Parabolic-shaped plasmonic waveguide blocker for thermally assisted recording head

Abstract

To improve a thermal gradient of a near-field transducer (NFT) and increase an areal density capacity of a HAMR head.SOLUTION: An NFT includes a main pole (MP) 302, a two-layer transducer 304 positioned adjacent to the MP, a waveguide core 306, and a parabolic waveguide blocker 308 positioned adjacent to the waveguide core, wherein the parabolic waveguide blocker includes a parabolic shape having a surface exposed to an air-bearing surface (ABS) of a write head. The parabolic waveguide blocker reduces electromagnetic radiation from the waveguide core, recycles a scattering field emitted from the NFT to mitigate a thermal background in a recording medium, improves a thermal gradient, and increases an areal density capacity (ADC) of a hard disk drive write head.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 18 / 678,681, filed May 30, 2024, which is incorporated herein by reference in its entirety.

[0002] (Technical field) FIELD OF THE INVENTION Embodiments of the present invention relate to the field of electromechanical data storage devices, and more particularly to a waveguide blocker for a near-field transducer having a parabolic shape. [Background technology]

[0003] Magnetic recording media (e.g., magnetic disks) can store magnetic bits that represent digital data. A magnetoresistive writer can form part of a hard disk drive (HDD) that writes digital data to the magnetic recording media.

[0004] As the total amount of digital data stored on HDD devices increases, there is a growing demand for increased data capacity for HDD devices. One technology for increasing the data capacity of HDDs is heat-assisted magnetic recording (HAMR) or microwave-assisted magnetic recording (MAMR). HAMR and MAMR technologies can increase the density of HDDs by manipulating portions of the magnetic recording medium and improve the writing performance of the write head on the magnetic recording medium. Summary of the Invention [Problem to be solved by the invention]

[0005] In a HAMR recording head, near-field surface plasmon resonance on the NFT can be excited by the waveguide, heating the recording medium. Although most of the optical energy is coupled into the NFT, there may be some uncoupled optical energy that ultimately radiates into the recording medium as background. This uncoupled light can reduce the confinement of the heat spot and further cause a reduction in the thermal gradient. [Means for solving the problem]

[0006] The present embodiment relates to a near-field transducer (NFT) for a hard disk drive write head having a parabolic waveguide blocker. The waveguide blocker may include a parabolic curved surface in a central portion of a first side of the waveguide blocker, the first side having a slope angle of approximately 45 degrees. The waveguide blocker may be configured to reduce electromagnetic radiation from the waveguide core and recycle scattered fields emitted from the NFT to mitigate thermal background at the recording medium, improving thermal gradients and increasing the area density capacity (ADC) of the hard disk drive write head.

[0007] In a first exemplary embodiment, a near-field transducer (NFT) for a hard disk drive write head is provided. The NFT may include a main pole (MP), a double-layer transducer disposed adjacent to the MP, a waveguide core, and a waveguide blocker disposed adjacent to the waveguide core. The waveguide blocker may include a parabolic shape having a surface configured to be exposed to an ABS surface of the write head. The waveguide blocker may be configured to reduce electromagnetic radiation from the waveguide core and recycle scattered fields emitted from the NFT to mitigate thermal background at the recording medium and improve thermal gradients to increase areal density capacity (ADC) of the hard disk drive write head.

[0008] In some examples, the waveguide blocker comprises a parabolic curved surface at a central portion of the first side of the waveguide blocker. In some examples, the surface is defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker.

[0009] In some examples, the first side of the waveguide blocker has a tilt angle WGBa in the range of 10 to 90 degrees. In some examples, the waveguide blocker comprises at least in part rhodium, iridium, gold, silver, or ruthenium.

[0010] In some examples, the waveguide blocker includes a ruthenium layer disposed on both the leading shield layer and the silicon dioxide (SiO 2 ) layer. In some cases, either the ruthenium layer or the SiO2 layer is tapered to about 45 degrees as part of the ion beam etching and photoresist masking process.

[0011] In some instances, a full film of SiO2 is disposed over the ruthenium layer. In some examples, the waveguide core comprises tantalum oxide (TaOx) and is disposed on a full film of SiO2 adjacent to a ruthenium layer.

