The 2nd order analysis of IDDQ test data

The proposed 2^nd order current signature technique considers both the 1^st order mean and the 2^nd order variance information to provide a more robust and more effective means of die selection. We examined the I_DDQ testing data from SEMATECH by the proposed 2^nd order current signature technique and compared the results to those of traditional single threshold and delta I_DDQ techniques. We found that the 2^nd order analysis may enable a more robust way to implement I_DDQ testing. In particular, a clear distinction can be made between defected and defect-free dies. The defected dies identified by the proposed technique and by the delta-I_DDQ technique are quite similar for the SEMATECH data. However, for the future deep sub-micron VLSI where the mean I_DDQ value may vary significantly, the proposed technique has a definite advantage of being more robust