Patent ID: 7602015
Filing Date: 2009-10-13
Classification: H01L

Abstract:
1. A wafer that includes a plurality of trench type semiconductor devices formed therein; said wafer comprising a body of monocrystalline semiconductor material; a grown layer of epitaxially grown semiconductor material formed on the top surface of said body; said grown layer of epitaxial silicon having a generally central area surrounded by and continuous with an outer peripheral ring; said generally central area and outer peripheral ring having an impurity concentration of a given species; the impurity concentration of said outer peripheral ring being less than that of said generally central area, whereby the breakdown voltage of a trench type device singulated from said outer peripheral ring is substantially the same as that of a trench type device singulated from said generally central area, and wherein said trench type device singulated from said outer peripheral ring includes trenches that extend deeper into said body of monocrystalline semiconductor material than trenches of said trench type device from said generally central area.