JP4066025B2 - REPRODUCTION HEAD, COMPOSITE-TYPE THIN FILM MAGNETIC HEAD, AND MAGNETIC RECORDING DEVICE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reproducing head, a composite thin film magnetic head, and a magnetic recording apparatus, and in particular, a magnetic structure having a so-called CPP (Current Perpendicular to Plane) structure in which a sense current flows in the film thickness direction of a magnetic sensing film. The present invention relates to a reproducing head, a composite thin-film magnetic head, and a magnetic recording device that are characterized by a configuration for reducing an electrode resistance value in the head.
[0002]
[Prior art]
The reproducing head of a hard disk device senses the direction of the magnetic field leaking from the disk and reads information using the magnetoresistive effect in which the electrical resistance changes. Currently, this reproducing head is used to read the resistance change. A CIP (Current in Plane) structure is used in which a sense current flows in parallel to the magnetoresistive film.
[0003]
However, with the recent increase in hard disk drive capacity, the recording area per bit is decreasing and the core width is becoming narrower. With the CIP structure, the resistance value decreases as the density increases. There is a problem that the output decreases.
[0004]
On the other hand, in the magnetoresistive film having the CPP structure, the sense current for reading the resistance change flows in the direction perpendicular to the magnetoresistive film, so that an output can be obtained regardless of the core width and suitable for high density. ing.
[0005]
Here, a conventional magnetoresistive element having a CPP structure will be described with reference to FIG.
FIG. 9A is a schematic cross-sectional view of a conventional CPP structure spin valve magnetoresistive effect element. On the lower electrode 61 which also serves as a lower shield layer, an antiferromagnetic layer 62, The pinned ferromagnetic layer whose magnetization direction is fixed in one direction by the antiferromagnetic layer 62, that is, the pinned layer 63, the nonmagnetic intermediate layer 64, and the magnetization direction are easily affected by the magnetic field from the magnetic recording medium. The free ferromagnetic layer is changed to a free layer 65, and an upper electrode 66 serving also as an upper shield layer is provided so as to be electrically connected to the free layer 65.
Reference numeral 67 denotes a planarizing layer such as Al ₂ O ₃ .
[0006]
When a sense current is passed in the perpendicular direction to the spin valve magnetoresistive film having the CPP structure, the resistance changes depending on the magnetization directions of the pinned layer 63 and the free layer 65, and the magnetic sensor functions as a magnetic sensor for reading the magnetic field.
[0007]
Antiferromagnetic materials important for the production of this spin valve film have excellent corrosion resistance, a large unidirectional anisotropic magnetic field for fixing the magnetic layer, and a temperature at which the anisotropy is lost by heat ( Although an antiferromagnetic material that satisfies this property requires heat treatment during fabrication, ordered alloys such as PdPtMn and PtMn are known as excellent materials that satisfy this condition. Yes.
[0008]
In the reproducing head using the magnetoresistive effect film having the CPP structure, as shown in FIG. 9A, the magnetic shield layers are provided above and below the magnetoresistive effect film so as to serve as the upper and lower electrodes. Compared to a reproducing head using a magnetoresistive film having a CIP structure provided separately from the electrode, the gap length can be narrowed by an insulating layer necessary for insulating and separating the magnetic shield layer and the electrode. There are features.
[0009]
In such a CPP structure magnetoresistive effect element, NiFe, FeN, or the like is used as an electrode that also serves as a magnetic shield layer. However, this NiFe, FeN, etc. are more in proportion than the electrode materials that are generally used. Since the resistance is high, when a sense current is passed, the resistance other than the element portion that causes the magnetoresistive effect increases, and as a result, the output decreases.
[0010]
As shown in FIG. 9B, as shown in the drawing, the current inflow direction of the upper electrode 66 and the lower electrode 61 is determined from the difference in specific resistance value at the joint surface between the upper electrode 66 and the lower electrode 61 and the magnetoresistive effect film. There is a problem that the concentration of the sense current occurs at the end close to.
[0011]
Therefore, in order to prevent such current concentration, the magnetic shield layer and the electrode layer are separately provided, but it is proposed to form a metal film having a low specific resistance on the magnetoresistive film ( For example, refer to Patent Document 1), and will be described with reference to FIG.
