Precise Defect Localization of Scan Logic Failures by Thermal Laser Stimulation (TLS)

Scan design in modern advanced ICs has enabled the software-based fault diagnosis. It is a powerful tool for localization of defects. However, according to fault diagnosis, there are sometimes many defect candidates and each defect candidate can have many equivalent nets. These nets may be distributed widely, even over the whole chip. Therefore, an additional method of precise defect localization is needed as a complement. In this paper, the TLS method (Thermal Laser Stimulation) is utilized with a simplified setup for this purpose. It shows that the correlation between TLS inspection and scan diagnosis significantly saves analysis time due to the improvement of localization accuracy of the corresponding physical defect.