Magnetic read head with MR enhancements

Patent metadata

Field	Value
Publication number	US-9515253-B2
Application number	US-201514748872-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jan 2, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A TMR stack or a GMR stack, ultimately formed into a sensor or MRAM element, include insertion layers of Fe or iron rich layers of FeX in its ferromagnetic free layer and/or the AP1 layer of its SyAP pinned layer. X is a non-magnetic, metallic element (or elements) chosen from Ta, Hf, V, Co, Mo, Zr, Nb or Ti whose total atom percent is less than 50%. The insertion layers are between 1 and 10 angstroms in thickness, with between 2 and 5 angstroms being preferred and, in the TMR stack, they are inserted adjacent to the interfaces between a tunneling barrier layer and the ferromagnetic free layer or the tunneling barrier layer and the AP1 layer of the SyAP pinned layer in the TMR stack. The insertion layers constrain interdiffusion of B and Ni from CoFeB and NiFe layers and block NiFe crystalline growth.

First claim

What is claimed is:

1. A giant magnetoresistive (GMR) stack comprising:
a seed layer;
a pinning layer formed on said seed layer;
a synthetic antiparallel (SyAP) layer formed on said pinning layer and magnetically coupled thereto, wherein said SyAP layer is formed as an antiferromagnetically coupled pair of ferromagnetic layers denoted AP1 and AP2, said ferromagnetic layers being separated by a non-magnetic coupling layer, and wherein layer AP2 is formed on said pinning layer; and wherein
said AP1 layer incorporates a first plurality of insertion layers of the form Fe or FeX or multiple laminations thereof;
an electrically conducting, non-magnetic spacer layer formed on said AP1 layer;
a ferromagnetic free layer formed on said electrically conducting, non-magnetic spacer layer, said ferromagnetic free layer including a second plurality of insertion layers of the form Fe or FeX wherein X is one or more of the metallic, non-magnetic elements Ta, Hf, V, Mo, Zr, Nb or Ti, or multiple laminations of combinations thereof that are inserted to prevent interdiffusion and block crystallization; and
a capping layer formed on said ferromagnetic free layer.

2. A giant magnetoresistive (GMR) stack comprising:
a seed layer;
a pinning layer formed on said seed layer;
a synthetic antiparallel (SyAP) layer formed on said pinning layer and magnetically coupled thereto, wherein said SyAP layer is formed as an antiferromagnetically coupled pair of ferromagnetic layers denoted AP1 and AP2, said ferromagnetic layers being separated by a non-magnetic coupling layer, and wherein layer AP2 is formed on said pinning layer; and wherein
said AP1 layer incorporates a plurality of insertion layers of the form Fe or FeX wherein X is one or more of the metallic, non-magnetic elements Ta, Hf, V, Mo, Zr, Nb or Ti, or multiple laminations of combinations thereof that are inserted to block interdiffusion and to prevent crystallization;
a non-magnetic, electrically conducting spacer layer formed on said AP1 layer; and
a ferromagnetic free layer formed on said non-magnetic, electrically conducting spacer layer; and
a capping layer formed on said ferromagnetic free layer.

3. A giant magnetoresistive (GMR) stack comprising:
a seed layer;
a pinning layer formed on said seed layer;
a synthetic antiparallel (SyAP) layer formed on said pinning layer and magnetically coupled thereto, wherein said SyAP layer is formed as an antiferromagnetically coupled pair of ferromagnetic layers denoted AP1 and AP2, said ferromagnetic layers being separated by a non-magnetic coupling layer, and wherein layer AP2 is formed on said pinning layer;
a non-magnetic electrically conducting spacer layer formed on said AP1 layer; and
a ferromagnetic free layer formed on said non-magnetic electrically conducting spacer layer, wherein said ferromagnetic free layer includes a plurality of insertion layers of the form Fe or FeX wherein X is one or more of the metallic, non-magnetic elements Ta, Hf, V, Mo, Zr, or multiple laminations of combinations thereof that are inserted to block interdiffusion and prevent crystallization; and
a capping layer formed on said ferromagnetic free layer.

