Semiconductor device and electronic system including the same

A semiconductor device, comprising:

• a gate stack including insulating and conductive patterns, which are alternately stacked on top of each other;
• a memory channel structure penetrating the gate stack;
• a selection line structure on the gate stack;
• and
• a selection channel structure penetrating the selection line structure, wherein
• the memory channel structure comprises an insulating capping layer, a memory channel layer enclosing the insulating capping layer, and a memory layer enclosing the memory channel layer,
• the selection channel structure comprises a selection channel layer electrically connected to the memory channel layer, and a selection insulating structure enclosing the selection channel layer,
• the selection channel layer comprises a connecting portion on the memory channel structure and a pillar portion on the connecting portion, and
• the pillar portion overlaps with a center of the selection channel structure.

An electronic system, comprising:

• a main substrate;
• a semiconductor device on the main substrate;
• and
• a controller on the main substrate and electrically connected to the semiconductor device,
• wherein the semiconductor device comprises,
• a gate stack including insulating and conductive patterns, which are alternately stacked on top of each other,
• a memory channel structure penetrating the gate stack,
• a selection line structure on the gate stack, and
• a selection channel structure penetrating the selection line structure, wherein
• the memory channel structure comprises an insulating capping layer, a memory channel layer enclosing the insulating capping layer, and a memory layer enclosing the memory channel layer,
• the selection channel structure comprises a selection channel layer, which is electrically connected to the memory channel layer, and a selection insulating structure enclosing the selection channel layer,
• the selection channel layer comprises a connecting portion on the memory channel structure and a pillar portion on the connecting portion,
• the pillar portion overlaps with a center of the selection channel structure, when viewed in a plan view,
• a width of the connecting portion is larger than a width of the pillar portion,
• the selection channel layer comprises polysilicon, and
• an average size of grains in the connecting portion is less than an average size of grains in the pillar portion.