Self-forming barrier for use in air gap formation

An etch back air gap (EBAG) process, comprising:

• forming an initial structure comprising a dielectric layer disposed on a substrate and a liner disposed to line a trench defined in the dielectric layer;
• impregnating a metallic interconnect material with dopant materials;
• filling a remainder of the trench with the impregnated metallic interconnect materials to form an intermediate structure;
• drive-out annealing of the intermediate structure to drive the dopant materials out of the impregnated metallic interconnect materials and thereby form a chemical- and plasma-attack immune material;
• applying a litho-stack for air gap processing to the intermediate structure;
• pattern transferring to expose a portion of the intermediate structure;
• removing the dielectric layer in the portion of the intermediate structure;
• and
• applying a dielectric capping stack for air gap processing to the intermediate structure.

An etch back air gap (EBAG) process, comprising:

• forming an initial structure comprising a dielectric layer disposed on a substrate and formed to define a trench;
• lining the trench with a liner;
• lining the liner with dopant materials;
• filling a remainder of the trench with metallic interconnect materials to form an intermediate structure;
• and
• drive-out annealing of the intermediate structure to drive the dopant materials through the liner,
• wherein:
• the lining of the trench comprises chemical vapor deposition (CVD) processing of tantalum (Ta), tantalum nitride (TaN), cobalt (Co) or ruthenium (Ru), and
• the lining of the liner comprises atomic layer deposition (ALD) or CVD processing of manganese nitride (MnN).

An etch back air gap (EBAG) process, comprising:

• forming an initial structure comprising a dielectric layer disposed on a substrate and formed to define a trench;
• lining the trench with a liner;
• lining the liner with dopant materials;
• filling a remainder of the trench with metallic interconnect materials to form an intermediate structure;
• drive-out annealing of the intermediate structure to drive the dopant materials through the liner;
• planarizing an upper surface of the intermediate structure;
• applying a litho-stack for air gap processing to the intermediate structure;
• pattern transferring to expose a portion of the intermediate structure;
• removing the dielectric layer in the portion of the intermediate structure;
• and
• applying a dielectric capping stack for air gap processing to the intermediate structure.