JP2008159150A - Optical assist type magnetic head, method for manufacturing the same, and magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade the contact due to relative inclination with a magnetic recording medium in an optical assist type magnetic head by near-field light. <P>SOLUTION: The optical assist type magnetic head comprises a 2-group condenser lens system 4 having an objective lens 2, and a hemispherical or super-hemispherical lens 3, and a thin-film magnetic head element 5. The hemispherical or super-hemispherical lens 3 is constituted of a coalescence a lens body 3L constituting a spherical surface side lens and a light transmissive substrate 3S arranged at an opposed face side with the magnetic recording medium 11. The light transmissive substrate 3S is formed by being extended to an outer side than the lens body 3L and the thin-film magnetic head element 5 is formed on the light transmissive substrate 3S. The surface of the light transmissive substrate 3S opposite to the magnetic recording medium 11 is retreated by leaving the central region formed with the thin-film magnetic head element 5 and by having a level difference d1, d2 of two steps so as to part from the magnetic recording medium 11 toward the periphery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optically assisted magnetic head, a manufacturing method thereof, and a magnetic recording apparatus.

There is an increasing demand for high-density recording on information recording media. Even in information recording on magnetic recording media such as magnetic tapes and magnetic disks, ultra-high density recording is required. In this case, perpendicular recording is adopted for miniaturization of recording bits, high resolution is obtained, and the coercivity of the magnetic layer is increased.
Thus, as a magnetic head capable of recording information with a minute magnetic field spot without increasing the signal recording magnetic field with respect to a magnetic recording medium having a high coercive force, the recording portion of the magnetic recording medium is locally localized. There has been proposed an optically assisted magnetic head that raises the temperature by light irradiation and reduces the coercive force here.

  In such optically assisted magnetic recording, it is necessary to increase the recording density, that is, to make the light spot minute in order to form a minute recording bit. In a normal condenser lens, the spot diameter is determined by the wavelength of the light used and the numerical aperture (NA) of the lens. In a normal lens, the numerical aperture is limited, and there is a limit to the miniaturization of the spot diameter. On the other hand, a spot caused by near-field light using a hemispherical lens (SIL: Solid Immersion Lens) or a super hemispherical lens (Super SIL: Super Solid Immersion Lens) having a high refractive index with respect to the wavelength of light to be used is Since the spot diameter is miniaturized, an optically assisted magnetic head using near-field light by this hemispherical lens or super hemispherical lens has also been proposed (see, for example, Patent Documents 1, 2, and 3).

  The optically assisted magnetic head of Patent Document 3 has a two-group condensing lens system including an objective lens and a hemispherical lens or a super hemispherical lens, and the hemispherical lens or the superhemispherical lens is bonded and integrated with the lens body and the light-transmitting substrate. The thin film magnetic head is formed on a light transmissive substrate.

  The manufacturing of this optically assisted magnetic head is the same as forming a thin film magnetic head on the end face of the first block made of an optical member that is transparent to the light of the wavelength used and has a high refractive index, and sandwiches this thin film magnetic head. After joining the 2nd block which consists of an optical member via an optical adhesive agent, planar polishing is carried out and the light transmissive board | substrate of predetermined | prescribed board thickness is formed. Subsequently, the flat-polished hemispherical lens is bonded to the light-transmitting substrate through an optical adhesive.

JP 2006-134513 A JP 2006-139826 A JP 2006-286119 A

  In the above-described optically assisted magnetic head, a thin film magnetic head element facing the surface of the light-transmitting substrate facing the magnetic recording medium is placed at a position several tens of nanometers above the surface of the magnetic medium and a linear velocity of several m / s or more. Recording and playback while moving in At the time of recording and reproduction, it is desired that the light-transmitting substrate does not come into contact with the magnetic medium due to the relative inclination between the magnetic recording medium and the optically assisted magnetic head.

In view of the above-described points, the present invention provides a reliability that prevents the light-transmitting substrate from coming into contact with the magnetic recording medium even if it is inclined relative to the magnetic recording medium within an allowable range during recording or recording / reproducing. A high optically assisted magnetic head and a manufacturing method thereof are provided.
The present invention provides a highly reliable magnetic recording apparatus including the optically assisted magnetic head.

  An optically assisted magnetic head according to the present invention includes an objective lens, a two-group condensing lens system having a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element, and the hemispherical lens or super hemispherical lens is spherical. A lens body that constitutes a side lens and a light-transmitting substrate disposed on the surface facing the magnetic recording medium, and the light-transmitting substrate is formed to extend outward from the lens body. A thin film magnetic head element is formed on the light transmissive substrate, and a surface of the light transmissive substrate facing the magnetic recording medium is directed toward the periphery, leaving a central region on which the thin film magnetic head element is formed. The magnetic recording medium is retracted so as to be separated from the magnetic recording medium by two steps.

  An optically assisted magnetic head manufacturing method according to the present invention is an optically assisted magnetic head comprising an objective lens, a two-group condensing lens system having a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element. In the method, a thin film magnetic head element is disposed on the lens body forming step of the spherical lens portion of the hemispherical lens or super hemispherical lens, and on the side of the lens body facing the magnetic recording medium, A bonding step of bonding a light-transmitting substrate having an extension portion extended outward from the lens body, and a central region where the thin-film magnetic head element is formed on a surface of the light-transmitting substrate facing the magnetic recording medium. A first step forming step for forming a first step, and a central region in which the thin film magnetic head element is formed on a surface of the light transmissive substrate facing the magnetic recording medium; And having a second step forming step of forming a second step, leaving a partial area of the first step.

