Patent ID: 6713341
Filing Date: 2004-03-30
Classification: H01L

Abstract:
A method of forming the bottle-shaped trench in a semiconductor substrate, suitable for formation of the capacitor of DRAM, comprising the steps of:(a) forming a hard mask having an opening on the semiconductor substrate; (b) etching the semiconductor substrate through the opening of the hard mask to create a trench, wherein the trench has a top portion and a bottom portion; (c) forming an oxide film on the surfaces of the trench and the hard mask; (d) filling a shield material in the bottom portion of the trench; (e) removing a part of the oxide film to leave the oxide film protected by the shield material and expose the surface of the semiconductor substrate at the top portion of the trench; (f) removing the shield material to expose the oxide film formed on the bottom portion of the trench; (g) forming a nitride film on the top portion of the trench; (h) removing the oxide film to expose the surface of the semiconductor substrate at the bottom portion of the trench; (i) etching the semiconductor substrate through the bottom portion of the trench by a solution of hydrogen peroxide and hydrofluoric acid as the etchant to form the bottle-shaped trench; and (j) removing the nitride film.