Perpendicular magnetic anisotrophy free layers with iron insertion and oxide interfaces for spin transfer torque magnetic random access memory

Patent metadata

Field	Value
Publication number	US-9978935-B2
Application number	US-201615364409-A
Country	US
Kind code	B2
Filing date	Nov 30, 2016
Priority date	Jun 25, 2015
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A method of making a spin-torque transfer magnetic random access memory device (STT MRAM) device includes forming a tunnel barrier layer on a reference layer; forming a free layer on the tunnel barrier layer, the free layer comprising a cobalt iron boron (CoFeB) alloy layer and an iron (Fe) layer; and performing a sputtering process to form a metal oxide layer on the Fe layer.

First claim

What is claimed is:

1. A method of making a spin-torque transfer magnetic random access memory device (STT MRAM) device, the method comprising:
forming a tunnel barrier layer on a reference layer;
forming a free layer on the tunnel barrier layer, the free layer comprising a discrete cobalt iron boron (CoFeB) alloy layer and a discrete iron (Fe) layer arranged on the discrete CoFeB alloy layer, the Fe layer comprising at least 98 at. % Fe; and
performing a sputtering process to form a metal oxide layer on the Fe layer.

2. The method of claim 1 , wherein the Fe layer comprises at least 98 atomic % (at. %) Fe.

3. The method of claim 1 , wherein the Fe layer has a thickness in a range from about 0.2 to about 2 nanometers (nm).

4. The method of claim 1 , wherein the sputtering process is radiofrequency (RF) sputtering.

5. The method of claim 1 , wherein the tunnel barrier layer comprises magnesium oxide (MgO).

6. The method of claim 1 , wherein the metal oxide layer has a thickness in a range from about 0.2 to about 2 nm.

7. The method of claim 1 , wherein the CoFeB alloy layer has a thickness in a range from about 0.2 to about 2 nm.

8. The method of claim 1 , wherein the CoFeB alloy layer comprises boron (B) in an amount in a range from about 20 to about 30 at. %.

9. The method of claim 1 , wherein the CoFeB alloy layer comprises Fe in an amount in a range from about 20 to about 60 at. %.

10. The method of claim 1 , wherein the CoFeB alloy layer comprises cobalt (Co) in an amount in a range from about 20 to about 40 at. %.

11. The method of claim 2 , wherein the Fe layer comprises substantially pure Fe.

12. The method of claim 1 , wherein the sputtering process is RF sputtering.

13. The method of claim 1 , wherein the sputtering process comprises sputtering a metal oxide onto the Fe layer under a pressure in a range from about 0.1 to about 10 milli-Torr (mTorr).

14. The method of claim 1 , wherein the Fe layer comprises at least 99 at. % Fe.

15. The method of claim 1 , wherein the sputtering process comprises RF sputtering from an oxide target.

16. The method of claim 1 , wherein the discrete CoFeB alloy layer and the discrete Fe layer are ferromagnetically coupled and switch as a single entity under spin torqure currents.

17. The method of claim 12 , wherein the RF sputtering comprises sputtering a metal oxide onto the CoFeB alloy layer.

18. The method of claim 17 , wherein the metal oxide layer has a thickness in a range from about 0.2 to about 2 nm.

19. The method of claim 17 , wherein the metal oxide layer is MgO, tantalum oxide (TaOx), titanium oxide (TiOx), aluminum oxide (AlOx), magnesium titanium oxide (MgTiOx), or any combination thereof.

Assignees

• IBM

Inventors

• Hu Guohan

Classifications

• H01L43/10

  Electricity · mapped topic

• H01L43/12 Primary

  Electricity · mapped topic

• H01L43/02

  Electricity · mapped topic

• H01L43/08

  Electricity · mapped topic

• H10N50/85

  Materials of the active region · CPC title