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

Patent metadata

Field	Value
Publication number	US-10157634-B2
Application number	US-201715790342-A
Country	US
Kind code	B2
Filing date	Oct 23, 2017
Priority date	Nov 8, 2016
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A process flow is disclosed for forming a MR sensor having an antiferromagnetic (AFM) layer recessed behind a bottom shield to reduce reader shield spacing and improve pin related noise. An AP 2 /AFM coupling layer/AP 1 stack that extends from an air bearing surface to the MR sensor backside is formed above the AFM layer. The AP 2 layer is pinned by the AFM layer, and the AP 1 layer serves as a reference layer to an overlying free layer during a read operation. The AP 1 and AP 2 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 AP 1 /AP 2 layers lie under the free layer and have a track width less than “w”. The bottom shield may have an anti-ferromagnetic coupling structure.

First claim

We claim:

1. A method of fabricating a magnetoresistive (MR) sensor wherein an antiferromagnetic (AFM) layer is recessed a certain distance from an air bearing surface (ABS) in order to reduce reader shield spacing, comprising:
(a) providing a bottom shield and sequentially forming a first stack of layers thereon, the first stack comprises a lower AFM layer, and a first ferromagnetic (FM) layer on the lower AFM layer;
(b) removing a front portion of the first stack between a front plane that is an eventual air bearing surface (ABS) and a first plane that is parallel to the front plane and a first height (h 1 ) therefrom thereby forming a first opening, and filling the first opening with a magnetic material to form a top portion of the bottom shield, and a seed layer with a top surface above the bottom shield top portion;
(c) depositing a second stack of layers on the top surface of the first stack and on the seed layer top surface, the second stack has a front portion between the front plane and first plane, and a back portion behind the first plane and is comprised of an AP 2 layer with a first magnetization that is pinned by the AFM layer, a first AFM coupling layer on the AP 2 layer, and an AP 1 layer on the first AFM coupling layer, the AP 1 layer has a magnetization in a transverse direction that is opposite to the first magnetization;
(d) depositing a third stack of layers on the second stack and with a front side at the front plane, the third stack comprises a non-magnetic spacer on the AP 1 layer, a free layer on the non-magnetic spacer, and an upper capping layer;
(e) removing a back portion of the third stack thereby forming a second opening to expose a top surface of the AP 1 layer, each of the third stack layers has a backside that is a second height (h 2 ) from the front plane where h 2 <h 1 ;
(f) filling the second opening with a first isolation layer; and
(g) removing a portion of the second and third stacks to form a third opening on each side of a center plane that is orthogonal to the front plane, the third openings are separated by a first cross-track width and expose the top portion of the bottom shield on each side of the center plane.

2. The method of claim 1 wherein the first stack of layers further comprises a second AFM coupling layer on the first FM layer, and a second ferromagnetic (FM) layer on the second AFM coupling layer, the second FM layer is ferromagnetically coupled to the back portion of the AP 2 layer.

3. The method of claim 2 wherein the first and second FM layers, the AP 1 layer, and the AP 2 layer have a transverse magnetization that is orthogonal to the front plane, and the free layer has a magnetization in a longitudinal direction that is parallel to the front plane in the absence of an external magnetic field.

4. The method of claim 1 wherein the bottom shield top portion is comprised of a single magnetic layer or is an antiferromagnetically coupled structure comprised of a lower magnetic layer formed on the bottom shield, a second AFM coupling layer on the lower magnetic layer, and an upper magnetic layer.

5. The method of claim 1 wherein the first isolation layer is one or more of Al 2 O 3 , TaOx, SiN, AIN, SiO 2 , MgO, and NiO.

6. The method of claim 1 further comprised of sequentially depositing a second isolation layer and magnetic layer to fill the third openings, the magnetic layer provides longitudinal biasing to the free layer.

7. The method of claim 6 wherein the magnetic layer in the third openings comprises a hard bias layer, or is a junction shield comprised of an antiferro-magnetically coupled configuration having a lower magnetic layer, a middle AFM coupling layer, and an upper magnetic layer.

8. The method of claim 1 wherein the second stack has a T shape from a top-down view wherein a vertical section extends from the front plane to height h 2 and has the first cross-track width, and wherein a horizontal section has a full cross-track width between the MR sensor far sides and behind the third stack backside.

9. The method of claim 1 wherein each of the third openings has a rectangular shape and extends from the front plane to a backside of the MR sensor.

10. The method of claim 1 wherein the outer side of each third opening extends to the first height from the front plane and each third opening has a diagonal side extending from the backside of the third stack to the first plane.

Assignees

• Headway Tech Inc

Inventors

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

Classifications

• 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

• G11B5/398

  Specially shaped layers · CPC title