Plasmon generator self-annealing with current injection in TAMR

• US 8,848,495 B1
• Filed: 12/02/2013
• Issued: 09/30/2014
• Est. Priority Date: 12/02/2013
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Wu, Yan, Liu, Kowang
• Primary Examiner(s): Agustin, Peter Vincent
• Application Number:
  US14/093,993
• Time in Patent Office: 302 Days
• Field of Search: None
• US Class Current: 369/13.33
• CPC Class Codes: G02B 6/1226 involving surface plasmon interaction
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 5/3133 including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure G11B5/3106 takes precedence
• CPC Class Codes: G11B 5/314 where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers G11B5/3196 takes precedence
• CPC Class Codes: G11B 5/3163 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 Class Codes: G11B 5/6088 Optical waveguide in or on flying head

Abstract

A dual plasmon generator (PG) mirror image structure is used during fabrication of a TAMR head to locally anneal the PGs without substantially elevating the temperature in adjacent layers. Two PGs have narrow peg portions aligned head to head, and larger back end portions with a back side facing away from the eventual ABS. A first lead is attached to a back side of a first PG while a second lead is connected to a back side of a second PG. A 10 mA current is injected into a first PG and exits from the second PG and causes resistive heating in the rod-like portions where the temperature may be raised by 250° C. or more. A temporary overcoat layer may be formed over the PGs to dissipate heat and to keep the PGs from deforming during the annealing step.

Claims

1. A method for providing localized annealing to a plasmon generator of a thermally assisted magnetic recording (TAMR) head that is formed on a slider, comprising:

(a) providing an optical system with a stacked structure that comprises;

(1) a waveguide that is designed to capture light energy from a light source and propagate the light energy toward an end of the waveguide at an air bearing surface (ABS), the waveguide has a top surface aligned in a lengthwise direction that is perpendicular to the ABS and toward a back end of the TAMR head;

(2) a plasmon generator (PG) that has a bottom surface formed parallel to the waveguide top surface and separated therefrom by a first cladding layer;

light energy from the waveguide couples to a plasmon mode of the PG and is propagated as a surface plasmon (SP) mode to the ABS where the SP mode is focused on a magnetic medium to provide spot heating during a write process; and

(3) the first cladding layer formed between the waveguide and PG, the optical system is formed with a dual PG mirror image structure about a plane that approximates a final ABS position wherein an end of a first rod-like portion of a first PG adjoins an end of a second rod-like portion of a second PG along the plane, and back end portions of the first and second PG adjoin a second end of the first and second rod-like portions, respectively, at a first distance from the plane;

(b) attaching a first lead to a back end portion of the first PG to form a positive terminal, and attaching a second lead to a back end portion of the second PG to form a negative terminal;

(c) depositing an overcoat layer made of an insulation material on the slider; and

(d) injecting a first current through the first lead that passes through the dual PG mirror image structure and exits through the second lead thereby causing resistive heating to locally anneal the rod-like portions of the first PG and second PG without substantially elevating a temperature in the back end portions or in adjacent regions of the optical system or TAMR head.

2. The method of claim 1 further comprised of injecting a second current through the first lead that passes through the dual PG mirror image structure and exits by way of the second lead, the second current is used to probe the dual PG mirror image structure to determine the extent of annealing achieved by the first current injection.

3. The method of claim 2 further comprised of selectively removing the overcoat layer with a reactive ion etch that does not significantly erode the first cladding layer.

4. The method of claim 3 further comprised of depositing a second cladding layer along sidewalls of the back end portions and to completely cover the rod-like portions, and then forming a write pole layer that contacts a top surface of the back end portions.

5. The method of claim 1 wherein the plasmon generator is made of Au, Ag, Cu, or AuCo.

6. The method of claim 3 wherein the first and second cladding layers are comprised of alumina, and the overcoat layer is made of silicon oxide or TaOx.

7. The method of claim 6 wherein the reactive ion etch comprises CF₄.

8. The method of claim 1 wherein the first current is a DC current or pulsed current with an amplitude of about 10 to 100 mA.

9. The method of claim 2 wherein the second current has an amplitude in the range of about 0.5 to 1 mA.

10. The method of claim 1 wherein the back end portions of the plasmon generators have a greater cross-sectional width and a greater down-track thickness than the first and second rod-like portions such that a first volume of a back end portion is substantially larger than a second volume of a rod-like portion.

11. The method of claim 1 wherein each of the back end portions has a parabolic shape formed proximate to the second end of a rod-like portion wherein opposing sides of the parabola shape have a greater separation in a cross-track direction with increasing distance from the second end as observed from a top-down view along a down-track direction.

12. The method of claim 8 wherein the first current raises a temperature in the rod-like portions of the dual PG mirror image structure by up to 250°

C. or more such that the temperature achieved during the annealing step exceeds operational temperatures in the TAMR head after TAMR head fabrication is completed in subsequent steps.

