Provided herein are approaches for patterning a semiconductor device. Exemplary approaches include providing a set of photoresist patterning features atop a substrate, the set of patterning features having a surface roughness characterized by a set of protrusions and a set of indentations. The approaches further include implanting first ions into a sidewall surface of the set of photoresist patterning features to form a film layer having a non-uniform thickness along the sidewall surface, wherein a thickness of the film layer formed over the indentations is greater than a thickness of the film layer formed over the protrusions. The approaches further include sputtering the sidewall surface of the photoresist patterning features following the formation of the film layer to modify a portion of the film layer and/or the set of protrusions, wherein the sputtering includes directing second ions to photoresist patterning features at an angle with the sidewall surface.