Process for creating a high density magnetic tunnel junction array test platform

• US 10,615,337 B2
• Filed: 04/18/2019
• Issued: 04/07/2020
• Est. Priority Date: 05/30/2018
• Status: Active Grant

• Current Assignee: Integrated Silicon Solution Incorporated (Uphill Investment Co.)
• Original Assignee: Spin Memory, Inc.
• Inventors: Manandhar, Pradeep, Shrivastava, Prachi, Pinarbasi, Mustafa, Boone, Thomas
• Primary Examiner(s): Slutsker, Julia
• Application Number:
  US16/388,774
• Publication Number:
  US 20190371997A1
• Time in Patent Office: 355 Days
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31051 Planarisation of the insulating layers H01L21/31058 takes precedence
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details

Abstract

A method for a photo and/or electron beam lithographic fabricating processes for producing a pillar array test device. The method includes receiving a wafer having a plurality of bit cells arranged in a grid and etching a plurality of bottom electrode traces to connect a plurality of bottom electrode pads in a centrally located bit cell to each of the bit cells in the grid. The method further includes fabricating an array of magnetic tunnel junction pillars onto each respective pad in the centrally located bit cell. The wafer is then planarized. The method further includes etching a plurality of top electrode traces to connect the plurality of magnetic tunnel junction pillars to each of the bit cells in the grid, and outputting the wafer for subsequent testing.

Claims

1. A device, comprising:

a grid of bit cells having a first density;

an array of pillars fabricated on a centrally located bit cell having a second density that is higher than the first density;

a bottom electrode layer comprising a plurality of bottom electrode traces connecting each of the memory cell pillars to a respective one of the grid of bit cells in a first fanout pattern; and

a top electrode layer comprising a plurality of top electrode traces connecting each of the memory cell pillars to a respective one of the grid of bit cells in a second fanout pattern.

2. The device of claim 1, wherein the plurality of top electrode traces connect to the bit cells in the grid using vias.

3. The device of claims 1, further comprising an array of metal posts located on top of the plurality of bottom electrode traces and operable to function as a base for the array of memory cell pillars.

4. The device of claim 1, wherein each of the plurality of bottom electrode traces comprises tantalum nitride.

5. The device of claim 1, wherein each of the plurality of top electrode traces comprises tantalum nitride.

6. The device of claim 1, wherein each of the grid of bit cells further comprises a CMOS driving transistor for individually addressing each of the memory cell pillars.

7. The device of claim 1, further comprising a silicon oxide passivation layer on the surface of the device.

23. The device of claim 1, wherein the memory cell pillars comprise magnetic tunnel junction pillars.

8. A device, comprising:

a grid of bit cells having a first density;

an array of memory cell pillars fabricated on a centrally located bit cell having a second density that is higher than the first density;

a bottom electrode layer comprising of a plurality of bottom electrode traces connecting each of the memory cell pillars to a respective one of the grid of bit cells in a first fanout pattern;

a top electrode layer comprising a plurality of top electrode traces connecting each of the memory cell pillars to a respective one of the grid of bit cells in a second fanout pattern; and

a silicon oxide passivation layer on the surface of the device.

9. The device of claim 8, wherein the plurality of top electrode traces connect to the bit cells in the grid using vias.

10. The device of claim 8, further comprising an array of metal posts located on top of the plurality of bottom electrode traces and function as a base for the array of memory cell pillars.

11. The device of claim 8, wherein each of the plurality of bottom electrode traces comprises tantalum nitride.

12. The device of claim 8, wherein each of the plurality of top electrode traces comprises tantalum nitride.

13. The device of claim 8, wherein each of the grid of bit cells further comprises a CMOS driving transistor for individually addressing each of the memory cell pillars.

24. The device of claim 8, wherein the memory cell pillars comprise magnetic tunnel junction pillars.

14. A device, comprising:

a grid of bit cells having a first density;

an array of memory cell pillars fabricated on a centrally located bit cell having a second density that is higher than the first density;

a bottom electrode layer comprising a plurality of bottom electrode traces connecting each of the memory cell pillars to a respective one of the grid of bit cells in a first fanout pattern;

a top electrode layer comprising a plurality of top electrode traces connecting each of the memory cell to a respective one of the grid of bit cells in a second fanout pattern; and

a CMOS driving transistor for individually addressing each of the memory cell pillars.

15. The device of claim 14, wherein the plurality of top electrode traces connect to the bit cells in the grid using vias.

16. The device of claim 14, wherein an array of metal posts are located on top of the plurality of bottom electrode traces and function as a base for the array of memory cell pillars.

17. The device of claim 14, wherein each of the plurality of bottom electrode traces comprises tantalum nitride.

18. The device of claim 14, wherein each of the plurality of top electrode traces comprises tantalum nitride.

19. The device of claim 14, further comprising a silicon oxide passivation layer on the surface of the device.

20. The device of claim 14, further comprising a plurality of contact points operable to interface with a CMOS testing device.

21. The device of claim 14, wherein the device comprises a pillar array test device.

22. The device of claim 14, wherein the memory cell pillars comprise magnetic tunnel junction pillars.