Advanced Scan Chain Failure Analysis Using Laser Modulation Mapping and Continuous Wave Probing

Scan chain failures are a significant fraction of yield loss. The complexity of modern design-for-test (DFT) implementation techniques and more subtle failure mechanisms of sub-40nm technologies make defect identification more challenging. Software chain diagnosis and a variety of EFA techniques have been deployed to improve scan chain failure isolation. However, we have found in practice that each of these techniques has significant limitations.