13. A thermally assisted magnetic recording (TAMR) head structure that enables a plasmon generator component therein to be selectively annealed without substantially elevating a temperature in adjacent layers in the TAMR head, comprising:

(a) an optical system with a stacked structure that is formed on a substrate and comprises;

(1) a waveguide that is designed to capture light energy from a light source and propagate the light energy toward an end of the waveguide at an air bearing surface (ABS), the waveguide has a top surface aligned in a lengthwise direction that is perpendicular to the ABS and toward a back end of the TAMR head;

(2) a plasmon generator (PG) that has a bottom surface formed parallel to the waveguide top surface and separated therefrom by a first cladding layer;

light energy from the waveguide couples to a plasmon mode of the PG and is propagated as a surface plasmon (SP) mode to the ABS where the SP mode is focused on a magnetic medium to provide spot heating to facilitate a write process; and

(3) the first cladding layer formed between the waveguide and PG, the optical system is formed with a dual PG mirror image structure about a plane that approximates a final ABS position wherein an end of a first rod-like portion of a first PG adjoins an end of a second rod-like portion of a second PG along the plane, and back end portions of the first and second PG adjoin a second end of the first and second rod-like portions, respectively, at a first distance from the plane;

(b) a first lead from a power source that is connected to a back end portion of the first PG to form a positive terminal, and a second lead from the power source that is attached to a back end portion of the second PG to form a negative terminal to complete a circuit that allows a current to pass through the dual PG mirror image structure and thereby anneals the rod-like portions as a result of resistive heating; and

(c) an overcoat layer made of an insulation material that is formed on the first cladding layer and covers the dual PG mirror image structure.

14. The TAMR head structure of claim 13 wherein the substrate is a return pole, and a bottom surface of the waveguide contacts a top surface of the return pole.

15. The TAMR head structure of claim 13 wherein the first and second plasmon generators are made of Au, Ag, Cu, or AuCo.

16. The TAMR head structure of claim 13 wherein the first and second rod-like portions have a rectangular or square shape from a cross-sectional view along the plane.

17. The TAMR head structure of claim 13 wherein the first cladding layer is comprised of alumina, and the overcoat layer is made of silicon oxide or TaOx.

18. The TAMR head structure of claim 13 wherein the current is a DC current or pulsed current with an amplitude of about 10 to 100 mA.

19. The TAMR head structure of claim 13 wherein the back end portions of the plasmon generators have a greater cross-sectional width and a greater down-track thickness than the first and second rod-like portions such that a first volume of a back end portion is substantially larger than a second volume of a rod-like portion.

20. The TAMR head structure of claim 13 wherein each of the back end portions has a parabolic shape formed proximate to the second end of a rod-like portion wherein opposing sides of the parabola shape have a greater separation in a cross-track direction with increasing distance from the second end as observed from a top-down view along a down-track direction.

21. The TAMR head structure of claim 13 wherein each rod-like portion extends a distance of about 5 to 150 nm from the plane.

22. A method of fabricating a thermally assisted magnetic recording (TAMR) write head with a leading magnetics design, comprising:

(a) providing a return pole on a substrate wherein the return pole has a pedestal structure having a top surface;

(b) forming a waveguide layer that has a bottom surface contacting the top surface of the pedestal, and a top surface that extends in a lengthwise direction that is perpendicular to a first plane that is proximate to an eventual air bearing surface (ABS) position;

(c) depositing a first cladding layer on the waveguide layer;

(d) forming a dual plasmon generator (PG) mirror image structure on the first cladding layer wherein each PG has a rod-like portion with a first end that adjoins the first plane, and a back end adjoining a second end of the rod-like portion along a second plane formed parallel to the first plane;

(e) annealing the rod-like portions of the dual PG mirror image structure by injecting a current that passes from a back side of a first PG to a back side of a second PG through a circuit that comprises two leads and a power source;

(f) forming a second cladding layer on the first cladding layer and along sidewalls of the dual PG mirror image structure, the second cladding layer has a top surface that is coplanar with a top surface of the first PG and of the second PG;

(g) forming a write pole on the dual PG mirror image structure such that a bottom or leading surface of the write pole contacts the top surface of the first PG and the top surface of the second PG; and

(h) slicing the substrate along the first plane to form a first TAMR head comprising a first PG, and a second TAMR head comprising a second PG.

23. The method of claim 22 wherein the substrate is a read head in a combined read head/write head structure.

24. The method of claim 22 wherein the first and second plasmon generators are made of Au, Ag, Cu, or AuCo.

25. The method of claim 22 wherein the first and second rod-like portions have a rectangular or square shape from a cross-sectional view along the first plane.

26. The method of claim 22 wherein the current is a DC current or pulsed current with an amplitude of about 10 to 100 mA.

27. The method of claim 22 wherein the back end portions of the plasmon generators have a greater cross-sectional width and a greater down-track thickness than the first and second rod-like portions such that a first volume of a back end portion is substantially larger than a second volume of a rod-like portion.

28. The method of claim 22 wherein each of the back end portions has a parabolic shape formed proximate to the second end of a rod-like portion wherein opposing sides of the parabola shape have a greater separation in a cross-track direction with increasing distance from the second end as observed from a top-down view along a down-track direction.

29. The method of claim 22 wherein the rod-like portions and back end portions of the dual PG mirror image structure each have a bottom surface that is formed along a third plane which faces a top waveguide surface.

30. The method of claim 22 wherein the current raises a temperature in the rod-like portions of the dual PG mirror image structure to a temperature that exceeds an operational temperature in the first and second TAMRs.