Compact charge modeling of the double-gate MOS considering quantum confinement effect by using the density-gradient equation

Abstract

In order to increase the integration of the transistor, the size of the device has continuously decreased. Downscaling of conventional planar MOSFETs, however, faced physical limitations. Multi-gate FETs have been proposed as an alternative to overcome these limitations. In this context, the need for a study of a compact model of multi-gate FETs is revealed. The compact model is designed to simplify and represent semiconductor devices to be sufficiently effective circuit simulation elements. To build a compact model, a proper charge model must be established. In order to build such a charge model, geometric effects and quantum mechanical effects have to be considered. In the case of geometrical effect, equivalent DG MOSFET structure is concerned. Density-gradient equation is applied to consider quantum confinement effect. In this study, a compact charge model for double-gate MOSFETs with the quantum confinement effect by using density-gradient equation is presented. The coupled governing equations are rigorously integrated. There is no additional approximation in the process of the deriving coupled equation. Contribution of the density-gradient equation is clearly identified. Based on the resultant integrated equation, a compact charge model is proposed. Properly fitted parameters are required for this compact charge model to work well. Therefore, we also find fitting parameters for compact charge model by comparing TCAD results.