A semiconductor structure with improved capacitance of bit lines includes a substrate, a stacked memory structure, a plurality of bit lines, a first stair contact structure, a first group of transistor structures and a first conductive line. The first stair contact structure is formed on the substrate and includes conductive planes and insulating planes stacked alternately. The conductive planes are separated from each other by the insulating planes for connecting the bit lines to the stacked memory structure by stairs. The first group of transistor structures is formed in a first bulk area where the bit lines pass through and then connect to the conductive planes. The first group of transistor structures has a first gate around the first bulk area. The first conductive line is connected to the first gate to control the voltage applied to the first gate.