Patent ID: 6943410
Filing Date: 2005-09-13
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor chip; a low electrical resistance layer of a first conductivity type or a second conductivity type on a bottom portion of the semiconductor chip; a breakdown-voltage sustaining layer of the first conductivity type above the low electrical resistance layer; a well region of the second conductivity type in a surface portion of the breakdown-voltage sustaining layer; a source region of the first conductivity type in a surface portion of the well region, the source region being spaced apart from the breakdown-voltage sustaining layer by the well region; a gate electrode above a portion extending from the well region and adjoining the source region, with a gate insulation film interposed therebetween; and surface drain regions of the first conductivity type surrounded by the well region in the surface of the semiconductor chip, wherein the ratio between the total surface area of the surface drain regions surrounded by the well region and the surface area of the well region, including the source region, is from 0.01 to 0.2.