Stuck-fault tests vs. actual defects

This paper studies some manufacturing test data collected for an experimental digital IC. Test results for a large variety of single-stuck fault based test sets are shown and compared with a number of test sets based on other fault models. The defects present in the chips studied are characterized based on the chip tester responses. The data presented shows that N-detect test sets are particularly effective for both timing and hard failures. In these test sets each single-stuck fault is detected by at least N different test patterns. We also present data on the use of IDDq tests and VLV (very low voltage) tests for detecting defects whose presence doesn't interfere with normal operation during manufacturing test, but which cause early life failure.