JP2008165852A - Thin film magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film magnetic head high in heater thermal efficiency. <P>SOLUTION: This thin film magnetic head is provided with: a reproducing element formed on an undercoat film of a head substrate surface; a recording element formed on a layer above the reproduction element; and a heater formed between the reproducing and recording elements and energized to generate heat, thereby projecting at least one of the reproducing and recording elements to the recording medium side by thermal expansion. A heat dissipation suppression layer lower in heat conductivity than the undercoat film is positioned in an area overlapping at least the reproducing element and the heater in a stacking direction in the undercoat film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin film magnetic head that controls the flying height by locally projecting an element portion toward a recording medium by thermal expansion.

A thin film magnetic head uses a magnetoresistive effect to read out magnetic information from a recording medium and a recording element that is stacked on the reproducing element and records the magnetic information by applying a recording magnetic field to the recording medium. And an element. As is well known, the reproducing element is formed between the lower shield layer and the upper shield layer via a gap layer. For example, in the perpendicular recording system, the recording element has a magnetic gap layer on the surface facing the recording medium. The main magnetic pole layer, the return yoke layer, and the recording coil that applies a recording magnetic field to the main magnetic pole layer are exposed. In recent years, a heater that generates heat when energized is provided in the vicinity of the element, and the element part protrudes toward the recording medium side by thermal expansion, so that the distance between the element part and the recording medium is locally narrowed. There is something that improves. A thin film magnetic head provided with such a heater is described in Patent Documents 1 and 2, for example.
Japanese Patent Laid-Open No. 2004-199797 JP 2006-107656 A

  In the conventional thin film magnetic head having a heater, the reproducing recording performance is improved as the facing distance between the element portion and the recording medium is reduced. Therefore, the heater thermal efficiency (the total amount of heat generated from the heater and the amount of heat transmitted to the element portion). The challenge is how to increase the ratio).

  An object of the present invention is to obtain a thin film magnetic head having high heater thermal efficiency.

  The present invention pays attention to the fact that the heat of the heater escapes from the element part to the outside through the head substrate, suppresses heat radiation from the head substrate, increases the amount of heat to the element part, and increases the heat efficiency of the heater. I suggest that.

  That is, the present invention is a reproducing element formed on the undercoat film on the surface of the head substrate, a recording element formed above the reproducing element, and formed between the reproducing element and the recording element, and generates heat when energized. Then, in the thin film magnetic head provided with a heater for projecting at least one of the reproducing element and the recording element to the recording medium side by thermal expansion, the reproducing element and the heater are positioned in a region overlapping with the reproducing element and the heater in the stacking direction. In addition, a heat dissipation suppression layer having a lower thermal conductivity than the undercoat film is provided.

  By providing the heat dissipation suppression layer, heat transferred from the heater and the element portion to the head substrate side can be kept between the heater and the heat dissipation suppression layer, and heat dissipation from the head substrate can be suppressed. it can. As a result, compared to the case where only the undercoat film is formed on the head substrate surface, the amount of heat applied to the element portion (the amount of heat contributing to the protrusion of the element portion) is increased, and the heater thermal efficiency is improved. In particular, since the reproducing element is sandwiched between the heater and the heat dissipation suppressing layer in the stacking direction, heat from the heater can be concentrated on the element portion.

The heat conductivity of the heat dissipation suppressing layer is preferably 1/10 or less of the heat conductivity of the undercoat film. Actually, the undercoat film is made of Al ₂ O ₃ and the heat dissipation suppressing layer is made of SiO ₂ .

  The heat dissipation suppressing layer preferably has a larger area than at least the element areas of the reproducing element and the recording element. The larger the planar size of the heat dissipation suppressing layer, the more heat can be retained in the heat dissipation suppressing layer.

  The heat dissipation suppressing layer is preferably formed so as to recede from the surface facing the recording medium to the back side in the height direction. According to this aspect, it is possible to avoid problems such as local indentation and smearing due to a difference in polishing processing rate with the undercoat film during polishing processing for forming a surface facing the recording medium.

  According to the present invention, since the heat transmitted from the heater and the element unit to the head substrate side is retained by the heat dissipation suppression layer, the amount of heat applied to the element unit increases, and a thin film magnetic head with high heater thermal efficiency can be obtained.

