A near field transducer with a peg region, an enlarged region disposed adjacent the peg region, and a barrier material disposed between the peg region and the enlarged region. The barrier material reduces or eliminates interdiffusion of material between the peg region and the enlarged region.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying set of drawings that form a part of the description hereof and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

Various embodiments disclosed herein are generally directed to systems and apparatuses that facilitate coupling a laser diode to a magnetic writer that includes a magnetic write head. In particular, the systems and apparatuses include a plasmonic near-field transducer for heat assisted magnetic recording (HAMR). Plasmonic near-field transducers (NFTs) can generate a large amount of heat in their writing tip also called a “peg” or “peg region”. This heat can negatively impact the operational life of the near-field transducer. Disclosed are apparatuses, systems, and methods directed to increasing NFT operational life by reducing likelihood of peg recession of the writing tip. In particular, disclosed herein are systems, apparatuses, and methods that separate a peg region from the remainder of the NFT by a barrier material. This encapsulation of the peg region (writing tip) from the remainder of the NFT reduces or eliminates interdiffusion of material between the peg region and the remainder of the NFT. The reduction or elimination of interdiffusion of material reduces the likelihood of peg recession. Thus, the near-field transducer can better withstand heat buildup in the peg for HAMR.

The present disclosure relates to HAMR, which can be used to increase areal data density of magnetic media. In a HAMR device, information bits are recorded in a storage layer at elevated temperatures in a specially configured magnetic media. The use of heat can overcome superparamagnetic effects that might otherwise limit the areal data density of the media. As such, HAMR devices may include magnetic write heads for delivering electromagnetic energy to heat a small confined media area (spot size) at the same time the magnetic write head applies a magnetic field to the media for recording.

One way to achieve a tiny confined hot spot is to use an optical near-field transducer (NFT), such as a plasmonic optical antenna or an aperture, located near an air-bearing surface of a hard drive slider. Light may be launched from a light source (e.g., a laser diode) into optics such as a waveguide integrated into the slider. Light propagating in the waveguide may be directed to an optical focusing element, such as a planar solid immersion mirror (PSIM). The PSIM may concentrate the energy into a NFT. The NFT causes the energy to be delivered to the media in a very small spot.

FIG. 1is a perspective view of a hard drive slider that includes a disclosed plasmonic NFT. HAMR slider100includes laser diode102located on top of HAMR slider100proximate to trailing edge surface104of HAMR slider100. Laser diode102delivers light proximate to read/write head106, which has one edge on air-bearing surface108(also referred to as “media-facing surface” or “media interfacing surface”) of HAMR slider100. Air-bearing surface108is held proximate to a moving media surface (not shown) during device operation.

Laser diode102provides electromagnetic energy to heat the media at a point near to read/write head106. Optical coupling components, such as a waveguide110, are formed integrally within HAMR slider100to deliver light from laser diode102to the media. In particular, waveguide110and NFT112may be located proximate read/write head106to provide local heating of the media during write operations. Laser diode102in this example may be an integral, edge-emitting device, although it will be appreciated that waveguide110and NFT112may be used with any light source and light delivery mechanisms. For example, a surface emitting laser (SEL) may be used instead of the edge firing laser illustrated.

While the example inFIG. 1shows laser diode102integrated with HAMR slider100, the NFT112discussed herein may be useful in any type of light delivery configuration. For example, in a free-space light delivery configuration, a laser may be mounted externally to the slider, and coupled to the slider by way of optic fibers and/or waveguides. The slider in such an arrangement may include a grating coupler into which light is coupled and delivered to slider-integrated waveguide110which energizes the NFT112.

The HAMR device utilizes the types of optical devices described above to heat he magnetic recording media (e.g., hard disc) in order to overcome the superparamagnetic effects that limit the areal data density of typical magnetic media. When writing to a HAMR medium, the light can be concentrated into a small hotspot over the track where writing takes place. The light propagates through waveguide110where it is coupled to the NFT112either directly from the waveguide or by way of a focusing element. Other optical elements, such as couplers, mirrors, prisms, etc., may also be formed integral to the slider. The optical elements used in HAMR recording heads are generally referred to as integrated optics devices.

