# US 2014/0154529 A1 · Magnetoresistive sensor for a magnetic storage system read head, and fabrication method thereof

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- Number: US 2014/0154529 A1
- Document ID: US20140154529A1
- Status: Published application
- Kind: A1
- Application number: 13/691,695
- Filed: 2012-11-30
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Western Digital (Fremont), LLC
- Inventors: Cheng-Han YANG; Chen-Jung CHIEN; Christian KAISER; Yuankai ZHENG; Qunwen LENG; Mahendra PAKALA
- Web page: https://patentgrep.com/patent/US20140154529A1

## CPC

- G11B 5/3906: {Details related to the use of magnetic thin film layers or to their effects}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices}
- Y10T 29/49032: Fabricating head structure or component thereof
- Y10T 29/49034: Treating to affect magnetic properties
- Y10T 428/1114: having tunnel junction effect
- 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 read transducer including a magnetoresistive sensor is described, as well as a fabrication method thereof. The magnetoresistive sensor includes a cap layer overlaying a free layer. The cap layer is situated with a first thickness to absorb boron from the free layer. The magnetoresistive sensor is annealed, and boron is diffused from the free layer and absorbed by the cap layer, improving the magnetic performance of the free layer. The cap layer thickness is then reduced to a second thickness, thereby reducing the shield-to-shield (SS) stack spacing of the magnetoresistive sensor and allowing for increased areal recording density.

## Claims

### Claim 1

A method for providing a magnetic read transducer including a magnetoresistive sensor, wherein the magnetoresistive sensor includes a cap layer overlaying a free layer, the method comprising:
situating the cap layer with a first thickness to absorb boron from the free layer to the cap layer;
annealing the magnetoresistive sensor;
diffusing boron from the free layer and absorbing boron by the cap layer during the annealing the magnetoresistive sensor; and
reducing the cap layer thickness to a second thickness, after annealing the magnetoresistive sensor.

### Claim 2 (depends on 1)

The method as in claim 1, wherein the cap layer includes one of titanium, hafnium, zirconium, niobium, tantalum, and ruthenium.

### Claim 3 (depends on 1)

The method as in claim 1, wherein, during annealing, the cap layer forms titanium boride.

### Claim 4 (depends on 1)

The method as in claim 1, wherein, before annealing the magnetoresistive sensor, the free layer includes i.) CoFe, and ii.) at least one of CoB, CoB and Fe, and Co1-xFexBy, wherein x is one of 0 to 0.4, and 0 to 0.9, and y is 0.1 to 0.25.

### Claim 5 (depends on 1)

The method as in claim 1, wherein the first thickness is in a range of 40 angstroms to 200 angstroms, and the second thickness is in a range of 20 angstroms.

### Claim 6 (depends on 1)

The method as in claim 1, wherein reducing the cap layer thickness to the second thickness comprises reducing the cap layer thickness to less than 20 angstroms, and less than one-half of the first thickness.

### Claim 7 (depends on 1)

The method as in claim 1, further comprising overlaying the cap layer with a ruthenium layer, and overlaying the ruthenium layer with a tantalum layer, before annealing the magnetoresistive sensor.

### Claim 8 (depends on 1)

The method as in claim 1, further comprising overlaying the cap layer with a layer, after reducing the cap layer thickness to the second thickness.

### Claim 9 (depends on 8)

The method as in claim 8, wherein the layer overlaying the cap layer includes a nickel-iron layer overlaying the cap layer, and a ruthenium layer or a tantalum layer overlaying the nickel-iron layer.

### Claim 10 (depends on 1)

The method as in claim 1, wherein reducing the cap layer thickness comprises etching the cap layer via one of ion-beam milling, plasma etching, and chemical wet etching.

### Claim 11

A method for providing a magnetic read transducer including a magnetoresistive sensor, wherein the magnetoresistive sensor includes a cap layer overlaying a free layer, the method comprising:
forming an amorphous cap layer; and situating the amorphous cap layer to at least substantially inhibit the free layer from crystallizing in an orientation other than a body center cube crystal structure with a 100 plane (bcc (100)).

### Claim 12 (depends on 11)

The method as in claim 11, wherein the cap layer includes one of titanium, hafnium, zirconium, niobium, tantalum, and ruthenium.

### Claim 13 (depends on 11)

The method as in claim 11, wherein the cap layer includes titanium boride.

### Claim 14 (depends on 11)

The method as in claim 11, wherein the free layer includes i.) CoFe, and ii.) at least one of CoB, CoB and Fe, and Co1-xFexBy, wherein x is one of 0 to 0.4, and 0 to 0.9, and y is 0.1 to 0.25.

### Claim 15

A magnetic read transducer comprising a magnetoresistive sensor including a cap layer overlaying a free layer, wherein the cap layer is amorphous and situated to at least substantially inhibit the free layer from crystallizing in an orientation other than a body center cube crystal structure with a 100 plane (bcc (100)).

### Claim 16 (depends on 15)

The magnetic read transducer as in claim 15, wherein the cap layer includes one of titanium, hafnium, zirconium, niobium, tantalum, and ruthenium.

### Claim 17 (depends on 15)

The magnetic read transducer as in claim 15, wherein the cap layer includes titanium boride.

### Claim 18 (depends on 15)

The magnetic read transducer as in claim 15, wherein the cap layer thickness is less than 20 angstroms.

### Claim 19 (depends on 15)

The magnetic read transducer as in claim 15, wherein the free layer includes i.) CoFe, and ii.) at least one of CoB, CoB and Fe, and Co1-xFexBy, wherein x is one of 0 to 0.4, and 0 to 0.9, and y is 0.1 to 0.25.

### Claim 20 (depends on 15)

The magnetic read transducer as in claim 15, wherein the magnetoresistive sensor is a tunneling magnetoresistive (TMR) sensor or a giant magnetoresistive (GMR) sensor.