Eigen-signatures for regularity-based IDDQ testing

Researchers and test engineers challenge I/sub DDQ/ testing on deep submicron (DSM) devices. We have proposed to test devices with high I/sub DDQ/ currents at normal operating conditions based on exploiting the regularity of defect-free I/sub DDQ/ signatures, the I/sub DDQ/ responses of a circuit on a test vector set. This paper demonstrates the fundamental characteristics of the regularity and proposes a new methodology based on eigen-signatures. Eigen-signatures are unique signatures transformed from I/sub DDQ/ signatures. The analysis of five eigen-signatures, including enhanced "Delta I/sub DDQ/" and "Current Ratios," on a product indicates that: the I/sub DDQ/ values related to a test vector set have a small variation, whereas, the I/sub DDQ/ magnitudes have a large variation; and the defect current prediction error of methods focusing the changes between the test vectors is 23 times smaller than the error of methods focusing the I/sub DDQ/ magnitudes.