JP4193847B2 - THIN FILM MAGNETIC HEAD HAVING NEAR FIELD LIGHT GENERATING LAYER AND THERMAL EXPANSION PROJECTING LAYER, HEAD GIMBAL ASSY - Google Patents

Description

  The present invention relates to a thin film magnetic head for writing and reading a signal magnetic field, a head gimbal assembly (HGA) including the thin film magnetic head, and a magnetic disk device including the HGA. In particular, the present invention relates to a thin film magnetic head for perpendicular magnetic recording in which signals are written by using a near-field light by a heat-assisted magnetic recording method, an HGA including the thin film magnetic head, and a magnetic disk device including the HGA. .

  As the recording density of magnetic disk devices increases, further improvements in performance of thin film magnetic heads are required. As a thin film magnetic head, a composite thin film magnetic head having a structure in which a magnetoresistive (MR) effect element for reading and an electromagnetic coil element for writing are stacked is widely used. Signal data is read from and written to a magnetic disk.

  The magnetic recording medium is a so-called discontinuous body in which magnetic fine particles are aggregated, and each magnetic fine particle has a single magnetic domain structure. Here, one recording bit is composed of a plurality of magnetic fine particles. Therefore, in order to increase the recording density, the magnetic fine particles must be made smaller to reduce the irregularities at the boundaries of the recording bits. However, if the magnetic fine particles are made smaller, a decrease in the thermal stability of magnetization accompanying volume reduction becomes a problem.

A measure of the thermal stability of magnetization is given by K _U V / k _B T. Here, K _U is the magnetic anisotropy energy, V the magnetic microparticle volume of one magnetic particle, k _B the Boltzmann constant, T is the absolute temperature. Making the magnetic fine particles smaller means exactly reducing V, and if it is left as it is, K _U V / k _B T becomes smaller and thermal stability is impaired. As a countermeasure, it is conceivable to increase the K _U simultaneously, increase in K _U results in an increase in the coercive force of the medium. On the other hand, the write magnetic field strength by the magnetic head is almost determined by the saturation magnetic flux density of the soft magnetic material constituting the magnetic pole in the head. Therefore, if the coercive force exceeds an allowable value determined from the limit of the write magnetic field strength, writing becomes impossible.

As a first method for solving the problem of the thermal stability of magnetization, a shift from the in-plane magnetic recording method to the perpendicular magnetic recording method can be considered. In the perpendicular magnetic recording medium, the recording layer thickness can be increased, and as a result, V can be increased to improve the thermal stability. As a second method, use of patterned media can be considered. In normal magnetic recording, as described above, one recording bit is composed of N magnetic fine particles and recorded, but using a patterned medium, one recording bit is set as one area of volume NV. As a result, the thermal stability index becomes K _U NV / k _B T, which is dramatically improved.

As a third method for solving the thermal stability problem, uses a large magnetic material K _U, just before the write field is applied, by applying heat to the medium, writing is performed by reducing the coercive force, the so-called A heat-assisted magnetic recording method has been proposed. This method is very similar to the magneto-optical recording method, but the magneto-optical recording method gives the spatial resolution to the light, whereas the thermally assisted magnetic recording method gives the spatial resolution to the magnetic field.

  As a conventionally proposed thermally assisted magnetic recording system, for example, in Patent Document 1, a metal scatterer having a shape such as a cone formed on a substrate and a dielectric formed around the scatterer are disclosed. A technique relating to an optical recording method using a near-field optical probe provided with a film such as a body is disclosed. Patent Document 2 discloses a technique for recording a superfine magnetic domain signal with a superfine light beam spot on a magneto-optical disk using a head using a solid immersion lens in a recording / reproducing apparatus. Patent Document 3 discloses a configuration in which a metal film having pinholes is provided on an end face of an optical fiber or the like cut obliquely. Further, Patent Document 4 discloses a technique for performing heat assist by irradiating light from a built-in laser element unit to a minute optical aperture facing a medium. Further, in Patent Document 5, a scatterer constituting a near-field optical probe is formed in contact with the main pole of a single magnetic pole write head for perpendicular magnetic recording so that the irradiated surface is perpendicular to the recording medium. The configuration is disclosed. Furthermore, Non-Patent Document 1 forms a recording pattern having a track width of about 70 nm by generating near-field light and a magnetic field using a U-shaped near-field optical probe formed on a quartz slider. Techniques to do this are disclosed.

  Among these technologies, a method for generating near-field light by irradiating a near-field optical probe, a microscopic aperture, or a scatterer with a laser, and heating the medium by this near-field light compares the desired near-field light. It is considered very promising because it is easily obtained.

JP 2001-255254 A JP-A-10-162444 JP 2000-173093 A JP 2001-283404 A JP 2004-158067 A Shintaro Miyanishi et al. “Near-field Assisted Magnetic Recording” IEEE TRANSACTIONS ON MAGNETICS, VOL.41, NO.10, pp. 2817-2821, 2005

  However, in the conventional techniques described in these documents, there has been a problem that the case where the recording layer portion of the recording medium is not sufficiently heated by near-field light may occur.

  Near-field light generally exists only in the immediate vicinity of a near-field optical probe, a minute aperture, or a scatterer, and the substantial existence range is approximately the layer thickness or tip width of the probe or scatterer, or the aperture diameter. Is the size of That is, the electric field strength of the near-field light rapidly attenuates from the substantial existence range toward the magnetic disk. Therefore, even in the present situation where the flying height of the head is 10 nm or less and is very small, the near-field light cannot sufficiently reach the recording layer portion of the recording medium in some cases. As a result, the coercive force of the recording layer portion is not sufficiently lowered during writing, and a writing error may occur.

