Showing papers on "Substrate (electronics) published in 1968"

Influence of Substrate Temperature on GaAs Epitaxial Deposition Rates

Abstract: The effects of substrate temperature on the GaAs deposition rates were studied for {111}A, {112}A, {113}A, {115}, {100}, {113}B, {112}B, and {111}B substrate orientations An open tube chloride transport system with elemental gallium and arsenic sources was employed This apparatus allowed independent control over the gallium monochloride, arsenic, and hydrogen chloride partial pressures The sensitivity of the deposition rate to substrate orientation is observed to be strongly temperature dependent Experimental evidence is provided which indicates that the deposition rate is kinetically limited in the temperature range from 725° to 800 °C

The resonistor: a frequency selective device utilizing the mechanical resonance of a silicon substrate

Abstract: This communication describes an approach to tuned monolithic circuitry which utilizes the mechanical resonance of a silicon substrate. The proposed device is compatible with monolithic technology and will operate from a few hundred cycles to hundreds of kilocycles. The basic device consists of a silicon cantilever mechanically deflected by electrically induced thermal expansion. Diffused silicon piezo-resistive elements are used to detect stress in the cantilever and provide an electrical output. Maximum stress and electrical output occur when the cantilever is driven at its mechanical resonant frequency.

Electron microscopy at high voltages

Abstract: Experiments have been performed to investigate the useful thickness limits for electron transmission under routine operating conditions for silicon and stainless steel. The criterion adopted for this limit was that thickness at which fringe contrast at faults was destroyed by absorption. The results indicate a roughly linear behaviour of this limit at intermediate voltages, then falling off, but less rapidly than a (v/c)2 law. At 1 Mev foils of silicon ∼9 μ and stainless steel ∼2 μ thick are adequately transparent for observing defects. The ultimate thickness limit is determined by contrast and chromatic aberration. Measurements of the mean absorption parameter versus voltage in silicon showed a non-linear behaviour above about 100 kv. This result is attributed to the effect of many beams which cannot be avoided when using the wedge fringe method at high energies. An application of UHV microscopy to the study of interfaces between epitaxial silicon and its substrate is described.

Thin film coating for sunglasses

Abstract: 1,265,831. Optical filters. EASTMAN KODAK CO. Feb. 27, 1969 [March 4, 1968], No.10481/69. Heading G2J. [Also in Division C7] An optical filter, particularly for use in sunglasses, comprises a gold or copper foil 12 sandwiched between two transparent layers 14, 16, to filter I.R. and U.V. radiation from one side of the filter, and a metal, semi-metal or alloy layer 18, having a complex refractive index whose real part is within a factor of 10 of its imaginary part, to reduce reflection from the other side of the filter. The various layers 12, 14, 16 and 18 are successively deposited on a plastics or glass substrate 20 by vacuum distillation, or in the case of the gold or copper foil by cathodic sputtering, electrolysis or chemical methods. The order of deposition may be reversed, Fig. (not shown) and a protective plastics or glass layer may be provided at the side remote from the substrate, Figs.5 and 6 (not shown). The layers 14, 16 may consist of the oxides of titanium, lead or bismuth or zinc sulphide, and the layer 18 may be constituted by Ni, Fe, Cr, Ti, Al, La, In, Sn, Pb, Ta, W, Co, Mo, Os, Ir, Pt, Yt, Zr, Ni, Zn, Cd, V, Hf, Re, Tl, Si, Ge, As, Sb, or Te or an alloy or any two or more thereof.

Oxide coated semiconductor device having (311) planar face

Abstract: A semiconductor device includes a single crystal substrate comprising a flat surface which has a (311) crystal plane with a tolerance of + OR - 2* with respect to said (311) lattice plane. An insulating film is formed on the flat top surface of the substrate.

Method of producing thin film integrated circuits

Abstract: A METHOD OF PRODUCING THIN FILM INTEGRATED CIRCUITS INCLUDING THIN FILM PASSIVE AND ACTIVE ELEMENTS, WHICH COMPRISES THE STEPS OF DEPOSITING AN ANODIZABLE METAL ON ONE SURFACE OF AN INSULATING SUBSTRATE, ANODIC OXIDIZING THE SURFACE PORTION OF THE DEPOSITED ANODIZABLE METAL INTO ITS OXIDE LAYER OF A DESIRED SHEET RESISTIVITY, DEPOSITING A CONDUCTING METAL OVER THE OXIDE LAYER, ETCHING THE ANODIZABLE METAL, THE OXIDE LAYER AND THE CONDUCTING METAL IN A DESIRED PATTERN TO BOTAIN THIN FILM PASSIVE ELEMENTS SUCH AS A RESISTOR AND A CAPACITOR, AND DEPOSITING A SEMICONDUCTOR MATERIAL TO COVER TWO METAL LAYERS SPACED FROM EACH OTHER EXISTING ON THE OXIDE LAYER TO OBTAIN A THIN FILM ACTIVE ELEMENT.

