Trench MOSFET with sidewall spacer gates

A power semiconductor device, comprising:

• a semiconductor body of a first conductivity type;
• a plurality of trenches along a surface of said semiconductor body, each trench having sidewalls and a bottom surface;
• a gate insulation layer lining at least portions of the sidewalls and the bottom surface of each of said trenches;
• and
• spacer gates disposed along at least a portion of the sidewalls of each of said trenches, said spacer gates within each trench forming a void therein that extends from an upper end of said trench to the bottom surface of said trench.

A method for fabricating a power semiconductor device, comprising the steps of:

• etching a plurality of trenches in a semiconductor body comprising an epitaxial layer of a first conductivity type and a channel region of a second conductivity type formed atop said epitaxial layer, each trench having sidewalls and a bottom surface;
• forming a gate insulation layer along at least portions of the sidewalls and the bottom surface of each of said trenches;
• forming a layer of doped polysilicon within each of said trenches;
• etching said doped polysilicon within each trench to expose at least a portion of the bottom surface of each trench and thereby forming a gate electrode within each trench, said gate electrode within each trench extending along at least a portion of the sidewalls of said trench.