An experimental evaluation of the differential BICS for I/sub DDQ/ testing

In this paper we present an experimental study on the effectiveness of I/sub DDQ/ testing using the differential built-in current sensor (BICS) circuit. Two new test chips were designed and fabricated implementing a CMOS version of the 74181 ALU chip. In copies of this circuit we included the capability of activating 45 different "realistic" CMOS faults: inter- and intra-layer shorts and opens. We examine the fault coverage of the differential BICS for these realistic faults. A significant finding of our study is that I/sub DDQ/ testing has the potential to detect several classes of "opens". Moreover, these include precisely those open faults for which two pattern voltage tests can get invalidated because of transient switching states.