[0012]
FIG. 10 is a schematic cross-sectional view of a CPP-structured spin valve magnetoresistive element according to the above proposal. The giant magnetoresistive film 73 and Au are formed on the lower magnetic shield layer 71 via the lower electrode 72. A low resistivity metal layer 74 such as Cu, Cu, or Ta is laminated and patterned into a predetermined shape, and then a magnetic domain control layer 76 is provided via an insulating layer 75. The surface of the magnetic domain control layer 76 is covered with an insulating layer 77. After that, the upper electrode 78 and the upper magnetic shield layer 79 are sequentially deposited.
[0013]
In this way, since the low resistivity metal layer 74 is provided so as to be in contact with the giant magnetoresistive effect film 73, the sense current is sufficiently spread in the in-plane direction of the giant magnetoresistive effect film 73, thereby suppressing current concentration. it can.
[0014]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-280636
[Problems to be solved by the invention]
However, Ta [1.23 × 10 ⁻⁵ Ω · cm (at 0 ° C.)] in the material of the low resistivity metal electrode mentioned in the above-mentioned Patent Document 1 has a specific resistance as compared with other materials. There is a problem that current is uniform and current equalization is not always sufficient.
[0016]
On the other hand, Cu [1.55 × 10 ⁻⁶ Ω · cm (at 0 ° C.)] and Au [2.05 × 10 ⁻⁶ Ω · cm (at 0 ° C.)] are sufficient in terms of specific resistance, but Au is It is expensive and greatly hinders cost reduction of the magnetic head.
[0017]
On the other hand, Cu has poor corrosion resistance and may be damaged during the process of manufacturing the magnetic head. On top of that, a protective film such as Au, Ta, Pt, W, and Mo is protected as a protective film. It is necessary to provide it as a film.
[0018]
However, as shown in FIG. 11, when the low resistance contact electrode having such a two-layer structure is provided, the low resistivity contact electrode is formed by heat treatment for ordering the antiferromagnetic layer 81 such as PdPtMn. Another problem arises that the interface between the two metal electrodes 82 and the protective layer 83 is dissolved to form an alloy layer 85 and the resistance is increased.
Such an increase in electrode resistance leads to an increase in resistance other than the magnetoresistive film, and must be avoided.
In the figure, reference numeral 84 denotes an upper magnetic shield layer.
[0019]
Al [2.50 × 10 ⁻⁶ Ω · cm (at 0 ° C.)] has no problem in terms of specific resistance, but like Cu, it has a poor corrosion resistance, so it is necessary to provide a protective layer. However, the heat treatment for ordering the antiferromagnetic material causes a problem that the interface between the two metal electrodes is dissolved and the resistance increases.
[0020]
Accordingly, an object of the present invention is to provide a low resistance contact electrode structure that prevents current concentration at low cost.
[0021]
[Means for Solving the Problems]
FIG. 1 is a block diagram showing the principle of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
In the figure, reference numerals 1, 7, 8, and 9 denote a magnetic shield layer, an insulating layer, a magnetic domain control layer, and an insulating layer, respectively.
In order to achieve the above object, the present invention relates to at least one of the magnetic shield layer 6 and the magnetoresistive effect in a reproducing head including a magnetoresistive effect element that allows a sense current to flow in a direction perpendicular to the magnetoresistive effect film 2. A first electrode layer 3 and a second electrode layer 5 made of dissimilar metals having a specific resistance lower than that of the magnetic shield material are provided between the films 2 and between the first electrode layer 3 and the second electrode layer 5. Further, a conductive layer 4 that is insoluble in the metal constituting the first electrode layer 3 and the second electrode layer 5 is inserted.
[0022]
In this way, when an electrode layer having a low specific resistance is formed in the plane of the magnetoresistive effect film 2 in order to spread the sense current uniformly, the first electrode layer 3 which is inexpensive and has a low specific resistance and the low specific resistance are used. A second electrode layer 5 having excellent corrosion resistance and a metal constituting the first electrode layer 3 and the second electrode layer 5 between the first electrode layer 3 and the second electrode layer 5; By inserting the non-solid conductive layer 4, it is possible to prevent the first electrode layer 3 and the second electrode layer 5 from being alloyed, thereby suppressing an increase in electrode resistance.
