SEMICONDUCTOR DEVICES AND DATA STORAGE SYSTEMS INCLUDING THE SAME

A semiconductor device includes a substrate, gate electrodes stacked in a first direction, channel structures penetrating through the gate electrodes, a horizontal conductive layer below the gate electrodes on the substrate, separation regions penetrating through the gate electrodes and the horizontal conductive layer, and extending in the first and second directions, a cell region insulating layer covering the gate electrodes, and an upper support layer on the separation regions and the cell region insulating layer and having openings to overlap the separation regions. Each of the separation regions includes a contact conductive layer and a first separation insulating layer in a trench, and has first regions below the openings and second regions alternating with the first regions. The contact conductive layer is in contact with the substrate in the first regions, and is spaced apart from the substrate by the first separation insulating layer in the second regions.