Non-volatile memory device and related read method
First Claim
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1. A nonvolatile memory device, comprising:
- a memory cell array comprising a plurality of memory cells connected in series between a string selection transistor connected to a bit line and a ground selection transistor connected to a source line;
a voltage generator that provides read voltages to word lines of memory cells selected from among the plurality of memory cells during a read operation; and
a page buffer that senses a level of the bit line after applying a precharge voltage to the bit line in response to a bit line connection signal during the read operation,wherein the read voltages of the selected memory cells differ from each other according to their respective distances from the string selection transistor, and wherein a voltage level of the bit line connection signal of a selected memory cell located closest to the string selection transistor is set to be higher than a voltage level of the bit line connection signal for a selected memory cell located closest to the ground selection transistor.
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Abstract
A nonvolatile memory device comprises a memory cell array and a voltage generator. The memory cell array comprises a plurality of memory cells connected in series between a string selection transistor connected to a bit line and a ground selection transistor connected to a source line. The voltage generator provides read voltages to word lines of memory cells selected from among the plurality of memory cells during a read operation. The read voltages of the selected memory cells differ from each other according to their respective distances from the string selection transistor.
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Citations
14 Claims
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1. A nonvolatile memory device, comprising:
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a memory cell array comprising a plurality of memory cells connected in series between a string selection transistor connected to a bit line and a ground selection transistor connected to a source line; a voltage generator that provides read voltages to word lines of memory cells selected from among the plurality of memory cells during a read operation; and a page buffer that senses a level of the bit line after applying a precharge voltage to the bit line in response to a bit line connection signal during the read operation, wherein the read voltages of the selected memory cells differ from each other according to their respective distances from the string selection transistor, and wherein a voltage level of the bit line connection signal of a selected memory cell located closest to the string selection transistor is set to be higher than a voltage level of the bit line connection signal for a selected memory cell located closest to the ground selection transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of reading a nonvolatile memory device comprising a plurality of strings each comprising a plurality of memory cells connected in series between a string selection transistor connected to a bit line and a ground selection transistor connected to a source line, wherein the memory cells of the plurality of strings are organized in pages each connected to a common word line and blocks each comprising a plurality of pages, the method comprising:
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identifying a number of program/erase (P/E) cycles of a page in a block corresponding to an address received with a read instruction; performing a read operation by adjusting a read voltage applied to the page according to a distance between the page and the string selection transistor; and sensing a level of the bit line after applying a precharge voltage to the bit line in response to a bit line connection signal, wherein a voltage level of the bit line connection signal for a page located closest to the string selection transistor is set to be higher than a voltage level of the bit line connection signal for a page located closest to the ground selection transistor. - View Dependent Claims (10, 11)
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12. A method of reading a nonvolatile memory device comprising memory cells organized in blocks each comprising a plurality of pages, the method comprising:
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receiving a read instruction designating a selected block of memory cells; identifying a number of program/erase (P/E) cycles for a selected page within the selected block; adjusting a read voltage or a bit line connection signal for the selected page according to the number of P/E cycles and a distance between the selected page and a string selection transistor or a ground selection transistor; and performing a read operation on the selected page using the adjusted read voltage or bit line connection signal; wherein the bit line connection signal is decreased in proportion to the distance between the selected page and the string selection transistor, or increased in proportion to the distance between the selected page and the ground selection transistor. - View Dependent Claims (13, 14)
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Specification