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

This article proposes a MATLAB-based optimization methodology of the drift region specific ON-resistance (R_on,sp) both for the high-permittivity (Hk) 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 Hk 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 Hk MOSFET. Extensive comparisons demonstrate that when AR is small and BV is large, the R_on,sp(opt) for the HkMOSFET could be lower than that for the SJ MOSFET. Parameter designs are performed for the 900-V Hk 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.