[0012] In another exemplary embodiment, a method for fabricating a waveguide blocker for a near-field transducer (NFT) of a write head is provided. The method may include disposing a metal layer over a leading shield and a SiO2 layer. The method may also include disposing photoresist over a portion of the metal layer. The method may also include forming the photoresist into a parabolic shape and etching a portion of the metal layer to form tapered sides of the metal layer at an angle of approximately 10 to 90 degrees. The method may also include disposing a full film of SiO2 over the metal layer.

[0013] In some examples, the method may also include forming a waveguide core adjacent to the full film of SiO 2 , where the waveguide core comprises tantalum oxide (TaOx). In some examples, the method may also include performing a chemical mechanical planarization (CMP) process to planarize the waveguide core to form a flat surface on the waveguide core.

[0014] In some examples, the metal layer comprises either ruthenium or rhodium. In some examples, the waveguide blocker includes a parabolic shape having a surface configured to be exposed to the ABS surface of the write head, and the waveguide blocker is configured to reduce electromagnetic radiation from the waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background in the recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the hard disk drive write head.

[0015] In some examples, the method may also include disposing a bilayer transducer and a main pole over the waveguide core and / or waveguide blocker to form an NFT. In another exemplary embodiment, a waveguide blocker for a write head is provided. The waveguide blocker may include a first side tapered at an angle of approximately 45 degrees. The waveguide blocker may include a parabolic portion centrally disposed on the first side of the waveguide blocker, the waveguide blocker configured to reduce electromagnetic radiation from a waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background at the recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the write head.

[0016] In some examples, the parabolic section has a curvature defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker. In some examples, the waveguide blocker includes a ruthenium layer disposed on both the leading shield layer and the silicon dioxide (SiO 2 ) layer.

[0017] In some cases, either the ruthenium layer or the SiO2 layer is tapered to about 45 degrees as part of the ion beam etching and photoresist masking process.

[0018] In some instances, a full film of SiO2 is disposed over the ruthenium layer. Other features and advantages of embodiments of the present invention will be apparent from the accompanying drawings and from the detailed description that follows.

[0019] Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference symbols indicate similar elements and in which: [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a prior art design for a near-field transducer, according to some embodiments. [Figure 2] FIG. 2 is a downtrack diagram of a prior art design of a waveguide blocker, according to some embodiments. [Figure 3A] 1 shows a diagram of an NFT with a parabolic waveguide blocker, according to some embodiments. [Figure 3B] 1 shows a diagram of an NFT with a parabolic waveguide blocker, according to some embodiments. [Figure 3C] 1 shows a diagram of an NFT with a parabolic waveguide blocker, according to some embodiments. [Figure 4A] 1 shows a diagram of an exemplary parabolic waveguide blocker according to some embodiments. [Figure 4B] 1 shows a diagram of an exemplary parabolic waveguide blocker according to some embodiments. [Figure 5A] 10 illustrates an exemplary graphical representation of the effect of parabolic waveguide blocker focal length on HAMR head performance, according to some embodiments. [Figure 5B] 10 illustrates an exemplary graphical representation of the effect of parabolic waveguide blocker focal length on HAMR head performance, according to some embodiments. [Figure 5C] 10 illustrates an exemplary graphical representation of the effect of parabolic waveguide blocker focal length on HAMR head performance, according to some embodiments. [Figure 5D] 10 illustrates an exemplary graphical representation of the effect of parabolic waveguide blocker focal length on HAMR head performance, according to some embodiments. [Figure 6A] 1 illustrates an exemplary heat distribution within a medium produced by a PWB and a NFT with triangular prisms, according to some embodiments. [Figure 6B] 1 illustrates an exemplary heat distribution within a medium produced by a PWB and a NFT with triangular prisms, according to some embodiments. [Figure 7] FIG. 7 is a diagram of an exemplary thermal distribution spatial difference normalized to peak temperature, according to some embodiments. [Figure 8A] 1 shows a diagram of an exemplary process for fabricating a parabolic waveguide blocker as described herein. [Figure 8B] 1 shows a diagram of an exemplary process for fabricating a parabolic waveguide blocker as described herein. [Figure 8C] 1 shows a diagram of an exemplary process for fabricating a parabolic waveguide blocker as described herein. [Figure 8D] 1 shows a diagram of an exemplary process for fabricating a parabolic waveguide blocker as described herein. DETAILED DESCRIPTION OF THE INVENTION

[0021] A disk drive may include a write head for interacting with a magnetic recording medium to read and write digital data to the magnetic recording medium. As the amount of digital data that needs to be stored increases and the data areal density of hard disk drives (HDDs) writing increases, both the write head and the digital data written to the magnetic recording medium generally can be made smaller.

