Thermally assisted MRAM including magnetic tunnel junction and vacuum cavity

• US 9,324,937 B1
• Filed: 03/24/2015
• Issued: 04/26/2016
• Est. Priority Date: 03/24/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation, Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: International Business Machines Corporation
• Inventors: Annunziata, Anthony J., Gapihan, Erwan
• Primary Examiner(s): Coleman, William
• Application Number:
  US14/666,363
• Time in Patent Office: 399 Days
• US Class Current: 1/1
• 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 thermally assisted magnetoresistive random access memory (TAS-MRAM) device includes a magnetic tunnel junction interposed between a first electrical contact and a second electrical contact. The TAS-MRAM device further includes a dielectric layer that is formed on an upper surface of the first electrical contact and that encapsulates the second electrical contact. The dialectic layer has at least one vacuum cavity between an adjacent outer wall of the magnetic tunnel junction and the dielectric layer.

Claims

1. A thermally assisted magnetoresistive random access memory (TAS-MRAM) device, comprising:

a magnetic tunnel junction interposed between a first electrical contact and a second electrical contact; and

a dielectric layer on an upper surface of the first electrical contact and encapsulating the second electrical contact, the dielectric layer having at least one vacuum cavity between an adjacent outer wall of the magnetic tunnel junction and the dielectric layer; and

at least one resistive strap interposed between the magnetic tunnel junction and at least one of the first electrical contact and the second electrical contact.

2. The TAS-MRAM device of claim 1, wherein the at least one vacuum cavity includes a first and second vacuum cavities surrounding the magnetic tunnel junction.

3. The TAS-MRAM device of claim 2, wherein a first vacuum cavity is between a first outer wall of the magnetic tunnel junction and the dielectric layer and a second vacuum cavity is between a second outer wall of the magnetic tunnel junction and the dielectric layer.

4. The TAS-MRAM device of claim 3, wherein the first and second vacuum cavities have a length extending between a respective outer wall and the dielectric layer, and a height extending between the first electrical contact and an upper surface of the magnetic tunnel junction.

5. The TAS-MRAM device of claim 4, wherein each of the first and second vacuum cavities are a free space having a pressure ranging from about 10⁻

3 torr (Torr) to about 10<sup>−

12</sup> Torr.

6. The TAS-MRAM device of claim 5, wherein the magnetic tunnel junction includes a tunnel barrier layer interposed between an opposing pair of ferromagnetic layers.

7. The TAS-MRAM device of claim 6, wherein the magnetic tunnel junction comprises magnesium oxide (MgO).

8. The TAS-MRAM device of claim 7, wherein the ferromagnetic layers comprise a ferromagnetic material selected from the group comprising cobalt (Co), iron (Fe) and nickel (Ni), and wherein a first ferromagnetic layer among the pair of ferromagnetic layers is a ferromagnetic storage layer, and a second ferromagnetic layer among the pair of ferromagnetic layers is a ferromagnetic sense layer.

9. The TAS-MRAM device of claim 1, wherein the at least one resistive strap comprises a thermally resistive material having a resistivity greater or equal to about 500 microohm centimeters (μ

Ω

·

cm).

10. A method of fabricating a thermally assisted magnetoresistive random access memory (TAS-MRAM) device, the method comprising:

forming a magnetic tunnel junction between a first electrical contact and a second electrical contact; and

performing a deposition process to deposit a dielectric layer on an upper surface of the first electrical contact and encapsulate the second electrical contact,

wherein at least one vacuum cavity is formed between an adjacent outer wall of the magnetic tunnel junction and the dielectric layer while simultaneously depositing the dielectric layer, and

wherein at least one resistive strap is interposed between the magnetic tunnel junction and at least one of the first electrical contact and the second electrical contact.

11. The method of claim 10, wherein the at least one vacuum cavity is formed in response to adjusting parameters of the deposition process such that the dielectric layer is non-conformally deposited and the at least one vacuum cavity is simultaneously formed between at least one sidewall of the magnetic tunnel junction and the dielectric layer.

12. The method of claim 11, wherein the parameters include at least one of a pressure, and a power ratio of a high power radio frequency (RF) with respect to a low power RF.

13. The method of claim 12, wherein the at least one vacuum cavity includes first and second vacuum cavities surrounding the magnetic tunnel junction.

14. The method of claim 13, wherein the first and second vacuum cavities have a length extending between a respective outer wall and the dielectric layer, and a height extending between the first electrical contact and an upper surface of the magnetic tunnel junction.

15. The method of claim 14, wherein each of the first and second vacuum cavities are a free space having a pressure ranging from about 10⁻

3 torr (Torr) to about 10<sup>−

12</sup> Torr.

16. The method of claim 15, wherein forming the magnetic tunnel junction includes forming a tunnel barrier layer between an opposing pair of ferromagnetic layers.

17. The method of claim 16, wherein the magnetic tunnel junction comprises magnesium oxide (MgO).

18. The method of claim 17, wherein the ferromagnetic layers comprise a ferromagnetic material selected from the group comprising cobalt (Co), iron (Fe) and nickel (Ni), and wherein a first ferromagnetic layer among the pair of ferromagnetic layers is a ferromagnetic storage layer, and a second ferromagnetic layer among the pair of ferromagnetic layers is a ferromagnetic sense layer.

19. The method of claim 18, wherein the at least one resistive strap comprises a thermally resistive material having a resistivity greater or equal to about 500 microohm centimeters (Ω

μ

·

cm).