| 摘要 |
PURPOSE: To provide a low voltage EEPROM cell having a long data storing time, by inserting a thin floating gate having a different energy and edge from that of a channel region into a gate stack of the N-channel EEPROM. CONSTITUTION: An N-channel EEPROM element is comprised of a material having a conductive band edge of a floating gate 10 with lower than 1 kT electron volt at least than a conductive band edge of a channel region 4 (or Fermi energy in case of metal or compound material including metal). Therefore, the flowing gate material has a larger electronic affinity than the material of the channel region. As a result, an insulating layer 112 which separates the floating gate from the channel can be formed thin (less than 100Å), a writing voltage is reduced and a writing cycle number which is performed without failure is increased. Also, during readout operation charges stored in the floating gate can not be returned to the channel region caused by the tunnel operation.
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