Modeling of a standard 0.35 μm CMOS technology operating from 77 K to 300 K

An improved simulation model for the static characteristics of MOSFETs operating at cryogenic temperatures is presented. Due to the freeze-out effects, standard BSIM model cannot fit well for characteristic of MOSFET at cryogenic temperatures. The advanced models incorporating the effects in cooled MOSFET are required for the simulation of mixed analog-digital circuits operating at low temperatures. In this paper, the critical parameters of the BSIM model are extracted from 77 K to 300 K, and the temperature-dependent parameter functions are built to improve fitting precision at different low temperatures. Meanwhile, the freeze-out effect in lightly doped drain (LDD) region at 77 K is described and modeled. This study is performed on a standard CMOS technology with 0.35 μm/3.3 V MOSFET. Some improvements of the proposed model will allow a precise description of MOS transistors for design of cryogenic circuits.