The Defect Structure of GaP Crystals Grown from Gallium Solutions, Vapor Phase and Liquid Phase Epitaxial Deposition

Abstract: The defect structure of crystals grown from gallium solutions, vapor phase and liquid phase epitaxial deposition is described. Etchants have been used to demarcate emergent dislocations, stacking faults, and p‐n and n‐n+ junctions. Crystals grown from gallium solutions are inhomogeneous with respect to defect structure and contain substantial dislocation‐free regions. Evidence is cited which indicates that some dislocations are introduced during growth whereas others are apparently generated at high stress regions during cooling. It is demonstrated that vapor phase epitaxial deposition on substrates is capable of yielding nearly dislocation‐free crystals containing no stacking faults. The high density of defects observed in crystals grown on substrates is attributed to the heteroepitaxial mode of growth, in particular, the difference in thermal contraction of the growth layer and substrate on cooling from the growth temperature. diodes fabricated by liquid‐phase epitaxy, in contrast to those formed by vapor‐phase epitaxy, do not contain interfacial dislocations at the growth‐substrate interface, i.e., p‐n junction.

Non-destructive readout of ferroelectrics by field effect conductivity modulation

Abstract: CdSe thin film field effect transistors (TFFET) have been deposited by vacuum evaporation on BaTiO3 crystals which can be switched from depletion to enhancement-only operation by switching the ferroelectric substrate. CdSe resistors on BaTiO3 gave two state resistors with resistance ratios of 100 1 obtainable. The efficiency of the devices was nevertheless much less than is theoretically possible. This was due to trapping near the BaTiO3/CdSe interface. A uniform distribution in energy of traps would give the observed dependence of conductance change on initial conductivity.

Electrical and Optical Properties of Vapor‐Grown GaP

Abstract: GaP, both undoped and Se‐ or S‐doped, has been vapor deposited onto the polar 111A (Ga face) and 111B (P or As face) surfaces of GaAs and GaP substrates by means of a PCl3 chemical‐transport method. Hall measurements carried out on the crystals over the temperature range of 77°–500°K and optical spectra taken on as‐grown and zinc‐diffused samples show a pronounced substrate orientation and substrate material effect. Samples grown on GaAs substrates are less uniform than those grown on GaP, and show both a carrier concentration gradient and arsenic contamination. Samples grown on GaP substrates have given electron mobilities as high as 187 cm2/V·sec at room temperature going to 2130 cm2/V·sec at liquidnitrogen temperature. The residual impurity in undoped crystals grown on 111B substrates is shown to be sulfur at a concentration of 2−3×1016 cm−3. Undoped crystals grown on 111A substrates are high‐resistivity p type. Both optical studies and electrical measurements show compensation in the n‐type crystals to be of the order of 10%.

Method for depositing insulating films of silicon nitride and aluminum nitride

Abstract: A SUBSTRATE AND SOURCE, OF SILICON (SI) OR ALUMINUM (AL), ARE POSITIONED WITHIN A NITROGEN-CONTAINING ATMOSPHERE OF LESS THAN 20 MICRONS. RADIO-FREQUENCY ENERGY IS APPLIED ACROSS THE SUBSTRATE AND SOURCE TO GENERATE A PLASMA CONTAINING SOURCE MATERIAL, AND NITROGEN WHICH REACT SO AS TO DEPOSIT A THIN INSULATING FILM, E.G., OF SILICON NITRIDE (SI3N4) OR ALUMINUM NITRIDE (ALN), RESPECTIVELY, ON THE SUBSTRATE SURFACE. PREFERABLY, THE SUBSTRATE IS MAINTAINED IN EXCESS OF 300*C. DURING THE DEPOSITION PROCESS.

