NMOS Voltage Breakdown Characteristics Compared with Accelerated Life Tests and Field use Data

Statistics on voltage-accelerated failures of 4K NMOS RAM´s have been compared with accelerated life test data and with real field use data. It is concluded that it is possible to get long-term reliability information from fast overvoltage step stress tests such as 40 ms and 1.2 s dwell time per step. The correlation between step stress data and life-test failures representing the main population is good. It is possible to use this quick test for lot acceptance and to design a proper voltage screening for the particular batch under test. The need for conventional burn-in testing would thus be reduced.