Multilayer plasmon generator

A plasmon generator has a front end face located in a medium facing surface of a magnetic head. The plasmon generator includes a metal portion and a multilayer film portion. The metal portion has a bottom surface, a top surface, and an end face facing toward the front end face. The multilayer film portion includes a first metal layer, a second metal layer and an intermediate layer, and covers the top surface and the end face of the metal portion. The intermediate layer is formed of a material that is higher in Vickers hardness than the metal material used to form the metal portion, the metal material used to form the first metal layer and the metal material used to form the second metal layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasmon generator for use in thermally-assisted magnetic recording in which a recording medium is irradiated with near-field light to lower the coercivity of the recording medium for data writing, and to a thermally-assisted magnetic recording head including the plasmon generator.

2. Description of the Related Art

Recently, magnetic recording devices such as magnetic disk drives have been improved in recording density, and thin-film magnetic heads and recording media of improved performance have been demanded accordingly. Among the thin-film magnetic heads, a composite thin-film magnetic head has been used widely. The composite thin-film magnetic head has such a structure that a read head unit including a magnetoresistive element (hereinafter, also referred to as MR element) for reading and a write head unit including an induction-type electromagnetic transducer for writing are stacked on a substrate. In a magnetic disk drive, a thin-film magnetic head is mounted on a slider that flies slightly above the surface of the magnetic recording medium.

To increase the recording density of a magnetic recording device, it is effective to make the magnetic fine particles of the recording medium smaller. Making the magnetic fine particles smaller, however, causes the problem that the magnetic fine particles drop in the thermal stability of magnetization. To solve this problem, it is effective to increase the anisotropic energy of the magnetic fine particles. However, increasing the anisotropic energy of the magnetic fine particles leads to an increase in coercivity of the recording medium, and this makes it difficult to perform data writing with existing magnetic heads.

To solve the foregoing problems, there has been proposed a technology so-called thermally-assisted magnetic recording. The technology uses a recording medium having high coercivity. When writing data, a write magnetic field and heat are simultaneously applied to the area of the recording medium where to write data, so that the area rises in temperature and drops in coercivity for data writing. The area where data is written subsequently falls in temperature and rises in coercivity to increase the thermal stability of magnetization. Hereinafter, a magnetic head for use in thermally-assisted magnetic recording will be referred to as a thermally-assisted magnetic recording head.

In thermally-assisted magnetic recording, near-field light is typically used as a means for applying heat to the recording medium. A known method for generating near-field light is to use a plasmon generator, which is a piece of metal that generates near-field light from plasmons excited by irradiation with laser light. The laser light to be used for generating near-field light is typically guided through a waveguide, which is provided in the slider, to the plasmon generator disposed near a medium facing surface of the slider.

The plasmon generator has a front end face located in the medium facing surface. The front end face generates near-field light. Surface plasmons are excited on the plasmon generator and propagate along the surface of the plasmon generator to reach the front end face. As a result, the surface plasmons concentrate at the front end face, and near-field light is generated from the front end face based on the surface plasmons.

U.S. Patent Application Publication No. 2011/0170381 A1 discloses a technology in which the surface of a waveguide and the surface of a metallic structure (plasmon generator) are arranged to face each other with a gap therebetween, and evanescent light that occurs at the surface of the waveguide based on the light propagating through the waveguide is used to excite surface plasmons on the metallic structure, so that near-field light is generated based on the excited surface plasmons. Further, U.S. Patent Application Publication No. 2011/0170381 A1 discloses forming a part of the metallic structure from a material different from that of other parts of the metallic structure.

Materials that are typically employed for plasmon generators are metals having high electrical conductivities, such as Au and Ag. However, Au and Ag are relatively soft and have relatively high thermal expansion coefficients. Thus, the following problems arise if a plasmon generator is formed entirely of Au or Ag.

In the process of manufacturing a thermally-assisted magnetic recording head, the medium facing surface is formed by polishing. During polishing, polishing residues of metal materials may grow to cause smears. To remove the smears, the polished surface is slightly etched by, for example, ion beam etching in some cases. If the plasmon generator is formed entirely of Au or Ag, which are relatively soft, the polishing and etching mentioned above may cause the front end face of the plasmon generator to be significantly recessed relative to the other parts of the medium facing surface. In such a case, the front end face of the plasmon generator becomes distant from the recording medium, and the heating performance of the plasmon generator is thus degraded.

Part of the energy of light guided to the plasmon generator through the waveguide is transformed into heat in the plasmon generator. Part of the energy of near-field light generated by the plasmon generator is also transformed into heat in the plasmon generator. The plasmon generator thus rises in temperature during the operation of the thermally-assisted magnetic recording head. If the plasmon generator is formed entirely of Au or Ag, the rise in temperature of the plasmon generator causes the plasmon generator to expand and significantly protrude toward the recording medium. This in turn may cause a protective film covering the medium facing surface to come into contact with the recording medium and thereby damage the recording medium or be broken. When the protective film is broken, the plasmon generator may be damaged by contact with the recording medium or may be corroded by contact with high temperature air.

Further, the plasmon generator formed entirely of Au or Ag may be deformed due to aggregation when its temperature rises. In addition, such a plasmon generator expands when its temperature rises and then contracts when its temperature drops. When the plasmon generator undergoes such a process, the front end face of the plasmon generator may be significantly recessed relative to the other parts of the medium facing surface. In such a case, the heating performance of the plasmon generator is degraded as mentioned above.

For the various reasons described above, the plasmon generator formed entirely of Au or Ag has the drawback of being low in reliability.

U.S. Patent Application Publication No. 2011/0170381 A1 discloses a metallic structure composed of a main body and a layer having a greater hardness than the main body (this layer will hereinafter be referred to as the hard layer). In this metallic structure, the main body is not exposed in the medium facing surface, but the hard layer is exposed in the medium facing surface. In this metallic structure, surface plasmons are generated in the main body. The generated surface plasmons propagate to the hard layer, and near-field light is generated from the vertex of the hard layer. This metallic structure has the drawback that there is a great loss of the surface plasmons as they propagate from the main body to the hard layer, and it is thus difficult to allow the surface plasmons to efficiently propagate to the vertex.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a plasmon generator of high reliability that allows surface plasmons to propagate to the front end face efficiently, and to provide a thermally-assisted magnetic recording head having such a plasmon generator.

A plasmon generator of the present invention has a front end face. The plasmon generator includes a metal portion and a multilayer film portion. The metal portion has a bottom surface, a top surface opposite to the bottom surface, and an end face facing toward the front end face. The multilayer film portion includes a first metal layer, a second metal layer and an intermediate layer, and covers the end face and at least part of the top surface of the metal portion. The intermediate layer is interposed between the first metal layer and the second metal layer. Each of the first metal layer, the second metal layer and the intermediate layer has an end located in the front end face. Each of the metal portion, the first metal layer and the second metal layer is formed of a metal material. The intermediate layer is formed of a material that is higher in Vickers hardness than the metal material used to form the metal portion, the metal material used to form the first metal layer and the metal material used to form the second metal layer. The metal portion is greater in thickness than the first metal layer, the second metal layer and the intermediate layer. The plasmon generator is configured so that a surface plasmon is excited on the bottom surface of the metal portion through coupling with evanescent light generated from a core through which light propagates, and the front end face generates near-field light based on the surface plasmon.

