CMOS floating gate defect detection using I/sub DDQ/ test with DC power supply superposed by AC component

In this paper, we propose a new I/sub DDQ/ test method for detecting floating gate defects in CMOS ICs. In the method, an unusual increase of the supply current, caused by defects, is promoted by superposing an AC component on the DC power supply. The feasibility of the test is examined by some experiments on four DUTs with an intentionally caused defect. The results showed that our method could detect clearly all the defects, one of which may be detected by neither any functional logic test nor any conventional I/sub DDQ/ test.