Patent ID: 7354856

Claim:
A method of forming a damascene structure, comprising: providing a substrate having a conductive layer formed in a first insulating layer; forming a protective layer above the conductive layer; forming an etching stop layer above the protective layer and the first insulating layer; forming a second insulating layer above the etching stop layer; forming a first patterned photoresist layer above the second insulating layer, the first patterned photoresist layer having a first pattern; etching the first pattern into the second insulating layer and the etching stop layer to form a first opening; at least partially filling the first opening with a via plug; forming an anti-reflective coating (ARC) layer above the second insulating layer; forming a second patterned photoresist layer above the ARC layer, the second photoresist layer having a second pattern; and etching the second pattern into portions of the via plug, second insulation layer, and the ARC layer to form a second opening, wherein a tapered sidewall portion is formed at the interface of the first and second openings.