  The present invention will be described below with reference to the drawings. In each figure, the X direction is defined by the track width direction, the Y direction is defined by the height direction, and the Z direction is defined by the stacking direction of each layer constituting the thin film magnetic head and the moving direction of the recording medium.

  FIG. 1 is a longitudinal sectional view showing the structure of the thin-film magnetic head H1 according to the first embodiment of the present invention, cut at the center of the element. The thin film magnetic head H1 is a perpendicular magnetic head having a reproducing element R and a recording element W formed by laminating thin films on a slider (head substrate) 1. The reproducing element R reads magnetic information from the recording medium M using the magnetoresistive effect, and the recording element W magnetizes the hard film Ma of the recording medium M in the vertical direction by applying a perpendicular recording magnetic field Φ to the recording medium M. Recording operation.

The recording medium M has a hard film Ma with high residual magnetization on the medium surface side and a soft film Mb with high magnetic permeability on the inner side of the hard film Ma. The recording medium M has a disk shape, for example, and is rotated around the center of the disk as the rotation axis. The slider 1 is made of Al ₂ O ₃ .TiC. One end face 1a of the slider 1 faces the recording medium M. When the recording medium M rotates, the slider 1 is moved from the surface of the recording medium M by the air flow on the surface. Surface.

An undercoat film 2 made of Al ₂ O ₃ is formed on the trailing side end face 1 b of the slider 1, and a reproducing element R is laminated on the undercoat film 2. The reproducing element R includes a lower shield layer 11, an upper shield layer 13, a gap insulating layer 14 that fills the space between the lower shield layer 11 and the upper shield layer 13, and a multilayer film 12 that is positioned in the gap insulating layer 14. have. The multilayer film 12 is a magnetoresistive effect element such as AMR, GMR, or TMR.

The recording element W is laminated on the upper shield layer 13 via the separation layer 20, and is a main magnetic pole made of a ferromagnetic material having a high saturation magnetic flux density such as Ni—Fe, Co—Fe, Ni—Fe—Co. Al ₂ O ₃ , SiO ₂ , Au, Ru, etc. interposed between the main magnetic pole layer 34 and the return yoke layer 40 on the facing surface (medium facing surface) F of the layer 34 and the return yoke layer 40 and the recording medium M A magnetic gap layer 35 made of a nonmagnetic material, coil layers (31, 37) for applying a recording magnetic field to the main magnetic pole layer 34, and a magnetic material having a saturation magnetic flux density lower than that of the main magnetic pole layer 34. There is an auxiliary yoke layer 33 formed immediately below, and a height determining layer 39 formed on the magnetic gap layer 35 by retreating a predetermined distance from the medium facing surface F.

In the main magnetic pole layer 34, the dimension in the X direction shown in the drawing of the front end surface exposed to the medium facing surface F is defined by the write track width, and the return yoke layer 40 is a predetermined end surface 40a exposed to the medium facing surface F. The main magnetic pole layer 34 is opposed to the main magnetic pole layer 34 with an interval (gap interval), and is connected to the main magnetic pole layer 34 at a connecting portion 40b located on the far side in the height direction from the tip end surface 40a. The return yoke layer 40 is formed with dimensions larger than the main magnetic pole layer 34 in the track width direction and the height direction. Insulating layers 41 and 42 made of, for example, Al ₂ O ₃ , SiO ₂ , Al—Si—O or the like are formed around the main magnetic pole layer 34 and the auxiliary yoke layer 33.

A lower coil 31 laminated on the upper shield layer 13 via a coil insulating underlayer 30 and an upper coil 37 laminated on the magnetic gap layer 35 via a coil insulating underlayer 36 are composed of a plurality of coil wires extending in the track width direction. Are arranged in a plurality of rows in the height direction, and the ends of the coil wires are connected to each other to form a solenoid coil wound around the upper and lower layers of the main magnetic pole layer 34 and the auxiliary yoke layer 33. Each coil wire of the lower layer coil 31 and the upper layer coil 37 is, for example, one or more selected from Au, Cu, Al, Pt, Ag, W, Ni, NiP, Rh, Fe, Co, Cr, Ta, and Ti. The coil insulating layers 32 and 38 are made of an organic insulating material such as a resist. The upper surfaces of the coil insulating layers 32 and 38 are flattened, and the auxiliary yoke layer 33 and the return yoke layer 40 are formed on the flat surfaces. A protective layer 43 made of Al ₂ O ₃ is formed on the return yoke layer 40.

