Forming tapered lower electrode phase-change memories
View Patent ↗A phase-change memory may have a tapered lower electrode coated with an insulator. The coated, tapered electrode acts as a mask for a self-aligned trench etch to electrically separate adjacent wordlines. In some embodiments, the tapered lower electrode may be formed over a plurality of doped regions, and isotropic etching may be used to taper the electrode as well as part of the underlying doped regions.
1. A method comprising:
forming a conical structure over a substrate; and
using said conical structure as a mask to form a trench.
2. The method of claim 1 including forming a conical structure including a tapered electrode at the top of said conical structure.
3. The method of claim 1 including forming a plurality of layers in said conical structure of different conductivity types.
4. The method of claim 2 including forming layers in said conical structure of the same conductivity type but different doping levels.
5. The method of claim 1 including forming a phase-change material over said conical structure.
6. The method of claim 5 including forming an electrode over said phase-change material.
7. The method of claim 1 including covering said conical structure with an insulator.
8. The method of claim 7 including anisotropically etching said covered conical structure.
9. A phase-change memory comprising:
a substrate;
a conical structure formed over said substrate, said conical structure including an electrode;
a trench in said substrate self-aligned to said conical structure; and
a phase-change material in contact with said electrode.
10. The memory of claim 9 wherein said conical structure includes a plurality of layers of different conductivity types.
11. The memory of claim 10 wherein said conical structure includes a conductive line.
12. The memory of claim 9 including an insulator covering said conical structure.
13. The memory of claim 9 including two trenches self-aligned to said conical structure.
14. A phase change memory comprising:
a substrate;
a conical structure formed over said substrate, said conical structure including an electrode;
a material applied over said conical structure, a trench being formed in said material, said trench being self-aligned to said conical structure; and
a phase change memory in contact with said electrode.
15. The memory of claim 14 wherein said conical structure includes a plurality of layers of different conductivity types.
16. The memory of claim 15 wherein said conical structure includes a conductive line.
17. The memory of claim 14 including an insulator covering said conical structure.
18. The memory of claim 14 including two trenches self-aligned to said conical structure.