Reader designs of shield to shield spacing improvement

Patent metadata

Field	Value
Publication number	US-9437225-B2
Application number	US-201414445167-A
Country	US
Kind code	B2
Filing date	Jul 29, 2014
Priority date	Jul 29, 2014
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

A MR sensor is disclosed with an antiferromagnetic (AFM) layer recessed behind a first stack of layers including a free layer and non-magnetic spacer to reduce reader shield spacing and enable increased areal density. The AFM layer may be formed on a first pinned layer in the first stack that is partially embedded in a second pinned layer having a front portion at an air bearing surface (ABS) to improve pinning strength and avoid a morphology effect. In another embodiment, the AFM layer is embedded in a bottom shield and surrounds the sidewalls and back side of an overlying free layer in the sensor stack to reduce reader shield spacing. Pinning strength is improved because of increased contact between the AFM layer and a pinned layer. The free layer is aligned above a bottom shield center section.

First claim

We claim:

1. A read head including a magnetoresistive (MR) sensor, comprising:
(a) a bottom shield having a top surface;
(b) a first stack of layers including a seed layer contacting the bottom shield top surface, and a reference layer (RL), coupling layer, and PL2 pinned layer (PL2) in a seed layer/RL/coupling layer/PL2 configuration, the first stack has a first set of two sidewalls extending a first height from an air bearing surface (ABS), a first width in a cross-track direction, and a back side at the first height distance;
(c) second stack of layers including a non-magnetic spacer, free layer, and a first capping layer that are sequentially formed on a top surface of a PL2 front portion, the second stack has a track width in a cross-track direction, a second set of two sidewalls that extend a second height less than the first height from the ABS, and a back side connecting the second set of two sidewalls; and
(d) a third stack of layers comprising an antiferromagnetic (AFM) layer that pins a magnetization direction in the PL2 layer, the third stack is formed on a top surface of a PL2 back portion that is a certain distance below the top surface of the PL2 front portion, and the third stack has a front side facing the second stack back side wherein the third stack front side is at least a second height distance from the ABS and has a cross-track width greater than the track width, the third stack has a back side formed along a vertical plane in a down-track direction where the vertical plane includes the first stack back side.

2. The read head of claim 1 further comprising an isolation layer that forms a gap of up to 50 nm between the second stack back side and the third stack front side, the isolation layer also extends above a top surface of the third stack.

3. The read head of claim 2 wherein the third stack comprises a lower PL1 pinned layer (PL1), a middle AFM layer that is a Mn alloy, and an upper second capping layer in a PL1/AFM/capping layer configuration, the PL1 layer contacts the PL2 layer in the first stack between the third stack front side and the third stack back side.

4. The read head of claim 3 wherein a top surface of the PL2 back portion is formed a distance up to about 20 Angstroms below the top surface of the PL2 front portion.

5. The read head of claim 2 wherein the third stack comprises a lower AFM layer, and an upper second capping layer in an AFM/second capping layer configuration, the AFM layer contacts the PL2 layer in the first stack between the third stack front side and the third stack back side, and has a bottom surface that is formed below a top surface of the PL2 front portion.

6. The read head of claim 1 wherein the first width of the first stack is essentially equal to the track width.

7. The read head of claim 1 wherein the first width of the first stack is substantially greater than the track width.

8. The read head of claim 1 wherein the third stack has a trapezoidal shape from a down-track perspective such that the cross-sectional width of the third stack front side is less than a cross-sectional width of the third stack back side.

9. The read head of claim 1 wherein the third stack has a lower oxide AFM layer and an upper second capping layer, the front side of the third stack adjoins a back side of the second stack, and a bottom surface of the oxide AFM layer is formed a distance up to about 20 Angstroms below a top surface of the PL2 front portion.

10. The read head of claim 1 wherein the third stack comprises a lower PL1 pinned layer (PL1), a middle oxide AFM layer, and an upper second capping layer in a PL1/oxide AFM/capping layer configuration, the PL1 layer contacts the PL2 layer in the first stack between the third stack front side and the third stack back side.

11. The read head of claim 1 further comprising a top shield that contacts a top surface of the first capping layer in the first stack, and is formed on the third stack.

12. A read head including a magnetoresistive (MR) sensor with a top spin valve configuration, comprising:
(a) a bottom shield having a top surface;
(b) a first stack of layers including a seed layer contacting the bottom shield top surface, and a free layer (FL), non-magnetic spacer, and first pinned layer (PL1) in a seed layer/FL/non-magnetic spacer/PL1 configuration, the first stack has a first set of two sidewalls extending a first height from an air bearing surface (ABS), a track width in a cross-track direction, and a back side at the first height distance;
(c) a second stack of layers including a second pinned layer (PL2), coupling layer, reference layer (RL), and first capping layer that are sequentially formed on a top surface of the PL1 layer, the second stack has a first width in a cross-track direction, a second set of two sidewalls that extend a second height greater than the first height from the ABS, and a back side connecting the second set of two sidewalls; and
(d) a third stack of layers comprising an antiferromagnetic (AFM) layer that pins a magnetization direction in the PL2 layer, the third stack has a front side that is recessed at least a first height distance from the ABS and that faces the first stack back side, and the third stack has a back side formed along a vertical plane in a down-track direction where the vertical plane includes the second stack back side.

13. The read head of claim 12 further comprising an isolation layer that forms a gap between the first stack back side and the third stack front side, the isolation layer also separates the third stack from the bottom shield top surface.

14. The read head of claim 13 wherein the third stack comprises a lower second seed layer, and an upper AFM layer that is a Mn alloy, the AFM layer has a top surface that contacts a bottom surface of a back portion of the PL2 layer which is greater than a first height distance from the ABS, and is formed coplanar with a top surface of the PL1 layer.

15. The read head of claim 12 wherein the third stack comprises a lower second seed layer, and an upper oxide AFM layer, the second seed layer contacts the bottom shield top surface, and a top surface of the upper oxide AFM layer is formed coplanar with a top surface of the PL1 layer.

16. The read head of claim 15 wherein the third stack front side adjoins the first stack back side.

17. A read head including a magnetoresistive (MR) sensor, comprising:
(a) a bottom shield with a center section having a top surface, and two side sections formed on opposite sides of the bottom shield center section at an air bearing surface (ABS) and separated by a first width, the two side sections have a top surface formed a first distance in a down-track direction below the bottom shield center section top surface;
(b) a first stack of layers including a first seed layer contacting the top surface of each bottom shield side section, a middle antiferromagnetic (AFM) layer, and an upper first pinned layer (PL1), the first stack forms a continuous stripe around two sidewalls and back side of an overlying third stack and is comprised of two side portions that connect to a back portion, each side portion has a second width in a cross-track direction, an outer sidewall that connects to a first stack back side at a first height from the ABS, and and an inner sidewall that connects to a front side of the back portion at a second height from the ABS;
(c) a second stack of layers including a second pinned layer (PL2) that contacts a PL1 layer top surface, a coupling layer, and reference layer (RL), the second stack has two sidewalls that each share a vertical

Assignees

• Headway Tech Inc

Inventors

• Quan Junjie
• Zhang Kunliang
• Li Min
• Ding Ruhang
• Chye Yewhee
• Garfunkel Glen
• Chen Wenyu

Classifications

• G11B2005/3996

  large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices · CPC title

• G11B5/127

  Structure or manufacture of heads, e.g. inductive · 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

• G11B5/3909

  Arrangements using a magnetic tunnel junction · CPC title

• G11B5/3929

  Disposition of magnetic thin films not used for directly coupling magnetic flux from the track to the MR film or for shielding · CPC title