# US 8,570,690 B2 · Magnetic sensor having a hard bias seed structure

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- Number: US 8,570,690 B2
- Document ID: US8570690B2
- Status: Granted
- Kind: B2
- Application number: 13/164,610
- Filed: 2011-06-20
- Published: 2012-12-20
- Granted: 2013-10-29
- Earliest claimed: 2011-06-20
- Assignees: HGST Netherlands B.V.
- Applicants: Susumu Okamura; Hiroyuki Hoshiya; Takahiro Ibusuki
- Inventors: Susumu Okamura; Hiroyuki Hoshiya; Takahiro Ibusuki
- Web page: https://patentgrep.com/patent/US8570690B2

## CPC

- G11B 5/39: using magneto-resistive devices {or effects}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- G11B 5/3912: {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)}
- G11B 5/3932: {Magnetic biasing films}
- G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices}
- Y10T 428/1121: Multilayer
- 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 magnetic sensor having a novel hard bias structure that provides reduced gap spacing for increased data density. The magnetic sensor includes a sensor stack with first and second sides formed on a magnetic shield. A thin insulation layer is formed over the sides of the sensor stack and over the bottom shield. An under-layer comprising Cu—O is formed over the insulation layer and a hard magnetic bias layer is formed over the under-layer. The use of Cu—O as the under-layer allows the under-layer to be made thinner while still maintaining excellent magnetic properties in the hard bias layers formed there-over. This reduced thickness of the under-layer allows the gap spacing (spacing between the top and bottom magnetic shields) to be reduced, which in turn provides increased data density.

## Claims

### Claim 1

A magnetic sensor, comprising:
a sensor stack having first and second sides;
first and second under-layers each adjacent to a side of the sensor stack, each of the first and second under-layers comprising Cu—O; and
first and second hard magnetic bias layers each formed over one of the first and second under-layers;
wherein each of the first and second under-layers has a top surface that is close to a body centered cubic structure.

### Claim 2 (depends on 1)

The magnetic sensor as in claim 1 wherein each of the under-layers has a thickness of 30 Angstroms or less.

### Claim 3 (depends on 1)

The magnetic sensor as in claim 1 wherein each of the under-layers has a thickness of 10-20 Angstroms.

### Claim 4 (depends on 1)

The magnetic sensor as in claim 1 wherein each of the under-layers has a thickness of about 15 Angstroms.

### Claim 5 (depends on 1)

The magnetic sensor as in claim 1 further comprising non-magnetic capping layer formed over each of the first and second hard magnetic bias layers.

### Claim 6 (depends on 1)

The magnetic sensor as in claim 1 wherein each of the first and second hard magnetic bias layers comprises Co—Pt.

### Claim 7 (depends on 1)

The magnetic sensor as in claim 1 wherein each of the first and second hard magnetic bias layers comprises Co—Pt—Cr.

### Claim 8

A magnetic sensor, comprising:
a sensor stack having first and second sides;
first and second under-layers each adjacent to a side of the sensor stack, each of the first and second under-layers comprising Cu—O; and
first and second hard magnetic bias layers each formed over one of the first and second under-layers;
wherein the under-layer has a top surface with a within the plane axis ratio of 1.6.

### Claim 9 (depends on 8)

The magnetic sensor as in claim 8 wherein each of the under-layers has a thickness of 30 Angstroms or less.

### Claim 10 (depends on 8)

The magnetic sensor as in claim 8 wherein each of the under-layers has a thickness of 10-20 Angstroms.

### Claim 11 (depends on 8)

The magnetic sensor as in claim 8 wherein each of the under-layers has a thickness of about 15 Angstroms.

### Claim 12 (depends on 8)

The magnetic sensor as in claim 8 further comprising non-magnetic capping layer formed over each of the first and second hard magnetic bias layers.

### Claim 13 (depends on 8)

The magnetic sensor as in claim 8 wherein each of the first and second hard magnetic bias layers comprises Co—Pt.

### Claim 14 (depends on 8)

The magnetic sensor as in claim 8 wherein each of the first and second hard magnetic bias layers comprises Co—Pt—Cr.

### Claim 15

A magnetic sensor, comprising:
a bottom magnetic shield;
a sensor stack formed over the bottom magnetic shield and having first and second sides;
first and second insulation layers, each formed over a side of the sensor stack and over the bottom magnetic shield;
first and second under-layers each formed over at least a portion of one of the first and second insulation layers, each of the under-layers comprising Cu—O; and
first and second hard magnetic bias layers each formed over one of the first and second under-layers;
wherein each of the first and second under-layers has a top surface that is close to a body centered cubic structure.

### Claim 16

A magnetic sensor, comprising:
a bottom magnetic shield;
a sensor stack formed over the bottom magnetic shield and having first and second sides;
first and second insulation layers, each formed over a side of the sensor stack and over the bottom magnetic shield;
first and second under-layers each formed over at least a portion of one of the first and second insulation layers, each of the under-layers comprising Cu—O; and
first and second hard magnetic bias layers each formed over one of the first and second under-layers;
wherein the under-layer has a top surface with a within the plane axis ratio of 1.6.

### Claim 17

A magnetic disk drive, comprising:
a housing;
a magnetic media held within the housing;
an actuator pivotally mounted within the housing;
a slider connected with the actuator for movement adjacent to the magnetic media; and
a magnetic sensor formed on the slider, the magnetic sensor further comprising:
a sensor stack having first and second sides;
first and second under-layers each adjacent to a side of the sensor stack, each of the first and second under-layers comprising Cu—O; and
first and second hard magnetic bias layers each formed over one of the first and second under-layers;
wherein each of the first and second under-layers has a top surface that is close to a body centered cubic structure.

### Claim 18 (depends on 17)

The magnetic disk drive as in claim 17 wherein each of the under-layers has a thickness of 30 Angstroms or less.

### Claim 19 (depends on 17)

The magnetic disk drive as in claim 17 wherein each of the under-layers has a thickness of 10-20 Angstroms.

### Claim 20 (depends on 17)

The magnetic disk drive as in claim 17 wherein each of the under-layers has a thickness of about 15 Angstroms.