  A magnetic recording apparatus according to the present invention includes a light source section, a magnetic recording medium placement section, a light-assisted magnetic head, a recording signal power supply section, and an optical path for guiding light from the light source section to the light-assisted magnetic head. The optically assisted magnetic head includes a two-group condensing lens system having an objective lens and a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element. The super hemispherical lens is formed by a combination of a lens body constituting a spherical lens and a light transmissive substrate disposed on the surface facing the magnetic recording medium, and the light transmissive substrate is outside the lens body. A thin film magnetic head element is formed on the light transmissive substrate, and a surface of the light transmissive substrate facing the magnetic recording medium is a central region where the thin film magnetic head element is formed. Leaving, characterized in that formed by retracting a step of two steps away from the magnetic recording medium towards the periphery.

  In the optically assisted magnetic head according to the present invention, the light-transmitting substrate constituting the hemispherical lens or the super hemispherical lens faces the periphery, leaving the central region where the thin film magnetic head element is formed on the surface facing the magnetic recording medium. Since two steps are formed so as to be separated from the magnetic recording medium, contact due to the relative inclination between the optically assisted magnetic head and the magnetic recording medium is unlikely to occur.

According to the optically assisted magnetic head of the present invention, it is possible to avoid contact due to the relative inclination between the optically assisted magnetic head and the magnetic recording medium. Further, by adopting a configuration in which the light-transmitting substrate is formed to extend outward from the lens body, it is possible to provide a light-assisted magnetic head for practical use, for example, an electrode pad can be formed. Therefore, a highly reliable optically assisted magnetic head and a magnetic recording apparatus including the same can be provided.
Further, according to the method for manufacturing an optically assisted magnetic head of the present invention, it is possible to manufacture an optically assisted magnetic head that can avoid contact due to the relative tilt between the optically assisted magnetic head and the magnetic recording medium. it can.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to this example.

  1 (schematic cross-sectional view) and FIG. 2 (partially cutaway perspective view) show an embodiment of an optically assisted magnetic head according to the present invention. As shown in the schematic cross-sectional structure of FIG. 1, the optically assisted magnetic head 1 according to the present embodiment optically includes an objective lens 2, a hemispherical lens (SIL), or a super hemispherical lens (super SIL) (hereinafter referred to as a “semispherical lens”). And a two-group condensing lens system 4 having 3).

  The hemisphere / super hemisphere lens 3 is formed by a joined body of a lens main body (so-called pseudo-hemisphere lens) 3L constituting a spherical lens portion and a light-transmitting substrate 3S disposed on the surface facing the magnetic recording medium 11. Composed. The lens body 3L and the light transmissive substrate 3S are both the same optical member, that is, have a light transmittance with respect to the wavelength of the used light, and have a high refractive index, for example, 1.8 or more, preferably 2 or more. It is comprised by the optical member which has these. As an optical member, members, such as optical glass, GaN, a diamond, can be used, for example. The second group condensing lens system 4 generates near-field light having an effective aperture ratio exceeding 1.0. The thin film magnetic head element 5 is disposed on the light transmissive substrate 3S so that the film surface is along the optical axis direction.

  The light-transmitting substrate 3S having the thin film magnetic head element 5 forms the thin film magnetic head element 5 on the end face of the first block 6a made of an optical member (for example, optical glass) that is transparent to light at the used wavelength and has a high refractive index. After that, the second block 6b made of the same optical member (for example, a glass member) is bonded or welded via an optical adhesive (refractive index> 1.5) so as to sandwich the thin film magnetic head element 5, and thereafter The joined first and second blocks 6a and 6b are configured to have a predetermined plate thickness t1 by surface polishing. The thin film magnetic head element 5 is configured as a recording head or a recording / reproducing head.

  The lens main body (so-called pseudo hemispherical lens) 3L is positioned on the light-transmitting substrate 3S having the thin-film magnetic head element 5 after the ball lens is planarly polished to form a lens surface substantially orthogonal to the optical axis OO. , And bonded and integrated through an optical adhesive.

  The thin film magnetic head element 5 is formed so as to be sandwiched between the first and second blocks 6a and 6b, and then depth polished (planar polishing) with respect to the head forming surface. After that, the first and second blocks 6a and 6b are bottom-polished to have a plate thickness of a predetermined thickness t1, and the light transmissive substrate 3S having the thin film magnetic head element 5 is formed. On the other hand, the lens body 3L whose bottom surface is polished is positioned and fixed on the light-transmitting substrate 3S. The structure body in which the lens body 3L and the light transmissive substrate 3S are joined has the same overall height T as the radius R of the hemisphere / super hemisphere lens, and is optically equivalent to the hemisphere / super hemisphere lens. It is. That is, the light collected by the upper objective lens 2 is focused on the bottom surface of the synthesized hemisphere / super hemisphere lens 3 (the surface facing the magnetic recording medium 11), that is, the bottom surface of the light transmissive substrate 3S. It functions as a hemisphere / super hemisphere lens.