  In the separation layer 20 interposed between the reproducing element R and the recording element W, a heater 21 that generates heat when energized is provided. For example, as shown in FIG. 2, the heater 21 includes a pair of planar M-shaped heat generating regions 21 a that actually generate heat, and a pair of heat generating regions 21 a that extend from both ends in the track width direction to the depth direction rear side. And an extraction electrode 21b. The pattern shape of the heat generating region 21a is arbitrary, and may be a meander shape. The pair of extraction electrodes 21b are power feeding electrodes formed wider than the heat generating region 21a. The heater 21 is formed by sputtering using, for example, NiFe, CuNi, or CuMn.

  Heat generated from the heater 21 is transmitted toward the medium facing surface F, and causes the element portion (the main magnetic pole layer 34 of the reproducing element R and the recording element W) to locally protrude toward the recording medium M by thermal expansion. At this time, as the amount of heat transmitted from the heater 21 to the element portion increases, the protrusion amount of the element portion increases, and the facing distance between the element portion and the recording medium M becomes shorter, thereby improving the recording / reproducing characteristics.

In the thin film magnetic head H <b> 1 having the above configuration, the heat radiation suppressing layer 3 made of an insulating material having a lower thermal conductivity than the undercoat film 2 is provided in the recess 2 a of the undercoat film 2. In the present embodiment, the undercoat layer 2 is formed of Al ₂ O _3, the heat radiation suppressing layer 3 is formed of SiO _2. The thermal conductivity 1.32 W / (m · K) of SiO ₂ is 1/10 or less of the thermal conductivity 21 W / (m · K) of Al ₂ O ₃ . The slider 1 is made of Al ₂ O ₃ .TiC as described above, and has a thermal conductivity equivalent to that of the undercoat film 2. Due to this difference in thermal conductivity, the heat radiation suppressing layer 3 is less likely to escape heat than the undercoat film 2, and heat transmitted from the heater 21 and the element portion to the slider 1 side is kept in the layer. Heat dissipation from 1 can be suppressed.

  FIG. 2 shows a planar shape of the heat dissipation suppressing layer 3. The heat dissipation suppressing layer 3 is formed in a region overlapping both the reproducing element R and the heater 21 in the stacking direction so as to have a structure in which the reproducing element R is sandwiched between the heat dissipation suppressing layer 3 and the heater 21 in the stacking direction. The planar shape of the heat dissipation suppressing layer 3 is defined by the recess 2a provided in the undercoat film 2, and is rectangular in the illustrated embodiment. The dimensions of the heat dissipation suppressing layer 3 in the track width direction and the height direction are set sufficiently larger than the dimensions of the reproducing element R, the main magnetic pole layer 34 of the recording element W, and the heat generation area 21a of the heater 21 in the track width direction and the height direction. is there. As the planar size of the heat dissipation suppressing layer 3 increases, the ratio of the amount of heat remaining in the heat dissipation suppressing layer 3 out of the total amount of heat transferred from the element portion and the heater 21 to the slider 1 increases. The ratio of the amount of heat that escapes to 1 decreases. The heat dissipation suppressing layer 3 is formed so as to recede from the medium facing surface F in the height direction and is not exposed to the medium facing surface F. By not exposing to the medium facing surface F, it is possible to avoid problems such as local dents and smearing due to a polishing processing rate difference with the undercoat film 2 during the polishing step for forming the medium facing surface F. it can. In the present embodiment, it is retracted from the medium facing surface F by about 2 μm in the height direction.

The heat dissipation suppressing layer 3 is formed by forming an undercoat film 2 made of Al ₂ O ₃ on the trailing end face 1b of the slider 1 and cutting a part of the undercoat film 2 by, for example, ion milling to suppress heat dissipation. a recess 2a for defining the forming regions and the planar shape of the layer 3, by forming the SiO ₂ within the recess 2a, can be formed.