Preparation of ZnO Thin‐Film Transducers by Vapor Transport

Abstract: Thin films of ZnO were prepared for transducers and microwave acoustic delay lines. Preliminary results are reported for the latter devices. Vapor transport of ZnO in a sealed system was achieved at a source temperature of 700°C, a source‐substrate distance of 10 cm, a substrate temperature of 570°C, and 2 mm O2. On (0001) sapphire substrates, x‐ray diffraction proved ZnO (0002) planes were oriented parallel to the substrate. Methods were developed for the construction of predominantly longitudinal mode transducers. A one‐way conversion loss of 20 dB at 1.2 GHz was measured.

The Growth and Electrical Characteristics of Epitaxial Layers of Zinc Selenide on p‐Type Germanium

Abstract: The experimental details are given of an evaporation technique for producing epitaxial layers of zinc selenide on 0.1 Ωcm p-type germanium substrates. The degree of crystal order in the deposited layer is presented and the results show that, whilst the (100) orientation readily produces epitaxial layers of zinc selenide, the (110) and (111) orientations are more restricted. The preliminary electrical characteristics of the devices formed on the (100) substrate indicate that, at the higher growth temperatures, an interface layer is formed between the germanium and zinc selenide.

Ellipsometric Investigations of Boron‐Rich Layers on Silicon

Abstract: It is shown that exposure of a silicon substrate to sufficiently high concentrations of diborane results in a surface layer which most likely consists of a silicon‐boron phase. This phase, which is controlled by the diborane concentration and the temperature, gives rise to a prediffused layer of boron in the adjacent substrate. Good control of the phase layer affords good control of the prediffused layer. When the phase layer is removed prior to drive‐in, optimal control is achieved with respect to the final diffused structure.

Method for preparing thin unsupported films of silicon nitride

Abstract: A METHOD IS PROVIDED FOR PRODUCTING EXTREMELY THIN, FREE-STANDING OR UNSUPPORTED FILMS OF SILICON NITRIDE, HAVING THE FORMULA SI3N4. THE METHOD INCLUDES THE INITIAL STEP OF SPUTTERED DEPOSITING ON A MOLYBDENUM SUBSTRATE, A THIN LAYER OF SILICON NITRIDE. THE ASSEMBLY IS THEN LOCATED IN AN OVEN, HEATED TO A TEMPERATURE RANGING FROM 500*C. TO 900*C., AND CHLORINE GAS INTRODUCED INTO THE OVEN. IN THIS MANNER, GASEOUS DISSOLUTION OF THE SUBSTRATE IS EFFECTED, RESULTING IN THE PRODUCTION OF THE FREE-STANDING FILM OF SILICON NITRIDE.

Method of making semiconductor wafer

Abstract: A semiconductor wafer may be made extremely thin, for example, so as to be suitable for use as a solid target of enhanced sensitivity in a vidicon tube, by forming on the marginal portion of one side of a single crystal semiconductor substrate a seeding site which is crystallographically different from the substrate, coating that one side of the substrate with a vapor growth layer of the same conductivity type as the substrate to consist of a polycrystalline region overlying the seeding site and a single crystal region directly overlying the remainder of that side of the substrate, and then removing the semiconductor substrate from the vapor growth layer, as by grinding, to leave a semiconductor wafer of a thickness substantially determined by the thickness of the vapor growth layer and in which cracks that may originate at the edge of wafer, either during grinding or otherwise, are blocked from spreading into the single crystal region at the boundary of the latter with the marginal polycrystalline region. The semiconductor substrate is preferably of a high impurity type so that the concentration of impurity in the single crystal region of the semiconductor wafer produced as aforesaid increases across the thickness of the wafer in the direction toward the surface thereof from which the substrate has been removed.

Compositional Inhomogeneities in GaAs1−xPx Alloy Epitaxial Layers

Abstract: Inhomogeneities in vapor‐grown epitaxial layers of Ga(As, P) alloys on GaAs substrates were studied by the electron microprobe, the divergent‐beam x‐ray method, and x‐ray topography. The epitaxial layers were prepared by growing a graded composition region between the substrate and the final GaAs1−xPx composition. The electron microprobe was used to determine the As/P ratio in the layer by scanning the cleaved edge of the epitaxial layer and substrate. The results showed two types of samples: those with composition steps in the graded composition region and those without these steps. Pseudo‐Kossel patterns for the composition steps as well as for the GaAs substrate and the GaAs1−xPx alloy surface layer are seen in the divergent x‐ray pattern photographs. The sharpness of the pseudo‐Kossel lines indicates that the degree of crystalline perfection decreased with increasing phosphorus content of the epitaxial layer. Lang topographs show that the accommodation for the lattice mismatch between the substrate an...

