Life tests of SSI integrated circuits

Some results as well as a new and simple method of digital IC life testing are dealt with here referring to the beginning of a large-scale test programme which started 2 yr ago. As the first step, bipolar SSI digital IC-s of the TTL, DTL and RTL series have been considered comprising about 60 million device-hr, life-tested by various long-run stress methods as temperature storage, d.c.-and switching-service operational tests to gain a fair picture on main failure mechanisms, the nature and shift tendencies of parameter distributions as well as on the activation energy of degradation processes—besides the estimation of characteristic failure rates in various stress forms—to facilitate the use of accelerated methods and to rendering possible the optimal choice among testing methods for future reliability assessment work. It has been shown that temperature activation energies of approx. 1·0 eV—essentially the same as at discrete planar transistors—are resulted if “side” effects of experiments are carefully avoided.