Semiconductor device and manufacturing method of semiconductor device

A semiconductor device comprising:

• a first gate stack structure and a second gate stack structure, which face each other;
• channel patterns extending in a first direction to penetrate the first gate stack structure and the second gate stack structure;
• memory patterns extending along outer walls of the channel patterns;
• and
• a source contact structure disposed between the first gate stack structure and the second gate stack structure,
• wherein the source contact structure includes a vertical part extending in the first direction and horizontal protrusion parts protruding toward a sidewall of the first gate stack structure and a sidewall of the second gate stack structure from both sides of the vertical part, and
• wherein the source contact structure includes a first part, a second part, and a third part sequentially disposed along the first direction, a width of the second part being greater than each of a width of the first part and a width of the third part.