A method of planarizing a metal conductive layer on a substrate is provided. In one embodiment, a substrate having a metal conductive layer disposed on a top surface of the substrate is provided on a substrate support. The substrate support is rotated and the top surface of the substrate is contacted with a liquid etching composition. The metal conductive layer is then exposed to an etchant gas in order to planarize the top surface of the metal conductive layer. Also provided is an apparatus for etching a metal conductive layer on a substrate. The apparatus comprises a container, a substrate support disposed in the container, a rotation actuator attached to the substrate support, and a fluid delivery assembly disposed in the container.