It has been reported that dc test results may not be applicable to the prediction of device lifetime under ac stressing because ac stress can enhance the degradation rate over dc stress by up to an order of magnitude and thus reduce lifetime by up to two orders of magnitude. Comparative studies on the MOSFET degradation under ac and dc stresses are presented. They show that an excess substrate current during the trailing edge of the gate pulse may be responsible for the enhanced ac degradation. It is found that the ratio of ac and dc degradation rate is very sensitive to the specific waveforms used, which explains the diverse data reported in the literature.
|Number of pages||2|
|Journal||Digest of Technical Papers - Symposium on VLSI Technology|
|State||Published - 1 Dec 1987|