IP Library › Granted Patent US 6,881,603
Granted Patent B2
US 6,881,603 · App. 10/299,291 · Granted Apr 19, 2005

Phase change material memory device

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Quick Facts
Patent No.
US 6,881,603
App. No.
10/299,291
Granted
Apr 19, 2005
Kind
B2
Abstract

A phase change memory with a very limited area of contact between the lower electrode and the phase change material may be formed by defining a closed geometric structure for the lower electrode. The lower electrode may then be covered. The covering may then be opened in a very narrow strip extending across the closed geometric shape using phase shift masking. A phase change material may be formed in the opening. Because the opening effectively bisects the closed geometric structure of the lower electrode, two very small contact areas may be created for contacting the lower electrode to the phase change material.

Claims (24)

1. A method comprising:

forming an electrode having a closed geometric shape;

covering said electrode;

forming an opening through said covering which bisects said closed geometric shape at two different locations; and

forming, in said opening, a phase change material layer contacting an exposed portion of said electrode.

2. The method of claim 1 wherein forming an electrode having a closed geometric shape includes forming an electrode having a flat bottom and an upstanding side wall coupled to said flat bottom.

3. The method of claim 2 including electrically coupling said flat bottom to a buried conductive layer.

4. The method of claim 2 including forming said closed geometric shape in said upper end of said side wall.

5. The method of claim 2 wherein covering said electrode includes filling the interior of said closed geometric shape.

6. The method of claim 1 including planarizing after covering said electrode.

7. The method of claim 1 including using phase shift masking to form said opening which bisects said closed geometric shape at two different locations.

8. The method of claim 7 including contacting said phase change material to said electrode at only one of said locations.

9. The method of claim 7 including using phase shift masking to form an elongate opening across said closed geometric shape.

10. The method of claim 1 including forming a can-shaped electrode having a substantially circular upper edge and exposing said upper edge using phase shift masking to form an opening that bisects said circular upper edge.

11. A method comprising:

forming an electrode;

covering said electrode;

masking to form an opening through said covering to expose two spaced portions of said electrode, said portions being unconnected within said opening; and

forming, in said opening, a phase change material layer contacting said exposed portions of said electrode.

12. The method of claim 11 including forming said opening using phase shift masking.

13. The method of claim 11 including forming an electrode having a closed geometric shape.

14. The method of claim 13 including forming an opening that bisects said closed geometric shape at two locations.

15. The method of claim 14 including contacting said phase change material to said electrode in only one of said locations.

16. The method of claim 14 including using said phase shift masking to form an elongate opening across said closed geometric shape.