Enhanced p-MOSFET performance by channel field redistribution

We discuss how the performance of p-channel MOSFETs can be improved by introducing a variable threshold voltage along the conducting channel. The threshold voltage variation is designed to increase the charge carrier concentration near the drain, thereby increasing the saturation voltage and the saturation current, and improving the device speed. The effect was demonstrated experimentally by subjecting p-MOSFETs to high-bias stress, which creates a step-variation in the threshold voltage near drain. We also developed device models for p-MOSFETs with linearly variable threshold, and predict that more than 40% speed gain may be achieved in some cases.