JPH08115511A - Flux guide type gmr head - Google Patents

Abstract

PURPOSE: To obtain a sufficient S/N even in the case of a high track density by making a flux guide thinner than a read head in film thickness. CONSTITUTION: The dual head is equipped with an upper magnetic shield 90 mounted with an upper magnetic core 110 also commonly used as a lower magnetic core, a flux guide 100 provided between the upper magnetic shield 90 and a lower magnetic shield 10, a GMR film 60 and one pair of electrodes 70 for impressing a detecting current on the GMR film. The upper and lower shield layers 90 and 10 are disposed to prevent leakage magnetic field from a magnetic disk from affecting the film 60 and to enhance the signal resolution of the GMR film 60. The flux guide 100 is desirably formed out of a ferromagnetic film for constituting the GMR film 60, and its film thickness is formed thinner than the signal detecting electrode 70 formed between the write head 110 and the lower magnetic shield film 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a narrow track magnetic head applicable to track densities of 10 kTPI or higher, and more particularly to a flux guide type GMR head capable of high output and high reliability.

[0002]

2. Description of the Related Art A magnetoresistive (MR) type thin film magnetic head generally applied to a magnetic disk drive is a read-only magnetic head utilizing a phenomenon in which the electric resistance of the MR film is changed by a magnetic field from the magnetic disk. Usually, it is used as an MR / inductive composite magnetic head in combination with an inductive magnetic head for writing. This M
The R head is used as shown in FIG. 8 showing the structure of a magnetic disk device. As shown in FIG. 1, the R head has a lower magnetic shield 10 made of a magnetic material and an upper magnetic core 110 of an inductive magnetic head. An MR element is arranged between the upper magnetic shield 90 and the upper magnetic shield 90.

This MR element is a laminated film composed of an MR film and a bias film for applying a transverse bias magnetic field to the MR film, and further applies a longitudinal bias magnetic field to the MR film to maintain a single magnetic domain state. Magnetic domain control layers and electrodes are arranged at the left and right ends.

In such an MR head, while applying a lateral bias magnetic field from the bias film to the MR film, the MR head relatively moves on the magnetic disk by the detected current from the electrodes, and thus the MR field receives the magnetic field from the magnetic disk. The data is reproduced by detecting the change in the resistance value of the detection current flowing through the film. The MR head converts a magnetic signal on the recording medium into an electric signal by utilizing a phenomenon that the electric resistance of the MR film changes depending on the direction of magnetization. This change is called an anisotropic magnetoresistive (AMR) effect, and is given by cos ² with respect to the angle between the magnetization vector of the MR film and the signal magnetic field.

Recently, a technique for obtaining an enhanced MR effect, which is larger than the MR change of the AMR effect, has been reported. One of the references that reported this technology is "Enhanced Magn
etoresistance in Layered Magnetic Structures with
Antiferromagnetic Interlayere Exchange ", G. Binash
et al., Phys. Rev. B. 4828 (1989), describes a method for obtaining an enhanced MR effect caused by antiparallel arrangement of magnetization by forming a multilayer structure of a magnetic film and a non-magnetic film. There is. However, the saturation magnetic field required to obtain this resistance change is high and non-linear, and the film structure described in this report cannot be immediately used as an improved magnetic head for the MR head.

A method for solving this problem is described in Japanese Patent Laid-Open No. 4-358310. The object of the above patent is to provide a spin-valve type GMR head that is enhanced by AMR and exhibits an MR effect having a sufficient linear response with a small applied magnetic field. That is, the head structure using this technique is composed of a first ferromagnetic film and a second ferromagnetic film separated by a thin nonmagnetic metal layer, and has a means for fixing the magnetization direction of at least one of the ferromagnetic films. A magnetic head having the same is disclosed, which is a kind of GMR head.

[0007]

In order to prevent a decrease in output in the future increase in track density, the spin valve type magnetic head having an MR effect enhanced from the AMR effect is used. However, the above conventional technique has the following problems. In order to obtain the enhanced MR effect, it is indispensable to use a multilayer film including a ferromagnetic film and a non-magnetic film, and there is a concern about the reliability of application of the magnetic head. This is because problems such as diffusion at the interface of the multilayer film due to temperature history during the element forming process and corrosion during the processing process occur. Furthermore, 10
At a high track density of kTPI or more, the track width is in the submicron region, so that the output is inevitably reduced, and a countermeasure is required.

The object of the present invention is to enhance the enhanced MR.
It is an object of the present invention to provide a head structure which uses a GMR head having an effect and has no problem in reliability when applied to a magnetic head, and which can cope with a reduction in output at a high track density of 10 kTPI or more.

