P-backtracking: A new scan chain diagnosis method with probability

Abstract

Scan chain architecture is a common and major DFT for SoCs. Scan chains must be flawless for reliable SoC test. If there is a fault in a scan chain, eliminating the fault and its cause is important for high yield of SoC. In this paper, a new scan chain diagnosis method, "p-backtracking", is proposed. This method uses only software to backtrack the logic circuit and calculates the probability of fault in scan chain. The experimental results using ISCAS'89 benchmark circuits show that p-backtracking can find single fault location with higher diagnosis accuracy and smaller diagnosis resolution compared to the conventional diagnosis methods.