Study on Conductivity Degradation of High-k VDMOS Caused by Ferroelectricity

The remanent polarization effect is considered for the simulation of Hk-VDMOS (high-k vertical double-diffused metal-oxide-semiconductor) for the first time. When the Hk- VDMOS is converted from off-state to on-state, a part of N-pillar near the Hk-pillar will be depleted due to the remanent polarization of the Hk insulator. Then, according to the simulation results for 300 V devices, the electron current channel will be severely narrowed and the conduction voltage drop will be increased by 30.4%. Hence, the ferroelectric effect significantly impairs the conductive ability of Hk- VDMOS, which leads to a decrease of the transfer efficiency in the power conversion system.