A HIGH CAPACITIVE COUPLING RATIO (HICR) CELL FOR SINGLE 3 VOLT POWER-SUPPLY FLASH MEMORIES

A contact-less cell with high capacitive-coupling ratio (HiCR) of 0.8, which is programmed and erased by Fowler-Nordheim (F-N) tunneling, ha s been developed for single 3 V power-supply 64 Mbit and future flash memories. A 1.50 mum2 cell area is obtained by using 0.4 mum technolog y. The HiCR cell structure is realized by 1) self-aligned definition o f small tunneling regions underneath the floating-gate side wall and 2 ) an advanced rapid thermal process for 7.5 nm-thick tunnel-oxynitride . The internal-voltages used for PROGRAM and ERASE are + 8 V and + 12 V, respectively. The use of low positive internal-voltages results in reducing total process step numbers compared with reported memory cell s. The HiCR cell also realizes low power and fast random access with a single 3 V power-supply.