A method of fabricating a semiconductor device is provided. The method includes forming at least one etch target film on a substrate, forming a first reflowable etch mask on the at least one etch target film, patterning the etch target film using the first reflowable etch mask. The method further includes reflowing the first reflowable etch mask to form a second etch mask and patterning the etch target film using the second etch mask.