Model Overview

Physical surface-potential-based formulations are derived in both intrinsic and extrinsic models of BSIM-IMG. Surface potentials and integrated charge densities at the source and drain ends are obtained by solving the Poisson’s equation in a fully-depleted, lightly doped body and calculating with efficient analytical approximations. Since the surface potential equation is derived based on Poisson’s equation, the model captures volume inversion effects adequately and shows excellent scalability compared with 2D device simulation.

To meet the requirements of future devices, new parameters have been included to model devices consisting of novel materials. This includes parameters for non-silicon channel devices and High-K gate insulators.

The back-gate of a planar double-gate SOI FET is often used for tuning device threshold voltage (VTH). Therefore, the effect of back-gate on VTH must also be addressed by the model. VTH varies with back-gate voltage. When Vbg is low, they follow a linear relationship. At large Vbg, however, the back-gate effect slows down as a result of back surface accumulation.

Other important effects, such as short channel effects, mobility degradation, velocity saturation, velocity overshoot, series resistance, channel length modulation, quantum mechanical effects, gate tunneling current, gate-induced-drain-leakage, and parasitic capacitance are also incorporated in the model.

The model is continuous and symmetric at Vds=0. This physics-based model is scalable and predictive over a wide range of device parameters.