Patent ID: 7019379

Claim:
A semiconductor device comprising a voltage regulator element, wherein the voltage regulator element includes: a heavily doped layer of a second conductivity type which is formed in a semiconductor layer of a first conductivity type; an intermediately doped layer of the second conductivity type which is formed to adjoin and surround the heavily doped layer; and an isolation region which is formed to surround a region containing the heavily doped layer and the intermediately doped layer, the heavily doped layer of the second conductivity type has a higher dopant concentration than the semiconductor layer of the first conductivity type, the intermediately doped layer of the second conductivity type has a dopant concentration higher than the semiconductor layer of the first conductivity type and lower than the heavily doped layer of the second conductivity type, a region of the semiconductor layer surrounded with the isolation region, except under the isolation region, is formed with a lightly doped layer which covers the under surfaces of the heavily doped layer and the intermediately doped layer, and the lightly doped layer has a dopant concentration higher than the semiconductor layer of the first conductivity type and lower than the intermediately doped layer of the second conductivity type.