Immunity of phase change material to disturb in the amorphous phase
View Patent ↗Disturb from the reset to the set state may be reduced by creating an amorphous phase that is substantially free of crystal nuclei when programming the reset state in a phase change memory. In some embodiments, this can be achieved by using a current or a voltage to program that exceeds the threshold voltage of the phase change memory element, but does not exceed a safe current voltage which would cause a disturb.
1. A method comprising:
reading a cell of a memory including a phase change memory element and an ovonic threshold switch using a refresh pulse followed by a read pulse to determine a threshold voltage of the cell to be read.
2. The method of claim 1 including determining whether the cell is on.
3. The method of claim 2 wherein if the cell is not on, using a refresh pulse greater than the cell's maximum expected threshold voltage.
4. The method of claim 3 including increasing a resulting current.
5. The method of claim 4 including, depending on a resistance that is determined, recording a detected state or forcing another refresh pulse and another read pulse.
6. A phase change memory comprising:
a phase change memory array including phase change memory elements and ovonic threshold switches; and
circuitry to read said array using a refresh pulse followed by a read pulse to determine the threshold voltage of a cell to be read.
7. The memory of claim 6 said circuitry to determine whether the cell is on.
8. The memory of claim 7 wherein, if the cell is not on, said circuitry to generate a refresh pulse greater than the cell's maximum expected threshold voltage.
9. The memory of claim 8 , said circuitry to increase a resulting current.
10. The memory of claim 9 , said circuitry to record a detected state or force another refresh pulse and another read pulse, depending on a determined resistance.