Barrier film integrity on porous low k dielectrics by application of a hydrocarbon plasma treatment

A method of fabricating an interconnect structure in an integrated circuit comprising:

• forming an etch stop/diffusion barrier over an underlying layer;
• depositing an interlayer dielectric on the etch stop/diffusion barrier;
• etching vias and trenches in the interlayer dielectric;
• treating the surface of the interlayer dielectric with plasma, so as to deposit a coating of carbon-rich polymeric material;
• depositing a barrier layer over the surface of the treated interlayer dielectric, so as to line the vias and the trenches;
• forming a copper alloy over the barrier layer, so as to fill the vias and the trenches;
• and
• planarizing the copper alloy.