Method for increasing area of a trench capacitor

摘要

A method for increasing area of a trench capacitor. First, a first oxide layer and a first nitride layer are sequentially formed on a substrate. An opening is formed through the first oxide layer and the first nitride layer into the substrate. A part of the first oxide layer exposed in the opening is removed to form a first recess, and then a second nitride layer is formed therein. A second oxide layer is formed in the lower portion of the opening. After a third nitride layer is formed in the upper portion of the opening, the second oxide layer is removed. The substrate in the opening is etched using the first nitride layer, the second nitride layer and the third nitride layer as a mask to form a second recess in the lower portion of the opening. The second nitride layer and the third nitride layer are then removed.