MULTIPLE LEVEL CELL PHASE CHANGE MEMORY DEVICE HAVING PRE-READ OPERATION RESISTANCE DRIFT RECOVERY, MEMORY SYSTEM EMPLOYING THE SAME, AND METHOD FOR READING THE MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method for reading a multiple level cell phase change memory device.

SOLUTION: The memory device comprises a plurality of memory cells, each memory cell comprising a memory cell material that has an initial resistance that is determined in response to an applied programming current in a programming operation, the resistance of the memory cell varying from the initial resistance over a time period following the programming operation, and each memory cell being connected to a conduction line of the memory device that is used to apply the programming current to program the resistance of the corresponding memory cell in the programming operation and that is used to apply a read current to read the resistance of the corresponding memory cell in a read operation. A modification circuit modifies the resistance of a memory cell of the plurality of memory cells selected for a read operation to return its resistance to near the initial resistance prior to a read operation of the memory cell.

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