Patent ID: 7906808
Filing Date: 2011-03-15
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor layer of a first conductivity type; a deep well of a second conductivity type formed in a portion of an upper layer portion of the semiconductor layer; a well of the first conductivity type formed in a portion of an upper layer portion of the deep well; a source layer of the second conductivity type formed in the well; a drain layer of the second conductivity type formed in the well apart from the source layer, wherein the drain layer is applied a driving voltage between the source layer and the drain layer, and electrically connects to the deep well via the well; a contact layer of the second conductivity type formed outside the well in an upper layer portion of the deep well and connected to the drain layer; a gate electrode provided in a region directly above a region between the source layer and the drain layer; a gate insulation film provided between the well and the gate electrode; and a drift layer of the second conductivity type formed in an upper layer portion of the well between the drain layer and a region directly below the gate electrode, wherein the drift layer has an effective impurity dose amount lower than an effective impurity dose amount of the drain layer.