An integrated circuit device includes a channel layer in a channel hole penetrating a conductive line and an insulating layer, a charge trap pattern inside the channel hole between the conductive line and the channel layer, and a dummy charge trap pattern inside the channel hole between the insulating layer and the channel layer. In order to manufacture the integrated circuit device, a channel hole penetrating an insulating layer and a mold layer is formed. A mold indent connected to the channel hole is formed. A preliminary dielectric pattern is formed in the mold indent. The preliminary dielectric pattern is oxidized to form a first blocking dielectric pattern. A charge trap layer is formed in the channel hole. The mold layer is removed to form a conductive space. A portion of the charge trap layer is removed to form charge trap patterns and dummy charge trap patterns.