A method of forming a semiconductor memory device, a semiconductor memory device, and a memory system, the method including forming a thin film structure on a semiconductor substrate such that the thin film structure includes a plurality of thin films; patterning the thin film structure to form a through region in the thin film structure; forming a first silicon film using a first precursor such that the first silicon film covers the through region; and forming a second silicon film on the first silicon film using a second precursor, wherein the first precursor is different from the second precursor.