Patent ID: 8735997
Filing Date: 2014-05-27
Classification: H01L

Abstract:
1. A semiconductor device comprising: a gate insulation film disposed on and physically in contact with a semiconductor layer of a first general conductivity type; a gate electrode disposed on the gate insulation film; a source layer of a second general conductivity type formed in a first surface portion of the semiconductor layer; a high impurity concentration drain layer of the second general conductivity type formed in a second surface portion of the semiconductor layer so as to be separated from a drain-side end of the gate electrode; an impurity layer of the first general conductivity type formed in a third surface portion of the semiconductor layer between the gate electrode and the high impurity concentration drain layer; and an intermediate impurity concentration drain layer formed in a fourth surface portion of the semiconductor layer so as to be disposed under the high impurity concentration drain layer and the impurity layer, the intermediate impurity concentration drain layer being lower in impurity concentration and deeper in depth than the high impurity concentration drain layer; a drain electrode disposed on the high impurity concentration drain layer so as to be physically in contact with the high impurity concentration drain layer; and a low impurity concentration drain layer of the second general conductivity type formed in a fifth surface portion of the semiconductor layer so as to be under the gate electrode and adjacent the impurity layer, wherein the impurity layer is physically in contact with the intermediate impurity concentration drain layer, the semiconductor layer is physically in contact with the intermediate impurity concentration drain layer, the impurity layer is not physically in contact with the drain electrode, the low impurity concentration drain layer is lower in impurity concentration and deeper in depth than the high impurity concentration drain layer and is lower in impurity concentration and shallower in depth than the intermediate impurity concentration drain layer, and the impurity layer does not extend underneath the gate electrode.