Trench gate power MOSFETs with retrograde body profile

Abstract

Low specific on-resistance (R-ds,R-on) and low gate capacitance are essential for trench gate power MOSFETs. In this work, we propose a simple method of retrograde body profile to improve the two parameters simultaneously. The retrograde body MOSFET (RBMOS) is realized by high energy implantation. Because the highest channel concentration locates close to drain side, the depletion width at drain side is suppressed so that the channel length can be shortened greatly without sacrificing punch-through voltage. Low thermal budget and easy trench gate process are additional benefits. Power MOSFET with channel length of 0.4 mum, threshold voltage of 1V, and breakdown voltage of 32V is demonstrated. Comparing with the conventional device, the specific on-resistance and the figure-of-merit can be improved by 38% and 70%, respectively.