[0009]

In order to achieve the above object, the present invention has a first feature that it is a GMR head provided with a flux guide. Here, it is characterized in that the film thickness of the flux guide is thinner than the GMR film thickness serving as a read head. A second feature of the present invention is that the flux guide is made of a ferromagnetic film that is a part of a multilayer film that constitutes the GMR film. Furthermore, at least one of a permanent magnet film and an antiferromagnetic film is applied to the magnetic domain control layer that applies a longitudinal bias and a transverse bias magnetic field. Both of them have different coercive force in the case of a permanent magnet film and blocking temperature in the case of an antiferromagnetic film. Is the third feature.

Further, according to the present invention, in the magnetic head according to the first or second characteristic, the ferromagnetic film forming the GMR film is a magnetic alloy film containing at least one of Fe, Co or Ni. The fourth feature is that the nonmagnetic film forming the enhancement MR film separates the ferromagnetic film, and the nonmagnetic film is copper, silver, gold and an alloy or a laminated film of two or more kinds of them. The fifth characteristic.

According to the above-mentioned means of the present invention, not only the element forming process of the GMR head can be stabilized, but also 10 kT
A head structure capable of coping with a reduction in output at a high track density of PI or higher becomes possible.

[0012]

In the first and second features, since the flux guide is provided on the medium facing surface, the influence on the enhancement layer MR film during the processing process is eliminated, and the problem of reliability deterioration due to corrosion can be solved. Further, in this magnetic head, the recording magnetic field of the medium is changed to G by using the flux guide.
Due to the structure of guiding to the MR film, the magnetic sensitive portion of the GMR film can be made wider than the track width, and the reduction in output due to the narrow track can be prevented.

In the second feature, the flux guide is formed of a ferromagnetic film which is a part of the multilayer film forming the GMR film, so that the signal magnetic field from the medium can be effectively used.
It is possible to guide up to the film, so that a magnetic head with a wide track width can be applied. As a result, a large resistance change can be used and the head output can be improved. Furthermore, it is desirable to provide a base film between the ferromagnetic film forming the flux guide and the gap film. This is because good soft magnetic characteristics can be obtained even when the substrate temperature is low when forming a part of the ferromagnetic film of the multi-layered film forming the GMR film. The advantage of lowering the substrate temperature is that the margin of interface controllability of the laminated film at the time of forming the GMR film is expanded. The base film is preferably Ta or Hf.

Further, in the magnetic heads according to the first and second characteristics, the resistance change amount of the GMR film is increased by optimizing the materials and thicknesses of the ferromagnetic film and the nonmagnetic film forming the GMR film. In addition, the magnetic field sensitivity can be increased. By adopting the above advantages and the flux guide type, the read track width of the GMR head can be expanded and the output can be further improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the flux guide type GMR head of the present invention will be described in detail below with reference to the drawings. FIG.
2 is a diagram for explaining a dual head including a GMR head according to this embodiment, and FIG. 2 is a GM according to this embodiment.
It is an expansion perspective view of an R film part. Note that in FIG. 1, one half surface of the write head above the upper shield film 90 is omitted, and in FIG. 2, the upper gap film and the upper shield film 90 are omitted.

The dual head shown in FIG. 1 is provided between an upper magnetic shield 90 serving also as a lower magnetic core on which an upper magnetic core 110 of an inductive magnetic head is mounted, and between the upper magnetic shield 90 and the lower magnetic shield 10. The flux guide 100 and the GMR which are the features of the present invention
The film 60 and a pair of electrodes 70 for applying a detection current to the MR film are provided.

It is desirable that the flux guide is made of a ferromagnetic film having a soft magnetic characteristic which constitutes the GMR film.
This is because the signal magnetic field from the recording medium can be efficiently guided to the GMR film. As shown in FIG. 2, the detailed structure of the flux guide type GMR head is composed of a first ferromagnetic film separated by a thin metal film (base film) 102 on the lower gap film 20. Here, the GMR film 60 is a spin valve type having means for fixing the magnetization direction of at least one ferromagnetic film. A pair of signal extracting electrodes 70 formed by a lift-off method at predetermined positions on the GMR film at predetermined intervals, an upper gap film formed so as to cover each film / layer / electrode, and And an upper magnetic shield layer formed on the upper gap film.

Next, the function and material of each layer / film will be described.

