Patent ID: 7910486
Filing Date: 2011-03-22
Classification: B82Y,H01L

Abstract:
1. A method for forming a semiconductor device, the method comprising: forming a plurality of trenches in a top surface of a first semiconductor layer of a first conductivity type, the trenches forming mesas in the first semiconductor layer; forming by epitaxial growth a first epitaxial layer of a second conductivity type on the top surface of the first semiconductor layer covering at least sidewalls of the trenches; forming a first dielectric layer in the trenches, the first dielectric layer filling at least part of the trenches; forming a gate dielectric layer on the sidewalls of at least a first trench above the first dielectric layer and adjacent to the first epitaxial layer; forming a gate conductive layer in the first trench, the gate conductive layer being formed above the first dielectric layer and adjacent the gate dielectric layer; and providing a second semiconductor layer of the second conductivity type located at a bottom surface of the first semiconductor layer, the first epitaxial layer being electrically connected to the second semiconductor layer, wherein the first epitaxial layer is disposed along the sidewalls of the trenches and has uniform doping concentration, the first epitaxial layer having a first thickness and a first doping concentration and a mesa of the first semiconductor layer having a second thickness in a horizontal dimension and a second doping concentration, the first and second thicknesses and the first and second doping concentrations being selected to achieve charge balance in operation.