Patent ID: 7230298
Filing Date: 2007-06-12
Classification: H01L

Abstract:
1. A transistor comprising: a single crystal substrate having a {100} plane surface, said surface being defined by an x-axis and an orthogonal y-axis, the x and y axes coinciding with crystallographic axes of said single crystal; a drain layer of a first conductivity type epitaxially grown on the surface of said single crystal substrate, so as to have a crystal structure oriented similar to said single crystal substrate; a body layer of a second conductivity type, said body layer disposed in contact with said drain layer; a narrow trench having a bottom parallel to the surface of the substrate and sidewalls perpendicular to the bottom and having a bottom with endwalls and sidewalls extending upward, formed across said body layer and said drain layer with the bottom and a portion of the sidewalls and the end walls disposed in said drain layer, the sidewalls of said narrow trench being aligned with one of the x-axis and y-axis so as to expose the bottom and the portion of the sidewalls to a {100} plane of said drain layer crystal structure, a source region disposed at an opening of said narrow trench in the body layer and spaced apart from said drain layer; a filling material, substantially free of voids, and doped with a dopant of the second conductivity type, formed of an epitaxially grown semiconductor in said narrow trench, said filling material having a bottom portion, side portions and end portions in contact with the bottom, sidewalls and endwalls of said narrow trench, and a top portion located below an interface between said body layer and said drain layer, the epitaxially grown semiconductor of said filling material being exposed to {100} planes of said drain layer crystal structure and thus having a crystal structure oriented similar to the drain layer's crystal structure; a gate film formed at least on a portion, at which the body layer is exposed, of sidewalls of said narrow trench; and a gate electrode plug, disposed in contact with said gate insulating film in said narrow trench, and electrically insulated from said filling material.