Memory cells having a plurality of resistance variable materials

1. A method of operating an array of resistance variable cells, comprising:

applying a first voltage to a resistance variable cell that includes a plurality of resistance variable materials to transition an active region of a first of the plurality of resistance variable materials from a crystalline phase to an amorphous phase,

wherein at least two of the plurality of resistance variable materials have a different respective thickness and each of the plurality of resistance variable materials are formed between a plug material and an electrode material,

wherein the cell includes a conductive material that contacts the electrode material and each of the plurality of resistance variable materials, and

wherein the cell includes a heater material that contacts the plug material and each of the plurality of resistance variable materials such that a current can flow through the heater material to heat the active region.

2. The method of claim 1 , including applying a second voltage to the resistance variable cell to transition an active region of a second of the plurality of resistance variable materials from a crystalline phase to an amorphous phase, wherein the first voltage has a different value than the second voltage.

3. The method of claim 2 , including applying a third voltage to the resistance variable cell to transition an active region of a third of the plurality of resistance variable materials from a crystalline phase to an amorphous phase, wherein the third voltage has a different value than the first voltage and the second voltage.

4. The method of claim 3 , wherein the first of the plurality of resistance variable materials has a respective thickness greater than the second of the plurality of resistance variable materials.

5. The method of claim 4 , wherein the second of the plurality of resistance variable materials has a respective thickness greater than the third of the plurality of resistance variable materials.

6. The method of claim 5 , wherein the first of the plurality of resistance variable materials has a different stoichiometry than the second of the plurality of resistance variable materials.

7. The method of claim 6 , wherein the second of the plurality of resistance variable materials has a different stoichiometry than the third of the plurality of resistance variable materials.

8. The method of claim 7 , wherein the first of the plurality of resistance variable materials has a different stoichiometry than the third of the plurality of resistance variable materials.

9. A method of operating an array of resistance variable cells, comprising:

applying a first voltage to a resistance variable cell that includes a plurality of resistance variable materials to program the cell from a first data state to a second data state,

wherein each of the plurality of resistance variable materials are formed between a plug material and an electrode material,

wherein the cell includes a conductive material that contacts the electrode material and each of the plurality of resistance variable materials, and

wherein the cell includes a heater material that contacts the plug material and each of the plurality of resistance variable materials.

10. The method of claim 9 , including applying a second voltage to the resistance variable cell to program the cell from the second data state to a third data state.

11. The method of claim 10 , wherein the second voltage is greater than the first voltage.

12. The method of claim 11 , including applying a third voltage to the resistance variable cell to program the cell from the third data state to a fourth data state.

13. The method of claim 12 , wherein the third voltage is greater than the second voltage.

14. A method of operating an array of resistance variable cells, comprising:

applying a first voltage to a resistance variable cell that includes a plurality of resistance variable materials to program the cell from a first binary data state to a second binary data state, wherein the first binary data state and the second binary data state are selected from a group comprising 00, 01, 10, and 11,

wherein a first of the plurality of resistance variable materials has a lesser respective thickness than a second of the plurality of resistance variable materials and each of the plurality of resistance variable materials is formed between a plug material and an electrode material,

wherein the cell includes a conductive material that contacts the electrode material and each of the plurality of resistance variable materials, and

wherein the cell includes a heater material that contacts the plug material and each of the plurality of resistance variable materials.

15. The method of claim 14 including applying a second voltage to the resistance variable cell to program the cell from the second binary data state to a third binary data state, wherein the third binary data state is selected from the group comprising 00, 01, 10, and 11.

16. The method of claim 15 including applying a third voltage to the resistance variable cell to program the cell from the third binary data state to a fourth binary data state, wherein the fourth binary data state is selected from the group comprising 00, 01, 10, and 11.

17. The method of claim 16 , wherein the plurality of resistance variable materials comprise at least one phase change material.

18. The method of claim 17 , wherein at least two of the plurality of resistance variable materials have different stoichiometries.

19. The method of claim 16 , wherein each of the plurality of resistance variable materials is in a crystalline phase when the first voltage is applied.

20. The method of claim 19 , wherein application of the third voltage results in each of the plurality of resistance variable materials being in an amorphous phase.