Showing papers on "Substrate (electronics) published in 1984"

Thin film transistor

Abstract: PURPOSE:To obtain a transparent thin film transistor having a large ON-current and a memorizing property by a method wherein a transition metal oxide is used as a semiconductor layer. CONSTITUTION:A gate 2 is formed on a substrate 1, then an SiO2 film 3 is deposited on the whole surface, a semiconductor layer 4 is formed, and a source electrode 5 and a drain electrode 6 are formed. Then, an SiO2 film 7 is provided in such a manner that it will not be formed on the electrode 6, and a thin film transistor TFT is formed. In this constitution, a transition metal oxide which is WO3 in other words is used. When WO3 is used for the film 4, its ON-current is approximately two figures higher when compared with the TFT whereon an amorphous semiconductor layer is used. Also, as the WO3 is transparent, a transparent TFT is obtained when a transparent electrode is used for electrodes 2, 5 and 6. Besides, a WO3 thin film can maintain the donor position in the film and the width of a depletion layer for a fixed period even after voltage is cut off, and a memorizing property can also be given to the film.

Modification of the optical and structural properties of dielectric ZrO2 films by ion‐assisted deposition

Abstract: Low‐energy bombardment by argon and oxygen ions has been used in the deposition of thin dielectric films of ZrO2. The film packing density has been improved from 0.83 to unity with a corresponding increase in the refractive index from 1.84 to 2.19. The highest stable refractive index measured was 2.23 for oxygen ion‐assisted deposition of ZrO2 on a substrate heated to 300 °C. Ion bombardment during condensation of evaporated ZrO2 on a room temperature substrate results in crystallization into the cubic phase which is consistent with previous studies of ion impact crystallization by thermal‐spike processes. At elevated substrate temperatures the monoclinic phase is also present.

Electrical and optical properties of zinc oxide thin films prepared by rf magnetron sputtering for transparent electrode applications

Abstract: Zinc oxide films were prepared on unheated glass substrates by rf magnetron sputtering under an applied external dc magnetic field in pure argon gas, and electrical and optical properties of the deposited films were investigated. Highly transparent films with resistivity as low as 10−4 Ω cm, which were weakly oriented perpendicular to the substrate surface(c‐axis orientation), could be produced with a relatively high deposition rate on the substrate suspended perpendicular to the target surface by controlling the sputtering gas pressure and the external dc magnetic field, without any postdeposition preparative treatment. The Hall mobility of the film with the highest conductivity was about 120 cm2/V sec, which was the highest yet reported for thin films on ZnO. The increase in the conductivity was related to the increase in Hall mobility which was caused by the decrease of carrier scattering from grain boundaries due to the grain growth resulting from the improvement of crystallization. The improvement of...

Microminiature semiconductor valve

Abstract: A microminiature valve having a multilayer integral structure formed on a semiconductor substrate. The valve comprises a semiconductor substrate having inlet and outlet apertures and a raised valve seat. The substrate is overlayed with a nonporous top layer and an intermediate layer. The central portion of the intermediate layer is preferentially etched away to form an enclosed chamber connecting said inlet and outlet ports. The unetched portion of said intermediate layer peripherally supports said top layer above the valve seat. An electrically conductive electrode disposed on the unsupported portion of the top layer permits it to be electrostatically deflected to engage the valve seat and close the valve.

Aluminum Nitride-An Alternative Ceramic Substrate for High Power Applications in Microcircuits

Abstract: The development of more complex integrated circuits (IC's) with larger chip sizes and greater power generation IC's, emitter-coupled logic (ECL) circuits, very large-scale integration (VLSI), and laser diodes requires new packaging schemes with improved thermal management. From the limited number of some ten nonmetallic inorganic solids known from the literature to have thermal conductivities greater than 100 W/m°K, aluminum nitride (AIN) is the most attractive substrate material. By means of a suitable power technological process, an AIN ceramic has been produced with a thermal conductivity five times higher than that of alumina, which is about one half of the theoretical value estimated for defect-free single crystal AIN. Another advantage of this newly developed material is its low coefficient of thermal expansion which, in the temperature range of interest (20-200°C) closely matches that of silicon. It also has a high electrical resistivity and a moderate dielectric loss. These and some other physical, mechanical, and chemical properties are shown and partly discussed in relation to other ceramics in use or of potential interest as substrate materials.

