Plasma-induced polarity dependent hot-carrier response of CMOS devices across a wafer

Abstract

In this study, plasma-processed devices are subjected to hot-carrier stressing experiments to evaluate the reliability across the wafer. Devices with N/sup +/-P, P/sup +/-N, both N/sup +/-P and P/sup +/-N diodes, and no protection diode, are used to establish the nature of the injection (gate and substrate) conditions across the wafer. Results show that P-channel devices subjected to gate injection during plasma processing show higher degradation than those subjected to substrate injection. N-MOSFETs subjected to gate injection during plasma processing show a higher antenna ratio dependence than those subjected to substrate injection. Also, a linear relationship is observed between the pre-stress trapped positive charge in the oxide and threshold voltage shift after hot-carrier stress. Gate injection during plasma processes creates higher trapped positive charge and hence the hot-carrier lifetime of devices subjected to gate injection can be significantly lower than that of devices subjected to substrate injection.