The present disclosure describes a method for the planarization of ruthenium metal layers in conductive structures. The method includes forming a first conductive structure on a second conductive structure, where forming the first conductive structure includes forming openings in a dielectric layer disposed on the second conductive structure and depositing a ruthenium metal in the openings to overfill the openings. The formation of the first conductive structure includes doping the ruthenium metal and polishing the doped ruthenium metal to form the first conductive structure.