Surface softening in silicon by ion implantation

Abstract: Load-variant microhardness tests have been used to investigate the hardness behaviour of ion-implanted (1 1 1) silicon wafers. A variety of ion doses, energies and species, including n-type, p-type and isovalent ions, have been implanted. At the high doses used (1 to 8 x 1017 ions cm2−), all implantations resulted in a surface amorphous layer being formed. The microhardness behaviour has been interpreted in terms of the presence of a surface layer of lower hardness than the substrate. The thickness of this layer has been investigated experimentally using Rutherford backscattering and the results correlated with simple theoretical predictions. Finally, the microhardness behaviour of a soft layer on a harder substrate has been modelled in order to try to predict the hardness variations arising from differing layer thicknesses and different indentation sizes. It is concluded that the amorphous layer produced by implantation appears to show no variation of microhardness with load and has a hardness typically between 400 and 700 Vickers (VHN). Further, the previously reported “critical dose” of ∼ 4 x 1017 ions cm−2 necessary to observe significant surface softening seems to correspond to the regime in which the amorphous layer shows a rapid increase with dose.

A reliable method of alignment for smectic liquid crystals

Abstract: An alignment method for smectic liquid crystals is described. Alignment is obtained by the deposition of a certain class of polymer on a substrate followed by unidirectional rubbing. Only linear polymers capable of being elongated in bulk samples are found to produce alignment. The quality of alignment is found to be exceptionally good and this method can be used to produce alignment over large areas.

Modifications in the phase transition properties of predeposited VO2 films

Abstract: Thin films of the phase transition material vanadium dioxide (VO2) were deposited by thermal oxidation of e‐beam evaporated vanadium on a variety of bulk materials. Substrate effects on transition temperature are confirmed as being due to a mismatch between film and substrate thermal expansion coefficients. Decreasing tensile stress results in a lowering of VO2 transition temperature. Effects of low‐energy Ar+ bombardment on the electrical and optical properties of these predeposited VO2 films were investigated. Bombardment energies in the range 138–500 eV at 1.0–1.3 mA/cm2 for 120–180 s were provided by a Commonwealth Millatron. The higher Ar+ energies resulted in collapse of the VO2 optical transmittance hysteresis loop, while low‐energy Ar+ ions caused both a downward shift in the transition temperature and a decrease in hysteresis loop width, suggesting a dependence of these quantities on intrinsic stress. In addition, large decreases in cold‐state resistivity are reported and attributed to a reductio...

Manufacture of optical disk master

Abstract: PURPOSE:To manufacture an optical disc master small in dropout, and good in S/N ratio at low cost with less steps by irradiating laser beam with a thin dye film formed on a substrate to form a bit, and then washing it. CONSTITUTION:An optically polished glass disk is coated to about 100nm thickness with an ethylene dichloride soln. of 1.25% cyanine dye, such as 2,2'-indo- 6,7,6',7'-dibenzotricarbocyanine using a spinner. A bit is formed by irradiating modulated He-Ne laser beam, and washed with toluene. Since the recording material is insoluble in toluene, and decomposition products produced with laser beam is soluble in toluene, they can be removed. A master is obtained by sputtering silver, electroforming it with Ni, and lining it. As a result, a master small in dropout and good in S/N ratio is obtained at low cost with less steps.

Method for growing monocrystalline silicon through mask layer

Abstract: A monocrystalline silicon layer is formed on a mask layer on a semiconductor substrate. An apertured mask layer is disposed on the substrate, and an epitaxial layer is then grown by a two-step deposition/etching cycle. By repeating the deposition/etching cycle a predetermined number of times, monocrystalline silicon will be grown from the substrate surface, through the mask aperture, and over the mask layer.

Breakdown in silicon oxides (II)—correlation with Fe precipitates

Abstract: Thin silicon oxides of metal‐oxide‐semiconductor (MOS) capacitors were studied by transmission electron microscopy. The MOS capacitors were fabricated on silicon wafers which had been intentionally contaminated by Fe+ ion implantation. It was found that Fe precipitates crossing the SiO2/Si interface penetrated into the silicon oxide from the silicon substrate. They reduced the breakdown strength by inducing singularity points in the silicon oxide.

