Patent ID: 8004893

Claim:
A three-dimensional nonvolatile memory device, comprising: a first NAND-type string of EEPROM cells having a first plurality of string selection transistors therein electrically connected in series, said first plurality of string selection transistors comprising a first plurality of depletion-mode transistors and a first enhancement-mode transistor; a second NAND-type string of EEPROM cells having a second plurality of string selection transistors therein electrically connected in series, said second plurality of string selection transistors comprising a second plurality of depletion-mode transistors and a second enhancement-mode transistor, said first enhancement-mode transistor stacked vertically relative to one of the second plurality of depletion-mode transistors and said second enhancement-mode transistor stacked vertically relative to one of the first plurality of depletion-mode transistors; a first string selection line electrically connected to a gate electrode of the first enhancement-mode transistor and a gate electrode of the one of the second plurality of depletion-mode transistors; and a second string selection line electrically connected to a gate electrode of the second enhancement-mode transistor and a gate electrode of the one of the first plurality of depletion-mode transistors; wherein each of the first plurality of string selection transistors in said first NAND-type string of EEPROM cells is electrically coupled to a corresponding one of a plurality of string selection lines; wherein each of the second plurality of string selection transistors in said second NAND-type string of EEPROM cells is electrically coupled to a corresponding one of the plurality of string selection lines; wherein each of the first plurality of string selection transistors in said first NAND-type string of EEPROM cells is electrically coupled to only one of the plurality of string selection lines; and wherein each of the second plurality of string selection transistors in said second NAND-type string of EEPROM cells is electrically coupled to only one of the plurality of string selection lines.