PRE-ETCH TREATMENT FOR METAL ETCH

A method of processing a substrate that includes: exposing a substrate to a first plasma including carbon, the substrate including a first layer including a dielectric material and a second layer including a metal, the first plasma forming a first carbonaceous deposit over the first layer and a second carbonaceous deposit over the second layer; exposing the first carbonaceous deposit and the second carbonaceous deposit to a second plasma including halogen, the second plasma selectively etching the second carbonaceous deposit relative to the first carbonaceous deposit to expose a surface of the second layer; and exposing the first carbonaceous deposit and the exposed surface of the second layer to the second plasma to selectively etch the second layer relative to the first carbonaceous deposit, the first carbonaceous deposit protecting the first layer from being etched by the second plasma.