First, the upper / lower magnetic shield layer 9
0 and 10 are arranged on the GMR film 60 to prevent the influence of the leakage magnetic field from the magnetic disk and to improve the signal resolution of the GMR film 60.
It is a ferromagnetic alloy film exhibiting soft magnetic characteristics such as Co-based amorphous / Co-based crystalline and Fe-based crystalline, and the film thickness is approximately 0.5 to
3 μm is desirable.

Upper and lower gap films 80 and 20
Is arranged so as to sandwich the flux guide type GMR film 60, electrically isolates the GMR film 60 from the upper / lower magnetic shield layers 90/10, and adds another oxide to the alumina film and alumina. The film is made of a non-magnetic and insulating material. Since the film thickness affects the reproduction resolution of the GMR head, it depends on the recording density desired for the magnetic head. For example, when used in a high recording density region of 10 kTPI or more, the gap film thickness is 0.2 to 0.05 μm. Is within the range of.

Incidentally, these upper / lower gap films 80/2
When the film thickness of 0 is 0.2 μm or less, the breakdown voltage is lowered. Therefore, a bias is applied during film formation, the film is formed in a gas in which H ₂ or He is mixed with Ar as a sputtering gas, or SiO ₂ is formed on alumina. Alternatively, Ta ₂ O ₅ is added to reduce the pinholes in the film and improve the film quality of alumina to improve the breakdown voltage.

In the GMR film, as shown in FIG. 3, the first ferromagnetic film 3 whose magnetization vector operates in response to the signal magnetic field.
5 and the second ferromagnetic film 45 whose magnetization vector is fixed in one direction, the magnetization directions are parallel /
It utilizes anti-parallelism. The behavior of this magnetization vector will be described.

FIG. 5 schematically shows the structure of the magnetically sensitive portion shown in FIG. 3, and shows the magnetization vectors of the first / second ferromagnetic films 35/45 when a current is applied. It is indicated by a thick arrow I / U. In the figure, arrow a indicates the change of the magnetization vector of the ferromagnetic film 35 of the free layer, which is sensitive to the signal magnetic field.
The arrow c indicates the ferromagnetic film 45 so that it is not sensitive to the signal magnetic field.
Antiferromagnetic film or permanent magnet film 5 for fixing the magnetization vector of
It is adjacent to 0, indicating that the magnetization vector is fixed in one direction with respect to the signal magnetic field.

The GMR film is called a spin valve MR head, but the present invention is not limited to this.
Ordinary GMR in which a ferromagnetic film 35 and a non-magnetic film 40 are multilayered
It can also be applied to membranes.

Flux guide 1 which is a feature of this embodiment
00 is preferably formed of a ferromagnetic film forming the GMR film. This is due to the configuration of the present invention,
This is because the signal magnetic field can be effectively guided to the GMR film. This action will be described later.

Next, the first / second part of the GMR film 60 is formed.
FIG. 6 shows the relationship between the magnetic coupling between the ferromagnetic films 35/45 and the non-magnetic film thickness separating the ferromagnetic films. It is shown that the magnetic coupling force between the ferromagnetic films vibrates antiferromagnetically-ferromagnetically in a cycle of 5 to 10 Å, and the nonmagnetic film thickness becomes almost zero at 20 Å. The state of this vibration is similar to that of a GMR film in which a ferromagnetic film and a non-magnetic film are laminated. In the spin valve type GMR film shown here, the coupling between the ferromagnetic layers also vibrates. The non-magnetic film thickness of the GMR film used is
20Å is desirable because the magnetic coupling force between the ferromagnetic films is close to zero and the amount of resistance change does not decrease.

Furthermore, since the coupling between the ferromagnetic layers changes due to the change in the non-magnetic film thickness, the influence of the change in the non-magnetic film thickness due to the diffusion between the non-magnetic film and the magnetic film due to the thermal history of the element forming process. I'm worried. However, it has been separately confirmed that the magnetic coupling does not change at a thermal history up to 200 ° C., and it is necessary to set the maximum temperature of the head element forming process to 200 ° C. or less.

The GMR film can be realized not only with the film structure shown in FIG. 3 but also with the film structure shown in FIG. However, the film structure shown in FIG. 3 is superior in terms of the margin of film forming conditions. This is because the film structure of FIG. 4 has a limitation that the magnetization fixed layer 50 is located below the laminated film with respect to the free ferromagnetic film 35 in the first / second ferromagnetic films 35/45. This is because it is added. Further, in the head structure of FIG. 3, the GMR film is patterned, and the track width accuracy is determined by the patterning accuracy.