A thermally-assisted magnetic recording head of the present invention includes a medium facing surface facing a recording medium, a main pole producing a write magnetic field for writing data on the recording medium, a waveguide, and a plasmon generator. The waveguide includes a core through which light propagates, and a cladding provided around the core. The plasmon generator has a front end face located in the medium facing surface.

In the thermally-assisted magnetic recording head of the present invention, the plasmon generator includes a metal portion and a multilayer film portion. The metal portion has a bottom surface, a top surface opposite to the bottom surface, and an end face facing toward the front end face. The multilayer film portion includes a first metal layer, a second metal layer and an intermediate layer, and covers the end face and at least part of the top surface of the metal portion. The intermediate layer is interposed between the first metal layer and the second metal layer. Each of the first metal layer, the second metal layer and the intermediate layer has an end located in the front end face. Each of the metal portion, the first metal layer and the second metal layer is formed of a metal material. The intermediate layer is formed of a material that is higher in Vickers hardness than the metal material used to form the metal portion, the metal material used to form the first metal layer and the metal material used to form the second metal layer. The metal portion is greater in thickness than the first metal layer, the second metal layer and the intermediate layer. The plasmon generator is configured so that a surface plasmon is excited on the bottom surface of the metal portion through coupling with evanescent light generated from the core, and the front end face generates near-field light based on the surface plasmon.

In the plasmon generator and the thermally-assisted magnetic recording head of the present invention, the end face of the metal portion may be inclined relative to the front end face.

The plasmon generator of the present invention and the plasmon generator in the thermally-assisted magnetic recording head of the present invention may further include a metal film formed of a metal material and stacked on the multilayer film portion. In such a case, the metal film has an end located in the front end face.

In the plasmon generator and the thermally-assisted magnetic recording head of the present invention, the metal portion may have a first end farthest from the front end face, and the multilayer film portion may have a second end farthest from the front end face. In such a case, the distance from the front end face to the second end may be smaller than the distance from the front end face to the first end. Furthermore, in this case, the plasmon generator may further include a metal film formed of a metal material and disposed on a part of the top surface of the metal portion that is located farther from the front end face than is the second end.

In the plasmon generator and the thermally-assisted magnetic recording head of the present invention, no part of the metal portion may constitute any part of the front end face.

In the plasmon generator and the thermally-assisted magnetic recording head of the present invention, the intermediate layer may be smaller in thickness than the first and second metal layers. The material used to form the intermediate layer may be a metal material different from the metal material used to form the metal portion, the metal material used to form the first metal layer and the metal material used to form the second metal layer, or may be a dielectric material.

In the thermally-assisted magnetic recording head of the present invention, the core may have an evanescent light generating surface that generates evanescent light based on the light propagating through the core. In such a case, the cladding may include an interposition part interposed between the evanescent light generating surface and the bottom surface of the metal portion.

A method of manufacturing the plasmon generator of the present invention includes the steps of: forming an initial metal portion that later becomes the metal portion; forming a multilayer film to cover at least part of the initial metal portion, the multilayer film becoming the multilayer film portion later; and patterning the initial metal portion and the multilayer film so that the initial metal portion is made into the metal portion and the multilayer film is made into the multilayer film portion.

The method of manufacturing the plasmon generator of the present invention may further include the step of forming a metal film on the multilayer film between the step of forming the multilayer film and the step of patterning, the metal film having a thickness equal to or greater than the thickness of the initial metal portion, and the step of planarizing top surfaces of the metal film and the multilayer film between the step of forming the metal film and the step of patterning. In such a case, the initial metal portion, the multilayer film and the metal film are patterned in the step of patterning. Furthermore, in this case, the method of manufacturing the plasmon generator may further include the step of removing at least part of the metal film after the step of patterning.

The present invention makes it possible to provide a plasmon generator of high reliability that allows surface plasmons to propagate to the front end face efficiently, and to provide a thermally-assisted magnetic recording head having such a plasmon generator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Preferred embodiments of the present invention will now be described in detail with reference to the drawings. First, reference is made toFIG. 5andFIG. 6to describe the configuration of a thermally-assisted magnetic recording head according to a first embodiment of the invention. The thermally-assisted magnetic recording head according to the present embodiment includes a plasmon generator according to the present embodiment.FIG. 5is a cross-sectional view showing the configuration of the thermally-assisted magnetic recording head.FIG. 6is a front view showing the medium facing surface of the thermally-assisted magnetic recording head.

The thermally-assisted magnetic recording head according to the present embodiment is for use in perpendicular magnetic recording, and is in the form of a slider to fly over the surface of a rotating recording medium. When the recording medium rotates, an airflow passing between the recording medium and the slider causes a lift to be exerted on the slider. The slider is configured to fly over the surface of the recording medium by means of the lift.

As shown inFIG. 5, the thermally-assisted magnetic recording head has a medium facing surface60facing a recording medium80. Here, X direction, Y direction, and Z direction will be defined as follows. The X direction is the direction across the tracks of the recording medium80, i.e., the track width direction. The Y direction is a direction perpendicular to the medium facing surface60. The Z direction is the direction of travel of the recording medium80as viewed from the slider. The X, Y, and Z directions are orthogonal to one another.

As shown inFIG. 5andFIG. 6, the thermally-assisted magnetic recording head includes: a substrate1formed of a ceramic material such as aluminum oxide-titanium carbide (Al2O3—TiC) and having a top surface1a; an insulating layer2formed of an insulating material such as alumina (Al2O3) and disposed on the top surface1aof the substrate1; a bottom shield layer3formed of a magnetic material and disposed on the insulating layer2; a bottom shield gap film4which is an insulating film disposed to cover the bottom shield layer3; a magnetoresistive (MR) element5serving as a read element disposed on the bottom shield gap film4; two leads (not illustrated) connected to the MR element5; a top shield gap film6which is an insulating film disposed on the MR element5; and a top shield layer7formed of a magnetic material and disposed on the top shield gap film6. The Z direction is also a direction perpendicular to the top surface1aof the substrate1.

An end of the MR element5is located in the medium facing surface60. The MR element5may be an element formed of a magneto-sensitive film that exhibits a magnetoresistive effect, such as an anisotropic magnetoresistive (AMR) element, a giant magnetoresistive (GMR) element, or a tunneling magnetoresistive (TMR) element. The GMR element may be of either the current-in-plane (CIP) type in which a current used for detecting magnetic signals is fed in a direction generally parallel to the plane of layers constituting the GMR element or the current-perpendicular-to-plane (CPP) type in which the current used for detecting magnetic signals is fed in a direction generally perpendicular to the plane of layers constituting the GMR element.

The parts from the bottom shield layer3to the top shield layer7constitute a read head unit. The thermally-assisted magnetic recording head further includes an insulating layer8disposed on the top shield layer7, a middle shield layer9formed of a magnetic material and disposed on the insulating layer8, and a nonmagnetic layer10formed of a nonmagnetic material and disposed on the middle shield layer9. The insulating layer8and the nonmagnetic layer10are formed of alumina, for example.

The thermally-assisted magnetic recording head further includes a yoke layer11formed of a magnetic material and disposed on the nonmagnetic layer10, and an insulating layer12disposed on the nonmagnetic layer10and surrounding the yoke layer11. The yoke layer11has an end face located in the medium facing surface60. The insulating layer12is formed of alumina, for example.

