A High Capacitive Coupling Ratio (HiCR) Cell for Single 3 Volt Power Supply Flash Memories

Kohji KANAMORI  Yosiaki S. HISAMUNE  Taishi KUBOTA  Yoshiyuki SUZUKI  Masaru TSUKIJI  Eiji HASEGAWA  Akihiko ISHITANI  Takeshi OKAZAWA  

IEICE TRANSACTIONS on Electronics   Vol.E77-C    No.8    pp.1296-1302
Publication Date: 1994/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on High Speed and High Density Multi Functional LSI Memories)
Category: Non-volatile Memory
F-N tunneling,  flash memory,  oxynitride,  low power supply,  

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A contact-less cell with high capacitive-coupling ratio (HiCR) of 0.8, which is programmed and erased by Fowler-Nordheim (F-N) tunneling, has been developed for single 3 V power-supply 64 Mbit and future flash memories. A 1.50 µm2 cell area is obtained by using 0.4 µm technology. The HiCR cell structure is realized by 1) self-aligned definition of 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 are8 V and 12 V, respectively. The use of low positive internal-voltages results in reducing total process step numbers compared with reported memory cells. The HiCR cell also realizes low power and fast random access with a single 3 V power-supply.