High-k MOSFET performance degradation by plasma process-induced charging damage — Impacts on device parameter variation

We discuss plasma charging damage (PCD) to high-k gate dielectrics, in particular, the threshold voltage shift (ΔV_th) in metal-oxide-semiconductor field-effect transistors (MOSFETs). The PCD induced by the antenna effect is focused on, and ΔV_th and its variation are estimated for MOSFETs treated by various plasma processes. The direction of threshold voltage shift in damaged high-k MOSFETs was found to depend on the amount of damage, i.e., the polarity itself results in "negative" or "positive" as the charging damage varies. We demonstrate a model prediction based on both the power-law dependence of ΔV_th on the antenna ratio r (= exposed metal interconnect area/gate area) and the r distribution deduced from an interconnect-length distribution function (ILDF) in a large-scale integrated (LSI) circuit. Then, we simulate the variation in ΔV_th [σ(ΔV_th)]. PCD to high-k dielectrics may lead to a considerable contribution to MOSFET-parameter fluctuations.