Dual free layer read head having recessed sidewall insulator layer and method of making thereof

Patent metadata

Field	Value
Publication number	US-12243565-B2
Application number	US-202318233800-A
Country	US
Kind code	B2
Filing date	Aug 14, 2023
Priority date	Jun 5, 2023
Publication date	Mar 4, 2025
Grant date	Mar 4, 2025

Abstract

A two-dimensional magnetic recording (TDMR) read head includes a lower reader and an upper reader. Each of the lower reader and the upper reader may have a dual free layer (DFL) magnetic tunnel junction structure having first and second free layers located between lower and upper shields. A synthetic antiferromagnetic (SAF) structure is located on a side of each magnetic tunnel junction. A sidewall insulating layer is located between the lower soft bias layer of the SAF structure and the first free layer. The sidewall insulating layer can have a reduced height such that an upper soft bias layer of the SAF structure is in direct contact with a sidewall of the second free layer, or the upper portion of the sidewall insulating layer located between the upper soft bias layer of the SAF structure and the sidewall of the second free layer has a reduced thickness.

First claim

What is claimed is:

1. A magnetic recording head comprising a first reader, wherein the first reader comprises:
a first lower shield;
a first dual free layer (DFL) sensor located over the first lower shield and comprising a first free layer, a second free layer and a first barrier layer located between the first free layer and the second free layer;
a first upper shield located over the first DFL sensor;
a first synthetic antiferromagnetic (SAF) structure located adjacent to a first side of the first DFL sensor, the first SAF structure comprising a first lower soft bias layer, a first upper soft bias layer, and a first spacer layer located between the first lower soft bias layer and the first upper soft bias layer; and
a first sidewall insulating layer comprising a first portion having a first thickness located between the first lower soft bias layer and the first free layer, wherein:
the first upper soft bias layer is in direct contact with a first sidewall of the second free layer; or
a second portion of the first sidewall insulating layer having a second thickness less than the first thickness is located between the first sidewall of the first upper soft bias layer and the second free layer.

2. The magnetic recording head of claim 1 , wherein the first reader further comprises a first rear hard bias structure located behind the first DFL sensor.

3. The magnetic recording head of claim 1 , wherein the first upper soft bias layer is in direct contact with the first sidewall of the second free layer.

4. The magnetic recording head of claim 3 , wherein the first spacer layer is in direct contact with the first sidewall of the second free layer.

5. The magnetic recording head of claim 4 , wherein the first spacer layer is in direct contact with a first sidewall of the first barrier layer.

6. The magnetic recording head of claim 3 , wherein:
the first lower soft bias layer is not in direct contact with and is laterally separated from the first free layer by the first portion of the first sidewall insulating layer; and
the first lower soft bias layer is not in direct contact with and is laterally separated from the first barrier layer by the first portion of the first sidewall insulating layer.

7. The magnetic recording head of claim 1 , wherein:
the first DFL sensor further comprises a capping layer located over the second free layer; and
the first upper soft bias layer is in direct contact with the capping layer.

8. The magnetic recording head of claim 1 , wherein the first reader further comprises:
a second synthetic antiferromagnetic (SAF) structure located adjacent to a second side of the first DFL sensor, the second SAF structure comprising a second lower soft bias layer, a second upper soft bias layer; and a second spacer layer located between the second lower soft bias layer and the second upper soft bias layer; and
a second sidewall insulating layer comprising a first portion having the first thickness located between the second lower soft bias layer and a second sidewall of the first free layer.

9. The magnetic recording head of claim 8 , wherein a second portion of the second sidewall insulating layer having the first thickness is located between the second upper soft bias layer and a second sidewall of the second free layer.

10. The magnetic recording head of claim 8 , wherein the second upper soft bias layer is in direct contact with a second sidewall of the second free layer.

11. The magnetic recording head of claim 8 , wherein a second portion of the second sidewall insulating layer having a second thickness less than the first thickness is located between the second upper soft bias layer and a second sidewall of the second free layer.

12. The magnetic recording head of claim 1 , wherein the second portion of the first sidewall insulating layer having the second thickness less than the first thickness is located between the first sidewall of the first upper soft bias layer and the second free layer.

13. The magnetic recording head of claim 1 , further comprising a second reader and an insulating reader separation gap located between the first reader and the second reader, wherein the magnetic recording head comprises a two-dimensional magnetic recording (TDMR) head.

14. The magnetic recording head of claim 13 , wherein the second reader comprises:
a second lower shield;
a second DFL sensor located over the second lower shield, the second DFL sensor being aligned with the first DFL sensor at an air bearing surface and comprising a third free layer, a fourth free layer, and a second barrier layer located between the third free layer and the fourth free layer;
a second upper shield layer located over the second DFL sensor;
a third synthetic antiferromagnetic (SAF) structure located adjacent to a first side of the second DFL sensor, the third SAF structure comprising a third lower soft bias layer, a third upper soft bias layer; and a third spacer layer located between the third lower soft bias layer and the third upper soft bias layer; and
a third sidewall insulating layer comprising a first portion having a first thickness located between the third lower soft bias layer and the third free layer.

15. The magnetic recording head of claim 14 , wherein the third upper soft bias layer is in direct contact with a first sidewall of the fourth free layer.

16. The magnetic recording head of claim 14 , wherein a second portion of the third sidewall insulating layer having a fourth second thickness less than the first thickness is located between the first sidewall of the third upper soft bias layer and the fourth free layer.

17. A magnetic recording device comprising the magnetic recording head of claim 1 .

Assignees

• Western Digital Tech Inc

Inventors

• Hu Chih-Ching
• Wang Yung-Hung
• Mao Ming
• Jiang Ming
• Okada Yukimasa
• De Albuquerque Goncalo Baiao

Classifications

• G11B5/3945

  Heads comprising more than one sensitive element · CPC title

• G11B5/398

  Specially shaped layers · CPC title

• G11B5/3912

  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 Primary

  Arrangements using a magnetic tunnel junction · CPC title