[0022] Thermally assisted magnetic recording (HAMR) is 1 to 10 Tb / inch 2 (1.55-15.5Pb / m 2 HAMR is a magnetic recording technology that can enable recording at data densities of up to 1000 sq ft (1000 sq m). By exploiting the temperature dependence of coercivity, HAMR can convert optical power into localized heating in magnetic recording media, temporarily reducing the switching field required to align the magnetization of media grains. The sharp thermal gradients, which translate into high magnetic gradients, can enable higher data storage densities than those achievable with current state-of-the-art magnetic recording technologies. Because the heat spot size can be much smaller than the diffraction limit of light, plasmonic structures, also known as near-field transducers (NFTs), can be used to achieve the desired confinement of the optical heating.

[0023] In a HAMR recording head, near-field surface plasmon resonance on the NFT can be excited by the waveguide, heating the recording medium. While most of the optical energy can be coupled into the NFT, there may also be some uncoupled optical energy that ultimately radiates into the recording medium as background. This uncoupled light can reduce the confinement of the heat spot and further cause a reduction in the thermal gradient.

[0024] Furthermore, suppressing the optical background can be used to improve the thermal gradient generated by the NFT. While most of the energy in the waveguide core may be coupled to the NFT, it may also contain some uncoupled light propagating within the waveguide. This uncoupled electromagnetic radiation can travel through the waveguide and be emitted in the form of radiant energy that heats the recording medium as a background that coexists with the main heat source generated by the NFT. This background can reduce the overall thermal gradient along both the recording track direction and the cross-track direction. Some designs can include a metal blocker in front of the waveguide core to suppress this background radiant energy to the medium.

[0025] Figure 1 is a cross-sectional view of a prior art design 100. As shown in Figure 1, the design may include a main pole (MP) 102, a bilayer transducer 104, a waveguide 106, and a waveguide blocker 108. The waveguide blocker 108 may include a triangular prism having a tilt angle WGBa (204), a cross-track width (204) of WGBw, and a down-track thickness (208) of WGBt, which may be shown in Figure 2.

[0026] The present embodiment generally relates to the use of a parabolic waveguide shape to improve thermal gradients in a HAMR head. The present embodiment relates to a component of a near-field transducer (NFT) called a parabolic waveguide blocker (PWB). The NFT can be used in a HAMR head that includes a first portion (plasmon generator) that can be made of a metal bilayer structure (a top layer made of a highly thermomechanically stable material such as rhodium (Rh), iridium (Ir), or platinum (Pt), and gold (Au) on the bottom layer) that can reside on a dielectric waveguide core. In front of the waveguide core, the PWB can include a metal structure that is directly exposed to the air bearing surface (ABS), as shown in FIGS. 3A-3B .

[0027] 3A-3C show diagrams of NFTs with parabolic waveguide blockers 300A-300C. For example, as shown in FIG. 3A, the device can include an MP 302, a bilayer transducer 304, a waveguide core 306, and a parabolic waveguide blocker 308. The design can include a novel parabolic shape to reduce background EM radiation to improve thermal gradients in the HAMR. A 3D view of a parabolic waveguide blocker with half the structure shown (e.g., in FIG. 3B) can show a PEB extending inside the ABS on the side of the waveguide core with the same tilt angle WBGa.

[0028] In this structure, the PWB can have a parabolic top surface. The parabolic surface can be expressed as the function y = x^2 / (4*focal), where the focal length of the parabola is in nm and WGBa is the tilt angle, which can be shown in Figure 4B. The PWB can reduce EM radiation from the waveguide and reuse the scattered field from the NFT to help eliminate the thermal background in the recording medium. This improves the thermal gradient on the NFT, increasing the areal density capacity (ADC) of the HAMR head.

[0029] The present design can use a parabolic-shaped waveguide blocker to suppress the waveguide background and use the light-focusing effect of the parabolic surface to recycle this uncoupled light back into the NFT. The PWB structure can be easily checked by FIB cross section and air-bearing surface (ABS) SEM. Some designs can use a triangular prism-shaped waveguide blocker, for example, as shown in Figure 2. The design described herein can use a parabolic shape, for example, as shown in Figure 4B.