With the single objective lens 2, the diameter of the focused spot can be reduced only by λ / NA due to the diffraction limit of light. λ is the wavelength λ of the light used, and NA is the numerical aperture of the objective lens. By the way, in the hemisphere / super hemisphere lens system, the spot diameter can be reduced to 1 / n (hemisphere lens) and 1 / n ² (super hemisphere lens) on the bottom surface (ie, focal plane) of the hemisphere / super hemisphere lens. n is the refractive index of the hemisphere / super hemisphere lens. By narrowing the gap g1 between the lens surface and the magnetic recording medium to λ / 10 or less, 1 / n (hemispherical lens) and 1 / n ² (on the surface of the magnetic recording medium 11 are formed on the surface of the magnetic recording medium 11 by the imaging action by the near light field. It is possible to form a spot diameter of a super hemispherical lens.

  In the present embodiment, the light transmissive substrate 3S, which is a constituent element of the hemisphere / super hemisphere lens 3, is formed so as to extend outward from the lens body (pseudo hemisphere lens) 3L integrated thereon. Is done. Further, the light-transmitting substrate 3S has a bottom surface on the side facing the magnetic recording medium 11, that is, a facing surface, leaving a central region where the thin-film magnetic head element 5 is formed and moving toward the periphery of the magnetic recording medium. It is formed as a stepped surface shape that has two steps, d1 and d2, so as to move away from the surface. That is, on the surface of the light-transmitting substrate 3S facing the magnetic recording medium 11, the central region facing the thin film magnetic head element 5 protrudes, and has two steps d1 and d2 from the protruding portion 7 toward the periphery. The shape is set back.

  In this case, the first step d1 is a shallow step, and the second step d2 is set deeper than the first step d1. The conditions of the two steps d1 and d2 will be described in detail later.

  As shown in FIG. 2, the objective lens 2 is disposed on the light transmissive substrate 3 </ b> S via an annular spacer 9. In this example, the light-transmitting substrate 3S has a length L on one side extending outside the outer diameter of the annular spacer 9 and a length W on the other side perpendicular to the annular spacer 9 is an annular spacer 9. It is formed so as to have substantially the same length as the outer diameter. At the same time as the magnetic head coil of the thin film magnetic head element 5, an extension portion extending outside the lens body (pseudo hemispherical lens) 3 </ b> L of the light-transmitting substrate 3 </ b> S, that is, an extension portion 10 extending outward from the spacer 9 in FIG. The formed terminal lead-out wiring 12 is led out, and an electrode pad (so-called bonding pad) 13 is formed at the end thereof.

  The surface on which the electrode pad 13 is formed is a surface along the end surface of the first block 6a on which the thin film magnetic head element 5 of the light transmissive substrate 3S is formed. In this case, the light transmissive substrate 3S is formed by joining the first and second blocks 6a and 6b, but the second block 6b is partially cut away so that the electrode pad 13 faces the outside.

  As the magnetic recording medium 11, for example, a magnetic recording medium having various configurations such as a magnetic tape or a magnetic disk can be used. This magnetic recording medium 11 is formed by sequentially forming a soft magnetic layer 16 and a recording layer 17 of a magnetic layer having a required coercive force on a non-magnetic substrate 15 such as a film or disk.

  The length L on the long side of the light transmissive substrate 3S is determined by the diameter of the objective lens 2 and the clearance space required during wire bonding. The bonding clearance can be, for example, about 1 mm on one side. When the diameter of the objective lens 2 is about 3 mm to 4 mm, the length L on the long side of the light-transmitting substrate 3S is about 5 mm to 6 mm. can do. Since the objective lens 2 is formed by a glass molding process, it is practically difficult to mold a lens having a diameter of less than about 1 mm. Accordingly, the lower limit of the length L of the light transmissive substrate 3S is about 1 mm to 2 mm. That is, the length L of the light transmissive substrate 3S can be about 2 mm to 6 mm.

  Next, with reference to FIG. 3, a description will be given of the two-step steps d1 and d2 and the condition of the length r1 from the optical axis to the terrace end of the first step. In FIG. 3, θ1 is an angle formed by the first step terrace surface 32 and a line connecting the end E2 and a point on the optical axis OO of the surface of the magnetic recording medium 11, and θ2 is the second step terrace surface. 33 and an angle formed by a line connecting the end (that is, the end of the light transmissive substrate 3S) E3 and a point on the optical axis OO of the surface of the magnetic recording medium 11, r1 is the optical axis of the light transmissive substrate 3S. The distance from the center on OO to the end E2 of the first step terrace surface 32, r2 is from the center on the optical axis OO of the light transmissive substrate 3S to the end E3 of the second step terrace surface 33. This is the distance (that is, the distance from the center to the end of the light transmissive substrate 3S).

  The depth d1 of the first step is a so-called unobstructed shallowness in which the light 30 incident from the objective lens 2 having a required numerical aperture is not partially shielded by the bottom edge E1 of the first stepped portion. In addition, the first step terrace surface 32 is set to a shallow depth so that dust does not collect during operation. If dust or dust accumulates on the terrace surface 32, the surface of the projection 7 facing the thin film magnetic head element 5 is damaged by the dust and dust.