  Therefore, an object of the present invention is to achieve a thin film magnetic field in which the near-field light generated from the near-field light generating means can sufficiently reach the recording layer portion of the recording medium and sufficiently reduce the coercivity of the recording layer portion during writing. It is an object of the present invention to provide a head, an HGA including the thin film magnetic head, and a magnetic disk device including the HGA.

  Before describing the present invention, the terms used in the specification are defined. In the laminated structure of magnetic head elements formed on the element formation surface of the substrate, the component on the substrate side with respect to the reference layer is assumed to be “below” or “below” the reference layer, which becomes the reference It is assumed that the component on the side in the direction of stacking from the layer is “above” or “above” the reference layer.

According to the present invention, a substrate having a medium facing surface and an element forming surface perpendicular to the medium facing surface, and a writing layer formed on the element forming surface and having a main magnetic pole layer, an auxiliary magnetic pole layer, and a coil layer. An electromagnetic coil element; a near-field light generating layer for generating a near-field light to heat a writing portion of the magnetic recording medium during writing; and an element forming surface to cover the electromagnetic coil element and the near-field light generating layer A thin film magnetic head comprising a coating layer formed thereon ,
Proximity field light generation layer, have a shape tapered toward the head end surface of the bearing surface side, has a near-field light generating portion including a distal end reaching the head end surface of the medium facing surface,
It is formed from a material having a high thermal expansion coefficient than the material constituting the object to be covered layer, be provided close to the near-field light generation portion, one end surface of itself reaches the head end surface of the medium facing surface side A thermal expansion projecting layer that is heated and expanded by receiving near-field light generated from the near-field light generating unit, and projects one end surface of the head that has reached the end surface of the head toward the magnetic recording medium. There is provided a thin film magnetic head further provided with a thermal expansion projecting layer for projecting the tip reaching the head end surface of the near-field light generating unit in the direction of the magnetic recording medium . Here, it is preferable that the material which comprises this thermal expansion protrusion layer is a nonmagnetic metal material.

  When the near-field light generating layer receives laser light, near-field light is generated from the vicinity of the tip, and a part of the near-field light heats the adjacent thermal expansion protruding layer. Here, since the thermal expansion protrusion layer has a larger coefficient of thermal expansion, the thermal expansion protrusion layer expands greatly by this heating and protrudes greatly in the direction of the magnetic disk. By being dragged by this protrusion or expanding itself, the tip of the near-field light generating layer and the end of the main magnetic pole layer also protrude greatly in the direction of the magnetic disk. In this way, the tip of the near-field light generating layer protrudes greatly, so that the near-field light sufficiently reaches the recording layer portion of the magnetic disk, and the coercive force of the recording layer portion is sufficiently reduced during writing. To do. Thereby, stable writing is realized. Further, since the end of the main magnetic pole layer protrudes greatly, the magnetic spacing, which is the magnetic effective distance between this end and the magnetic disk surface, becomes sufficiently small. As a result, the write magnetic field sufficiently reaches the recording layer portion of the magnetic disk, thereby improving the write efficiency.

  The near-field light generating portion is inclined such that the medium facing surface side is raised or lowered with respect to the element forming surface, and at least part of the light receiving surface can be irradiated with light incident from the head end surface opposite to the medium facing surface It is preferable to have. The main magnetic pole layer is located on the side opposite to the light receiving surface, and the thermal expansion projecting layer is formed between the near-field light generating portion of the near-field light generating layer and the end of the main magnetic pole layer on the medium facing surface side. It is preferable to be in contact with or close to the end of the main pole layer on the medium facing surface side.

  Further, the main magnetic pole layer is located on the light receiving surface side, and the main magnetic pole layer and the near-field light generating layer are arranged at the end of the main magnetic pole layer on the medium facing surface side and the medium facing surface side of the near-field light generating layer. It is also preferable that the thermal expansion projecting layer is located on the side opposite to the main magnetic pole layer of the near-field light generating part, only at the tip that has reached the head end surface of the head.

  With such a configuration, the near-field light generating layer, the thermal expansion projecting layer, and the main magnetic pole layer are arranged so as to overlap each other in the same track direction. Can be heated. Further, the thermal expansion projecting layer and the main magnetic pole layer also serve as a heat sink for preventing an excessive temperature rise of the near-field light generating unit itself.

  It is also preferable that the near-field light generating layer further includes a reflecting portion having a reflecting surface parallel to the element formation surface on the side opposite to the medium facing surface of the near-field light generating portion. Such a reflecting surface plays a role of compensating the amount of light received by the light receiving surface by reflecting a part of the laser light incident through the head end surface and directing it toward the light receiving surface. Thereby, the generation efficiency of near-field light improves.

Of the coating layers, it is the medium facing surface area including the optical path to the light receiving surface of the light incident from the head end surface of the opposite side is formed by a SiO ₂ to SiO ₂ or at least one additive element is added Is preferred.

  According to the present invention, the thin film magnetic head described above, a support mechanism for supporting the thin film magnetic head, a signal line for the electromagnetic coil element for writing, and the magnetoresistive effect for reading the thin film magnetic head are provided. And a signal line for the magnetoresistive effect element, and further includes an optical fiber for allowing light to enter from the head end surface opposite to the medium facing surface of the thin film magnetic head. HGA is provided.

  Further, according to the present invention, at least one HGA as described above is provided, at least one magnetic disk, a light source for supplying light to the optical fiber, and a thin film magnetic field for the at least one magnetic disk. There is provided a magnetic disk device further comprising a recording / reproducing and light emission control circuit for controlling write and read operations performed by the head and controlling the light emission operation of the light source.

  According to the thin film magnetic head, the HGA including the thin film magnetic head, and the magnetic disk device including the HGA according to the present invention, the near-field light generated from the near-field light generating layer is sufficiently applied to the recording layer portion of the recording medium. Therefore, the coercive force of the recording layer portion is lowered as much as necessary at the time of writing. Thereby, for example, even in a thin film magnetic head for perpendicular magnetic recording, it is possible to realize heat-assisted magnetic recording that enables stable writing and high writing efficiency.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail, referring an accompanying drawing. In the drawings, the same elements are denoted by the same reference numerals. In addition, the dimensional ratios in the components in the drawings and between the components are arbitrary for easy viewing of the drawings.

