Compact dictionaries for fault diagnosis in BIST

Abstract

We present a new technique for generating compact dictionaries for cause-effect diagnosis in BIST. This approach relies on the use of three compact dictionaries: (i) D/sub 1/, containing compacted LFSR signatures for a small number of patterns and faults with high detection probability, (ii) an interval-based pass/fail dictionary D/sub 2/ for the BIST patterns and for faults with relatively lower detection probability, and (iii) D/sub 3/, containing compacted LFSR signatures for clean-up ATPG vectors and random-resistant faults. We show that D/sub 2/, which is two orders of magnitude smaller than a maximal-resolution pass/fail dictionary, provides nearly the same diagnostic resolution as an uncompacted dictionary. We also show that by using a 16-bit LFSR signature for D/sub 1/ and D/sub 2/, we obtain three orders of magnitude reduction in dictionary size, yet nearly no loss in diagnostic resolution.