In certain embodiments, a method of forming a semiconductor device includes forming a patterned resist layer over a hard mask layer using an extreme ultraviolet (EUV) lithography process. The hard mask layer is disposed over a substrate. The method includes patterning the hard mask layer using the patterned resist layer as an etch mask. The method includes smoothing the hard mask layer by forming, using a first atomic layer etch step, a first layer by converting a first portion of the hard mask layer, and by removing, using a second atomic layer etch step, the first layer.