Semiconductor Devices Including Data Storage Patterns

A semiconductor device is provided including a base insulating layer on a substrate; a first conductive line that extends in a first direction on the base insulating layer; data storage structures on the first conductive line; selector structures on the data storage structures, each of the selector structures including a lower selector electrode, a selector, and an upper selector electrode; an insulating layer in a space between the selector structures; and a second conductive line disposed on the selector structures and the insulating layer and extended in a second direction intersecting the first direction. An upper surface of the insulating layer is higher than an upper surface of the upper selector electrode.