SEMICONDUCTOR DEVICES AND DATA STORAGE SYSTEMS INCLUDING THE SAME

A semiconductor device includes a first semiconductor structure including circuit devices on a first substrate, a lower interconnection structure connected to the circuit devices, and a lower bonding structure connected to the lower interconnection structure; and a second semiconductor structure including a second substrate on the first semiconductor structure, a stopper layer in contact with a lower surface of the second substrate, gate electrodes stacked and spaced apart from each other in a vertical direction, channel structures penetrating through the gate electrodes, and each including a channel layer, an upper interconnection structure below the gate electrodes, a peripheral contact plug spaced apart from the second substrate, and an upper bonding structure bonded to the lower bonding structure, wherein the channel structures penetrate at least a portion of the stopper layer, and wherein the peripheral contact plug penetrates at least a portion of the stopper layer.