Semiconductor memory device having wafer-to-wafer bonding structure

A semiconductor memory device includes first column line pads, having a longer width and a shorter width, defined on one surface of a cell wafer, and coupled to a memory cell array of the cell wafer; second column line pads, having a longer width and a shorter width, defined on one surface of a peripheral wafer that is bonded to the one surface of the cell wafer, coupled to a page buffer circuit of the peripheral wafer, and bonded respectively to the first column line pads; first row line pads defined on the one surface of the cell wafer, and coupled to the memory cell array; and second row line pads defined on the one surface of the peripheral wafer, coupled to a row decoder of the peripheral wafer, and bonded respectively to the first row line pads. The longer widths of the first and second column line pads and the longer widths of the first and second row line pads extend in the same direction.