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US 2013/0155767 A1Published application
Apparatuses and methods for sensing a phase-change test cell and determining changes to the test cell resistance due to thermal exposure
AssigneeMicron Technology, Inc.
InventorsJason Brand, Jason Snodgress
Life of this patent
Estimating the term…
Abstract
A phase change memory array may include at least one cell used to determine whether the array has been altered by thermal exposure over time. The cell may be the same or different from the other cells. In some embodiments, the cell is only read in response to an event. If, in response to that reading, it is determined that the cell has changed state or resistance, it may deduce whether the change is a result of thermal exposure. Corrective measures may then be taken.
Claims30
A method, comprising:
- sensing a characteristic of a phase change test cell that is configured to be more sensitive to thermal degradation than phase change memory cells of a phase change memory array;
- determining whether the sensed characteristic of the phase change test cell is within a tolerance range of an initial value;
- and
- refreshing the phase change memory array responsive to a determination that the sensed characteristic of the phase change test cell is outside the tolerance range of the initial value.
1 more element
A method, comprising:
- writing data to a phase change test cell that is configured to be more sensitive to thermal degradation than phase change memory cells of a phase change memory array, wherein the data is associated with an initial state of the phase change test cell;
- determining a state of the phase change test cell;
- and
- refreshing the phase change memory array responsive to the state of the phase change test cell changing from the initial state.
1 more element
An apparatus comprising:
- a phase change memory cell formed using a first fabrication method;
- a phase change test cell formed using a second fabrication method, wherein the phase change test cell is more sensitive to thermal degradation than the phase change memory cell, the phase change test cell configured in an initial state;
- and
- a controller coupled to the phase change memory cell and to the phase change test cell, the controller configured to determine whether the phase change test cell has changed from the initial state.
1 more element
An apparatus comprising:
- a phase change memory array;
- and
- a controller coupled to the phase change memory array, the controller configured to measure a respective resistance of selected phase change memory cells of the phase change memory array, the controller further configured to determine whether the respective resistance of a phase change memory cell of the selected phase change memory cells has changed from a respective initial resistance by more than a threshold amount.
A method, comprising:
- measuring a respective resistance of selected phase change memory cells of a phase change memory array;
- determining whether the respective resistance of a phase change memory cell of the selected phase change memory cells is within a tolerance range of a respective initial resistance;
- and
- refreshing the phase change memory array responsive to a determination that a count of the selected phase change memory cells having the respective measured resistance outside the tolerance range of the respective initial resistance exceeds a refresh required count.
1 more element
Dependencies are inferred from the claim text.