Process of forming a bottle-shaped trench

摘要

A process of forming a bottle-shaped trench. A semiconductor substrate with a trench is provided, on which a pad layer and hard mask layer are sequentially formed. A dielectric layer is formed on the hard mask layer to fill the trench. Part of the dielectric layer is etched to expose the sidewall of the upper portion of the trench. A spacer is formed on the sidewall. The residual dielectric layer in the trench is removed, and the partial trench not covered by the spacer is etched to a bottle shape.