Showing papers on "Chemical vapor deposition published in 1970"

Composite hard metal product

Abstract: A method of chemical vapor deposition (CVD) of a hard layer on a substrate such as cemented tungsten carbide and the product resulting from such method; the method involves a more rapid and more easily controlled CVD of a hard metal such as titanium carbide, by providing an intermediate layer of a refractory interface barrier such as refractory metal on the cemented carbide materials to prevent deleterious interaction between the substrate and the hard metal layer and to obtain a hard wear surface with good composite strength characteristics and bond to the substrate; the product is the resulting composite substrate with the interface metal and the face metal.

by Vapor Deposition

Abstract: The Burean of Mines investigated the formation of boron and boron-carbide coatings by vapor-phase re­ actions. Optimum parameters were determined for hydrogen rednction of boron trichloride and for the formation of boron-carbide coatings on graphite by reaction with the depositing boron. At 1300°C, abont 85 ~'~ of the boron was deposited. Tungsten substrates did not react with the boron deposit; other substrates reacted to various extents. The hydrogen reduction of boron tribromide was brief/u investigated. Boron car­ bide was deposited at 1300°C bU adding methane to the boron trichloride-hydrogen feed gas. The chem­ ical composition of the vapor-deposited boron ca7'­ bide approximated BjC. A method of etching B,C was developed to study its microstructure. When boron was deposited on graphite at 1500°C. veru hard, uniform, strongly adherent coatings of B ,C were formed that might be useful in applications such as rocket nozzles and chemical reaction and processing vessels.

Method for forming adherent titanium carbide coatings on metal or composite substrates

Abstract: DISCLOSED IS A METHOD FOR FORMING ADHERENT COATINGS OF TITANIUM CARBIDE ON METAL OR COMPOSITE SUBSTRATES WHICH INCLUDES THE STEPS OF CARBURIZING THE SURFACE OF THE SUBSTRATE AND REACTING A TITANIUM HALIDE WITH A VOLATILE HYDROCARBON TO FORM AN INTERLAYER COMPRISING A MIXTURE OF TI AND C IN THE MATERIAL OF THE SUBSTRATE, AND THEREAFTER DEPOSITING A COATING OF TIC ON THE INTERLAYER BY CHEMICAL VAPOR DEPOSITION.

Chemical Vapor Deposition of Polycrystalline Al2O3

Abstract: Polycrystalline Al2O3 was chemically vapor-deposited onto sintered Al2O3 substrates by reaction of AlCl3 with (1) H2O, (2) CO:H2, and (3) O2 at 1000° and 1500°C and 0.5 and 5.0 torr. Although the thermodynamics of all these reactions predict the formation of solid Al2O3, the deposition rate of the first reaction was considerably greater than that of the second. The third reaction was so slow that no measurable deposit was formed in 6 h at 1500°C. Formation of dense deposits of α-Al2O3 was favored by increasing temperature and decreasing pressure. Microstructural examination of the dense deposits showed long columnar grains, the largest of which extended through the deposit from the substrate to the surface.

Growth Characteristics of Rutile Film by Chemical Vapor Deposition

Abstract: Thin film rutile has been grown by the chemical vapor deposition reaction of and O2 on silicon and a variety of oxide substrates over a range of temperatures (673°–1320°K) and reactant partial pressures . At high oxygen partial pressures between 990° to 1100°K, the films have been found to contain the rutile modification of almost exclusively. Polycrystalline deposits on silicon, fused quartz, and amorphous silica (thermally grown or chemically vapor deposited) substrates displayed some preferred growth orientation (fiber texture). Epitaxial films were obtained on (001)‐, (110)‐ and (111)‐rutile, , and (0001)‐sapphire substrates at elevated temperatures.

LOW‐TEMPERATURE EPITAXY OF β‐SiC BY REACTIVE DEPOSITION

Abstract: Epitaxial beta SiC film formation on SiC by reactive evaporation or sputtering at low temperature

