Patent ID: 7851854

Claim:
A SiC semiconductor device having an accumulation type MOSFET comprising: a substrate having a first conductive type and made of SiC; a drift layer having the first conductive type and made of SiC, wherein the drift layer is disposed on the substrate, and has an impurity concentration lower than an impurity concentration of the substrate; a trench disposed on a surface of the drift layer; a base region having a second conductive type and made of SiC, wherein the base region is disposed in a surface portion of the drift layer, and sandwiches the trench; a channel having the first conductive type and made of SiC, wherein the channel is disposed between the base region and a sidewall of the trench; a source region having the first conductive type and made of SiC, wherein the source region is disposed in a surface portion of the base region, and sandwiches the trench via the channel; a gate insulation film disposed on an inner wall of the trench; a gate electrode disposed in the trench via the gate insulation film; a source electrode electrically coupled with the source region; a drain electrode disposed on the substrate opposite to the drift layer; and a bottom layer having the second conductive type and made of SiC, wherein the bottom layer is disposed under the trench, wherein the MOSFET flows current between the source electrode and the drain electrode via the source region, the channel and the drift layer by controlling a voltage to be applied to the gate electrode, wherein the bottom layer includes an edge portion and a center portion, wherein the edge portion of the bottom layer is disposed under a corner of a bottom of the trench, and the center portion of the bottom layer is disposed under a center portion of the bottom of the trench, and wherein the edge portion of the bottom layer is deeper than the center portion of the bottom layer.