Abstract: Method and apparatus for etching an optically transparent layer disposed on a substrate, such as a photolithographic reticle, are provided. In one aspect, a method is provided for etching a substrate comprising placing the reticle on a support member in a processing chamber, positioning the reticle on a support member in a processing chamber, wherein the reticle comprises a patterned metal photomask layer formed on an optically transparent material, and a patterned resist material deposited on the patterned metal photomask layer, introducing a processing gas comprising one or more fluorine containing hydrocarbons and one or more chlorine-containing gases into the processing chamber, delivering power to the processing chamber to generate a plasma by applying a source RF power to a coil and applying a bias power to the support member, and etching exposed portions of the optically transparent material.