Next, the flux guide type GMR of the present invention
An example of the head manufacturing method will be described. Although the following thin film forming method and patterning method use the well-known techniques such as the sputtering method, the etching method, and the lift-off method, they can be manufactured by other methods.

First, a 2 μm thick permalloy film to be the lower magnetic shield layer 10 is formed on a non-magnetic substrate, and a 0.1 μm thick alumina film to form the lower gap film 20 is formed thereon. After that, as shown in FIG. 3, a base film 30 of a GMR film is formed on the lower gap film 20, and a conductive first ferromagnetic film 35, a conductive nonmagnetic film 40, and a second ferromagnetic film are formed. 45, an antiferromagnetic film or a permanent magnet film 50 are sequentially laminated by a sputtering method, a vapor deposition method or the like. The laminated film is patterned into a predetermined shape by using an ion milling method. Then, using a lift-off process method, photoresist PI two-layer coating, photoresist PI pattern forming, deep UV cure, antiferromagnetic film or permanent magnet film 50 'by sputtering or vapor deposition method, and conductor film 70 are formed, and photoresist PI is removed. By doing so, the magnetic domain control layer and the electrode are formed. Here, when the conductive antiferromagnetic film is used for the magnetic domain control film 50/50 ′, at least two kinds of conductive antiferromagnetic materials having different blocking temperatures are required because the magnetization vector cannot be controlled when the element is formed with the same material. Is. For example, FeMn, NiM
n, CrMn, etc. are well known. Subsequently, the lower magnetic shield 10 and the lower gap film 20 are patterned into a predetermined shape, and an alumina film forming the upper gap film 80 is formed to a thickness of 0.1 μm. Further, after forming a permalloy film as the upper magnetic shield layer 90 to a thickness of 2 μm,
An alumina protective film is formed, and the GMR head formation is completed. As described above, in the GMR head according to the present invention, since the magnetic domain control film and the electrode film are formed by using the lift-off method, the GMR film is not damaged during the manufacturing process, so that the GMR having good magnetic characteristics is obtained. A film can be formed and a GMR head with stable performance can be manufactured.

The flux guide type GMR head can be expected to have the same effect even with a head structure in which the inductive head shown in FIG. 7 is provided on the substrate side.

Next, an example of a magnetic disk device to which the flux guide type GMR head according to the above embodiment is applied will be described with reference to FIG.

FIG. 8 is a schematic perspective view showing the internal structure of this magnetic disk device.
A disk 203 (one shown in the figure) held by the motor, a motor for driving the spindle 202, a magnetic head 204 held by a movable carriage 205, and a voice coil motor for driving the carriage 205. The base 201 which supports these is provided. Although not shown in the figure, a voice coil motor control circuit for controlling the voice coil motor according to a signal sent from a higher-level device such as a magnetic disk control device is provided.

Further, this device corresponds to the writing method for the data sent from the host device, has a function of converting the data sent to the magnetic head into a current, and amplifies the data sent from the disk 203 to generate a digital signal. A write / read circuit having a function of converting into a signal and an interface are provided.

Next, the operation of the magnetic disk device will be described by taking the case of reading as an example. When an instruction for data to be read is given from the host device to the control circuit via the interface, this device uses the control current from the voice coil motor control circuit to drive the carriage by the voice coil motor and to send the instructed data. The magnetic head group 204 or the like is moved at a high speed to the position of the track where is stored, and the position is accurately positioned. A data surface servo system is used for this positioning. That is, servo information is recorded together with the data on the disk 203, and the positioning accuracy is improved by the servo information. Further, the motor supported by the base 201 rotates a disc 203 having a diameter of 3.5 inches or less attached to the spindle 202. Next, according to a signal from the write / read circuit, a designated predetermined magnetic head is selected, the head position of the designated area is detected, and then the data signal on the disk is read. This reading is performed by the data magnetic head 204 connected to the write / read circuit exchanging signals with the disk 203. The read data is converted into a predetermined signal.

In order to exert the effect of the magnetic head according to the present invention, it is desirable to mount the magnetic head on a magnetic disk device having a track density of 10 k tracks or more per inch.
FIG. 9 shows the change in head sensitivity with respect to the flying height. A magnetic head using a ferromagnetic film showing the soft magnetic characteristics of the free layer constituting the GMR film according to the present invention as a flux guide and a conventionally known flux guide are shown. The characteristics of the formed magnetic head are also shown. The figure shows the relationship between the flying height and the change in sensitivity, and it can be seen that in the magnetic head of the present invention, the smaller the flying height, the lower the sensitivity. This means that the magnetic head using the present invention is suitable for narrow spacing.

