Contact via structure including a barrier metal disc for low resistance contact and methods of making the same

A method of forming a structure, comprising:

• forming a first metal interconnect structure within a first dielectric material layer overlying a substrate, wherein the first metal interconnect structure comprises a first metallic nitride liner comprising a first conductive metal nitride and a first metallic fill material portion embedded within the first metallic nitride liner;
• forming a metal oxide plate by oxidizing a surface region of the first metallic fill material portion;
• forming a second dielectric material layer over the metal oxide plate and the first dielectric material layer;
• forming a second cavity including a pillar cavity through the second dielectric material layer, wherein a top surface of the metal oxide plate is physically exposed underneath the second cavity;
• expanding the second cavity by removing the metal oxide plate selective to the first metal interconnect structure to form an expanded second cavity including a recess cavity adjoined to the pillar cavity;
• depositing a second conductive metal nitride in the expanded second cavity;
• depositing a second metallic fill material in remaining volumes of the expanded second cavity;
• and
• removing portions of the second metallic fill material and the second conductive metal nitride from above a horizontal plane including a top surface of the second dielectric material layer.