Method of forming a bottle-shaped trench in a semiconductor substrate

摘要

A method of forming a bottle-shaped trench in a semiconductor substrate. First, the semiconductor substrate is selectively etched to form a trench, wherein the trench has a top portion and a bottom portion. An oxide film is then formed on the top portion of the trench. Next, the semiconductor substrate is etched through the bottom portion of the trench with a diluted ammonia solution as the etchant to form a bottle-shaped trench followed by removal of the oxide film.