluene or ethylbenzene.