Abstract: In a contact metallization employing Mo as a thin‐film ’’diffusion barrier’’, we have observed that this refractory metal does not exhibit optimum barrier properties when rf sputtered in argon. It was found that the use of ∠1500 A of rf‐sputtered Mo between Si and Au results in extensive Si and Au intermixing in <30 min at 450°C. Auger depth profile analysis confirmed that both Si and Au had moved through the Mo. This would preclude subsequent processing involving elevated temperature, as in a Silox deposition. The intermixing appears to proceed via a grain boundary diffusion mechanism (Ea=0.21 eV). Significant improvement in the intermixing time was obtained by the controlled incorporation of N2 into the Mo via reactive rf sputtering. A possible model for this improvement will be presented using the data obtained from microstructural analysis of the nitrided and unnitrided films.

Abstract: A method for constructing systems of refractory layers for use in making gallium arsenide (GaAs) semiconductor devices, having gold as the conducting electrode, which devices are thermally stable when thermally stressed up to about 600° C. for approximately 24 hours. The method forms refractory layers of either tantalum-platinum-tantalum, or tungsten-platinum-tungsten, or titanium tungsten-platinum to develop both the Schottky barrier to GaAs and the diffusion barrier between gold and GaAs. Each of the refractories are individually deposited, at specific temperatures in the range of 50° C. to 175° C., on a GaAs wafer within a vacuum. The metalized wafer cools to room temperature and is removed from the vacuum. Contacts are then typically defined on the wafer and the wafer is subsequently bonded.

Abstract: A multifilamentary stabilized superconductor of the A-15 type is disclosed wherein the A-15 compound is formed on rods of niobium or vanadium by diffusion of tin or gallium, respectively, from a copper alloy matrix and wherein stabilization is provided by an external layer of copper. The stabilizing copper is protected from tin or gallium diffusion by a number of spirally wrapped layers of tantalum separated from one another by copper layers.

Abstract: A low barrier Schottky Barrier Diode (SBD) utilizing a metallurgical diffusion barrier between a transition metal barrier contact and an aluminum base land pattern to prevent interaction therebetween. The diffusion barrier comprises a discretely formed layer of an intermetallic of the transition metal and aluminum.

Abstract: A thin film thermal print head is fabricated using radio frequency (rf) or direct current (DC) sputtering within a vacuum chamber into which is introduced a partial pressure of argon and nitrogen. Without breaking the vacuum, three consecutive layers comprising respectively tantalum nitride, gold, and tantalum nitride are sputter deposited and a diffusion barrier formed on a glazed substrate material. After these steps the desired land patterns are formed by photo lithographic techniques and chemical etching and finally sealant and abrasion resistant coatings are applied.

Abstract: Hybrid microcircuits in geothermal instrumentation must operate from room temperature to 300°C. Bond failure occurred during operation of initial geothermal circuits due to intermetallic growth at the aluminum wire-to-gold conductor interface. To remedy this problem, two wire bonding techniques have been qualified in high-temperature aging tests: 1) ultrasonic bonding of aluminum wire directly to modified fritless gold conductor inks (DuPont 9910, AVX 3520, and TFS A328) and 2) insertion of a I mil diffusion barrier pad between the thick film and the aluminum wire. Both systems allow 100-1000 h operation at 300°C. Three alloys of wire were tested: pure aluminum, aluminum with I percent silicon, and aluminum with 1 percent magnesium. The degradation rates differed greatly with pure aluminum being the least tolerant to temperature aging and wire with 1 percent silicon faring best. Because thick-film surfaces tend to be harder than thin-film surfaces, hardened aluminum wire (elongation 0.5 percent) formed bonds with less pad deformation and, consequently, with higher pull strengths than standard bonding wire (elongation 1-3 percent). Comparison of wire bonds aged at three temperatures (250, 300, and 350°C) demonstrated several orders of magnitude spread in degradation rates; for 1000-h bond lifetime, 300°C was found to be about the highest allowed operational temperature for direct bonding to gold. Disks of kovar and nickel of l-mil thickness and 30 mils diam were used as diffusion barriers between the gold and aluminum. Evaporated on one side of each disk was a 1 µm gold thin film for thermocompression bonding to the thick film; the other side received an evaporated aluminum film for wire bonding. Aging for 1000 h up to 350°C produced no increase in bond resistance for any of the three wire alloys tested. Some decrease in pull strength with time was noticed but was attributed to annealing of the wire.

Abstract: PURPOSE: To establish a solder connection with a high reliability by laminating a metallic layer used for a barrier against the solder diffusion and a metallic layer having an excellent solder applying, on an Au thin film. CONSTITUTION: A Cr 2 and Au 3 are coated on an almina substrat 1 and an etching is provided for a desirable pattern in a reverse order to make a thin film wiring conductor. Successively, A Ni 4 is plated as a solder diffusion barrier by a resist mask on the Au 3. Successively, a Cu 5 with an excellent solder applying and sloder 6 are in turn plated by using the mask on a Ni 4 of the connection terminal to remove a resist. When the solder 6 may be resolved by heating the thin film circuit, the solder 6 remainds in the connection terminal position and is not flown out on the Au 3. This solder connection can be establishe with the Au. The metal for solder diffusion barrier includes Ni, Ti, Mo, W, and Ta effective for it, and Su, Cu, Pb, Zn, Ag are used as the metal with a good sloder applying property. COPYRIGHT: (C)1980,JPO&Japio

Abstract: Diffusion barrier layer (a) for use on heat resistant metals, consists of 2 layers of spinel sepd. by metal layers and covered by an outer metal layer. Three spinel layers, each 3-20 mu m thick, are pref. used, and are sepd. by metals forming spinels, esp. layers of Ni or Fe, the outer metal layer being pref. nickel. The barrier layer prevents the diffusion of tritium (T), esp. in gas cooled high-temp. nuclear reactors, where helium used to remove heat is contaminated with radioisotope gases, esp. T, which must not be allowed to diffuse through e.g. a heat resistant steel tube used in a heat exchanger.

Abstract: Coating systems proposed for potential use on eutectic alloy components in high-temperature gas turbine engines were studied with emphasis on deterioration of such systems by diffusion A 1-mil thick W sheet was placed between eutectic alloys and a NiCrAl layer Layered test specimens were aged at 1100 C for as long as long as 500 hours Without the W barrier, the delta phase of the eutectic deteriorated by diffusion of Nb into the NiCrAl Insertion of the W barrier stopped the diffusion of Nb from delta Chromium diffusion from the NiCrAl into the gamma/gamma prime phase of the eutectic was greatly reduced by the barrier However, the barrier thickness decreased with time; and W diffused into both the NiCrAl and the eutectic When the delta platelets were alined parallel to the NiCrAl layer, rather than perpendicular, diffusion into the eutectic was reduced