Provided herein may be a semiconductor device and a method of manufacturing the same. The method of manufacturing the semiconductor device may include forming a tunnel insulating layer in a channel hole passing through a preliminary stack structure in which interlayer insulating layers and material layers are alternately stacked. The method may include forming recess areas by removing the material layers exposed through a slit passing through the preliminary stack structure. The method may include forming a data storage layer in the recess areas through the slit. The thickness of the data storage layer may be formed regardless of a size of the channel hole.