  The depth d2 of the second step is set deeper than the depth d1 of the first step, and when the optically assisted magnetic head 1 and the magnetic recording medium 11 are relatively inclined, the light transmissive substrate. The depth is set such that the first step terrace end E2 does not come into contact with the magnetic recording medium 11 before the 3S end E3. The depth d2 of the second step is also related to the distance r1 from the center to the first step terrace end E2.

r1 is set by the following equation.
θ1 ≧ θ2
r1 ≦ (d1 × r2) / (d1 + d2)

  d1, d2, and r1 are determined by the allowable tilt angle, the length r2 of the light transmissive substrate 3S, the numerical aperture NA of the objective lens 2, and the like. It is preferable to set in such a range.

  In the present embodiment, the allowable relative tilt angle between the optically assisted magnetic head 1 and the magnetic recording medium 11 can be set to 0.5 degrees or less, preferably 0.3 degrees or less. The length r2 of the light transmissive substrate is 1.0 mm to 3.0 mm, the depth d1 of the first step is 8 μm or less, preferably 4 μm to 8 μm, and the depth d2 of the second step is the first step. Deeper than the depth d1, the total d1 + d2 of the first step d1 and the second step d2 can be 15 μm or more, preferably 15 μm to 25 μm. If the depth d1 of the first step is smaller than 4 μm, it is easily affected by dust and the like, and if it is deeper than 8 μm, the incident light may be blocked. 15 μm of the total step (d1 + d2) corresponds to an inclination angle of 0.3 degrees, and 25 μm corresponds to an inclination angle of 0.5 degrees.

  As a specific example, the thickness t1 of the light transmissive substrate 3S is 200 μm, the thickness r2 of the lens body 3L is 300 μm, the total t1 + t is 500 μm, and the length r2 from the center to the end of the light transmissive substrate 3S (= L / 2) is 3.0 mm and the allowable relative tilt angle is 0.3 degree, the first step d1 is 6.0 μm, the second step d2 is 9.0 μm, and the sum of the steps (d1 + d2) ) 15 μm. In this case, the diameter of the protruding portion 7 in the central region is 50 μm ± 5 μm, and the distance (diameter) r1 from the center to the first step terrace end E2 is smaller than 1.2 mm (r1 <1.2 mm), for example, 700 μm ± It can be 50 μm.

  In the present embodiment, the allowable range of the relative tilt angle between the optically assisted magnetic head 1 and the magnetic recording medium 11 (corresponding to the allowable value of the angle θ3 in FIG. 6) is 0.5 degrees or less, preferably 0. The grounds for 3 degrees or less are as follows. This tilt angle is determined in consideration of wavefront aberration due to the relative tilt of the optical system with respect to the light source and the tilt of the surface of the magnetic recording medium itself such as warpage. FIG. 4 shows a two-group condenser lens system 4 having an effective numerical aperture NA = 1.56 when the radius R of the hemisphere / super hemisphere lens 3 is 0.5 mm. The case where the incident angles are slightly different is indicated by the light beams of solid line a and broken line b. FIG. 5 shows the wavefront aberration characteristics depending on the inclination of the incident angle of light in the two-group condenser lens system 4. In FIG. 5, the horizontal axis represents the inclination of the incident angle [°] of light corresponding to the inclination of the magnetic recording medium, and the vertical axis represents the amount of wavefront aberration [mλ] generated by the inclination of the incident angle.

  When the allowable aberration is 30 mλ, the allowable incident angle is about 0.4 °. That is, the tilt of the optical system that falls within the 30 mλ aberration is 0.4 °. On the other hand, a tilt (angle) due to a warp of a magnetic recording medium using magnetic recording utilizing near-field light, for example, the magnetic disk itself, does not directly affect the optical characteristics. If it is assumed that a glass substrate is used as the magnetic disk, the tilt (angle) of the glass disk can be made 0.1 ° or less. For this reason, as the relative tilt angle (tilt) between the optically assisted magnetic head and the magnetic recording medium, the allowable tilt angle is equal to 0.5% of the tilt amount of the optical component and the tilt amount of the glass disk. It can be below.

Here, since there are other factors that give aberration, it is generally set to about half of the limit to allow for a single cause. In this case, the allowable amount of the tilt angle of the optical system is 0.2 ° or less. For this reason, the allowable relative tilt angle (tilt) is 0.3 ° or less when the tilt amount 0.2 ° of the optical system and the tilt amount 0.1 of the glass disk are combined. Is preferred.
Therefore, in order to obtain the shape of the optically assisted magnetic head that does not contact the magnetic recording medium 11 even with an inclination of 0.5 ° or less, preferably 0.3 ° or less, in the present embodiment, The surface of the light transmissive substrate 3S facing the magnetic disk was formed in a two-step surface.

  According to the optically assisted magnetic head 1 according to the present embodiment, by configuring the hemisphere / super hemisphere lens 3 in which the light transmissive substrate 3S is extended outside the lens main body (pseudo hemispherical lens) 3L, the light transmissive substrate 3S is constructed. The electrode pad 13 of the thin film magnetic head element 5 can be formed on the surface of the extension 10 of the substrate 3S, and a practical optically assisted magnetic head can be provided.

