A Lateral Power p-Channel Trench MOSFET Improved by Variation Vertical Doping

Abstract

An improved lateral power p-channel trench metal–oxide–semiconductor field-effect transistor (MOSFET) is proposed. By using a technique of variation vertical doping (VVD), the threat of charge imbalance posted by the parasitic trench capacitance is eliminated. Moreover, a p-type VVD increases the number of carriers, and an n-type VVD intensifies the charge compensation effect. Hence, compared to the conventional device without VVD, the proposed device gets a significantly improved tradeoff relationship between the breakdown voltage (BV) and the specific ON-resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON},SP}$ ). According to the simulation results, the proposed device using the triple piecewise VVD obtains a ${R}_{ \mathrm{\scriptscriptstyle ON},SP}$ of 10.6 $\text{m}\Omega \cdot $ cm2 at a BV of 440 V, reaching a figure of merit (FOM = BV2/ ${R}_{ \mathrm{\scriptscriptstyle ON},SP}$ ) being 2.4 times larger than that of the prior art.