The thermally-assisted magnetic recording head further includes a shield layer13located close to the medium facing surface60and lying on the yoke layer11, and a first coupling portion14and a second coupling portion15disposed away from the medium facing surface60and lying on the yoke layer11. Each of the shield layer13, the first coupling portion14and the second coupling portion15is formed of a magnetic material. The shield layer13has an end face located in the medium facing surface60. Each of the coupling portions14and15includes a first layer, a second layer and a third layer.

The thermally-assisted magnetic recording head further includes a waveguide. The waveguide includes a core17through which light propagates, and a cladding provided around the core17. The cladding includes cladding layers16,18and19. The cladding layer16is disposed to cover the yoke layer11, the insulating layer12and the shield layer13. The core17lies on the cladding layer16. The cladding layer18lies on the cladding layer16and surrounds the core17. The cladding layer19is disposed over the core17and the cladding layer18.

The core17is formed of a dielectric material that transmits laser light to be used for generating near-field light. The laser light emitted from a laser diode (not illustrated) enters the core17and propagates through the core17. The cladding layers16,18and19are each formed of a dielectric material that has a refractive index lower than that of the core17. For example, the core17may be formed of tantalum oxide such as Ta2O5or silicon oxynitride (SiON), while the cladding layers16,18and19may be formed of silicon dioxide (SiO2) or alumina.

Parts of the first and second coupling portions14and15are embedded in the cladding layers16,18and19. The first coupling portion14and the second coupling portion15are located on opposite sides of the core17in the track width direction (the X direction), each being at a distance from the core17.

The thermally-assisted magnetic recording head further includes a plasmon generator40located near the medium facing surface60and lying on the cladding layer19, and a dielectric layer20lying on the cladding layer19and surrounding the plasmon generator40. The plasmon generator40is configured to excite surface plasmons on the principle to be described later. The dielectric layer20is formed of the same material as the cladding layers16,18and19, for example. The plasmon generator40will be described in detail later.

The thermally-assisted magnetic recording head further includes a dielectric layer22lying on the plasmon generator40and the dielectric layer20, and a dielectric layer23disposed to cover the plasmon generator40and the dielectric layer22. The dielectric layer22has an end face closest to the medium facing surface60. The distance from the medium facing surface60to an arbitrary point on the aforementioned end face of the dielectric layer22decreases with decreasing distance from the arbitrary point to the top surface1aof the substrate1. The dielectric layer22is formed of the same material as the cladding layers16,18and19, for example. The dielectric layer23is formed of alumina, for example. The remainder of the first and second coupling portions14and15are embedded in the dielectric layers20,22and23.

The thermally-assisted magnetic recording head further includes a main pole24disposed on the dielectric layer23with the plasmon generator40interposed between the core17and the main pole24, and a coupling layer25disposed over the first and second coupling portions14and15and the dielectric layer23. The thermally-assisted magnetic recording head further includes a coupling layer31disposed on the main pole24, and a coupling layer32disposed on the coupling layer25. Each of the main pole24and the coupling layers25,31and32is formed of a magnetic material.

The main pole24has an end face24alocated in the medium facing surface60. The main pole24may include a narrow portion having the end face24aand an end opposite to the end face24a, and a wide portion connected to the end of the narrow portion. The wide portion is greater than the narrow portion in width in the track width direction (the X direction). The coupling layer31has an end face facing toward the medium facing surface60. The distance from the medium facing surface60to an arbitrary point on this end face decreases with decreasing distance from the arbitrary point to the top surface1aof the substrate1.

The thermally-assisted magnetic recording head further includes a coil30. The coil30includes a first layer30A and a second layer30B. The first layer30A is wound approximately two turns around the coupling layer25. The second layer30B is wound approximately two turns around the coupling layer32.

The thermally-assisted magnetic recording head further includes insulating layers26,27,28,33,34and35. The insulating layer26isolates the first layer30A of the coil30from the main pole24, the coupling layer25and the dielectric layer23. The insulating layer27is disposed in the space between adjacent turns of the first layer30A. The insulating layer28(seeFIG. 6) is disposed around the main pole24and the first layer30A. The insulating layer33isolates the second layer30B of the coil30from the coupling layers31and32, the first layer30A and the insulating layers26and27. The insulating layer34is disposed in the space between adjacent turns of the second layer30B. The insulating layer35is disposed over the second layer30B and the insulating layers33and34. The insulating layers26,28,33and35are formed of alumina, for example. The insulating layers27and34are formed of a photoresist, for example.

The thermally-assisted magnetic recording head further includes a coupling layer36formed of a magnetic material. The coupling layer36lies on the coupling layers31and32and the insulating layer35, and magnetically couples the coupling layers31and32to each other. The coupling layer36has an end face facing toward the medium facing surface60. The distance from the medium facing surface60to an arbitrary point on this end face decreases with decreasing distance from the arbitrary point to the top surface1aof the substrate1. The end face of the coupling layer36is contiguous with the end face of the coupling layer31.

The thermally-assisted magnetic recording head further includes: an insulating layer37disposed between the end face of the coupling layer31and the medium facing surface60and around the second layer30B and the coupling layer36; and a protective layer38disposed to cover the coupling layer36and the insulating layer37. The insulating layer37and the protective layer38are formed of alumina, for example.

The parts from the yoke layer11to the coupling layer36constitute a write head unit. The coil30produces a magnetic field corresponding to data to be written on a recording medium. The shield layer13, the yoke layer11, the coupling portions14and15, the coupling layers25,32,36and31, and the main pole24form a magnetic path for passing a magnetic flux corresponding to the magnetic field produced by the coil30. The main pole24allows the magnetic flux corresponding to the magnetic field produced by the coil30to pass, and produces a write magnetic field for writing data on the recording medium by means of a perpendicular magnetic recording system.

As has been described, the thermally-assisted magnetic recording head according to the present embodiment includes the medium facing surface60, the read head unit, and the write head unit. The read head unit and the write head unit are stacked on the substrate1. The write head unit is located on the front side in the direction of travel of the recording medium80(the Z direction), i.e., on the trailing side, relative to the read head unit.

The thermally-assisted magnetic recording head may include a protective film covering the medium facing surface60. The protective film is formed of diamond-like-carbon (DLC) or Ta2O5, for example. The protective film is not an essential component of the thermally-assisted magnetic recording head and can be dispensed with.

The write head unit includes the coil30, the main pole24, the waveguide, and the plasmon generator40. The waveguide includes the core17and the cladding. The cladding includes the cladding layers16,18and19. The main pole24is located on the front side in the direction of travel of the recording medium80(the Z direction) relative to the core17. The plasmon generator40is disposed between the core17and the main pole24.

The core17and the plasmon generator40will now be described in detail with reference toFIG. 1toFIG. 4.FIG. 1is a perspective view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.FIG. 2is a cross-sectional view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.FIG. 3is a front view showing part of the medium facing surface60of the thermally-assisted magnetic recording head according to the present embodiment.FIG. 4is a plan view showing the positional relationship between the plasmon generator40and the core17of the waveguide shown inFIG. 1.

The core17has an end face17acloser to the medium facing surface60, an evanescent light generating surface17eor a top surface, a bottom surface17c(seeFIG. 5), and two side surfaces. The end face17amay be located in the medium facing surface60or at a distance from the medium facing surface60.FIG. 1toFIG. 6show an example in which the end face17ais located in the medium facing surface60.