  Moreover, the surface of the light-transmitting substrate 3S facing the magnetic recording medium 11 is directed away from the magnetic recording medium, for example, the disk medium, toward the periphery, leaving the central region (projecting portion) 7 having the thin film magnetic head element 5. By adopting a shape having two steps d1 and d2, the optically assisted magnetic head 1 and the magnetic recording medium 11 are caused by the relative inclination between the optically assisted magnetic head 1 and the magnetic recording medium 11. Contact can be avoided. In addition, since the first step d1 is formed shallowly, the incident light 30 passes through the objective lens 2 and the hemisphere / super hemisphere lens 3 and is collected at the central portion of the bottom surface of the hemisphere / super hemisphere lens 3. A part of 30 is not shielded.

  Further, by forming two steps d1 and d2, making the first step d1 shallow and making the second step deep, the total step is in contact with the magnetic recording medium at the second step d2. Can not be deep. In addition, the first step d1 can be made shallow, which makes it difficult for dust and dirt to accumulate in the step d1, and the optically assisted magnetic head 1 moves at a relatively high speed with respect to the magnetic recording medium 11. Damage to the surface of the protrusion 7 due to dust and dirt can be mitigated.

  Further, the superiority of the present embodiment will be described by comparing the present embodiment with a reference example. FIG. 6 shows the configuration of the optically assisted magnetic head 41 of Reference Example 2. First, as an optically assisted magnetic head, consider the configuration of the optically assisted magnetic head having a flat bottom surface without providing a step on the bottom surface of the light-transmitting substrate in the configuration of the present embodiment. In the case of the optically assisted magnetic head of Reference Example 1, when the optically assisted magnetic head and the magnetic recording medium are relatively inclined, they may come into contact with each other and may be damaged.

  On the other hand, as shown in FIG. 7A, a hemisphere / super hemisphere lens 52 is formed by the lens body 52L and the light transmissive substrate 52S, and the surface of the light transmissive substrate 52S facing the magnetic recording medium is left leaving the central region. There has been proposed an optically assisted magnetic head having a two-stage condensing lens system including a hemispherical / super hemispherical lens 52 and an objective lens (not shown) provided with one step toward the periphery. Further, as shown in FIG. 7B, a hemisphere / super hemisphere lens 52 is formed by the lens body 52L and the light-transmitting substrate 52S, and the surface of the light-transmitting substrate 52S facing the magnetic recording medium is changed from the central portion to the periphery. There has also been proposed an optically assisted magnetic head formed so as to gradually recede in a conical shape and having a two-group condensing lens system of the hemisphere / super hemisphere lens 52 and an objective lens (not shown).

  For example, in the case of considering the optically assisted magnetic head 41 of Reference Example 2 shown in FIG. 6 to which the facing surface shape of the light transmissive substrate of FIG. 7 is applied (FIG. 6 schematically shows, The objective lens is omitted), which is disadvantageous compared to the optically assisted magnetic head having the hemispherical / super hemispherical lens 52 of FIGS. 7A and 7B for the following reason. As shown in FIG. 6, for example, the length r2 from the center to the end of the light-transmitting substrate 3S is 3.0 mm, the depth of one step (projection height) d3 is 15 μm, and the optically assisted magnetic The flying distance of the head 41 from the magnetic recording medium 11 is set to 20 nm. Even when the step d3 having the same depth is provided on the light-transmitting substrate 3S of the light-assisted magnetic head of Reference Example 2 in FIG. Since the substrate 3S is long, it is easier to contact the magnetic recording medium 11 than the optically assisted magnetic head of FIG. 7A.

In FIG. 6, when an inclination angle (tilt) θ3 when the optically assisted magnetic head 41 contacts the magnetic recording medium 11 is obtained,
θ3 = d3 / r2 = 15 μm / 3 mm = 5 mrad = 0.29 deg

  Assuming that the tilt angle θ3 allowable as the relative tilt between the optically assisted magnetic head 41 of Reference Example 2 and the magnetic recording medium 11 having the light transmissive substrate 3S having the length r2 of 6 mm shown in FIG. The step d3 for preventing contact with an inclination of up to 0.3 degrees is 15.7 μm. Therefore, in the case of the optically assisted magnetic head 41 of the reference example, it is only necessary to form a deep step d3. However, when a near-field optical system is formed by combining an objective lens and a hemisphere / super hemisphere lens, light transmission is possible. There is a possibility that a part of incident light condensed on the central portion of the surface of the conductive substrate 3S facing the magnetic recording medium 11 is shielded.

That is, in FIG. 8, the step d3 is obtained when the near-field optical system is a combination of the objective lens having a numerical aperture of 0.75 and the hemisphere / super hemisphere lens 3. Here, the diameter S1 of the protruding portion on which the central thin film magnetic head element is formed is 50 μm. The incident angle θ4 of incident light collected through an objective lens having a numerical aperture of 0.75 is
θ4 = sin ⁻¹ (0.75) = 48.59 deg
d3 = S1 / 2 × tan (90−θ4)
= 25 × tan (90−θ4)
= 22.04deg
It becomes.