[0030] 4A-4B show diagrams of exemplary parabolic waveguide blockers 400A-400B. For example, FIG. 4A shows a top view illustrating angles WGBw, WGBh2, and WGBw2 of the parabolic waveguide blocker. Additionally, in FIG. 4B, a 3D side view of the parabolic waveguide blocker can show angles WGBa and WGBt.

[0031] The HAMR NFT structure as described in Figures 3A-3B may differ from other designs (e.g., the prior art design of Figure 1) in that shape differences on the waveguide blocker exhibit an impact on the HAMR head ADC and reliability as the parabolic focal length is adjusted.

[0032] The structure can have a parabolic-shaped waveguide blocker made of a highly thermomechanically stable material, such as rhodium (Rh) or ruthenium (Ru), which can be present in front of the waveguide core near the ABS instead of a triangular prism-shaped blocker. The parabolic shape can be defined by the focal length PWB_focal, the height of the waveguide blocker in the ABS direction WGBh2, and the width of the waveguide blocker WGBw. From the 3D diagram, the PWB can have a taper angle that forms a tilt angle on the waveguide blocker, defined by the thicknesses WGBa and WGBt.

[0033] Figures 5A-5D show exemplary graphical representations 500A-500D of the effect of parabolic waveguide blocker focal length on HAMR head performance. Figures 5A-5D also show exemplary effects of PWB_focal on head performance and reliability. Figures 5A-5D may also show the effect of PWB_focal on thermal gradients and ADC. Head thermal gradients can be optimized at a focal length of 225 nm, where both down-track and cross-track gradients are maximized. At the same time, areal density capacity can be increased when PWB_focal increases from 50 nm to 225 nm, and then gradually decreased as the focal length continues to increase toward 1 μm. These results may indicate that background electromagnetic radiation can be controlled by changing the parabolic focal length on the waveguide blocker. The reduced EM background can help eliminate thermal background in the recording medium, thus improving thermal gradients.

[0034] 6A-6B show exemplary heat distributions 600A-600B within a medium produced by a PWB and an NFT having triangular prisms, according to some embodiments. 6A-6B may also show the impact of changing PWB_focal on NFT reliability, as represented by temperature increases in critical components in the NFT. A PWB_focal smaller than 225 nm may increase NFT temperature, potentially reducing reliability.

[0035] 6A-6B may further illustrate the heat distribution in a recording medium produced by the NFT. FIG. 6A shows the heat spot produced by an NFT with a PWB design, and FIG. 6B shows the heat spot produced by the same NFT with a triangular prism. The spatial difference in normalized heat distribution inside the recording medium between several designs with a triangular prism-shaped waveguide blocker and the PWB design demonstrates the effect of thermal background reduction.

[0036] To clarify the spatial difference in thermal distribution, FIG. 7 uses a triangular prism as a reference and shows the normalized difference between a PWB and a triangular prism. FIG. 7 is a diagram of an exemplary thermal distribution spatial difference normalized to the peak temperature of the recording layer 700. As shown in FIG. 7, the thermal background can be eliminated in the area surrounding the NFT region. The maximum background reduction can be ∼25% near the waveguide blocker region and ∼10% near the NFT compared to the baseline. Reducing the thermal background around the NFT can improve the thermal gradient on the HAMR head.

[0037] 8A-8D show diagrams 800A-800D of an exemplary process for fabricating a parabolic waveguide blocker as described herein. As shown in FIG. 8A, a first diagram 800A can show a Ru layer 802 disposed on a leading shield (LS) 804 and a silicon dioxide (SiO2) layer 806.

[0038] 8B, a photoresist (PR) coating and ion beam etching (IBE) process can be performed, which may include applying a layer of photoresist (PR) 808 on the Ru layer 802. The PR 808 is shaped into a parabolic shape, and then ion beam etching (IBE) can be used to create tapered features on the Ru layer 802, the LS 804, and / or the SiO2 806, with an approximate taper angle of about 45 degrees.

[0039] Diagram 800C in FIG. 8C may show the resist (808) being removed to form a parabolic-shaped waveguide blocker. Additionally, the diagram in FIG. 8D may show a silicon dioxide (SiO2) and tantalum oxide (TaOx) deposition process. This may include depositing a full film of silicon dioxide (SiO2) 812, followed by deposition of tantalum oxide (TaOx) 810 to serve as the waveguide (WvG) core. In some examples, chemical mechanical planarization (CMP) may be performed to planarize the TaOx topography to ensure a smooth, uniform surface. Final fabrication steps may be performed to fabricate the WvG, NFT, and magnetic devices to complete the overall structure.

