Evaluating the Effectiveness of Physically-Aware N-Detect Test using Real Silicon

Physically-aware N-detect attempts to improve the detection characteristics of traditional N-detect by exploiting the localized characteristics of defects. Specifically, in addition to detecting each fault N times, we also require that the physical neighborhood surrounding the target change state as well. In this work, the effectiveness of the physically-aware metric is examined using two approaches. First, tester responses from an in-production IBM chip are analyzed to compare the physically-aware N-detect test with other traditional tests that include stuck-at, IDDQ, logic BIST, and delay tests. Second, diagnostic results from LSI chip failures are utilized to directly compare the traditional and physically-aware N-detect metrics. Results from both experiments demonstrate the effectiveness of physically-aware N-detect test in detecting defects in modern industrial designs.