Erasing non-volatile memory using individual verification and additional erasing of subsets of memory cells
First Claim
1. A method of erasing non-volatile storage, comprising:
- applying an erase voltage to a set of non-volatile storage elements while enabling erasing of each non-volatile storage element in said set, said set including a first subset of non-volatile storage elements and a second subset of non-volatile storage elements;
verifying whether said set is erased after applying said erase voltage by testing conduction through said set while applying a verify voltage to said first subset of non-volatile storage elements and applying a first voltage to said second subset of non-volatile storage elements, said first voltage is different from said verify voltage;
repeating said applying said erase voltage and verifying whether said set is erased until successfully verifying that said set is erased; and
applying said erase voltage to said set while inhibiting erasing of said first subset after successfully verifying that said set is erased.
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Accused Products
Abstract
A set of non-volatile storage elements is divided into subsets for erasing in order to avoid over-erasing faster erasing storage elements. The entire set of elements is erased until a first subset of the set of elements is verified as erased. The first subset can include the faster erasing cells. Verifying the first subset includes excluding a second subset from verification. After the first subset is verified as erased, they are inhibited from erasing while the second subset is further erased. The set of elements is verified as erased when the second subset is verified as erased. Verifying that the set of elements is erased can include excluding the first subset from verification or verifying both the first and second subsets together. Different step sizes are used, depending on which subset is being erased and verified in order to more efficiently and accurately erase the set of elements.
113 Citations
20 Claims
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1. A method of erasing non-volatile storage, comprising:
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applying an erase voltage to a set of non-volatile storage elements while enabling erasing of each non-volatile storage element in said set, said set including a first subset of non-volatile storage elements and a second subset of non-volatile storage elements; verifying whether said set is erased after applying said erase voltage by testing conduction through said set while applying a verify voltage to said first subset of non-volatile storage elements and applying a first voltage to said second subset of non-volatile storage elements, said first voltage is different from said verify voltage; repeating said applying said erase voltage and verifying whether said set is erased until successfully verifying that said set is erased; and applying said erase voltage to said set while inhibiting erasing of said first subset after successfully verifying that said set is erased. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of erasing non-volatile storage, comprising:
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applying an erase voltage to a set of non-volatile storage elements while enabling erasing of each non-volatile storage element of said set, said set including a first subset of non-volatile storage elements and a second subset of non-volatile storage elements; verifying whether said set is erased after applying said erase voltage by causing said second subset of non-volatile storage elements to be conductive and testing conduction through said set while applying a verify voltage to said first subset of non-volatile storage elements; repeating said applying said erase voltage and verifying whether said set is erased until successfully verifying that said set is erased; and applying said erase voltage to said set while inhibiting erasing of said first subset of non-volatile storage elements after successfully verifying that said set is erased. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of erasing non-volatile storage, comprising:
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applying an erase voltage to a block of non-volatile storage elements in communication with a set of word lines, said block including a plurality of sets of series-connected non-volatile storage elements; verifying whether said sets of non-volatile storage elements are erased after applying said erase voltage by applying a verify voltage to a first subset of said set of word lines and a first voltage to a second subset of said set of word lines, said first voltage is different from said verify voltage; repeating said applying and said verifying until all or a predetermined number of said sets of non-volatile storage elements are successfully verified as erased; and applying said erase voltage to said block of non-volatile storage elements while inhibiting erasing of non-volatile storage elements in communication with said first subset of word lines after successfully verifying that all or said predetermined number of said sets of non-volatile storage elements are erased. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification