On comparison of NCR effectiveness with a reduced I/sub DDQ/ vector set

I/sub DDQ/ test-based outlier rejection becomes difficult for deep sub-micron technology chips due to increased leakage and process variations. The use of neighbor current ratio (NCR) that uses wafer-level spatial correlation for identifying outlier chips has been proposed earlier as a means of coping with these issues. Due to the slow speed of I/sub DDQ/ test, there is a strong motivation to reduce the number of test vectors without compromising the fault coverage. In this paper, we examine the effectiveness of neighbor current ratio using a reduced I/sub DDQ/ vector set and industrial test data.