[0040] In a first exemplary embodiment, a near-field transducer (NFT) for a hard disk drive write head is provided. The NFT may include a main pole (MP), a bilayer transducer disposed adjacent to the MP, a waveguide core, and a waveguide blocker disposed adjacent to the waveguide core. The waveguide blocker may include a parabolic shape having a surface configured to be exposed to an ABS surface of the write head. The waveguide blocker may be configured to reduce electromagnetic radiation from the waveguide core and recycle scattered fields emitted from the NFT to mitigate thermal background at the recording medium, improving thermal gradients and increasing areal density capacity (ADC) of the hard disk drive write head.

[0041] In some examples, the waveguide blocker comprises a parabolic curved surface at a central portion of the first side of the waveguide blocker. In some examples, the surface is defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker.

[0042] In some examples, the first side of the waveguide blocker has a slope angle WGBa of about 45 degrees. In some examples, the waveguide blocker comprises at least in part rhodium or ruthenium.

[0043] In some examples, the waveguide blocker includes a ruthenium layer disposed on both the leading shield layer and the silicon dioxide (SiO 2 ) layer. In some cases, either the ruthenium layer or the SiO2 layer is tapered to about 45 degrees as part of the ion beam etching and photoresist masking process.

[0044] In some instances, a full film of SiO2 is disposed over the ruthenium layer. In some examples, the waveguide core comprises tantalum oxide (TaOx) and is disposed on a full film of SiO2 adjacent to a ruthenium layer.

[0045] In another exemplary embodiment, a method for fabricating a waveguide blocker for a near-field transducer (NFT) of a write head is provided. The method may include disposing a metal layer over a leading shield and a SiO2 layer. The method may also include disposing photoresist over a portion of the metal layer. The method may also include forming the photoresist into a parabolic shape and etching a portion of the metal layer to form tapered sides of the metal layer at an angle of approximately 45 degrees. The method may also include disposing a full film of SiO2 over the metal layer.

[0046] In some examples, the method may also include forming a waveguide core adjacent to the full film of SiO 2 , where the waveguide core comprises tantalum oxide (TaOx). In some examples, the method may also include performing a chemical mechanical planarization (CMP) process to planarize the waveguide core to form a flat surface on the waveguide core.

[0047] In some examples, the metal layer comprises either ruthenium or rhodium. In some examples, the waveguide blocker includes a parabolic shape having a surface configured to be exposed to the ABS surface of the write head, and the waveguide blocker is configured to reduce electromagnetic radiation from the waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background in the recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the hard disk drive write head.

[0048] In some examples, the method may also include disposing a bilayer transducer and a main pole over the waveguide core and / or waveguide blocker to form an NFT. In another exemplary embodiment, a waveguide blocker for a write head is provided. The waveguide blocker may include a first side tapered at an angle of approximately 45 degrees. The waveguide blocker may include a parabolic portion centrally disposed on the first side of the waveguide blocker, the waveguide blocker configured to reduce electromagnetic radiation from a waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background at the recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the write head.

[0049] In some examples, the parabolic section has a curvature defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker. In some examples, the waveguide blocker includes a ruthenium layer disposed on both the leading shield layer and the silicon dioxide (SiO 2 ) layer.

[0050] In some cases, either the ruthenium layer or the SiO2 layer is tapered to about 45 degrees as part of the ion beam etching and photoresist masking process.

[0051] In some instances, a full film of SiO2 is disposed over the ruthenium layer. As used herein, terms such as "top," "bottom," "up," "down," and x-, y-, and z-directions will be understood as terms of convenience indicating the spatial relationships of parts relative to one another, rather than specific spatial or gravitational directions. These terms are therefore intended to encompass an assembly of components regardless of whether the assembly is oriented in the specific orientation shown in the drawings and described in the specification, whether oriented upside down from that orientation, or in any other rotational orientation.

