World Abstracts on Microelcctronics and Reliability
position reproducibility, productivity and reliability. For achieving optimum results in all these parameters it is imperative to have a precise optical mechanical system that is controlled by reliable electronic circuitry.
Investigation of the Au-Gc~Ni system used for alloyed contacts to GaAs. M. WITTMER,R. PRETORILS, J. W. MAYER and M. A. NICOLET. Solit-St. Electron. 20, 433 (1977). The Au G e N i metallization scheme is widely used for alloyed contacts to GaAs. We have studied the interaction of these three elements upon heat treatment using an inert substrate. Our investigations showed that Ni acts as a sink for Ge in that the Ge diffuses out of the Au, with which it is usually coevaporated, into the Ni layer where it forms stable compounds. Apart from a small amount of Au diffusion into the Ni, there is no interaction between these two elements. We have also found that the ratio of the amount of evaporated Ge to that of Ni is important if uniform layers are anticipated. Growing pin count is forcing LSI package changes. JERRY LYMAN. Electronics. p. 81 (March 7, 1977). At high pin counts, DIPs waste board space so designers are trying chip- and film-carriers. High purity chemicals in semieon production. KENNETH G. CLARK, E. MALCOLM JULEFF, and STEPHEN FAWCETT. Electron. Prod. p. 43 (April 1977). In the field of wet processing chemicals "Electronic" or "Semiconductor" grade materials have been available for a number of years and have been widely used in the Microelectronics Industry especially by the manufacturers of MOS and surface effect integrated circuits. These chemicals have been manufactured worldwide by leading chemical companies in bulk quantities and in this bulk state have been able to meet their published specifications however, in the methods employed for bottling and in the bottles themselves inorganic solids and metallic materials have been added to the liquid chemicals often in significant quantities of impurities and being measured at many hundred to tens of thousands of particles at a whole range of sizes from sub-micron to 50 itm or greater particle size and at impurity levels of 1.00 to 1.00 ppm of a given inorganic impurity. Some of these chemicals also contain the origin salts at a relatively high impurity level, for instance Ammonium Fluoride solution (the largest volume component in SiO2 etchants) normally contains several ppm of solid calcium salt in its originating raw material calcium tluoride. A study has been made of both the particulate matter found in bottled "Electronic/Semiconductor" grade chemicals and the impurity levels found, both of which deviate in all cases from the manufacturers specification for the chemical solution. Gallium arsenide spawns speed. RORY VAN TUYL and CHARLES L1ECHTI. IEEE Spectrum p. 41 (March 1977). 6. M I C R O E L E C T R O N I C S - - C O M P O N E N T S ,
Universal logic element or "superfunction" arrays. S. L. HURST. Microelectron. 8, (2) 13 (1977). The "superfunction" concept for LSI uncommitted logic arrays raises the logic power of the uncommitted cell from the primitive level of separate active and passive devices, as in current use, to a level higher even than the row and column logic elements within P R O M and PLA circuits. Some simple applications are considered, to illustrate how superfunction cells may be hardwire-programmed to realize certain given functions. Further investigation is needed for determining which form of superfunction is to be preferred in a given LSI technology as regards speed, power and chip area.
High-frequency circuit and system designers no~ have an important new tool ill their arsenal of technologies. Monolithic gallium-arsenide (GaAsJ digital ICs have emerged, bringing with them the promise of muhigigabit and higher data rates beyond the reach of present silicon-based rotegrated circuits. Applied to future systems, the new circuits would go a long way toward slashing the size, weight, and eventually the cost of high-flequency electronic equipment- and. m the process, vastly enhancing the capabilities of equipment spanning the commercial and military worlds.
Surface and bulk electrical conduction in low-depositiontemperature Si3N 4 and A1203 films for silicon devices. ROBERT B. COM1ZZOLI. RCA Reciew 37, 473 (December 1976t. Surface and bulk conduction of AI:O 3 and Si3N.~ films produced by low-temperature processes ( < 4 5 0 C / were measured. These properties ot the deposited layers were compared with those of chemical vapor deposited SiO z and phosphosilicate glass of the type commonly used for integrated-circuit passivation. The performance and reliability implications of the electrical properties, particularly in the presence of water, are discussed, and the need for further evaluation is pointed out. Press fit pins in printed circuit boards second test series. P. J. TAMBURRO. Proc. Electron. Components CoJ~fi Arlington, Va., May 16 18, 1977. p. 283. An initial series of press fit pin tests has been followed by a second series to answer four questions: 1. Can a quick test replace the longer procedure used initially (since no significant changes occurred until the 33 day aging and sulphur dioxide tests during the first test series)'? 2. Is there any significant difference between pins pressed into boards, pins reflow soldered with solder preforms, and reflowed with just the plated solder? 3. ls there any change in normal force of cantilever contacts against a printed wiring board when subjected to environmental stress'.' 4. Are press fit connections stable in 0.093" thick boards as well as in 0.125" thick printed circuit boards'? Automated shock in particle impact noise (PIN) testing. L. A. SCHREIER. Proc. Eh,etron. Components Conf Arlington, Va., May 16 18. 1977. p. 169. A major problem with particle impact noise tPIN) testing is that included particles tend to become immobilized inside the package by electrostatic forces or entrapment in internal package crevices. Mechanical shock has been used to dislodge these particles. However, the level of this shock is difficult to control precisely. This paper describes a method for imparting known shock levels during PIN testing thru pulsed accelerations to the shaker table. The pulses are introduced electronically fi'om the shaker table drive circuitry. A description of this circuitry and fine results of experiments on several packages salted with known particles arc presented. SYSTEMS
Single C-MOS-IC forms pulse-width modulator. MARK E. ANGLIN. Electronics p. 126. June 23, 1977. A pulse-width modulator can be constructed with a single complementary-metal-oxide-semiconductor integrated circuit if the ~c's field-effect transistors control the duty cycle of a freerunning oscillator. The output resistance of the EET varies almost linearly with input voltage over portions of its characteristic curve, permitting the circuit to be used for applications in switching power supplies and analog conversion in data-communications systems.