PHASE-CHANGE MEMORY ELEMENT AND METHOD FOR FABRICATING THE SAME

• US 20100230653A1
• Filed: 03/16/2009
• Published: 09/16/2010
• Est. Priority Date: 03/16/2009
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chen, Frederick T.
• Granted Patent: US 7,888,155 B2
• Time in Patent Office: Days
• US Class Current: 257/4
• CPC Class Codes: H10N 70/068 by processes specially adapted for achieving sub-lithographic dimensions, e.g. using spacers
• CPC Class Codes: H10N 70/231 based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/8265 on sidewalls of dielectric structures, e.g. mesa-shaped or cup-shaped devices
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

A phase-change memory element is provided. The phase-change memory element includes: a first electrode formed on a substrate; a first dielectric layer, with an opening, formed on the first electrode, wherein the opening exposes a top surface of the first electrode; a pillar structure formed directly on the first electrode within the opening; an inner phase-change material layer surrounding the pillar structure, directly contacting the first electrode; a second dielectric layer surrounding the inner phase-change material layer; an outer phase-change material layer surrounding the second dielectric layer; a phase-change material collar formed between the second dielectric layer and the first electrode, connecting the inner phase-change material layer with the outer phase-change material layer; and a second electrode formed directly on the pillar structure, directly contacting the top surface of the inner phase-change material layer.

Claims

1. A phase-change memory element, comprising

a first electrode formed on a substrate;

a first dielectric layer, with an opening, formed on the first electrode, wherein the opening exposes a top surface of the first electrode;

a pillar structure formed directly on the first electrode within the opening;

an inner phase-change material layer surrounding the pillar structure, directly contacting the first electrode;

a second dielectric layer surrounding the inner phase-change material layer;

an outer phase-change material layer surrounding the second dielectric layer;

a phase-change material collar formed between the second dielectric layer and the first electrode, connecting the inner phase-change material layer with the outer phase-change material layer; and

a second electrode formed directly on the pillar structure, directly contacting the top surface of the inner phase-change material layer.

2. The phase-change memory element as claimed in claim 1, wherein the inner phase-change material layer, the second dielectric layer, and the outer phase-change material layer are concentric with the pillar structure.

3. The phase-change memory element as claimed in claim 1, wherein the top surface of the pillar structure and the top surface of the first dielectric layer are coplanar.

4. The phase-change memory element as claimed in claim 1, wherein the top surface of the inner phase-change material layer, the top surface of the outer phase-change material layer, and the top surface of the second dielectric layer are coplanar.

5. The phase-change memory element as claimed in claim 1, wherein the top surface of the inner phase-change material layer and the top surface of the pillar structure are coplanar.

6. The phase-change memory element as claimed in claim 1, wherein the first electrode and the second electrode respectively comprise Al, W, Mo, Ti, TiN, TiAlN, TiW or TaN.

7. The phase-change memory element as claimed in claim 1, wherein the pillar structure consists of a top pillar and a bottom pillar, wherein the top pillar directly contacts the second electrode and the bottom pillar directly contacts the first electrode.

8. The phase-change memory element as claimed in claim 7, wherein the top pillar is made of conductive material comprising Al, W, Mo, Ti, TiN, TiAlN, TiW or TaN.

9. The phase-change memory element as claimed in claim 7, wherein the top pillar is made of dielectric material that is different from that of the bottom pillar.

10. The phase-change memory element as claimed in claim 7, wherein the bottom pillar comprise dielectric material.

11. The phase-change memory element as claimed in claim 1, wherein the inner phase-change material layer, the outer phase-change material layer and the phase-change material collar are formed by the same process and made by the same material.

12. The phase-change memory element as claimed in claim 1, wherein the bottom surface of the inner phase-change material layer, the bottom surface of the outer phase-change material layer, and the bottom surface of the phase-change material collar are coplanar.

13. The phase-change memory element as claimed in claim 1, wherein the second electrode does not directly contact with the outer phase-change material layer.

14. The phase-change memory element as claimed in claim 1, wherein the diameter of the opening is between 15-70 nm.

15. The phase-change memory element as claimed in claim 1, wherein the diameter of the pillar structure is between 5-20 nm.

16. The phase-change memory element as claimed in claim 1, wherein the width of the inner phase-change material layer is between 2-10 nm.

17. The phase-change memory element as claimed in claim 1, wherein the width of the outer phase-change material layer is between 2-10 nm.

18. The phase-change memory element as claimed in claim 1, wherein the width of the second dielectric layer is between 1-28.5 nm.

19. A method for fabricating a phase-change memory element, comprising:

providing a first electrode on the substrate;

forming a first dielectric layer with an opening on the first electrode, wherein the opening exposes a top surface of the first electrode;

conformally forming a second dielectric layer on the first dielectric layer, covering the side walls and the bottom surface of the opening;

forming a non-phase-change material layer on the second dielectric layer as a blanket film;

performing a first planarizing process to remove a portion of the second dielectric layer and the non-phase-change material layer with the first dielectric layer acting as a stop layer, leaving a non-phase-change material pillar and a remaining second dielectric layer;

etching the remaining second dielectric layer with the non-phase-change material pillar as an etching mask, leaving a second dielectric pillar, wherein the non-phase-change material pillar and the second dielectric pillar comprises a pillar structure;

conformally forming a phase-change material layer on the first dielectric layer, the exposed top surface of the first electrode and the pillar structure, defining a collar opening;

forming a third dielectric layer on the phase-change material layer as a blanket film, filling the collar opening;

performing a second planarizing process to remove a portion of the phase-change material layer and the third dielectric layer with the first dielectric layer acting as a stop layer, leaving an inner phase-change material layer surrounding the pillar structure, a remaining third dielectric layer surrounding the inner phase-change material layer, an outer phase-change material layer surrounding the remaining third dielectric layer, and a phase-change material collar formed directly below the remaining third dielectric layer and connecting the inner phase-change material layer and the outer phase-change material layer; and

forming a second electrode formed directly on the pillar structure, directly contacting the top surface of the inner phase-change material layer.

20. The method as claimed in claim 19, wherein the non-phase-change material layer is made of conductive material comprising Al, W, Mo, Ti, TiN, TiAlN, TiW or TaN.

21. The method as claimed in claim 19, wherein the non-phase-change material layer is made of dielectric material that is different from that of the second dielectric layer.