Present invention relates to a method of fabricating a semiconductor device that can facilitate the processes of etching a supporter and removing a mold layer. According to the present invention, a method of fabricating a semiconductor device semiconductor device comprises: sequentially forming a substructure over a substrate and a etch stop layer over the substructure; forming a stack structure of alternately stacked mold layers and supporter layers over the etch stop layer; forming a plurality of supporter holes in the stack structure exposing the etch stop layer; forming a sacrificial layer filling each of the plurality of the supporter holes; forming a plurality of lower electrode openings exposing the substructure by etching the sacrificial layer and the stack structure; and forming a lower electrode inside the plurality of lower electrode openings.