Dependence of switching waveform on charge imbalance in superjunction MOSFET used in inductive load circuit

Abstract

The switching waveform of superjunction (SJ) Si-MOSFETs used in inductive load circuit was investigated. At the turn-off phase, a hump appears in the drain current. Both experiment and simulation indicated that the amplitude of the current hump drastically depends on the charge imbalance (CIB). On the other hand, at the turn-on phase, calculation showed that the dependence of di/dt on CIB is opposite in the cases of planar or trench gate structure. These changes of switching waveform are caused by the electrostatic potential distribution around the gate structure. Based on the analysis we propose non-sensitive to CIB device structures in this paper.