An improved power MOSFET using a novel split well structure

Abstract

The design trade-offs between the specific on-resistance (R/sub sp/), the ruggedness and the reverse recovery charge (Q/sub rr/) of the body-diode for vertical power MOSFETs has been significantly improved by using a novel split-well (SW) concept. The implementation of the SW structure is straightforward with low cost. It is expected that the source exclusion mask can be removed. When compared to a conventional VDMOST with the same design rules, the SW device provides 15% lower R/sub sp/ and 10% lower Q/sub rr/ without degradation of device ruggedness. In addition, it is expected that the SW device will yield higher hot-carrier reliability.