In one embodiment, a method for etching a metal layer on a substrate may include providing a hydrogen-containing gas and an impurity gas to a plasma chamber; generating a plasma from the hydrogen-containing gas and the impurity gas in the plasma chamber, the plasma comprising hydrogen-containing ions; providing gaseous species from the plasma chamber to the substrate, wherein the providing the gaseous species comprises directing an ion beam comprising the hydrogen-containing ions formed from the plasma through an extraction aperture of an extraction plate disposed between the substrate and the plasma.