Semiconductor device and manufacturing method of semiconductor device

A semiconductor device comprising:

• conductive layers and interlayer insulating layers, which are alternately stacked;
• a select conductor spaced apart from the conductive layers in a direction in which the conductive layers and the interlayer insulating layers are stacked;
• a source layer spaced apart from the select conductor in the direction in which the conductive layers and the interlayer insulating layers are stacked;
• and
• cell plugs penetrating the conductive layers, the interlayer insulating layers, and the select conductor,
• wherein each of the cell plugs includes a channel layer and a memory layer surrounding the channel layer,
• wherein the conductive layers are spaced apart from the channel layer by the memory layer,
• wherein the channel layer extends into the source layer and is in contact with the source layer,
• wherein the select conductor includes a select base part surrounding the cell plugs, select protrusion parts protruding in a length direction of the cell plugs from the select base part, and a groove defined between the select protrusion parts,
• wherein the memory layer extends to surround a sidewall of the channel layer at a level between the source layer and each of the select protrusion parts of the select conductor, and
• wherein a bottom surface of the groove is defined by a surface of the select base part of the select conductor.