A method of etching a metal includes performing at least two cycles of an etch process. A cycle of the etch process includes: performing a surface modification on an exposed surface of a metal layer over a substrate, performing a hydrogen treatment on the metal layer, and performing a cleaning treatment on the metal layer. The hydrogen treatment forms a layer of reaction products on the metal layer. The cleaning treatment removes the layer of reaction products.

A method of etching a metal includes performing at least two cycles of an etch process. A cycle of the etch process includes: performing a surface modification on an exposed surface of a metal layer over a substrate, performing a hydrogen treatment on the metal layer, and performing a cleaning treatment on the metal layer. The hydrogen treatment forms a layer of reaction products on the metal layer. The cleaning treatment removes the layer of reaction products.