Thermally-assisted magnetic recording head including a main pole and a plasmon generator

A thermally-assisted magnetic recording head includes a main pole and a plasmon generator. The main pole has a front end face located in the medium facing surface. The plasmon generator has a near-field light generating surface located in the medium facing surface. The front end face of the main pole includes a first end face portion and a second end face portion. The second end face portion is located farther from the near-field light generating surface than is the first end face portion, and is greater than the first end face portion in width in the track width direction. The first end face portion and the near-field light generating surface are equal in width.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermally-assisted magnetic recording head for use in thermally-assisted magnetic recording to write data on a recording medium with the coercivity thereof lowered by irradiating the recording medium with near-field light.

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, the thin-film magnetic head is mounted on a slider configured to slightly fly above the surface of a recording medium. The slider has a medium facing surface configured to face the recording medium. The medium facing surface has an air inflow end (a leading end) and an air outflow end (a trailing end).

Here, the side of the positions closer to the leading end relative to a reference position will be defined as the leading side, and the side of the positions closer to the trailing end relative to the reference position will be defined as the trailing side. The leading side is the rear side in the direction of travel of the recording medium relative to the slider. The trailing side is the front side in the direction of travel of the recording medium relative to the slider.

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 eliminate 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 resolve 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 the medium facing surface of the slider.

U.S. Patent Application Publication No. 2011/0170381 A1 discloses a thermally-assisted magnetic recording head including a main pole, a waveguide and a plasmon generator. The main pole has an end face located in the medium facing surface, and produces a write magnetic field from this end face. The plasmon generator has an end face located in the medium facing surface. The waveguide includes a core and a cladding. In this head, the surface of the core and the surface of the plasmon generator face each other with a gap interposed therebetween. This head is configured to excite surface plasmons on the plasmon generator by using evanescent light that occurs on the surface of the core based on the light propagating through the core, and to cause near-field light to be generated from the end face of the plasmon generator based on the excited surface plasmons.

A thermally-assisted magnetic recording head including a plasmon generator causes a spot of near-field light to be formed on a recording medium by the plasmon generator. The size of the spot of near-field light will hereinafter be referred to as light spot size. It has conventionally been considered that a smaller light spot size is effective for achieving higher recording density.

On the recording medium, the spot of near-field light generates a temperature distribution such that the temperature peaks at the center of the spot, and decreases with increasing distance from the center. Magnetic recording is typically performed on a ring-shaped region on the recording medium, the region having a temperature of 400° C. to 500° C. Hereinafter, a region on the recording medium formed by a combination of the aforementioned ring-shaped region having a temperature of 400° C. to 500° C. and a region on the inner side thereof will be referred to as thermal spot. Conventionally, track width depends on the thermal spot size.

The light spot size can be reduced to the order of 50 nm by downsizing the plasmon generator or reducing the power of the laser light for use to generate near-field light. However, since the heat resulting from near-field light spreads on the recording medium by conduction, the thermal spot size becomes larger than the light spot size. It is thus difficult to sufficiently reduce track width and thereby sufficiently increase recording density with the approach of reducing the light spot size.

U.S. Patent Application Publication No. 2011/0170381 A1 discloses the technique to form a plasmon generator by etching a metal layer using either the main pole or a mask for use to etch the main pole. This technique suffers from the problem that if the end face of the main pole and the end face of the plasmon generator are both reduced in width, the main pole becomes unable to pass much magnetic flux, thus becoming unable to produce a write magnetic field of sufficient magnitude from the end face of the main pole.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thermally-assisted magnetic recording head with a reduced track width and a main pole for producing a write magnetic field of sufficient magnitude, and to provide a method of manufacturing such a thermally-assisted magnetic recording head.

A thermally-assisted magnetic recording head of the present invention includes: a medium facing surface configured to face a recording medium; a coil for producing a magnetic field corresponding to data to be written on the recording medium; a main pole; a waveguide; and a plasmon generator. The main pole has a front end face located in the medium facing surface. The waveguide includes a core and a cladding, the core allowing light to propagate therethrough, the cladding being provided around the core. The plasmon generator has a near-field light generating surface located in the medium facing surface.

The main pole is configured to pass a magnetic flux corresponding to the magnetic field produced by the coil, and to produce from the front end face a write magnetic field for writing data on the recording medium. The plasmon generator is configured to excite a surface plasmon on the plasmon generator based on the light propagating through the core, and to generate near-field light from the near-field light generating surface based on the surface plasmon. The front end face of the main pole and the near-field light generating surface are at locations different from each other in the direction of travel of the recording medium. The front end face of the main pole includes a first end face portion, and a second end face portion contiguous with the first end face portion. The second end face portion is located farther from the near-field light generating surface than is the first end face portion, and is greater than the first end face portion in width in the track width direction. The first end face portion has a first edge and a second edge opposite to each other in the track width direction. The near-field light generating surface has a third edge and a fourth edge opposite to each other in the track width direction. The first edge and the third edge are located on a first imaginary straight line. The second edge and the fourth edge are located on a second imaginary straight line parallel to the first imaginary straight line.

The thermally-assisted magnetic recording head of the present invention may further include a dielectric layer provided between the main pole and the plasmon generator.

In the thermally-assisted magnetic recording head of the present invention, the core may have an evanescent light generating surface for generating evanescent light based on the light propagating through the core, and the plasmon generator may have a plasmon exciting section located at a predetermined distance from the evanescent light generating surface and facing the evanescent light generating surface. In this case, in the plasmon generator, a surface plasmon is excited on the plasmon exciting section through coupling with the evanescent light generated by the evanescent light generating surface, the surface plasmon propagates to the near-field light generating surface, and the near-field light generating surface generates near-field light based on the surface plasmon.

In the thermally-assisted magnetic recording head of the present invention, the front end face of the main pole may be located on the front side in the direction of travel of the recording medium relative to the near-field light generating surface.

In the thermally-assisted magnetic recording head of the present invention, the main pole may include a first layer, and a second layer stacked on the first layer. In this case, the first layer has the first end face portion, and the second layer has the second end face portion.

The first layer may further have a first rear end face portion farthest from the medium facing surface. The second layer may further have a second rear end face portion farthest from the medium facing surface. In this case, the first rear end face portion and the second rear end face portion may be located at the same distance from the medium facing surface.

The thermally-assisted magnetic recording head of the present invention may further include a heat sink having an outer surface. In this case, the plasmon generator may have a top surface including a first region and a second region, the second region being located farther from the medium facing surface than the first region. Further, the first layer of the main pole may have a bottom surface opposed to the first region of the top surface of the plasmon generator, and a first side surface and a second side surface located at opposite ends of the first layer in the track width direction. The second layer of the main pole may have a third side surface and a fourth side surface located at opposite ends of the second layer in the track width direction. The outer surface of the heat sink may include: a first portion opposed to the second region of the top surface of the plasmon generator; a second portion opposed to the first rear end face portion; a third portion opposed to the second rear end face portion; a fourth portion opposed to at least part of the third side surface; and a fifth portion opposed to at least part of the fourth side surface. The outer surface of the heat sink may further include a sixth portion opposed to at least part of the first side surface, and a seventh portion opposed to at least part of the second side surface.

The thermally-assisted magnetic recording head of the present invention further includes: a shield formed of a magnetic material and having an end face located in the medium facing surface; and a return path section formed of a magnetic material, connecting the main pole and the shield to each other and passing a magnetic flux corresponding to the magnetic field produced by the coil.

The near-field light generating surface may be located between the front end face of the main pole and at least part of the end face of the shield. The return path section may include a first yoke portion, a second yoke portion, a first columnar portion, a second columnar portion, and a third columnar portion. The first yoke portion, the second yoke portion and the first columnar portion are located on the same side in the direction of travel of the recording medium relative to the core. The first columnar portion is located away from the medium facing surface and has a first end and a second end opposite to each other in the direction of travel of the recording medium. The second and third columnar portions are located closer to the medium facing surface than is the first columnar portion. The first yoke portion connects the main pole to the first end of the first columnar portion. The second columnar portion and the third columnar portion are located on opposite sides of the plasmon generator in the track width direction, and are connected to the shield. The second yoke portion is connected to the second end of the first columnar portion, and is connected to the shield via the second and third columnar portions. The coil is wound around the first columnar portion.

The end face of the shield may include a first side shield end face and a second side shield end face located on opposite sides of the first end face portion of the front end face of the main pole in the track width direction.

A first and a second manufacturing method for the thermally-assisted magnetic recording head of the present invention each include the steps of forming the waveguide, forming the plasmon generator and the main pole, and forming the coil.

In the first manufacturing method, the main pole is formed to include a first layer, and a second layer stacked on the first layer. The first layer has the first end face portion, and the second layer has the second end face portion. In the first manufacturing method, the step of forming the plasmon generator and the main pole includes the steps of forming an initial plasmon generator; forming a first magnetic layer for use to form the first layer of the main pole; etching the initial plasmon generator into the plasmon generator by using the first magnetic layer as an etching mask; and forming a second magnetic layer on the first magnetic layer, the second magnetic layer being intended for use to form the second layer of the main pole.

In the second manufacturing method, the step of forming the plasmon generator and the main pole includes the steps of forming an initial plasmon generator; forming an etching mask for use to pattern the initial plasmon generator; etching the initial plasmon generator into the plasmon generator by using the etching mask; forming a surrounding layer of a dielectric material around the plasmon generator and the etching mask; removing the etching mask so that a recess is formed by the plasmon generator and the surrounding layer; and forming a magnetic layer such that a portion thereof is received in the recess, the magnetic layer being intended for use to form the main pole.

According to the present invention, the front end face of the main pole includes the first end face portion and the second end face portion, the second end face portion being greater than the first end face portion in width in the track width direction. The track width depends on the width of the first end face portion of the front end face of the main pole. The present invention thus make it possible to achieve a small track width and allows for production of a write magnetic field of sufficient magnitude from the main pole.

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. 1toFIG. 8to describe the configuration of a thermally-assisted magnetic recording head according to a first embodiment of the invention.FIG. 1is a perspective view showing the main part of the thermally-assisted magnetic recording head.FIG. 2is an enlarged perspective view of a part ofFIG. 1.FIG. 3is a front view showing the main part of the thermally-assisted magnetic recording head.FIG. 4is a cross-sectional view showing the main part of the thermally-assisted magnetic recording head.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.FIG. 7is a plan view showing a first layer of a coil of the present embodiment.FIG. 8is a plan view showing a second layer of the coil of the present embodiment.

