Modeling of inversion and centroid charges of long channel strained-silicon surrounding gate mosfets incorporating quantum effects

Abstract

This paper presents a modeling approach for strained silicon surrounding gate MOSFETs. The main contribution of this work is the simplification of the charge model by using an explicit solution technique which includes the strained and quantum effects. Quantum effects are essential due to extreme scaling of radius and oxide thickness. These can be solved by integrating the quantum capacitance and threshold in the proposed model. The gate capacitance is formulated based on a centroid charge that can be applied for multiple doping levels and structural dimensions. Meanwhile, the quantum effect on the channel due to carrier confinement can be approximated based on the radius of the channel. For the simulator, the Bohm Quantum Model (BQP) is used to facilitate the quantum effect. Our explicit model is in good agreement with the numerical simulator, for various gate voltages, doping concentration and structural effects, based on the centroid and inversion charge. It is found that the doping level can contribute to the changes in the centroid charge position from the silicon-oxide interface to the center of the channel. In addition, the tensile strain shows a significant impact on the electrical properties of the strained silicon surrounding gate such as threshold voltage, inversion charge, and current. This technique holds the potential for implementation is owing to advantages such as fast data computing which can be directly integrated into the circuit simulator.