Scan Chain Diagnosis-Driven Test Response Compactor

Diagnosis becomes a much more prevalent factor in the successful fabrication process of a design. In order to keep up with continuously shrinking technology nodes, compression along with compaction techniques became a standard methodology allowing to control the cost of test. Typically compaction techniques focus on detectability thus maintaining high quality of test, but neglect or, in many cases, ignore their impact on diagnosis. This paper presents a compactor which allows significantly improving chain diagnosis resolution while maintaining high quality standards from detectability point of view and having virtually no impact on test time and logic diagnosis. The paper presents the X-press compactor which is driven in a way allowing to maximize diagnostic ability of chain failures. Specifically, the number of physical failure analysis-ready cases increased up to two times. The feasibility and efficiency of the proposed solution is confirmed by a number of experimental results performed for industrial designs, including actual chain diagnosis.