Inverse modeling of sub-100 nm MOSFETs using I-V and C-V

Direct quantitative two-dimensional (2-D) profile characterization of state-of-the-art MOSFETs continues to be elusive. In this paper, we present a comprehensive indirect methodology that achieves that for sub-100 nm MOSFETs using combined current-voltage (I-V) and capacitance-voltage (C-V) data. An optimization loop minimizes the error between simulated and measured electrical characteristics by adjusting parameterized doping profiles. This technique possesses high sensitivity to critical 2-D doping in the source/drain extensions and channel region as well as to structural details such as t(ox) and physical gate length. Here we demonstrate the technique by characterizing two NMOS families (t(ox) = 3.3 nm and 1.5 nm with effective channel lengths down to 50 nm). We then follow up with an evaluation of the ability of inverse modeling to capture modern profiles using simulated devices and I-V data. We show that extracted profiles exhibit decreased root mean square error (RMSE) as the doping parameterization becomes increasingly comprehensive of doping features (i.e., implants or doping pile-up).