A semiconductor device includes a circuit board, a bottom plate, landing pads, a stack, support pillars, and memory pillars. The circuit board includes circuit structures and wires and has a peripheral area, an array area and a staircase area disposed between the peripheral area and the array area. The bottom plate is disposed on the circuit board, and the bottom plate includes a bottom conductive layer. The landing pads are embedded in at least a top portion of the bottom conductive layer and contact the bottom conductive layer in the staircase area. The stack is disposed on the bottom plate, and includes conductive layers and insulating layers alternately stacked along a first direction. The support pillars pass through the stack along the first direction and extend to the landing pads in the staircase area. The memory pillars pass through the stack along the first direction in the array area.