Preparation and properties of plasma-anodized silicon dioxide films

World Abstracts on Microeleetronics and Reliability practice, resistor batch mean values can he kept within 5 per cent from day to day. A printing process with these characteristics reduceg, or even eliminates, trb~ming requirements. The insensitivity of resistance to printer p a r a m e ~ s canno¢ b e explained by generally accepted theories predicting that the quantity of ink pushed into the screen depends heavily on these parameters. However, it has been demonstrated experimentally that the volume of ink deposited on the substrate depends primarily on the interaction forces between the screen, substrate and ink. An hypothesis is formulated to show that, providing adequate ink is fed into the screen, the equilibrium between these forces acts as a self-compensating mechanism responsible for a uniform deposited volume over a wide range of printer settings. Fabricatien ~ fee hfm'ld e d ¢ ~ R. Y. SCAPPLEand F. Z. K I ~ T ~ . Proc. IEEE 1974 24th Electron. Compon. Conf. Washington D,C. 13-15 May 186 (1974). The purpose of the Fabrication Aid is to reduce the cost of fabricating thin film hybrid microcircuits. It accomplishes this by reducing labor costs and by minimizing assembly errors, The Fabrication Aid has been shown to reduce recurring labor costs by about 19 per cent. i n essence, the Fabrication Aid is a means of micro-printing fabrication instructions directly on the thin film substrate. The information is permanent and remains throughout the life of the unit. The technique involves the application of a photosensitive material to the substrate, which is then photo-exposed and developed through an appropriate mask. This defines the identification and instruction markings. At this point the photosensitive material is nearly transparent and not legible. As a final step, the pattern is darkened to give it the necessary visual contrast with the remainder of the substrate. Darkening is done by a gradual elevated temperature exposure in air. Legibility, when viewed under a microscope, is analogous to conventional printing on a newspaper when viewed by the unaided eye. Low temperature processing for hi-tel multi-chip hybrids. T. B. GILLISand R. E. LASH. Proc. IEEE 1974 24th Electron. Compon. Conf. Washington, D.C. 13-15 May 181 (1974). For many years the conventional process used at Raytheon for the assembly of microelectronic hybrid modules was the screen printed, thick-film, eutectic die attach and thermocompression gold-ball bonding process. While this process has had proven success and has proven reliability as hybrid modules became more complex (25 active I.C.'s per module), module yield problems were encountered because of the degradation of the semiconductor chips after being exposed to high processing temperatures for the increased length of time required to complete the assembly. In an effort to prevent this, a new series of processing techniques were introduced where the eutectic die attach was replaced with epoxy, the thermo-compression bond was replaced with a gold ultrasonic bond and the final gold-tin brazed seal replaced with a parallel seam weld. In the new process, the active chips are never exposed to temperatures in excess of 150~C. Modules were assembled using the new low-temperature process and exposed to a variety of environmental and life tests to determine if the new process was as reliable as the conventional process. After Environmental and 1000 hr Life tests, the modules appeared to be equally as reliable and tests on wire bond strength, die attach strength, thermal conductivity indicate the low-temperature process to be

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equal in reliability to the conventional process and offers the added advantage of improved yields during volume manufacturing.

Thiy thin-Aha e l ~ resistors. Microwave J. 34 (1974). Small size, combined with excellent performance, are two key advantages offered by this series of thin-film chip resistors available off the shelf. Measurements are 0-025 x 0.050 in.; fabrication is on a 99.5 per cent alumina substrate of 0.010-in. thickness. The small size facilitates the mi-imumlength resistive area required for stable operation at microwave frequencies. These resistors are useable up to 18 GHz. Care must be exercised in mounting the units for operation at any frequency in order to ensure high performance, and extreme care in mounting must be taken when operation is intended between 12 and 18 GHz. When such precautions are taken, SWR performance of < 1.5 can be achieved to 18 GHz. Thermal and radia~en petarizatien in organic dielectric films. E. BOTH. Proc. IEEE 1974 24th Electron. Comport. Conf. Washington, D.C. 13-15 May 208 (1974). The polarization behavior of poly(ethylene terephthalate), polycarbonate and polysulfone has been determined in response to treatments with applied electric bias at elevated temperature and in a 6°Co 7-radiation field at room temperature. Characteristic differences are found in the magnitude of~the polarization and its stability against thermal discharge for the different materials as well as for the different treatments. The radiation polarization is generally proportional to the exposure but remains well below the level attained by the thermal treatment, apparently because radiation damage prevents its buildup beyond a certain exposure. The smallest response to both treatments is found in polycarbonate with about 10 times larger values in poly(ethylene terephthalate) and about twenty times larger in polysulfone. The quantitative results are of interest for the use of capacitors and other dielectric devices in a nuclear radiation environment and provide a basis for worst-case estimates. Preparation and properties of pltsmm4mdized silicon dioxide films. D. L. PUL~L~Y and J. J. H. R~z.~. Solid St. Electron. 17, 627 (1974). The preparation and properties of thin films of silicon dioxide formed at 200°C by anodization in an RF plasma are described. A suitable procedure for obtaining good quality films is given along with information on the effects of film sputtering and internal stress buildup during anodization. Measurements on MOS capacitors utilising the plasma-grown oxide yielded information on oxide charges, Si/SiO 2 interface state density, oxide permittivity leakage resistance and film breakdown strength. Additional measurements determined the physical properties of stochiometry, impurity content, refractive index and etching behaviour. The plasma-anodizad films can be routinely grown to a quality comparable with the best thermallygrown oxides. A kermetledy sealed 20,GI~ lategrated m ~ r . T. ARArJ, M. HmAY^MA, N. Fun~m and T. ~ . NEC Res. Develop. 81 (Apr. 1974). An integrated balanced mixer for a 20-GHz band PCM transmission systemwas developed. One of the main subjects of study was how to seal microwave integrated circuit (MIC) devices to be connected to the external waveguide circuits. The MIC substrate, where GaAs Schottky-barrier diode chips were directly mounted, was hermetically enclosed with a metallic package providing