Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, comprising:

• alternately stacking first material layers and second material layers, wherein the second material layers are formed of a different material from the first material layers;
• forming a mask pattern including a first opening area on the stacked first and second material layers;
• forming a through-hole passing through the stacked first and second material layers by etching the stacked first and second material layers exposed by the first opening area;
• forming a channel pattern protruding from an inside of the through-hole over the through-hole;
• reducing a size of the mask pattern to define a second opening area, wherein the second opening area has a width greater than the first opening area and exposes a part of the uppermost surface of the stacked first and second material layers;
• forming a capping conductive pattern filling the second opening area;
• and
• removing the reduced mask pattern.