  FIG. 1 is a perspective view schematically showing a configuration of a main part in an embodiment of a magnetic disk apparatus according to the present invention.

  In the figure, reference numeral 10 denotes a magnetic disk which is a plurality of magnetic recording media for perpendicular magnetic recording rotating around the rotation axis of a spindle motor 11, and 12 denotes a thin film magnetic head (slider) 21 for perpendicular magnetic recording on a track. The assembly carriage device 13 for positioning controls the writing and reading operations of the thin film magnetic head 21 and further controls the semiconductor laser 18 which is a light source for generating a laser beam for heat assist, which will be described in detail later. The recording / reproducing and light emission control circuits are shown.

  The assembly carriage device 12 is provided with a plurality of drive arms 14. These drive arms 14 can be angularly swung about a pivot bearing shaft 16 by a voice coil motor (VCM) 15 and are stacked in a direction along the shaft 16. An HGA 17 is attached to the tip of each drive arm 14. Each HGA 17 is provided with a slider 21 so as to face the surface of each magnetic disk 10. A single magnetic disk 10, drive arm 14, HGA 17, and slider 21 may be provided.

  The semiconductor laser 18 supplies laser light to the optical fiber 26, and the end cross section of the optical fiber 26 is connected to the position of its active layer by a first fiber holder 19. The wavelength of the oscillation laser is, for example, 800 nm.

  FIG. 2 is a perspective view showing an embodiment of the HGA according to the present invention. Here, FIG. 2A shows the configuration of the HGA 17 facing the magnetic disk, and FIG. 2B shows the configuration of the HGA 17 opposite to the side facing the magnetic disk. .

  As shown in FIG. 2A, the HGA 17 has a slider 21 having a magnetic head element fixed to the tip of the suspension 20, and one end of the wiring member 25 is electrically connected to the terminal electrode of the slider 21. Composed.

  The suspension 20 includes a load beam 22, a flexure 23 having elasticity fixedly supported on the load beam 22, a base plate 24 provided at the base of the load beam 22, and a lead conductor provided on the flexure 23. And the wiring member 25 which consists of the connection pad electrically connected to the both ends is comprised mainly.

  As shown in FIG. 2B, the HGA 17 further includes an optical fiber 26 for allowing laser light to enter from the head end face of the thin film magnetic head 21, as will be described in detail later. The end portion on the light output side of the optical fiber 26 is fixed at a position where the laser light can be incident from a predetermined head end surface of the thin film magnetic head 21 by a second fiber holder 27 provided in the flexure 23. Here, the diameter of the end portion on the light output side of the optical fiber 26 is about 5.0 μm to about 500 μm, and the beam diameter of the emitted laser light is also about 5.0 μm to about 500 μm.

  It is obvious that the suspension structure in the HGA 17 of the present invention is not limited to the structure described above. Although not shown, a semiconductor laser for supplying laser light to the head driving IC chip or the optical fiber 26 may be mounted in the middle of the suspension 20.

  FIG. 3A is a perspective view showing an embodiment of a thin film magnetic head (slider) according to the present invention, which is attached to the tip of the HGA shown in FIG. FIG. 3B is a plan view showing the configuration of the magnetic head element portion in this thin film magnetic head.

  According to FIG. 3A, the thin film magnetic head 21 in the present embodiment includes a slider substrate 210 having an air bearing surface (ABS) 30 which is a medium facing surface processed so as to obtain an appropriate flying height, and a slider substrate. The magnetic head element 32 formed on the element forming surface 31 perpendicular to the ABS 30 of 210, the near-field light generating layer 35 for generating near-field light for heat-assisted magnetic recording, and a magnetic head (not shown) A thermal expansion projecting layer formed between the element 32 and the near-field light generating layer 35 and a total of four signal terminal electrodes 36 and 37 exposed from the layer surface of the coating layer 40 formed on the element forming surface 31 are provided. ing. The signal terminal electrodes 36 and 37 are connected to the MR effect element for reading and the electromagnetic coil element for writing provided in the magnetic head element 32, respectively. Note that the number and position of these signal terminal electrodes are not limited to the form shown in FIG. In the figure, there are four terminal electrodes. However, for example, a configuration in which three electrodes are provided and the ground is grounded to the slider substrate may be employed.

  Here, the light from the optical fiber 26 is incident toward the near-field light generating layer 35 from the head end surface 301 opposite to the head end surface 300 which is on the ABS 30 side and is also a surface facing the magnetic disk. Is done.

  According to FIG. 3B, the magnetic head element 32 includes an MR effect element 33 for reading and an electromagnetic coil element 34 for writing. One end of the MR effect element 33 and the electromagnetic coil element 34 reaches the head end surface 300. During the writing or reading operation, the thin film magnetic head 21 floats hydrodynamically on the surface of the rotating magnetic disk with a predetermined flying height. At this time, when the element ends face the magnetic disk, reading by sensing the signal magnetic field and writing by applying the signal magnetic field are performed.

  In the present embodiment, the near-field light generating layer 35 is provided on the electromagnetic coil element 34 and has a tapered shape toward the head end surface 300 that is a surface facing the magnetic disk. Here, the near-field light generating layer 35 includes a near-field light generating unit 350 that generates near-field light by receiving laser light from the optical fiber 26 and a laser beam from the optical fiber 26 to the near-field light generating unit 350. And a reflecting portion 351 having a reflecting surface 351a for directing.