Method of selective chemical vapor deposition

Abstract: METALS ARE CAUSED TO BE DEPOSITED SELECTIVELY IN THE HYDROGEN REDUCTION OF THEIR COMPOUNDS WHICH ARE EITHER GASEOUS BEARING OR OF ADEQUATE VAPOR PRESSURE. THE PROCESS IS TERMED SELECTIVE-CHEMICAL VAPOR DEPOSITION SINCE THE METAL IS DEPOSITED ONLY ON PREPATTERNED AREAS OF A SUBSTRATE. THE SUBSTRATE IS SUITABLY A GLASS SUCH AS A BOROSILICATE, BOROALUMINO-SILICATE, PHOSPHOALUMINOSILICATE, PHOSPHOSILICATE OR SODA-LIME GLASS. THE SELECTIVECHEMICAL VAPOR DEPOSTION PROCESS OCCURS WHEN TWO SURFACES WITH DIFFERENT CHEMICAL REACTIVITIES ARE EXPOSED TO THE CHEMICAL VAPOR DEPOSITION ENVIRONMENT. THE PREPATTERNED AREAS PROVIDE ONE OF THESE SURFACES, SUCH AREAS COMPRISING A NUCLEATION LAYER OF A MATERIAL SUCH AS CHROMIUM, TUNGSTEN, MOLYBDENUM, COPPER, ALUMINUM, SILICON, SILICON DIOXIDE, ALUMINUM OXIDE, SILICON NITTRIDE AND THE LIKE, OR A COMPOSITE LAYER OF CHROMIUM-COPPER, CHROMIUM-COPPER CHROMIUM AND THE LIKE. THE OTHER SURFACE IS PROVIDED BY THE REMAINDER OF THE SURFACE OF THE EXPOSED SUBSTRATE. THE SURFACE PROVIDED BY THE PREPATTERNED AREA ACTS AS A METAL MUCLEATION SITE WHILE THE GLASS SURFACE IS CHEMICALLY ERODED (ABLATED) AND THE METAL DOES NOT NUCLEATE THEREON. AN EXAMPLE OF THE PROCESS IS THE CHEMICAL REDUCTION OF COPPER HEXAFLUOROACETYLACETONATE BY HYDROGEN IN THE PRESENCE OF HYDROGEN FLUORIDE OR SULFUR HEXAFLUORIDE IN A REACTION CHAMBER. THE CHAMBER CONTAINS A SUBSTRATE HAVING A PATTERNED NUCLEATING LAYER THEREON ON WHICH THE REDUCED COPPER DEPOSITS WHILE THE SUBSTRATE IS ABLATED BY THE FLUORIDE. THE DEPOSITION REACTIONS AND SIMULTANEOUS ABLATION REACTION, ACTING IN CLOSE PROXIMITY, ARE ESSENTIAL ELEMENTS OF THE INVENTIVES PROCESS.

Chemical Vapor Deposition of Silicate Glasses for Use with Silicon Devices II . Film Properties

Abstract: Chemical, dielectric, thermal, and optical properties of glass films synthesized by chemical vapor reactions from the hydrides are discussed. The binary borosilicate glasses deposited at low temperature from silane, diborane, and oxygen require a thermal densification to approach bulk glass properties. The rate of densification in the temperature range of 770°–800°C is very rapid but water vapor has an accelerating influence, allowing densification at reasonable rates at temperatures as low as 450°C. The thermal expansion match with silicon was sufficiently close to allow the crack‐free coating of wafers with 12µ of glass. Borosilicate films of 5µ thickness on silicon withstood severe thermal shock, temperature cycling, moisture penetration, and corrosion resistance tests. Densified borosilicate of typical compositions had a dielectric constant of 3.8–4.1 and a dissipation factor at 103 Hz of 0.10–0.15. The d‐c dielectric field strength sustained by MIS capacitors made from 1µ thick densified films measured before and after a 1‐yr exposure to room air, was . The properties of vapor‐deposited phosphosilicate glasses and of glasses containing the oxides of aluminum and zinc are briefly described.

Cadmium/Sulfur Isothermal Source for CdS Deposition

Abstract: This paper describes the theory and construction of apparatus for the vapor deposition of highly resistive, highly oriented, piezoelectrically active cadmium sulfide films from the constituent elements. The cadmium and sulfur are evaporated from a double coaxial isothermal source, the composition of the vapor beam being determined predominantly by the area of an orifice in each source. The source operates at 420°C, and condensation rates of 300 A/sec are readily obtained. The deposition rate may be varied over a wide range (say, 15 to 1) with little resultant change in resistivity. Films were deposited on fused quartz to serve as electromechanical transducers. A shear mode coupling constant kt of 0.12 was measured. The longitudinal mode signal level was 46 dB below that of the shear mode at the upper 3 dB shear mode frequency. A longitudinal mode kt of 0.12 has been obtained with a shear mode suppression of 60 dB.

Diamond tool and method of making the same

Abstract: A grinding and cutting tool comprised of diamond particles bonded to a support base member by the process of vapor deposition to form a metal lattice matrix chemically bonded to a surface of the diamond particles and metallurgically bonded to the support base member and the diamonds bonded to each other by inosculation, the reactions greatly enhancing the strength of the bonds. A novel method of vapor deposition, controlled by electrical charges and by said means to impart kinetic energy to the ions of the vapor of sufficient velocity to cause penetration of said ions into the molecular structure of the support base causing a metallurgical reaction and into the molecular structure of the diamond surfaces causing a chemical reaction. In addition, by inducing a secondary electrical field, divergence of said ions can be controlled to cause said ions to be deposited in a predetermined pattern.

Thin film electronic components on flexible metal substrates

Abstract: This disclosure is concerned with thin film field effect transistor (FET) formed on flexible metal substrates by vapor deposition techniques. The FET is electrically insulated from the metal substrate by an electrically insulating varnish.

The grain size dependence of the yield, flow and fracture stress of commercial purity silver

Abstract: Heavily cold-rolled sheet material of 99.9 pct purity Ag has been recrystallized at varying temperatures to give average grain diameters,l, in the range between 1 and 60 μ. For this material, the yield stress, flow stress at several strain values, and fracture stress follow the Hall-Petch relation: $$\sigma _\varepsilon = \sigma o_\varepsilon + k_\varepsilon l^{ - 1/2} $$ whereσ e is the flow stress at a particular value of strain, e, ands o e andk e are the experimental constants appropriate to a particular strain value. The range in grain size obtained for this material was sufficiently large to determine that silver can be appreciably strengthened by grain size refinement and that several other relations previously suggested to relate the stress and grain size could be discounted. The finest grain sizes were measured from replicas of etched specimens as viewed with the electron microscope. It is proposed that this type of grain size strengthening may be responsible for the exceptional strength which occurs in certain films of silver fabricated by vapor deposition techniques.

Vapor Deposition by Liquid Phase Sputtering

Abstract: Liquid binary alloy targets have been sputtered at ion densities of up to 100 W/cm2 providing deposition rates in excess of 10 mils/h in a combined sputtering-evaporation mode. At high power densities a serf-sputtering mode has been demonstrated which allows deposition from 10−7 to 10−2 Torr. Comparison of sputtered deposit compositions of Pb-24 In, Fe-30 V and Fe-32 Ni with theoretical molar ratios predicted on the basis of thermal vaporization shows that alloy fractionation is substantially reduced. The composition of deposits from solid or liquid Pb-24 In targets had nearly the same Pb/In ratio, 5.8 (target ratio = 1.75) although the predicted ratio for thermalized vapor was 1300. For Fe-30 V liquid targets where less than 0.5% vanadium is predicted from thermal vaporization alone, a sputtered deposit containing 10.3% vanadium was found, suggesting that the approximate sputtering/evaporation ratio is 0.3. Liquid phase targets of Fe-32 Ni alloy had average molar ratios of Fe/Ni close to 3 (target ratio ...

Insulated gate field-effect device and method of fabrication

Abstract: An insulated gate field-effect transistor is fabricated to include an improved insulation layer comprising a film of silicon dioxide covered with a film of silicon nitride. The method of fabrication includes the thermal oxidation of a semiconductor silicon surface in a ''''reducing'''' atomsphere. The use of hydrogen as a carrier gas for oxygen provides a thermally grown, pinholefree oxide film having improved stability under conditions of heat cycling and electrical bias. The process permits a control of oxidation rate by adjusting the oxygen content of the gaseous mixture, rather than by the control of temperature. Best device characteristics are obtained by proceeding immediately with the vapor deposition of silicon nitride on the oxide, as a substantially continuous operation in the same reactor.

Magnetic Properties of GdIG Films Grown by Chemical Vapor Deposition

Abstract: GdIG films with thicknesses from 0.3 μ to 3.0 μ have been grown epitaxially on the (100), (110), (111), and (320) faces of yttrium aluminum garnet substrates by chemical vapor deposition in a reactor consisting of two concentric tubes. The influence of substrate temperature, transport rates of iron and gadolinium chloride, partial pressures of oxygen, water vapor, and HCl, and substrate position on film growth have been determined. It is shown that diffusion between the film and substrate causes a variation in the compensation temperature through the film volume. This results in an asymmetry in the coercive force about the compensation temperature and anomolous behavior in the Faraday‐effect hysteresis loops. These observations are discussed in terms of several possible models.

