Short-channel effect improved by lateral channel-engineering in deep-submicronmeter MOSFET's

Abstract

The normal and reverse short-channel effect of LDD MOSFET's with lateral channel-engineering (pocket or halo implant) has been investigated. An analytical model is developed which can predict V/sub th/ as a function of L/sub eff/, V/sub DS/, V/sub BS/, and pocket parameters down to 0.1-/spl mu/m channel length. The new model shows that the V/sub th/ roll-up component due to pocket implant has an exponential dependence on channel length and is determined roughly by (N/sub p/)/sup 1/4 /L/sub p/. The validity of the model is verified by both experimental data and two-dimensional (2-D) numerical simulation. On the basis of the model, a methodology to optimize the minimum channel length L/sub min/ is presented. The theoretical optimal pocket implant performance is to achieve an L/sub min/ approximately 55/spl sim/60% that of a uniform-channel MOSFET without pocket implant, which is a significant (over one technology generation) improvement. The process design window of pocket implant is analyzed. The design tradeoff between the improvement of short-channel immunity and the other device electrical performance is also discussed.