Patent ID: 7626228

Claim:
A NAND-type nonvolatile memory device, comprising: a semiconductor substrate; a first ground selection line and a first string selection line disposed on the substrate in parallel to each other; a plurality of parallel first word lines interposed on the substrate between the first ground selection line and the first string selection line; a first impurity-doped region formed in the semiconductor substrate adjacent to the first word lines, the first ground selection line, and the first string selection line; a first interlayer dielectric layer disposed on the first ground selection line, the first string selection line, the plurality of first word lines, and the semiconductor substrate; an epitaxial contact plug that contacts the semiconductor substrate through the first interlayer dielectric layer; a single crystalline semiconductor layer disposed on the first interlayer dielectric layer that contacts the epitaxial contact plug; a plurality of parallel second word lines disposed on the single crystalline semiconductor layer; a second impurity-doped region formed in the single crystalline semiconductor layer adjacent to the second word lines; and a second interlayer dielectric layer disposed on the plurality of second word lines and the single crystalline semiconductor layer; wherein the epitaxial contact plug comprises a first epitaxial contact plug that is located between the plurality of first word lines and the first ground selection line and a second epitaxial contact plug that is located between the plurality of first word lines and the first string selection line, the first epitaxial contact plug electrically connecting the first impurity-doped region between the plurality of first word lines and the first ground selection line to the second impurity-doped region on a first side of the second word lines and the second epitaxial contact plug electrically connecting the first impurity-doped region between the plurality of first word lines and the first string selection line to the second impurity-doped region on a second side of the second word lines.