METHOD OF FORMING A COPPER INTERCONNECT WITH CONCENTRATED ALLOY ATOMS AT COPPER-PASSIVATION INTERFACE

摘要

A method of forming a copper interconnect (62) provides a copper seed layer (54) in a recess (52) of a dielectric layer (50), this copper seed layer (54) having alloy atoms (56) that tend to improve electromigration performance of copper. After formation of the copper seed layer (54), copper (58) is formed on the copper seed layer (54), followed by chemical mechanical polishing of the copper (58). The polished copper (58) is then annealed, which drives the alloy atoms (56) to the top surface (60) of the copper (58) to improve the electromigration performance at the copper-passivation interface, while keeping low the concentration of the alloy atoms (56) within the interior of the copper line (62) to prevent increasing the resistance in the copper line (62).