The thermally-assisted magnetic recording head according to the present embodiment is intended for use in perpendicular magnetic recording, and is in the form of a slider configured 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 surface80configured to face a recording medium90. 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 medium90, i.e., the track width direction. The Y direction is a direction perpendicular to the medium facing surface80. The Z direction is the direction of travel of the recording medium90as 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 surface80. 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, a nonmagnetic layer10formed of a nonmagnetic material and disposed on the middle shield layer9, and a write head unit disposed on the nonmagnetic layer10. The middle shield layer9has the function of shielding the MR element5from magnetic fields generated in the write head unit. The insulating layer8and the nonmagnetic layer10are formed of alumina, for example.

The write head unit includes a coil50and a main pole30. The coil50produces a magnetic field corresponding to data to be written on the recording medium90. As shown inFIG. 1,FIG. 3andFIG. 4, the main pole30has a front end face30alocated in the medium facing surface80. The main pole30is configured to pass a magnetic flux corresponding to the magnetic field produced by the coil50, and to produce from the front end face30aa write magnetic field for writing data on the recording medium. The coil50is formed of a conductive material such as copper.

The write head unit further includes a shield12formed of a magnetic material, and a return path section R formed of a magnetic material. As shown inFIG. 5, the shield12has an end face12alocated in the medium facing surface80. The return path section R connects the main pole30and the shield12to each other, and passes a magnetic flux corresponding to the magnetic field produced by the coil50.

The return path section R includes a return pole layer11, two coupling sections13A and13B, coupling layers37,38and39, and a first yoke portion40. The return pole layer11lies on the nonmagnetic layer10. The return pole layer11has an end face located in the medium facing surface80. The write head unit further includes a non-illustrated insulating layer provided around the return pole layer11. The non-illustrated insulating layer is formed of alumina, for example.

The shield12is located on a first portion of the top surface of the return pole layer11, the first portion being near the medium facing surface80. The two coupling sections13A and13B are located on two second portions of the top surface of the return pole layer11, the two second portions being located away from the medium facing surface80. Each of the coupling sections13A and13B includes a first layer lying on the return pole layer11, and a second and a third layer stacked in this order on the first layer. The first layer of the coupling section13A and the first layer of the coupling section13B are arranged to be adjacent in the track width direction (the X direction).

The write head unit further includes an insulating layer14lying on the non-illustrated insulating layer and a portion of the top surface of the return pole layer11other than the first and second portions. The first layers of the coupling sections13A and13B are embedded in the insulating layer14. The insulating layer14is formed of alumina, for example.

The write head unit further includes a waveguide including a core16and a cladding, the core16allowing light to propagate therethrough, the cladding being provided around the core16. As shown inFIG. 1andFIG. 3toFIG. 5in particular, the core16has a front end face16afacing toward the medium facing surface80, an evanescent light generating surface16bwhich is a top surface, a bottom surface16c, and two side surfaces16dand16e. The front end face16amay be located in the medium facing surface80or at a distance from the medium facing surface80.FIG. 1andFIG. 3toFIG. 6show an example in which the front end face16ais located in the medium facing surface80.

The cladding includes cladding layers15,17and18. The cladding layer15lies on the shield12and the insulating layer14. The core16lies on the cladding layer15. The cladding layer17lies on the cladding layer15and surrounds the core16. The cladding layer18is disposed over the evanescent light generating surface16bof the core16and the top surface of the cladding layer17.

The core16is formed of a dielectric material that transmits laser light to be used for generating near-field light. The laser light emitted from a non-illustrated laser diode enters the core16and propagates through the core16. The cladding layers15,17and18are each formed of a dielectric material that has a refractive index lower than that of the core16. For example, the core16may be formed of tantalum oxide such as Ta2O5or silicon oxynitride (SiON), whereas the cladding layers15,17and18may be formed of silicon oxide (SiO2) or alumina.

The second layers of the coupling sections13A and13B are embedded in the cladding layers15and17. The second layer of the coupling section13A and the second layer of the coupling section13B are located on opposite sides of the core16in the track width direction (the X direction) and spaced from the core16.

The write head unit further includes a plasmon generator20disposed above the cladding layer18in the vicinity of the medium facing surface80, and an adhesion layer19interposed between the cladding layer18and the plasmon generator20.FIG. 5andFIG. 6omit the illustration of the adhesion layer19. The plasmon generator20is intended for use to excite surface plasmons on the principle to be described later. The adhesion layer19is provided to prevent the plasmon generator20from peeling away from the cladding layer18. The adhesion layer19may be formed of one of Zr, ZrN, Ru, Pt, Pd, Ti, Ta, Ni, W, Cr, NiCr, NiFe, Co, Cu, TiW, TiN, Mo, Hf, and Rh, for example. The adhesion layer19may have a thickness of 0.3 to 1 nm, for example. The adhesion layer19is not an essential component of the thermally-assisted magnetic recording head, and can be dispensed with. The plasmon generator20will be described in detail later.

The write head unit further includes a dielectric layer24lying on a portion of the plasmon generator20in the vicinity of the medium facing surface80, and a nonmagnetic metal film25lying on another portion of the plasmon generator20and on the dielectric layer24.FIG. 5andFIG. 6omit the illustration of the dielectric layer24and the nonmagnetic metal film25. The dielectric layer24is formed of the same material as the cladding layers15,17and18, for example. The nonmagnetic metal film25has the function of preventing the material of the plasmon generator20from diffusing into the main pole30, and thereby preventing deterioration of the magnetic properties of the main pole30. The nonmagnetic metal film25is formed of Ru, Ta or Ti, for example.

In the present embodiment, the main pole30includes a first layer31, and a second layer32stacked on the first layer31. The first layer31lies on the nonmagnetic metal film25. The plasmon generator20lies between the core16and the first layer31. The write head unit further includes a surrounding layer27and a dielectric film26. The surrounding layer27is formed of a dielectric material and provided around the plasmon generator20, the dielectric layer24, the nonmagnetic metal film25and the first layer31. The dielectric film26is interposed between the surrounding layer27and each of the plasmon generator20, the dielectric layer24, the nonmagnetic metal film25and the first layer31.FIG. 6omits the illustration of the dielectric film26. The dielectric film26and the surrounding layer27are formed of the same material as the cladding layers15,17and18, for example.

The second layer32lies on the first layer31and the surrounding layer27. The write head unit further includes a heat sink34and a nonmagnetic metal film33. The heat sink34is disposed above the plasmon generator20and the surrounding layer27and surrounds a portion of the first layer31and the second layer32. The nonmagnetic metal film33is interposed between the heat sink34and each of the plasmon generator20, the main pole30and the surrounding layer27.FIG. 5andFIG. 6omit the illustration of the nonmagnetic metal film33. The heat sink34has the function of dissipating heat generated at the plasmon generator20and heat transferred from the plasmon generator20to the main pole30outward from the plasmon generator20and the main pole30. The heat sink34is formed of Au or Cu, for example. The nonmagnetic metal film33has the function of preventing the materials of the plasmon generator20and the heat sink34from diffusing into the main pole30, and thereby preventing deterioration of the magnetic properties of the main pole30. The nonmagnetic metal film33is formed of the same material as the nonmagnetic metal film25, for example.

The write head unit further includes a dielectric layer35provided around the heat sink34. The top surfaces of the second layer32, the heat sink34and the dielectric layer35are even with each other. The dielectric layer35is formed of the same material as the cladding layers15,17and18, for example.

The third layers of the coupling sections13A and13B are embedded in the cladding layer18, the surrounding layer27and the dielectric layer35. The coupling layer37lies on the third layers of the coupling sections13A and13B and the dielectric layer35.

The first yoke portion40includes a first layer41, a second layer42, a third layer43and a fourth layer44. A portion of the first layer41lies on the main pole30, and another portion of the first layer41lies above the heat sink34. The first layer41has an end face located in the medium facing surface80. The first layer41may include a narrow portion and a wide portion as shown inFIG. 7, the narrow portion having the aforementioned end face of the first layer41and an end opposite thereto, the wide portion being 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 width of the narrow portion in the track width direction is substantially constant regardless of distance from the medium facing surface80. The width of the wide portion in the track width direction is equal to that of the narrow portion at the boundary between the narrow portion and the wide portion, and gradually increases with increasing distance from the medium facing surface80, then becoming constant.

The write head unit further includes a nonmagnetic metal film36interposed between the heat sink34and the first layer41, and a dielectric layer45provided around the first layer41and the coupling layer37. The nonmagnetic metal film36is shown inFIG. 23AandFIG. 23Bto be described later. The nonmagnetic metal film36has the function of preventing the material of the heat sink34from diffusing into the first layer41. The nonmagnetic metal film36is formed of the same material as the nonmagnetic metal film25, for example. The dielectric layer45is formed of the same material as the cladding layers15,17and18, for example.

The second layer42of the first yoke portion40lies on the first layer41. The second layer42has an end face facing toward the medium facing surface80and located at a distance from the medium facing surface80. The coupling layer38lies on the coupling layer37.

The coil50includes a first layer51and a second layer52. The write head unit further includes an insulating film53, an insulating layer54and an insulating layer55. The insulating film53is interposed between the first layer51of the coil50and each of the second layer42of the first yoke portion40, the coupling layer38and the dielectric layer45. The insulating layer54is disposed around the first layer51and the second layer42and in the space between adjacent turns of the first layer51. The insulating layer55lies on the first layer51, the insulating film53and the insulating layer54. The insulating film53and the insulating layers54and55are formed of alumina, for example.

The third layer43of the first yoke portion40lies on the second layer42. The third layer43has an end face facing toward the medium facing surface80and located at a distance from the medium facing surface80. The coupling layer39lies on the coupling layer38.

The write head unit further includes an insulating film56, an insulating layer57and an insulating layer58. The insulating film56is interposed between the second layer52of the coil50and each of the third layer43of the first yoke portion40, the coupling layer39and the insulating layer55. The insulating layer57is disposed around the second layer52and the third layer43and in the space between adjacent turns of the second layer52. The insulating layer58lies on the second layer52, the insulating film56and the insulating layer57. The insulating film56and the insulating layers57and58are formed of alumina, for example.

The fourth layer44of the first yoke portion40lies on the third layer43, the coupling layer39and the insulating layer58. The fourth layer44has an end face facing toward the medium facing surface80and located at a distance from the medium facing surface80. The write head unit further includes an insulating layer59disposed around the fourth layer44. The insulating layer59is formed of alumina, for example.

The thermally-assisted magnetic recording head further includes a protective layer60disposed to cover the write head unit. The protective layer60is formed of alumina, for example.

As has been described, the thermally-assisted magnetic recording head according to the present embodiment includes the medium facing surface80, 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 trailing side, i.e., the front side in the direction of travel of the recording medium90(the Z direction), relative to the read head unit.

