US Patent 7629646 Trench MOSFET with terraced gate and manufacturing method thereof

A trench metal oxide semiconductor field effect transistor (MOSFET) with a terraced trench gate. An epitaxial layer with a plurality of trenches is provided and a gate oxide layer is covered the sidewalls and bottoms of the trenches. A polysilicon layer is filled in the trenches, wherein the polysilicon layer is higher than the sidewalls of the trenches to be used as a gate of the MOSFET. A plurality of sources and bodies are formed in the epitaxial layer, and the bodies at both sides of the trenches. An insulating layer is covered on the substrate, wherein a plurality of metal contact windows are provided. Metal plugs are filled in the metal contact windows to form metal connections for the MOSFET.