Modeling of the CoolMOS/sup TM/ transistor - Part I: Device physics

CoolMOS/sup TM/ is a novel power MOSFET with a "superjunction" for its drift region, which results in a vastly improved relationship between the on resistance and breakdown voltage. The presence of the superjunction makes the device physics very interesting and complicated. In this paper, we present simulation results aimed at understanding the device operation both in the on state and in the off state. Quasi saturation of the drain current is analyzed, and it is shown that it can be prevented by increasing the doping density of the drift region. An analytic model of the JFET-like drift region is presented. A CoolMOS/sup TM/ transistor model based on the simulation results described here will be presented in an accompanying paper.