Method of reducing electromigration by ordering zinc-doping in an electroplated copper-zinc interconnect and a semiconductor device thereby formed

Abstract

A method of reducing electromigration in a graded reduced-oxygen dual-inlaid copper interconnect line by filling a via with a graded Cu-rich Cu—Zn alloy fill electroplated on a Cu surface using a stable chemical solution, and by controlling and ordering the Zn-doping thereof, which also improves interconnect reliability and corrosion resistance, and a semiconductor device thereby formed. The method involves using a graded reduced-oxygen Cu—Zn alloy as fill for the via in forming the dual-inlaid interconnect structure. The graded alloy fill is formed by electroplating, while varying electroplating parameters, the Cu surface in a unique chemical solution containing salts of Zn and Cu, their complexing agents, a pH adjuster, and surfactants, thereby electroplating the graded fill on the Cu surface; and annealing the electroplated graded Cu—Zn alloy fill; and planarizing the Cu—Zn alloy fill, thereby forming the graded reduced-oxygen dual-inlaid copper interconnect line.