NodeRank: Observation-Point Insertion for Fault Localization in Monolithic 3D ICs

Monolithic 3D (M3D) ICs have emerged as a promising technology with significant improvement in power, performance, and area (PPA) over conventional 3D-stacked ICs. However, the sequential assembly of M3D tiers and immature fabrication process are prone to manufacturing defects and intertier process variations. Tier-level fault localization is therefore essential for yield ramp-up and diagnosis. Due to overhead concerns, only a limited number of observation points (OPs) can be inserted on the outgoing inter-layer vias (ILVs) of a tier to enable fault localization. We propose the computationally efficient NodeRank algorithm for observation-point insertion (OPI) on a small subset of outgoing ILVs. An ATPG-independent heuristic is presented, which is several orders-of-magnitude faster than ATPG fault simulation-based OPI. We introduce a metric called degree of fault localization to quantify the effectiveness of OPs. Evaluation results for two-tier M3D benchmark circuits show the effectiveness of the proposed method.