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United States Patent | 6,005,808 |
Sobek ,   et al. | December 21, 1999 |
A method and apparatus for reducing band-to-band currents during the erasure of a flash EEPROM memory cell is provided. The apparatus has a back biasing connection on the substrate at which a biasing voltage is applied during erasure of the flash EEPROM memory cell. The method of applying the biasing voltage to the back biasing connection during erasure of the flash EEPROM memory cell reduces band-to-band current between the source region and the substrate during erasure of the flash memory cell. This reduction provides for gate size reduction in flash memory cells without inducing detrimental short channel effects.
Inventors: | Sobek; Daniel (Portola Valley, CA); Thurgate; Timothy James (Sunnyvale, CA); Luning; Scott D. (San Francisco, CA); Chan; Vei-Han (San Jose, CA); Haddad; Sameer S. (San Jose, CA) |
Assignee: | Advanced Micro Devices, Inc. (Sunnyvale, CA) |
Appl. No.: | 993570 |
Filed: | December 18, 1997 |
Intern'l Class: | G11C 011/34 |
Field of Search: | 365/185.17,185.18,185.24,185.27 |
5077691 | Dec., 1991 | Haddad et al. | 365/185. |
5561620 | Oct., 1996 | Chen et al. | 365/218. |
5657271 | Aug., 1997 | Mori | 365/185. |
5790456 | Aug., 1998 | Haddad | 365/185. |
5790460 | Aug., 1998 | Chen et al. | 365/185. |
5844842 | Dec., 1998 | Seki et al. | 365/185. |
Foreign Patent Documents | |||
A2 597 722 | Nov., 1993 | EP. | |
WO98/47151 | Oct., 1998 | WO. |
Haddad, Sameer, et al., "Degradations Due to Hole Trapping in Flash Memory Cells", IEEE Electron Device Letters, vol. 10, No. 3, Mar. 1989, pp. 117-119. Haddad, Sameer, et al., "An Investigation of Erase-Mode Dependent Hole Trapping in Flash EEPROM Memory Cell", IEEE Electron Device Letters, vol. 11, No. 11, Nov., 1990, pp. 514-516. Chang, Chi, et al., "Drain-Avalanche and Hole-Trapping Induced Gate Leakage in Thin-Oxide MOS Devices", IEEE Electron Device Letters, vol. 9, No., 11, Nov. 1988, pp. 588-590. |
______________________________________ V.sub.B [volts] I.sub.S [.mu.A] ______________________________________ 0.0 124.70 0.5 71.291 1.0 50.474 1.5 33.859 2.0 19.034 ______________________________________