Hot-carrier-induced MOSFET degradation: AC versus DC stressing

摘要

Hot-carrier induced MOSi FT degradation is a serious concern to VLSI technology development. The substrate current has been shwon to be a good monitor of hot-carrier population and can be used to extrapolate the accelerated stressing results to normal-voltage lifetime. As illustrated in Fig. 1. lifetime projection under DC stressing conditions is thus well established. Fig, 1 includes data reported in the literature[1,2] as well as measurements performed in our laboratory. Not only is there a common slope (¿¿¿3) for devices from different sources, but the magnitude fall in a narrow range for most devices. A reasonable fit is lifetime ¿¿¿ 106 [ISUB/W]¿¿¿3. The lifetimes in Fig. 1 were defined at 10 mV shift of the threshold voltage VT. The degradation of drain current Id is also commonly used for lifetime definition. Fig. 2 shows that under DC stress, ¿¿VT=10 mV corresponds to ¿¿Id/Id=3 % for wide range of biases and device dimensions.