Variable resistance memory devices and erase verifying methods thereof
First Claim
1. An erase verifying method of a variable resistance memory device having a plurality of bit lines connected to a memory cell block, the method, comprising:
- applying a first voltage to a plurality of word lines connected to the memory cell block;
applying a second voltage less than the first voltage to the plurality of bit lines connected to the memory cell block;
sensing bit line currents flowing through the plurality of bit lines from the plurality of word lines;
comparing the sensed bit line currents with a reference current; and
determining that the memory cell block has been sufficiently erased by a first erase operation if each of the sensed bit line currents is less than the reference current,wherein the reference current is based on a product of the number of the plurality of word lines and an erase current, the erase current being a current flowing through a memory cell of the memory cell block.
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Abstract
An erase verifying method includes applying a first voltage to a plurality of word lines connected to a memory cell block, and applying a second voltage less than the first voltage to a plurality of bit lines connected to the memory cell block. The method includes sensing bit line currents flowing through the plurality of bit lines, and comparing the sensed bit line currents with a reference current. The method also includes determining that the memory cell block has been sufficiently erased by a first erase operation if each of the sensed bit line currents is less than the reference current.
31 Citations
12 Claims
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1. An erase verifying method of a variable resistance memory device having a plurality of bit lines connected to a memory cell block, the method, comprising:
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applying a first voltage to a plurality of word lines connected to the memory cell block; applying a second voltage less than the first voltage to the plurality of bit lines connected to the memory cell block; sensing bit line currents flowing through the plurality of bit lines from the plurality of word lines; comparing the sensed bit line currents with a reference current; and determining that the memory cell block has been sufficiently erased by a first erase operation if each of the sensed bit line currents is less than the reference current, wherein the reference current is based on a product of the number of the plurality of word lines and an erase current, the erase current being a current flowing through a memory cell of the memory cell block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An erase verifying method of a variable resistance memory device having a plurality of bit line groups connected to a memory cell block, each bit line group including more than one bit line, the method comprising:
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selecting one of the plurality of bit line groups; applying a first voltage to a plurality of word lines connected to the memory cell block; applying a second voltage less than the first voltage to the selected one of the plurality of bit line groups; applying the first voltage to unselected bit line groups; sensing bit line currents flowing through bit lines in the selected bit line group from the plurality of word lines; determining whether the memory cell block is sufficiently erased based on the sensed bit line currents, providing a reference current which is greater than a product of a number of the plurality of word lines and an erase current and less than a program current, the erase current being a current flowing through a first memory cell of the memory cell group; and comparing the sensed bit line currents with the reference current during the determining step. - View Dependent Claims (10, 11, 12)
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Specification