Patent ID: 7879736

Claim:
A method of forming a contact hole comprising: preparing a substrate having a silicon oxide layer that covers conductive structures including a metal silicide pattern; performing a first etching process on the silicon oxide layer to form a preliminary contact hole that exposes the substrate between the conductive structures with a first width; and performing a second etching process on the silicon oxide layer using a composition to form a silicon oxide layer pattern having a contact hole that exposes the substrate between the conductive structures with a second width substantially greater than the first width, the composition including from about 0.01 to about 2 percent by weight of ammonium bifluoride (NH 4 HF 2 ), from about 2 to about 35 percent by weight of an organic acid, from about 0.05 to about 1 percent by weight of an inorganic acid, and a remainder of a polar organic solvent.