Patent ID: 6674124
Filing Date: 2004-01-06
Classification: H01L

Abstract:
A trench MOSFET device comprising:a silicon substrate of a first conductivity type; a silicon epitaxial layer of said first conductivity type over said substrate, said epitaxial layer having a lower majority carrier concentration than said substrate; a body region of a second conductivity type within an upper portion of said epitaxial layer; a trench extending into said epitaxial layer from an upper surface of said epitaxial layer, said trench extending through said body region, and said trench having trench sidewalls and a trench bottom; an oxide region lining said trench, said oxide region comprising a lower segment covering at least the trench bottom and upper segments covering at least upper regions of said trench sidewalls; a conductive region within said trench adjacent said oxide region; and a source region of said first conductivity type within an upper portion of said body region and adjacent said trench, wherein said lower segment of said oxide region is thicker than said upper segments of said oxide region such that shoulders are established in said oxide region adjacent said conductive region along said trench sidewalls, and wherein said lower segment of said oxide region consists of two structurally distinct portions, a thermally grown portion adjacent said trench and a deposited oxide portion adjacent said conductive region and in contact with said thermally grown portion having different operational characteristics than said deposited oxide portion, and wherein said upper segments of said oxide region consists of thermally grown oxide.