Large Grain Copper Indium Diselenide Films

Abstract: Large grain thin films of copper indium diselenide with a preferred {112} orientation have been prepared by (i) the deposition of nearly stoichiometric films of copper and indium on suitable substrates using vacuum evaporation or electrodeposition, and (ii) the heat‐treatment of Cu‐In films in a hydrogen‐selenium atmosphere at temperatures above 630°C. The compositional, structural, and electrical properties of the films have been evaluated. In an alternate approach, a copper film on a substrate was first converted into cuprous selenide, followed by the deposition of indium and selenization. The resulting films have the same properties as those from the selenization of Cu‐In films.

Magnetic recording medium

Abstract: PURPOSE:To obtain a high-density recording medium which provides a particularly high reproduced output by providing >=2 layers of magnetic layers, incorporating ferromagnetic hexagonal ferrite powder in the outermost magnetic layer and specifying the square ratio of the hexagonal ferrite layer in the vertical direction of the magnetic recording medium at a specific value of above. CONSTITUTION:A magnetic recording medium is formed by laminating and forming >=2 layers of magnetic layers contg. pulverized ferromagnetic powder and a binder as an essential component of a nonmagnetic substrate. A magnetic coating is coated on the substrate of such recording medium in such a way that the outermost magnetic layer contains hexagonal ferrite such as BaO.6Fe2O3 or the like and a binder as an essential component and that the square ratio thereof attains >=0.7 in the vertical direction of the magnetic recording medium. The substrate is thereafter passed between the magnets provided above and below the same to orient the magnetic layer before the coating dries. Co-contg. Fe2O3, CrO2, ferromagnetic alloy powder, etc. are used for the magnetic layer under said magnetic layer. The lower magnetic layer is provided as the magnetic flux from a head is hard to form a closed loop with only the hexagonal ferrite layer in the outermost part. The high-density recording medium which is improved in the reproduced output with a ring type head is thus obtd.

X‐ray photoelectron spectroscopy study of the chemical structure of thermally nitrided SiO2

Abstract: X-ray photoelectron spectroscopy has been used to study the composition of 100-A thermally grown SiO2 films that have been thermally nitrided in ammonia. The SiO(x)N(y)/Si interface was studied both by chemical depth profiling of the oxynitride and by removal of the Si substrate with XeF2. It is found that N is distributed throughout the film, but with the concentration higher at the surface and in a region centered 25 A from the film/substrate interface. The interface region itself is found to be oxygen-rich relative to the rest of the film. Possible models which can explain these results are discussed.

Electrophotographic sensitive body

Abstract: PURPOSE:To obtain an electrophotographic sensitive body lowered in friction coefft., improved in cleaning characteristics, and superior in durability, and capable of forming a high quality image always free from ground stains by forming a surface layer contg. a fluororesin capable of forming a film by coating. CONSTITUTION:An electrophotographic sensitive body has a surface layer formed by hardening a fluororesin capable of forming a film in the presence of a crosslinking agent, such as butylated melamine or isocyanate, and said fluororesin is a copolymer of fluorolefin, and alkylvinylether, or a monomer having a carboxylic acid ester group, such as CF2=CFO(CF2)3COOCH3. Said surface layer means the upper most layer, for example, an electrostatic charge transfer layer 13 formed on the charge generating layer on a conductive substrate (the case a), or on the contrary, the uppermost layer 12 formed reversely on the layer 13 (case b), and when a protective layer 14 is formed on a single photoconductive layer or a laminated photoconductive layer, it means this protective layer 14 (case c).

Manufacture of semiconductor device

Abstract: PURPOSE:To obtain a semiconductor device with improved high temperature characteristics by a method wherein when a groove is formed on the surface of a semiconductor substrate and a glass insulation layer is adhered to the inside of the groove and the edge of the aperture, zinc system glass is introduced as the glass and the glass layer is covered with a silicon nitride film and an electrode forming portion of the surface of the substrate is processed by surface treatment. CONSTITUTION:A groove 13 is formed on the surface of a semiconductor substrate 11 and an insulation material 14 made of Zn system glass is electrolytically adhered to a P-N junction 12 exposed in the inside wall of the groove 13 and to the circumference of the aperture. The material 14 is left on the SiO2 film 15 as small particles 16 but they will have no problem because they will be removed by the following selecting etching process. Then the substrate 11 is baked at the required temperature and the material 14 is turned to a glass layer 17 and an Si3N4 18 is formed on the film 15 and the glass layer 17. A photoresist film 19 is formed on the surface other than the region where the electrode is formed and the film 15, with small particles 16 adhered on it, is removed by etching.

