Copper electromigration inhibition by copper alloy formation

摘要

A method of forming a copper structure, comprising the following steps. A substrate is provided. A patterned dielectric layer is formed over the substrate with the patterned dielectric layer having an opening exposing a portion of the substrate. The opening having exposed sidewalls. A Sn layer is formed directly upon the exposed sidewalls of the opening. A copper seed layer is formed upon the Sn layer within the opening. A bulk copper layer is formed over the copper seed layer, filling the opening. The structure is thermally annealed whereby Sn diffuses from the Sn layer into the copper seed layer and the bulk copper layer forming CuSn alloy within the copper seed layer and the bulk copper layer.