Method for depositing a diffusion barrier for copper interconnect applications

A method for depositing a diffusion barrier and a metal conductive layer on a wafer substrate, the method comprising:

• (a) depositing a first portion of the diffusion barrier over the surface of the wafer substrate;
• (b) etching through at least part of the first portion of the diffusion barrier at bottom portions of a plurality of vias to expose at least part of an underlying metal layer, while simultaneously depositing a second portion of the diffusion barrier on at least field regions of the wafer substrate, wherein the etching comprises removing the diffusion barrier material by impinging on the substrate with energetic inert gas ions;
• (c) depositing a third portion of the diffusion barrier, which covers at least the bottoms of the vias;
• and
• (d) depositing the metal conductive layer over the surface of the wafer substrate, such that the metal conductive layer is deposited on the third portion of the diffusion barrier at least at the bottom portions of the plurality of vias.