[0052] It will be understood that the term "the present invention," as used herein, should not be interpreted to mean that only a single invention having a single essential element or group of elements is presented. Likewise, it will be understood that the term "the present invention" encompasses several separate innovations, each of which can be considered a separate invention. While the present invention has been described in detail with reference to preferred embodiments and drawings thereof, it will be apparent to those skilled in the art that various adaptations and modifications of the embodiments of the present invention can be made without departing from the spirit and scope of the invention. Accordingly, it will be understood that the above detailed description and accompanying drawings are not intended to limit the breadth of the present invention, but that the invention should be inferred solely from the appended claims and their appropriately interpreted legal equivalents.

Claims

1. 1. A near field transducer (NFT) for a hard disk drive write head, comprising: a main pole (MP); a bilayer transducer positioned adjacent to the MP; a waveguide core; a waveguide blocker disposed adjacent to the waveguide core, the waveguide blocker including a parabolic shape having a surface configured to be exposed to an ABS surface of the write head, the waveguide blocker configured to reduce electromagnetic radiation from the waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background at a recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the hard disk drive write head.

2. The NFT of claim 1 , wherein the waveguide blocker comprises a parabolic curved surface at a central portion of a first side of the waveguide blocker.

3. The NFT of claim 2 , wherein the curved surface is defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker.

4. The NFT of claim 2 , wherein the first side of the waveguide blocker has a slope angle WGBa in the range of 10 to 90 degrees.

5. The NFT of claim 1 , wherein the waveguide blocker comprises, at least in part, rhodium, iridium, gold, silver, or ruthenium.

6. 10. The NFT of claim 1, wherein the waveguide blocker includes a ruthenium layer disposed on both a leading shield layer and a silicon dioxide (SiO2) layer.

7. 7. The NFT of claim 6, wherein either the ruthenium layer or the SiO2 layer is tapered in the range of 10 to 90 degrees as part of an ion beam etching and photoresist masking process.

8. The NFT of claim 7 , wherein a full film of SiO 2 is disposed over the ruthenium layer.

9. 10. The NFT of claim 8, wherein the waveguide core comprises tantalum oxide (TaOx) and is disposed on the full film of SiO2 adjacent the ruthenium layer.

10. 1. A method for fabricating a waveguide blocker for a near-field transducer (NFT) of a write head, comprising: disposing a metal layer over the leading shield and the SiO layer; disposing a photoresist over a portion of the metal layer; forming the photoresist into a parabolic shape and etching a portion of the metal layer to form tapered sides of the metal layer at an angle of approximately 45 degrees; and disposing a full film of SiO2 over the metal layer.

11. 11. The method of claim 10, further comprising forming a waveguide core adjacent to the full film of SiO2, the waveguide core comprising tantalum oxide (TaOx).

12. The method of claim 11 , further comprising performing a chemical mechanical planarization (CMP) process to planarize the waveguide core and form a flat surface on the waveguide core.

13. The method of claim 10 , wherein the metal layer comprises either ruthenium or rhodium.

14. 11. The method of claim 10, wherein the waveguide blocker includes a parabolic shape having a surface configured to be exposed to an ABS surface of the write head, and the waveguide blocker is configured to reduce electromagnetic radiation from the waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background at a recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the hard disk drive write head.

15. The method of claim 11 , further comprising disposing a double-layer transducer and a main pole over at least one of the waveguide core and the waveguide blocker to form a NFT.

16. 1. A waveguide blocker for a write head, comprising: a first side tapered at an angle in the range of 10 to 90 degrees; a parabolic portion located at the center of the first side of the waveguide blocker, wherein the waveguide blocker is configured to reduce electromagnetic radiation from a waveguide core, recycle scattered fields emitted from the NFT to mitigate thermal background at a recording medium, and improve thermal gradients to increase areal density capacity (ADC) of the write head.

17. 17. The waveguide blocker of claim 16, wherein the parabolic portion has a curvature defined as a function of y=x^2 / (4*focal), where focal is the focal length of the waveguide blocker.

18. 17. The waveguide blocker of claim 16, wherein the waveguide blocker includes a ruthenium layer disposed on both a leading shield layer and a silicon dioxide (SiO2) layer.

19. 20. The waveguide blocker of claim 18, wherein either the ruthenium layer or the SiO2 layer is tapered between 10 and 90 degrees as part of an ion beam etching and photoresist masking process.

20. 20. The waveguide blocker of claim 19 wherein a full film of SiO2 is disposed over the ruthenium layer.

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