Studies of the SEMATECH IDDq test data

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In the first part of this paper, we studied a few variations of a current signature method on the SEMATECH test data. We discovered two important facts: (1) many troublesome IDDq behaviors in the present and future technology were found in the SEMATECH data, (2) for those troublesome data, a relation was observed between the mean and the variance of the test data. Based on these findings, we proposed the second order current signature technique which considers both the first order mean and the second order variance information to provide a more robust and more effective mean of die selection. We examined the IDDq testing data from SEMATECH by the proposed second order current signature technique and compared the results to those of traditional single threshold and delta-IDDq techniques. We found that the proposed second order analysis may enable a more robust way to IDDq testing. In particular, the proposed method correctly identified all 12 known bad dies, while the delta-IDDq allows five of them to pass. © 2002 Elsevier Science B.V. All rights reserved.

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Journal of Systems Architecture