Method and apparatus for healing phase change memory devices

摘要

A first memory cell including a phase change material. The first memory cell is programmable to store one data value of a plurality of data values. The plurality of data values are represented by a plurality of non-overlapping ranges of resistance of the first memory cell. At least one testing pulse is applied to the first memory cell to establish a cell resistance of the first memory cell in an intermediate range of resistance, the intermediate range of resistance in between first and second adjacent ranges in the plurality of non-overlapping ranges of resistance representing the plurality of data values. After applying the at least one testing pulse to the first memory cell, it is determined whether to apply at least one healing pulse to repair the first memory cell, depending on relative values of (i) the cell resistance in the intermediate range of resistance and (ii) a reference resistance in the intermediate range of resistance.

主权项

1. A method of operating an array of memory cells, the memory cells including a phase change material, the memory cells programmable to store a plurality of data values, the plurality of data values represented by a plurality of non-overlapping ranges of resistance of the memory cells, the method comprising:
executing set and reset operations to memory cells in the array, the array including a first memory cell, to program resistances in the memory cells within the plurality of non-overlapping ranges of resistance representing the plurality of data values; and applying healing thermal energy to selected memory cells in the array after a predetermined number of set and/or reset cycles, wherein said applying healing thermal energy includes applying one or more current pulses having lower current amplitude than set and reset current pulses.