  In the thin film magnetic head H1 of the first embodiment, when heat is transferred from the heater 21 to the element portion (the main magnetic pole layer 34 of the reproducing element R and the recording element W), the temperature of the element portion and its surroundings rises and thermal expansion occurs. As a result, the element portion protrudes toward the recording medium M. At this time, the heat of the heater 21 is further propagated from the element portion to the slider 1 side, and is transmitted to the heat dissipation suppressing layer 3 positioned below the reproducing element R and the heater 21. As described above, the heat dissipation suppressing layer 3 is less likely to escape heat than the undercoat film 2 and functions to retain heat in the layer. Thereby, as schematically shown in FIG. 3, heat that should be radiated from the slider 1 stays between the heater 21 and the heat dissipation suppressing layer 3 unless the heat dissipation suppressing layer 3 exists, and the element portion (particularly, Heat is intensively applied to the reproducing element R) sandwiched between the heater 21 and the heat radiation suppressing layer 3. The heat generated from the heater 21 in this way does not immediately radiate from the slider 1 but largely contributes to the protrusion of the element portion, and the undercoat film 2 is provided on the entire trailing end face 1b. Compared with, the heater thermal efficiency is greatly improved. If the heat efficiency of the heater is improved, the element portion can be protruded greatly with a small input power, and low power can be realized.

FIG. 4 is a longitudinal sectional view showing the structure of the thin film magnetic head H2 according to the second embodiment of the present invention, cut at the center of the element. In the second embodiment, a heat radiation suppressing layer made of an insulating material having a lower thermal conductivity than the undercoat film 2 is used instead of the undercoat film 2 in a region overlapping both the reproducing element R and the heater 21 in the stacking direction. 3 is an embodiment. This heat dissipation suppressing layer 3 is formed by forming an undercoat film 2 made of Al ₂ O ₃ on the trailing end face 1b of the slider 1 over the entire surface and overcoating both the reproducing element R and the heater 21 in the stacking direction. It is obtained by removing the film 2 and forming SiO ₂ in the removed portion. Alternatively, a SiO ₂ film is entirely formed on the trailing end face 1b of the slider 1, and this SiO ₂ film is patterned and left in a desired shape in a region overlapping both the reproducing element R and the heater 21 in the stacking direction, It can be obtained by forming the undercoat film 2 filling the periphery of the SiO ₂ film with Al ₂ O ₃ . The configuration other than whether or not the undercoat film 2 is left under the heat dissipation suppressing layer 3 is the same as that in the first embodiment.

  FIG. 5 shows a thin film magnetic head (Example) having a heat dissipation suppression layer, a thin film magnetic head (Comparative Example 1) not having a heat dissipation suppression layer, and a thin film magnetic head having a heat conduction suppression layer instead of the heat dissipation suppression layer ( It is a graph which shows the result of having measured the protrusion amount to the recording medium M side of the thin film magnetic head at the time of heater energization about comparative example 2). The horizontal axis of the graph is the distance [μm] from the alumina edge α, and the vertical axis is the protrusion amount [nm] of the thin film magnetic head. Here, the distance from the alumina edge α is a distance representing the trailing edge (the upper surface position of the protective layer 43) as the reference position 0, the vicinity of 33 to 37 μm indicates the vicinity of the reproducing element, and the vicinity of 26 to 30 μm is the vicinity of the recording element. Is shown. Further, the protrusion amount of the thin film magnetic head is a value measured with the one end face 1a facing the recording medium M of the slider 1 when the heater is not energized as the reference plane 0.

  An example is the thin-film magnetic head H1 of the first embodiment shown in FIGS. In the thin film magnetic head H1, as described above, the heat radiation suppressing layer 3 having a lower thermal conductivity than the undercoat film 2 is formed in a region overlapping both the reproducing element R of the undercoat film 2 and the heater 21 in the stacking direction. The reproducing element R is sandwiched between the heater 21 and the heat dissipation suppressing layer 3 in the stacking direction.

Comparative Example 1 is a thin-film magnetic head having an undercoat film made of Al ₂ O ₃ on the entire trailing end face of the slider, and the structure is the same as that of Example 1 except that no heat dissipation suppressing layer is provided. is there.