[0023]
In this case, as the first electrode layer 3 in contact with the magnetoresistive effect film 2, a conductive material having a low specific resistance mainly composed of either Cu or Al is used, and Au, Ta, It is desirable to use a metal having excellent corrosion resistance such as Pt, Mo, or W.
[0024]
Further, as the conductive layer 4 insoluble in the metal constituting the first electrode layer 3 and the second electrode layer 5, any one of Ti, TiN, or TiW is desirable, so that the solid solution An increase in resistance value due to generation can be suppressed.
In general, it is known that a solid solution is formed at the metal interface when the difference in diameter between two kinds of metal atoms is within 15%. Therefore, the first electrode layer 3 and the second electrode layer 2 A metal different in diameter by 15% or more from both metals may be inserted between the electrode layers 5, and a typical material is Ti, but is not limited to a pure metal.
[0025]
In this case, it is desirable that the thickness of the conductive layer 4 insoluble in the metal constituting the first electrode layer 3 and the second electrode layer 5 is 10 to 30 nm, and if the thickness is less than 10 nm, the increase in electrical resistance is prevented. On the other hand, when the thickness exceeds 30 nm, the effect of preventing the increase in electrical resistance is saturated and the gap length only increases.
[0026]
In addition, it is desirable that the magnetic shield layer 6 be electrically connected to the second electrode layer 5 so as to serve also as an electrode layer, thereby simplifying the magnetoresistive effect element structure.
[0027]
In addition, a composite thin film magnetic head suitable for high-density recording can be configured by mounting the above-described reproducing head and inductive write head.
[0028]
Further, a high density recording magnetic recording apparatus is realized by combining this composite thin film magnetic head with a magnetic recording medium, a medium rotating mechanism, an arm on which the composite thin film magnetic head is mounted, and a mechanism for moving the arm. be able to.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Here, a magnetic head according to an embodiment of the present invention will be described. Before that, a change in sheet resistance after heat treatment in the low resistance contact electrode layer will be described with reference to FIGS.
[0030]
FIG. 2 is a schematic cross-sectional view of a contact electrode layer for measuring a change in sheet resistance after heat treatment in the low resistance contact electrode layer. The thickness is formed on a silicon substrate 11 using a sputtering method. For example, a Cu layer 12 as a low specific resistance layer having a thickness of 400 nm, a Ti layer 13 as a barrier layer, and an Au layer 14 having a thickness of, for example, 100 nm are sequentially formed.
[0031]
Next, after performing heat treatment for 3 hours at 300 ° C., which is the same heat treatment condition as that for producing an actual magnetoresistive effect film, the sheet resistance of the low resistance contact electrode layer is measured by a four-terminal method.
At this time, the thickness of the Ti layer 13 is set to four types of 0 nm, 10 nm, 30 nm, and 50 nm.
[0032]
3 FIG. 3 shows sheet resistance values measured for four types of samples. Compared to a film formed only of a Cu layer / Au layer (Ti layer 13 is 0 nm), the Ti layer 13 is Films inserted with 10 nm, 30 nm, and 50 nm have resistance values reduced by 53%, 65%, and 67%, respectively, confirming the effect of inserting Ti, which is a non-solid solution metal, with respect to Cu and Au. It was.
[0033]
Next, with reference to FIGS. 4 to 6, the manufacturing process of the composite thin film magnetic head according to the first embodiment of the invention will be described.
4A. First, on the Al ₂ O ₃ —TiC substrate 21, the lower part that also serves as a lower electrode made of, for example, NiFe and having a thickness of, for example, 0.5 μm via an Al ₂ O ₃ film 22. After forming the magnetic shield layer 23, a PdPtMn pinned layer 24 having a thickness of, for example, 13 nm, a CoFe pinned layer 25 having a thickness of, for example, 2.8 nm, and a Cu intermediate layer having a thickness of, for example, 2.5 nm 26 and a CoFe free layer 27 having a thickness of, for example, 3.0 nm are sequentially deposited to form the spin valve film 28.
