Stress management of barrier metal for resolving CU line corrosion

Abstract

In the presently disclosed invention, a method is provided to avoid damage to a copper interconnect while subjecting the interconnect to chemical-mechanical polishing (CMP). First, a copper barrier layer is formed in a damascene structure. Then, prior to the deposition of copper metal into the damascene openings, a barrier layer is formed on the inside walls of the damascene structure. In a first embodiment, the copper barrier layer is deposited at high temperature. Then, it is cooled down in a prescribed manner. Subsequently, a copper seed layer is formed over the barrier, which is followed by the electro-chemical deposition (ECD) of copper, to form the copper damascene interconnect. Alternatively, in a second embodiment, the copper layer is formed at low temperature. Then it is annealed at a high temperature, followed by wafer cooling. Subsequently, copper seed layer is formed over the barrier layer. Next, ECD copper is formed in the damascene structure. Finally, the interconnect so formed by either of the embodiments is subjected to CMP. It is found that, through the disclosed method of treatment of the barrier layer, process stresses that are normally formed within the barrier layer are relieved, and hence no damage is incurred during the final steps of chemical-mechanical polishing.

Dependencies are inferred from the claim text.