  As described above, the step d3 of the one-stage structure with which the incident light 30 is in contact is about 22 μm, and if it exceeds 22 μm, a part of the incident light collected at the center is blocked. Considering the existence of a slight tilt of the optically assisted magnetic head, the lens body (pseudo hemispherical lens) 3L has a step of 15 μm that can handle a tilt angle θ3 of 0.3 degrees. When manufacturing errors such as a shift between the center and the center of the light-transmitting substrate 3S are taken into account, there is a large risk that a part of incident light is shielded, which is not practical.

  On the other hand, in the present embodiment, when the numerical aperture NA of the objective lens 2 is 0.75 and the diameter S1 of the protruding portion 7 on the bottom surface of the light-transmitting substrate 3S is 50 μm, the first shown in FIG. The first step d1 is shallowened to 8 μm or less, for example, 6 μm, and the second step d2 formed by leaving the distance (diameter) r1 = 700 μm from the center to the second step terrace end E2 is deepened to obtain a total step Is configured to ensure 15 μm or more. In this way, the two-step step structure prevents the incident light 30 collected at the center from being shielded (see FIG. 8).

Next, an embodiment of a method for manufacturing the optically assisted magnetic head of the present embodiment will be described with reference to FIGS.
First, as shown in FIG. 10, a first block 6a and a second block 6b made of the same optical material as the light transmissive substrate 3S are provided. As shown in FIG. 9, the joint end face 6a1 of the first block 6a is preliminarily formed of a thin film magnetic film composed of a main magnetic pole 21, a sub magnetic pole 22, a lower layer thin film magnetic head coil wire element 23A, and an upper layer thin film magnetic head coil wire element 23B. A thin film magnetic head element (here, a recording thin film magnetic head element) 5 having a head coil 23 is formed. The thin film magnetic head coil 23 is integrally formed with a terminal lead-out wiring 12 so as to extend from the terminal, and an electrode pad (so-called bonding pad) 13 shown in FIG.

  Next, as shown in FIG. 11, the joining end surfaces 6a1 and 6b1 of the first block 6a and the second block 6b are abutted and joined via an optical adhesive so as to sandwich the thin film magnetic head element 5. Thereafter, the block bonded body is planarly polished to a position where a predetermined gap depth D is left so that the front end side of the thin film magnetic head element 5 faces, thereby obtaining a light-transmitting substrate 3S having the thin film magnetic head element. The light-transmitting substrate 3S has a thin film magnetic head element 5 in the center and is formed in a required size, for example, 6 mm × 4 mm. The first block 6a is formed in a size of 6 mm × 2 mm, and the second block 6b is formed in a size of 4 mm × 2 mm so that the electrode pad 13 faces the outside.

  Next, although not shown, a pseudo hemispherical lens, which is a lens body 3L, is bonded to the light transmissive substrate 3S via an optical adhesive.

  Then, as shown in FIG. 12A, the first photoresist film 24A, which is a positive type in this example, is formed on the bottom surface of the light-transmitting substrate 3S to which the lens body 3L is integrally bonded, that is, on the opposite surface facing the magnetic recording medium. A photoresist film is formed, and exposure is performed by irradiating the required light 26 through the first photomask 25. In this exposure process, a portion other than the central region of the required area having the thin-film magnetic head element 5, in this example, the portion corresponding to the circular region having a diameter of 50 μm ± 5 μm is exposed.

  Next, as shown in FIG. 12B, development processing is performed to form a first resist mask 27 in the central region of the bottom surface of the light transmissive substrate 3S. Next, the bottom surface of the light transmissive substrate 3S is selectively removed by etching through the first resist mask 27 to form a first step d1 having a required depth. For example, the first step d1 having a depth of 6 μm is formed.

  Next, as shown in FIG. 12C, a second photoresist film 24B, in this example, a positive photoresist film is formed again on the bottom surface of the light-transmitting substrate 3S, and the second photomask 28 is interposed therebetween. Then, exposure is performed by irradiating the required light 26. In this exposure process, a central region of a required area including a part of the first step d1, that is, a portion corresponding to a circular region having a diameter of 700 μm ± 50 μm from the center is exposed in this example.

  Next, as shown in FIG. 12D, development processing is performed to form a second resist mask 29 on the bottom surface of the light-transmitting substrate 3S. Next, the bottom surface of the light-transmitting substrate 3S is selectively etched through the second resist mask 29 to form a second step d2 deeper than the first step d1. For example, the second step d2 is formed so as to have a depth of 12 μm from the first step d1, and thus a total depth of 18 μm.

  In this way, as shown in FIG. 12E, the hemisphere / super hemisphere lens 3 is formed. Next, although not shown, the objective lens 2 is joined to the hemisphere / super hemisphere lens 3 via the spacer 9 to obtain the target optically assisted magnetic head 1 (see FIG. 2).

  The thin-film magnetic head element 5 can be formed by stacking a recording magnetic head and a reproducing head made of, for example, a magnetoresistive element (MR element) when a recording / reproducing magnetic head element is used.