Silicon Nitride Prepared by the SiH 4 -NH 3 Reaction with Catalysts

Abstract: The application of catalysts to chemical vapor deposition process to activate reactive species is shown effective in improving electrical properties of Si-Si3-N4 systems. NFB of the Si-Si3-N4 system prepared by the catalytic method is about one tenth of NFB of those prepared by the conventional method. The catalysts of NiO and Pt are applied to the ammonia and silane respectively. The catalysis seems to be effective to reduce the deposition temperature by about 100°C. The density of the interface states is about 1×1011 cm-2 and the peak energy levels of donor and acceptor states are 0.43 eV and -0.47 eV respectively. Infection type hysteresis loops are always observed in the inversion region of both p- and n-type samples at a low temperature. The hysteresis is proportional to the film thickness and is independent of the preliminary treatments.

Low-temperature vapor deposits of thick film coatings

Abstract: The application of metal coatings through vapor deposition is improved by activating the coating with an abrasivelike action during the deposition process. The resultant coatings have increased smoothness, ductility and high-density (low-porosity).

SiO 2 /Si 3 N 4 passivation of high-power rectifiers

Abstract: High-power mesa-type rectifiers were passivated with successive layers of SiO 2 and Si 3 N 4 by a low-temperature chemical vapor deposition technique. Reverse I-V characteristics, high-temperature yield, ancl blocking life test results are compared with values obtained with a polyimide coating. The high-temperature performance of the oxide-nitride passivated unit is found to be superior to the polyimide coated units. A strong correlation between the high-temperature leakage current and thermal stability of the device is noted.

Vapor Deposition and Etching Open Tube Kinetics under Diffusion Controlled Conditions

Abstract: A quantitative method for treating chemical deposition and etching open tube processes is described. The method is based on the gas dynamic theory of boundary layer and on the similarity of mass‐ and heat‐transfer phenomena. For the conditions , the equation for the rate of the process is This equation is applied for the calculation of the rate of Ge and Si crystals deposition and etching. A good agreement of calculated and experimental values is obtained.

Structure of Silicon Films Deposited on Oxidized Silicon Wafers

Abstract: Silane for polycrystalline films deposition on oxidized silicon wafers, noting substrate temperature effects on preferred orientation of deposits

Nitrogen nucleation process for the chemical vapor deposition of polycrystalline silicon from sici4

Abstract: A PROCESS IS DISCLOSED HEREIN FOR THE USE OF NITROGEN IN A NUCLEATION PROCESS FOR THE CHEMICAL VAPOR DEPOSITION OF POLYCRYSTALLINE SILICON FROM SICL4. AFTER ESTABLISHING THE DESIRED FURNACE TEMPERATURE AT A SINGLE TEMPERATURE LYING WITHIN THE RANGE OF 900*C. TO 1200*C., THE SYSTEM IS PURGED WITH NITROGEN AND HYDROGEN. AFTER THE SYSTEM HAS BEEN PURGED, THE NITROGEN FLOW IS STOPPED AND THE SICL4 FLOW IS STARTED SIMULTANEOUSLY. THE OVERLAP OF NITROGEN AND SICL4 WITHIN THE SYSTEM CAUSES NUCLEATION FROM WHICH A VERY FINEGRAIN LAYER OF POLYCRYSTALLINE SILICON IS GROWN.

Boron and boron carbide coatings by vapor deposition.

Abstract: The Bureau of Mines investigated the formation of boron and boron-carbide coatings by vaporphase reactions. Optimum parameters were determined for hydrogen reduction of boron trichloride and for the formation of boron-carbide coatings on graphite by reaction with the deposited boron. At 1300°C, about 85 pct of the boron was deposited. Tungsten substrates did not react with the boron deposit; other substrates reacted to various extents. The hydrogen reduction of boron tribromide was briefly investigated. Boron carbide was deposited at 1300°C by adding methane to the boron trichloride-hydrogen feed gas. The chemical composition of the vapor-deposited boron carbide approximated B4C. A method of etching B4C was developed to study its microstructure. When boron was deposited on graphite at 1500°C, very hard, uniform, strongly adherent coatings of B4C were formed that might be useful in applications such as rocket nozzles and chemical reaction and processing vessels.