The write head unit includes the coil50, the main pole30, the waveguide, the plasmon generator20, the shield12, the return path section R, the dielectric layer24, and the heat sink34. The waveguide includes the core16and the cladding. The cladding includes the cladding layers15,17and18. The return path section R includes the return pole layer11, the two coupling sections13A and13B, the coupling layers37to39, and the first yoke portion40. The dielectric layer24is provided between the main pole30and the plasmon generator20.

The main pole30has the front end face30alocated in the medium facing surface80. The shield12has the end face12alocated in the medium facing surface80. The front end face30aand the end face12aare at locations different from each other in the direction of travel of the recording medium90(the Z direction). In the present embodiment, in particular, the end face12ais located on the leading side, i.e., the rear side in the direction of travel of the recording medium90, relative to the front end face30a.

The main pole30is located on the front side in the direction of travel of the recording medium90relative to the core16. The core16has the front end face16alocated in the medium facing surface80. The front end face16alies between the front end face30aof the main pole30and at least part of the end face12aof the shield12.

The shield12captures a disturbance magnetic field applied to the thermally-assisted magnetic recording head from the outside thereof. This makes it possible to prevent the disturbance magnetic field from being intensively captured into the main pole30and thereby causing erroneous writing on the recording medium90. The shield12also has the function of capturing a magnetic flux that is produced from the front end face30aof the main pole30and spreads in directions other than the direction perpendicular to the plane of the recording medium90, and thereby preventing the magnetic flux from reaching the recording medium90. It is thereby possible to increase the gradient of intensity of the write magnetic field. The shield12and the return path section R also have the function of allowing a magnetic flux that has been produced from the front end face30aof the main pole30and has magnetized a portion of the recording medium90to flow back to the main pole30.

The shape and location of the coil50will now be described in detail with reference toFIG. 7andFIG. 8. As shown inFIG. 7, the first layer51of the coil50is wound approximately three times around the coupling layer38. The first layer51includes a portion extending to pass between the second layer42of the first yoke portion40and the coupling layer38. The first layer51has a coil connection51E electrically connected to the second layer52of the coil50.

As shown inFIG. 8, the second layer52is wound approximately three times around the coupling layer39. The second layer52includes a portion extending to pass between the third layer43of the first yoke portion40and the coupling layer39. The second layer52has a coil connection52S electrically connected to the coil connection51E of the first layer51. The coil connection52S penetrates the insulating layer55and the insulating film56(seeFIG. 5) and is electrically connected to the coil connection51E. In the example shown inFIG. 7andFIG. 8, the first layer51and the second layer52are connected in series.

The plasmon generator20will now be described in detail with reference toFIG. 1toFIG. 4. The plasmon generator20has a near-field light generating surface20alocated in the medium facing surface80, a plasmon exciting section20bwhich is a bottom surface, a top surface20c, a rear end face20dopposite to the near-field light generating surface20a, and two side surfaces20eand20f. The plasmon exciting section20bis located at a predetermined distance from the evanescent light generating surface16bof the core16and faces the evanescent light generating surface16b. The cladding layer18is interposed between the evanescent light generating surface16band the plasmon exciting section20b. For example, the plasmon generator20is rectangular in cross section parallel to the medium facing surface80. The near-field light generating surface20ais located between the front end face30aof the main pole30and the front end face16aof the core16. The near-field light generating surface20agenerates near-field light on the principle to be described later.

As shown inFIG. 2andFIG. 4, the plasmon generator20includes a multilayer film section21and a metal section22. The multilayer film section21has a front end face located in the medium facing surface80, a rear end opposite to the front end face, a bottom surface, a top surface, and two side surfaces. The front end face of the multilayer film section21also serves as the near-field light generating surface20aof the plasmon generator20. The dielectric layer24lies on the top surface of the multilayer film section21.

The metal section22is located on a side of the multilayer film section21farther from the near-field light generating surface20a. The metal section22has a front end connected to the rear end of the multilayer film section21, a rear end face opposite to the front end, a bottom surface, a top surface, and two side surfaces. The top surface of the metal section22includes an inclined portion and a flat portion, the inclined portion being located closer to the multilayer film section21than is the flat portion. The inclined portion has a first end closest to the multilayer film section21, and a second end opposite thereto. The inclined portion is inclined such that its second end is located on the front side in the direction of travel of the recording medium90relative to its first end. The flat portion extends in a direction substantially perpendicular to the medium facing surface80.

The width of the multilayer film section21in the track width direction (X direction) may be constant regardless of distance from the medium facing surface80or decrease with decreasing distance to the medium facing surface80. The width of the metal section22is equal to the width of the multilayer film section21at the boundary between the metal section22and the multilayer film section21, and increases with increasing distance from the multilayer film section21.

The width of the near-field light generating surface20ain the track width direction (the X direction) is defined by the width of the multilayer film section21in the medium facing surface80. The width of the near-field light generating surface20afalls within the range of 5 to 40 nm, for example.

As shown inFIG. 2, the multilayer film section21includes 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 near-field light generating surface20a. Each of the first and second metal layers M1and M2is formed of a metal material. The intermediate layer N1may be formed of either a dielectric material or a metal material that is different from the metal material used to form the first metal layer M1and the metal material used to form the second metal layer M2. Hereinafter, 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 the metal layer material, and the material used to form the intermediate layer N1will be referred to as the intermediate layer material. The intermediate layer material is higher in Vickers hardness than the metal layer material. Where the intermediate layer material is a metal material, the metal layer material is preferably higher in electrical conductivity than the intermediate layer material.

In the example shown inFIG. 2, the intermediate layer N1and the second metal layer M2are stacked in this order on the first metal layer M1. In this example, the multilayer film section21further includes a second intermediate layer N2, a third metal layer M3, and a protective layer N3stacked in this order on the second metal layer M2. Each of the second intermediate layer N2, the third metal layer M3and the protective layer N3has an end located in the near-field light generating surface20a. The metal layer M3is formed of the metal layer material. Each of the intermediate layer N2and the protective layer N3is formed of the intermediate layer material. The protective layer N3has the function of protecting the plasmon generator20and the function of enhancing adhesion of the dielectric layer24to the plasmon generator20.

Examples of the metal layer material include Au, Ag, Al and Cu. Examples of metal materials selectable as the intermediate layer material include Zr, ZrN, Ru, Pt, Pd, Ti, Ta, Ni, W, Cr, NiCr, NiFe, Co, Cu, TiW, TiN, Mo, Hf, and Rh. Examples of dielectric materials selectable as the intermediate layer material include SiO2, alumina, MgO, amorphous SiC, tantalum oxide, SiON, ZrOx, HfOx, and NbOx, where “x” in ZrOx, HfOxand NbOxrepresents any number greater than zero. When the metal layer material is Cu, the intermediate layer material is other than Cu.

As far as the requirement that the intermediate layer material be higher in Vickers hardness than the metal layer material is satisfied, the materials used to form the metal layers M1to M3may all be the same or may be different from each other, or two of them may be the same. Likewise, the materials used to form the intermediate layers N1and N2and the protective layer N3may all be the same or may be different from each other, or two of them may be the same.

The intermediate layers N1and N2and the protective layer N3may be smaller in thickness than the metal layers M1to M3. The thickness of each of the metal layers M1to M3preferably falls within the range of 5 to 25 nm, and the thickness of each of the intermediate layers N1and N2and the protective layer N3preferably falls within the range of 0.5 to 2 nm.

The metal section22is formed of a metal material. The metal material used to form the metal section22may be one of Au, Ag, Al and Cu, for example.

The configuration of the plasmon generator20is not limited to the above-described example. For example, the plasmon generator20may include a single layer portion formed of a single metal material, in place of the multilayer film section21. The single layer portion may have the same shape as the multilayer film section21. The metal material used to form the single layer portion may be one of Au, Ag, Al and Cu, for example. The metal material used to form the single layer portion may be the same as or different from the metal material used to form the metal section22. Further, the plasmon generator20may be composed entirely of a multilayer film formed by alternately stacking metal layers formed of the metal layer material and intermediate layers formed of the intermediate layer material.

The main pole30and the locations of the main pole30and the plasmon generator20relative to each other will now be described in detail with reference toFIG. 1toFIG. 4. As shown inFIG. 1,FIG. 3andFIG. 4, the front end face30aof the main pole30and the near-field light generating surface20aof the plasmon generator20are at locations different from each other in the direction of travel of the recording medium90(the Z direction). In the present embodiment, the front end face30ais located on the trailing side, i.e., the front side in the direction of travel of the recording medium90, relative to the near-field light generating surface20a.

As shown inFIG. 4, the top surface20cof the plasmon generator20includes a first region20c1, and a second region20c2located farther from the medium facing surface80than the first region20c1.

The front end face30aof the main pole30includes a first end face portion31a, and a second end face portion32acontiguous with the first end face portion31a. The second end face portion32ais located farther from the near-field light generating surface20athan is the first end face portion31a, and has a greater width in the track width direction than the first end face portion31a. In the present embodiment, the second end face portion32ais located on the front side in the direction of travel of the recording medium90relative to the first end face portion31a.

As shown inFIG. 3, the first end face portion31ahas a first edge E1and a second edge E2opposite to each other in the track width direction. The near-field light generating surface20ahas a third edge E3and a fourth edge E4opposite to each other in the track width direction. Now, let us assume a first imaginary straight line L1and a second imaginary straight line L2as shown inFIG. 3. The first imaginary straight line L1extends in the Z direction. The second imaginary straight line L2is parallel to the first imaginary straight line L1. The first edge E1and the third edge E3are located on the first imaginary straight line L1. The second edge E2and the fourth edge E4are located on the second imaginary straight line L2.

The distance between the first edge E1and the second edge E2is equal to the width of the first end face portion31ain the track width direction. The distance between the third edge E3and the fourth edge E4is equal to the width of the near-field light generating surface20ain the track width direction. Consequently, the width of the first end face portion31ais equal to the width of the near-field light generating surface20a.

Thus, in the present embodiment, the first end face portion31aand the near-field light generating surface20aare equal in width and are precisely aligned with each other such that the first edge E1and the third edge E3are located on the first imaginary straight line L1and the second edge E2and the fourth edge E4are located on the second imaginary straight line L2.

As previously mentioned, the main pole30includes the first layer31and the second layer32. As shown inFIG. 2toFIG. 4, the first layer31has the first end face portion31amentioned previously, and further has a first rear end face portion31bfarthest from the medium facing surface80, and a first side surface31cand a second side surface31dlocated at opposite ends of the first layer31in the track width direction. As shown inFIG. 1,FIG. 3andFIG. 4, the second layer32has the second end face portion32amentioned previously, and further has a second rear end face portion32bfarthest from the medium facing surface80, and a third side surface32cand a fourth side surface32dlocated at opposite ends of the second layer32in the track width direction. In the present embodiment, as shown inFIG. 4, the first rear end face portion31band the second rear end face portion32bare located at the same distance from the medium facing surface80.