FIG. 13 is a schematic configuration diagram showing an embodiment of a magnetic recording apparatus having an optically assisted magnetic head according to the present invention.
In the magnetic recording device 61 of the present embodiment, a light source unit, for example, a light source unit 62 having a semiconductor laser element with a wavelength of 400 nm, an optically assisted magnetic head 1 according to the present invention, and a magnetic disk as a magnetic recording medium 11 are arranged. The recording signal power supply unit for supplying a recording signal to the arrangement unit 64 of the magnetic recording medium 11 that is rotated and driven, and the magnetic head coil of the thin film magnetic head element 5 (not shown) of the optically assisted magnetic head 1, that is, recording The laser light from the signal circuit 65 and the light source unit 62 is introduced into the optically assisted magnetic head 1, and the reflected light (returned light) from the magnetic recording medium 11 is detected, for example, to a light detection means 66 having a photodiode. And an optical system 67 to be introduced.

  The magnetic recording medium 11 is configured by sequentially laminating a soft magnetic layer 16 and a recording layer 17 on a glass substrate 15.

  The optical system 67 includes, for example, a cotometer lens (not shown), a beam splitter 68, and the like. Further, a detection output detected by the light detecting means 66 is calculated to obtain a desired servo signal for the optically assisted magnetic head 1, for example, each servo signal such as focusing and tracking, and a positioning control device 69 for performing these controls is provided. Have. When the optically assisted magnetic head 1 is mounted with a reproducing thin film magnetic head in addition to the thin film magnetic recording head, the head element is connected to a reproducing signal circuit and performs a magnetic signal reproducing operation, although not shown.

  The magnetic recording medium placement unit 64 is driven to rotate by a spindle motor 70 in a state where the magnetic recording medium 11, for example, a magnetic disk is placed. The positioning control device can be constituted by, for example, a biaxial actuator. The biaxial actuator is equipped with the optically assisted magnetic head 1 according to the present invention having a two-group condensing lens system 4 and is driven based on a tracking servo signal, a focus servo signal, and a gap servo signal, and the two-group condensing lens system 4 is driven. The movement is adjusted in the tracking direction, and the movement is adjusted in the optical axis direction, that is, the focus direction.

  In the magnetic recording device 61 of the present embodiment, the magnetic recording medium 11 is rotated, and a laser beam having a required wavelength, in this example, 400 nm, is emitted from the light source unit 62 along the optical axis of the optically assisted magnetic head 1 by the optical system 67. The near-field light from the optically assisted magnetic head 1 is irradiated onto the magnetic recording medium 11. The optically assisted magnetic head 1 can have a numerical aperture NA of 1.0 or more by the two-group condensing lens 4 including the objective lens 2 and the hemisphere / super hemisphere lens 3, and is on the magnetic recording medium 11 by near-field light. The spot becomes very small.

  The spot is irradiated onto the rotating magnetic recording medium 11 and at the same time an information recording signal is supplied to the magnetic head coil of the thin film magnetic head element 5 to record from the tip of the main magnetic pole of the thin film magnetic head element 5. A signal magnetic field is applied to the magnetic recording medium 11 to record a signal.

  According to the magnetic recording device 61 of the present embodiment, the surface facing the magnetic recording medium 11 of the optically assisted magnetic head 1 has two steps toward the periphery, leaving the central region where the thin film magnetic head element 5 faces. Since the shape retreats at d1 and d2, contact between the optically assisted magnetic head 1 and the magnetic recording medium 11 due to relative inclination during operation can be avoided. Therefore, stable gap control can be performed as the gap control between the optically assisted magnetic head 1 and the magnetic recording medium 11, and a highly reliable magnetic recording apparatus for practical use can be provided.

  Next, an experimental result confirming the effect of providing two steps on the bottom surface of the above-described light-transmitting substrate will be described. An optically assisted magnetic head according to the present invention having two steps with a total step of 18 μm is formed, and the bottom surface of the optically assisted magnetic head 1 and a magnetic recording medium (here, magnetic recording medium) are formed by the magnetic recording apparatus 61 shown in FIG. Gap servo characteristics for maintaining the distance between the surface of the disk (11) and the surface of 11 at 10 nm were measured. For comparison, the same measurement was performed for the optically assisted magnetic head of the comparative example in which only one step with a step of 6 μm was applied and the other configurations were the same as those with two steps. It was.

  In these experiments, since the magnetic recording is not performed, the configuration not including the recording head is used. However, the contact between the optically assisted magnetic head and the magnetic disk, which is the purpose of the experiment, includes the recording head. We thought it was equivalent to the configuration. In the experiment, the magnetic recording medium (magnetic disk) 11 was kept stationary without rotating.

  The results are shown in FIG. FIG. 14 shows gain (dB) and phase (deg) on the vertical axis and frequency (Hz) on the horizontal axis. Graph Ia is a gain curve when two steps are applied, and graph Ib is a phase curve when two steps are applied. Graph IIa is a gain curve when there is only one step, and IIb is a phase curve when there is only one step. In the case of a one-step step having a total step of 6 μm, as shown in graphs IIa and IIb, changes in gain and phase are observed in the frequency region of several kHz, which is considered to be due to contact. On the other hand, in the case of two steps with a total step of 18 μm, as shown in graphs Ia and Ib, it is confirmed that the frequency response of gain and phase is smooth and no contact occurs.

  Thus, by providing two steps, contact between the optically assisted magnetic head and the magnetic disk can be avoided, and stable gap control can be realized.

