Patent ID: 8652900

Claim:
A method for manufacturing a trench MOSFET comprising the steps of: growing an epitaxial layer with a first conductivity type upon a heavily doped substrate with a first conductivity type; applying a trench mask and forming a plurality of first gate trenches in the active area, and at least a second gate trench having wider trench width than said first gate trenches for gate connection, and multiple of third gate trenches in the termination area; growing a sacrificial oxide layer onto inner surface of all the gate trenches to remove the plasma damage; removing said sacrificial oxide and growing or depositing an oxide layer along said inner surface of all the gate trenches as gate oxide; depositing doped poly-silicon with said first conductivity type into all the gate trenches and etching back said doped poly-silicon; implanting said epitaxial layer with a second conductivity type dopant and diffusing it to form body regions without using body mask; etching back said doped poly-silicon within all said trenched gates to make its top surface below top surface of said body regions; depositing and planarizing another oxide layer functioning as contact interlayer to make it fill into the upper portion of all the gate trenches and on the top surface of mesa between every two adjacent of all the gate trenches; applying a contact 1 mask and dry oxide etching to remove part of said contact interlayer from upper portion of said first gate trenches and leaving only portion of said contact interlayer covering the top surface of doped poly-silicon; carrying out dopant Ion Implantation of said first conductivity and diffusing for source region formation; removing said contact 1 mask and applying a contact 2 mask; forming at least a body contact trench and at least a gate contact trench by successively dry oxide etching and dry silicon etching; and carrying out dopant Ion Implantation of said second conductivity with low energy to form a first body contact area wrapping at least the bottom of said body contact trench within said body region.