Optical determination of resistivity of phase change materials

1. A system comprising:

a non-contacting optical measurement instrument for obtaining a measurement of a phase-change material; and

a controller that determines a resistivity of the phase-change material based on the measurement,

wherein the phase-change material changes between an amorphous state and a crystalline state in response to temperature changes.

2. The system of claim 1 , wherein the measurement comprises a refractive index measurement.

3. The system of claim 1 , wherein the phase-change material is doped with nitrogen.

4. The system of claim 1 , wherein the phase-change material is doped with a material selected from a group consisting of oxygen, silicon, aluminum, and phosphorous.

5. The system of claim 1 , wherein the phase-change material comprises a chalcogen free material.

6. The system of claim 1 , wherein the phase-change material comprises a chalcogenide.

7. The system of claim 6 , wherein the chalcogenide is GeSbTe.

8. A system comprising:

a non-contacting optical measurement instrument for determining a refractive index of a doped phase-change material on a semiconductor wafer for fabricating phase-change memory devices; and

a controller that determines a resistivity of the doped phase-change material based on the refractive index,

wherein the doped phase-change material changes between an amorphous state and a crystalline state in response to temperature changes.

9. The system of claim 8 , wherein the non-contacting optical measurement instrument comprises a reflectometer.

10. The system of claim 8 , wherein the non-contacting optical measurement instrument comprises an ellipsometer.

11. The system of claim 8 , further comprising:

a database for correlating the refractive index to the resistivity.

12. The system of claim 8 , wherein the phase-change material comprises a chalcogenide.

13. The system of claim 8 , wherein the phase-change material comprises a chalcogen free material.

14. The system of claim 8 , wherein the doped phase-change material comprises a dopant selected from a group consisting of nitrogen, oxygen, silicon, aluminum, and phosphorous.

15. A system for determining resistivity comprising:

means for determining a refractive index of a phase-change material; and

means for determining a resistivity of the phase-change material based on the refractive index,

wherein the phase-change material changes between an amorphous state and a crystalline state in response to temperature changes.

16. The system of claim 15 , wherein the means for determining the refractive index comprises means for determining the refractive index of a phase-change material product sample.

17. The system of claim 15 , wherein the means for determining the refractive index comprises means for determining the refractive index of a doped chalcogenide phase-change material.

18. The system of claim 17 , wherein the means for determining the refractive index of the doped chalcogenide phase-change material comprises means for determining the refractive index of a nitrogen doped chalcogenide phase-change material.

19. The system of claim 17 , wherein the means for determining the refractive index of the doped chalcogenide phase-change material comprises means for determining the refractive index of nitrogen doped GeSbTe.

20. A method for determining resistivity, the method comprising:

obtaining an optical measurement of a phase-change material that chances between an amorphous state and a crystalline state in response to temperature changes; and

determining a resistivity of the phase-change material based on the optical measurement.

21. The method of claim 20 , wherein obtaining the optical measurement of the phase-change material comprises obtaining the optical measurement of a phase-change material doped with nitrogen.

22. The method of claim 20 , wherein obtaining the optical measurement comprises obtaining a reflectometer measurement.

23. The method of claim 20 , wherein obtaining the optical measurement comprises obtaining an ellipsometer measurement.

24. The method of claim 20 , wherein obtaining the optical measurement of the phase-change material comprises obtaining the optical measurement of a phase-change material comprising a chalcogenide.

25. A method for determining resistivity, the method comprising:

determining a refractive index of a doped phase-change material that changes between an amorphous state and a crystalline state in response to temperature changes; and

determining a resistivity of the phase-change material based on the refractive index.

26. The method of claim 25 , wherein determining the refractive index comprises determining the refractive index using reflectometry.

27. The method of claim 25 , wherein determining the refractive index comprises determining the refractive index using ellipsometry.

28. The method of claim 25 , wherein determining the resistivity comprises correlating the refractive index to a corresponding previously stored resistivity value.

29. The method of claim 25 , wherein determining the refractive index comprises determining the refractive index of a phase-change material product sample.

30. The method of claim 29 , further comprising:

determining a resistivity profile for the phase-change material product sample.