SEMICONDUCTOR DEVICE AND DATA STORAGE SYSTEM INCLUDING THE SAME

A semiconductor device and a data storage system, the device including a lower structure; and an upper structure on the lower structure and including a memory cell array, wherein the lower structure includes a semiconductor substrate, first and second active regions spaced apart from each other in a first direction on the semiconductor substrate, the first and second active regions being defined by an isolation insulating layer on the semiconductor substrate, and first and second gate pattern structures extending in the first direction to cross the first and second active regions, respectively, on the semiconductor substrate, the first gate pattern structure and the second gate pattern structure have first and second end portions spaced apart from each other in a facing manner in the first direction, respectively, and the first and second end portions are concavely curved in opposite directions away from each other in a plan view.