Patent ID: 6693006
Filing Date: 2004-02-17
Classification: H01L

Abstract:
A method for increasing area of a trench capacitor, comprising:providing a substrate; forming a first oxide layer on the substrate; forming a first nitride layer on the first oxide layer; forming an opening through the first oxide layer and the first nitride layer into the substrate to expose the first oxide layer and the substrate, wherein the opening has a lower portion and an upper portion; removing a part of the first oxide layer exposed in the opening to form a first recess between the first nitride layer and the substrate; forming a second nitride layer in the first recess between the first nitride layer and the substrate; forming a second oxide layer on the first nitride layer and the opening; removing the second oxide layer from the upper portion of the opening; forming a third nitride layer on the upper portion of the opening; removing the second oxide layer from the lower portion of the opening; etching the substrate in the opening using the first nitride layer, the second nitride layer and the third nitride layer as a mask to form a second recess in the substrate in the lower portion of the opening; and removing the second nitride layer and the third nitride layer.