Insulated gate-type semiconductor device having a low concentration diffusion region

摘要

A semiconductor 100 has a P− body region and an N− drift region in the order from an upper surface side thereof. A gate trench and a terminal trench passing through the P− body region are formed. The respective trenches are surrounded with P diffusion regions at the bottom thereof. The gate trench builds a gate electrode therein. A P−− diffusion region, which is in contact with the end portion in a lengthwise direction of the gate trench and is lower in concentration than the P− body region and the P diffusion region, is formed. The P−− diffusion region is depleted prior to the P diffusion region when the gate voltage is off. The P−− diffusion region serves as a hole supply path to the P diffusion region when the gate voltage is on.