Showing papers on "Substrate (electronics) published in 1969"

Anisotropic Etching of Silicon

Abstract: A ternary liquid etchant solution for silicon, consisting of hydrazine, iso‐2‐propyl alcohol (IPA), and water has been studied in some detail. In common with other anisotropic etchants reported in the literature, marked dependence of dissolution rate on the crystal orientation of the etched surface has been observed with a low rate of attack on (111) planes. In contrast to other formulations, this etch attacks neither silicon dioxide nor aluminium vacuum‐deposited films, either of which may be used as a very convenient in‐contact masking medium for the engraving of intricate shapes on an appropriately oriented silicon substrate. The experimental study indicates that the etch velocity is a maximum for (211) planes, which accounts for the rounding of convex corners frequently observed when engraving regular shapes in silicon with anisotropic etches. The optimum etch solution is an equimolar mixture of NH2 and H2O.

Measurement techniques in microstrip

Abstract: A novel technique has been developed for measurement of dispersion and wavelength in microstrip transmission line laid down on an Al2O3 substrate. The frequency range so far investigated has been 4-12GHz, although the method could be satisfactorily used at far higher frequencies. The measurement accuracy is better than within 1%. Techniques for producing well matched transitions to any thickness substrate have also been established.

Isolation of junction devices in GaAs using proton bombardment

Abstract: Proton bombardment has been used to convert both p- and n-type GaAs into high resistivity material. It will be shown that this technique is useful for isolating junction devices and fabricating arrays. The average carrier concentration in the bombarded layer is less than 1011/cm3, and the layer thickness is about one micron for every 100 keV of proton energy. These layers are apparently unaffected by a 16 hr anneal at 300°, and only slightly affected at 400°. Using this technique, we have isolated islands of n-type GaAs on a semi-insulating substrate, separated p-n junctions on an n-type substrate, and suppressed edge breakdown in Au-GaAs Schottky barrier diodes.

Amorphous versus Crystalline GeTe Films. I. Growth and Structural Behavior

Abstract: As a part of our structural, optical, and electrical studies of amorphous versus crystalline GeTe films, this paper (Part I) reports on the growth and structural properties of the thin‐film polymorphs (amorphous, rhombohedral, and NaCl) of GeTe. When deposited above ∼130°C, the GeTe films are polycrystalline. Epitaxial or partially oriented growth of the rhombohedral phase is obtained on NaCl and mica at deposition temperatures ∼250°C. An electric field ∼4000 V/cm applied laterally on the substrate during deposition lowers the epitaxial temperature. At temperatures above 250°C, the high‐temperature NaCl structure grows epitaxially. Below a deposition temperature of ∼130°C, the films are amorphous. The amorphous phase transforms very rapidly via random nucleation centers to the crystalline phase at a well‐defined temperature of 145±3°C accompanied by the release of heat ∼1±0.2 kcal/mole (∼½kTm, where k is Boltzmann's constant and Tm is the melting point of GeTe). The transformation temperature increases li...

Electrical conduction in ultra thin metal films I. Theoretical

Abstract: A theory is developed to account for the transport of charge in ultra thin, aggregated metal films, using quantum mechanical electron tunnelling, and thermionic emission theories. The current density in the film is expressed as a direct function of the structure of the film, the electrical properties of the substrate, the applied voltage and the temperature. It is shown that for a typical aggregated metal film conduction is by electron tunnelling, and that the tunnelling path is through the substrate. The trap hopping model of conduction on an active substrate is re-examined and limits are established for each of the mechanisms. It is shown that the activation energy associated with conduction in very thin films is due to the interaction of Coulombic fields surrounding small, discrete, metal particles. Four types of film structures are analysed, depending on whether the particles and the gaps between them are large or small. For small particles and small gaps the basic mechanism of conduction is an activated quantum mechanical tunnelling; for large gaps conduction in the substrate dominates, whereas for large particles with small gaps a simple, unactivated, tunnelling process is dominant.

