Magnetic pole self-annealing with current injection in perpendicular magnetic recording (PMR)

Patent metadata

Field	Value
Publication number	US-9218830-B2
Application number	US-201414190415-A
Country	US
Kind code	B2
Filing date	Feb 26, 2014
Priority date	Feb 26, 2014
Publication date	Dec 22, 2015
Grant date	Dec 22, 2015

Abstract

A main pole structure is selectively annealed by attaching a lead to a back side thereof and electrically connecting a lead to a front end of a narrow pole tip portion such that when a first current passes between the leads there is resistive heating that raises the temperature in the narrow pole tip to 250° C. to 400° C. As a result, defects and stress level are reduced in the narrow pole tip portion without substantially increasing a temperature in adjacent regions including the read head. Annealing may be performed with a partially completed main pole structure or with a completely fabricated write head. Leads may be removed or left in place after annealing is finished. The extent of annealing may be determined by calculating a difference between resistance measurements taken before and after annealing.

First claim

We claim:

1. A method for locally annealing a main pole structure in a write head, comprising:
(a) providing a main pole structure on a substrate wherein the main pole structure comprises a narrow pole tip portion with a front end that adjoins a plane formed proximate to an eventual air bearing surface (ABS) plane, and a yoke portion that adjoins the pole tip portion along a back end at a plane that is a neck height distance from the eventual ABS plane;
(b) attaching a first lead to a back side of the yoke portion to form a first terminal, and electrically connecting a second lead to the front end of the narrow pole tip portion to form a second terminal; and
(c) injecting a first current through the first lead that passes through the main pole structure including the narrow pole tip portion and exits through the second lead thereby causing resistive heating to locally anneal the narrow pole tip portion without substantially elevating a temperature in adjacent layers of the write head.

2. The method of claim 1 further comprised of:
(d) injecting a second current through the first lead that passes through the main pole structure and exits by way of the second lead to obtain a first resistance measurement before the first current is injected;
(e) injecting a third current between the first and second leads and through the main pole structure after the first current is injected to obtain a second resistance measurement; and
(f) determining the effect of annealing in the narrow pole tip portion by calculating a difference between the first and second resistance measurements.

3. The method of claim 2 wherein the second and third currents have an amplitude in the range of about 0.5 to 1 mA.

4. The method of claim 2 wherein a sequence of the second current injection followed by the first current injection, and then the third current injection is performed more than once.

5. The method of claim 1 further comprised of forming an overcoat layer made of an insulation material on the main pole structure, the overcoat layer serves to prevent oxidation of the main pole structure and dissipates heat during the first current injection.

6. The method of claim 1 wherein the first current is a DC current, AC current, or pulsed current with an amplitude of about 5 mA to 100 mA.

7. The method of claim 6 wherein a temperature of about 250° C. to 400° C. is generated in the narrow pole tip portion.

8. The method of claim 1 wherein local annealing is performed after the main pole structure is completely formed but before any additional write head layers are formed on the main pole structure.

9. The method of claim 1 wherein first current injection is performed after the write head is completely fabricated.

10. The method of claim 1 wherein local annealing is performed before the main pole structure is completely formed.

11. A method for locally annealing a main pole structure in a perpendicular magnetic recording (PMR) head that is formed on a substrate, comprising:
(a) providing a dual main pole structure in a mirror image configuration wherein each main pole structure is formed with a first insulation layer on the substrate, and each main pole structure comprises a narrow pole tip portion with a front end that adjoins a plane formed proximate to an eventual air bearing surface (ABS) plane, the narrow pole tip portion has a back end along a plane that is a neck height distance from the front end and adjoins a yoke portion;
(b) attaching a first lead to a back side of the yoke portion in a first main pole structure to form a positive terminal, and attaching a second lead to a back side of a yoke portion in a second main pole structure to form a negative terminal; and
(c) injecting a first current through the first lead that passes through the dual main pole structure including the narrow pole tip portions before exiting the second lead thereby causing resistive heating to locally anneal the narrow pole tip portions of the first and second main pole structures without substantially elevating a temperature in adjacent regions of the PMR head.

12. The method of claim 11 further comprised of:
(d) injecting a second current through the first lead that passes through the dual main pole structure and exits by way of the second lead to obtain a first resistance measurement before the first current is injected;
(e) injecting a third current between the first and second leads and through the dual main pole structure after the first current is injected to obtain a second resistance measurement; and
(f) determining the effect of localized annealing in the narrow pole tip portions by calculating a difference between the first and second resistance measurements.

13. The method of claim 12 wherein the second and third currents have an amplitude in the range of about 0.5 to 1 mA.

14. The method of claim 12 wherein a sequence of the second current injection followed by the first current injection, and then the third current injection is performed more than once.

15. The method of claim 11 further comprised of forming an overcoat layer made of an insulation material on the dual main pole structure before injecting the first current.

16. The method of claim 11 wherein the first current is a DC current, AC current, or pulsed current with an amplitude of about 5 mA to 100 mA.

17. The method of claim 16 wherein a temperature of about 250° C. to 400° C. is generated in the narrow pole tip portions of the main pole structures.

18. The method of claim 11 wherein the local annealing is performed after the main pole structures are completely formed but before any additional PMR head layers are formed on the dual main pole structure.

19. The method of claim 11 wherein injecting the first current is performed after the PMR head is completely fabricated.

20. The method of claim 11 wherein the local annealing is performed before the PMR head is completely formed.

Assignees

• Headway Technologies Inc

Inventors

• Wu Yan
• Liu Kowang

Classifications

• G11B5/1278

  specially adapted for magnetisations perpendicular to the surface of the record carrier · CPC title

• G11B5/3163 Primary

  Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers · CPC title

• G11B5/6082

  Design of the air bearing surface · CPC title

• G11B5/3116

  Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks (G11B5/3113, G11B5/245 take precedence) · CPC title

• Y10T29/49032

  Fabricating head structure or component thereof · CPC title