An histogram based procedure for current testing of active defects

The purpose of this paper is to propose a new histogram-based differential current testing procedure of active defects. This procedure contains three steps: Preanalysis, Failure Analysis, and Production Testing. The main objectives of the Pre-analysis are to provide information on the most frequent active current defects and to help setting the limits between faulty and fault-free devices; these limits are then investigated during the Failure Analysis step in order to set the threshold between faulty and fault-free ICs. During the Production Testing step, this threshold is compared to the highest peak value appearing in a histogram built for each tested IC. Some selected results are presented, which confirm the test quality gain increase by using differential I_DDQ instead of I_DDQ itself as well as the additional reduction of bad test decision that can be obtained by a wise selection of test vectors reducing the vector-to-vector current variations