The evanescent light generating surface17egenerates evanescent light based on the light propagating through the core17. The cladding layer19covers the evanescent light generating surface17e.

As shown inFIG. 1andFIG. 2, the plasmon generator40has a front end face40aand a core facing surface40e. The front end face40ais located in the medium facing surface60. The front end face40agenerates near-field light on the principle to be described later. The core facing surface40efaces the evanescent light generating surface17eof the core17.

The plasmon generator40is a multilayer plasmon generator including three or more layers. The plasmon generator40includes a metal portion401and a multilayer film portion402. The metal portion401has a bottom surface401e, a top surface401bopposite to the bottom surface401e, and an end face401afacing toward the front end face40aof the plasmon generator40. The end face401amay be inclined relative to the front end face40a.FIG. 1andFIG. 2show an example in which the end face401ais inclined relative to the front end face40a. In this example, the end face401ahas a first edge401a1closest to the front end face40a, and a second edge401a2farthest from the front end face40a. The bottom surface401eis connected to the end face401aat the first edge401a1. The top surface401bis connected to the end face401aat the second edge401a2. The bottom surface401econstitutes the principal part of the core facing surface40eof the plasmon generator40.

The first edge401a1may or may not be exposed in the front end face40a. In the example shown inFIG. 1andFIG. 2, the first edge401a1is not exposed in the front end face40a, and no part of the metal portion401constitutes any part of the front end face40a. The end face401aforms an angle greater than 0° and equal to or smaller than 90° relative to a direction perpendicular to the front end face40a. The angle preferably falls within the range of 15° to 90°, and more preferably within the range of 30° to 60°.

As shown inFIG. 1andFIG. 2, the multilayer film portion402covers the end face401aand at least part of the top surface401bof the metal portion401. In the example shown inFIG. 1andFIG. 2, the multilayer film portion402covers the whole of the top surface401bof the metal portion401. Further, in this example, part of the multilayer film portion402is interposed between the first edge401a1and the front end face40aand lies on the cladding layer19.

As shown inFIG. 1, the multilayer film portion402includes at least a first metal layer M1, a second metal layer M2, and an intermediate layer N1. The intermediate layer N1is interposed between the first metal layer M1and the second metal layer M2. Each of the first metal layer M1, the second metal layer M2and the intermediate layer N1has an end located in the front end face40a. Each of the metal portion401, the first metal layer M1and the second metal layer M2is formed of a metal material. The intermediate layer N1is formed of a material that is higher in Vickers hardness than the metal material used to form the metal portion401, the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2.

The top surface of a part of the multilayer film portion402that lies on the end face401aof the metal portion401is inclined relative to the front end face40a, like the end face401a. This top surface is contiguous with the end face of the dielectric layer22closest to the medium facing surface60.

The plasmon generator40is configured so that surface plasmons are excited on the bottom surface401eof the metal portion401through coupling with the evanescent light generated from the evanescent light generating surface17eof the core17, and the front end face40agenerates near-field light based on the surface plasmons.

The material used to form the intermediate layer N1may be a metal material different from the metal material used to form the metal portion401, the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2, or may be a dielectric material. In the following, we discuss the case where the intermediate layer N1is formed of a metal material different from the metal material used to form the metal portion401, the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2. Here, the metal material used to form the metal portion401, the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2will each be referred to as a first-type metal material, and the metal material used to form the intermediate layer N1will be referred to as a second-type metal material. The second-type metal material is higher in Vickers hardness than the first-type metal material. The first-type metal material is preferably higher in electrical conductivity than the second-type metal material.

In the example shown inFIG. 1, the first edge401a1of the end face401ais located at a distance from the front end face40a. The first metal layer M1covers the top surface401band the end face401aof the metal portion401. A portion of the first metal layer M1is interposed between the first edge401a1and the front end face40a, and lies on the cladding layer19. The bottom surface of this portion of the first metal layer M1constitutes part of the core facing surface40eof the plasmon generator40. The intermediate layer N1and the second metal layer M2are stacked in this order on the first metal layer M1.

In the example shown inFIG. 1, the multilayer film portion402further includes a second intermediate layer N2, a third metal layer M3, a third intermediate layer N3, a fourth metal layer M4, and a protective layer N4stacked in this order on the second metal layer M2. The metal layers M3and M4are each formed of the first-type metal material. The intermediate layers N2and N3and the protective layer N4are each formed of the second-type metal material. As shown inFIG. 1toFIG. 3, each of the metal layers M1to M4, the intermediate layers N1to N3and the protective layer N4has an end located in the front end face40a. The protective layer N4is provided for preventing diffusion of the material forming the metal layer M4. The protective layer N4is not an essential component of the plasmon generator40, and can be dispensed with.

The first-type metal material can be any of Au, Ag, Al and Cu, for example. The second-type metal material can be any of Ru, Pt, Pd, Zr, Ti, Ta, Ni, W, Cr, NiCr, Cu, TiW, TiN, Mo, Hf, Rb and Rh, for example. When the first-type metal material is Cu, the second-type metal material is other than Cu.

As far as the requirement that the second-type metal material be higher in Vickers hardness than the first-type metal material is satisfied, the materials used to form the metal portion401and the metal layers M1to M4may all be the same or may be different from each other, or some of them may be the same. Likewise, the materials used to form the intermediate layers N1to N3and the protective layer N4may all be the same or may be different from each other, or some of them may be the same.

For example, the first metal layer M1, the intermediate layer N1, and the second metal layer M2may be formed of Au, Ru, and Au, respectively, or of Au, Ru, and Cu, respectively.

The metal portion401is greater in thickness than the metal layers M1to M4and the intermediate layers N1to N3. The intermediate layers N1to N3may be smaller in thickness than the metal layers M1to M4. The thickness of the metal portion401falls within the range of, for example, 3 to 300 nm, and preferably within the range of 80 to 150 nm. The thickness of each of the metal layers M1to M4falls within the range of, for example, 0.5 to 50 nm, and preferably within the range of 0.8 to 30 nm. The thickness of each of the intermediate layers N1to N3and the protective layer N4falls within the range of, for example, 0.2 to 20 nm, and preferably within the range of 0.3 to 1 nm.

As previously mentioned, the intermediate layer N1may be formed of a dielectric material. Likewise, each of the intermediate layers N2and N3and the protective layer N4may also be formed of a dielectric material. For example, each of the intermediate layers N1to N3and the protective layer N4may be formed of any of the following dielectric materials: SiO2; alumina; MgO; ZrO2; ZrN2; amorphous SiC; Ta2O5; and Nb2O5.

As shown inFIG. 2, the core facing surface40eincluding the bottom surface401eof the metal portion401faces the evanescent light generating surface17ewith a predetermined distance therebetween. The cladding layer19includes an interposition part19ainterposed between the evanescent light generating surface17eand the core facing surface40eincluding the bottom surface401eof the metal portion401. Since the cladding layer19is part of the cladding, the cladding can be said to include the interposition part19a. The interposition part19ahas a thickness in the range of, for example, 10 to 100 nm, and preferably in the range of 15 to 50 nm.

As shown inFIG. 1andFIG. 4, the plasmon generator40may include a portion whose width in the X direction decreases toward the front end face40a.

