LAUSR

An anomalous breakdown voltage (BV) walk-in phenomenon of the trench-gate p-type vertical double-diffused metal–oxide–semiconductor (VDMOS) after single avalanche stress has been experimentally investigated. It is found that the BV of the VDMOS is decreased after the single avalanche stress, while other electrical parameters remain unchanged. T-CAD simulations and emission microscope (EMMI) analysis have been carried out. As a result, the shift of the breakdown point of the VDMOS, which results in the hot hole injection and trapping at the termination region, should be responsible for the BV degradation. A novel device structure with different trench depths in the termination region for the trench-gate p-type VDMOS is proposed to suppress the BV walk-in phenomenon.