A method for processing a substrate may include providing a patterning feature on the substrate, the patterning feature having a sidewall. The method may further include implanting a first ion species into the patterning feature during a first exposure, the first ion species having a first implantation depth; and implanting a second ion species into the patterning feature during a second exposure, the second ion species having a second implantation depth less than the first implantation depth.