An evaluation of defect-oriented test: WELL-controlled low voltage test

This paper presents an evaluation of defect-oriented test that targets bridging defects or leakage defects in the deep sub-micron process. As the power supply voltage or the threshold voltage (Vt) decreases, the detection of these defects becomes more difficult. Therefore the effectiveness of each test method should be clarified. In this paper we newly propose the WELL-controlled low voltage (WLV) test, which is a low-voltage test with substrate back biasing, and prove that it detects the defects that are not detected by the IDDQ test. The effectiveness of the WLV test for a small gate-width circuit is also discussed for a noisy environment when the very-low-voltage (VLV) test is inapplicable