Memory cell with memory material insulation and manufacturing method

• US 7,696,506 B2
• Filed: 06/27/2006
• Issued: 04/13/2010
• Est. Priority Date: 06/27/2006
• Status: Active Grant

• Current Assignee: Macronix International Co., Ltd.
• Original Assignee: Macronix International Co., Ltd.
• Inventors: Lung, Hsiang-Lan
• Primary Examiner(s): Parker; Kenneth A
• Assistant Examiner(s): Ho; Anthony
• Application Number:
  US11/426,771
• Publication Number:
  US 20070298535A1
• Time in Patent Office: 1,386 Days
• Field of Search: 257/4
• US Class Current: 257/4
• CPC Class Codes: H10B 63/30 comprising selection components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10N 70/026 by physical vapor deposition, e.g. sputtering
• CPC Class Codes: H10N 70/063 by etching of pre-deposited switching material layers, e.g. lithography
• 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 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/8616 Thermal insulation means
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

A memory cell, the memory cell includes first and second electrodes and a memory material element electrically coupling the first and second electrodes. The memory material element comprises a first memory material, such as GST, the first memory material having an electrical property that can be changed by the application of energy. A thermal insulating layer surrounds the memory material element. The thermal insulating layer comprises a second memory material. A dielectric layer separates the thermal insulating material from the memory material element. A method for making a thermally insulated memory cell device is also disclosed.

Claims

1. A memory cell, the memory cell being part of a memory cell device, comprising:

first and second electrodes;

a memory material element electrically coupling the first and second electrodes;

the memory material element comprising a first memory material, the first memory material comprising a phase change memory material;

a thermal insulating layer surrounding the memory material element;

the thermal insulating layer comprising a second memory material, the second memory material comprising a second phase change memory material comprising a chalcogenide; and

a dielectric layer separating and electrically insulating the thermal insulating layer from the memory material element.

2. The memory cell according to claim 1 wherein the first and second electrodes comprise portions contacting the memory material element, said portions comprising TiN.

3. The memory cell according to claim 1 wherein the first and second memory materials are the same memory material.

4. The memory cell according to claim 1 wherein the first memory material comprises GST.

5. The memory cell according to claim 1 wherein the second memory material is electrically isolated from at least one of the first and second electrodes.

6. The memory cell according to claim 1 wherein the dielectric layer electrically isolates the second memory material from at least one of the first and second electrodes.

7. The memory cell according to claim 1 wherein:

the first memory material has a thermal conductivity and a thermal expansion coefficient;

the second memory material has a thermal conductivity less than or equal to the thermal conductivity of the first memory material; and

the second memory material has a thermal expansion coefficient equal to or within 5% of the thermal expansion coefficient of the first memory material.

8. The memory cell according to claim 1 wherein:

the second memory material is at least a 1000 better thermal insulator than the dielectric layer; and

the thermal expansion coefficient of the second memory material is within 5% of the thermal expansion coefficient of the first memory material.

9. A memory cell, the memory cell being part of a memory cell device, comprising:

first and second electrodes;

a memory material element electrically coupling the first and second electrodes;

the memory material element comprising a first phase change memory material having a thermal conductivity and a thermal expansion coefficient;

a thermal insulating layer surrounding the memory material element;

the thermal insulating layer comprising a second phase change memory material having a thermal conductivity less than or equal to the thermal conductivity of the first phase change memory material and having a thermal expansion coefficient equal to or within 5% of the thermal expansion coefficient of the first phase change memory material; and

a dielectric layer separating the thermal insulating layer from the memory material element.

10. The memory cell according to claim 9 wherein the first and second electrodes comprise portions contacting the memory material element, said portions comprising TiN.

11. The memory cell according to claim 9 wherein the first and second phase change memory materials are the same material.

12. The memory cell according to claim 9 wherein the first phase change memory material comprises GST.

13. The memory cell according to claim 9 wherein the second phase change memory material is electrically isolated from at least one of the first and second electrodes.

14. The memory cell according to claim 9 wherein the dielectric layer electrically isolates the second phase change memory material from at least one of the first and second electrodes.

15. A memory cell, the memory cell being part of a memory cell device, comprising:

first and second electrodes;

a memory material element electrically coupling the first and second electrodes;

the memory material element comprising a first phase change memory material having a thermal conductivity and a thermal expansion coefficient;

a thermal insulating layer surrounding the memory material element;

the thermal insulating layer comprising a second phase change memory material having a thermal expansion coefficient within 5% of the thermal expansion coefficient of the first phase change memory material; and

a dielectric layer separating the thermal insulating layer from the memory material element,

wherein the second phase change material is at least a 10% better thermal insulator than the dielectric layer.

16. The memory cell according to claim 15 wherein the first and second electrodes comprise portions contacting the memory material element, said portions comprising TiN.

17. The memory cell according to claim 15 wherein the first and second phase change memory materials are the same material.

18. The memory cell according to claim 15 wherein the first phase change memory material comprises GST.

19. The memory cell according to claim 15 wherein the second phase change memory material is electrically isolated from at least one of the first and second electrodes.

20. The memory cell according to claim 15 wherein the dielectric layer electrically isolates the second phase change memory material from at least one of the first and second electrodes.

21. A memory cell, the memory cell being part of a memory cell device, comprising:

first and second electrodes;

a memory material element electrically coupling the first and second electrodes;

the memory material element comprising a first programmable phase change memory material;

a thermal insulating layer completely surrounding the memory material element;

the thermal insulating layer comprising a second programmable phase change memory material; and

a dielectric layer completely separating the thermal insulating layer from the memory material element.

22. The memory cell according to claim 21 wherein the first and second electrodes comprise portions contacting the memory material element, said portions comprising TiN.

23. The memory cell according to claim 21 wherein the first and second phase change memory materials are the same material.

24. The memory cell according to claim 21 wherein the first phase change memory material comprises GST.

25. The memory cell according to claim 21 wherein the second phase change memory material is electrically isolated from at least one of the first and second electrodes.

26. The memory cell according to claim 21 wherein the dielectric layer electrically isolates the second phase change memory material from at least one of the first and second electrodes.

27. The memory cell according to claim 21 wherein:

the first phase change memory material has a thermal conductivity and a thermal expansion coefficient;

the second phase change memory material has a thermal conductivity less than or equal to the thermal conductivity of the first phase change memory material; and

the second phase change memory material has a thermal expansion coefficient equal to or within 5% of the thermal expansion coefficient of the first phase change memory material.

28. The memory cell according to claim 21 wherein:

the second phase change memory material is at least a 10% better thermal insulator than the dielectric layer; and

the thermal expansion coefficient of the second phase change memory material is within 5% of the thermal expansion coefficient of the first phase change memory material.