Formation Processes of Vacuum-Deposited Indium Films and Thermodynamical Properties of Submicroscopic Particles Observed by In Situ Electron Microscopy

Abstract: The formation of vacuum-deposited In thin films was studied by in situ electron microscopy. The dependence of melting point and crystallization temperature on particle size was measured. A preferred orientation was found to develop at a given crystallite size depending on the substrate temperature and on the ratio of impinging oxygen molecules to film atoms (K factor).

Mechanical Properties of Metal Oxide Films

Abstract: A brief review is given of mechanical property measurements on oxide films. This review is followed by a detailed discussion of the mechanical and fracture properties of anodic aluminum oxide films as observed in the author's laboratory. Extensive measurement of Young's modulus, ,and fracture strain, , for separated films 3000Aa thick is reported as a function of environmental water vapor pressure. The fracture of these unsupported films is shown to occur by a brittle mechanism. Mechanical properties of adhering aluminum oxide films are given as a function of their thickness. These oxides were observed to fracture either at slip steps, or at right angles to the tensile axis in a regularly spaced fashion. A theory of adhering oxide fracture is discussed which accounts well for the observations. An equation which describes the spacing of regular oxide fracture cracks as a function of substrate strain e is given in the form , where () are the initial conditions for regular fracture, is the oxide thickness, and is a constant.

Combination film deposited switch unit and integrated circuits

Abstract: A semiconductor substrate, like a silicon chip having various doped regions forming circuit elements, has semiconductor switchforming units deposited thereon. The integrated circuit semiconductor switch combination desirably may form a memory matrix where the substrate has spaced parallel, doped conductorforming regions of a given conductivity type extending in spaced, generally parallel relation. Spaced parallel bands of conductive material are deposited on an insulating film on a face of the substrate and extend generally transversely of said spaced parallel conductor-forming regions of the substrate. A two terminal memory switch device is formed on the substrate adjacent each active cross-over point of the transversely extending conductors, each memory switch device including a deposited film of semiconductor memory material having spaced portions electrically coupled between the associated cross-over point.

RF sputtered strontium titanate films

Abstract: Two deposition parameters are important in rf sputtering of SrTiO3 films: the oxygen-argon content ratio, and the substrate temperature. More than 1% oxygen is needed to produce insulating films; the exact percentage required depends on system cleanliness. Both dielectric ccnstant and crystallite size increase with increasing substrate temperature. Films of 2400 A deposited at 500°C on gold have a dielectric constant of 200. The dc conductivity closely follows the Poole-Frenkel model. Two dielectric loss peaks are believed to be caused in part by an oxygen deficient region near one electrode. The variation in the dielectric constant K with electric field is similar to that observed in bulk material.

Igfet comprising n-type silicon substrate, silicon oxide gate insulator and p-type polycrystalline silicon gate electrode

Abstract: Insulated Gate Field Effect Transistor employing a polycrystalline semiconductor surface layer, one strip of which serves as the gate electrode of the IGFET, and another strip of which may serve as a resistor. The semiconductor surface layer is employed as a mask for the diffusion of the source and drain regions, thereby insuring automatic alignment between the gate electrode and the source and drain regions.

Preparation and Structural Properties of GaN Thin Films

Abstract: We describe here a method that is capable of producing GaN thin films on either heated or unheated substrates. This method makes use of a remote gaseous discharge to dissociate molecular N2 into atomic N, which is then able to combine with Ga being evaporated onto the substrate. Using glancing angle x-ray diffraction and reflection electron diffraction techniques, we have studied structural properties of GaN thin films grown with this system on substrates of fused quartz, and oriented GaAs and Al2O3. At low substrate temperatures, smooth, transparent polycrystalline films result, while at temperatures above 550° C we have obtained epitaxial GaN on both {111} faces of GaAs and on {0001} faces of Al2O3. The epitaxial films show a simple orientational relationship to these substrates.

