Semiconductor device and method of manufacturing a semiconductor device

A semiconductor device comprising:

• a first electrode layer;
• a second electrode layer positioned over the first electrode layer;
• a sub-electrode layer positioned between the first electrode layer and the second electrode layer;
• a first buffer layer positioned between the first electrode layer and the sub-electrode layer;
• a second buffer layer positioned between the sub-electrode layer and the second electrode layer;
• an insulating pattern extending through the second electrode layer, through the second buffer layer, and into the sub-electrode layer;
• a conductive pattern extending through the insulating pattern and electrically connected to the sub-electrode layer and the first electrode layer;
• a stack positioned on the second electrode layer;
• a first contact plug extending through the stack and electrically connected to the conductive pattern;
• and
• a second contact plug extending through the stack and electrically connected to the second electrode layer.