Semiconductor device and method of manufacturing the semiconductor device

A semiconductor device comprising:

• a substrate comprising a cell area and a read-only memory area;
• a stack located over the read-only memory area of the substrate;
• a gate structure located over the cell area of the substrate;
• a conductive source structure located between the gate structure and the substrate, and extending between the stack and the read-only memory area of the substrate to vertically overlap the stack;
• a channel structure connected to the conductive source structure by extending through the gate structure;
• a read-only memory comprising a first contact plug passing through the conductive source structure and a second contact plug connected to the first contact plug by extending through the stack;
• and
• an insulating spacer interposed between the first contact plug and the conductive source structure.