Patent ID: 8227314

Claim:
A semiconductor device manufacturing method comprising the steps of: forming a drift region by epitaxially growing a first conductivity type semiconductor layer on the main surface of a first conductivity type semiconductor base body; forming a gate insulating film on the drift layer surface; forming gate electrodes on the gate insulating film; ion-injecting a second conductivity type impurity using the gate electrodes as masks; forming second conductivity type body regions by thermally diffusing the ion-injected impurity; forming source regions in the main body transistor region and source regions and drain regions in the electrostatic discharge protection element region by ion-injecting a first conductivity type impurity into the body regions using the gate electrodes as masks; and forming body potential extraction regions by ion-injecting a second conductivity type impurity into the body regions, wherein in the process step for forming second conductivity type body regions, gate electrodes of the electrostatic discharge protection element are formed so that the gate length thereof is equal to or less than twice the diffusion length of the ion-injected impurity in the direction of the gate electrodes of the main body transistor.