Magnetic reader sensor with shield spacing improvement and better pin flop robustness

Patent metadata

Field	Value
Publication number	US-9799357-B1
Application number	US-201615345813-A
Country	US
Kind code	B1
Filing date	Nov 8, 2016
Priority date	Nov 8, 2016
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A MR sensor is disclosed with an antiferromagnetic (AFM) layer recessed behind a bottom shield to reduce reader shield spacing and improve pin related noise. Above the AFM layer is an AP2/AFM coupling layer/AP1 stack that extends from an air bearing surface to the MR sensor backside. The AP2 layer is pinned by the AFM layer, and the AP1 layer serves as a reference layer to an overlying free layer during a read operation. The AP1 and AP2 layers have improved resistance to magnetization flipping because back portions thereof have a full cross-track width “w” between MR sensor sides thereby enabling greater pinning strength from the AFM layer. Front portions of the AP1/AP2 layers lie under the free layer and have a track width less than “w”. The bottom shield may have an anti-ferromagnetic coupling structure. A process flow is provided for fabricating the MR sensor.

First claim

We claim:

1. A read head including a magnetoresistive (MR) sensor, comprising:
(a) a bottom shield with a top portion thereof having a top surface which extends from an air bearing surface (ABS) to a first height (h 1 ) at a first plane that is parallel to the ABS;
(b) a first stack of layers recessed behind the bottom shield top portion and having a front side at the first plane, the first stack includes at least an anti-ferromagnetic (AFM) layer that pins a magnetization direction in an overlying AP2 layer in a transverse direction, the first stack has a full cross-track width between two MR sensor sides, and a backside at a second plane that is parallel to the first plane;
(c) a second stack of layers including an AP2 magnetic layer formed on a top surface of the first stack and above the top surface of the bottom shield top portion, a middle first anti-ferromagnetic (AFM) coupling layer; and an upper AP1 magnetic layer with a top surface, the second stack comprises:
(1) a front portion with a front side at the ABS and wherein the second stack of layers has a first cross-track width (w 1 ) in a first region that extends a second height (h 2 ) from the ABS where h 2 <h 1 , and having the full cross-track width in a second region that adjoins a back end of the first region and extends to the first plane, wherein the first cross-track width (w 1 ) is less than the full cross-track width of the second region; and
(2) a back portion having the full cross-track width that adjoins a back end of the second region at the first plane and extends a third height distance to a backside at the second plane;

(d) a third stack of layers comprising a lower non-magnetic spacer, a middle free layer, and an upper capping layer each extending from the ABS to the second height, the non-magnetic spacer contacts a top surface of the second stack front portion, and the free layer has a track width less than or equal to the first cross-track width; and
(e) a top shield formed on the capping layer, a sense current is passed from the top shield through the second and third stack of layers in a perpendicular-to-plane direction to the bottom shield during a read operation.

2. The read head of claim 1 further comprising an isolation layer that adjoins a backside of the third stack of layers, and contacts the top surface of the AP1 magnetic layer from the second height to the second plane.

3. The read head of claim 2 wherein the isolation layer is made of one or more of Al 2 O 3 , TaOx, SiN, AlN, SiO 2 , MgO, and NiO.

4. The read head of claim 1 wherein the bottom shield top portion has an anti-ferromagnetically (AFM) coupled structure with a bottom magnetic layer, a middle AFM coupling layer, and an upper magnetic layer.

5. The read head of claim 1 wherein the first stack further comprises a first ferromagnetic layer on the AFM layer, the first ferromagnetic layer contacts a bottom surface of the AP2 magnetic layer and is ferromagnetically coupled thereto.

6. The read head of claim 1 wherein the first stack of layers further comprises a first ferromagnetic layer on the AFM layer, a second AFM coupling layer on the first ferromagnetic layer, and a second ferromagnetic layer on the second AFM coupling layer, the second ferromagnetic layer contacts a bottom surface of the AP2 magnetic layer and is ferromagnetically coupled thereto.

