Polylactic acid-backbone graft and bottlebrush copolymers are synthesized by polymerizing a lactide-functionalized macromonomer using ring opening polymerization. The method includes coating an ink containing metal particles on a surface of a substrate, drying the ink to attach the metal particles to the surface of the substrate, and differentially etching the surface of the substrate using the metal particles as a catalyst to form an uneven portion. In a portion of the device isolation film a first recess is formed, and in a portion of the fin active region a second recess having a depth shallower than the first recess is formed.