Patent ID: 7944740

Claim:
A method for programming a target memory cell in a phase change memory device to a target resistance, the phase change memory device including a plurality of memory cells, each memory cell storing binary data represented by at least two resistance states, the target memory cell belonging to the plurality of memory cells, the method comprising: retrieving a characterized lowest SET current and a corresponding SET resistance for the phase change memory device, the characterized lowest SET current being a minimum current amplitude of a SET pulse, the SET pulse being a current pulse required to change a phase change element of at least one memory cell in the phase change memory device from a fully amorphous state to a fully crystalline state which is the corresponding SET resistance; retrieving a characterized RESET current slope for the phase change memory device, the characterized RESET current slope comprising relative current amplitude values of a RESET pulse necessary for programming the plurality of memory cells to target resistances; calculating a first current amplitude for a RESET pulse based on the characterized lowest SET current, the corresponding SET resistance and the characterized RESET current slope for the phase change memory device; applying the RESET pulse to the target memory cell; measuring the resistance of the target memory cell after the RESET pulse is applied; and if the measured resistance of the target memory cell is substantially less than the target resistance, applying one or more additional RESET pulses to the target memory cell until the measured resistance is substantially equal to the target resistance.