Optimization and Comparison of Drift Region Specific ON-Resistance for Vertical Power Hk MOSFETs and SJ MOSFETs With Identical Aspect Ratio

Abstract

This article proposes a MATLAB-based optimization methodology of the drift region specific ON-resistance ( ${R}_{on,sp}$ ) both for the high-permittivity ( $\text{H}{k}$ ) MOSFETs and superjunction (SJ) MOSFETs with design parameters expressed by breakdown voltage (BV) and aspect ratio (AR). The optimized method has three distinctive features. First, based on the built-in functions in MATLAB, the proposed method is very efficient to accurately obtain the optimized ${R}_{on,sp}$ ( ${R}_{on,sp(opt)}$ ) and the design parameters for both MOSFETs. Second, as the reflection of the process difficulty in the $\text{H}{k}$ or SJ structure, AR is used as one of the design variables. Third, the cubic polynomial functions are used to obtain a more accurate fitting for the optimization. The optimized results demonstrate that for a given BV, the ${R}_{on,sp(opt)}$ for the SJ MOSFET decreases as AR increases, whereas an optimum AR exists for a minimal ${R}_{on,sp(opt)}$ for the $\text{H}{k}$ MOSFET. Extensive comparisons demonstrate that when AR is small and BV is large, the ${R}_{on,sp(opt)}$ for the $\text{H}{k}$ MOSFET could be lower than that for the SJ MOSFET. Parameter designs are performed for the 900-V $\text{H}{k}$ MOSFET and SJ MOSFET. The impacts of important parameter variations on BV and ${R}_{on,sp}$ are also discussed. The validity of the proposed optimization method is demonstrated by the TCAD simulations.