# US 2008/0186626 A1 · Method of fabricating a magnetic head having a CPP sensor with ELG fabrication and a partially milled stripe height

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- Number: US 2008/0186626 A1
- Document ID: US20080186626A1
- Status: Published application
- Kind: A1
- Application number: 11/703,383
- Filed: 2007-02-06
- Published: 2008-08-07
- Earliest claimed: 2007-02-06
- Assignees: HGST Netherlands B.V.
- Inventors: Ying Hong; David John Seagle
- Web page: https://patentgrep.com/patent/US20080186626A1

## CPC

- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
- G11B 5/3166: {Testing or indicating in relation thereto, e.g. before the fabrication is completed}
- G11B 5/3903: {using magnetic thin film layers or their effects, the films being part of integrated structures}
- G11B 5/3169: {Working or finishing the interfacing surface of heads, e.g. lapping of heads}
- Y10T 29/49021: Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method of fabricating a magnetic head including a CPP read head sensor. The CPP sensor includes a layered sensor stack including a free magnetic layer, a tunnel barrier layer, a pinned magnetic layer and an antiferromagnetic layer. An ion milling process is used to perform a partial depth material removal to establish the back wall of the sensor stack, where the antiferromagnetic layer is not milled through to create the back wall of the sensor stack. ELGs are fabricated during said ion milling process, and in an embodiment the ELGs are disposed at a same level as the tunnel barrier layer and are coplanar therewith.

## Claims

### Claim 1

A method for fabricating a magnetic head on a wafer substrate, comprising:
fabricating a CPP read sensor including:
depositing a plurality of sensor layers upon a base layer, said sensor layers including an antiferromagnetic layer, a pinned magnetic layer, a tunnel barrier layer and a free magnetic layer;
removing portions of said sensor layers;
depositing ELG material in locations where said sensor layers are removed;
fabricating a milling mask upon remaining portions of said sensor layers and upon said ELG material, said milling mask having a back edge portion that is disposed to form a back edge of some of said sensor layers, and said milling mask also having another back edge portion that is disposed to form a back edge of said ELG material; and
milling unmasked portions of some of said sensor layers to create a back edge of some of said sensor layers, wherein said antiferromagnetic layer is not milled; and milling unmasked portions of said ELG material to create a back edge of said ELG material.

### Claim 2 (depends on 1)

A method for fabricating a magnetic head as described in claim 1, wherein said tunnel barrier layer is milled in said milling step to create a back edge thereof.

### Claim 3 (depends on 1)

A method for fabricating a magnetic head as described in claim 1, wherein said pinned magnetic layer is not milled in said milling step.

### Claim 4 (depends on 1)

A method for fabricating a magnetic head as described in claim 1, wherein said tunnel barrier layer is comprised of a material selected from the group consisting of MgOx, TiOx and AlOx.

### Claim 5 (depends on 1)

A method for fabricating a magnetic head as described in claim 1, wherein said tunnel barrier layer is comprised of MgOx.

### Claim 6 (depends on 4)

A method for fabricating a magnetic head as described in claim 4, wherein said ELG material is comprised of Ta/Rh.

### Claim 7 (depends on 6)

A method for fabricating a magnetic head as described in claim 6, wherein said Rh portion of the ELG material is fabricated with a thickness of from approximately 50 Å to approximately 150 Å.

### Claim 8 (depends on 1)

A method for fabricating a magnetic head as described in claim 1, wherein said ELG material is disposed at a wafer level that is coplanar with said tunnel barrier layer.

### Claim 9

A method for fabricating a magnetic head upon a wafer substrate, comprising:
fabricating a CPP read sensor including:
depositing a plurality of sensor layers upon a base layer, said sensor layers including an antiferromagnetic layer, a pinned magnetic layer, a tunnel barrier layer and a free magnetic layer upon a base layer;
fabricating a first milling mask upon said sensor layers, said first milling mask being formed to cover a central portion of said sensor layers while not covering field portions of said sensor layers;
first milling unmasked portions of said sensor layers;
depositing a layer of ELG material;
removing said first milling mask;
fabricating a second milling mask upon said central portion of said sensor layers and upon an ELG portion of said ELG layer;
second milling unmasked portions of said sensor layers and said ELG layer;
depositing a first fill layer to a depth of approximately equal to a depth of said sensor layers;
removing said second milling mask;
fabricating a third milling mask upon portions of said central portion of said sensor layers and said ELG material, said third milling mask having a back edge portion that is disposed to form a back edge of some of said sensor layers, and said third milling mask also having another back edge portion that is disposed to form a back edge of said ELG material;
third milling unmasked portions of said sensor layers to create a back edge of some of said sensor layers, wherein said antiferromagnetic layer is not milled in this third milling, and milling unmasked portions of said ELG material to create a back edge of said ELG material.

### Claim 10 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said tunnel barrier layer is milled in said milling step to create a back edge thereof.

### Claim 11 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said pinned magnetic layer is not milled in said milling step.

