US Patent 11469139 Bottom-up formation of contact plugs

A method includes etching a dielectric layer to form a trench in the dielectric layer, depositing a metal layer extending into the trench, performing a nitridation process on the metal layer to convert a portion of the metal layer into a metal nitride layer, performing an oxidation process on the metal nitride layer to form a metal oxynitride layer, removing the metal oxynitride layer, and filling a metallic material into the trench using a bottom-up deposition process to form a contact plug.