Reduction of polysilicon residue in a trench for polysilicon trench filling processes

摘要

A method of fabricating a semiconductor device includes forming at least one trench from a top side of a semiconductor layer, wherein the trench is lined with a trench dielectric liner and filled by a first polysilicon layer. The surface of the trench dielectric liner is etched, wherein dips in the trench dielectric liner are formed relative to a top surface of the first polysilicon layer which results in forming a protrusion including the first polysilicon layer. The first polysilicon layer is etched to remove at least a portion of the protrusion. A second dielectric layer is formed over at least the trench after etching the first polysilicon layer. A second polysilicon layer is deposited. The second polysilicon layer is etched to remove it over the trench and provide a patterned second polysilicon layer on the top side of the semiconductor layer.