The coil30will now be described in detail with reference toFIG. 7andFIG. 8.FIG. 7is a plan view showing the first layer30A of the coil30.FIG. 8is a plan view showing the second layer30B of the coil30. As shown inFIG. 7, the first layer30A is wound approximately two turns around the coupling layer25. InFIG. 7, the first and second coupling portions14and15connected to the coupling layer25are shown by broken lines. The coil30includes a lead portion30L1connected to one end of the first layer30A. InFIG. 7the boundary between the lead portion30L1and the first layer30A is indicated by a dotted line. The first layer30A has a coil connection30AE provided near the other end of the first layer30A. The first layer30A is wound in a counterclockwise direction from the boundary between the lead portion30L1and the first layer30A to the coil connection30AE.

As shown inFIG. 8, the second layer30B is wound approximately two turns around the coupling layer32. The coil30includes a lead portion30L2connected to one end of the second layer30B. InFIG. 8the boundary between the lead portion30L2and the second layer30B is indicated by a dotted line. The second layer30B has a coil connection30BS provided near the other end of the second layer30B. The second layer30B is wound in a counterclockwise direction from the coil connection30BS to the boundary between the lead portion30L2and the second layer30B. The coil connection30BS penetrates the insulating layer33and is electrically connected to the coil connection30AE.

Now, the principle of generation of near-field light in the present embodiment and the principle of thermally-assisted magnetic recording using near-field light will be described in detail. Laser light emitted from a laser diode (not illustrated) enters the core17. As shown inFIG. 5, the laser light50propagates through the core17toward the medium facing surface60, and reaches the vicinity of the plasmon generator40. In the core17, the laser light50is totally reflected at the evanescent light generating surface17eshown inFIG. 2to generate evanescent light permeating into the interposition part19a. In the plasmon generator40, surface plasmons are excited on the core facing surface40ethrough coupling with the evanescent light. The bottom surface401eof the metal portion401constitutes the principal part of the core facing surface40e. Thus, it is mainly on the bottom surface401eof the metal portion401, a part of the core facing surface40e, that the surface plasmons are excited through coupling with the evanescent light.

The surface plasmons excited mainly on the bottom surface401eof the metal portion401pass through the bottom surface of the first metal layer M1lying between the first edge401a1and the front end face40a, and propagate to the front end face40a. The surface plasmons concentrate at the front end face40a, and the front end face40agenerates near-field light based on the surface plasmons.

The surface plasmons excited mainly on the bottom surface401eof the metal portion401propagate to at least the end of the first metal layer M1located in the front end face40a. Where each of the intermediate layers N1to N3is formed of a metal material, the surface plasmons having propagated to the end of the first metal layer M1can also propagate to the respective ends of the metal layers M2to M4and the intermediate layers N1to N3located in the front end face40a. To allow the front end face40ato generate near-field light of sufficient intensity, the surface plasmons having propagated to the end of the first metal layer M1preferably propagate to at least the end of the second metal layer M2.

Where each of the intermediate layers N1to N3is formed of a dielectric material, surface plasmons can be excited also on the surfaces of the metal layers M2to M4in the following manner. The thicknesses of the intermediate layers N1to N3are sufficiently smaller than the wavelength of light propagating through the core17. Accordingly, where each of the intermediate layers N1to N3is formed of a dielectric material, a transfer of energy occurs between the metal layers M1and M2which are adjacent to each other with the intermediate layer N1interposed therebetween, between the metal layers M2and M3which are adjacent to each other with the intermediate layer N2interposed therebetween, and between the metal layers M3and M4which are adjacent to each other with the intermediate layer N3interposed therebetween. As a result, surface plasmons can be excited also on the surfaces of the metal layers M2to M4. However, the energy of the surface plasmons excited on the surfaces of the metal layers M2to M4is lower than the energy of the surface plasmons excited on the bottom surface401eof the metal portion401.

The near-field light generated from the front end face40ais projected toward the recording medium80, reaches the surface of the recording medium80and heats a part of the magnetic recording layer of the recording medium80. This lowers the coercivity of the part of the magnetic recording layer. In thermally-assisted magnetic recording, the part of the magnetic recording layer with the lowered coercivity is subjected to a write magnetic field produced by the main pole24for data writing.

A method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment will now be described. The method of manufacturing the thermally-assisted magnetic recording head includes the steps of: forming components of a plurality of thermally-assisted magnetic recording heads, except the substrates1, on a wafer that includes portions to become the substrates1of the plurality of thermally-assisted magnetic recording heads, thereby fabricating a substructure including rows of a plurality pre-head portions, the plurality of pre-head portions becoming individual thermally-assisted magnetic recording heads later; and cutting the substructure to separate the plurality of pre-head portions from each other and forming the medium facing surface60for each of the plurality of pre-head portions (this step will be referred to as the step of forming the medium facing surface60). A plurality of thermally-assisted magnetic recording heads are produced in this manner.

The method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment will now be described in more detail with attention focused on a single thermally-assisted magnetic recording head. The method of manufacturing the thermally-assisted magnetic recording head forms the insulating layer2, the bottom shield layer3, and the bottom shield gap film4in this order on the substrate1first. Next, the MR element5and two leads (not illustrated) connected to the MR element5are formed on the bottom shield gap film4. The top shield gap film6is then formed to cover the MR element5and the leads. Next, the top shield layer7, the insulating layer8, the middle shield layer9, and the nonmagnetic layer10are formed in this order on the top shield gap film6.

Then, the yoke layer11is formed on the nonmagnetic layer10. Next, the insulating layer12is formed to cover the yoke layer11. The insulating layer12is then polished by, for example, chemical mechanical polishing (hereinafter referred to as CMP), until the yoke layer11is exposed. Next, the shield layer13and the first layers of the coupling portions14and15are formed on the yoke layer11. Next, the cladding layer16is formed to cover the shield layer13and the first layers of the coupling portions14and15. The cladding layer16is then polished by, for example, CMP, until the first layers of the coupling portions14and15are exposed.

Next, the core17is formed on the cladding layer16. Then, the second layers of the coupling portions14and15are formed on the first layers of the coupling portions14and15, respectively. Next, the cladding layer18is formed over the entire top surface of the stack. The cladding layer18is then polished by, for example, CMP, until the core17and the second layers of the coupling portions14and15are exposed.

Reference is now made toFIG. 9AthroughFIG. 17Bto describe steps to be performed after the polishing of the cladding layer18up to the formation of the main pole24. The following descriptions include the description of a method of manufacturing the plasmon generator40according to the present embodiment.FIG. 9AthroughFIG. 17Beach show a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head. Note that portions located below the core17are omitted fromFIG. 9AthroughFIG. 17B.FIGS. 9A-17Aeach show a cross section that intersects the end face24aof the main pole24and that is perpendicular to the medium facing surface60and the top surface1aof the substrate1.FIGS. 9B-17Beach show a cross section of the stack taken at the position at which the medium facing surface60is to be formed. InFIGS. 9A-17A, the symbol “ABS” indicates the position at which the medium facing surface60is to be formed.

FIG. 9AandFIG. 9Bshow a step that follows the polishing of the cladding layer18. In this step, the cladding layer19is formed over the core17and the cladding layer18.

FIG. 10AandFIG. 10Bshow the next step. In this step, first, a metal film401P, which later becomes the metal portion401, is formed on the cladding layer19by sputtering, for example. Next, a first mask layer101is formed on the metal film401P by sputtering, for example. The first mask layer101is formed of Ta or alumina, for example. Then, a second mask layer102patterned is formed on the first mask layer101. For example, the second mask layer102is formed by patterning a layer of a photoresist by photolithography. A portion of the first mask layer101is then etched by, for example, ion beam etching (hereinafter referred to as IBE), using the second mask layer102as a mask. The second mask layer102is then removed.

FIG. 11AandFIG. 11Bshow the next step. In this step, the metal film401P is taper-etched by, for example, IBE, using the first mask layer101as a mask. The taper-etched metal film401P forms an initial metal portion401Q which later becomes the metal portion401. The initial metal portion401Q has an initial top surface401Qb which later becomes the top surface401bof the metal portion401, and an initial end face401Qa which later becomes the end face401aof the metal portion401. The initial end face401Qa is the surface formed by the aforementioned taper-etching. Then, the first mask layer101is removed.

FIG. 12AandFIG. 12Bshow the next step. In this step, a multilayer film402P, which later becomes the multilayer film portion402, is formed by, for example, sputtering, so as to cover at least part of the initial metal portion401Q. In the present embodiment, the multilayer film402P is formed on the initial top surface401Qb and the initial end face401Qa of the initial metal portion401Q and on the cladding layer19, in particular.

FIG. 13AandFIG. 13Bshow the next step. In this step, first, an etching mask103is formed on the multilayer film402P. The etching mask103is formed by patterning a layer of a photoresist by photolithography, for example. The planar shape (the shape in a plan view) of the etching mask103corresponds to the planar shape of the plasmon generator40. Then, portions of the initial metal portion401Q and the multilayer film402P are etched by, for example, IBE or reactive ion etching (hereinafter referred to as RIE) using the etching mask103, whereby the initial metal portion401Q and the multilayer film402P are patterned. The initial metal portion401Q is patterned into the metal portion401. Patterning the initial metal portion401Q makes the initial top surface401Qb into the top surface401bof the metal portion401, and the initial end face401Qa into the end face401aof the metal portion401. The multilayer film402P is patterned into the multilayer film portion402.

FIG. 15AandFIG. 15Bshow the next step. In this step, first, the dielectric layer20is formed over the entire top surface of the stack. The dielectric layer20is then polished by, for example, CMP, until a part of the multilayer film portion402that lies on the metal portion401is exposed.

FIG. 16AandFIG. 16Bshow the next step. In this step, first, the dielectric layer22is formed over the multilayer film portion402and the dielectric layer20. An etching mask (not illustrated) is then formed on the dielectric layer22. Using this etching mask, the dielectric layers22and20are then taper-etched by IBE, for example. This forms the end face of the dielectric layer22closest to the medium facing surface60and removes a part of the dielectric layer20lying on the multilayer film portion402.

FIG. 17AandFIG. 17Bshow the next step. In this step, first, the dielectric layer23is formed to cover the multilayer film portion402and the dielectric layers20and22. Then, the cladding layer19and the dielectric layers20,22and23are selectively etched to form therein two openings for exposing the respective top surfaces of the second layers of the coupling portions14and15. Next, the third layers of the coupling portions14and15are formed on the second layers of the coupling portions14and15, respectively. Then, the main pole24is formed on the dielectric layer23, and the coupling layer25is formed on the third layers of the coupling portions14and15and the dielectric layer23.

A series of steps from the step shown inFIG. 10AandFIG. 10Bto the step shown inFIG. 16AandFIG. 16Bcorresponds to the method of manufacturing the plasmon generator40according to the present embodiment.

Now, steps to follow the step ofFIG. 17AandFIG. 17Bwill be described with reference toFIG. 5andFIG. 6. First, the insulating layer26is formed. Then, the first layer30A of the coil30is formed on the insulating layer26. The insulating layer27is then formed. Next, the insulating layer28is formed over the entire top surface of the stack. The insulating layer28is then polished by, for example, CMP, until the main pole24, the coupling layer25and the first layer30A are exposed. The top surfaces of the main pole24, the coupling layer25and the insulating layer28are thereby planarized.

Next, the coupling layer31is formed on the main pole24and the coupling layer32is formed on the coupling layer25. The insulating layer33is then formed. Then, an opening for exposing the coil connection30AE of the first layer30A is formed in the insulating layer33. The second layer30B of the coil30is then formed on the insulating layer33. The coil connection SOBS of the second layer30B is disposed on the coil connection30AE. Next, the insulating layers34and35and the coupling layer36are formed in succession. Then, the coupling layers31and36are taper-etched to provide the coupling layers31and36with the respective end faces facing toward the medium facing surface60. Next, the insulating layer37is formed over the entire top surface of the stack. The insulating layer37is then polished by, for example, CMP, until the coupling layer36is exposed. Then, the protective layer38is formed to cover the entire top surface of the stack.

Wiring, terminals, and other components are then formed on the top surface of the protective layer38. When the substructure is completed thus, the step of forming the medium facing surface60is performed. Forming the medium facing surface60provides the multilayer film portion402with the front end face40a. A protective film for covering the medium facing surface60may be formed thereafter. Being provided with the medium facing surface60, each pre-head portion becomes a thermally-assisted magnetic recording head.

The step of forming the medium facing surface60includes the step of polishing the surface that is formed for each pre-head portion by cutting the substructure, and the step of forming a rail on the polished surface for allowing the slider to fly.

In the aforementioned polishing step, the layers exposed in the medium facing surface60may be polished in different amounts due to differences between materials used for those layers, and this may cause irregularities on the medium facing surface60.

Further, in the aforementioned polishing step, polishing residues of the metal materials may grow to cause smears. In order to remove the smears, the step of forming the medium facing surface60may include the step of etching the polished surface slightly by, for example, IBE, after the polishing step.

The effects of the plasmon generator40and the thermally-assisted magnetic recording head according to the present embodiment will now be described. The plasmon generator40according to the present embodiment includes the metal portion401and the multilayer film portion402. The multilayer film portion402includes at least the first metal layer M1, the second metal layer M2and the intermediate layer N1. Each of the first metal layer M1, the second metal layer M2and the intermediate layer N1has an end located in the front end face40aof the plasmon generator40. The intermediate layer N1is interposed between the first metal layer M1and the second metal layer M2. The intermediate layer N1is formed of a material that is higher in Vickers hardness than the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2. This makes it possible to prevent the first metal layer M1and the second metal layer M2sandwiching the intermediate layer N1from being deformed. Further, the plasmon generator40according to the present embodiment achieves higher mechanical strength as a whole when compared with a plasmon generator that is formed only of a single metal layer of the first-type metal material.

The foregoing features of the plasmon generator40according to the present embodiment make it possible to prevent the plasmon generator40from being deformed or damaged, and the front end face40afrom being significantly recessed relative to the other parts of the medium facing surface60in the step of forming the medium facing surface60or due to a temperature change of the plasmon generator40. Consequently, the present embodiment allows for preventing the plasmon generator40from being degraded in heating performance. This benefit is more noticeable when the multilayer film portion402includes one or more pairs of an intermediate layer and a metal layer in addition to the first metal layer M1, the second metal layer M2and the intermediate layer N1.

Further, in the plasmon generator40according to the present embodiment, the metal portion401has the bottom surface401eon which surface plasmons are to be excited, the top surface401b, and the end face401a. The multilayer film portion402covers the top surface401band the end face401aof the metal portion401. The metal portion401is greater in thickness than the metal layers M1to M4and the intermediate layers N1to N3of the multilayer film portion402. Such a configuration allows for sufficient excitation of surface plasmons on the thick metal portion401.

Further, in the present embodiment, there is no difference in level between the bottom surface401eof the metal portion401and the bottom surface of the part of the multilayer film portion402that is interposed between the first edge401a1and the front end face40aand lies on the cladding layer19. The present embodiment thus allows the surface plasmons excited on the bottom surface401eto efficiently propagate to the front end face40acomposed of the respective ends of the layers included in the multilayer film portion402.

In the present embodiment, in particular, the end face401aof the metal portion401is inclined relative to the front end face40aso that the first edge401a1is located closer to the front end face40athan is the second edge401a2. The present embodiment thus makes it possible to bring the edge of the bottom surface401eof the metal portion401closest to the front end face40a, that is, the first edge401a1of the end face401a, into close proximity to the front end face40awhile configuring the respective ends of the layers included in the multilayer film portion402to constitute the front end face40a. This allows the surface plasmons excited on the bottom surface401eto propagate to the front end face40amore efficiently.

Further, in the present embodiment, no part of the metal portion401constitutes any part of the front end face40a. Accordingly, the material for the metal portion401can be selected from any metal materials that have high electrical conductivities and are suitable for excitation and propagation of surface plasmons, without the need for considering mechanical strength. This allows for appropriate excitation and propagation of surface plasmons on the metal portion401.

As can be seen from the foregoing, the present embodiment makes it possible to provide the plasmon generator40having high reliability and allowing surface plasmons to propagate to the front end face40aefficiently, and to provide a thermally-assisted magnetic recording head having the plasmon generator40.

Further, the plasmon generator40according to the present embodiment provides additional effects as described below when configured so that a metal layer in the multilayer film portion402is sandwiched between two intermediate layers. A metal layer is typically formed of a metal polycrystal. In general, when a metal polycrystal gets hot, a plurality of crystal grains constituting the metal polycrystal aggregate and grow, and can thereby cause the metal polycrystal to be deformed. If a metal layer is sandwiched between two intermediate layers, the metal layer is restrained to some extent by the two intermediate layers. In such a case, it is thus possible to prevent the aggregation and growth of the plurality of crystal grains constituting the metal layer (the metal polycrystal) when the metal layer gets hot. This consequently allows for preventing the metal layer from becoming deformed.

Where the first-type metal material is higher in electrical conductivity than the second-type metal material, the intermediate layers N1to N3are preferably smaller in thickness than the metal layers M1to M4. In such a case, it is possible to reduce loss of surface plasmons when the surface plasmons propagate from the end of the metal layer M1located in the front end face40ato the respective ends of the metal layers M2to M4located in the front end face40a.

Second Embodiment

A second embodiment of the invention will now be described. The thermally-assisted magnetic recording head and the plasmon generator40according to the present embodiment are the same in configuration as those according to the first embodiment. The present embodiment differs from the first embodiment in the method of manufacturing the thermally-assisted magnetic recording head, particularly in the method of manufacturing the plasmon generator40.

The method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment will now be described with reference toFIG. 18AthroughFIG. 21B.FIG. 18AthroughFIG. 21Beach show a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head. Note that portions located below the core17are omitted fromFIG. 18AthroughFIG. 21B.FIGS. 18A-21Aeach show a cross section that intersects the end face24aof the main pole24and that is perpendicular to the medium facing surface60and the top surface1aof the substrate1.FIGS. 18B-21Beach show a cross section of the stack taken at the position at which the medium facing surface60is to be formed. InFIGS. 18A-21A, the symbol “ABS” indicates the position at which the medium facing surface60is to be formed.

The method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment are the same as those according to the first embodiment up to the step shown inFIG. 12AandFIG. 12B.

FIG. 18AandFIG. 18Bshow a step to follow the step ofFIG. 12AandFIG. 12B. In this step, a metal film110having a thickness equal to or greater than that of the initial metal portion401Q is formed on the multilayer film402P. The metal film110is formed of a metal material. The metal material used to form the metal film110is preferably the same as the metal material used to form the initial metal portion401Q (the metal portion401).

FIG. 19AandFIG. 19Bshow the next step. In this step, first, the metal film110is polished by, for example, CMP, until a part of the multilayer film402P that lies on the initial metal portion401Q is exposed. The top surfaces of the metal film110and the multilayer film402P are thereby planarized. Next, an etching mask113is formed over the top surfaces of the metal film110and the multilayer film402P. The etching mask113is formed by patterning a layer of a photoresist by photolithography, for example. The planar shape of the etching mask113corresponds to the planar shape of the plasmon generator40. Next, portions of the initial metal portion401Q, the multilayer film402P and the metal film110are etched by, for example, IBE or RIE using the etching mask113, whereby the initial metal portion401Q, the multilayer film402P and the metal film110are patterned. The initial metal portion401Q is patterned into the metal portion401. The multilayer film402P is patterned into the multilayer film portion402. After this step, the metal film110remains on a part of the multilayer film portion402that lies on the end face401aof the metal portion401and the cladding layer19.

FIG. 20AandFIG. 20Bshow the next step. In this step, first, the etching mask113is removed. Next, the dielectric layer20is formed over the entire top surface of the stack. The dielectric layer20is then polished by, for example, CMP, until the part of the multilayer film portion402lying on the metal portion401is exposed.

FIG. 21AandFIG. 21Bshow the next step. In this step, the dielectric layer22is formed over the multilayer film portion402and the dielectric layer20in the same manner as the step shown inFIG. 16AandFIG. 16B. Next, an etching mask (not illustrated) is formed on the dielectric layer22. Then, using this etching mask, the dielectric layers22and20are taper-etched and at least part of the metal film110is removed by IBE, for example. This forms the end face of the dielectric layer22closest to the medium facing surface60. In the present embodiment, in particular, the whole of the metal film110is removed in this step.

A series of steps subsequent to the above-described step in the present embodiment is the same as a series of steps subsequent to the step ofFIG. 16AandFIG. 16Bin the first embodiment.

In the method of manufacturing the plasmon generator40according to the present embodiment, prior to patterning the initial metal portion401Q and the multilayer film402P, the metal film110is formed and the top surfaces of the metal film110and the multilayer film402P are planarized. Thereafter, the initial metal portion401Q, the multilayer film402P and the metal film110are patterned by etching portions of the initial metal portion401Q, the multilayer film402P and the metal film110. Accordingly, in the present embodiment, when etching the portions of the initial metal portion401Q, the multilayer film402P and the metal film110, the structure to be etched is uniform in thickness regardless of position. Further, in this structure, materials and the amount to be etched do not substantially vary from position to position. The present embodiment thus allows for preventing the etching amount from varying from position to position when the portions of the initial metal portion401Q, the multilayer film402P and the metal film110are etched. Consequently, the present embodiment allows for accurately patterning the initial metal portion401Q and the multilayer film402P.

Third Embodiment

A third embodiment of the invention will now be described. First, the configurations of the thermally-assisted magnetic recording head and the plasmon generator40according to the present embodiment will be described with reference toFIG. 22andFIG. 23.FIG. 22is a cross-sectional view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.FIG. 23is a front view showing part of the medium facing surface60of the thermally-assisted magnetic recording head according to the present embodiment.

