Abstract
Cell-aware test (CAT) explicitly targets defects inside library cells and therefore significantly reduces the number of test escapes compared to conventional automatic test pattern generation (ATPG) approaches that cover cell-internal defects only serendipitously. CAT consists of two steps, viz. (1) library characterization and (2) cell-aware ATPG. Defect detection matrices (DDMs) are used as the interface between both CAT steps; they record which cell-internal defects are detected by which cell-level test patterns. This paper proposes two algorithms that manipulate DDMs to optimize cell-aware ATPG results with respect to fault coverage, test pattern count, and compute time. Algorithm 1 identifies don't-care bits in cell patterns, such that the ATPG tool can exploit these during cell-to-chip expansion to increase fault coverage and reduce test-pattern count. Algorithm 2 selects, at cell level, a subset of preferential patterns that jointly provides maximal fault coverage at a minimized stimulus care-bit sum. To keep the ATPG compute time under control, we run cell-aware ATPG with the preferential patterns first, and a second ATPG run with the remaining patterns only if necessary. Selecting the preferential patterns maps onto a well-known N Phard problem, for which we derive an innovative heuristic that outperforms solutions in the literature. Experimental results on twelve circuits show average reductions of 43% of non-covered faults and 10% in chip-pattern count.
Original language | English |
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Title of host publication | Proceedings - 2019 IEEE International Test Conference in Asia, ITC-Asia 2019 |
Place of Publication | Piscataway |
Publisher | Institute of Electrical and Electronics Engineers |
Pages | 91-96 |
Number of pages | 6 |
ISBN (Electronic) | 978-1-7281-4718-5 |
DOIs | |
Publication status | Published - 1 Sep 2019 |
Event | 3rd IEEE International Test Conference in Asia, ITC-Asia 2019 - Tokyo, Japan Duration: 3 Sep 2019 → 5 Sep 2019 |
Conference
Conference | 3rd IEEE International Test Conference in Asia, ITC-Asia 2019 |
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Country | Japan |
City | Tokyo |
Period | 3/09/19 → 5/09/19 |
Keywords
- ATPG
- Cell Aware
- DDM
- Don't Care
- MinCover