As shown inFIG. 1andFIG. 2, the first layer31may include a first narrow portion and a first wide portion, the first narrow portion having the first end face portion31aand an end opposite thereto, the first wide portion being connected to the end of the first narrow portion. The first wide portion is greater than the first narrow portion in width in the track width direction (the X direction). The width of the first narrow portion in the track width direction is substantially constant regardless of distance from the medium facing surface80. The width of the first wide portion in the track width direction is equal to that of the first narrow portion at the boundary between the first narrow portion and the first wide portion, and increases with increasing distance from the medium facing surface80. The first layer31need not necessarily include the first narrow portion. In such a case, the first wide portion has the first end face portion31a.

As shown inFIG. 1, the second layer32may include a second narrow portion and a second wide portion, the second narrow portion having the second end face portion32aand an end opposite thereto, the second wide portion being connected to the end of the second narrow portion. The second wide portion is greater than the second narrow portion in width in the track width direction (the X direction). The width of the second narrow portion in the track width direction is substantially constant regardless of distance from the medium facing surface80. The width of the second wide portion in the track width direction is equal to that of the second narrow portion at the boundary between the second narrow portion and the second wide portion, and gradually increases with increasing distance from the medium facing surface80, then becoming constant. The second layer32need not necessarily include the second narrow portion. In such a case, the second wide portion has the second end face portion32a.

As shown inFIG. 2andFIG. 4, the first layer31further has a top surface31eand a bottom surface31f. As shown inFIG. 4, the bottom surface31fis opposed to the first region20c1of the top surface20cof the plasmon generator20. The top surface31eincludes a first flat portion31e1, an inclined portion31e2and a second flat portion31e3arranged in this order, the first flat portion31e1being closest to the medium facing surface80. The inclined portion31e2has a first end connected to the first flat portion31e1and a second end connected to the second flat portion31e3. The inclined portion31e2is inclined such that its second end is located on the front side in the direction of travel of the recording medium90relative to its first end. The first and second flat portions31e1and31e3extend in a direction substantially perpendicular to the medium facing surface80.

The distance between the bottom surface31fof the first layer31and the evanescent light generating surface16bof the core16increases with increasing distance from the medium facing surface80. According to the present embodiment, this configuration makes it possible to prevent the light propagating through the core16from being absorbed in part by the main pole30and to prevent the surface plasmons excited on the plasmon exciting section20bfrom being absorbed in part by the main pole30.

The heat sink34will now be described with reference toFIG. 3and FIG.4. The heat sink34has an outer surface including a first to a fifth portion opposed to the plasmon generator20and the first layer31and the second layer32of the main pole30, as described below. The first portion is opposed to the second region20c2of the top surface20cof the plasmon generator20. The second portion is opposed to the first rear end face portion31bof the first layer31. The third portion is opposed to the second rear end face portion32bof the second layer32. The fourth portion is opposed to at least part of the third side surface32cof the second layer32. The fifth portion is opposed to at least part of the fourth side surface32dof the second layer32.FIG. 3shows an example in which the fourth portion is opposed to the entire third side surface32cwhile the fifth portion is opposed to the entire fourth side surface32d. The nonmagnetic metal film33is interposed between the first to the fifth portion of the outer surface of the heat sink34and the plasmon generator20, the first layer31and the second layer32.

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 core16. As shown inFIG. 5, the laser light150propagates through the core16toward the medium facing surface80, and reaches the vicinity of the plasmon generator20. The evanescent light generating surface16bof the core16generates evanescent light based on the laser light150propagating through the core16. More specifically, the laser light150is totally reflected at the evanescent light generating surface16b, and the evanescent light generating surface16bthereby generates evanescent light that permeates into the cladding layer18. In the plasmon generator20, surface plasmons are excited on the plasmon exciting section20bthrough coupling with the aforementioned evanescent light. The surface plasmons propagate to the near-field light generating surface20a, and the near-field light generating surface20agenerates near-field light based on the surface plasmons.

The near-field light generated from the near-field light generating surface20ais projected toward the recording medium90, reaches the surface of the recording medium90and heats a part of the magnetic recording layer of the recording medium90. 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 pole30for data writing.

The specific functions and effects of the thermally-assisted magnetic recording head according to the present embodiment will now be described. On the recording medium90, a spot of near-field light is formed and a thermal spot is generated by the spot of near-field light. The thermal spot size on the recording medium90is larger than the light spot size on the recording medium90and than the width of the near-field light generating surface20a. On the other hand, of the first and second end face portions31aand32aof the front end face30aof the main pole30, the first end face portion31ais located closer to the near-field light generating surface20athan is the second end face portion32a. The first end face portion31ahas a width equal to that of the near-field light generating surface20a. In general, the spread of the magnetic field generated from the first end face portion31ais smaller than the spread of heat on the recording medium90. Thus, in the present embodiment, track width depends on the width of the first end face portion31a. Further, because the spread of the magnetic field generated from the first end face portion31ais smaller than the spread of heat on the recording medium90as mentioned above, the present embodiment is able to achieve a smaller track width and accordingly, a higher recording density when compared with the approach of reducing the light spot size.

The front end face30aof the main pole30includes the second end face portion32awhich has a greater width in the track width direction than the first end face portion31a. According to the present embodiment, this configuration makes it possible for the main pole30to pass a larger amount of magnetic flux than in the case where the front end face30aconsists only of the first end face portion31a.

Consequently, the present embodiment makes it possible to provide a reduced track width and produce a write magnetic field of sufficient magnitude from the main pole30.

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 a plurality pre-head portions arranged in rows, 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 surface80for each of the plurality of pre-head portions (this step will be referred to as the step of forming the medium facing surface80). 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 be described in more detail below with attention focused on a single thermally-assisted magnetic recording head. The method of manufacturing the thermally-assisted magnetic recording head starts with forming the insulating layer2, the bottom shield layer3, and the bottom shield gap film4in this order on the substrate1. Then, 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.

The return pole layer11is then formed on the nonmagnetic layer10. Next, a non-illustrated insulating layer is formed to cover the return pole layer11. The non-illustrated insulating layer is then polished by, for example, chemical mechanical polishing (hereinafter referred to as CMP), until the return pole layer11is exposed. Next, the shield12and the first layers of the coupling sections13A and13B are formed on the return pole layer11. Then, the insulating layer14is formed over the entire top surface of the stack. The insulating layer14is then polished by, for example, CMP, until the shield12and the first layers of the coupling sections13A and13B are exposed.

Next, the cladding layer15is formed over the entire top surface of the stack. The cladding layer15is then selectively etched to form therein two openings for exposing the top surfaces of the first layers of the coupling sections13A and13B. Then, the second layers of the coupling sections13A and13B are formed on the first layers of the coupling sections13A and13B, respectively. The core16is then formed on the cladding layer15. The cladding layer17is then formed over the entire top surface of the stack. The cladding layer17is then polished by, for example, CMP, until the core16and the second layers of the coupling sections13A and13B are exposed. Then, the cladding layer18is formed over the entire top surface of the stack.

Reference is now made toFIG. 9AthroughFIG. 23Bto describe steps to be performed after the formation of the cladding layer18up to the formation of the coupling layer37, the first layer41of the first yoke portion40and the dielectric layer45.FIG. 9AthroughFIG. 23Beach show a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head.FIG. 9AthroughFIG. 23Bomit the illustration of portions located below the cladding layer18. FIG. nA (n is an integer between9and23inclusive) shows a cross section that intersects the front end face30aof the main pole30and that is perpendicular to the medium facing surface80and to the top surface1aof the substrate1. FIG. nB shows a cross section of the stack taken at the location at which the medium facing surface80is to be formed.

FIG. 9AandFIG. 9Bshow a step that follows the formation of the cladding layer18. In this step, first, the adhesion layer19is formed on the cladding layer18by sputtering, for example. Then, a plurality of films that will later become the layers constituting the multilayer film section21of the plasmon generator20are formed in succession on the adhesion layer19by sputtering, for example. An initial multilayer film section21P constituted by these plurality of films is thereby formed.

Next, the dielectric layer24is formed on the initial multilayer film section21P. A photoresist mask81for defining the location of the rear end of the multilayer film section21is then formed on the dielectric layer24. The photoresist mask81is formed by patterning a photoresist layer by photolithography. Other photoresist masks to be used in later steps will be formed in the same manner as the photoresist mask81.

FIG. 10AandFIG. 10Bshow the next step. In this step, first, the initial multilayer film section21P is etched by, for example, reactive ion etching (hereinafter referred to as RIE) or ion beam etching (hereinafter referred to as IBE), using the photoresist mask81. The photoresist mask81is then removed.

FIG. 11AandFIG. 11Bshow the next step. In this step, an initial metal section22P, which will later become the metal section22of the plasmon generator20, is formed on the adhesion layer19and the initial multilayer film section21P by sputtering, for example. The initial metal section22P may be formed while heating the stack to a temperature in the range of 300° C. to 400° C. This makes it possible to prevent the metal section22of the plasmon generator20from being deformed by heat generated by the plasmon generator20during use of the thermally-assisted magnetic recording head.

FIG. 12AandFIG. 12Bshow the next step. In this step, first, a photoresist mask82is formed on the initial metal section22P at a location apart from the location at which the medium facing surface80is to be formed. The photoresist mask82covers only part of the portion of the initial metal section22P lying on the adhesion layer19. Next, the initial metal section22P is taper-etched by, for example, RIE or IBE, using the photoresist mask82so as to provide the initial metal section22P with an inclined surface. This etching continues until the dielectric layer24is exposed. The inclined surface includes a portion that will later become the inclined portion of the top surface of the metal section22. The photoresist mask82is then removed. An initial plasmon generator constituted by the initial multilayer film section21P and the initial metal section22P is formed through the series of steps shown inFIG. 9AtoFIG. 12B.

FIG. 13AandFIG. 13Bshow the next step. In this step, first, the nonmagnetic metal film25is formed on the initial metal section22P and the dielectric layer24by sputtering, for example. Next, a first magnetic layer31P for use to form the first layer31of the main pole30is formed on the nonmagnetic metal film25by sputtering, for example. The first magnetic layer31P is formed such that its top surface is higher in level than the second flat portion31e3(seeFIG. 4) of the top surface31eof the first layer31to be formed later. The first magnetic layer31P is larger in planar shape (the shape as viewed from above) than the first layer31.

FIG. 14AandFIG. 14Bshow the next step. In this step, a first mask layer83and a second mask layer84are formed in this order on the first magnetic layer31P. The first mask layer83is formed of alumina, for example. The second mask layer84is formed of carbon, for example. The first and second mask layers83and84are shaped to correspond to the planar shape of the plasmon generator20.

