A hardmask structure including a plurality of hardmask layers is formed on a target layer in a first area and a second area, a first photoresist pattern in the first area and a second photoresist pattern in the second area are formed, a reversible hardmask pattern including a plurality of openings is formed by transferring shapes of the first and second photoresist patterns to a reversible hardmask layer that is one of the plurality of hardmask layers, a gap-fill hardmask pattern is formed by filling some of the plurality of openings formed in the first area with a gap-fill hardmask pattern material, and a feature pattern is formed in the target layer by transferring a shape of the gap-fill hardmask pattern to the target layer in the first area and a shape of the reversible hardmask pattern to the target layer in the second area.