SEMICONDUCTOR DEVICES AND DATA STORAGE SYSTEMS INCLUDING THE SAME

A semiconductor device includes a source structure, first and second stack structures, including first gate electrodes stacked on the source structure to be spaced apart from each other; a dummy structure on the source structure between the first and the second stack structures, and including second gate electrodes stacked to be spaced apart from each other; first separation regions passing through the first and second stack structures, and spaced apart from each other; second separation regions extending between each of the first and second stack structures and the dummy structure; channel structures passing through the first and second stack structures, and respectively including a channel layer, connected to the source structure through the channel layer; and first source contact structures passing through the dummy structure, and respectively including a first contact layer connected to the source structure through a lower surface of the first contact layer.