Vapor deposition of rhenium and rhenium-tungsten alloy coatings

Abstract: A PROCESS FOR COATING A SUBSTRATE WITH RHENIUM. A MIXTURE OF GASEOUS HYDROGEN AND A RHENIUM OXYCHLORIDE VAPORIZED IN AN INERT GAS IS PASSED OVER THE SUBSTRATE, WHICH IS HEATED TOA TEMPERATURE EFFECTING REDUCTION OF THE OXYCHLORIDE AND DEPOSITION OF RHENIUM METAL ON THE SUBSTRATE. A RHENIUM-TUNGSTEN ALLOY COATING CAN BE DEPOSITED BY INCORPORATING TUNGSTEN HEXAFLUORIDE IN THE GAS MIXTURE PASSED OVER THE SUBSTRATE.

Vapor Deposited Titanium Dioxide Thin Films: Some Properties as a Function of Crystalline Phase.

Abstract: : Thin films of TiO2 are grown in a low temperature (150C) vapor deposition process by hydrolyzing tetraisopropyl titanate at the substrate. These films can be made uniform over a 1-1/4 in substrate to within 100 A and are found to be amorphous in the 'as grown' condition. Films in the amorphous state have an index of refraction of 2.0 and can be etched easily (50 A/sec) in 0.5% HF. Annealing in air at 350C converts the film to the anatase tetragonal crystalline form and at 700C to a mixture of anatase and rutile. Both forms are quite etch resistant, but the anatase can be etched by HF and warm H2SO4. At 1000C, the film is completely rutile with an index of refraction of 2.5. This form is extremely etch resistant even in 120C H2SO4 (1000 A/hour). The conversion from amorphous to rutile is accompanied by a thickness decrease of 36%. (Author)

Composition Gradients in Ni–Fe Alloy Films Produced by Vapor Deposition from a Tungsten Boat

Abstract: When an alloy film is produced by evaporation from a limited volume of material in a tungsten boat, differences in the vapor pressures of the constituents can produce different compositions through the thickness of the film. These composition changes can affect magnetic properties; e.g., it has been suggested that magnetization gradients produce anomalies in spin wave spectra. We have measured the variation of composition through the thickness of Ni–Fe films by moving a long substrate past a collimated source during deposition from a boat. It is observed that for a wide range of deposition temperatures and integrated thickness the results nearly coincide if all of the data are plotted as a function of normalized fractional thickness. For starting material of 80.89% Ni, evaporated to completion, the initial composition is 74% Ni and rises linearly to 81% Ni at 0.8 fractional thickness. A steeply rising exponential region follows. The origin of these regions will be discussed.

Thickness Monitor for Transparent Thin Film Deposition

Abstract: A technique is described for monitoring the thickness of transparent thin films growing on heated polished substrates (as in chemical vapor deposition). Thermal energy, radiated by a substrate and transmitted by a growing film, undergoes optical interference as a result of multiple reflections between the substrate‐film and film‐ambient interfaces. A narrow bandpass detector is used to measure the transmitted intensity and film thickness is correlated with the maxima and minima of the detector output. Using a 1P21 photomultiplier tube and a 6000 A interference filter (90 A half‐width) this technique has been applied for substrate temperatures as low as 800°C and thickness in the range of 1000–6000 A with an accuracy of ± 100 A. A special comparison technique is described which operates by sampling, storing, and subtracting signal intensities obtained from two substrates. Using this technique it is possible to terminate deposition of the outer film of a duplex combination (500 A of Al2O3 on SiO2, for examp...

Silicon-silicon dioxide interface of predetermined space charge polarity

Abstract: In the fabrication of a semiconductor device having a silicon-silicon dioxide interface, the polarity of the space charge region associated with the interface is predetermined by a method which begins with the step of pretreating the silicon surface with a selected reagent capable of inducing the desired space charge polarity. For example, a pretreatment with chromic acid induces a negative space charge region, whereas a pretreatment with nitric acid induces a positive charge. The interface is then formed by vapor deposition of a silicon dioxide layer on the silicon surface. The pretreatment has been found capable of inducing a predetermined charge when the interface is provided by vapor deposition, but is wholly ineffective when the interface is provided by thermal oxidation. It is well known that thermal oxidation of a silicon surface inherently produces an interface having a positive space charge region.