Patent ID: 7025661

Claim:
A chemical mechanical polishing (CMP) process comprising: providing a CMP tool having a first polishing platen and a second polishing platen; providing a substrate having thereon a top metal layer stacked directly on a lower barrier layer; placing said substrate on said first polishing platen with said top metal layer in contact with said first polishing platen; dispersing, onto said first polishing platen, a first slurry being selective to said barrier layer; polishing said top metal layer on said first polishing platen at a substantial constant removal rate, wherein an entire thickness of said top metal layer is polished at said constant removal rate and said substrate is not removed from said first polishing platen until said barrier layer is exposed; and after removing said top metal layer, placing said substrate on said second polishing platen and polishing said exposed barrier layer by using said second polishing platen and a second slurry.