Improvement of n-channel metal-oxide-semiconductor transistors by tensile stress despite increase in both on and subthreshold off currents.

We found that tensile stress actually increases both the on current and the subthreshold off current for n-channel metal-oxide-semiconductor transistors because of an increase in mobility. Our theory is that stress engineering works because the increase in the subthreshold off current can be easily offset by a slight increase in the saturation threshold voltage, while the increase in the on current can be offset only by a much larger increase in the saturation threshold voltage. In this paper, experimental variation in the saturation threshold voltage is achieved by the statistical variation in gate length and short-channel effect. Thus, the overall effect is an improvement. [ABSTRACT FROM AUTHOR]