As a result of what is known as the diffraction limit, optical components cannot be used to focus light to a dimension that is less than about half the wavelength of the light. The lasers used in some HAMR designs produce light with wavelengths on the order of 700-1550 nm, yet the desired hot spot is on the order of 50 nm or less. Thus the desired hot spot size is well below half the wavelength of the light. Optical focusers cannot be used to obtain the desired hot spot size, being diffraction limited at this scale. As a result, the NFT112is employed to create a hotspot on the media.

The NFT112is a near-field optics device designed to reach local surface plasmon resonance at a designed wavelength. A waveguide and/or other optical element concentrates light on a transducer region (e.g., focal point) where the NFT112is located. The NFT112is designed to achieve surface plasmon resonance in response to this concentration of light. At resonance, a high electric field surrounds the NFT112due to the collective oscillations of electrons at the metal surface. Part of this field will tunnel into a storage medium and get absorbed, thereby raising the temperature of a spot on the media as it being recorded. NFTs generally have a surface that is made of a material that supports surface plasmons (“plasmonic metal”) such as aluminum, gold, silver, copper, or alloys thereof. They may also have other materials but they must have a material that supports surface plasmons on their outer surface.

FIG. 2is a cross-sectional view shows details of an apparatus200used for HAMR according to an example embodiment. The NFT112is located proximate a media interfacing surface202(e.g., ABS), which is held near a magnetic recording media204during device operation. In the orientation ofFIG. 2, the media interfacing surface202is arranged parallel to the x-z plane. A waveguide206may be disposed proximate the NFT112, which is located at or near the media writing surface214.

The NFT112, waveguide206, and other components are built on a substrate plane, which is parallel to the x-y plane in this view. Waveguide206is shown configured as a planar waveguide, and is surrounded by cladding layers (not shown) that have different indices of refraction than a core of the waveguide206. Other waveguide configurations may be used instead of a planar waveguide, e.g., channel waveguide. Light propagates through the waveguide206. Electrical field lines emanate from the waveguide206and excite the NFT112. The NFT112delivers surface plasmon-enhanced, near-field electromagnetic energy along the negative y-direction where it exits at the media interfacing surface202. This may result in a highly localized hot spot (not shown) on the magnetic recording media204. A magnetic recording pole215that is located alongside NFT112. The magnetic recording pole215generates a magnetic field (e.g., perpendicular field) used in changing the magnetic orientation of the hotspot during writing.

Many NFT designs include an enlarged region as well a peg region. The enlarged region will typically comprise substantially 90% or more of the volume of the NFT in some embodiments. Although discussed as a separate region or portion, typically the peg region is integrally fabricated of a same material as the enlarged region. The specific wavelength of light from the laser diode dictates the size of the enlarged region of the NFT and a length of the peg region in order to get optimal (maximum) coupling efficiency of the laser light to the NFT.

As discussed previously, the peg region acts as the writing tip of the NFT while the enlarged region is configured to receive concentrated light from the laser diode/waveguide and is designed to help NFT achieve surface plasmon resonance in response to this concentration of light. The peg region is in optical and/or electrical communication with the enlarged region and creates a focal point for the energy received by the enlarged region.

As is known, temperature increases in the peg region are a challenge for the durability of HAMR devices. A temperature mismatch between the relatively higher temperature peg region and relatively lower temperature enlarged region as well as mechanical stresses are thought to lead to an exchange of material (and vacancies) between the two regions. As used herein, the term “material” additionally includes any vacancies within the material. The temperature mismatch between the two regions as wells as the mechanical stresses are thought to be phenomenon that drive peg deformation and peg recession, which can lead to failure of the HAMR device.

The present disclosure relates to apparatuses, systems, and methods related to an NFT for the HAMR device. In particular, embodiments of the NFT include a peg region that is separated from the remainder of the NFT by a barrier material. This encapsulation of the peg region from the remainder of the NFT reduces or eliminates interdiffusion of material between the peg region and the remainder of the NFT. The reduction or elimination of interdiffusion of material reduces the likelihood of peg recession and failure of the HAMR device.

FIG. 3shows a cross-sectional view of one embodiment of an NFT312.FIG. 3Ais a second cross-sectional view of the NFT312. As illustrated inFIGS. 3 and 3B, the NFT312includes a peg region302, an enlarged region304, and a barrier material306. Additionally, the peg region302includes surfaces308a,308b,308c,and308dand the enlarged region304includes arcuate surface310and bottom surface314.