Field effect transistors for integrated circuits and methods of manufacture

Abstract: P-channel field-effect transistors are described which include a silicon substrate with an N-type epitaxial layer on one face thereof and an N-type subepitaxial diffused region which extends in one direction into a P-type region in the face of the substrate and in the opposite direction into the epitaxial layer to form a junction with a P-type diffused channel region extending partially into the epitaxial layer. These P-channel transistors may constitute a portion of an integrated circuit including a complementary N-channel field effect transistor and/or vertical and surface bipolar NPN and PNP transistors and resistors. Processes are disclosed for forming such transistors wherein a P-type diffusion in an epitaxial layer and an N-type diffused subepitaxial region are further diffused to form a junction therebetween.

Technique for growth of epitaxial compound semiconductor films

Abstract: Epitaxial growth of Group III(a)-V(a) semiconductor compound films is effected in an ultrahigh vacuum by directing collimated molecular beams at the surface of a suitable substrate member preheated to a temperature ranging from 450*-650* C. The described process is a nonequilibrium growth technique which permits the growth of epitaxial films less than 1 micron in thickness at temperatures appreciably below those commonly employed in epitaxy.

Transmissive photocathode and devices utilizing the same

Abstract: Described are transmissive gallium arsenide photocathodes, and optical devices utilizing the same, comprising gallium arsenide epitaxially deposited on a layer of silicon, the gallium arsenide having absorbed into its surface electropositive metal atoms, preferably cesium. In one embodiment of the invention, the gallium arsenide is deposited on a silicon film epitaxially deposited on a transparent sapphire substrate; while in another embodiment, the gallium arsenide is deposited on a thin silicon web having a thickness in the range of about 10 to 25 microns.

Anomalous enhancement of substrate terminal current beyond pinch-off in silicon n-channel MOS transistors and its related phenomena

Abstract: Anomalous enhancement of substrate terminal current is observed in n-channel silicon MOS transistors beyond pinch-off, but not in p-channel devices. This phenomenon is interpreted as the hole current flow caused by the impact ionization of trapped electrons in Si-SiO 2 interface states and of valenced electrons at the pinched-off channel of the silicon surface.

A simple non-destructive method of measuring the thickness of transparent thin films between 10 and 600 nm

Abstract: A simple, non-destructive interferometric method of measuring the thickness of transparent films on a reflecting substrate in the range 0β01 to about 0β6 μ is described. As the incident and reflected rays are directed through the objective of a metallurgical microscope, the region investigated (about 1 mm 2 ) can be examined simultaneously for cleanliness and uniformity. The intensity of the monochromatic reflected light, weakened more or less by interference, is measured by means of a photoresistor located in the ocular tube or the photo tube of the microscope. As examples, the reflection formulas for silicon dioxide and silicon nitride on silicon, and silicon dioxide on germanium, are numerically evaluated and presented in such a form that the thickness can be read directly as a function of the measured reflection. The error lies below 10 nm.

An Evaluation of Materials and Processes for Integrated Microwave Circuits

Abstract: This paper presents an evaluation of materials and processes applicable to the fabrication of hybrid microstrip microwave circuits. Substrate materials evaluated included aluminas, beryllias, quartz, and glass of varying purities and surface finishes. Conductor materials evaluated included silver, copper, gold, and aluminum. Fabrication processes studied included vacuum deposition, sputtering, electroless and electroplating, thick-film screening and firing, and photoetching. Sapphire and high-purity alumina (99.5 percent pure or better) substrates were found superior as substrates for microstrip circuits. Conductor materials and processing methods found best were 1) vacuum deposited chromium-gold thin film which was gold electroplated and photoetched; 2) thick-film silver which was photoetched to delineate the microwave pattern.

Epitaxial Deposition of Germanium onto Semi‐Insulating GaAs

Abstract: Smooth layers of epitaxial Ge have been grown on semi‐insulating using the pyrolysis of . Depositions were made between 600° and 850°C and the range most suitable for obtaining good growth was denned as 650°–750°C. Other factors affecting smoothness were substrate preparation, gas purity, and the total thickness of the deposit. The conductivity type profile of the deposits was determined using a traveling thermal probe on a beveled portion of the deposit, and it showed evidence of outdiffusion of both As and Ga from the substrate into the deposit in addition to As incorporation from the vapor phase. The semi‐insulating properties of the wafers were measured before and after depositions, and it was found that no degradation of the resistivity occurred if the substrates were treated in a solution prior to depositions.