Method to fabricate copper wiring structures and structures formed thereby

摘要

Techniques formation of high purity copper (Cu)-filled lines and vias are provided. In one aspect, a method of fabricating lines and vias filled with high purity copper with is provided. The method includes the following steps. A via is etched in a dielectric. The via is lined with a diffusion barrier. A thin ruthenium (Ru) layer is conformally deposited onto the diffusion barrier. A Cu layer is deposited on the Ru layer by a sputtering process. A reflow anneal is performed to eliminate voids in the lines and vias.

主权项

1. A method of fabricating a wiring structure comprising
etching an opening into a dielectric layer; lining said opening with a diffusion barrier; depositing a conformal ruthenium layer onto said diffusion barrier; depositing a copper layer onto said ruthenium layer by sputter deposition, wherein said copper layer comprises a first portion completely filling a bottom portion of said opening and a second portion completely filling an upper portion of said opening, wherein said portion is in direct contact with inner sidewalls of said conformal ruthenium layer, and wherein said first portion and said second portion of said copper layer are completely separated by a void; and performing a reflow anneal on said wiring structure, wherein said reflow anneal produces a void-free copper-filled structure.