Three-dimensional semiconductor memory devices with increased integration

A three-dimensional semiconductor memory device comprising:

• a stack structure that is on a substrate and includes a plurality of gate electrodes;
• a first vertical structure, a second vertical structure, a third vertical structure, and a fourth vertical structure that penetrate the stack structure and are arranged in a zigzag shape comprising a sequence of the first vertical structure, the second vertical structure, the third vertical structure, and then the fourth vertical structure at different respective positions along a first direction;
• and
• a first bit line that extends in the first direction,
• wherein the first bit line vertically overlaps the second vertical structure and the fourth vertical structure, centers of the second and fourth vertical structures being spaced apart at the same distance from the first bit line,
• wherein the first vertical structure is spaced apart at a first distance from the first bit line,
• wherein the third vertical structure is spaced apart at a second distance from the first bit line,
• wherein a portion of the first vertical structure overlaps a portion of the third vertical structure in the first direction,
• wherein the first distance is greater than the second distance and is less than a distance between the portion of the first vertical structure and the portion of the third vertical structure,
• wherein the gate electrodes include a first string select gate electrode and a second string select gate electrode that are spaced apart in the first direction,
• wherein the first vertical structure, the second vertical structure, the third vertical structure, and the fourth vertical structure penetrate the first string select gate electrode, and
• wherein the three-dimensional semiconductor memory device further comprises a fifth vertical structure, a sixth vertical structure, a seventh vertical structure, and an eighth vertical structure that penetrate the second string select gate electrode and correspond to the first vertical structure, the second vertical structure, the third vertical structure, and the fourth vertical structure, respectively.