Semiconductor memory device and manufacturing method of the semiconductor memory device

A semiconductor memory device, comprising:

• a cell pillar structure including an external surface crossing a plurality of first axes and a plurality of second axes, the plurality of first axes and the plurality of second axes radially extending from a center point in a first plane, the plurality of first axes alternately arranged in a clockwise direction with the plurality of second axes, the external surface of the cell pillar structure spaced apart from the center point, the cell pillar structure extending in a stacking direction crossing the first plane;
• and
• a plurality of conductive layers spaced apart from each other in the stacking direction and surrounding the external surface of the cell pillar structure,
• wherein the cell pillar structure includes:
• a plurality of channel portions crossing the plurality of first axes, respectively, each of the plurality of channel portions including a radius of curvature defined between the center point and a vertex crossing a corresponding first axis among the plurality of first axes;
• a plurality of memory portions disposed between each of the plurality of conductive layers and the plurality of channel portions;
• and
• an isolation structure disposed between the plurality of channel portions and extending toward the center point,
• wherein each of the plurality of channel portions includes an end disposed at a first distance of 30% to 80% with respect to the radius of curvature from the vertex in an extending direction of the corresponding first axis.