[0037]

Of the GMR film formed between the shields,
A ferromagnetic film whose magnetization direction is not fixed is used as a flux guide, and a ferromagnetic film whose magnetization direction is not fixed and a ferromagnetic film whose magnetization direction is fixed are separated by a thin metal layer. A flux guide type GMR head composed of a laminated film or a multilayer film in which the laminated films as one set are further laminated in sequence
A sufficient S / N ratio can be obtained even at a high track density of 0 kTPI or higher, and a highly reliable magnetic disk device that is noise-free can be provided.

Further, in the method of manufacturing the flux guide type GMR head according to the present invention, since the lift-off method is used, the GMR head can be formed without damaging the GMR head during element formation. As a result, the electrical and magnetic properties of the GMR film are not impaired.

[Brief description of drawings]

FIG. 1 is a flux guide type GMR according to an embodiment of the present invention.
The perspective view which shows a head.

FIG. 2 is an enlarged perspective view of a GMR film part according to an embodiment of the present invention.

FIG. 3 is an enlarged perspective view of a magnetic flux change detector of the GMR film.

FIG. 4 is an enlarged perspective view showing another embodiment of the magnetic flux change detection unit of the GMR film.

FIG. 5 is a diagram showing the relationship between the magnetic coupling and the non-magnetic film thickness of the GMR film that constitutes the present invention.

FIG. 6 is a schematic diagram for explaining the function of the magnetic domain control layer of the GMR film.

FIG. 7 is a perspective view showing another embodiment of the flux guide type GMR head of the present invention.

FIG. 8 is an internal schematic diagram of a magnetic disk device using the flux guide type GMR head of the present invention.

FIG. 9 is a diagram showing the relationship between head sensitivity and flying height.

[Description of Reference Signs] 10 ... Lower magnetic shield film, 20 ... Lower gap film, 35, 104 ... Ferromagnetic film showing soft magnetic characteristics of the first free layer, 40 ... Conductive non-magnetic film, 45 ... Second Ferromagnetic film whose magnetization vector is fixed, 50 ... Antiferromagnetic film or permanent magnet film, 50 '... Antiferromagnetic film or permanent magnet film for applying a longitudinal bias magnetic field, 70 ... Signal detection electrode, 8
0 ... upper gap film, 90 ... upper magnetic shield film, 1
00 ... Flux guide, 102 ... Base metal film, 11
0 ... upper magnetic core for write head, 201 ... base,
202 ... Spindle, 203 ... Disc, 204 ... Magnetic head, 205 ... Carriage.

Claims (8)

[Claims] 1. A read head comprising a write head on a substrate and a multi-layered film of a ferromagnetic film and a non-magnetic film and a magnetic domain control film between shields, and a magnetic field from a recording medium is induced to the read head. In the magnetic head having the flux guide on the medium facing surface as described above, the film thickness of the flux guide is smaller than the film thickness of the read head. 2. A read head comprising a write head on a substrate and a multilayer film of a ferromagnetic film and a non-magnetic film and a magnetic domain control film between shields, and a magnetic field from a recording medium is induced to the read head. In the magnetic head having the flux guide on the medium facing surface as described above, the flux guide provided on the medium facing surface is composed of a part of a ferromagnetic film of a multilayer film forming the read head. GMR head. 3. The flux guide type GMR head according to claim 1, wherein the ferromagnetic film forming the flux guide is formed on a base metal film of a multilayer film forming the read head. 4. A magnetization control film constituting the read head, wherein as the magnetization control film, a combination of at least one of a permanent magnet film and an antiferromagnetic film, or two or more permanent magnet films having different coercive forces. The flux guide type GMR head according to claim 1, wherein the combination or two or more kinds of conductive antiferromagnetic films having different blocking temperatures are used. 5. The ferromagnetic film forming the read head is
The flux guide type GMR head according to claim 1, wherein the flux guide type GMR head is made of a magnetic alloy containing at least one of Fe, Co and Ni. 6. The non-magnetic film constituting the read head separates a ferromagnetic layer, and the non-magnetic film is silver, copper, gold, and an alloy of two or more kinds thereof or a laminated film of each of them. The flux guide type GMR head according to claim 1, wherein 7. The flux guide type GM according to claim 1, wherein the ferromagnetic film thickness and the non-magnetic film thickness of the read head are 5 Å or more and 100 Å or less.
R head. 8. A flux guide type G according to claim 1 or 2.
A magnetic disk device equipped with an MR head, comprising:
A magnetic disk device having a track density of kTPI or more.