Patent ID: 8604522

Claim:
A field effect type semiconductor device comprising: a well region of a second conductivity type with a source region of a first conductivity type and a drain region of the first conductivity type selectively formed in a surface of the well region; a control electrode configured to control a current path between the source region and the drain region; a first main electrode connected to the source region; and a second main electrode connected to the drain region, with respect to a reference defined as a position of the well region at an identical depth to a portion of the source region with maximum curvature or a portion of the drain region with maximum curvature, a profile of impurity concentration distribution of an impurity of the second conductivity type along a depth direction of the well region below the control electrode and between the source region and the drain region having a peak impurity concentration located within a range of depth positions of the well region extending from 0.15 micrometers above the reference to 0.15 micrometers below the reference.