A 3D non-
volatile memory device may include a dummy string selection line, string selection lines, wordlines, bitlines, a ground selection line, and memory
layers. Each of the memory
layers comprising channel lines respectively coupled to the bitlines via first ends and coupled to a
common source line of the memory layer via second ends. The dummy string selection line, the string selection lines, the wordlines, and the ground selection line intersect with the channel lines, and each of the channel lines defines a memory string. Initializing the 3D non-
volatile memory device may include
programming string selection transistors coupled with the string selection lines to have one or more threshold values, and
programming a dummy string selection
transistor coupled with the dummy string selection line to have a predetermined threshold value, such that the dummy string selection
transistor together with the string selection transistors function as string selection transistors.