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US 8,797,805 B2Granted
Methods and apparatuses for determining threshold voltage shift
AssigneeMicron Technology, Inc.
InventorZhenlei Shen
Life of this patent
Estimating the term…
Abstract
Apparatuses and methods for determining threshold voltage shift are described. A number of methods for determining threshold voltage shift in memory cells include determining changes in threshold voltage for memory cells at each data state of a first number of data states by searching threshold voltage data of memory cells programmed to the first number of data states and determining changes in threshold voltage for memory cells at each data state of a second number of data states by searching threshold voltage data of memory cells programmed to the second number of data states within a range of threshold voltages, wherein the range is shifted from a previous range based on the changes in threshold voltage for memory cells programmed to the first number of data states.
Claims33
A method for determining threshold voltage shift in memory cells, comprising:
- determining changes in threshold voltage for memory cells at each data state of a first number of data states by searching threshold voltage data of memory cells programmed to the first number of data states having threshold voltages within a first range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the first number of data states during a first time period and during a second time period;
- and
- determining changes in threshold voltage for memory cells at each data state of a second number of data states by searching threshold voltage data of memory cells programmed to the second number of data states having threshold voltages within a second range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the second number of data states during the first time period and during the second time period, and wherein the second range is shifted from a previous range based on the changes in threshold voltage for memory cells programmed to the first number of data states and wherein the first number of data states are different data states than the second number of data states.
A method for operating an array of memory cells, comprising:
- determining changes in threshold voltage for memory cells programmed to each data state of a first number data states by searching threshold voltage data of memory cells programmed to the first number of data states having threshold voltages within a first range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the first number of data states during a first time period and during a second time period;
- estimating changes in threshold voltage for memory cells programmed to each data state of a second number data states based on the changes in threshold voltage for memory cells programmed to the first number of data states;
- and
- shifting a second range of threshold voltages associated with threshold voltage data of memory cells programmed to the second number of data states that is searched when determining changes in threshold voltage for memory cells programmed to each data state of the second number of data states, wherein the second range is shifted from a previous range based on the estimated changes in threshold voltage for memory cells programmed to each data state of the second number data states, wherein the first number of data states are different data states than the second number of data states.
1 more element
A method for determining threshold voltage shift in memory cells, comprising:
- determining a change in threshold voltage from a previous threshold voltage for memory cells programmed to each data state of a first number of data states by searching threshold voltage data of memory cells programmed to the first number of data states having threshold voltages within a first range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the first number of data states during a first time period and during a second time period;
- adjusting a second range of threshold voltages used to search threshold voltage data for threshold voltages of memory cells programmed to each data state of a second number of data states, wherein adjusting the second range of threshold voltages is based on the determined change in threshold voltage for memory cells programmed to each data state of the first number of data states;
- and
- determining a change in threshold voltage for memory cells programmed to each data state of the second number of data states by searching threshold voltage data of memory cells programmed to each data state of the second number of data states and that have threshold voltages within the adjusted second range, wherein the first number of data states are different data states than the second number of data states.
1 more element
An apparatus, comprising:
- an array of memory cells;
- and
- a controller operably coupled to the array and configured to:
- search threshold voltage data of memory cells programmed to a first number of data states having threshold voltages within a first range of threshold voltages to determine changes between a first time period and a second time period in threshold voltage of memory cells programmed to the first number of data states;
- and
- search threshold voltage data of memory cells programmed to a second number of data states having threshold voltages within a second range of threshold voltages that is shifted from a previous range based on changes in threshold voltage of memory cells programmed to the first number of data states to deterimine changes in threshold voltage for memory cells programmed to the second number of data states, wherein the first number of data states are different data states than the second number of data states.
3 more elements
An apparatus, comprising:
- an array of memory cells;
- and
- a controller operably coupled to the array and configured to:
- determine changes in threshold voltage for memory cells programmed to each of a first number data states by searching threshold voltage data of memory cells programmed to the first number of data states having threshold voltages within a first range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the first number of data states during a first time period and during a second time period;
- determine changes in threshold voltage for memory cells programmed to each of a second number data states by searching threshold voltage data of memory cells programmed to the second number of data states having threshold voltages within a second range of threshold voltages, wherein the threshold voltage data includes data associated with the memory cells at each data state of the second number of data states during the first time period and during the second time period, and wherein the second range is shifted from a previous range based on the changes in threshold voltage of memory cells programmed to the first number of data states, wherein the first number of data states are different data states than the second number of data states.
2 more elements
Dependencies are inferred from the claim text.