The enlarged region304is disposed adjacent the peg region302. The barrier material306is disposed between the peg region302and the enlarged region304to reduce or eliminate interdiffusion of materials between the peg region302and the enlarged region304. However, the peg region302remains in optical and/or electrical communication with the enlarged region304.

The peg region302can extend from the enlarged region304toward media-facing surface (e.g., media interfacing surface202inFIG. 2). In the illustrated embodiment, the enlarged region304has a circular disk shape. In the context of describing the shape of the enlarged region304, the term “disk” refers to three-dimensional shapes that include a cylindrical or tapered cylindrical portion, a bottom surface314, and a top surface. Thus, the disk shape can include a truncated conical shape in some instances. The bottom surface314may or may not be arranged in a plane parallel with the top surface. The peg region302and the enlarged region304can be formed from a thin film of plasmonic metal (e.g., aluminum, gold, silver, copper, and combinations or alloys thereof) on a substrate plane of the slider proximate the write pole (e.g., magnetic recording pole215inFIG. 2). In some embodiments, the peg region302and the enlarged region304can be formed from the same material.

The barrier material306is disposed between the peg region302and the enlarged region304, and in particular, is arranged to substantially separate (encapsulate) the peg region302from the enlarged region304. As illustrated inFIGS. 3 and 3A, the barrier material306can be disposed on a portion of the peg region302opposing the surface308a(i.e., a non-media interfacing end of the peg region302). The length, thickness, and other dimensional and physical properties of the barrier material306will depend upon the composition of the peg region and enlarged region and upon the specific wavelength of light from the laser diode. In one embodiment the barrier material306has a thickness of between about 1.0 nm and about 10.0 nm.

As illustrated, the barrier material306disposed along a side of the peg region302can have thicknesses t1that differ from a thickness t2of the barrier material306disposed along a top of the peg region302and/or a thickness t3of the barrier material306disposed along a non-media interfacing back of the peg region302. The barrier material306can be comprised of one or more of ZrN, TiN, Rh, Zr, Hf, Ru, AuN, TaN, Ir, W, Mo, Co, and alloys thereof. It is desirable that barrier material306create a diffusion barrier for Au and other plasmonic metals and have a thermal conductivity greater than about 10 W/m-K in some embodiments. It is also desirable in some instances that barrier material306has appreciable optical figure of merit. Although best described as a layer in some embodiments, barrier material306can include one or more layers or can be a component that is not layered in nature in some instances.

As shown inFIGS. 3 and 3A, the barrier material306encapsulates the peg region302by extending between the arcuate surface310and the bottom surface314of enlarged region304. In the embodiment illustrated, the barrier material306extends along a plane that substantially aligns with surfaces308b,308c,and308dof the peg region302. However, in other embodiments the barrier material306may not substantially align with surfaces308b,308c,and308d.As will be discussed subsequently, the barrier material306is fabricated to be self-aligned using electro-deposition, plasma treatment/annealing, dopant/annealing, and/or plasma treatment/electrochemical processing etc. The self-aligned fabrication methods allow the barrier material306to be disposed substantially only between the peg region302and the enlarged region304according to various embodiments.

FIGS. 4 and 4Ashow another embodiment of an NFT412fabricated using non-self-aligned methods.FIG. 4shows a first cross-sectional view of the NFT412.FIG. 4Ais a second cross-sectional view of the NFT412. As illustrated inFIGS. 4 and 4B, the NFT412includes a peg region402, an enlarged region404, and a barrier material406. Additionally, the peg region402includes surfaces408a,408b,408c,and408dand the enlarged region404includes an arcuate surface410and bottom surface414.

The general characteristics of the NFT412have been previously described in reference to the NFT312ofFIGS. 3 and 3A, and, therefore, will not be described in great detail. However, the embodiment ofFIGS. 4 and 4Adiffers from that ofFIGS. 3 and 3Ain that the barrier material406is disposed between the enlarged region404and the peg region402and is additionally disposed along the arcuate surface410and the bottom surface414of the enlarged region404. InFIGS. 4 and 4A, the barrier material406is fabricated to be non-self-aligned using known lithography methods, e.g. sputtering. The non-self-aligned fabrication methods allow the barrier material406to be disposed between the enlarged region404and the peg region402and along one or more additional surfaces of the enlarged region404.

