Example embodiments relate to a method of forming a photoresist pattern and a method of fabricating a semiconductor device using the same. The method of fabricating a semiconductor device comprises forming a mask layer on a substrate, forming a photoresist pattern on the mask layer, the photoresist pattern having pattern portions at a first height and recess portions, applying a first liquid onto the photoresist pattern, filling the recess portions with a pattern filler at a second height, the pattern filler having an higher etch rate than the etch rate of the pattern portions to the same etchant, removing the first liquid, etching the pattern filler after removing the first liquid, etching the mask layer via the photoresist pattern to form a mask pattern, and etching the substrate via the mask pattern to form a fine pattern.