Model Overview

BSIM-CMG is a SPICE compact model for modeling the electrical characteristics of common gate MG structures, developed by UC Berkeley.

Physical surface potential-based formulations are derived for both intrinsic and extrinsic models with finite body doping. The surface potentials at the source and drain ends are solved analytically with poly-depletion and quantum mechanical effects. The effect of finite body doping is captured through a perturbation approach. The analytic surface potential solution agrees with 2-D device simulation results well. If the channel doping concentration is low enough to be neglected, computational efficiency can be further improved by setting COREMOD = 1.

All the important MG transistor behaviors are captured by this model. Volume inversion is included in the solution of the Poisson's equation, hence the subsequent I-V formulation automatically captures the volume inversion effect. Analysis of the electrostatic potential in the body of MG MOSFETs provided the model equation for the short channel effects (SCE). The extra electrostatic control from the end-gates (top/bottom gates) (triple or quadruple-gate) is also captured in the short channel model.

Users can specify the MG structure of interest via a geometry mode selector (GEOMOD, DG = 0, TG = 1, QG = 2, CG = 3). Hybrid-surface-orientation mobility, corner-induced effective width reduction, and end-channel-enhanced electrostatic control are considered to address the physics of tri-gate (TG) and quadruple-gate (QG) devices.

BSIM-CMG provides the flexibility to model devices with novel materials. This includes parameters for non-silicon channel devices and High-K/ Metal-gate stack.

Other important effects, such as, mobility degradation, velocity saturation, velocity overshoot, series resistance, channel length modulation, quantum mechanical effects, gate tunneling current, gate-induced-drain-leakage, temperature effects, channel thermal noise, flicker noise, noise associated with device parasitics, and parasitic capacitance, are also incorporated in the model.

BSIM-CMG has been verified with industrial experimental data. The model is continuous and symmetric at Vds = 0. This physics-based model is scalable and predictive over a wide range of device parameters.