7. The read head of claim 1 wherein the non-magnetic spacer is one or more metal oxides, metal nitrides, or metal oxynitrides in a tunneling magnetoresistive (TMR) sensor configuration, or the non-magnetic spacer is a metal in a giant magnetoresistive (GMR) sensor configuration.

8. The read head of claim 1 further comprised of a second isolation layer on the two MR sensor sides and a magnetic layer adjoining a side of the second isolation layer that faces away from the MR sensor, the magnetic layer provides longitudinal biasing to the free layer.

9. The read head of claim 8 wherein the magnetic layer is comprised of a hard bias material that is CoPt, CoCrPt, or FePt, or is a junction shield comprised of an upper ferromagnetic layer, a lower ferromagnetic layer, and an antiferromagnetic coupling layer between the upper and lower ferromagnetic layers.

10. A read head including a magnetoresistive (MR) sensor, comprising:
(a) a bottom shield with a top portion thereof having a top surface which extends from an air bearing surface (ABS) to a first height (h 1 ) at a first plane that is parallel to the ABS;
(b) a first stack of layers recessed behind the bottom shield top portion and having a front side at the first plane, and including an antiferromagnetic (AFM) layer that pins a magnetization direction in an overlying AP2 layer in a transverse direction, and at least a first ferromagnetic (FM) layer above the AFM layer, the first stack has a full cross-track width between two MR sensor sides;
(c) a second stack of layers having an AP2 magnetic layer above the top surface of the bottom shield top portion and on the top surface of the first stack, a middle first anti-ferromagnetic coupling layer on the AP2 magnetic layer; and an upper AP1 magnetic layer with a top surface, the second stack comprises:
(1) a front portion with a front side at the ABS and wherein the second stack of layers has a first cross-track width in a first region that extends a second height (h2) from the ABS where h2<h1, and having a second region with a front side that adjoins a backside of the first region and wherein cross-track width increases with increasing distance from the ABS to a second cross-track width at the first plane; and
(2) a back portion having a full cross-track width that adjoins a back end of the second region at the first plane and extends to a second plane that is parallel to the ABS and is a third height from the first plane;

(d) a third stack of layers comprising a lower non-magnetic spacer, a middle free layer, and an upper capping layer each extending from the ABS to the second height, the non-magnetic spacer contacts a top surface of the second stack front portion, and the free layer has a track width less than or equal to the first cross-track width; and
(e) a top shield formed on the upper capping layer, a sense current is passed from the top shield through the second and third stack of layers in a perpendicular-to-plane direction to the bottom shield during a read operation.

11. The read head of claim 10 further comprising an isolation layer that is made of one or more of Al 2 O 3 , TaOx, SiN, AlN, SiO 2 , MgO, and NiO, and adjoins a backside of the third stack of layers, and contacts the top surface of the AP1 magnetic layer from the second height to the second plane.

12. The read head of claim 10 wherein the bottom shield top portion has an anti-ferromagnetically (AFM) coupled structure with a bottom magnetic layer, a middle AFM coupling layer, and an upper magnetic layer.

13. The read head of claim 10 wherein the first stack of layers further comprises a second anti-ferromagnetic (AFM) coupling layer on the first FM layer, and a second FM layer on the second AFM coupling layer, the second FM layer contacts a bottom surface of the AP2 magnetic layer and is ferromagnetically coupled thereto.

14. The read head of claim 10 wherein the non-magnetic spacer is one or more metal oxides, metal nitrides, or metal oxynitrides in a tunneling magnetoresistive (TMR) sensor configuration, or the non-magnetic spacer is a metal in a giant magnetoresistive (GMR) sensor configuration.

15. The read head of claim 10 wherein the MR sensor further comprises a seed layer formed on the top surface of the bottom shield top portion

Assignees

• Headway Tech Inc

Inventors

• Ding Ruhang
• Chye Yewhee
• Chen Wenyu
• Zhang Kunliang
• Li Min

Classifications

• G11B5/398

  Specially shaped layers · CPC title

• G11B5/3932

  Magnetic biasing films · CPC title

• G11B5/3912 Primary

  Arrangements in which the active read-out elements are transducing in association with active magnetic shields, e.g. magnetically coupled shields (G11B5/3916 takes precedence) · CPC title