Oxygen-free etching of non-volatile metals

A method of processing a substrate, the method comprising;

• loading the substrate in a processing chamber, the substrate comprising a non-volatile metal layer, an oxide layer, and a dielectric layer, the oxide layer comprising an oxide of the non-volatile metal, a surface of the substrate comprising the oxide layer and the dielectric layer;
• performing a pretreatment by exposing the substrate to a treatment gas to remove the oxide layer and expose the non-volatile metal layer;
• performing a non-plasma oxygen-free etch process selective to the dielectric layer by:
• exposing the substrate to chlorine (Cl2) in the processing chamber, the Cl2 reacting with the non-volatile metal to form an intermediate;
• and
• exposing the substrate to a ligand-exchange agent in the processing chamber, the ligand-exchange agent reacting with the intermediate to form volatile products, removing the non-volatile metal from the surface of the substrate.