Atomic Layer Epitaxy

Abstract: This review discusses the development and present status of atomic layer epitaxy (ALE), a technology for growing layers of crystalline and polycrystalline materials one atomic layer at a time. Atomic layer epitaxy was originally developed to meet the needs of improved ZnS thin films and dielectric thin films for electroluminescent thin film display devices. Accordingly, early work on ALE was mainly carried out for thin films. During the 80s there has been a growing interest in applying ALE in the growth of single crystals of III–V and II–VI compounds and ordered heterostructures such as layered superalloys and superlattices. ALE has also been extended to the growth of elemental single crystals. A basic advantage of atomic layer epitaxy is in the increased surface control of the growth. This is achieved by combining a sequential reactant interaction with a substrate at a temperature which prevents condensation of individual reactants on the growing surface. This results in a stepwise process where each reactant interaction is typically saturated to a monolayer formation. Accordingly, the rate of the growth in an ALE process is determined by the repetition rate of the sequential surface reactions, and the thickness of the resulting layer is determined by the number of reactant interaction cycles. This self-controlling feature of atomic layer epitaxy ensures excellent uniformity of the thickness over large substrate areas even on non-planar surfaces. Owing to its principle of operation, ALE is especially suitable for producing layered structures of III–V and II–VI compounds. Superlattice structures of both these material groups have already been demonstrated. As a limiting case of superlattices, layered superalloys have also been grown. In ALE, chemical reactions producing a material, are divided into separate subreactions between a vapor and a solid surface, each of which results in a new atomic layer of the material. From the theoretical point of view ALE offers a unique link between theoretical and experimental chemistry by permitting direct observations of subreactions under conditions where the chemical environment is more precisely determined than in conventional continuous reactions.

Fiber-waveguide self alignment coupler

Abstract: An optical fiber-to-waveguide coupler is disclosed which automatically aligns five of the six possible degrees of freedom associated with the alignment process. Silicon v-grooves (22) are used to hold the fibers (24) in place in the silicon substrate (20), but in contrast to prior art arrangements, the silicon substrate overlaps the top surface (12) of the waveguide substrate (14). A cover plate (26) disposed over the silicon substrate is cut and polished so that the endface of the cover plate (28) lies in the same plane as the ends of the fibers (30). When the endface of the cover plate is butted against the endface (16) of the waveguide substrate, and the silicon v-grooves have been etched to the proper predetermined depth, five of the six degrees of freedom are automatically aligned.

Low resistivity tungsten silicon composite film

Abstract: A composite film is provided which has a first layer of WSix, where x is greater than 2, over which is disposed a second layer of a tungsten complex consisting substantially of tungsten with a small amount of silicon therein, typically less than 5%. Both layers are deposited in situ in a cold wall chemical vapor deposition chamber at a substrate temperature of between 500° and 550° C.. Before initiating the deposition process for these first and second layers, the substrate onto which they are to be deposited is first plasma etched with NF3 as the reactant gas, then with H2 as the reactant gas, both steps being performed at approximately 100 to 200 volts self-bias. WSix is then deposited onto the surface of the substrate using a gas flow rate for silane which is 20 to 80 times the flow rate of tungsten silicide, followed by deposition of a tungsten complex as the second layer, using a gas flow rate for tungsten hexafluoride which is 1 to 3 times the flow rate of silane, and a gas flow rate of hydrogen which is about 10 times the flow rate of silane. Similarly, in another embodiment, the tungsten complex without the silicide layer is deposited directly onto a silicon surface using the same process as for the tungsten complex in the second layer of the first embodiment.

