Semiconductor memory devices

A semiconductor memory device comprising:

• a stack structure including a plurality of word lines stacked on a substrate;
• a plurality of first vertical pillars and a plurality of second vertical pillars that extend through the stack structure;
• a first string select line overlapping the plurality of first vertical pillars in a plan view;
• and
• a second string select line overlapping the plurality of second vertical pillars in the plan view and being horizontally spaced apart from the first string select line,
• wherein, in the plan view, at least one of the plurality of first vertical pillars and the plurality of second vertical pillars is overlapped by an area between the first and second string select lines.

An integrated circuit device comprising:

• a stack structure including a plurality of word lines stacked on a substrate;
• a first vertical pillar extending through the stack structure;
• a first string select line overlapping the first vertical pillar in a plan view and extending longitudinally in a first direction, the first string select line comprising a first sidewall and a second sidewall opposite the first sidewall, and the first vertical pillar being closer to the first sidewall of the first string select line than the second sidewall of the first string select line;
• and
• a first string channel pillar extending through the first string select line and being electrically connected to the first vertical pillar,
• wherein a center of the first string channel pillar is offset from a center of the first vertical pillar in a second direction traversing the first direction away from the first sidewall of the first string select line in the plan view.