FIG. 15AandFIG. 15Bshow the next step. In this step, the first magnetic layer31P and the initial plasmon generator are etched by, for example, RIE or IBE in the following manner and thereby patterned. First, the first magnetic layer31P is etched using the first and second mask layers83and84as an etching mask, and subsequently, the nonmagnetic metal film25, the dielectric layer24, the initial plasmon generator and the adhesion layer19are etched using the first and second mask layers83and84and the etched first magnetic layer31P as an etching mask. The etched first magnetic layer31P has a side surface including the first side surface31cof the first layer31and a side surface including the second side surface31dof the first layer31. The etching makes the initial multilayer film section21P and the initial metal section22P into the multilayer film section21and the metal section22, respectively. In this way, the etching makes the initial plasmon generator into the plasmon generator20.

FIG. 16AandFIG. 16Bshow the next step. In this step, first, the dielectric film26is formed to cover the adhesion layer19, the plasmon generator20, the dielectric layer24, the nonmagnetic metal film25, the first magnetic layer31P, the first mask layer83and the second mask layer84. Then, the surrounding layer27is formed over the entire top surface of the stack.

FIG. 17AandFIG. 17Bshow the next step. In this step, the first magnetic layer31P, the dielectric film26, the surrounding layer27, the first mask layer83, and the second mask layer84are polished by, for example, CMP, until the level of the second flat portion31e3of the top surface31eof the first layer31to be formed later is reached.

FIG. 18AandFIG. 18Bshow the next step. In this step, first, a photoresist mask85is formed on the first magnetic layer31P at a location apart from the location at which the medium facing surface80is to be formed. Then, respective portions of the dielectric film26, the surrounding layer27and the first magnetic layer31P are etched by, for example, RIE or IBE using the photoresist mask85so as to provide the first magnetic layer31P with the first flat portion31e1and the inclined portion31e2of the top surface31eof the first layer31. The photoresist mask85is then removed.

FIG. 19AandFIG. 19Bshow the next step. In this step, first, the cladding layer18and the surrounding layer27are selectively etched to form therein two openings for exposing the top surfaces of the second layers of the coupling sections13A and13B (seeFIG. 5). Then, the third layers of the coupling sections13A and13B are formed on the second layers of the coupling sections13A and13B, respectively. Further, a second magnetic layer32P for use to form the second layer32of the main pole30is formed on the surrounding layer27and the first magnetic layer31P. The third layers of the coupling sections13A and13B and the second magnetic layer32P are formed such that their top surfaces are higher in level than the top surface of the second layer32to be formed later. The second magnetic layer32P has a planar shape corresponding to that of the second layer32. The second magnetic layer32P has a rear end face including the second rear end face portion32bof the second layer32, a side surface including the third side surface32cof the second layer32, and a side surface including the fourth side surface32dof the second layer32.

FIG. 20AandFIG. 20Bshow the next step. In this step, first, the first magnetic layer31P is etched by, for example, IBE, using the second magnetic layer32P as an etching mask. This etching provides the first magnetic layer31P with the first rear end face portion31band thereby makes the first magnetic layer31P into the first layer31. Next, the nonmagnetic metal film33is formed to cover the metal section22of the plasmon generator20, the surrounding layer27, the first layer31and the second magnetic layer32P.

FIG. 21AandFIG. 21Bshow the next step. In this step, a nonmagnetic metal layer34P for use to form the heat sink34is formed on the nonmagnetic metal film33so as to cover the metal section22of the plasmon generator20, the surrounding layer27and the second magnetic layer32P.

FIG. 22AandFIG. 22Bshow the next step. In this step, first, the dielectric layer35(seeFIG. 5andFIG. 6) is formed over the entire top surface of the stack. Then, the third layers of the coupling sections13A and13B, the second magnetic layer32P, the nonmagnetic metal film33, the nonmagnetic metal layer34P and the dielectric layer35are polished by, for example, CMP, until the level of the top surface of the second layer32is reached. This polishing makes the second magnetic layer32P into the second layer32, and thereby completes the main pole30. Further, this polishing makes the nonmagnetic metal layer34P into the heat sink34.

FIG. 23AandFIG. 23Bshow the next step. In this step, first, the nonmagnetic metal film36is formed on the heat sink34. Then, the first layer41of the first yoke portion40is formed on the second layer32, the dielectric layer35and the nonmagnetic metal film36, and the coupling layer37(seeFIG. 5) is formed on the third layers of the coupling sections13A and13B and the dielectric layer35. Next, the dielectric layer45(seeFIG. 5andFIG. 6) is formed over the entire top surface of the stack. The dielectric layer45is then polished by, for example, CMP, until the first layer41and the coupling layer37are exposed.

Now, steps to follow the step shown inFIG. 23AandFIG. 23Bwill be described with reference toFIG. 5andFIG. 6. First, the second layer42of the first yoke portion40is formed on the first layer41, and the coupling layer38is formed on the coupling layer37. Then, the insulating film53is formed over the entire top surface of the stack. The first layer51of the coil50is then formed on the insulating film53. Next, the insulating layer54is formed over the entire top surface of the stack. The insulating film53and the insulating layer54are then polished by, for example, CMP, until the second layer42, the coupling layer38and the first layer51are exposed.

Next, the insulating layer55is formed on the first layer51of the coil50and the insulating layer54. Then, the third layer43of the first yoke portion40is formed on the second layer42, and the coupling layer39is formed on the coupling layer38. Next, the insulating film56is formed over the entire top surface of the stack. The insulating layer55and the insulating film56are then selectively etched to form therein openings for exposing the coil connection51E (seeFIG. 7) of the first layer51of the coil50. Then, the second layer52of the coil50is formed on the insulating film56and the coil connection51E. Next, the insulating layer57is formed over the entire top surface of the stack. The insulating film56and the insulating layer57are then polished by, for example, CMP, until the third layer43, the coupling layer39and the second layer52are exposed.

Next, the insulating layer58is formed on the second layer52of the coil50and the insulating layer57. The fourth layer44of the first yoke portion40is then formed on the third layer43of the first yoke portion40, the coupling layer39and the insulating layer58. Next, the insulating layer59is formed over the entire top surface of the stack. The insulating layer59is then polished by, for example, CMP, until the fourth layer44is exposed. Then, the protective layer60is formed to cover the fourth layer44and the insulating layer59. Wiring, terminals, and other components are then formed on the top surface of the protective layer60. When the substructure is completed thus, the step of forming the medium facing surface80is performed. A protective film for covering the medium facing surface80may be formed thereafter. Being provided with the medium facing surface80, each pre-head portion becomes a thermally-assisted magnetic recording head.

The step of forming the medium facing surface80includes the step of polishing the surface of each pre-head portion that has resulted from 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 surface80may be polished in different amounts due to differences between materials used for those layers, and this may cause irregularities on the medium facing surface80.

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 surface80may include the step of etching the polished surface slightly by, for example, IBE, after the polishing step.

The method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment forms the plasmon generator20by etching the initial plasmon generator constituted by the initial multilayer film section21P and the initial metal section22P, using the first magnetic layer31P for use to form the first layer31of the main pole30as an etching mask. According to the present embodiment, this makes it possible to form the plasmon generator20and the main pole30in a self-aligned manner so that the first and second edges E1and E2of the first end face portion31aof the front end face30aof the main pole30and the third and fourth edges E3and E4of the near-field light generating surface20aof the plasmon generator20are brought into the previously described positional relationship with each other.

Second Embodiment

A thermally-assisted magnetic recording head according to a second embodiment of the invention will now be described with reference toFIG. 24andFIG. 25.FIG. 24is a front view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.FIG. 25is a cross-sectional view showing the main part of the thermally-assisted magnetic recording head according to the present embodiment.

The thermally-assisted magnetic recording head according to the present embodiment is configured differently than the first embodiment as described below. The thermally-assisted magnetic recording head according to the present embodiment includes a heat sink46provided around the plasmon generator20and the first layer31of the main pole30. The heat sink46has the function of dissipating heat generated at the plasmon generator20and heat transferred from the plasmon generator20to the first layer31outward from the plasmon generator20and the first layer31. For example, the heat sink46is formed of the same material as the heat sink34described in the first embodiment section. The heat sinks34and46each correspond to the heat sink of the present invention.

In the present embodiment, the top surface of the surrounding layer27is at a level different from that in the first embodiment. As shown inFIG. 24, in the present embodiment the top surface of the surrounding layer27is closer to the top surface1a(seeFIG. 5andFIG. 6) of the substrate1than in the first embodiment. The heat sink46lies on the surrounding layer27.

The heat sink46has an outer surface including a sixth portion and a seventh portion as described below. The sixth portion is opposed to at least part of the first side surface31cof the first layer31. The seventh portion is opposed to at least part of the second side surface31dof the first layer31.FIG. 24shows an example in which the sixth portion is opposed to the entire first side surface31cwhile the seventh portion is opposed to the entire second side surface31d. In the present embodiment, the sixth portion is also opposed to part of the side surface20e(seeFIG. 2) of the plasmon generator20while the seventh portion is also opposed to part of the side surface20f(seeFIG. 2) of the plasmon generator20. The dielectric film26is interposed between the sixth and the seventh portion of the outer surface of the heat sink34and each of the plasmon generator20and the first layer31.

A portion of the heat sink34lies above the heat sink46. Another portion of the heat sink34lies above the plasmon generator20and the surrounding layer27. The nonmagnetic metal film33is interposed between the heat sink34and each of the heat sink46, the plasmon generator20and the surrounding layer27.

The thermally-assisted magnetic recording head according to the present embodiment further includes a nonmagnetic metal film47interposed between the second layer32of the main pole30and the heat sink46. The nonmagnetic metal film47has the function of preventing the material of the heat sink46from diffusing into the second layer32, and thereby preventing deterioration of the magnetic properties of the main pole30. For example, the nonmagnetic metal film47is formed of the same material as the nonmagnetic metal film25described in the first embodiment section.

The thermally-assisted magnetic recording head further includes a dielectric layer48in place of the nonmagnetic metal film36described in the first embodiment section. The dielectric layer48is shown inFIG. 33AandFIG. 33Bto be described later. The dielectric layer48is interposed between the heat sink34and the first layer41of the first yoke portion40. The dielectric layer48is formed of alumina, for example. In the present embodiment, the first layer41has an end face facing toward the medium facing surface80and located at a distance from the medium facing surface80.

In the present embodiment, the heat sink46is located closer to the plasmon generator20and the first layer31than is the heat sink34. This allows for more effective dissipation of the heat generated at the plasmon generator20and the heat transferred from the plasmon generator20to the first layer31outward from the plasmon generator20and the first layer31.

