# US 10,482,907 B1 · Methods of protecting write pole from corrosion in HAMR head

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- Number: US 10,482,907 B1
- Document ID: US10482907B1
- Status: Granted
- Kind: B1
- Application number: 16/144,936
- Filed: 2018-09-27
- Granted: 2019-11-19
- Earliest claimed: 2018-09-27
- Assignees: Western Digital Technologies, Inc.
- Applicants: Western Digital Technologies, Inc.
- Inventors: Mousumi Mani Biswas; Marc A Finot; Barry Cushing Stipe
- Web page: https://patentgrep.com/patent/US10482907B1

## CPC

- G11B 5/40: Protective measures on heads, e.g. against excessive temperature (G11B5/31 takes precedence; protection against wear G11B5/255 {; protective structure of the head: see under structures, e.g. G11B5/3106})
- G11B 5/6082: {Design of the air bearing surface}
- G11B 2005/0021: {Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal}
- 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)

## Abstract

A write pole in a heat assisted magnetic recording (HAMR) head for writing to a HAMR medium is provided that includes a recessed part proximal to a near field transducer (NFT) in the HAMR head to protect the write pole from corrosion. The recessed part extends from a portion of a bottom surface of the write pole along a portion of a side of the write pole proximal to the NFT. Within the recessed part, a pole pedestal may be formed of a material that is resistant to corrosion. The pole pedestal may have a rectangular, chamfered, or L-shape. The recessed part may further be induced on the portion of bottom surface of the write pole that extends along the portion of the side of the write pole.

## Claims

### Claim 1

A heat assisted magnetic recording (HAMR) head for writing to a HAMR medium, comprising:
a near field transducer (NFT) comprising an end proximal to an air bearing surface (ABS) and configured to direct light from a laser to a region on the HAMR medium; and
a write pole configured to write to the region on the HAMR medium and comprising a bottom surface proximal to the ABS, a first side proximal to the NFT and a second side opposite the first side;
wherein the write pole comprises a recessed part extending from a portion of the bottom surface along a portion of the first side;
wherein the portion of the bottom surface has a length less than a total length of the bottom surface and the portion of the first side has a height less than a total length of the first side;
wherein the recessed part is embedded in the write pole.

### Claim 2 (depends on 1)

The HAMR head of claim 1, further comprising:
a pole pedestal within the recessed part.

### Claim 3 (depends on 2)

The HAMR head of claim 2, wherein the pole pedestal comprises a material selected from the group consisting of a noble metal or alloy of Rh, Ru, Jr, Ni, V, Au, Pt, Ti, Cr, or Ta.

### Claim 4 (depends on 2)

The HAMR head of claim 2, wherein the pole pedestal comprises a material selected from the group consisting of Ta2O3, Y2O3, Cr2O3, ZrO2, HfO2, TiO2, SiO2, Ferrite, Ba-Ferrite, Zn-Ferrite, or Sr-Ferrite.

### Claim 5 (depends on 2)

The HAMR head of claim 2, wherein the pole pedestal comprises a material selected from the group consisting of Si, Ta, Zr, Ti, Hf, or Y.

### Claim 6 (depends on 2)

The HAMR head of claim 2, wherein the pole pedestal comprises a magnetic material comprising a lower magnetic moment than the write pole or a higher atomic percentage of nickel than the write pole.

### Claim 7 (depends on 2)

The HAMR head of claim 2, wherein a cross section of the pole pedestal comprises a rectangular shape that comprises a length extending along the bottom surface and a width extending along the first side, wherein the length is greater than the width.

### Claim 8 (depends on 2)

The HAMR head of claim 2, wherein:
the pole pedestal comprises a first segment extending along the bottom surface of the write pole and a second segment extending from the bottom surface along the first side of the write pole; and
the first segment and the second segment form an L-shape block.

### Claim 9 (depends on 2)

The HAMR head of claim 2, wherein the pole pedestal comprises a chamfer shape such that a relative distance between the NFT and the write pole decreases from the ABS along the first side.

### Claim 10 (depends on 1)

The HAMR head of claim 1, wherein:
the recessed part is induced on the bottom surface of the write pole; and
the recessed part comprises a chamfer shape such that a relative distance between the NFT and the write pole decreases from the ABS along the first side.

### Claim 11 (depends on 10)

The HAMR head of claim 10, further comprising:
a protective layer on a chamfered edge of the write pole adjacent the recessed part, wherein the protective layer further extends along at least an additional portion of the bottom surface, wherein the protective layer comprises a material selected from the group consisting of a noble metal or alloy of Rh, Ru, IR, Au, or Pt.

### Claim 12 (depends on 1)

The HAMR head of claim 1, further comprising:
a heat sink thermally coupled to the recessed part.

### Claim 13 (depends on 1)

A data storage device comprising the HAMR head of claim 1.

### Claim 14

A method for fabricating a heat assisted magnetic recording (HAMR) head for writing to a HAMR medium, the method comprising:
providing a waveguide optically coupled to a laser and configured to direct light from the laser towards an air bearing surface (ABS) of the HAMR head;
providing a near field transducer (NFT) comprising an end proximal to the ABS and optically coupled to the waveguide to focus the light onto a region on the HAMR magnetic recording medium; and
providing a write pole configured to write to the region on the HAMR magnetic recording medium and comprising a bottom surface proximal to the ABS, a first side proximal to the NFT and a second side opposite the first side, wherein providing the write pole further comprises:
forming a recessed part extending from a portion of the bottom surface along a portion of the first side, wherein the portion of the bottom surface has a length less than a total length of the bottom surface and the portion of the first side has a height less than a total length of the first side, wherein the recessed part is embedded in the write pole.

### Claim 15 (depends on 14)

The method of claim 14, wherein providing the write pole further comprises:
filling the recessed part with a material forming a pole pedestal.

### Claim 16 (depends on 15)

The method of claim 15, wherein filling the recessed part with the material forming the pole pedestal further comprises:
forming a first segment of the pole pedestal extending along the bottom surface of the write pole; and
forming a second segment of the pole pedestal extending from the bottom surface along the first side of the write pole, wherein the first segment and the second segment form an L-shape block.

### Claim 17 (depends on 15)

The method of claim 15, wherein filling the recessed part with the material forming the pole pedestal further comprises:
forming the pole pedestal comprising a chamfer shape such that a relative distance between the NFT and the write pole decreases from the ABS along the first side.

### Claim 18 (depends on 14)

The method of claim 14, wherein forming the recessed part further comprises:
inducing the recessed part comprising a chamfer shape along the portion of the bottom surface and the portion of the first side such that a relative distance between the NFT and the write pole decreases from the ABS along the first side.

### Claim 19 (depends on 14)

The method of claim 14, further comprising:
providing a heat sink thermally coupled to the recessed part; and
providing at least one coil configured to generate a magnetic field transferred to the write pole to apply a recording magnetic field to the region on the HAMR medium.

### Claim 20

A heat assisted magnetic recording (HAMR) head for writing to a HAMR medium, comprising:
means for directing light from a laser to a region on the HAMR medium through an air bearing surface (ABS) of the HAMR head; and
means for writing to the region on the HAMR medium comprising a bottom surface proximal to the ABS and a side proximal to the means for directing light, wherein the means for writing further comprises means for protecting the means for writing from corrosion;
wherein the means for protecting extends from a portion of the bottom surface along a portion of the side;
wherein the portion of the bottom surface has a length less than a total length of the bottom surface and the portion of the side has a height less than a total length of the side;
wherein the means for protecting is embedded in the means for writing.