Non-volatile semiconductor memory device
First Claim
1. A non-volatile semiconductor memory device for performing data write and read operations in accordance with an input command, comprising:
- a memory cell array including a plurality of memory cells having three or more threshold voltage distributions in a single electric charge accumulation portion; and
a program sequence control circuit for causing the memory cell to store each piece of data included in a data set composed of a plurality of data values, in association with any of the three or more threshold voltage distributions, and shifting a threshold voltage distribution used for data storage in one direction when a rewrite operation is performed with respect to the data stored in the memory cell, thereby performing a data rewrite operation.
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Abstract
A memory cell transistor array is composed of a plurality of memory cells having three or more threshold voltage distribution states in a single electric charge accumulation portion. A program sequence control circuit associates each piece of data included in a data set composed of a plurality of data values with any threshold voltage distribution of the three or more threshold voltage distributions, to store the data in the memory cell, and when rewriting the data stored in the memory cell, shifting threshold voltage distributions used for data storage in one direction to perform the data rewrite operation.
27 Citations
35 Claims
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1. A non-volatile semiconductor memory device for performing data write and read operations in accordance with an input command, comprising:
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a memory cell array including a plurality of memory cells having three or more threshold voltage distributions in a single electric charge accumulation portion; and
a program sequence control circuit for causing the memory cell to store each piece of data included in a data set composed of a plurality of data values, in association with any of the three or more threshold voltage distributions, and shifting a threshold voltage distribution used for data storage in one direction when a rewrite operation is performed with respect to the data stored in the memory cell, thereby performing a data rewrite operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification