Liner-free conductive structures

A structure, comprising:

• an epitaxial source/drain region on a substrate and comprising silicon;
• a contact structure, on the epitaxial source/drain region, comprising a silicide in contact with a top surface of the epitaxial source/drain region;
• a liner-free conductive structure on the contact structure, wherein the liner-free conductive structure comprises:
• an etch stop layer on the contact structure;
• a dielectric layer on the etch stop layer;
• and
• a ruthenium via extending into the contact structure, the etch stop layer, and the dielectric layer;
• and
• a metallization layer on a top surface of the liner-free conductive structure and comprising a metal oxide etch stop layer in contact with the ruthenium via.

A structure, comprising:

• a conductive structure on a substrate;
• a liner-free conductive structure on the conductive structure, wherein the liner-free conductive structure comprises:
• an etch stop layer on the conductive structure;
• an inter-layer dielectric (ILD) on the etch stop layer;
• and
• a liner-free ruthenium via extending into the conductive structure, the etch stop layer, and the ILD;
• and
• a metallization layer on a top surface of the liner-free conductive structure and comprising a metal oxide etch stop layer in contact with the liner-free ruthenium via.