Optimization of Specific on-Resistance of Semisuperjunction Trench MOSFETs with Charge Balance

Analytical models of the 2-D electric field distributions of the interdigitated balanced symmetric semisuperjunction (SemiSJ) structure, based on the charge superposition method, are derived. An accurate approximation of the exact analytical solution of the vertical electric field is also proposed and demonstrated by device simulation. The optimization method and its numerical calculation results of the specific on-resistance of the SemiSJ trench MOSFETs with constant aspect ratio (AR) are presented and verified by simulations. The calculation results show that the optimized specific on-resistance of SemiSJ trench MOSFETs can be reduced by more than 12% with AR equaling three, as compared with that of superjunction trench MOSFETs. The effect of charge imbalance on the breakdown voltage (BV) is also investigated. It is found that the maximum BV is achieved at high-Qpcondition rather than at charge-balance condition.