Evaluation of Miller Capacitance Depending on Drain-Source Voltage when SJ HV Power MOSFETs are in Reverse Mode

Abstract:
Miller capacitance, sometime called Crss, monotonic decreases increasing Vds. This model is surely confirmed when considering power MOSFETs realized in Planar technology. At any rate, when considering Super Junction devices and, in particular, newest High Voltage power MOSFETs, it was experimentally observed that Crss does not decrease monotonic by increasing Vds. In fact, in these last devices, Crss firstly decreases down to very low values and then monotonic increases up to reach a plateau region.This paper studies the above exposed phenomenon basing results either on TCAD simulations or on experimental data by introducing a simplified mathematical model which explains the empirical behavior of Crss in SJ power MOSFETs.