Dependences of Short-Channel Effect on Doping Profiles for Nanoscale Metal–Oxide–Semiconductor Field-Effect Transistor

Abstract

The analytical dependences of the short-channel effect on the channel and source/drain doping profiles are presented for currently nanoscale metal–oxide–semiconductor field-effect transistor (MOSFET). The scale-length approach is used for determining the channel potential from two-dimensional Poisson's equation and the effective-doping model is applied for attaining short-channel effect from the potential solutions. The exponential dependences of threshold voltage roll-off on channel length can be retained for all kinds of doping profiles. However, the retrograde channel improves the short-channel effect by reducing its scale-length. The ultra-shallow junction relieves the threshold voltage roll-off by having a smaller coefficient for the exponential term. The effects of laterally nonuniform profiles for short-channel effect can be clarified by their effective scale-lengths. The halo doped channel provides a smaller effective scale-length to counteract short-channel effect, while the graded junction plays an opposite role to the halo doping with an enlarged effective scale-length. Without any fitting factors, excellent agreements between the numerical results and these models are obtained for wide ranges of device technologies into nanoscale regime.