The VDMOS safe area has been given and second breakdown phenomenon has been analyzed.The way how to avoid the second breakdown phenomenon has been discussed.

• 其中在功率器件的可靠性分析中给出了VDMOS的安全工作区,详细分析了VDMOS的二次击穿现象,提出了避免二次击穿现象发生的方法。