A Runtime Efficient Graph-Based Cell-Aware Model Generation for Structural SRAM Testing

Testing advanced memories is essential for ensuring modern System-on-Chip quality. As transistor size continues to shrink, the probability of the occurrence of manufacturing defects increases, making conventional functional testing of SRAMs inadequate for achieving required Defect Parts per Million (DPPM). To address this issue, a novel structural testing approach using the Cell-Aware (CA) test methodology has been proposed in [1]. With this methodology, structural test patterns are obtained through an Automatic Test Pattern Generator (ATPG) by exploiting analog CA models (i.e., based on exhaustive analog simulations) for SRAM primary blocks. However, the generation of CA models through analog simulations is time-consuming and technology dependent. A methodology, namely TrUnDeL proposed in [2], is used to accelerate the CA model generation, combining a switch-level graph-based solution and analog simulations. In this work, we propose an adaptation of TrUnDeL to generate the CA models, using only the switch-level graph-based simulations. TrUnDeL CA models are then used by the ATPG to generate structural test patterns. Through a validation flow, we demonstrate that the aforementioned patterns, generated without running any analog simulations, achieve nearly the same fault coverage as the test patterns generated using exhaustive analog simulations on an SRAM case study. The time required to generate CA models is drastically reduced with TrUnDeL, from 1 hour to 15 seconds for the considered case study.