Post-Fabrication Self-Aligned Initialization of Integrated Devices

• US 20120049144A1
• Filed: 08/31/2010
• Published: 03/01/2012
• Est. Priority Date: 08/31/2010
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: International Business Machines Corporation
• Inventors: Franceschini, Michele M., Karidis, John P.
• Granted Patent: US 8,575,008 B2
• Time in Patent Office: Days
• US Class Current: 257/3
• CPC Class Codes: H10N 70/021 Formation of switching materials, e.g. deposition of layers
• CPC Class Codes: H10N 70/063 by etching of pre-deposited switching material layers, e.g. lithography
• CPC Class Codes: H10N 70/20 Multistable switching devices, e.g. memristors
• 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 70/823 adapted for essentially horizontal current flow, e.g. bridge type devices
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/828 Current flow limiting means within the switching material region, e.g. constrictions
• CPC Class Codes: H10N 70/8413 adapted for resistive heating
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

Creating a localized region of material having a target chemical composition by defining an electrical circuit on a substrate, and depositing on the electrical circuit one or more layers of materials having one or more chemical compositions. An electrical current pulse is applied to the electrical circuit to create a self-aligned localized region having the target chemical composition. Applying the electrical current pulse causes a portion of the one or more layers of materials to be heated, resulting in the target chemical composition.

Claims

1. A method of creating a localized region of material having a target chemical composition, the method comprising:

defining an electrical circuit on a substrate;

depositing one or more layers of materials having one or more chemical compositions, the depositing on the electrical circuit; and

applying an electrical current pulse to the electrical circuit to create a self-aligned localized region having the target chemical composition, the applying an electrical current pulse causing a portion of the one or more layers of materials to be heated resulting in the target chemical composition.

2. The method of claim 1, wherein the applying an electrical current pulse causes an electrical current to flow from a first electrode to a second electrode, the electrical current passing through at least one of the layers of material.

3. The method of claim 1, wherein the one or more layers of materials comprise at least one layer of amorphous threshold switching material having high electrical resistivity at low electric field strength and substantially reduced electrical resistivity at electric field strengths above a threshold.

4. The method of claim 1, wherein the target chemical composition is a phase change material.

5. The method of claim 4, wherein the phase change material is a germanium-antimony-tellurium materials.

6. The method of claim 1, wherein the one or more layers of materials include a topmost layer that is a chemical resist, and the self-aligned localized region defines a region for sensitizing the chemical resist, the sensitizing occurring in response to an increase in temperature.

7. The method of claim 1, wherein an extent of the localized region is responsive to a geometry of the electrical circuit and to one or more of a magnitude and a duration of the electrical current pulse.

8. A method of defining an active region of a phase change memory (PCM) cell comprising:

depositing a first layer of material having a first chemical composition;

depositing a second layer of material having a second chemical composition on top of the first layer of material, and

applying an electrical current pulse to locally heat a region of the first layer of material and the second layer of material to cause at least one of an inter-diffusion and a liquid mixing of the first layer of material and the second layer of material, resulting in the PCM cell comprising a self-aligned region comprising a phase change material that is a mixture of the first chemical composition and the second chemical composition.

9. The method of claim 8, wherein the applying the electrical current pulse causes an electrical current to flow from a first electrode to a second electrode, the electrical current passing through at least the first layer of material.

10. The method of claim 8, wherein the first layer of material is an amorphous threshold switching material having high electrical resistivity at low electric field strength and substantially reduced electrical resistivity at electric field strengths above a threshold.

11. The method of claim 8, wherein the first layer of material is an insulator and the second layer of material is the phase change material, or the first layer of material is the phase change material and the second layer of material is an insulator.

12. The method of claim 8, wherein the PCM cell is characterized by a parallel path memory cell structure.

13. The method of claim 8, wherein the PCM cell is characterized by a vertical path memory cell structure.

14. A phase change memory (PCM) cell comprising:

a first electrode contacting a first layer of material having a first chemical composition;

a second layer of material having a second chemical composition; and

a second electrode contacting the first layer of material or the second layer of material;

the PCM cell configured for receiving at least one electrical current pulse flowing from the first electrode to the second electrode to locally heat a region of the first layer and the second layer to cause at least one of inter-diffusion and liquid mixing of the first layer of material and the second layer of material, resulting in a self-aligned region of phase change material having a chemical composition that is a mixture of the first chemical composition and the second chemical composition.

15. The PCM cell of claim 14, wherein the first layer of material is an amorphous threshold switching material having high electrical resistivity at low electric field strength and substantially reduced electrical resistivity at electric field strengths above a threshold.

16. The PCM cell of claim 14, wherein the first layer of material is an insulator and the second layer of material is the phase change material, or the first layer of material is the phase change material and the second layer of material is an insulator.

17. The PCM cell of claim 14, wherein the PCM cell is characterized by a parallel path memory cell structure.

18. The PCM cell of claim 14, wherein the PCM cell is characterized by a vertical path memory cell structure.

19. A design structure tangibly embodied in a machine readable medium for designing, manufacturing, or testing an integrated circuit, the design structure having a substantially planar surface, the design structure comprising:

a phase change memory (PCM) cell comprising;

a first electrode contacting a first layer of material having a first chemical composition;

a second layer of material having a second chemical composition; and

a second electrode contacting the first layer of material or the second layer of material;

the PCM cell configured for receiving at least one electrical current pulse flowing from the first electrode to the second electrode to locally heat a region of the first layer and the second layer to cause at least one of inter-diffusion and liquid mixing of the first layer of material and the second layer of material, resulting in a self-aligned region of phase change material having a chemical composition that is a mixture of the first chemical composition and the second chemical composition.

20. The design structure of claim 19, wherein the PCM cell is characterized by one of a parallel path memory cell structure and a vertical path memory cell structure.