  Comparative Example 2 has a thin film magnetic head structure described in Patent Document 2 (particularly FIG. 5), and is a thin film magnetic head provided with a heat conduction suppressing layer 47 immediately below the heating element 46. The heat conduction suppressing layer 47 is made of, for example, a heat-effect resist layer or the like, and has a thickness of about 0.3 μm to 0.4 μm. A heat radiating portion 48 is provided in the upper layer of the heating element 46.

  In the above embodiment and Comparative Examples 1 and 2, the conditions for measuring the protrusion amount of the thin film magnetic head (for example, the magnitude of power input to the heater and the time) are all the same.

  Referring to FIG. 5, in both the example and the comparative examples 1 and 2, the recording element M protrudes in the vicinity of the reproducing element and in the vicinity of the recording element, and the protruding amount in the vicinity of the reproducing element is larger than the recording element side. The trend is slightly larger.

  In Comparative Example 2, the amount of protrusion in the lower layer (the distance from the alumina edge α is 28 μm or more) below the recording element is smaller than that in Comparative Example 1, and the upper layer (the distance from the alumina edge α exceeds 25 μm) than the recording element. The amount of protrusion in (range) is larger than that in Comparative Example 1. This is because the portion of the heat generated from the heating element 46 that has propagated to the substrate side is blocked by the heat conduction suppression layer 47 and the amount of heat received by the heat radiating portion 48 increases, and a large amount of heat is released from the heat radiating portion 48. It is thought that it was because of. When the heat conduction suppressing layer 47 is provided immediately below the heating element 46 as described above, it is difficult to concentrate the amount of heat on the element portion (increase the amount of heat contributing to the protrusion of the element portion). According to Comparative Example 2, the heater thermal efficiency is deteriorated as compared with Comparative Example 1.

  On the other hand, the example is similar to the graph shape of Comparative Example 1, and the amount of protrusion is larger than that of Comparative Example 1 in the vicinity of the reproducing element and the recording element. Thereby, it can be seen that the heat dissipation suppression layer 3 provided in the undercoat film 2 suppresses heat dissipation from the slider 1, in other words, the amount of heat contributing to the protrusion of the element portion increases. According to this example, it is clear that the heater thermal efficiency is improved as compared with Comparative Examples 1 and 2.

  Although the embodiment in which the present invention is applied to the perpendicular recording type thin film magnetic head has been described above, the present invention is naturally applicable to a longitudinal recording type thin film magnetic head.

FIG. 3 is a cross-sectional view showing the structure of the thin-film magnetic head according to the first embodiment of the present invention cut at the center of the element, and corresponds to a cross-sectional view taken along line II in FIG. 2. It is a top view which shows the planar shape of the heat dissipation suppression layer of FIG. It is a schematic cross section explaining how to transmit heat generated from a heater. It is sectional drawing which cut | disconnects and shows the structure of the thin film magnetic head by 2nd Embodiment of this invention in the element center. It is the graph which measured the protrusion of the thin film magnetic head at the time of heater energization.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slider 1b Trailing end surface 2 Undercoat film 3 Heat radiation suppression layer α Alumina edge R Reproducing element W Recording element H1, H2 Thin film magnetic head

Claims (5)

A reproducing element formed on the undercoat film on the surface of the head substrate, a recording element formed above the reproducing element, and formed between the reproducing element and the recording element. In a thin film magnetic head comprising a heater for projecting at least one of the recording elements to the recording medium side by thermal expansion,
A thin film magnetic head, wherein a heat dissipation suppressing layer having a lower thermal conductivity than the undercoat film is provided in the undercoat film so as to be positioned at least in a region overlapping with the reproducing element and the heater in the stacking direction. 2. The thin film magnetic head according to claim 1, wherein the heat conductivity of the heat dissipation suppressing layer is 1/10 or less of the heat conductivity of the undercoat film. According to claim 1 or 2 thin film magnetic head according, the undercoat layer is formed of Al ₂ O _3, the heat radiation suppressing layer thin-film magnetic head has formed of SiO _2. 4. The thin film magnetic head according to claim 1, wherein the heat dissipation suppressing layer has a larger area than at least the element area of the reproducing element and the recording element. 5. The thin film magnetic head according to claim 1, wherein the heat dissipation suppressing layer is formed so as to recede from the surface facing the recording medium to the back side in the height direction.

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