  The near-field light generating unit 350 includes a tip reaching the head end surface 300, has an isosceles triangular shape, for example, and further has a light receiving surface 350a. When the light receiving surface 350a is irradiated with the laser light from the optical fiber 26, as will be described in detail later, the near-field light having a very strong electric field strength from the tip reaching the head end surface 300 of the near-field light generating unit 350. Occurs. A heat assist operation is performed using the near-field light.

  4A is a cross-sectional view taken along the line AA of FIG. 3A schematically showing the configuration of the main part of the thin film magnetic head shown in FIG. Note that the number of turns of the coil layer in the figure is shown to be smaller than the actual number of turns in order to simplify the drawing.

  As shown in FIG. 4A, the MR effect element 33 includes an MR effect multilayer 332 and a lower electrode layer 330 and an upper electrode layer 334 disposed at positions sandwiching the multilayer. The MR effect multilayer 332 is a tunnel magnetoresistive (TMR) effect multilayer film in which a magnetization free layer and a magnetization fixed layer are sandwiched with a tunnel barrier layer sandwiched therebetween, a perpendicular conduction type giant magnetoresistance (CPP (Current Perpendicular to Plain) − Any one of a GMR effect multilayer film and an in-plane energization type giant magnetoresistive (CIP (Current In Plain) -GMR) effect multilayer film is provided. In either case, the signal magnetic field from the magnetic disk is sensed with very high sensitivity and reading is performed. When the MR effect multilayer 332 includes a CIP-GMR multilayer film, upper and lower shield layers are provided between the MR effect multilayer and the MR effect multilayer in place of the upper and lower electrode layers 334 and 330, respectively. In addition, an element lead conductor layer for supplying a sense current to the MR effect laminate is provided.

The lower shield layer 330 is laminated on the element formation surface 31 of the slider substrate 210 made of AlTiC (Al ₂ O ₃ —TiC) or the like. For example, NiFe, NiFeCo, CoFe having a thickness of about 0.3 μm to about 3 μm. , FeN or FeZrN. The upper shield layer 334 is made of, for example, NiFe, NiFeCo, CoFe, FeN, or FeZrN having a thickness of about 0.3 μm to about 4 μm. The reproduction gap length, which is the distance between the upper and lower shield layers 334 and 330, is about 0.02 μm to about 1 μm.

  The electromagnetic coil element 34 is for perpendicular magnetic recording, and includes an auxiliary magnetic pole layer 340, a coil layer 341, a coil insulating layer 342, a gap layer 343, and a main magnetic pole layer 344. The main magnetic pole layer 344 is a magnetic path for guiding the magnetic flux induced by the coil layer 341 while converging it to the recording layer of the magnetic disk on which writing is performed. Here, the length (thickness) in the layer thickness direction of the end 344a on the head end surface 300 side of the main magnetic pole layer 344 is smaller than the other portions. As a result, it is possible to generate a fine write magnetic field corresponding to an increase in recording density.

Here, the auxiliary magnetic pole layer 340 is, for example, an alloy composed of any two or three of Ni, Fe and Co having a thickness of about 0.5 μm to about 5 μm, or a predetermined element containing these as a main component. It is formed from the alloy etc. which were made. The coil layer 341 is made of, for example, Cu having a thickness of about 0.5 μm to about 3 μm. The coil insulating layer 342 is formed of, for example, a heat-cured resist layer having a thickness of about 0.1 μm to about 5 μm. The gap layer 343 is made of, for example, Al ₂ O ₃ or DLC having a thickness of about 0.01 μm to about 0.5 μm. The main magnetic pole layer 344 has, for example, a total thickness of about 0.01 μm to about 0.5 μm at an end portion on the ABS side, and a total thickness of other than the end portion is about 0.5 μm to about 3.0 μm. It is formed from an alloy composed of any two or three of Ni, Fe, and Co, or an alloy to which a predetermined element is added as a main component thereof.

  An inter-element shield layer and / or a backing coil may be further formed between the MR effect element 33 and the electromagnetic coil element 34. The backing coil generates a magnetic flux that is generated from the electromagnetic coil element 34 and cancels the magnetic flux loop that passes through the upper and lower electrode layers of the MR effect element 33, thereby erasing a wide area adjacent track that is an unnecessary write or erase operation on the magnetic disk. (WATE) phenomenon is suppressed. Note that the coil layer 341 is one layer in FIG. 4A, but may be two or more layers or a helical coil.

  Also in FIG. 4A, the near-field light generating layer 35 is added with Au, Pd, Pt, Rh, Ir, or an alloy made of some combination thereof, Al, Cu, or the like. A near-field light generating part 350 and a reflecting part 351 made of such an alloy are provided. The light receiving surface 350a of the near-field light generating unit 350 is inclined such that the head end surface 300 side is raised with respect to the element forming surface 31, and at least a part of the laser light incident from the optical fiber 26 via the head end surface 301 is included. It is formed at a position where it can be irradiated. In the actual heat assist operation, when coherent laser light is irradiated from the optical fiber 26 to the light receiving surface 350a of the near-field light generating unit 350 via the head end surface 301, internal free electrons such as Au are laser light. Plasmons are excited by being forced to vibrate uniformly by the electric field. This plasmon propagates toward the tip 35a of the near-field light generator 350, which is the apex on the head end surface 300 side, and generates near-field light having a very strong electric field strength in the vicinity of the tip 35a. This near field light heats the opposing local portion of the magnetic disk surface. As a result, the coercive force of this local portion is reduced to a size that allows writing by a write magnetic field, so that even if a high coercivity magnetic disk for high-density recording is used, writing by the electromagnetic coil element 34 is possible. Become.

Actually, by applying such a heat-assisted magnetic recording system, writing is performed on a magnetic disk having a high coercive force by using a thin film magnetic head for perpendicular magnetic recording, and the recording bits are made extremely fine, thereby obtaining 1 Tbits. / In ^Second class recording density can be achieved.