In the present embodiment, as shown inFIG. 22andFIG. 23, the plasmon generator40includes a metal film110in addition to the metal portion401and the multilayer film portion402. The metal film110is formed of a metal material and stacked on the multilayer film portion402. The metal film110is stacked particularly on the part of the multilayer film portion402lying on the end face401aof the metal portion401and the cladding layer19. The metal film110has an end located in the front end face40a.

Reference is now made toFIG. 24AandFIG. 24Bto describe the method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment.FIG. 24AandFIG. 24Bshow a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head. Note that portions located below the core17are omitted fromFIG. 24AandFIG. 24B.FIG. 24Ashows a cross section that intersects the end face24aof the main pole24and that is perpendicular to the medium facing surface60and the top surface1aof the substrate1.FIG. 24Bshows a cross section of the stack taken at the position at which the medium facing surface60is to be formed. InFIG. 24A, the symbol “ABS” indicates the position at which the medium facing surface60is to be formed.

The method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment are the same as those according to the second embodiment up to the step shown inFIG. 20AandFIG. 20B.

FIG. 24AandFIG. 24Bshow a step to follow the step ofFIG. 20AandFIG. 20B. In this step, the dielectric layer22is formed over the multilayer film portion402and the dielectric layer20in the same manner as the step shown inFIG. 21AandFIG. 21B. Next, an etching mask (not illustrated) is formed on the dielectric layer22. Then, using this etching mask, the dielectric layers22and20are taper-etched and a portion of the metal film110is removed by IBE, for example. As a result, in the present embodiment the metal film110remains on the portion of the multilayer film portion402lying on the end face401aof the metal portion401and the cladding layer19, as shown inFIG. 24A.

A series of steps subsequent to the above-described step in the present embodiment is the same as a series of steps subsequent to the step ofFIG. 16AandFIG. 16Bin the first embodiment.

Fourth Embodiment

A fourth embodiment of the invention will now be described. First, the configurations of the thermally-assisted magnetic recording head and the plasmon generator40according to the present embodiment will be described with reference toFIG. 25.FIG. 25is a cross-sectional view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.

In the present embodiment, as shown inFIG. 25, the metal portion401has a first end401ffarthest from the front end face40a. The multilayer film portion402has a second end402ffarthest from the front end face40a. The distance from the front end face40ato the second end402fis smaller than the distance from the front end face40ato the first end401f.

In the present embodiment, the plasmon generator40includes a metal film120in addition to the metal portion401and the multilayer film portion402. The metal film120is formed of a metal material and disposed on a part of the top surface401bof the metal portion401that is located farther from the front end face40athan is the second end402f. The metal material used to form the metal film120is preferably the first-type metal material described in the first embodiment section.

The metal film120is higher in thermal conductivity than the multilayer film portion402. Thus, the present embodiment allows for easier dissipation of heat generated by the plasmon generator40when compared with the first embodiment, thereby allowing for suppressing a temperature rise of the plasmon generator40.

The method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment will now be described with reference toFIG. 26AthroughFIG. 31B.FIG. 26AthroughFIG. 31Beach show a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head. Note that portions located below the core17are omitted fromFIG. 26AthroughFIG. 31B.FIGS. 26A-31Aeach show a cross section that intersects the end face24aof the main pole24and that is perpendicular to the medium facing surface60and the top surface1aof the substrate1.FIGS. 26B-31Beach show a cross section of the stack taken at the position at which the medium facing surface60is to be formed. InFIGS. 26A-31A, the symbol “ABS” indicates the position at which the medium facing surface60is to be formed.

The method of manufacturing the thermally-assisted magnetic recording head and the method of manufacturing the plasmon generator40according to the present embodiment are the same as those according to the first embodiment up to the step shown inFIG. 11AandFIG. 11B.

FIG. 26AandFIG. 26Bshow a step to follow the step ofFIG. 11AandFIG. 11B. In this step, a multilayer film402P, which later becomes the multilayer film portion402, is formed by, for example, sputtering, so as to cover a part of the initial metal portion401Q. In the present embodiment, the multilayer film402P is formed on a part of the initial top surface401Qb, on the initial end face401Qa and on the cladding layer19, in particular.

FIG. 27AandFIG. 27Bshow the next step. In this step, the metal film120is formed on the initial metal portion401Q and the multilayer film402P into a thickness equal to or greater than that of the initial metal portion401Q. The metal material used to form the metal film120is preferably the same as the metal material used to form the initial metal portion401Q (the metal portion401).

FIG. 28AandFIG. 28Bshow the next step. In this step, first, the metal film120is polished by, for example, CMP, until a part of the multilayer film402P that lies on the initial metal portion401Q is exposed. The top surfaces of the metal film120and the multilayer film402P are thereby planarized. Next, an etching mask123is formed over the top surfaces of the metal film120and the multilayer film402P. The etching mask123is formed by patterning a layer of a photoresist by photolithography, for example. The planar shape of the etching mask123corresponds to the planar shape of the plasmon generator40. Next, portions of the initial metal portion401Q, the multilayer film402P and the metal film120are etched by, for example, IBE or RIE using the etching mask123, whereby the initial metal portion401Q, the multilayer film402P and the metal film120are patterned. The initial metal portion401Q is patterned into the metal portion401. The multilayer film402P is patterned into the multilayer film portion402.

FIG. 29AandFIG. 29Bshow the next step. In this step, first, the etching mask123is removed. Next, the dielectric layer20is formed over the entire top surface of the stack. The dielectric layer20is then polished by, for example, CMP, until a part of the multilayer film portion402that lies on the metal portion401is exposed.

FIG. 30AandFIG. 30Bshow the next step. In this step, first, the dielectric layer22is formed over the multilayer film portion402, the metal film120and the dielectric layer20. Next, an etching mask (not illustrated) is formed on the dielectric layer22. Then, using this etching mask, the dielectric layers22and20are taper-etched and at least part of the metal film120remaining on the multilayer film portion402is removed by IBE, for example. In this step, as in the third embodiment, the metal film120may be allowed to remain on the multilayer film portion402. This step forms the metal film120located on the part of the top surface401bof the metal portion401that is located farther from the front end face40athan is the second end402f.

FIG. 31AandFIG. 31Bshow the next step. In this step, first, the dielectric layer23is formed to cover the multilayer film portion402, the metal film120and the dielectric layers20and22. Then, the cladding layer19and the dielectric layers20,22and23are selectively etched to form therein two openings for exposing the respective top surfaces of the second layers of the coupling portions14and15. Next, the third layers of the coupling portions14and15are formed on the second layers of the coupling portions14and15, respectively. Then, the main pole24is formed on the dielectric layer23, and the coupling layer25is formed on the third layers of the coupling portions14and15and the dielectric layer23. The subsequent steps are the same as those in the first embodiment.

The present invention is not limited to the foregoing embodiments, and various modifications may be made thereto. For example, as far as the requirements of the appended claims are met, the shape of the plasmon generator and the locations of the plasmon generator, the core, and the main pole can be chosen as desired, without being limited to the examples illustrated in the foregoing embodiments.

It is apparent that the present invention can be carried out in various forms and modifications in the light of the foregoing descriptions. Accordingly, within the scope of the following claims and equivalents thereof, the present invention can be carried out in forms other than the foregoing most preferable embodiments.