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Strain sensors that can be switched on and off were fabricated from p-channel IGFET on thin filament n-type silicon crystals with silicon dioxide layer sputtered over transistor for passivation. Applications include integration with microelectronic circuits for multiplexing.
Brief discussions of the techniques used to make dielectric and metal thin film depositions for monolithic circuits are presented. Silicon nitride deposition and the properties of silicon nitride films are discussed. Deposition of dichlorosilane and thermally grown silicon dioxide are reported. The deposition and thermal densification of borosilicate, aluminosilicate, and phosphosilicate glasses are discussed. Metallization for monolithic circuits and the characteristics of thin films are also included.
The design data for six polycrystalline dielectric materials are presented to describe the optical, thermal, and mechanical properties. The materials are aluminum oxide, calcium fluoride, magnesium fluoride, magnesium oxide, silicon dioxide, and titanium dioxide. The primary interest is in the polycrystalline state, although single crystal data are included when appropriate. The temperature range is room temperature to melting point. The wavelength range is from near ultraviolet to near infrared.
On the basis of data provided by the IR interferometer spectrometer on the Mariner 9 spacecraft, it is suggested that the composition of the Martian dust corresponds approximately to that of rocks of intermediate silicon dioxide content. The large dynamical pole flattening obtained from satellite observations has been confirmed by the Mariner 9 data.
Van der Pauw or bridge samples are ultrasonically cut from silicon on sapphire wafers. Contact pad regions are implanted with moderately heavy dose of ions. Ion of interest is implanted into sample; and, before being annealed in vacuum, sample is sealed with sputtered layer of silicon dioxide. Nickel or aluminum is sputtered onto contact pad areas and is sintered in nitrogen atmosphere.
Lunar samples 60017,4 and 63335,14 are composed of microbreccias and devitrified glass. These components are predominantly anorthositic, with the exception of a cryptocrystalline clast found in the microbreccia portion of 63335,14 which contains 2.7% potassium oxide and 66.7% silicon dioxide. The samples have been subjected to extreme shock and thermal metamorphism. The parent materials of the microbreccias include both a coarse-grained anorthosite and a fine-grained subophitic anorthositic gabbro.
An experiment was made to determine the effect heterogeneous catalytic surface reactions have on heat-transfer rates in highly frozen low-density stagnation-point boundary layers. Data were obtained in arc-heated facilities that were capable of producing large percentages of chemical energy frozen in a supersonic freestream. The heat-transfer rate to a silicon-dioxide surface was reduced to a minimum value of only one-third of the value obtained on relatively active nickel and platinum surfaces. This is the result of its low catalytic efficiency. Ionization energy was recovered on both the active and the inactive surfaces, indicating that this energy either was released many times faster than the recombination energy or was not controlled by the surface composition.
A series of impact tests are described and data presented which characterize the operation of the capacitor-type micrometeoroid flux detectors used on the Meteoroid Technology Satellite (MTS). Capacitor-type detectors with silicon dioxide dielectric thickness of 0.4 and 1.0 microns were tested in the micrometeoroid impact simulator at the Langley Research Center, a 4-MV Van de Graaff electrostatic accelerator. The carbonyl iron projectiles were from 0.5 to 5.0 microns in diameter with velocities from 4 to 10.0 km/sec. The detector bias voltage was varied from -20 to -60 V; some tests were at detector temperatures of 90 C to -100 C; and the angle of impact varied from 0 deg to 75 deg from the normal to the detector. These tests showed that: (1) the detector operation is reliable when the bias voltage is greater than 30 V; (2) after an impact the detector returns to its original condition with an insignificant loss of active area; and (3) the sensitivity of the detector is inversely proportional to the detector thickness. The test results suggest a theoretical model in which the signal is an arc triggered by the impacting projectile, and the detector bias voltage must be high enough to insure that an arc will form.
Models of the major planets are in part based on the equations of state of very compressible materials such as hydrogen and helium. A technique of isentropically compressing soft material to several Mbar and some preliminary results on fused quartz (silicon dioxide) and liquid hydrogen is described. Quartz was found to be an electrical non-conductor up to 5 Mbar and has a volume of about 0.15 cubic centimeters per gram at that pressure. Liquid hydrogen was found to have a volume of about 1 cm3/g at a pressure of about 2 Mbar. It was not determined if it was transformed into a metal.
