Reliability characterization of LSI memories

The primary objective of this effort was to evaluate and characterize the reliability and failure modes of 4K Large Scale Integration (LSI) memories procured to the specification requirements of MIL-M-38510/237. Secondary objectives were to evaluate the screening effectiveness of the detail specifications and to compare the relative effectiveness of high temperature accelerated life tests performed with both static and dynamic excitation. The program objectives were achieved by subjecting the test devices to a matrix of temperature cycling tests, high temperature non-operating life tests, and high temperature operating life tests with static and dynamic excitation. The part types under evaluation include a 1K x 4 bit NMOS static RAM (AM9130) and a 4K x 1 bit NMOS static RAM (AM9140). The test results indicated that the AM9130 and AM9140 devices have a high reliability potential. However, there was an insufficient number of life test failures to estimate the device failure rates based on the Arrhenius Reaction Rate Model. A total of eighteen devices of 240 total tested were failed at the completion of testing and all but two failures were attributed to a surface related mechanism(s). Seven of the eighteen device failures were due to marginal I(CC) values at the start of life testing and a single failure was attributed to a degraded input caused by static discharge or an electrical transient.