Unified submicrometer SOI/MOSFET model for circuit simulation

Abstract

As a result of significant advances in submicrometer thin film SOI/MOSFET technology over the last few years, SOI circuit design and simulation are becoming increasingly important in VLSI technology research. Consequently, a need for accurate and efficient SOI device models with a strong physical basis, for use in circuit simulators such as SPICE, has emerged. Up to now, several analytical SOI MOSFET models have been developed. However, these models still need improvements in several areas. Here, we describe a new physics based SOI MOSFET model which emphasizes the use of continual and analytical expressions in all regimes of operation, in order to assure efficiency and good convergence in circuit simulations. To this end, a theory based on the unified charge control model (UCCM) was used for describing the above- and below-threshold regimes with one single expression. Also, continuity in current, output conductance and its derivative are assured at the transition between the linear and the saturation regimes of operation. In addition, the model includes important effects related to short channel and thin film phenomena, to parasitic resistances, and to impact ionization near the drain.