More Effective Test: Slack-Based Transition Delay

How to achieve higher defect coverage than standard transition delay testing can provide.

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Semiconductor companies have come to rely on delay testing to attain high defect coverage of manufactured digital integrated circuits (ICs). Delay testing uses transition delay (TD) patterns created by automatic test pattern generation (ATPG) tools to target subtle manufacturing defects in fabricated designs. Although standard TD testing improves defect coverage beyond levels stuck-at patterns alone can achieve, the methodology is limited in its ability to reach the test quality levels required for the latest generation of nanometer designs. In response, an improved delay test methodology, slack-based transition delay (SBTD) testing, is being deployed by Synopsys customers as a means to achieve even higher defect coverage than standard TD testing.

This white paper describes the basic principles related to SBTD testing, which is available in Synopsys’ synthesis-based test solution, DFTMAX and TetraMAX ATPG. It begins by observing how TetraMAX is uniquely able to perform efficient slack-based ATPG, and then highlight the differences between SBTD ATPG and its ubiquitous predecessor, TD ATPG. Next, it explores the key quality-versus-cost tradeoffs and test effectiveness.

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