  The reflection portion 351 is provided on the side opposite to the head end surface 300 of the near-field light generation portion 350 and has a reflection surface 351 a parallel to the element formation surface 31. The reflecting surface 351a plays a role of supplementing the amount of light received by the light receiving surface 350a by reflecting a part of the laser light incident from the optical fiber 26 through the head end surface 301 and directing it toward the light receiving surface 350a. Thereby, the generation efficiency of near-field light improves.

  The near-field light generating layer 35 is made of Au or the like as described above, and the layer thickness is, for example, about 50 nm to about 500 nm. The distance from the head end surface 300 to the opposite end is, for example, about 10 μm to about 500 μm. Further, the width in the track width direction at the reflecting portion 351 is, for example, about 20 μm to about 500 μm. Further, the width of the tip 35a is about 15 nm to about 40 nm. From the tip 35a of such a near-field light generating layer, near-field light having a width approximately equal to the layer thickness or the width of the tip is generated. Since the electric field intensity of the near-field light is exponentially attenuated in a region of this width or more, the recording layer portion can be heated very locally. Further, the near-field light is present in the region from the tip toward the magnetic disk direction up to the layer thickness or the width of the tip. Accordingly, in the present situation where the flying height is 10 nm or less, the near-field light sufficiently reaches the recording layer portion.

  The covering layer 40 is formed on the element forming surface 31 so as to cover the MR effect element 33, the electromagnetic coil element 34, and the near-field light generating layer 35. The covering layer 40 includes a first covering layer 400 that occupies a region from the element forming surface to the upper surface excluding the end portion 344a of the main magnetic pole layer 344 in the stacking direction (direction perpendicular to the element forming surface 31). It has a laminated structure of a second coating layer 401 that occupies a region from the upper surface to above the near-field light generating portion, and a third coating layer 402 that occupies a region on this region.

Here, the second coating layer 401 includes all of the optical path from the head end surface 301 to the light receiving surface 350a, and has a sufficiently high transmittance of the laser light generated from the semiconductor laser 18 (FIG. 1). , SiO ₂ or an oxide containing SiO ₂ as a main component. As a result, the attenuation of the laser light incident on the thin film magnetic head can be made as small as possible. As a result, the amount of light received by the light receiving surface 350a is increased and the near-field light generation efficiency is improved. The first and third coating layers 400 and 402 are made of Al ₂ O ₃ that is usually used for coating. Note that the second coating layer 401 only needs to include an optical path to the light receiving surface 350a. For example, the second coating layer 401 may be a layer having a width in a predetermined track width direction including the optical path. In this case, by forming a layer made of Al ₂ O ₃ on both sides in the track width direction of this layer, the adhesion strength between the first and third coating layers sandwiching this layer is increased, and the mechanical strength of the coating layer is increased. Can be maintained sufficiently.

The thermal expansion protruding layer 41 is located between the near-field light generating part 350 of the near-field light generating layer 35 and the end 344a of the main magnetic pole layer 344. The near-field light generating part 350 has a thickness of about It is in close proximity via an insulating layer 42 made of SiO ₂ , Al ₂ O _3, etc. with a thickness of ₃ nm to about 20 nm, and is in direct contact with the end 344 a of the main magnetic pole layer 344. Here, in the present embodiment, the main magnetic pole layer 344 is located on the side opposite to the light receiving surface 350 a of the near-field light generating layer 35 and is provided on the leading side of the near-field light generating layer 35. Furthermore, the thermal expansion protruding layer 41 has a higher coefficient of thermal expansion than an insulating material such as Al ₂ O ₃ and SiO ₂ constituting the coating layer 40, and has Al, Cu, Au, Ti, Ta, Mo, W or Ru, Or it is comprised from nonmagnetic metal materials, such as an alloy which consists of some of these elements. An insulating layer may be provided between the thermal expansion protruding layer 41 and the end portion 344a of the main magnetic pole layer.

  4B is a perspective view showing the configuration of the end portions of the near-field light generating layer 35, the thermal expansion protruding layer 41, and the main magnetic pole layer 344. FIG.

  According to the figure, a part of the near-field light generated in the near-field light generating layer 35 by receiving the laser beam 43 heats the adjacent thermal expansion protruding layer 41. Since the thermal expansion protruding layer 41 has a large coefficient of thermal expansion as described above, it expands greatly by this heating, and in particular, the end surface serving as the head end surface 300 protrudes greatly in the magnetic disk direction. By being dragged by this protrusion or expanding itself, the tip of the near-field light generating layer 35 and the end of the main magnetic pole layer 344 also protrude greatly in the magnetic disk direction. Since the tip of the near-field light generating layer 35 protrudes greatly, the near-field light sufficiently reaches the recording layer portion of the magnetic disk, and the coercive force of the recording layer portion is sufficiently reduced when writing. Further, since the end of the main magnetic pole layer 344 protrudes greatly, the magnetic spacing, which is the magnetic effective distance between this end and the magnetic disk surface, becomes sufficiently small. As a result, the write magnetic field sufficiently reaches the recording layer portion of the magnetic disk, thereby improving the write efficiency.

  Further, since the near-field light generating layer 35, the thermal expansion projecting layer 41, and the main magnetic pole layer 344 overlap each other in the same track direction, the portion (track) to be written on the recording layer of the magnetic disk is surely formed. Heating becomes possible. Further, the thermal expansion protruding layer 41 and the main magnetic pole layer 344 also serve as a heat sink that prevents an excessive temperature rise of the near-field light generating unit 350 itself.

  In the present embodiment, the end 344a of the main magnetic pole layer 344, which is the main generation location of the write magnetic field, is positioned on the leading side of the tip 35a of the near-field light generation portion 350, which is the main generation location of the near-field light. Therefore, the heat assist operation and the write operation are performed almost simultaneously, or the write operation is performed after the recording layer portion that has received the heat assist action has rotated at least once and returned to the head position.

