CRITICAL OPERATION MARGIN TEST FOR LSI RELIABILITY ASSESSMENT.

In large scale ICs (LSI) there exist, with certain probability, some circuit elements whose electrical parameters are shifted far from the design target. Some of these anomalous initial parameter shifts, as well as drifts during operation, which impair reliability of the LSI, cannot be detected by conventional test methods because of randomness of occurence. A new test method, called Critical Operation Margin Test, has been developed for detection of this anomaly. The Critical Operation Margin is defined as the allowance of the external condition which is permitted for LSI correct operation.