1 is a schematic configuration showing an embodiment of an optically assisted magnetic head according to the present invention. 1 is a partially broken perspective view showing an embodiment of an optically assisted magnetic head according to the present invention. It is a schematic sectional drawing with which it uses for description of the two steps of this invention. It is a schematic block diagram of the 2 group condensing lens system used for description of this invention. FIG. 5 is a characteristic diagram showing wavefront aberration characteristics depending on a light incident angle using the two-group condensing lens system of FIG. 4. It is a typical block diagram of the optically assisted magnetic head which concerns on the reference example used for a comparison with this Embodiment. A, B It is a block diagram which shows the example of the conventional hemisphere / super hemisphere lens with which it uses for the comparison description of this Embodiment and a reference example. It is a diagram with which it uses for the comparison description of this Embodiment and a reference example. It is a block diagram of the thin film magnetic head element which shows one Embodiment of the manufacturing method of the optically assisted magnetic head which concerns on this invention. FIG. 6 is a manufacturing process diagram (part 1) illustrating an embodiment of a method for manufacturing an optically assisted magnetic head according to the present invention; FIG. 6 is a manufacturing process diagram (part 2) illustrating the embodiment of the method for manufacturing the optically assisted magnetic head according to the present invention; A to E are manufacturing process diagrams (part 3) illustrating an embodiment of the method for manufacturing the optically assisted magnetic head according to the present invention. 1 is a schematic configuration diagram showing an embodiment of a magnetic recording apparatus according to the present invention. It is a graph which shows the frequency characteristic of the gain and phase which compared this invention and the reference example.

Explanation of symbols

  1 .. Optically assisted magnetic head 2 .... Objective lens 3 .... Hemisphere / super hemisphere lens 3L ... Lens body (pseudo-hemisphere lens) 3S ... Light transmissive substrate, d1, d2, ... 2 stages 5 ..Thin film magnetic head element, 6a, 6b ..First and second blocks 7, ..projection, g1 ..gap, 11 ..magnetic recording medium, 12..terminal lead-out wiring, 13. · Electrode pads, 15 · · Substrate, 16 · · Soft magnetic layer, 17 · · Recording layer, 24A, 24B · · Photoresist film, 25, 28 · · Photomask, 26 · · Light for exposure, 30 · · · Incident light, 61... Magnetic recording device, 62... Light source, 64.

Claims (6)

A two-group condenser lens system having an objective lens, a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element;
The hemispherical lens or super hemispherical lens is composed of a combination of a lens body constituting a spherical lens and a light-transmitting substrate disposed on the side facing the magnetic recording medium,
The light transmissive substrate is formed to extend outward from the lens body,
A thin film magnetic head element is formed on the light transmissive substrate,
The surface of the light transmissive substrate facing the magnetic recording medium has a two-step difference so as to leave the magnetic recording medium toward the periphery, leaving a central region where the thin film magnetic head element is formed. An optically assisted magnetic head characterized by being retracted. Of the two steps, the first step is set to a shallow step that does not block incident light,
The optically assisted magnetic head according to claim 1, wherein the second step is set to be deeper than the first step. The first step is d1, the radius from the center of the light transparent substrate to the end of the first step is r1, the second step is d2, and the maximum length of the hemispherical lens or super hemispherical lens is r2. When
r1 ≦ (d1 × r2) / (d1 + d2)
The optically assisted magnetic head according to claim 2, wherein the following formula is satisfied. 2. The light assist type according to claim 1, wherein an electrode pad connected to a terminal lead-out wiring of the thin film magnetic head element is formed on an extension portion extending outward from the lens body of the light transmissive substrate. Magnetic head. An optically assisted magnetic head manufacturing method comprising an objective lens, a two-group condensing lens system having a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element,
Forming a lens body constituting the spherical lens portion of the hemispherical lens or super hemispherical lens;
A bonding step in which a thin film magnetic head element is disposed on a surface of the lens body facing the magnetic recording medium, and a light-transmitting substrate having an extended portion extending outward from the lens body;
A first step forming step for forming a first step on a surface of the light transmissive substrate facing the magnetic recording medium, leaving a central region where the thin film magnetic head element is formed;
A second step is formed on the surface of the light transmissive substrate facing the magnetic recording medium, leaving a central region where the thin film magnetic head element is formed and a part of the first step. A method of manufacturing a light-assisted magnetic head. A light source unit;
A magnetic recording medium placement section;
An optically assisted magnetic head;
A recording signal power supply unit;
An optical system that forms an optical path that guides light from the light source unit to the light-assisted magnetic head;
The optically assisted magnetic head includes an objective lens, a two-group condensing lens system having a hemispherical lens or a super hemispherical lens, and a thin film magnetic head element.
The hemispherical lens or super hemispherical lens is composed of a combination of a lens body constituting a spherical lens and a light-transmitting substrate disposed on the side facing the magnetic recording medium,
The light transmissive substrate is formed to extend outward from the lens body,
A thin film magnetic head element is formed on the light transmissive substrate,
The surface of the light transmissive substrate facing the magnetic recording medium has a two-step difference so as to leave the magnetic recording medium toward the periphery, leaving a central region where the thin film magnetic head element is formed. A magnetic recording device, wherein the magnetic recording device is retracted.

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