  Further, as described above, the near-field light generator 350 is inclined with respect to the element forming surface 31 such that the head end surface 300 side is raised. Assuming that the inclination is θ, the temperature rise in the recording layer portion of the magnetic disk due to the heat assisting action of the near-field light generator 350 increases as the amount of light received by the light receiving surface increases as the inclination θ increases. In contrast, as the inclination θ increases, the distance between the tip of the near-field light generating unit 350 and the end of the main magnetic pole layer 344 increases, and the deviation between the heating and protruding portion and the writing magnetic field generating portion increases. obtain. If this deviation becomes large, writing may not be stabilized even by heating and protruding operations, and writing efficiency may not be improved, especially when the skew is large, which is not preferable. That is, the value of the inclination θ can be selected with a certain width between the condition for sufficiently reducing the coercive force of the recording layer by thermal assist and the condition for matching the heating protruding portion and the writing portion. . When designing the θ value, even if the laser light from the optical fiber fluctuates within a predetermined range due to flexure vibration or the like, the light receiving surface of the near-field light generating layer is surely required with a certain margin. It is also considered to increase the θ value to some extent so that the quantity can be received. In the embodiment of FIG. 4, θ is about 40 degrees to about 50 degrees.

  FIG. 5 is a cross-sectional view showing various embodiments of the near-field light generating layer and the thermal expansion protruding layer provided in the thin film magnetic head according to the present invention.

  According to FIG. 5A, the thermal expansion protruding layer 52 is formed between the near-field light generating portion 510 of the near-field light generating layer 51 and the end 50a of the main magnetic pole layer 50, as in FIG. Located near the near-field light generator 510 via the insulating layer 53. However, in this embodiment, the end portion 50a of the main magnetic pole layer 50 is formed closer to the near-field light generating portion 510 than the end portion 344a of FIG. 4A, and the upper surface of the end portion 50a is the main magnetic pole layer. 50 coincides with the upper surface. As a result, the distance between the heating protruding portion and the writing portion on the head end surface 300 becomes smaller, and the writing stability and writing efficiency are further improved.

  According to FIG. 5B, the thermal expansion protruding layer 56 is formed between the near-field light generating part 550 of the near-field light generating layer 55 and the end 54a of the main magnetic pole layer 54, as in FIG. Located near the near-field light generator 550 via the insulating layer 57. However, in the present embodiment, the part on the head end surface 300 side of the near-field light generating unit 550 is bent from the other part and is parallel to the element forming surface 31. As a result, the near-field light generating unit 550 generates a necessary near-field light by sufficiently securing the area of the light-receiving surface 550a, and the distance between the heating protruding portion and the writing portion on the head end surface 300 is small. Since it does not increase, the writing stability and writing efficiency are further improved.

  According to FIG. 5C, the light receiving surface 590 a of the near-field light generating part 590 of the near-field light generating layer 59 is inclined so that the head end surface 300 side is lowered with respect to the element forming surface 31. Is formed at a position where at least a part of the laser beam incident through can be irradiated. The main magnetic pole layer 58 is positioned on the leading side of the near-field light generating layer 59 on the light receiving surface 590a side. Further, the main magnetic pole layer 58 and the near-field light generating layer 59 are in contact with each other only at the end 58b of the main magnetic pole layer 58 on the head end surface 300 side and the front end 59a of the near-field light generating layer 59 on the head end surface 300 side. It is close. Further, the thermal expansion projecting layer 60 is provided at a position close to the near-field light generating unit 590 via the insulating layer 61 on the side opposite to the main magnetic pole layer 58 of the near-field light generating unit 590. With the configuration described above, the recording layer portion of the magnetic disk can surely receive the heat assist action by the near-field light generated from the vicinity of the tip 59a of the near-field light generating portion 590. In addition, since the center of protrusion by the thermal expansion protrusion layer 60 is close to both the front end 59a of the near-field light generating layer and the end portion 58a of the main magnetic pole layer, the front end 59a and the end portion 58a are sufficiently protruded. This makes it possible to improve the writing stability and the writing efficiency more reliably.

  In the present embodiment, the light from the optical fiber 26 is emitted toward the region between the main magnetic pole layer 58 and the reflection portion 591 of the near-field light generating layer 59. At this time, not only the reflecting surface 591a but also the upper surface of the main magnetic pole layer 58 reflects part of the incident light and directs it toward the light receiving surface 590a, thereby supplementing the amount of light received by the light receiving surface 590a. Independent of the main magnetic pole layer 58, a reflective layer made of Au, Al, Cu, or an alloy of some combination thereof may be provided in contact with or above the upper surface of the main magnetic pole layer 58. Good.

  Further, as a modification of the embodiment shown in FIGS. 5A to 5C described above, the main magnetic pole layer is provided on the lower side (leading side) of the auxiliary magnetic pole layer, and the near-field light is generated. The layer may be provided on the lower side (leading side) of the main magnetic pole layer. It is obvious that the same effect as that of the above-described embodiment can be obtained even in such a modified mode. In the case of this change mode, in actual writing, immediately after the recording layer portion to be written is subjected to the heat assist action, the writing operation is stably performed on the same portion with high writing efficiency.

  FIG. 6 is a cross-sectional view for explaining an embodiment of a method for forming a near-field light generating part inclined with respect to the thermal expansion protruding layer and the element formation surface. Specifically, in FIGS. 6A to 6C, in the manufacturing process of the thin film magnetic head shown in FIG. 4A, the formation process part of the thermal expansion protruding layer 52 and the near-field light generator 350 is shown. Shown sequentially.

