Semiconductor devices and data storage systems including the same

Abstract

A semiconductor device includes: a substrate that includes a first region and a second region; gate electrodes stacked on the first region in a first direction, extend by different lengths in a second direction on the second region, and respectively including a pad region having an upper surface that is upwardly exposed in the second region; interlayer insulating layers alternately stacked with the gate electrodes; channel structures that extend in the first direction and penetrate through the gate electrodes; plug insulating layers alternately disposed with the interlayer insulating layers and parallel to the gate electrodes below the pad region; and contact plugs that extend in the first direction and respectively penetrate through the pad region and the plug insulating layers below the pad region. In each of the gate electrodes, the pad region has physical properties that differ from physical properties of regions other than the pad region.