A Novel Symbolic Simulation for Scan Chain Diagnosis

Locating the scan chain faults is very important for dedicated IC manufacturers to guide the failure analysis process for yield improvement. In this paper, we propose a new symbolic simulation for scan chain diagnosis to solve the diagnosis resolution problem. The proposed symbolic simulation, called the SFsimulation, is able to analyze the effects caused by faulty scan cells in good scan chains. Therefore, for scan chain diagnosis, we use the faulty information in good scan chains which are not contaminated by the faults while unloading scan out responses. The SF-simulation can tighten the size of the candidate list and achieve a high diagnosis resolution by analyzing fault effects of good scan chains, which are ignored by most previous works. Experimental results demonstrate the effectiveness of the proposed method.