The present invention provides a double photolithography method in which, after a first photoresist pattern including a crosslinkable agent is formed on a semiconductor substrate, a crosslinkage is formed in a molecular structure of the first photoresist pattern. A second photoresist film may be formed on a surface of the semiconductor substrate on which the crosslinked first photoresist patterns are formed. Second photoresist patterns may be formed by exposing, post-exposure baking, and developing the second photoresist film.