Semiconductor memory device.

摘要

First polycrystalline silicon layers (15) are insulatively disposed over a p-type semiconductor substrate. Second polycrystalline silicon layers (16) are formed on the substrate (11) adjacent to the first polycrystalline silicon layers (15). Third polycrystalline silicon layers (20) are insulatively disposed over the substrate (11) between the first polycrystalline silicon layers (15) and the second polycrystalline silicon layers (16). The third polycrystalline silicon layers (20) function as gates of MOS transistors, and the first polycrystalline silicon layers (15) function as digit lines in cooperation with the substrate (11). The second polycrystalline silicon layers (16) function as the digit lines, and are so formed as to extend on the substrate (11) and on the first polycrystalline silicon layers (15) through thick insulative layers (18).