Patent ID: 7135752
Filing Date: 2006-11-14
Classification: H01L

Abstract:
1. A dielectric isolation type semiconductor device comprising: a semiconductor substrate having a principal plane and a rear surface disposed on opposite sides thereof; a main dielectric layer disposed adjacent to an entire area of the principal plane of said semiconductor substrate; a first semiconductor layer of a first conductive type of a low impurity concentration having a front surface and being bonded to said semiconductor substrate through said main dielectric layer; a second semiconductor layer of a first conductive type of a high impurity concentration having a front surface and being selectively formed on the front surface of said first semiconductor layer; a third semiconductor layer of a second conduction type of a high impurity concentration formed on said first semiconductor layer at a location apart from said second semiconductor layer so as to surround said second semiconductor layer; a ring-shaped insulating layer formed on said first semiconductor layer in a manner to surround an outer peripheral edge of said third semiconductor layer and to extend from the front surface of said first semiconductor layer up to said main dielectric layer; a first main electrode disposed on and joined to the front surface of said second semiconductor layer; a second main electrode disposed on and joined to the front surface of said third semiconductor layer; a rear surface electrode formed on the rear surface of said semiconductor substrate; and a first supplementary dielectric layer formed in said semiconductor substrate in a state contacting with said principal plane side of said main dielectric layer; wherein said first supplementary dielectric layer is formed in an area including a location right under said first main electrode and extending from said first main electrode side up to a range of more than 40% of a distance between said first and second main electrodes, and said first supplementary dielectric layer is formed of a porous oxide film.