Response of an m.o.s. integrated circuit to tests at elevated ambient temperatures

An earlier exercise seeking life-prediction procedures for complex m.o.s. integrated circuits has been extended, using, as before, a simple integrated circuit, though of different type and origin, as the test vehicle. The acceleration of life is based, as in the earlier work, on the application of electrical stresses at temperatures above the manufacturer´s normal rating. Of the various parameters monitored, the threshold voltages of the constituent transistors again exhibit the greatest response, but the behavioural pattern is markedly different from that previously observed. The changes are explained by the superposition of two counteracting drift mechanisms, one of which is similar to that found in the earlier study. Because multiple failure mechanisms preclude the use of simple Arrhenius lines for life-prediction purposes, a modelling procedure is developed allowing the trends of threshold voltage at constant temperature (as in service) to be calculated from temperature step-stress results. Having, in addition, examined the responses of transistor gain factor and parasitic threshold voltage, earlier proposals for procurement specification requirements are revised and augmented assuming the availability of a suitable test unit manufactured in association with the real components.