Patent ID: 8222136

Claim:
A method, comprising: providing a substrate having a source/drain region, the substrate having a metal gate formed thereon; forming a dielectric layer over the substrate, the dielectric layer covering the source/drain region and the metal gate; forming a first opening in the dielectric layer, the first opening extending through the dielectric layer and exposing a first surface; performing a first oxidation removal process to remove a first oxidation material formed on the first surface; filling the first opening with a metal material; forming a second opening in the dielectric layer, the second opening extending through the dielectric layer and exposing a second surface; and performing a second oxidation removal process to remove a second oxidation material formed on the second surface; wherein: the first surface is a surface of one of: the metal gate and the source/drain region; the second surface is a surface of the other one of: the metal gate and the source/drain region; and the first and second oxidation removal processes have different intensities measured in terms of at least direct-current (DC) voltage bias.