  In FIG. 6A, first, the main magnetic pole main film 80 is formed, and then the main magnetic pole auxiliary film 81 is formed. Here, the end portion of the main magnetic pole main film 80 becomes an end portion on the head end face side of the main magnetic pole layer later. Thereafter, a resist pattern 82 for lift-off is formed on the main magnetic pole auxiliary film 81, and then Al, Cu, Au, Ti, Ta, Mo, W, Ru, or these elements are formed by sputtering or the like. A nonmagnetic metal film such as an alloy made of some of these is formed to form a thermal expansion protruding film 83 having inclined side surfaces. Thereafter, the resist pattern 82 and the nonmagnetic metal film thereon are removed by so-called lift-off.

Next, as shown in FIG. 6B, an insulating film 84 made of SiO ₂ , Al ₂ O _3, etc. and a near-field light generating layer on the main magnetic pole auxiliary film 81 and the thermal expansion protrusion film 83, A near-field light generating film 85 made of Au, Pd, Pt, Rh or Ir, or an alloy made of some combination thereof, or an alloy of these alloys to which Al, Cu or the like is added is formed. Further, a dielectric film 86 to be a coating layer is formed thereon.

  After the wafer substrate process of the thin film magnetic head including the above formation process is completed, the wafer substrate after the formation process is cut to form a bar member in which a plurality of magnetic head elements are arranged in a line. Next, MR height processing is performed to obtain a desired MR height by polishing the bar member. Thereafter, the bar member that has been subjected to MR height processing is cut and separated into individual sliders (thin film magnetic heads), thereby completing the manufacturing process of the thin film magnetic head.

  Here, according to FIG. 6C, the main magnetic pole main film 80, the thermal expansion protruding film 83, the insulating film 84, the near-field light generating film 85, and the dielectric film 86 are ground by the MR height processing described above. Thus, the main magnetic pole layer 344, the thermal expansion protruding layer 41, the insulating layer 42, the near-field light generating layer 35, and the covering layer 40 are completed. Here, the near-field light generator 350 is inclined with respect to the element formation surface as a result of being formed on the inclined side surface of the thermal expansion protrusion film 83.

  FIG. 7 is a block diagram showing a circuit configuration of the recording / reproducing and light emission control circuit 13 of the magnetic disk apparatus shown in FIG.

  In FIG. 7, 90 is a control LSI, 91 is a write gate that receives recording data from the control LSI 90, 92 is a write circuit, 93 is a ROM that stores a control table for operating current values supplied to the semiconductor laser 18, etc. Is a constant current circuit that supplies a sense current to the MR effect element 33, 96 is an amplifier that amplifies the output voltage of the MR effect element 33, 97 is a demodulation circuit that outputs reproduction data to the control LSI 90, and 98 is a temperature. A detector 99 indicates a control circuit for the semiconductor laser 18.

  The recording data output from the control LSI 90 is supplied to the write gate 91. The write gate 91 supplies recording data to the write circuit 92 only when a recording control signal output from the control LSI 90 instructs a writing operation. The write circuit 92 causes a write current to flow through the coil layer 341 in accordance with this recording data, and the electromagnetic coil element 34 writes on the magnetic disk.

  A constant current flows from the constant current circuit 95 to the MR multilayer 332 only when the reproduction control signal output from the control LSI 90 instructs a read operation. The signal reproduced by the MR effect element 33 is amplified by the amplifier 96 and then demodulated by the demodulation circuit 97, and the obtained reproduction data is output to the control LSI 90.

  The laser control circuit 99 receives a laser ON / OFF signal and an operating current control signal output from the control LSI 90. When this laser ON / OFF signal is an on operation instruction, an operating current equal to or higher than the oscillation threshold is applied to the semiconductor laser. The operating current value at this time is controlled to a value corresponding to the operating current control signal. The control LSI 90 generates a laser ON / OFF signal according to the timing of the recording / reproducing operation, and takes into account the temperature measurement values of the recording layer of the magnetic disk and the semiconductor laser 18 by the temperature detector 98, and the like, and controls the ROM 93. The value of the operating current value control signal is determined based on the table. At this time, the protrusion of the thermal expansion protrusion layer 41 due to the near-field light from the near-field light generation layer 35, and the protrusion of the near-field light generation layer 35 and the main magnetic pole layer 344 accompanying this, are slightly different from the start of laser irradiation. It is considered to have a time lag. Specifically, after the laser irradiation, writing is started after a small magnetic spacing sufficient to sufficiently recover the overwrite characteristic is secured.

  Here, the control table includes not only the temperature dependence of the oscillation threshold value and the optical output-operating current characteristic, but also the operating current value and the protrusion of the near-field light generating layer 35 and the main magnetic pole layer 344 by the thermal expansion protruding layer 41. Data on the relationship between the amount and the temperature rise of the recording layer subjected to the heat assisting action, and further the temperature dependence of the coercive force may be included.

  In this way, by providing the laser ON / OFF signal and the operating current value control signal system independently of the recording / reproducing operation control signal system, not only the energization to the semiconductor laser simply linked to the recording operation, More various energization modes can be realized. It is apparent that the circuit configuration of the recording / reproducing and light emission control circuit 13 is not limited to that shown in FIG. The write operation and the read operation may be specified by a signal other than the recording control signal and the reproduction control signal. In addition, it is desirable to energize the semiconductor laser 18 at least during or immediately before the write operation, but it is also possible to energize for a predetermined period in the sequence of the write operation and the read operation.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

