Patent ID: 7250653

Claim:
A silicon-oxide-nitride-oxide-silicon (SONOS) memory device including a memory type transistor in which a gate is formed with a SONOS structure on a semiconductor substrate, wherein the gate comprises: a tunneling oxide layer; a memory node structure formed on the tunneling oxide layer and having a trap site in which charges passing through the tunneling oxide layer are trapped, the memory node structure including crystal layers having nanocrystals that are separated from one another to trap the charges; and a gate electrode formed on the memory node structure, wherein the memory node structure comprises: a first memory node layer, including a first crystal layer and a first insulating layer, the first crystal layer being isolated from the second memory node layer; a second memory node layer, including a dielectric layer having a trap site with a predetermined density; and a third memory node layer, including a second crystal layer and a second insulating layer, the second crystal layer being isolated from the second memory node layer and the gate electrode.