Detection and Diagnosis of Static Scan Cell Internal Defect

In this paper, we study the impact, detection and diagnosis of the defect inside a scan cell, which is called scan cell internal defect. We first use SPICE simulation to understand how a scan cell internal defect impacts the operation of a single scan cell. To study the detectability and diagnosability of a scan cell internal defect in a production test environment, we inject scan cell internal defects into a scan-based industrial design and perform fault simulation by using production scan test patterns. Next, we evaluate how effective an existing scan chain diagnosis technique based on traditional fault models can diagnose scan cell internal defect. We finally propose a new diagnosis algorithm to improve scan cell internal defect diagnostic resolution using scan cell internal fault model. Experimental results show the effectiveness of the proposed scan cell internal fault diagnosis technique.