Multi-bit non-volatile memory device, method of operating the same, and method of manufacturing the multi-bit non-volatile memory device

A unit cell of a multi-bit nonvolatile memory device, the unit cell comprising:

• a semiconductor substrate;
• first and second storage nodes disposed on the semiconductor substrate parallel to an upper surface of the semiconductor substrate;
• first and second channels disposed between the storage nodes parallel to the upper surface of the semiconductor substrate;
• third and fourth channels disposed between the first and second channels perpendicularly to the upper surface of the semiconductor substrate;
• third and fourth storage nodes disposed on opposite sides of the third and fourth channels perpendicularly to the upper surface of the semiconductor substrate;
• a control gate, having a box form and surrounding the storage nodes, formed on the semiconductor substrate;
• and
• an insulator formed between the channels and the storage nodes, between the channels and the control gate, and between the storage nodes and the control gate.