Modeling the effects of plasma-induced physical damage on subthreshold leakage current in scaled MOSFETs

This paper presents the impacts of plasma-induced damage on an off-state leakage current increase in scaled MOSFETs. Si recess structure in the source/drain extension region formed by high-energy ion bombardment is focused on. In addition to the effect of gate length shrinkage on subthreshold leakage current (Ioff) increase discussed so far, plasma-induced damage (PID) is found to increase Ioff drastically, in particular, for the MOSFET with a gate length shorter than 65 nm. Technology CAD simulations were performed to verify the effect. Since the recess depth is modeled by an analytical expression with the energy of ion from plasma on the basis of a modified range theory, the increase in Ioff can be estimated from plasma process condition. A scenario for significant enhancement in the statistical Ioff-distribution by PID is also discussed.