A semiconductor memory device includes a semiconductor substrate in which a cell region and a core and peripheral region are defined. The device further comprises isolation layers formed in the semiconductor substrate to define active regions, a first gate electrode structure formed in the cell region and a second gate electrode structure formed in the core and peripheral region. Source and drain regions formed in the active regions on respective sides of each of the gate electrode structures and self-aligned contact pads are formed in the cell region in contact with the source and drain regions. An insulating interlayer is formed on the semiconductor substrate between the self-aligned contact pads, and etch stoppers are formed on the insulating interlayer between the self-aligned contact pads in the cell region.