1 is a perspective view schematically showing a configuration of a main part in an embodiment of a magnetic disk device according to the present invention. FIG. It is a perspective view which shows one Embodiment of HGA by this invention. FIG. 3 is a perspective view showing an embodiment of a thin film magnetic head according to the present invention mounted on the tip of the HGA shown in FIG. 2, and a plan view showing a configuration of a magnetic head element portion in the thin film magnetic head. FIG. 3A is a cross-sectional view taken along the line AA in FIG. 3A schematically showing the configuration of the main part of the thin film magnetic head shown in FIG. It is a perspective view which shows a structure. It is sectional drawing which shows various embodiment about the near-field light generation layer and thermal expansion protrusion layer with which the thin film magnetic head by this invention is provided. It is sectional drawing explaining one Embodiment of the formation method of the near-field light generation part inclined with respect to a thermal expansion protrusion layer and an element formation surface. FIG. 2 is a block diagram showing a circuit configuration of a recording / reproducing and light emission control circuit of the magnetic disk device shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic disk 11 Spindle motor 12 Assembly carriage apparatus 13 Recording / reproduction | regeneration and light emission control circuit 14 Drive arm 15 Voice coil motor (VCM)
16 Pivot bearing shaft 17 Head gimbal assembly (HGA)
DESCRIPTION OF SYMBOLS 18 Semiconductor laser 19, 27 Fiber holder 20 Suspension 21 Slider 210 Slider substrate 22 Load beam 23 Flexure 24 Base plate 25 Wiring member 26 Optical fiber 30 Air bearing surface (ABS)
300, 301 Head end surface 31 Element formation surface 32 Magnetic head element 33 MR effect element 330 Lower electrode layer 332 MR effect laminate 334 Upper electrode layer 34 Electromagnetic coil element 340, 710 Auxiliary magnetic pole layer 341 Coil layer 342 Coil insulation layer 343 Gap layer 344, 50, 54, 58 Main magnetic pole layer 344a, 50a, 54a, 58a End portion 35, 51, 55, 59 Near-field light generating layer 35a, 59a Tip 350, 510, 550, 590 Near-field light generating portion 350a, 550a 590a Light receiving surface 351, 591 Reflecting portion 351a Reflecting surface 36, 37 Signal terminal electrode 40, 400, 401, 402 Covering layer 41, 52, 56, 60 Thermal expansion protruding layer 42, 53, 57, 61 Insulating layer 43 Laser light 58b end 80 main magnetic pole main film 81 main magnetic pole auxiliary layer 82 resist Pattern 83 thermally expand and protrude film 84 insulating film 85 near-field light generating layer 86 a dielectric layer 90 controls LSI
91 Write gate 92 Write circuit 93 ROM
95 constant current circuit 96 amplifier 97 demodulation circuit 98 temperature detector 99 laser control circuit

Claims (9)

A substrate having a medium facing surface and an element forming surface perpendicular to the medium facing surface, and an electromagnetic coil element for writing formed on the element forming surface and having a main magnetic pole layer, an auxiliary magnetic pole layer, and a coil layer, A near-field light generating layer for heating the writing portion of the magnetic recording medium during writing by generating field light, and formed on the element forming surface so as to cover the electromagnetic coil element and the near-field light generating layer A thin film magnetic head comprising a coated layer,
The near-field light generating layer has a shape tapered toward the head end surface on the medium facing surface side, and includes a near-field light generating portion including a tip reaching the head end surface on the medium facing surface side. ,
Wherein is formed of a high thermal expansion coefficient material than the material constituting the coating layer, it is provided in proximity to the near-field light generation portion, the head end surface of one end surface of its own the medium facing surface A thermal expansion projecting layer that has reached its head end surface in the direction of the magnetic recording medium by being heated and expanded by receiving the near-field light generated from the near-field light generating unit. A thin-film magnetic head, further comprising a thermal expansion projecting layer that projects the tip of the near-field light generating unit that has reached the head end surface in the direction of the magnetic recording medium .   The near-field light generating portion is inclined such that the medium facing surface side is raised or lowered with respect to the element forming surface, and at least a part of the light incident from the head end surface opposite to the medium facing surface can be irradiated. The thin film magnetic head according to claim 1, further comprising a light receiving surface.   The main magnetic pole layer is located on a side opposite to the light receiving surface of the near-field light generating layer, and the thermal expansion projecting layer includes a near-field light generating part of the near-field light generating layer and the main magnetic pole layer. 3. The thin film according to claim 2, wherein the thin film is positioned between the end of the main pole layer and the end of the main magnetic pole layer on the side of the medium facing surface. Magnetic head.   The main magnetic pole layer is positioned on the light receiving surface side of the near-field light generating layer, and the main magnetic pole layer and the near-field light generating layer are connected to the end of the main magnetic pole layer on the medium facing surface side and the Only the tip of the near-field light generating layer reaching the head end surface on the medium facing surface side is in contact with or close to each other, and the thermal expansion protruding layer is the main magnetic pole layer of the near-field light generating unit. The thin film magnetic head according to claim 2, wherein the thin film magnetic head is located on an opposite side.   The near-field light generation layer further includes a reflection portion having a reflection surface parallel to the element formation surface on a side opposite to the medium facing surface of the near-field light generation portion. 5. The thin film magnetic head according to any one of 1 to 4.   6. The thin film magnetic head according to claim 1, wherein the material constituting the thermal expansion protruding layer is a nonmagnetic metal material. Among the covering layer, wherein the bearing surface area including the optical path to the light receiving surface of the light incident from the head end surface of the opposite side is formed by SiO ₂ of SiO ₂ or at least one additive element is added The thin film magnetic head according to claim 1, wherein the thin film magnetic head is provided.   8. The thin film magnetic head according to claim 1, a support mechanism for supporting the thin film magnetic head, a signal line for the electromagnetic coil element for writing, and the thin film magnetic head for reading. The magnetoresistive effect element is provided with a signal line for the magnetoresistive effect element, and light for allowing light to enter from the head end surface opposite to the medium facing surface of the thin film magnetic head. A head gimbal assembly, further comprising a fiber.   9. A head gimbal assembly according to claim 8, comprising at least one magnetic disk, a light source for supplying light to the optical fiber, and the thin film magnetic head for the at least one magnetic disk. And a recording / reproducing and light emission control circuit for controlling the light emission operation of the light source and the magnetic disk apparatus.

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