A method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment will now be described with reference toFIG. 26AthroughFIG. 33B.FIG. 26AthroughFIG. 33Beach show a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head.FIG. 26AthroughFIG. 33Bomit the illustration of portions located below the cladding layer18. FIG. nA (n is an integer between26and33inclusive) shows a cross section that intersects the front end face30aof the main pole30and that is perpendicular to the medium facing surface80and to the top surface1a(seeFIG. 5andFIG. 6) of the substrate1. FIG. nB shows a cross section of the stack taken at the location at which the medium facing surface80is to be formed.

The method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment is the same as the method according to the first embodiment up to the step shown inFIG. 17AandFIG. 17B.FIG. 26AandFIG. 26Bshow the next step. In this step, a portion of the surrounding layer27is etched by wet etching, for example. This etching continues until the top surface of the etched surrounding layer27reaches the level that is closer to the top surface1a(seeFIG. 5andFIG. 6) of the substrate1than is the first flat portion31e1(seeFIG. 25) of the top surface31eof the first layer31of the main pole30to be formed later. In the example shown inFIG. 26AandFIG. 26B, the top surface of the etched surrounding layer27is farther from the top surface1aof the substrate1than is the top surface of the multilayer film section21of the plasmon generator20.

FIG. 27AandFIG. 27Bshow the next step. In this step, first, a nonmagnetic metal layer46P for use to form the heat sink46is formed to cover the metal section22of the plasmon generator20, the surrounding layer27and the first magnetic layer31P. As has been described in the first embodiment section, the first magnetic layer31P is a magnetic layer for use to form the first layer31of the main pole30. Then, the nonmagnetic metal layer46P is polished by, for example, CMP, until the first magnetic layer31P is exposed.

FIG. 28AandFIG. 28Bshow the next step. In this step, first, a photoresist mask86is formed on the first magnetic layer31P and the nonmagnetic metal layer46P at a location apart from the location at which the medium facing surface80is to be formed. The photoresist mask86is formed by patterning a photoresist layer by photolithography. Then, respective portions of the dielectric film26, the first magnetic layer31P and the nonmagnetic metal layer46P are etched by, for example, RIE or IBE using the photoresist mask86so as to provide the first magnetic layer31P with the first flat portion31e1and the inclined portion31e2of the top surface31eof the first layer31. This etching makes the nonmagnetic metal layer46P into the heat sink46. The photoresist mask86is then removed.

FIG. 29AandFIG. 29Bshow the next step. In this step, first, in the same manner as the step shown inFIG. 19AandFIG. 19B, the cladding layer18and the surrounding layer27are etched and then the third layers of the coupling sections13A and13B shown inFIG. 5are formed. Next, the nonmagnetic metal film47with an opening for exposing the top surface of the first magnetic layer31P is formed on the heat sink46. Then, the second magnetic layer32P for use to form the second layer32of the main pole30is formed on the first magnetic layer31P and the nonmagnetic metal film47. The second magnetic layer32P has the same shape as in the first embodiment.

FIG. 30AandFIG. 30Bshow the next step. In this step, first, the first magnetic layer31P and the nonmagnetic metal film47are etched by, for example, IBE, using the second magnetic layer32P as an etching mask. This etching makes the first magnetic layer31P into the first layer31. Next, the nonmagnetic metal film33is formed to cover the metal section22of the plasmon generator20, the surrounding layer27, the first layer31, the second magnetic layer32P and the heat sink46.

FIG. 31AandFIG. 31Bshow the next step. In this step, a nonmagnetic metal layer34P for use to form the heat sink34is formed on the nonmagnetic metal film33to cover the metal section22of the plasmon generator20, the surrounding layer27, the second magnetic layer32P and the heat sink46.

FIG. 32AandFIG. 32Bshow the next step. In this step, in the same manner as the step shown inFIG. 22AandFIG. 22A, the dielectric layer35is formed and then the third layers of the coupling sections13A and13B, the nonmagnetic metal film33, the second magnetic layer32P, the nonmagnetic metal layer34P and the dielectric layer35are polished. This polishing makes the second magnetic layer32P into the second layer32, and thereby completes the main pole30. Further, this polishing makes the nonmagnetic metal layer34P into the heat sink34.

FIG. 33AandFIG. 33Bshow the next step. In this step, first, the dielectric layer48is formed over the entire top surface of the stack. The dielectric layer48is then selectively etched to form therein an opening for exposing the top surface of the second layer32and openings for exposing the top surfaces of the third layers of the coupling sections13A and13B. Then, the first layer41of the first yoke portion40is formed on the second layer32and the dielectric layer48, and the coupling layer37(seeFIG. 5) is formed on the third layers of the coupling sections13A and13B and the dielectric layer35. Next, the dielectric layer45is formed over the entire top surface of the stack. The dielectric layer45is then polished by, for example, CMP, until the first layer41and the coupling layer37are exposed. The subsequent steps are the same as in the first embodiment.

Third Embodiment

A thermally-assisted magnetic recording head according to a third embodiment of the invention will now be described. In the present embodiment, the main pole30is constituted not by the first layer31and the second layer32but by a single magnetic layer. The shape and location of the main pole30of the present embodiment are the same as those of the main pole30of the first embodiment.

In the present embodiment, as shown inFIG. 3, the first edge E1of the first end face portion31aof the main pole30and the third edge E3of the near-field light generating surface20aare located on the first imaginary straight line L1, while the second edge E2of the first end face portion31aand the fourth edge E4of the near-field light generating surface20aare located on the second imaginary straight line L2, as in the first embodiment.

A method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment will now be described with reference toFIG. 34toFIG. 37.FIG. 34toFIG. 37each illustrate a stack of layers formed in the process of manufacturing the thermally-assisted magnetic recording head.FIG. 34toFIG. 37omit the illustration of portions located below the cladding layer18.FIG. 34toFIG. 37each show a cross section of the stack taken at the location at which the medium facing surface80is to be formed.

The method of manufacturing the thermally-assisted magnetic recording head according to the present embodiment is the same as the method according to the first embodiment up to the step shown inFIG. 12AandFIG. 12B.FIG. 34shows the next step. In this step, first, the nonmagnetic metal film25is formed by, for example, sputtering, on the dielectric layer24and the initial metal section22P (seeFIG. 12B) which will later become the metal section22of the plasmon generator20. Then, an etching mask87for patterning the initial plasmon generator constituted by the initial multilayer film section21P and the initial metal section22P is formed on the nonmagnetic metal film25. The etching mask87is formed by patterning a photoresist layer by photolithography. The etching mask87has a planar shape corresponding to that of the plasmon generator20.

FIG. 35shows the next step. In this step, first, the nonmagnetic metal film25, the dielectric layer24, the initial plasmon generator and the adhesion layer19are etched by, for example, RIE or IBE, using the etching mask87so that the etching makes the initial plasmon generator into the plasmon generator20.

Next, the dielectric film26is formed to cover the adhesion layer19, the plasmon generator20(the multilayer film section21and the metal section22), the dielectric layer24, the nonmagnetic metal film25and the etching mask87. The surrounding layer27is then formed around the plasmon generator20and the etching mask87. More specifically, first, in the presence of the etching mask87, a dielectric layer that will later become the surrounding layer27is formed over the entire top surface of the stack. Then, the dielectric film26, the dielectric layer and the etching mask87are polished by, for example, CMP, until a portion of the nonmagnetic metal film25that lies on the flat portion of the top surface of the metal section22(seeFIG. 4) of the plasmon generator20is exposed. A portion of the dielectric layer, the portion remaining around the plasmon generator20and the etching mask87, constitutes the surrounding layer27.

FIG. 35shows the next step. In this step, the etching mask87is removed so that a recess88is formed by the plasmon generator20and the surrounding layer27.

FIG. 36shows the next step. In this step, first, the cladding layer18and the surrounding layer27are selectively etched to form therein two openings for exposing the top surfaces of the second layers of the coupling sections13A and13B shown inFIG. 5. Then, the third layers of the coupling sections13A and13B are formed on the second layers of the coupling sections13A and13B, respectively. Further, a magnetic layer130P for use to form the main pole30of the present embodiment is formed on the surrounding layer27and the nonmagnetic metal film25such that a portion of the magnetic layer130P is received in the recess88. The third layers of the coupling sections13A and13B and the magnetic layer130P are formed such that their top surfaces are located at a level higher than the top surface of the main pole30of the present embodiment to be formed later.

Next, in the same manner as the step shown inFIG. 20AandFIG. 20B, the nonmagnetic metal film33is formed to cover the nonmagnetic metal film25, the surrounding layer27and the magnetic layer130P. Then, in the same manner as the step shown inFIG. 21AandFIG. 21B, the nonmagnetic metal layer34P for use to form the heat sink34is formed on the nonmagnetic metal film33so as to cover the metal section22of the plasmon generator20, the surrounding layer27and the magnetic layer130P. Next, in the same manner as the step shown inFIG. 22AandFIG. 22B, the dielectric layer35is formed over the entire top surface of the stack and then the third layers of the coupling sections13A and13B, the nonmagnetic metal film33, the magnetic layer130P, the nonmagnetic metal layer34P and the dielectric layer35are polished by, for example, CMP, until the level of the top surface of the main pole30is reached. This polishing makes the magnetic layer130P into the main pole30of the present embodiment, and makes the nonmagnetic metal layer34P into the heat sink34. The subsequent steps are the same as in the first embodiment.

According to the present embodiment, the recess88is formed by removing the etching mask87which has been used for patterning the plasmon generator20, and the magnetic layer130P for use to form the main pole30is formed such that a portion thereof is received in the recess88. This makes it possible to form the plasmon generator20and the main pole30in a self-aligned manner so that the first and second edges E1and E2of the first end face portion31aof the front end face30aof the main pole30of the present embodiment and the third and fourth edges E3and E4of the near-field light generating surface20aof the plasmon generator20are brought into the previously described positional relationship with each other.

Fourth Embodiment

A thermally-assisted magnetic recording head according to a fourth embodiment of the invention will now be described with reference toFIG. 38toFIG. 42.FIG. 38is a perspective view showing the main part of the thermally-assisted magnetic recording head.FIG. 39is a cross-sectional view showing the configuration of the thermally-assisted magnetic recording head.FIG. 40is a front view showing the medium facing surface of the thermally-assisted magnetic recording head.FIG. 41is a plan view showing a first layer of the coil of the present embodiment.FIG. 42is a plan view showing a second layer of the coil of the present embodiment.

The configuration of the thermally-assisted magnetic recording head according to the present embodiment differs from the first embodiment in the following ways. The thermally-assisted magnetic recording head according to the present embodiment includes a shield61formed of a magnetic material, in place of the shield12. Further, the components of the return path section R of the first embodiment other than the first yoke portion40, that is, the return pole layer11, the coupling sections13A and13B, and the coupling layers37to39, are eliminated from the present embodiment. Instead, the return path section R of the present embodiment includes a second yoke portion69A, a first columnar portion70, a second columnar portion63, and a third columnar portion64. Further, the present embodiment is not provided with the non-illustrated insulating layer and the insulating layer14around the return pole layer11.

