Semiconductor devices and electronic systems including the same

A semiconductor device comprising:

• a stack extending in a first direction and comprising electrodes vertically stacked on a substrate;
• first and second string selection lines on the stack and extending in the first direction;
• an upper separation pattern on the stack and between the first and second string selection lines;
• a lower vertical structure in the stack;
• an upper vertical structure that is in the first string selection line or the second string selection line and is electrically connected to the lower vertical structure;
• a landing conductive pattern on the upper vertical structure;
• a bit line crossing the stack and extending in a second direction;
• and
• a contact plug electrically connecting the landing conductive pattern to the bit line,
• wherein, in the first direction, a first length of the upper vertical structure is larger than a first width of the contact plug, and
• wherein, in the second direction, a second width of the upper vertical structure is smaller than a second length of the contact plug.

An electronic system comprising:

• a semiconductor device including a cell array and an input/output pad that is electrically connected to a peripheral circuit near the cell array;
• and
• a controller that is electrically connected to the semiconductor device through the input/output pad and is configured to control the semiconductor device,
• wherein the cell array comprises:
• a stack extending in a first direction and comprising electrodes vertically stacked on a substrate;
• first and second string selection lines on the stack and extending in the first direction;
• an upper separation pattern on the stack and between the first and second string selection lines;
• a lower vertical structure in the stack;
• an upper vertical structure that is in the first string selection line or the second string selection line and is electrically connected to the lower vertical structure;
• a landing conductive pattern on the upper vertical structure;
• a bit line crossing the stack and extending in a second direction;
• and
• a contact plug electrically connecting the landing conductive pattern to the bit line,
• wherein, in the first direction, a first length of the upper vertical structure is larger than a first width of the contact plug, and
• wherein, in the second direction, a second width of the upper vertical structure is smaller than a second length of the contact plug.