| US 7,573,750 B2 | ||
| High-speed verifiable semiconductor memory device | ||
| Noboru Shibata, Kawasaki (Japan) | ||
| Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan) | ||
| Filed on Sep. 15, 2008, as Appl. No. 12/210,585. | ||
| Application 12/210585 is a division of application No. 11/944874, filed on Nov. 26, 2007, granted, now 7,440,325. | ||
| Application 11/944874 is a continuation of application No. 11/682741, filed on Mar. 06, 2007, granted, now 7,310,269. | ||
| Application 11/682741 is a continuation of application No. 11/297467, filed on Dec. 09, 2005, granted, now 7,196,933. | ||
| Claims priority of application No. 2004-359029 (JP), filed on Dec. 10, 2004. | ||
| Prior Publication US 2009/0016117 A1, Jan. 15, 2009 | ||
| Int. Cl. G11C 16/04 (2006.01) | ||
| U.S. Cl. 365—185.22 [365/185.03] | 1 Claim |
| 1. A computer readable medium including computer executable instructions, wherein the instructions, when executed by a processor,
cause the processor to perform a method for a semiconductor memory device comprising:
carrying out a write operation with respect to a memory cell storing data using different threshold voltage levels, and making
no change in the threshold voltage levels in a next write operation when the memory cell reaches a predetermined first threshold
voltage level in a verify operation verifying whether or not the memory cell reaches the predetermined first threshold voltage
level;
increasing a change in threshold voltage level in the next write operation in order of a second threshold voltage level, a
third threshold voltage level, a fourth threshold voltage level, . . . , a k-th threshold voltage level (k≤i, k: a natural
number), when the threshold voltage level of the memory cell reaches an i-th threshold voltage level (i: a natural number
more than 3) lower than the first threshold voltage level; and
repeating the write operation and the verify operation until the first threshold voltage level is reached, the first threshold
voltage level>the second threshold voltage level>the third threshold voltage level> . . . >the i-th threshold voltage level.
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