Integrated circuit device

An integrated circuit device includes a substrate, a peripheral circuit structure disposed on the substrate, the peripheral circuit structure including a peripheral circuit and a lower wiring connected to the peripheral circuit, a conductive plate covering a portion of the peripheral circuit structure, a cell array structure disposed on the peripheral circuit structure with the conductive plate therebetween, the cell array structure including a memory cell array and an insulation layer surrounding the memory cell array, a through hole via passing through the insulation layer in a direction vertical to a top surface of the substrate to be connected to the lower wiring, and an etch guide member disposed in the insulation layer at the same level as the conductive plate to contact a portion of the through hole via.