Investigation on marginal failure characteristics and related defects analysed by soft defect localization

Soft defect localization is a well established failure analysis technique for detecting defects causing integrated circuits to marginal fail. First simulations on Shmoo characteristics using a defect model on simple inverter logic have already been presented. However, the influence of a defect on the Shmoo characteristic for more complex circuit structures is not investigated.This paper discuss a correlation of Shmoo results to both, the defect type and failing circuit structure of a SRAM-cell. Soft defect localization has been applied on two examples showing a bridging defect with a SRAM-cell. In both cases the Shmoo characteristics show a strong voltage dependency. The effect of various bridging defects within a SRAM-cell has been simulated and discussed. With these results the Shmoo characteristic should be considered in the analysis for a defect based on soft defect localization.