Tuned MEDICI simulator including inverse short channel effect for sub-0.18-μm CMOS technologies

This paper describes device simulation using a simulator (MEDICI) which is tuned to accurately predict the I-V characteristics of MOSFETS with conventional (non-pocket) channel profiles or pocket implants, and physical gate lengths from 10 micrometer to 0.16 micrometer. The key features of the simulation are, (1) the addition of a doping profile correction to the channel in NMOSFETs to model the inverse (reverse) short channel effect (ISCE/RSCE), (2) the incorporation of a new model to describe the pocket implant profile, and (3) the use of a two-step doping profile in the polysilicon gate to model gate depletion. The estimation of parameters for the profile correction and the pocket implant model, and the procedure of matching the simulated and experimental threshold voltage (V_T) as a function of gate length is described for the first time in this paper. The two- step gate doping profile, mobility parameters, external source-drain resistance R_sd and saturation velocity V_sat, used in the simulation, are determined by comparing the experimental and simulated C-V and I-V characteristics using the methodology discussed in reference 4. Good agreement between measured and simulated device characteristics is demonstrated for NMOS and PMOS devices with conventional profiles and pocket implants with varying doses, at supply voltages of 1 and 1.5 V.