Phase change memory device and manufacturing method

• US 7,786,460 B2
• Filed: 01/09/2007
• Issued: 08/31/2010
• Est. Priority Date: 11/15/2005
• Status: Expired due to Fees

• Current Assignee: Macronix International Co., Ltd.
• Original Assignee: Macronix International Co., Ltd.
• Inventors: Lung, Hsiang Lan, Chen, Shih-Hung
• Primary Examiner(s): Nguyen; Dao H
• Application Number:
  US11/621,390
• Publication Number:
  US 20070109843A1
• Time in Patent Office: 1,330 Days
• Field of Search: 257/3, 257/4, 257/5, 257/E27.004, 257/E31.029, 257/E45.002, 438/92, 438/95, 438/96, 438/97
• US Class Current: 257/2
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 2213/79 Array wherein the access device being a transistor
• CPC Class Codes: H10B 63/30 comprising selection components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10N 70/063 by etching of pre-deposited switching material layers, e.g. lithography
• 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 70/823 adapted for essentially horizontal current flow, e.g. bridge type devices
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe
• CPC Class Codes: H10N 70/884 based on at least one element of group IIIA, IVA or VA, e.g. elemental or compound semiconductors compounds of sulfur, selenium or tellurium, e.g. chalcogenides H10N70/882; oxides or nitrides H10N70/883

Abstract

A phase change memory device comprises a photolithographically formed phase change memory cell having first and second electrodes and a phase change element positioned between and electrically coupling the opposed contact elements of the electrodes to one another. The phase change element has a width, a length and a thickness. The length, the thickness and the width are less than a minimum photolithographic feature size of the process used to form the phase change memory cell. The size of the photoresist masks used in forming the memory cell may be reduced so that the length and the width of the phase change element are each less than the minimum photolithographic feature size.

Claims

1. A phase change memory device comprising:

a memory cell access layer; and

a memory cell layer, operably coupled to the memory cell access layer, comprising a phase change memory cell, said memory cell comprising;

first and second opposed, spaced apart contact elements, respectively;

a phase change element positioned between the first and second contact elements and electrically coupling the first and second contact elements to one another;

the phase change element having a width, a length and a thickness, the length measured between the first and second contact elements and the width measured perpendicular to the length;

each of the length, the thickness and the width being less than a minimum lithographic feature size used to form the phase change memory cell; and

the first and second contact elements and the phase change element therebetween defining a memory cell arrangement extending generally parallel to the memory cell access layer.

2. The device of claim 1, wherein:

a first electrode comprises said first contact element;

a second electrode comprises said second contact element; and

the second electrode comprises a metal plug element connected to and spaced apart from the second contact element, the metal plug element extending generally perpendicular to the memory cell arrangement.

3. The device of claim 2, wherein the second contact element comprises a layer of TiN extending between the phase change element and the metal plug element.

4. The device of claim 1, wherein the memory cell access layer comprises a dielectric filler layer, and the phase change element is positioned directly opposite and adjacent to the dielectric filler layer.

5. The device of claim 1, wherein the phase change element is separated from the memory cell access layer by a dielectric material-filled region so the phase change element is completely and directly separated from the memory cell access layer by dielectric material.

6. The device of claim 5, wherein the phase change element is positioned spaced apart from the memory cell access layer by an oxide.

7. The device of claim 1, wherein the memory cell layer comprises an electrical contact enhancement material between the contact elements and the phase change element to enhance electrical contact between the contact elements and the phase change element.

8. The device of claim 7, wherein the contact enhancement material comprises TiN.

9. The device of claim 1, wherein the memory cell layer comprises a thermal insulation material between the contact elements and the phase change element to enhance thermal insulation between the contact elements and the phase change element.

10. The device of claim 1 wherein the memory cell layer comprises an electrical contact enhancement material and a thermal insulation material between the contact elements to enhance both thermal insulation and electrical contact between the contact elements and the phase change element.

11. The device of claim 1, wherein the phase change element has two solid phases that are reversibly inducible by a current.

12. The device of claim 1, wherein the phase change element has two solid phases that are reversibly inducible by a voltage applied across one or more of the contact elements.

13. The device of claim 1, wherein the phase change element has at least two solid phases that include a generally amorphous phase and a generally crystalline phase.

14. The device of claim 1, wherein the phase change element comprises memory material comprising an alloy including a combination of Ge, Sb, and Te.

15. The device of claim 1, wherein the phase change element comprises memory material comprising an alloy including a combination of two or more materials from the group of Ge, Sb, Te, Se, In, Ti, Ga, Bi, Sn, Cu, Pd, Pb, Ag, S, and Au.

16. The device of claim 1, wherein the first and second contact elements comprise an element selected from a group consisting of Ti, W, Mo, Al, Ta, Cu, Pt, Ir, La, Ni, and Ru and alloys thereof

17. The device of claim 1, wherein the minimum lithographic feature size is about 200 nm.

18. The device of claim 1, wherein the length is about 10 to 100 nm.

19. The device of claim 1, wherein the length is no more than about 60 nm.

20. The device of claim 1, wherein the width is about 10 to 50 nm.

21. The device of claim 1, wherein the width is no more than about 40 nm.

22. The device of claim 1, wherein the thickness is about 10 to 50 nm.

23. The device of claim 1, wherein the thickness is no more than about 20 nm thick.