Vacuum Deposition by High-Energy Laser with Emphasis on Barium Titanate Films

Abstract: A laser beam capable of energy outputs up to 500 Joule was directed through a glass window into a vacuum system onto fine grain powder of Cr, W, Ti, C, Sb2S3, ZnS, SrTiO3, and BaTiO3. A neodymium-doped glass laser of 1.06-μ wavelength was mostly used without Q spoiling. Sometimes the beam was focused. Films up to 2000 A were achieved on glass with one laser burst only, which corresponds to deposition rates of up to 106 A/sec. The substrate was positioned between the vapor source and laser so that the laser beam passed through it, and therefore, also served as a shield. Electron micrographs were taken. From electron transmission diffraction patterns it appeared as if BaTiO3 had not been decomposed. In order to evaluate electrical properties of the films, platinum-rhodium films were sputtered or “laser-deposited” onto glass slides to serve as base electrode. Then a barium titanate film was evaporated with a laser. On top of this, an array of thin aluminum dots were evaporated through a mask, so that it was ...

Growth and Characterization of Spinel Single Crystals for Substrate Use in Integrated Electronics

Abstract: An extensive study has been made on the growth and characterization of single‐crystal magnesium aluminate spinel. This material has received attention as a superior substrate for epitaxial silicon‐integrated electronic devices. Large spinel single crystals within the compositional range MgO:Al2O3–MgO:3Al2O3, have been successfully grown by flame fusion using a modern three‐tube post‐mix‐type Verneuil burner. Substrate wafers of (111), (100), and (110) orientations were prepared for silicon epitaxy. Surface preparation of the substrates was studied, including mechanical polishing, hydrogen annealing, and chemical etching. The composition, lattice parameter, crystalline perfection, mechanical hardness, thermal stability, and dielectric properties of the spinel single crystals have been characterized by various techniques in an effort to obtain a basic understanding for substrate use of this material system. Some trends in the dependence of these properties on composition were observed. In particular, the th...

Process for forming a film on the surface of a substrate by a gas phase

Abstract: A process for forming a film on the surface of a substrate by a gas phase method in the presence of a catalyst used in the solid state electronics at a predetermined distance from the surface of the substrate on which the film is to be formed and a process for forming a silicon oxide or silicon nitride in the presence of a catalyst selected from the group comprising platinum and the like.

Method for epitactic precipitation of silicon at low temperatures

Abstract: A method for producing highly pure, monocrystalline silicon layers, with or without dopant additions, upon a wafer shaped substrate body, which comprises thermal dissociating a gaseous silane compound, and by precipitating silicon upon a heated substrate body located in a reaction chamber. The crystalline structure of the silicon body is exposed e.g. by etching and its surface is flooded by the reaction gas. The silane compound is a dihalogen silane of formula SiH2X2, wherein X is chlorine, bromine, or iodine. The thermal dissociation is effected by heating the substrate body at low temperatures, preferably within a temperature range between 600* and 1,000* C.

Deposited silicon diffusion sources

Abstract: Non-single crystal semiconductor material formed on a semiconductor substrate and separated from all but a portion of the substrate by an intervening insulation layer contains at least one dopant and preferably two dopants of opposite conductivity type. Heating the substrate, together with the overlying insulation and non-single crystal semiconductor layers, drives the dopants contained in the non-single crystal semiconductor material into the underlying semiconductor substrate in such a manner as to form diodes or transistors.

Solution grown SiC p-n junctions

Abstract: Epitaxial growth of silicon carbide on α-SiC substrates has been carried out at 1650°C in carbon-saturated silicon solutions. The quality of growth is found to be strongly dependent on the inclination of the substrate in the melt, an angle of 40° to the horizontal resulting in the growth of uniform layers of the same polytype as the substrate. With this technique p-n junctions have been prepared using nitrogen, aluminium and boron impurities, and their diode and electroluminescent properties examined.

