Forming phase change memories
View Patent ↗Phase change memories may exhibit improved properties and lower cost in some cases by forming the phase change material layers in a planar configuration. A heater may be provided below the phase change material layers to appropriately heat the material to induce the phase changes. The heater may be coupled to an appropriate conductor.
1. A method comprising:
forming a planar phase change material layer;
forming a phase change material heater in thermal contact with said planar phase change material layer; and
coupling said phase change material heater to a conductor.
2. The method of claim 1 including forming phase change material over and substantially parallel to a semiconductor substrate.
3. The method of claim 1 including forming said phase change material layer over an insulator.
4. The method of claim 3 including forming a passage through said insulator.
5. The method of claim 4 including forming said phase change material heater in said passage.
6. The method of claim 5 including forming said conductor under said phase change material heater in said passage.
7. The method of claim 4 including using electron beam lithography to form said passage.
8. The method of claim 4 including forming a sidewall spacer in said passage.
9. The method of claim 6 including applying material to form said conductor in said passage.
10. The method of claim 9 including removing a portion of said material to form a space.
11. The method of claim 10 including forming said phase change material heater in said space.
12. The method of claim 1 including forming a conductor that is of substantially the same width as said phase change material heater.
13. The method of claim 1 including forming a conductor that is wider than said phase change material heater.
14. The method of claim 13 including forming said conductor, covering said conductor with an insulator, and forming a hole in said insulator.
15. The method of claim 14 including forming said phase change material heater in said hole.
16. The method of claim 15 including forming said hole using electron beam lithography.
17. The method of claim 15 including forming a sidewall spacer in said hole.
18. The method of claim 1 including forming a cup-shaped conductor.
19. The method of claim 18 including forming a ring-shaped heater.
20. The method of claim 19 including forming a first insulator, forming an opening in said first insulator, and forming a second insulator on the wall of said opening.
21. The method of claim 20 including covering said second insulator with a conductive material to form said conductor with a central passage.
22. The method of claim 21 including filling said passage with an insulator.
23. The method of claim 22 including removing a portion of said conductive material to form a ring-shaped space.
24. The method of claim 23 including filling said space with a material to form said phase change material heater.
25. The method of claim 1 including forming said phase change material layer over an insulator that has a thermal conductivity at least four times lower than oxide.
26. The method of claim 25 including forming said phase change material layer over a xerogel.
27. The method of claim 1 including forming a planar layer between said phase change material heater and said phase change material layer to heat said phase change material layer by providing a voltage drop.
28. The method of claim 27 including forming said planar layer of a material including carbon.