Novel Ultra-Low Voltage and High-Speed Programming/Erasing Schemes for SONOS Flash Memory with Excellent Data Retention

A novel cell operation scheme featuring low voltage, high speed, and excellent data retention has been proposed for SONOS flash memory. First, in 1 bit/cell operation, program is achieved by a back-bias assisted hot hole injection, while erase is achieved by forward-bias assisted electron injection. For a thick tunnel oxide (50 Adeg), the ultra-low voltage (~5 V) and ultra-fast speed (<1musec) operation has been the record reported to date. On the other hand, a 2 bit/cell operation is also demonstrated, in which very good retention can be achieved in comparison to conventional operation schemes, e.g., CHE (channel hot electron) or BTB(Band-to-band) tunneling etc.