Epitaxial Thin Films of ZnO on CdS and Sapphire

Abstract: The technique for obtaining polycrystalline thin films of ZnO by sputtering of the compound has been perfected so that epitaxial films can be obtained on sapphire and CdS Dependence of the crystalline perfection of the films on substrate temperature, deposition rate, and substrate polish has been studied in detail Substrate temperatures from 100 ° to 500 °C and deposition rates from 1 to 100 A/min were studied Film structure was evaluated by x-ray diffraction and reflection electron diffraction Electrical and optical measurements were made to determine the resistivity, Hall mobility, optical absorption edge, and refractive index of films It was found that these properties of the films were very similar to bulk crystal data except for the Hall mobility which was lower by almost two orders of magnitude The poor mobility is attributed to scattering by defects introduced during the high-energy sputtering process

Electrical and Optical Properties of n‐Type Si‐Compensated GaAs Prepared by Liquid‐Phase Epitaxy

Abstract: The radiative processes in Si‐compensated, n‐type GaAs prepared by liquid‐phase epitaxy have been studied by photoluminescence between 300° and 4.2°K. The data are consistent with the previous hypothesis of the formation under certain growth conditions of two types of acceptor levels by Si in GaAs (in addition to the shallow donor level) with ionization energies of ∼0.03 and ∼0.1 eV. Three basic radiative processes dominate at various temperatures: (a) Band‐to‐band recombination at 300°K, (b) conduction band (or possibly conduction‐band tail states) to shallow acceptor transitions at 4.2°K, and (c) conduction band to the deeper acceptor transitions at 77°K. The half‐width of the third emission band and its peak position depends on the Si and free‐carrier densities. The degree of compensation of these materials is a function of the substrate orientation. Of the three planes investigated, (100), (111)‐Ga, and (111)‐As, growth on the (111)‐As face results in the lowest degree of compensation. The present study shows that n‐type material with mobilities in excess of 1000 cm2/V·sec and electron concentration in the 2–4×1018 cm−3 range can be prepared by growth at 1060°C with the advantage over Te‐ or Se‐doped GaAs that the formation of precipitates of Ga2Se3 or Ga2Te3 is eliminated. Such precipitates were previously shown to seriously degrade the radiative efficiency and hence the performance of injection lasers and spontaneous emitters.

Electrical Conduction in Ultra Thin Metal Films. II. Experimental

Abstract: A number of thin aggregated metal films on glass substrates are analysed in terms of the model proposed earlier (Hill 1969). It is shown that the model is consistent, and that the conductivity of a thin metal film forming an island structure can be defined in terms of the island size and spacing, and of the properties of the substrate and the film material. The potential barrier heights for electron tunnelling between particles of gold, particles of platinum, and particles of silver through soda and barium aluminosilicate glass have been determined. It is shown that the bias effect in thin metal films (Hill 1964a) can only be observed with metals of work function close to that of the substrate material and when the substrate contains free alkali ions.

Method of forming silicon oxide coatings in an electric discharge

Abstract: This is a method of depositing a coherent solid layer of an oxide of silicon deposited upon a surface of a substrate by establishing a glow discharge adjacent to said surface in an atmosphere containing a gaseous compound of the element or elements comprising the material.

Structure and Performance of Hydrophobic Gas Electrodes

Abstract: HYDROPHOBIC gas electrodes can demonstrate high performance even at ambient temperatures1. These electrodes are made by mixing a finely divided catalyst, such as Pt black, with polytetrafluoroethylene (PTFE) dispersion and applying the mixture to a porous conducting substrate, such as a metal screen. The electrodes are dried and cured at 300° C for 1 h.

Method of forming thin insulating films particularly for piezoelectric transducers

Abstract: A film of an insulating compound is formed by evaporating constituent elements from sources screened by a baffle from the substrate while maintaining the substrate at a temperature at which individual elements will not deposit. II-VI, III-V and other compounds are so formed including compounds such as oxides. The film is stoichiometric and highly oriented when formed on a suitable substrate. Metal oxides, including those of zinc, silicon, magnesium, beryllium, titanium, zirconium and binary oxides such as lithium-gallium oxide, are formed with a low substrate temperature (at least -75* C.). Piezoelectric transducers, as well as other devices, may be so formed in highly oriented films of which zinc oxide offers the highest known electromechanical coupling coefficient.

