On the Efficacy of Scan Chain Grouping for Mitigating IR-Drop-Induced Test Data Corruption

Yucong ZHANG  Stefan HOLST  Xiaoqing WEN  Kohei MIYASE  Seiji KAJIHARA  Jun QIAN  

IEICE TRANSACTIONS on Information and Systems   Vol.E104-D   No.6   pp.816-827
Publication Date: 2021/06/01
Publicized: 2021/03/08
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2020EDP7042
Type of Manuscript: PAPER
Category: Dependable Computing
scan testing,  shift switching activity,  IR-drop,  shift failure,  partial-shift,  scan chain grouping,  local shift switching activity,  

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Loading test vectors and unloading test responses in shift mode during scan testing cause many scan flip-flops to switch simultaneously. The resulting shift switching activity around scan flip-flops can cause excessive local IR-drop that can change the states of some scan flip-flops, leading to test data corruption. A common approach solving this problem is partial-shift, in which multiple scan chains are formed and only one group of the scan chains is shifted at a time. However, previous methods based on this approach use random grouping, which may reduce global shift switching activity, but may not be optimized to reduce local shift switching activity, resulting in remaining high risk of test data corruption even when partial-shift is applied. This paper proposes novel algorithms (one optimal and one heuristic) to group scan chains, focusing on reducing local shift switching activity around scan flip-flops, thus reducing the risk of test data corruption. Experimental results on all large ITC'99 benchmark circuits demonstrate the effectiveness of the proposed optimal and heuristic algorithms as well as the scalability of the heuristic algorithm.