[0034]
Next, after depositing a Cu layer 29 having a thickness of, for example, 400 nm, a Ti layer 30 having a thickness of, for example, 30 nm, and an Au layer 31 having a thickness of, for example, 100 nm, as shown in FIG. For example, the magnetization direction of the PdPtMn pinned layer 24 is fixed by performing an annealing process at 300 ° C. for 3 hours in a state where a magnetic field of 2T (Tesla) is applied.
In this annealing step, since the Ti layer 30 is provided, the Cu layer 29 and the Au layer 31 are not alloyed, and the low resistance characteristics can be maintained.
[0035]
Next, referring to FIG. 5C, this spin-valve film is etched into a 0.7 .mu.m.times.0.7 .mu.m square column shape by ion milling using the resist pattern 32 as a mask to form a sensor portion 33 and the lower magnetic shield layer 23. To expose.
[0036]
Next, referring to FIG. 5D, the Al ₂ O ₃ film 34 having a thickness of, for example, 15 nm and the CoCrPt film having a thickness of, for example, 30 nm are formed on the entire surface by sputtering while the resist pattern 32 is provided. 35 and an Al ₂ O ₃ film 36 having a thickness of, for example, 5 nm are sequentially deposited, and then the resist pattern 32 is removed to remove the CoCrPt film 35 insulated by the Al ₂ O ₃ films 34 and 36. A magnetic domain control film is formed.
[0037]
Next, referring to FIG. 5E, after patterning to a predetermined size with the magnetic domain control film, a planarizing layer (reference numeral 45 in FIG. 6) made of Al ₂ O ₃ or the like is formed, and then a resist frame made of a resist pattern The basic configuration of the spin-valve CPP magnetic sensor is obtained by forming the upper magnetic shield layer 37 that also serves as an upper electrode made of NiFe having a thickness of, for example, 1 μm, and then removing the resist frame. It is done.
[0038]
6 and the subsequent drawings, like the conventional induction type write head, the lower magnetic pole layer 39, the write gap layer 40 made of Al ₂ O ₃ , the resist on the upper magnetic shield layer 37 via the Al ₂ O ₃ film 38. After sequentially forming an interlayer insulating film 41 made of Cu, a planar spiral coil 42 made of Cu, and an interlayer insulating film 43, an upper magnetic pole layer 44 having a predetermined pattern is formed by a selective plating method.
[0039]
Next, an Al ₂ O ₃ protective film (not shown) is formed on the entire surface, and slider processing is performed to obtain a composite thin film magnetic head using a spin valve CPP magnetic sensor as a reproducing head.
[0040]
FIG. 7 is a plan view showing the shapes of the upper and lower magnetic shield layers after the slider processing. The sensor portion 33 is exposed on the polished end faces of the lower magnetic shield layer 23 and the upper magnetic shield layer 37.
[0041]
FIG. 8 is a plan view of a magnetic disk apparatus equipped with the composite thin film magnetic head according to the embodiment of the present invention. The magnetic disk apparatus is attached to the rotating shaft of the spindle motor 53 and fixed by the disk clamp ring 52. The basic configuration is composed of a magnetic disk 51 and a head arm 54 to which a slider 56 having a spin valve CPP magnetic sensor is attached via a suspension 55 at the tip.
[0042]
In the composite thin film magnetic head according to the embodiment of the present invention, when a low specific resistance conductive layer is provided in order to allow a sense current to flow uniformly in the plane of the spin valve film 28 having the CPP structure, the low specific resistance conductive layer is provided. In order to prevent the alloying with the Au layer serving as a protective layer, a Ti layer is interposed as a barrier metal so that the main part of the antiferromagnetic layer is made of an inexpensive and low specific resistance Cu layer. An increase in electrical resistance due to alloying can be prevented in the heat treatment step for fixing the magnetization direction.
[0043]
Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications can be made.
For example, in the above embodiment, the GMR film is used as the CPP structure magnetoresistive effect film, but it is not limited to the GMR film, and instead of the Cu intermediate layer, the thickness of the Al— A TMR (tunnel magnetoresistive effect) film provided with oxide may be used.
