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US 5,329,488 AGranted
Nonvolatile semiconductor memory device with redundancy circuit
AssigneeNEC Corporation
InventorKiyokazu Hashimoto
Life of this patent
Estimating the term…
Abstract
A nonvolatile semiconductor memory device for use as a flash EEPROM includes a plurality of sectors each comprising a plurality of main memory cell regions each composed of a matrix of nonvolatile memory cells and at least one redundant memory cell region composed of a matrix of nonvolatile memory cells. When one of said nonvolatile memory cells in any one of the sectors is found defective and is selected by addressing, it is replaced with one of the nonvolatile memory cells in the redundant memory cell region.
Claims7
A nonvolatile semiconductor memory device comprising:
- a plurality of sectors each comprising a plurality of main memory cell regions each composed of a matrix of nonvolatile memory cells;
- control means for writing data in, erasing data from, and reading data from said nonvolatile memory cells in each of said sectors;
- at least one redundant memory cell region composed of a matrix of nonvolatile memory cells;
- replacing means for replacing any one of said nonvolatile memory cells which is selected by addressing in any one of said sectors and when the addressed cell is found to be defective, said replacing being with one of the nonvolatile memory cells and in said at least one redundant memory cell region;
- and
- voltages of sources of memory cells constituting each sector being controlled and driven by a circuit means;
- sources of memory cells in said redundant memory cell regions being controlled and driven by an independent circuit means which is other than said circuit means which controls and drives the voltages of the sources of memory cells constituting each sector.
4 more elements
Dependencies are inferred from the claim text.