Nonvolatile semiconductor memory device which stores multi-value

Details Nonvolatile semiconductor memory device which stores multi-value Nonvolatile semiconductor memory device which stores multi-value

1997-04-30

1999-02-09

Nelms, David

Static information storage and retrieval

Floating gate

Multiple values

36518518, 36518521, 36518522, G11C 1134

Patent

active

058702180

ABSTRACT:
To enable one non-volatile memory cell to store four-value information, three different kinds of threshold voltages are serially applied to a word line in a verify operation to execute a write operation, the threshold voltages of the memory cell are controlled, and two-value (one-bit) information corresponding to the four-value (two-bit) information to be written are synthesized by a write data conversion circuit for each of the write operations carried out three times. In this way, the four-value (two-bit) information are written into one memory cell, and the memory capacity of the memory cell can be increased. In the information read operation, three different kinds of voltages are applied to a word line, three kinds of two-value (one-bit) information so read out are synthesized by a read conversion circuit and the memory information of the memory cell are converted to the two-bit information.

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Digest of Technical Papers, TP 2.1: A 3.3V 128Mb Multi-Level NAND Flash Memory for Mass Storage Applications, T. Jung, et al., ISSCC96/Session 2/Flash Memory/Paper TP 2.1, 1996 EEE International Solid State Circuits Conf.

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