Method for forming copper damascene structures by using a dual CMP barrier layer

摘要

An improved and new method for forming dual damascene CMP of copper lines and interconnects(studs) using a dual CMP barrier layer. The two layer polishing barrier produces planar copper structures and solves dishing problems caused when the soft exhibits to a high polishing rate relative to the surround material. The polishing barrier layers consist of bottom layer of TiN with a layer of Ta or TaN on top of TiN layer. The top layer has a low polishing and the bottom layer has high polishing similar to the polishing of copper. Dishing of the copper lines and interconnects is avoided by the method. The result is better uniformity across the substrate and better electrical performance due to the increased copper line cross-sectional.