Results and acceleration factors between several highly accelerated stress test (HAST) conditions and 85 degrees C/85% relative humidity tests are given for NMOS EPROMs (erasable programmable read-only memories) and CMOS RAMs (random-access memories). Two failure regimes exist in time: the earliest is below 25% cumulative failures and is due to passivation defects; beyond that, failures are due to passivation moisture saturation or wearout. Results are sensitive to device/process, passivation integrity, and test apparatus cleanliness. Failure predictions are dependent on which failure regime is used.
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