A novel 2-bit/cell nitride storage flash memory with greater than 1M P/E-cycle endurance

A novel 2-bit/cell nitride storage flash memory is proposed. It uses conventional CHE (channel hot electron) programming, BTBT HH (band-to-band tunneling hot hole) erase, and a unique negative FN (Fowler-Nordheim) reset, executed on p⁺-gate devices. Periodic -FN resets can restore V_t operation window by removing hard-to-erase electrons trapped in the channel center and neutralizing holes trapped in ONO regions above the junctions. We report, for the first time, the achieving of 10M P/E-cycle endurance in nitride storage flash memory. Excellent data retention capability is observed. This new flash memory uses no new high voltage device other than those already used for I/O and for normal programming and erase, and is completely compatible with normal fabrication processes.