### Claim 12 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said tunnel barrier layer is comprised of alumina.

### Claim 13 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said tunnel barrier layer is comprised of a material selected from the group consisting of MgOx, TiOx and AlOx.

### Claim 14 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said tunnel barrier layer is comprised of MgOx.

### Claim 15 (depends on 13)

A method for fabricating a magnetic head as described in claim 13, wherein said ELG material is comprised of Ta/Rh.

### Claim 16 (depends on 15)

A method for fabricating a magnetic head as described in claim 15, wherein said Rh ELG material is fabricated with a thickness of from approximately 50 Å to approximately 150 Å.

### Claim 17 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein said ELG material is disposed at a wafer level that is coplanar with said tunnel barrier layer.

### Claim 18 (depends on 9)

A method for fabricating a magnetic head as described in claim 9, wherein a fill layer is deposited to a depth of approximately said AFM layer prior to said deposition of said layer of ELG material.

### Claim 19

A method for fabricating a magnetic head upon a wafer substrate, comprising:
fabricating a CPP read sensor including:
depositing a plurality of sensor layers upon a base layer including an antiferromagnetic layer, a pinned magnetic layer, a tunnel barrier layer and a free magnetic layer upon a base layer;
fabricating a first milling mask upon said sensor layers, said first milling mask being formed to cover a central portion of said sensor layers while not covering field portions of said sensor layers;
first milling unmasked portions of said sensor layers;
depositing a fill layer to a depth of approximately said AFM layer;
depositing a layer of ELG material;
removing said first milling mask;
fabricating a second milling mask upon said central portion of said sensor layers and upon an ELG portion of said ELG layer;
second milling unmasked portions of said sensor layers and said ELG layer;
depositing another fill layer to a depth of approximately equal to a depth of said sensor layers;
removing said second milling mask;
fabricating a third milling mask upon portions of said central portion of said sensor layers and said ELG material, said third milling mask having a back edge portion that is disposed to form a back edge of some of said sensor layers, and said third milling mask also having another back edge portion that is disposed to form a back edge of said ELG material;
third milling unmasked portions of said sensor layers to create a back edge of some of said sensor layers, wherein said antiferromagnetic layer is not milled in this third milling, and milling unmasked portions of said ELG material to create a back edge of said ELG material.

### Claim 20 (depends on 19)

A method for fabricating a magnetic head as described in claim 19, wherein said tunnel barrier layer is milled in said milling step to create a back edge thereof.

### Claim 21 (depends on 19)

A method for fabricating a magnetic head as described in claim 19, wherein said pinned magnetic layer is not milled in said milling step.

### Claim 22 (depends on 19)

A method for fabricating a magnetic head as described in claim 19, wherein said tunnel barrier layer is comprised of a material selected from the group consisting of MgOx, TiOx and AlOx.

### Claim 23 (depends on 19)

A method for fabricating a magnetic head as described in claim 19, wherein said tunnel barrier layer is comprised of MgOx.

### Claim 24 (depends on 22)

A method for fabricating a magnetic head as described in claim 22, wherein said ELG material is comprised of Ta/Rh.

### Claim 25 (depends on 24)

A method for fabricating a magnetic head as described in claim 24, wherein said Rh ELG material is fabricated with a thickness of from approximately 50 Å to approximately 150 Å.

### Claim 26 (depends on 19)

A method for fabricating a magnetic head as described in claim 19, wherein said ELG material is disposed at a wafer level that is coplanar with said tunnel barrier layer.

### Claim 27

A magnetic head, comprising:
a CPP read sensor including a tunnel barrier layer;
at least one portion of ELG material that is coplanar with said tunnel barrier layer.

### Claim 28 (depends on 27)

A magnetic head as described in claim 27, wherein said ELG material is comprised of Ta/Rh.

### Claim 29 (depends on 28)

A magnetic head as described in claim 28, wherein said Rh ELG material is fabricated with a thickness of from approximately 50 Å to approximately 150 Å.

### Claim 30 (depends on 28)

A magnetic head as described in claim 28, wherein said tunnel barrier layer is comprised of a material selected from the group consisting of MgOx, TiOx and AlOx.

### Claim 31 (depends on 28)

A magnetic head as described in claim 28, wherein said tunnel barrier layer is comprised of MgOx.

### Claim 32

A hard disk drive including a magnetic head, comprising:
a magnetic head including a CPP read sensor including a tunnel barrier layer;
at least one portion of ELG material that is coplanar with said tunnel barrier layer.

### Claim 33 (depends on 32)

A hard disk drive as described in claim 32, wherein said ELG material is comprised of Ta/Rh.

### Claim 34 (depends on 33)

A hard disk drive as described in claim 33, wherein said Rh ELG material is fabricated with a thickness of from approximately 50 Å to approximately 150 Å.

### Claim 35 (depends on 33)

A hard disk drive as described in claim 33, wherein said tunnel barrier layer is comprised of a material selected from the group consisting of MgOx, TiOx and AlOx.

### Claim 36 (depends on 33)

A hard disk drive as described in claim 33, wherein said tunnel barrier layer is comprised of MgOx.