Thermally insulating glazing

Abstract: A method of producing glass sheets having good transmission behavior in the visible spectrum range and having good reflection behavior as regards heat radiation. A transparent substrate S is coated by cathodic atomization with, successively, a first oxide layer 1 comprising indium oxide, tin oxide or mixtures thereof, a layer 2 consisting of silver in a thickness of 5 to 50 n, a metallic layer 3 selected from aluminium, titanium, tantalum, chromium, manganese and zirconium in a thickness ranging from 1 to 5 nm and applied directly to the silver layer 2 for the purpose of maintaining the condition thereof, and a final protective oxide layer 4 of indium oxide, tin oxide or mixtures thereof.

Selective epitaxial growth method

Abstract: Disclosed herein is a selective epitaxial growth method for forming an opening, utilizing anisotropic dry etching, in a silicon oxide film formed on a silicon substrate and epitaxially growing a silicon layer selectively in the opening. The anisotropic dry etching is performed employing a mixed gas of carbon tetrafluoride and hydrogen, and the wall surface of the opening is perpendicular to the major surface of the silicon substrate. The epitaxial growth is achieved under a temperature of 900° to 1100° C. utilizing a mixed gas of a low pressure under 100 Torr. containing dichlorosilane as a silicon source and hydrogen as a carrier gas. A silicon layer thus obtained contains substantially no lattice defects such as a stacked fault.

Evidence for microstructural inhomogeneity in sputtered Co‐Cr thin films

Abstract: Thin films of the perpendicular recording material Co100−xCrx(x=17–23) were ion beam sputtered from alloy targets. The saturation magnetization and uniaxial anisotropy constant, as a function of temperature, both show a strong dependence on the substrate temperature during deposition Ts, indicating composition shifts which increase with Ts. The films have a columnar structure on a scale which does not depend on Ts in contrast to the grain size. From studies of the phase relations in bulk Co‐Cr alloys and diffusion couples it is concluded that phase separation of ordered Co‐Cr phases does not occur at high Ts. Instead the composition shifts and the grain refinement at higher Ts are proposed to be caused by oxygen gettering and oxide trapping during film growth.

Semiconductor integrated circuit device

Abstract: PURPOSE:To prevent formation of channel at the side surface by forming an impurity layer for preventing channel at the side surface on the side surface, depositing a field insulating film, covering the surface of substrate with a material having smooth surface and by forming at a time a field insulating film. CONSTITUTION:An impurity in the same conductivity type as the substrate is formed by the ion implantation, a guard ring impurity layer 13 is formed at the lower part of the surface of substrate, shallow and low concentration impurity in the same conductivity type as the substrate is thermally diffused only to the surface region of the side surface 10a with an oxide film 11 used as the mask, and an impurity layer 14 for preventing channel at the side surface is formed. After forming an oxide film 15 which will become the field insulating film, a photo resist material 16 is coated. The material 16 makes smooth the uneven surface. The entire part of this surface is etched using the reaction sputtering apparatus of CF4 system gas until the oxide film 11 is exposed.

A novel structure, high conversion efficiency p-SiC/graded p-SiC/i-Si/n-Si/metal substrate-type amorphous silicon solar cell

Abstract: A novel structure, high conversion efficiency amorphous silicon (a‐Si)/metal substrate‐type solar cell has been developed. The new structure, deduced from the conventional pin junction by the use of a gradual compositional grading p‐type a‐SiC:H layer between an ultrathin (∼20 A) wide optical band gap (∼2.4 eV) p‐type a‐SiC:H layer and the i layer, exhibits markedly enhanced open‐circuit voltage (Voc) and short‐circuit current density (Isc) over the conventional a‐Si pin/substrate‐type solar cell. Especially, the collection efficiency in the newly developed structure was found to be remarkably increased at short wavelengths. The experimentally observed improvement in the blue response is due to the reduction in effective interface recombination combined with the enhanced window effect. An energy conversion efficiency of 8.40% under air mass (AM) 1 (100 mW/cm2) illumination has been obtained in the first trial of a cell fabricated by the rf glow discharge decomposition of pure silane (SiH4).