The shield61lies on the nonmagnetic layer10. As shown inFIG. 38, the shield61has an end face61alocated in the medium facing surface80, a rear end face61bopposite to the end face61a, and a top surface61c. The front end face30aof the main pole30and the end face61aof the shield61are at locations different from each other in the direction of travel of the recording medium90. In the present embodiment, the end face61aof the shield61is located on the rear side in the direction of travel of the recording medium90relative to the front end face30aof the main pole30.

The shield61includes a central portion61A, a first side portion61B and a second side portion61C, the first and second side portions61B and61C being located on opposite sides of the central portion61A in the track width direction (the X direction). The length of the central portion61A in the direction perpendicular to the medium facing surface80is constant regardless of position along the track width direction. The maximum length of each of the side portions61B and61C in the direction perpendicular to the medium facing surface80is greater than the length of the central portion61A in that direction.

The thermally-assisted magnetic recording head according to the present embodiment includes an insulating layer62lying on the nonmagnetic layer10and surrounding the shield61. The insulating layer62is formed of alumina, for example.

The thermally-assisted magnetic recording head according to the present embodiment further includes a magnetic layer69formed of a magnetic material. The magnetic layer69is embedded in the dielectric layer45. The magnetic layer69is located at a predetermined distance from the first layer41of the first yoke portion40.

As shown inFIG. 38, the magnetic layer69has a front end face69afacing toward the medium facing surface80, a bottom surface69b, and a top surface69c. The front end face69aof the magnetic layer69includes a first portion69a1, a second portion69a2and a third portion69a3, the second and third portions69a2and69a3being located on opposite sides of the first portion69a1in the track width direction. The first portion69a1is shaped to be recessed such that the track-widthwise center of the first portion69a1is farthest from the medium facing surface80. The first portion69a1is disposed to surround the first layer41of the first yoke portion40. The second and third portions69a2and69a3are located in the medium facing surface80.

The magnetic layer69includes the second yoke portion69A as its main portion. The magnetic layer69further includes two coupling sections69B and69C coupled to the second yoke portion69A, the two coupling sections69B and69C being located on opposite sides of the first layer41of the first yoke portion40in the track width direction in the vicinity of the medium facing surface80. InFIG. 38the boundaries between the second yoke portion69A and the coupling sections69B and69C are indicated in dotted lines. The coupling section69B includes the second portion69a2of the front end face69a. The coupling section69C includes the third portion69a3of the front end face69a.

The thermally-assisted magnetic recording head according to the present embodiment further includes four magnetic layers65,66,67and68each formed of a magnetic material. The magnetic layers65and67are embedded in the cladding layers15and17. The magnetic layers65and67are located on opposite sides of the core16in the track width direction in the vicinity of the medium facing surface80. The magnetic layers66and68are located on the magnetic layers65and67, respectively, and are embedded in the cladding layer18, the surrounding layer27and the dielectric layer35. The magnetic layers66and68are located on opposite sides of the plasmon generator20and the main pole30in the track width direction in the vicinity of the medium facing surface80.

The magnetic layers65and66penetrate the cladding layers15,17and18, the surrounding layer27and the dielectric layer35, and connect a portion of the shield61and a portion of the magnetic layer69to each other. Each of the magnetic layers65and66has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the magnetic layer65is in contact with a portion of the top surface61cof the shield61that is included in the first side portion61B. The top surface of the magnetic layer65is in contact with the bottom surface of the magnetic layer66. The top surface of the magnetic layer66is in contact with a portion of the bottom surface69bof the magnetic layer69that is included in the coupling section69B.

The magnetic layers67and68penetrate the cladding layers15,17and18, the surrounding layer27and the dielectric layer35, and connect another portion of the shield61and another portion of the magnetic layer69to each other. Each of the magnetic layers67and68has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the magnetic layer67is in contact with a portion of the top surface61cof the shield61that is included in the second side portion61C. The top surface of the magnetic layer67is in contact with the bottom surface of the magnetic layer68. The top surface of the magnetic layer68is in contact with a portion of the bottom surface69bof the magnetic layer69that is included in the coupling section69C.

The second columnar portion63is constituted by the magnetic layers65and66and the coupling section69B of the magnetic layer69. The third columnar portion64is constituted by the magnetic layers67and68and the coupling section69C of the magnetic layer69. As shown inFIG. 38andFIG. 40, the second columnar portion63and the third columnar portion64are located on opposite sides of the plasmon generator20and the main pole30in the track width direction and spaced from the plasmon generator20and the main pole30.

As described above, since each of the magnetic layers65to69is formed of magnetic metal, each of the second and third columnar portions63and64is also formed of magnetic metal.

The first columnar portion70has a first end70aand a second end70bopposite to each other in the direction of travel of the recording medium90. In the present embodiment, the first end70alies at the front-side end of the first columnar portion70in the direction of travel of the recording medium90, i.e., the trailing-side end of the first columnar portion70, whereas the second end70blies at the rear-side end of the first columnar portion70in the direction of travel of the recording medium90, i.e., the leading-side end of the first columnar portion70.

The first columnar portion70includes a first layer71and a second layer72. The first layer71includes the second end70band lies on a portion of the top surface69cof the magnetic layer69at a location farther from the medium facing surface80than the main pole30. The second layer72includes the first end70aand lies on the first layer71.

In the present embodiment, the first layer51of the coil50is wound approximately three times around the first layer71of the first columnar portion70. The second layer52of the coil50is wound approximately three times around the second layer72of the first columnar portion70. The fourth layer44of the first yoke portion40lies on the third layer43of the first yoke portion40, the second layer72of the first columnar portion70and the insulating layer58.

As has been described, the return path section R of the present embodiment includes the first yoke portion40, the second yoke portion69A, the first columnar portion70, the second columnar portion63, and the third columnar portion64. As shown inFIG. 38andFIG. 39, the first yoke portion40, the second yoke portion69A and the first columnar portion70are located on the same side in the direction of travel of the recording medium90relative to the core16. In the present embodiment, the first yoke portion40, the second yoke portion69A and the first columnar portion70are located on the trailing side, i.e., the front side in the direction of travel of the recording medium90, relative to the core16. The first columnar portion70has the first end70aand the second end70b, and is located away from the medium facing surface80. As shown inFIG. 38, the second and third columnar portions63and64are located closer to the medium facing surface80than is the first columnar portion70.

The first yoke portion40connects the main pole30to the first end70aof the first columnar portion70. The second columnar portion63and the third columnar portion64are located on opposite sides of the plasmon generator20in the track width direction and are connected to the shield61. The second yoke portion69A is connected to the second end70bof the first columnar portion70, and is connected to the shield61via the second and third columnar portions63and64.

The shield61has the same functions as those of the shield12described in the first embodiment section. Specifically, the shield61has the functions of capturing a disturbance magnetic field applied to the thermally-assisted magnetic recording head from the outside thereof; capturing a magnetic flux that is produced from the front end face30aof the main pole30and spreads in directions other than the direction perpendicular to the plane of the recording medium90, and thereby preventing the magnetic flux from reaching the recording medium90; and allowing a magnetic flux that has been produced from the front end face30aof the main pole30and has magnetized a portion of the recording medium90to flow back to the main pole30.

The shape and location of the coil50of the present embodiment will now be described in detail with reference toFIG. 41andFIG. 42. As shown inFIG. 41, the first layer51of the coil50is wound approximately three times around the first layer71of the first columnar portion70. The first layer51includes the coil connection51E described in the first embodiment section, and further includes three conductor portions (hereinafter referred to as linear conductor portions)51A,51B and51C interposed between the first layer71of the first columnar portion70and the medium facing surface80and extending linearly in parallel to the medium facing surface80. The linear conductor portions51A,51B and51C are arranged in this order along the direction perpendicular to the medium facing surface80, the linear conductor portion51A being closest to the medium facing surface80. Each of the linear conductor portions51A,51B and51C has a constant width in the direction perpendicular to the medium facing surface80(the Y direction). InFIG. 41, the locations of opposite ends of each of the linear conductor portions51A,51B and51C in the track width direction (the X direction) are indicated in dotted lines. This also applies to other drawings that show other linear conductor portions.

As shown inFIG. 42, the second layer52of the coil50is wound approximately three times around the second layer72of the first columnar portion70. The second layer52includes the coil connection52S described in the first embodiment section, and further includes three linear conductor portions52A,52B and52C interposed between the second layer72of the first columnar portion70and the medium facing surface80. Each of the linear conductor portions52A,52B and52C has a constant width in the direction perpendicular to the medium facing surface80(the Y direction).

The specific functions and effects of the thermally-assisted magnetic recording head according to the present embodiment will now be described. In the present embodiment, the near-field light generating surface20aof the plasmon generator20is located between the front end face30aof the main pole30and the end face61aof the shield61. A portion of the core16is located in the vicinity of the plasmon generator20. The core16and the return path section R are configured to intersect each other without contacting each other. More specifically, the second and third columnar portions63and64of the return path section R are located on opposite sides of the core16in the track width direction without contacting the core16.

In the present embodiment, the first yoke portion40, the second yoke portion69A and the first columnar portion70are located on the same side in the direction of travel of the recording medium90relative to the core16, and the coil50is wound around the first columnar portion70. The present embodiment allows the first columnar portion70to be small in width in the track width direction regardless of distance between the respective outer ends of the second and third columnar portions63and64in the track width direction. The present embodiment thus allows the coil50to be small in entire length.

In order to improve the write characteristics in high frequency bands, it is desirable that the magnetic path formed by the main pole30and the return path section R be reduced in length. To achieve this, it is effective to bring the first columnar portion70into close proximity to the medium facing surface80. In the present embodiment, the coil50is wound around the first columnar portion70which is small in width in the track width direction. Accordingly, even if the first columnar portion70is brought into close proximity to the medium facing surface80, it is possible to avoid an increase in length of each of the linear conductor portions51A,51B and51C of the first layer51of the coil50located between the first layer71of the first columnar portion70and the medium facing surface80and an increase in length of each of the linear conductor portions52A,52B and52C of the second layer52of the coil50located between the second layer72of the first columnar portion70and the medium facing surface80. The present embodiment thus allows the first columnar portion70to be located close to the medium facing surface80without causing a significant increase in resistance of the coil50. Consequently, the present embodiment makes it possible to reduce the entire length of the coil50while reducing the length of the magnetic path. The present embodiment is thus able to provide a thermally-assisted magnetic recording head that exhibits excellent write characteristics in high frequency bands and has the coil50of low resistance.

