Test Considerations for Gate Oxide Shorts in CMOS ICs

Gate oxide shorts are defects that must be detected to produce high-reliability ICs. These problems will continue as devices are scaled down and oxide thicknesses are reduced to the 100-Å range. Complete detection of gate oxide shorts and other CMOS failure mechanisms requires measuring the IDD current during the quiescent state after each test vector is applied to the IC. A 100-percent stuck-at fault test set is effective only if each test vector is accompanied by an IDD measurement. This article examines the need for a fast, sensitive method of measuring IDD during each test vector and discusses problems confronting CMOS IC designers, test engineers and test instrumentation designers as they work to meet these demands.