4. The GMR stack of claim 1 wherein the total atom percent of X is less than 50%.

5. The GMR stack of claim 2 wherein the total atom percent of X is less than 50%.

6. The GMR stack of claim 3 wherein the total atom percent of X is less than 50%.

7. The GMR stack of claim 1 wherein said first or second plurality of insertion layers of Fe or FeX are formed to a thickness between approximately 1 angstrom and 10 angstroms.

8. The GMR stack of claim 2 wherein said plurality of insertion layers of Fe or FeX are formed to a thickness between approximately 1 angstrom and 10 angstroms.

9. The GMR stack of claim 3 wherein said plurality of insertion layers of Fe or FeX are formed to a thickness between approximately 1 angstrom and 10 angstroms.

10. The GMR stack of claim 1 wherein said ferromagnetic free layer comprises bilayer structures of CoFeB/NiFe, or CoFe/NiFe, and wherein an insertion layer of the second plurality of insertion layers of Fe or FeX is inserted adjacent to said NiFe layer to constrain Ni interdiffusion and to block crystallization of NiFe, or is inserted next to the CoFeB layer to constrain interdiffusion of B atoms.

11. The GMR stack of claim 1 wherein said ferromagnetic free layer is formed as either of the sequential layers of CoFeB/NiFe/Fe or CoFeB/NiFe/FeX or CoFeB/FeX/NiFe or CoFeB/Fe/NiFe, whereby said second plurality of insertion layers of Fe or FeX is adjacent to said electrically conducting non-magnetic spacer layer and wherein said second plurality of insertion layers constrains B and Ni interdiffusion and blocks crystallization of NiFe.

12. The GMR stack of claim 2 wherein said ferromagnetic free layer comprises the bilayer structures CoFeB/NiFe, or CoFe/NiFe, and wherein an insertion layer of the plurality of insertion layers of Fe or FeX is inserted adjacent to said NiFe layer to constrain Ni interdiffusion and to block crystallization of NiFe, or is inserted next to the CoFeB layer to constrain interdiffusion of the B atoms.

13. The GMR stack of claim 2 wherein said ferromagnetic free layer is formed as either of the sequential layers CoFeB/NiFe/Fe or CoFeB/NiFe/FeX or CoFeB/FeX/NiFe or CoFeB/Fe/NiFe, whereby an insertion layer of the plurality of insertion layers Fe or FeX is adjacent to said tunneling barrier layer and wherein said insertion layer constrains B and Ni interdiffusion and blocks crystallization of NiFe.

14. The GMR stack of claim 3 wherein said ferromagnetic free layer is formed as either of the sequential layers of CoFeB/NiFe/Fe or CoFeB/NiFe/FeX or CoFeB/FeX/NiFe or CoFeB/Fe/NiFe, whereby an insertion layer or Fe or FeX is adjacent to said electrically conducting non-magnetic spacer layer and wherein said insertion layer constrains B and Ni interdiffusion and blocks crystallization of NiFe.

15. The GMR stack of claim 3 wherein said ferromagnetic free layer comprises bilayer structures of CoFeB/NiFe, or CoFe/NiFe, and wherein said insertion layer of the plurality of insertion layers of Fe or FeX is inserted adjacent to said NiFe layer to constrain Ni interdiffusion and to block crystallization of NiFe, or is inserted next to the CoFeB layer to constrain interdiffusion of the B atoms.

16. The GMR stack of claim 1 formed as a sensor device in either a top or bottom configuration.

17. The GMR stack of claim 1 formed as an MRAM device in either a top or bottom configuration.

18. The GMR stack of claim 2 formed as a sensor device in either a top or bottom configuration.

19. The GMR stack of claim 2 formed as an MRAM device in either a top or bottom configuration.

20. The GMR stack of claim 3 formed as a sensor device in either a top or bottom configuration.

21. The GMR stack of claim 3 formed as an MRAM device in either a top or bottom configuration.

Assignees

• Headway Tech Inc

Inventors

• Zhang Kunliang
• Wang Hui-Chuan
• Quan Junjie
• Chye Yewhee
• Li Min

Classifications

• H01F10/3254

  the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ] · CPC title

• H01F10/3295

  Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers · CPC title

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title

• H01F10/3272

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title