Nonvolatile memory device and method of driving the same
First Claim
1. A method of driving a nonvolatile memory device including a plurality of variable resistance memory cells, each of the plurality of variable resistance memory cells having a bit line coupled to the variable resistance memory cell and a column selection transistor coupled between the variable resistance memory cell and the bit line to receive a first control voltage being applied to a gate of the column selection transistor, the method comprising:
- setting the first control voltage at a first level;
changing a resistance of a selected memory cell from among the plurality of variable resistance memory cells by providing a write bias to the selected memory cell while setting the first control voltage;
determining whether the changed resistance of the selected memory cell enters into a desired resistance window;
changing, based on the determining step, the first control voltage to a second level that is different from the first level; and
changing the resistance of the selected memory cells by providing the write bias to the selected memory cell while changing the first control voltage.
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Abstract
A nonvolatile memory and a method of driving the same are provided, which adopt an improved write verify operation. The method of driving a nonvolatile memory device having variable resistance memory cells, bit lines coupled to the variable resistance memory cells, and column selection transistors coupled between the variable resistance memory cells and the bit lines to receive a first control voltage being applied to their gates, includes making the first control voltage at a first level, and changing a resistance of the variable resistance memory cells by providing a write bias to the variable resistance cells; verifying and reading whether the changed resistance enters into a specified resistance window; and changing the first control voltage to a second level that is different from the first level, and changing the resistance of the variable resistance memory cells by providing the write bias to the variable resistance memory cells.
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Citations
20 Claims
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1. A method of driving a nonvolatile memory device including a plurality of variable resistance memory cells, each of the plurality of variable resistance memory cells having a bit line coupled to the variable resistance memory cell and a column selection transistor coupled between the variable resistance memory cell and the bit line to receive a first control voltage being applied to a gate of the column selection transistor, the method comprising:
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setting the first control voltage at a first level; changing a resistance of a selected memory cell from among the plurality of variable resistance memory cells by providing a write bias to the selected memory cell while setting the first control voltage; determining whether the changed resistance of the selected memory cell enters into a desired resistance window; changing, based on the determining step, the first control voltage to a second level that is different from the first level; and changing the resistance of the selected memory cells by providing the write bias to the selected memory cell while changing the first control voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of driving a nonvolatile memory device including a plurality of variable resistance memory cells, each of the plurality of variable resistance memory cells having a bit line coupled to the variable resistance memory cell and column selection transistor coupled between the variable resistance memory cell and the bit lines to receive a first control voltage being applied to a gate of the column selection transistor, the method comprising:
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during a first write verify operation, writing write data by providing a write bias to a selected memory cell from among the plurality variable resistance memory cells; and during a second write verify operation, writing the write data by providing the write bias to the selected variable resistance memory cell, wherein a level of the first control voltage in the first write verify operation is different from a level of the first control voltage in the second write verify operation. - View Dependent Claims (9, 10, 11, 12)
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13. A nonvolatile memory device comprising:
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a plurality of variable resistance memory cells; bit lines coupled to the plurality of variable resistance memory cells, respectively; column selection transistors coupled between the plurality of variable resistance memory cells and the bit lines, respectively, each of the column selection transistors being configured to receive a first control voltage being applied to a gate of the column selection transistor; and a write circuit coupled to the bit lines configured perform a write operation by providing a write bias to a selected memory cell from among the plurality of variable resistance memory cells to write data, the write circuit being configured to perform the write operation through one or more successive write verify operations, wherein a level of the first control voltage in a previous write verify operation is different from a level of the first control voltage in a subsequent write verify operation. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification