VERTICAL SEMICONDUCTOR DEVICE

摘要

The problem to be solved by the present invention is to improve the withstand voltage of the peripheral region 6 of the semiconductor device 2. A resurf layer 32 and a guard ring 30 are formed in a peripheral region 6 in a position at the surface of the semiconductor substrate. The guard ring 30 is formed more deeply than the resurf layer 32. When the guard ring 30 is shallow and the impurity concentration of the resurf layer 32 is low, the potential distribution at the deep portion of the resurf layer 32 becomes unstable, and the resurf layer 32 does not sufficiently exhibit the effect of improving the withstand voltage. When the guard ring 30 is deep, the impurity concentration of the guard ring 30 is high, the potential distribution at the deep portion of the resurf layer 32 is regulated by the guard ring and the resurf layer 32 sufficiently exhibits the effect of improving the withstand voltage.