[0044]
In the above embodiment, the main part of the low specific resistance conductive layer is made of Cu. However, the present invention is not limited to Cu, and it is possible to use Al which is inexpensive and has a low specific resistance like Cu. Further, it is not necessary to be a single metal element, and a conductive material mainly composed of Cu or Al may be used.
[0045]
In the above embodiment, the protective layer is made of Au. However, the protective layer is not limited to Au, and Pt, Ta, Mo, or W, which has excellent corrosion resistance like Au, can be used. It ’s good.
[0046]
In the above embodiment, the barrier layer is made of Ti. However, the barrier layer is not limited to Ti, and TiN or TiW may be used.
[0047]
In the above embodiment, the low specific resistance conductive layer is provided on the free layer side, but may be provided on the antiferromagnetic layer side.
Furthermore, although it may be provided in both, in this case, the gap length becomes large.
[0048]
In the above embodiment, the spin valve film is a type in which the antiferromagnetic layer is on the substrate side. However, a spin valve film in which the substrate side is a free layer may be used.
[0049]
In the above embodiment, the spin valve film is a single spin valve film. However, the present invention is not limited to a single spin valve film, and a dual spin valve film may be used.
[0050]
In the above embodiment, the pinned layer and the free layer are composed of a single-layer magnetic layer. However, at least one of the pinned layer and the free layer may be composed of a multilayer structure. The layer may have a laminated ferri structure.
[0051]
In the above embodiment, the magnetic head is a composite thin film magnetic head, but a single reproducing head consisting only of a spin valve CPP magnetic sensor is also targeted.
[0052]
Here, the detailed features of the present invention will be described again with reference to FIG.
See FIG. 1 again (Appendix 1) In a reproducing head including a magnetoresistive effect element that allows a sense current to flow in a direction perpendicular to the magnetoresistive effect film, a ratio between at least one of the magnetic shield layer 6 and the magnetoresistive effect film 2 A first electrode layer 3 and a second electrode layer 5 made of dissimilar metals whose resistance is lower than that of the magnetic shield material are provided, and the first electrode layer 3 and the second electrode layer 5 are provided between the first electrode layer 3 and the second electrode layer 5. A reproducing head in which a conductive layer 4 insoluble in the metal constituting the electrode layer 3 and the second electrode layer 5 is inserted.
(Supplementary Note 2) The first electrode layer 3 in contact with the magnetoresistive effect film 2 is made of a conductive material mainly containing either Cu or Al, and the second electrode layer 5 is made of Au, Ta, Pt, 2. The reproducing head according to appendix 1, wherein the reproducing head is made of either Mo or W.
(Supplementary Note 3) The conductive layer 4 insoluble in the metal constituting the first electrode layer 3 and the second electrode layer 5 is made of any one of Ti, TiN, or TiW. The reproducing head according to appendix 2.
(Supplementary note 4) The supplementary note 2 or 3 is characterized in that the thickness of the conductive layer 4 insoluble in the metal constituting the first electrode layer 3 and the second electrode layer 5 is 10 to 30 nm. The described reproduction head.
(Supplementary note 5) The reproducing head according to any one of supplementary notes 1 to 4, wherein the magnetic shield layer 6 is electrically connected to the second electrode layer 5 and also serves as a terminal electrode layer.
(Additional remark 6) The composite type thin film magnetic head which mounts the reproducing head of any one of Additional remark 1 or 5, and the induction type write head.
(Appendix 7) The composite thin film magnetic head, the magnetic recording medium, the medium rotation mechanism, the arm on which the composite thin film magnetic head is mounted, and the mechanism for moving the arm are provided. Magnetic recording device.
[0053]
【The invention's effect】
According to the present invention, the main part of the low specific resistance conductive layer provided on the top surface of the magnetoresistive effect film is constituted by a low cost and low specific resistance conductive layer, and a barrier is formed to prevent alloying with the protective layer. Since the metal is interposed, it is possible to prevent an increase in electrical resistance due to alloying in the heat treatment process for fixing the magnetization direction of the antiferromagnetic layer, thereby reducing the reproduction output accompanying the increase in the density of the hard disk. In other words, it greatly contributes to the realization of a high-sensitivity high-density magnetic recording apparatus.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a basic configuration of the present invention.
