Segment based X-Filling for low power and high defect coverage

Many X-Filling strategies are proposed to reduce test power during scan based testing. Because their main motivation is to reduce the switching activities of test patterns in the test process, some of them are prone to reduce the test ability of test patterns, which may lead to low defect coverage. In this paper, we propose a segment based X-filling(SBF) technique to reduce test power using multiple scan chains, with minimal impact on defect coverage. Different from the previous filling methods, our X-filling technique is segment based and defect coverage aware. The method can be easily incorporated into traditional ATPG flow to keep capture power below a certain limit and keep the defect coverage at a high level.