Patent ID: 7628866

Claim:
A method of cleaning a wafer after an etching process for forming an opening, comprising the steps of: providing a wafer, wherein the wafer has an etching stop layer, a dielectric layer and a patterned metal hard mask sequentially formed thereon, and the patterned metal hard mask is used to define the opening in the dielectric layer such that the opening exposes a portion of the etching stop layer; performing a dry etching process inside a reaction chamber with an environment of helium to remove the etching stop layer exposed by the opening, wherein a polymer and a metal fluoride formed from the patterned metal hard mask in the dry etching process are both deposited on the wafer; performing a dry cleaning process to soften the polymer and to remove a portion of the polymer deposited on the wafer using a gaseous mixture of hydrogen and nitrogen as a reactive gas, after the dry etching process; and performing a wet cleaning process to remove the polymer and the metal fluoride deposited on the wafer using hydrofluoric acid after the dry cleaning process, wherein the patterned metal hard mask remains on the wafer after the wet cleaning process.