Patent ID: 7986003
Filing Date: 2011-07-26
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor substrate of a first conductivity type having a first main surface and a second main surface opposite to each other; a first impurity region of the first conductivity type formed by a first impurity of the first conductivity type having a maximum impurity concentration at a first depth from said first main surface of said semiconductor substrate, said first impurity region formed in a region corresponding to said first depth and spaced from said first main surface; a second impurity region of a second conductivity type formed by a second impurity of the second conductivity type having a maximum impurity concentration at a second depth shallower than said first depth from said first main surface of said semiconductor substrate, said second impurity region formed from a region corresponding to said second depth to reach said first impurity region; a third impurity region of the first conductivity type formed by a third impurity of the first conductivity type having a maximum impurity concentration at said first main surface of said semiconductor substrate, said third impurity region formed from said first main surface to a predetermined depth and spaced from said first impurity region with said second impurity region therebetween; an opening extending through said third impurity region, said second impurity region and said first impurity region to reach a region of said first conductivity type of said semiconductor substrate; an insulating film formed on a sidewall of said opening to cover said third impurity region, said second impurity region and said first impurity region exposed on said sidewall; an electrode portion formed in said opening to cover said insulating film; and a region of the second conductivity type formed at said second main surface of said semiconductor substrate, wherein a combined impurity concentration profile of said first impurity and said second impurity has a first relative maximum value and a second relative maximum value corresponding respectively to respective impurity concentrations of said first impurity and said second impurity, said first relative maximum value is located in a concentration profile of said first impurity extending from the maximum impurity concentration of said first impurity to one-tenth of the maximum impurity concentration in a direction of depth from the first main surface to the second main surface, and said second relative maximum value is located in a concentration profile of said second impurity extending from the maximum impurity concentration of said second impurity to one-tenth of the maximum impurity concentration in the direction of depth from the first main surface to the second main surface.