Method for manufacturing semiconductor device having trench filled with polysilicon

摘要

First, a trench of a semiconductor substrate is filled with a polysilicon film deposited on the surface of the semiconductor substrate. A selective thin film having etching selectivity with respect to the polysilicon film is formed on the polysilicon film. Then, the selective thin film is etched (etched back) so that a part of the selective thin film remains in a depression of the polysilicon film, as a self-aligning mask. The polysilicon film is further etched with the self-aligning mask, thereby forming a polysilicon embedded layer in the trench with a flat surface.