FIG. 5shows a cross-sectional view of another embodiment of an NFT512and a spacing element516.FIG. 5Ais a second cross-sectional view of the NFT512and the spacing element516. As illustrated inFIGS. 5 and 5A, the NFT512includes a peg region502, an enlarged region504, and a barrier material506. Additionally, the peg region502includes surface508aand the enlarged region504includes arcuate surface510and bottom surface514.

The general characteristics of the NFT512have been previously described in reference to the NFT512ofFIGS. 5 and 5A, and, therefore, will not be described in great detail. However, the embodiment ofFIGS. 5 and 5Adiffers from that ofFIGS. 3 and 3Ain that the barrier material506is disposed between enlarged region504and peg region502and is additionally disposed between the NFT512and the spacing element516. The spacing element516is disposed to interface with the peg region502and extends between the enlarged region504and a pole (e.g., the magnetic recording pole215ofFIG. 2). In the illustrated embodiment, the spacing element516is dispose around several side surfaces (e.g., surfaces308a,308b,and308cinFIGS. 3 and 3A) but does not contact peg region502as barrier material506is disposed therebetween. Thus, only the surface508a,as well as a bottom surface of the peg region502are not encapsulated by the barrier material506. The spacing element516, also called a NFT to pole spacing (“NPS”), can be formed by a deposition process in some instances, and can be comprised of an electrically insulating material. It is also desirable in some instances that spacing element516has appreciable optical figure of merit.

FIG. 6illustrates a one step in a method of fabricating an NFT. As illustrated inFIG. 6, the peg region602is formed using known lithography methods prior to formation of the enlarged region. A sacrificial material620, such as a photoresist, is disposed over a first portion622of the peg region602, leaving a second portion624of the peg region602exposed. A barrier material606is fabricated over the second portion624of the peg region602.

In one embodiment, the barrier material606is fabricated using a vacuum deposition (dc/rf/reactive sputtering, ion beam deposition, evaporation) or an electroplating process that disposes a metal such as Rh, Zr, Hf, Ru, Ir, W, Mo, Co and alloys thereof over one or more surfaces of the second portion624. In another embodiment, the barrier material606is fabricated by applying a nitride forming compound such as Zr, Ti, Au, Ta, W in low concentrations, i.e., <1 by weight %. In some embodiments, nitrides formed with the disclosed compounds act as an effective diffusion barrier when they form stoichiometric nitrides having the lowest achievable resistivity and highest achievable optical figure of merit to the peg region602. The nitride forming compound can be applied as a diffuse dopant or as a layer in the formation of the peg region602. The exposed second portion624containing the nitride forming compound can be annealed in nitrogen or nitrogen plasma at or relatively near atmospheric pressure at a temperature between about 100° C. and about 400° C. for a duration of up to several hours. The annealing process causes the nitride forming compound to form nitrides such as ZrN, TiN, AuN, TaN, WN along the one or more surfaces of the second portion624(i.e., the surfaces exposed to the nitrogen or nitrogen plasma). In yet another embodiment, the barrier material606can be comprised of AuN and is fabricated by annealing the exposed second portion624of the peg region602in nitrogen or nitrogen plasma at or relatively near atmospheric pressure at a temperature between about 100° C. and about 400° C. for a duration of up to several hours. In another embodiment, the barrier material606can be comprised of AuO and is fabricated either electrochemically or by annealing the exposed second portion624of the peg region602in oxygen or oxygen plasma at or relatively near atmospheric pressure at a temperature between about 100° C. and about 400° C. for a duration of up to several hours.

The enlarged region (e.g., the enlarged region304ofFIGS. 3,3A) is formed between the portions of the sacrificial material620. Thus, the enlarged region is disposed adjacent and along the second portion624of the peg region602such that the barrier material606is disposed at least between the second portion624and the enlarged region (not shown inFIG. 6) to reduce interdiffusion between the peg region602and the enlarged region. After formation of the enlarged region604, the sacrificial material620can be removed using lithography processes such as ion milling and other techniques.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof. All references cited within are herein incorporated by reference in their entirety.