Fault diagnosis in designs with extreme low pin test data compressors

Diagnosis plays an important role to ramp up yield during IC manufacturing process. Limited observability due to test response compaction negatively affects diagnosis procedure. With modern compressors - targeting very high test data compression, diagnosis becomes even more complicated. In this paper, a complete diagnosis methodology focussing on a novel mapping algorithm has been described. The mapping algorithm maps failures from compressor pins to scan cells with great accuracy (even in presence of X-bits in the responses), so that, scan diagnosis can be used to find out the actual defects. Experimental results on industrial designs showed that the proposed method almost match scan based fault diagnosis results.