A channel-erasing 1.8-V-only 32-Mb NOR flash EEPROM with a bitline direct sensing scheme

A 1.8-V-only 32-Mb NOR flash EEPROM has been developed based on the 0.25-/spl mu/m triple-well double-metal CMOS process. A channel-erasing scheme has been implemented to realize a cell size of 0.49 /spl mu/m/sup 2/, the smallest yet reported for 0.25-/spl mu/m CMOS technology. A block decoder circuit with a novel erase-reset sequence has been designed for the channel-erasing operation. A bitline direct sensing scheme and a wordline boosted voltage pooling method have been developed to obtain high-speed reading operation at low voltage. An access time of 90 ns at 1.8 V has been realized.

[1]  Toru Tanzawa,et al.  Optimization of word-line booster circuits for low-voltage flash memories , 1999 .

[2]  J.C. Chen,et al.  A 2.7 V only 8 Mb/spl times/16 NOR flash memory , 1996, 1996 Symposium on VLSI Circuits. Digest of Technical Papers.

[3]  Y. Iyama,et al.  A 3.3 V-only 16 Mb flash memory with row-decoding scheme , 1996, 1996 IEEE International Solid-State Circuits Conference. Digest of TEchnical Papers, ISSCC.

[4]  S. Haddad,et al.  An investigation of erase-mode dependent hole trapping in flash EEPROM memory cell , 1990, IEEE Electron Device Letters.

[5]  Shinichi Kobayashi,et al.  A New Erasing And Row Decoding Scheme For Low Supply Voltage Operation 16Mb/64Mb Flash EEPROMs , 1991, 1991 Symposium on VLSI Circuits.

[6]  T. Jinbo,et al.  A 5 V-only 16 Mb flash memory with sector-erase mode , 1992, 1992 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[7]  S. Atsumi,et al.  A sampling weak-program method to tighten Vth-distribution of 0.5 V for low-voltage flash memories , 1999, 1999 Symposium on VLSI Circuits. Digest of Papers (IEEE Cat. No.99CH36326).

[8]  S. Yamada,et al.  A 5 V-only 0.6 mu m flash EEPROM with row decoder scheme in triple-well structure , 1992, 1992 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[9]  K. E. Kuijk,et al.  A precision reference voltage source , 1973 .