Further, the present embodiment allows the coil50to have a low heating value because of its low resistance. This makes it possible to prevent the occurrence of a problem that the components around the coil50may expand to cause part of the medium facing surface80to protrude toward the recording medium90and thus become more likely to collide with the recording medium90. Further, the present embodiment allows for a reduction in the distance between the medium facing surface80and the recording medium90for improvements in write characteristics such as the overwrite property.

Fifth Embodiment

A thermally-assisted magnetic recording head according to a fifth embodiment of the invention will now be described with reference toFIG. 43.FIG. 43is a front view showing the main part of the thermally-assisted magnetic recording head.FIG. 43omits the illustration of the adhesion layer19, the nonmagnetic metal films25and33and the dielectric film26described in the first embodiment section.

The thermally-assisted magnetic recording head according to the present embodiment is configured differently than the first embodiment as described below. The thermally-assisted magnetic recording head according to the present embodiment includes a shield120formed of a magnetic material, in place of the shield12of the first embodiment. The shield120includes a leading shield121, a first side shield124, a second side shield125, a first coupling section122and a second coupling section123.

The leading shield121is located on the leading side, i.e., the rear side in the direction of travel of the recording medium90, relative to the core16. In the present embodiment, the leading shield121lies on the return pole layer11shown inFIG. 5andFIG. 6. The leading shield121has an end face121alocated in the medium facing surface80, a top surface, and a bottom surface. The end face121ais located on the leading side, i.e., the rear side in the direction of travel of the recording medium90, relative to the front end face16aof the core16. The remainder of features of the leading shield121are the same as those of the shield12of the first embodiment.

The first and second side shields124and125are located on opposite sides of the first layer31of the main pole30in the track width direction (the X direction). In the present embodiment, the first and second side shields124and125are embedded in the cladding layer18and the surrounding layer27. The surrounding layer27and the dielectric film26(seeFIG. 3) are interposed between the first layer31and the first and second side shields124,125. The first side shield124has a first side shield end face124alocated in the medium facing surface80, a top surface, and a bottom surface. The second side shield125has a second side shield end face125alocated in the medium facing surface80, a top surface, and a bottom surface. The first and second side shield end faces124aand125aare located on opposite sides of the first end face portion31aof the front end face30aof the main pole30in the track width direction.

The first and second coupling sections122and123are located on opposite sides of the core16in the track width direction. The first coupling section122penetrates the cladding layers15and17and couples the leading shield121and the first side shield124to each other. The first coupling section122has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the first coupling section122is in contact with a portion of the top surface of the leading shield121. The top surface of the first coupling section122is in contact with the bottom surface of the first side shield124.

The second coupling section123penetrates the cladding layers15and17and couples the leading shield121and the second side shield125to each other. The second coupling section123has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the second coupling section123is in contact with another portion of the top surface of the leading shield121. The top surface of the second coupling section123is in contact with the bottom surface of the second side shield125.

The shield120has an end face located in the medium facing surface80. The end face of the shield120includes the end face121aof the leading shield121, the first side shield end face124aof the first side shield124, and the second side shield end face125aof the second side shield125. In the present embodiment, the near-field light generating surface20aof the plasmon generator20is located between the end face30aof the main pole30and the end face121aof the leading shield121.

The thermally-assisted magnetic recording head according to the present embodiment further includes a nonmagnetic layer49formed of a nonmagnetic material and disposed around the second layer32of the main pole30in the vicinity of the medium facing surface80. In the present embodiment, the heat sink34shown inFIG. 3toFIG. 6is disposed around the nonmagnetic layer49and respective portions of the first layer31and the second layer32at a location apart from the medium facing surface80. The nonmagnetic material used to form the nonmagnetic layer49may be an insulating material or a nonmagnetic metal material. Examples of insulating materials that can be used to form the nonmagnetic layer49include silicon oxide (SiO2) and alumina. Examples of nonmagnetic metal materials that can be used to form the nonmagnetic layer49include Ru and NiCr.

In the example shown inFIG. 43, the width of the second end face portion32aof the front end face30aof the main pole30in the track width direction (the X direction) increases with increasing distance from the first end face portion31a. Alternatively, the width of the second end face portion32amay be constant regardless of distance from the first end face portion31a, as in the first embodiment.

In the present embodiment, the end face of the shield120includes the first and second side shield end faces124aand125alocated on opposite sides of the first end face portion31aof the front end face30aof the main pole30in the track width direction. Thus, the shield120of the present embodiment can capture a magnetic flux produced from the first end face portion31aof the front end face30aof the main pole30and spreading in the track width direction, and can thereby prevent the magnetic flux from reaching the recording medium90. Accordingly, the present embodiment makes it possible to sharpen the distribution of intensity of the write magnetic field in the track width direction and thereby achieve higher track density, when compared with the case where the first and second side shield end faces124aand125aare not provided. The present embodiment further makes it possible to form a magnetization transition region into a shape approximating a rectilinear shape, rather than a curved shape, on the recording medium90and thereby achieve higher linear recording density, when compared with the case where the first and second side shield end faces124aand125aare not provided. According to the present embodiment, the above-described functions and effects combined with the functions and effects described in the first embodiment section allow for further increase in recording density.

Sixth Embodiment

A thermally-assisted magnetic recording head according to a sixth embodiment of the invention will now be described with reference toFIG. 44.FIG. 44is a front view showing the main part of the thermally-assisted magnetic recording head.FIG. 44omits the illustration of the adhesion layer19, the nonmagnetic metal films25and33and the dielectric film26described in the fourth (first) embodiment section.

The thermally-assisted magnetic recording head according to the present embodiment is configured differently than the fourth embodiment as described below. The thermally-assisted magnetic recording head according to the present embodiment includes a shield160in place of the shield61of the fourth embodiment, magnetic layers162and163in place of the magnetic layer66of the fourth embodiment, and magnetic layers164and165in place of the magnetic layer68of the fourth embodiment. Each of the shield160and the magnetic layers162to165is formed of a magnetic material. The thermally-assisted magnetic recording head further includes the nonmagnetic layer49described in the fifth embodiment section.

The shield160includes a leading shield161, a first side shield162A, and a second side shield164A. The leading shield161is located on the leading side, i.e., the rear side in the direction of travel of the recording medium90, relative to the core16. In the present embodiment, the leading shield161lies on the nonmagnetic layer10shown inFIG. 39andFIG. 40. The leading shield161has an end face161alocated in the medium facing surface80, a top surface, and a bottom surface. The end face161ais located on the leading side, i.e., the rear side in the direction of travel of the recording medium90, relative to the front end face16aof the core16. The remainder of features of the leading shield161are the same as those of the shield61of the fourth embodiment.

The first and second side shields162A and164A are located on opposite sides of the first layer31of the main pole30in the track width direction (the X direction). In the present embodiment, the first and second side shields162A and164A are embedded in the surrounding layer27. The surrounding layer27and the dielectric film26(seeFIG. 3) are interposed between the first layer31and the first and second side shields162A,164A. The first side shield162A has a first side shield end face162Aa located in the medium facing surface80. The second side shield164A has a second side shield end face164Aa located in the medium facing surface80. The first and second side shield end faces162Aa and164Aa are located on opposite sides of the first end face portion31aof the front end face30aof the main pole30in the track width direction.

The shield160has an end face located in the medium facing surface80. The end face of the shield160includes the end face161aof the leading shield161, the first side shield end face162Aa of the first side shield162A, and the second side shield end face164Aa of the second side shield164. In the present embodiment, the near-field light generating surface20aof the plasmon generator20is located between the end face30aof the main pole30and the end face161aof the leading shield161.

The magnetic layer162includes the first side shield162A described above, and a coupling section162B. InFIG. 44the boundary between the first side shield162A and the coupling section162B is indicated in a dotted line. The magnetic layers65and163and the coupling section162B penetrate the cladding layers15,17and18, the surrounding layer27, the nonmagnetic layer49and the dielectric layer35(seeFIG. 39), and connect a portion of the leading shield161and a portion of the magnetic layer69to each other. Each of the magnetic layers65and163and the coupling section162B has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the magnetic layer65is in contact with a portion of the top surface of the leading shield161. The top surface of the magnetic layer65is in contact with the bottom surface of the coupling section162B. The top surface of the coupling section162B is in contact with the bottom surface of the magnetic layer163. The top surface of the magnetic layer163is in contact with a portion of the bottom surface69b(seeFIG. 38) of the magnetic layer69that is included in the coupling section69B.

The magnetic layer164includes the second side shield164A described above, and a coupling section164B. InFIG. 44the boundary between the second side shield164A and the coupling section164B is indicated in a dotted line. The magnetic layers67and165and the coupling section164B penetrate the cladding layers15,17and18, the surrounding layer27, the nonmagnetic layer49and the dielectric layer35(seeFIG. 39), and connect another portion of the leading shield161and another portion of the magnetic layer69to each other. Each of the magnetic layers67and165and the coupling section164B has a front end face located in the medium facing surface80, a top surface, and a bottom surface. The bottom surface of the magnetic layer67is in contact with another portion of the top surface of the leading shield161. The top surface of the magnetic layer67is in contact with the bottom surface of the coupling section164B. The top surface of the coupling section164B is in contact with the bottom surface of the magnetic layer165. The top surface of the magnetic layer165is in contact with a portion of the bottom surface69b(seeFIG. 38) of the magnetic layer69that is included in the coupling section69C.

In the present embodiment, the second columnar portion63of the return path section R is constituted by the magnetic layers65and163, the coupling section162B of the magnetic layer162, and the coupling section69B of the magnetic layer69. The third columnar portion64of the return path section R is constituted by the magnetic layers67and165, the coupling section164B of the magnetic layer164, and the coupling section69C of the magnetic layer69. The second columnar portion63is connected to the leading shield161and the first side shield162A. The third columnar portion64is connected to the leading shield161and the second side shield164A.

In the example shown inFIG. 44, the width of the second end face portion32aof the front end face30aof the main pole30in the track width direction (the X direction) increases with increasing distance from the first end face portion31a. Alternatively, the width of the second end face portion32amay be constant regardless of distance from the first end face portion31a, as in the first embodiment.

In the present embodiment, the end face of the shield160includes the first and second side shield end faces162Aa and164Aa located on opposite sides of the first end face portion31aof the front end face30aof the main pole30in the track width direction. Consequently, the present embodiment provides functions and effects similar to those resulting from the first and second side shield end faces124aand125adescribed in the fifth embodiment section.

The remainder of configuration, function and effects of the present embodiment are similar to those of the first, fourth or fifth 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 main pole30and the plasmon generator20may be shaped and located as desired, and need not necessarily be as in the respective examples illustrated in the foregoing embodiments.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims and equivalents thereof, the invention may be practiced in other than the foregoing most preferable embodiments.