In a method, a stack structure including a plurality of first interlayer sacrificial layers and a plurality of second interlayer sacrificial layers that are alternately stacked is formed over a substrate. A trench penetrating the stack structure is formed. A channel layer covering a sidewall surface of the trench is formed. The plurality of first interlayer sacrificial layers are selectively removed to form a plurality of first recesses. The plurality of first recesses are filled with a conductive material to form a plurality of channel contact electrode layers. The plurality of second interlayer sacrificial layers are selectively removed to form a plurality of second recesses. A plurality of interfacial insulation layers, a plurality of ferroelectric layers and a plurality of gate electrode layers are formed in the plurality of second recesses.