Stress induced leakage current under pulsed voltage stress

Abstract

Stress induced leakage current (SILC) is one of the main problems in ultra-thin oxide MOS devices before the onset of soft or hard breakdown. This paper addresses the problem of SILC produced by dynamic stress. We have studied the behaviour of ultra-thin oxides subjected to pulsed voltage stress (PVS) and the results have been compared with those obtained after constant voltage stress (CVS) and constant current stress (CCS). SILC has been studied as a function of PVS frequency: a decrease of low field leakage current has been found at high frequencies, pointing out to an enhanced life time of devices in integrated circuits operating at alternating voltage (as the majority of applications of silicon-based devices). The growth kinetics of SILC has been found to satisfy the same empirical model previously found for constant current stress. In the present work this model has been extended to PVS and the frequency dependence has been investigated.