Abstract: A method includes forming a plurality of first mandrels over a substrate, forming an overcoat layer over the plurality of first mandrels, and inducing a crosslinking reaction within the overcoat layer and form a crosslinked overcoat layer. The method further includes exposing the substrate to a radiation to generate a plurality of acid molecules within the plurality of first mandrels, diffusing a portion of the plurality of acid molecules from the plurality of first mandrels into portions of the crosslinked overcoat layer, and inducing a decrosslinking reaction within the portions of the crosslinked overcoat layer and form de-crosslinked regions. Unmodified regions of the crosslinked overcoat layer form a plurality of second mandrels. The method further includes selectively removing the de-crosslinked regions. The plurality of first mandrels and the plurality of second mandrels form a mandrel pattern over the substrate.