FIG. 2 is a schematic cross-sectional view of a contact electrode layer.
FIG. 3 is an explanatory diagram of the dependency of the sheet resistance value of the contact electrode layer on the thickness of the Ti layer.
FIG. 4 is an explanatory diagram of the manufacturing process up to the middle of the embodiment of the present invention.
FIG. 5 is an explanatory diagram of the manufacturing process up to the middle of FIG. 4 and subsequent steps of the embodiment of the present invention.
FIG. 6 is an explanatory diagram of the manufacturing process from FIG. 5 onward according to the embodiment of the present invention.
FIG. 7 is a plan view of a CPP structure reproducing head according to an embodiment of the present invention.
FIG. 8 is a plan view of a magnetic disk drive equipped with a composite thin film magnetic head according to an embodiment of the present invention.
FIG. 9 is an explanatory view of a conventional spin valve magnetoresistive element having a CPP structure.
FIG. 10 is a schematic cross-sectional view of an improved spin valve magnetoresistive element having a conventional CPP structure.
FIG. 11 is an explanatory diagram of problems when a two-layer structure low-resistance contact electrode is provided.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetic shield layer 2 Magnetoresistance effect film 3 1st electrode layer 4 Conductive layer 5 2nd electrode layer 6 Magnetic shield layer 7 Insulating layer 8 Magnetic domain control layer 9 Insulating layer 11 Silicon substrate 12 Cu layer 13 Ti layer 14 Au layer 21 Al ₂ O ₃ —TiC substrate 22 Al ₂ O ₃ film 23 Lower magnetic shield layer 24 PdPtMn pinned layer 25 CoFe pinned layer 26 Cu intermediate layer 27 CoFe free layer 28 Spin valve film 29 Cu layer 30 Ti layer 31 Au layer 32 Resist Pattern 33 Sensor part 34 Al ₂ O ₃ film 35 CoCrPt film 36 Al ₂ O ₃ film 37 Upper magnetic shield layer 38 Al ₂ O ₃ film 39 Lower magnetic pole layer 40 Write gap layer 41 Interlayer insulating film 42 Coil 43 Interlayer insulating film 44 Upper part Pole layer 45 Flattening layer 51 Magnetic recording medium 52 Disc clamp ring 53 Spindle motor 54 Head arm 55 Suspension 56 Slider 61 Lower electrode 62 Antiferromagnetic layer 63 Pinned layer 64 Nonmagnetic intermediate layer 65 Free layer 66 Upper electrode 67 Planarizing layer 71 Lower magnetic shield layer 72 Lower electrode 73 Giant magnetoresistive film 74 Low resistivity metal layer 75 Insulating layer 76 Magnetic domain control layer 77 Insulating layer 78 Upper electrode 79 Upper magnetic shield layer 81 Antiferromagnetic layer 82 Low resistivity contact electrode 83 Protective layer 84 Upper magnetic shield layer 85 Alloy layer

Claims (5)

In a reproducing head including a magnetoresistive effect element that allows a sense current to flow in a direction perpendicular to the magnetoresistive effect film, different metals having a specific resistance lower than that of the magnetic shield material between at least one magnetic shield layer and the magnetoresistive effect film The first electrode layer and the second electrode layer are provided, and the metal constituting the first electrode layer and the second electrode layer is not disposed between the first electrode layer and the second electrode layer. A reproducing head having a solid solution conductive layer inserted therein. The first electrode layer in contact with the magnetoresistive effect film is made of a conductive material mainly composed of either Cu or Al, and the second electrode layer is made of Au, Ta, Pt, Mo, or W. The reproducing head according to claim 1, comprising: 3. The reproduction according to claim 2, wherein the conductive layer insoluble with the metal constituting the first electrode layer and the second electrode layer is made of Ti, TiN, or TiW. head. 4. A composite type thin film magnetic head comprising the reproducing head according to claim 1 and an inductive write head. 5. A magnetic recording apparatus comprising at least the composite thin film magnetic head according to claim 4, a magnetic recording medium, a medium rotating mechanism, an arm on which the composite thin film magnetic head is mounted, and a mechanism for moving the arm. .

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