Self-forming, self-aligned barriers for back-end interconnects and methods of making same

An apparatus comprising:

• a semiconductor substrate;
• an interlayer dielectric (ILD) layer comprising silicon, carbon, and oxygen;
• a recess in the ILD layer having a bottom and sidewalls;
• a liner comprising a first metal along the bottom and sidewalls of the recess, wherein the first metal is selected from a group comprising tantalum, titanium, vanadium, ruthenium, osmium, cobalt, rhodium, and iridium;
• a metal conductor comprising copper in the recess, the metal conductor having a top surface opposite the bottom of the recess;
• and
• a cap disposed above the top surface of the metal conductor, the cap comprising a second metal, wherein the second metal is selected from a group comprising aluminum, manganese, titanium, and zirconium.

A method of manufacturing a semiconductor apparatus, comprising:

• forming an interlayer dielectric (ILD) layer on a semiconductor substrate, the ILD layer comprising silicon, carbon, and oxygen;
• forming a recess in the ILD layer, the recess having a bottom and sidewalls;
• forming a liner along the bottom and sidewalls of the recess, the liner comprising a first metal, wherein the first metal is selected from a group comprising tantalum, titanium, vanadium, ruthenium, osmium, cobalt, rhodium, and iridium;
• forming a metal conductor comprising copper in the recess, the metal conductor having a top surface opposite the bottom of the recess;
• and
• forming a cap above the top surface of the metal conductor, the cap comprising a second metal, wherein the second metal is selected from a group comprising aluminum, manganese, titanium, and zirconium.