Thin-film silicon: Preparation, properties, and device applications

Abstract: This paper will review the properties of thin silicon films deposited on sapphire (SOS) and magnesium aluminate spinel by the pyrolysis of silane in the temperature range 900-1200°C. Variations of carrier mobility, free-carrier concentration, minority carrier lifetime, crystalline perfection, and surface quality will be discussed as a function of substrate crystal and growth parameters. MOS transistors exhibiting field-effect mobility close to that obtained with bulk silicon have been fabricated and a complementary MOS transistor memory cell has been constructed with a WRITE-READ delay of 6 ns. The standby power for the cell is typically 10 µW. Other CMOS circuits display a pair-delay of 1.5-2.0 ns. AIl-epitaxial bipolar transistors with a current gain of 5 and f T of 350 MHz have been made in which all layers are sequentially deposited during one high-temperature operation. Recent improvements in bipolar fabrication techniques have lead to current gains as high as 25 at 10 mA.

Effect of Deposition Parameters on the Crystallinity of Evaporated Germanium Films

Abstract: The crystallinity of Ge films deposited on (111) Ge substrates in vacuum ambients <10−8 Torr has been investigated as a function of deposition rate, substrate temperature, thermal treatment of substrates, and background oxygen pressure. Polycrystalline and epitaxial films were obtained at temperatures up to 200° lower than reported by previous investigations, and thermal annealing of substrates at 600°C prior to deposition resulted in a minimum epitaxial temperature of 100°C. Oxygen ambients as low as 5×10−9 Torr have been found to impede crystal growth and increase epitaxial temperatures by 50°–75°C.

Process for manufacturing face-down-bonded semiconductor device

Abstract: A FACE-DOWN-BONDED SEMICONDUCTOR DEVICE IS DISCLOSED IN WHICH THE ELECTRODES OF A SEMICONDUCTOR ELEMENT AND OF THE SUBSTRATE CARRYING THAT ELEMENT BY FACE-DOWNBONDING HAS A SURFACE FORMED OF A FIRST METAL WHICH READILY FORMS AN ALLOY WITH A SECOD METAL, THAT ALLOY HAVING THE CHARACTERISTIC THAT ITS MELTING POINT IS HIGHER THAN THAT OF THE SECOND METAL.

Some Magnetic and Structural Properties of Epitaxial Garnet Films Prepared by rf Sputtering

Abstract: Epitaxial garnet films have been prepared by rf sputtering from a polycrystalline gadolinium iron garnet target onto single‐crystal substrates of YAG. Epitaxy is achieved on all orientations of the substrate, either in situ when depositing at ≥500°C, or during post‐deposition crystallization of amorphous or partially crystallized films deposited at <500°C. The compensation temperature in epitaxial films depends strongly on the deposition temperature. The lowest compensation temperatures are found in films prepared at the highest deposition temperatures. Flims prepared on glass substrates at elevated deposition temperatures are iron deficient and crystallize in at least two phases, Gd3Fe5O12 and GdFeO3. The iron deficiency in these films is assumed to be caused by a variation with temperature in the net cation sticking coefficients. No GdFeO3 phase is found in epitaxial films prepared at the same elevated deposition temperatures, although these films should also be iron deficient. It is believed that they ...

Nucleation and Surface Conditions

Abstract: The nucleation of Ag and Au on alkali halides is discussed excluding the influence of adsorbed gas layers. In particular, the problems of nucleation density and of the orientation of nuclei with respect to the substrate crystal are treated. The influence of defects in the surface on nucleation density is discussed in detail. Some principal aspects necessary for a theoretical treatment are pointed out. A review of the problem of the orientation of nuclei is given. An explanation of some recent results, the possible influence of electrical double layers (Debye-Frenkel layers) in the surface region is discussed.