Electrophotographic sensitive body

Abstract: PURPOSE:To provide high sensitivity at a short wevelength and high moisture resistance by forming further an amorphous silicon (a-Si:F) layer laminated to a specific film thickness on a conductive substrate. CONSTITUTION:Amorphous silicon (a-Si:H) contg. hydrogen is laminated to a prescribed thickness on a conductive substrate and gaseous fluorine having high purity is ionized in a vacuum and the ions are implanted to the a-Si:H layer to form the a-Si:F layer having a prescribed thickness. Since F has higher affinity to Si than H, the F implanted into the a-Si:H layer is bonded with Si to form an Si-F bond. The a-Si:F film having a high grade is thus formed and the electrophotographic sensitive body coated with the a-Si:F film having high moisture resistance is obte. The film thickness of the a-Si:F layer is preferably in a 0.1- 5mum range to obtain desired photosensitivity. Formation of the uniform film is difficult at <=0.1mum and the photosensitivity is deteriorated on the contrary if the thickness exceeds 5mum.

Integrated three-dimensional localized epitaxial growth of Si with localized overgrowth of GaAs

Abstract: Localized epitaxial growth of GaAs from a silicon monocrystalline substrate to provide a three-dimensional Si-GaAs structure and method. The silicon has an insulating layer deposited thereover and a window is opened through the layer to expose a small area of the underlying silicon from which silicon is epitaxially grown until the window is nearly full whereupon a thin buffer layer such as germanium is epitaxially grown over the epi-silicon to fill the window. Al x Ga 1-x As (where x≧0) is then locally epitaxially grown from the buffer layer and it grows laterally as well as vertically to cover the surrounding insulating layer surface and provide a site for high frequency electronics.

Method for producing hyperabrupt doping profiles in semiconductors

Abstract: A method for achieving extreme and arbitrary doping profiles in semiconductors with dopant concentrations varying over orders of magnitude in a few atomic layers The method involves evaporating the semiconductor, along with the desired amounts of n- or p- dopants onto an atomically clean substrate semiconductor surface in an ultrahigh vacuum environment at low temperatures such that an amorphous film results The amorphous film is then crystallized epitaxially by a solid phase epitaxy, thereby providing a single crystal with the desired dopant profile Multiple profile changes or grading may be included in the semiconductor film by varying dopant concentrations in the amorphous layer as desired

Manufacture of semiconductor device

Abstract: PURPOSE:To simplify the manufacturing process of a semiconductor device and to contrive reducing the time for the manufacture by carrying out an alumi num evaporation process and an aluminum sintering process simultaneously in one process at a specific temperature for the evaporation of aluminum on a semiconductor substrate CONSTITUTION:A semiconductor substrate which was sufficiently washed in a previous process is set at a definite position in an evaporation equipment Then, the inside of the evaporation equipment is made a vacuum and the semi conductor substrate is heated by a heating source to above 250 degC, eg, 250-300 degC The aluminum source provided in the evaporation equipment is evaporated by heating and adheres to the surface of the semiconductor substrate For example, only approx 15-20 minute processing is required for forming an evaporation layer 05 mum thick Then, even in the case of evaporating the other metal on the aluminum evaporated layer formed in the above-mentioned process, the semiconductor substrate which is being heated is processed Further, the sintering of aluminum is still being continued even during this period and no higher temperature is required for the temperature itself of heating

Process for depositing a low resistivity tungsten silicon composite film on a substrate

Abstract: A composite film is provided which has a first layer of WSix, where x is greater than 2, over which is disposed a second layer of a tungsten complex consisting substantially of tungsten with a small amount of silicon therein, typically less than 5%. Both layers are deposited in situ in a cold wall chemical vapor deposition chamber at a substrate temperature of between 500° and 550° C. Before initiating the deposition process for these first and second layers, the substrate onto which they are to be deposited is first plasma etched with NF3 as the reactant gas, then with H2 as the reactant gas, both steps being performed at approximately 100 to 200 volts self-bias. WSix is then deposited onto the surface of the substrate using a gas flow rate for silane which is 20 to 80 times the flow rate of tungsten silicide, followed by deposition of a tungsten complex as the second layer, using a gas flow rate for tungsten hexafluoride which is 1 to 3 times the flow rate of silane, and a gas flow rate of hydrogen which is about 10 times the flow rate of silane. Similarly, in another embodiment, the tungsten complex without the silicide layer is deposited directly onto a silicon surface using the same process as for the tungsten complex in the second layer of the first embodiment.