The preparation of chemically resistant and flame retardant foams from polyfunctional aromatic carboxylic acid derivatives and organic polyisocyanates is outlined. It was found that polyimide foams of reproducible density above 1 lb./ft. and below 6 lbs./cu ft. can be obtained by employing in the reaction of least 2% by weight of siloxane-glycol copolymer as a surfactant which acts as a specific density control agent. Polyimide foams into which reinforcing fibers such as silicon dioxide and carbon fibers may be incorporated were also produced.
Two processes for the fabrication of beam-leaded COS/MOS integrated circuits are described. The first process utilizes a composite gate dielectric of 800 A of silicon dioxide and 450 A of pyrolytically deposited A12O3 as an impurity barrier. The second process utilizes polysilicon gate metallization over which a sealing layer of 1000 A of pyrolytic Si3N4 is deposited. Three beam-lead integrated circuits have been implemented with the first process: (1) CD4000BL - three-input NOR gate; (2) CD4007BL - triple inverter; and (3) CD4013BL - dual D flip flop. An arithmetic and logic unit (ALU) integrated circuit was designed and implemented with the second process. The ALU chip allows addition with four bit accuracy. Processing details, device design and device characterization, circuit performance and life data are presented.
Progress is reported on the development of a high purity reflective heat shield material. Silicon dioxide was selected as the material because it is highly reflective in the correct wavelength band, has good ablation characteristics, is thermal shock resistant, and is readily fabricated to full size at reasonable cost. Conclusions indicate that: reflectance is affected by purity and morphology; the pure material is readily available; required purity and morphology can be maintained with reasonable care; high reflectances are determined (0.99 from 0.4 to 1.2 microns); major processing steps are defined; and the material appears to be cost effective. It is indicated that the materials are developed to the point of readiness for full scale fabrication and characterization.
Recent results on tunneling in thin MOS structures are described. Thermally grown SiO2 films in the thickness range of 22-40 A have been shown to be effectively uniform on an atomic scale and exhibit an extremely abrupt oxide-silicon interface. Resonant reflections are observed at this interface for Fowler-Nordheim tunneling and are shown to agree with the exact theory for a trapezoidal barrier. Tunneling at lower fields is consistent with elastic tunneling into the silicon direct conduction band and, at still lower fields, inelastic tunneling into the indirect conduction band. Approximate dispersion relations are obtained over portions of the silicon-dioxide energy gap and conduction band.
Contaminated oxide cells have been fabricated with efficiencies of 8.6% with values of I sub sc = 120 ma, V sub oc = .54 volts, and curve factor of .73. Attempts to optimize the fabrication step to yield a higher output have not been successful. The fundamental limitation is the inadequate antireflection coating afforded by the silicon dioxide coating used to hold the contaminating ions. Coatings of SiO, therefore, were used to obtain a good antireflection coating, but the thinness of the coatings prevented a large concentration of the contaminating ions, and the cells was weak. Data of the best cell were .52 volts V sub oc, 110 ma I sub sc, .66 CFF and 6.7% efficiency.
Family of inorganic binders utilizes potassium or sodium oxide/silicate dispersion and employs high mole ratio of silicon dioxide to alkali-metal binder. Binders are stable, inexpensive, extremely water resistant, and easy to apply.
Coating of mixed ceramics protects tungsten from oxidation. Originally suggested for critical tungsten components on Space Shuttle, mixture consists of 98.5 percent aluminum oxide and 1.5 percent silicon dioxide. It is particularly useful in welding when there is danger that welding arc can burn adjacent components. If coating is applied to nearby tungsten parts, it prevents arcing.
A technique for growing limited-length ribbons continually was demonstrated. This Rigid Edge technique can be used to recrystallize about 95% of the polyribbon feedstock. A major advantage of this method is that only a single, constant length silicon ribbon is handled throughout the entire process sequence; this may be accomplished using cassettes similar to those presently in use for processing Czochralski waters. Thus a transition from Cz to ribbon technology can be smoothly affected. The maximum size being considered, 3 inches x 24 inches, is half a square foot, and will generate 6 watts for 12% efficiency at 1 sun. Silicon dioxide has been demonstrated as an effective, practical diffusion barrier for use during the polyribbon formation.
Materials were surveyed to provide candidates for an all metal electrode paste system. These consisted of a major constituent metal powder, a low melting metal powder suitable for a liquid phase sintering medium, and a powder material suitable as an etchant for silicon dioxide at sintering temperatures. By means of thermal gravimetric analysis a suitable binder was identified for low temperature fired inks.