JPH08241504A - Magnetoresistance effect type magnetic head - Google Patents

Abstract

PURPOSE: To obtain a magnetic head having high output by providing a magnetoresistance effect film, a bias film, a pair of electrodes and a magnetic domain controlling film for controlling the magnetic domains of the bias film and making the bias film longer than the magnetoresistance effect film and effective reproduction track width smaller than geometric track width. CONSTITUTION: An upper shielding film 80 and a lower shielding film 10 prevent a magnetic field other than a signal from affecting a magnetoresistance effect film 40 and enhance the signal resolving power of a magnetoresistance effect type head 1000. The material of each of the films 80, 10 is a soft magnetic material such as an NiFe alloy, an NiCo alloy or an amorphous Co alloy and the thickness is 0.5-3μm. An upper gap film 70 and a lower gap film 20 disposed in adjacent to the magnetic shielding films 80, 10, respectively, act to electrically and magnetically isolate a magnetoresistance effect element from the films 80, 10 and each of the gap films 70, 20 is made of a nonmagnetic insulating material such as glass. In order to transduce a magnetic signal from a magnetic disk into a linear electric signal, a separating film 50 and a bias film 55 are disposed so that a transverse bias magnetic field is applied to the magnetoresistance effect film 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device for magnetically storing information, and more particularly to a magnetic disk device for reproducing information by utilizing a magnetoresistive effect.

[0002]

2. Description of the Related Art When information is reproduced by utilizing the magnetoresistive effect, the track width of a magnetic head is about several micrometers because of high recording density. When such a minute magnetoresistive film pattern is used, there is a problem that the reproduction signal of the magnetic head is distorted. Journal of Applied Physics, 1981, 52, 2465 (J. Appl. Phys. 52 2465.
1981) shows that the phenomenon in which the signal of the reproducing magnetic head to which the magnetoresistive effect film is applied is distorted irregularly is due to the domain wall formed in the magnetoresistive effect film. This phenomenon is called Barkhausen noise. From this, it is found that eliminating the domain wall from the magnetoresistive film (referred to as single domain formation) is effective in reducing strain. The following are conventional methods for forming a single magnetic domain.

In Japanese Patent Laid-Open No. 3-125311, a magnetic sensor film composed of a magnetoresistive film, a bias film and a film for separating them is miniaturized to a size of a reproduction track width by ion etching and integrated with an electrode. A method of making the magnetoresistive film into a single magnetic domain with the permanent magnet film is disclosed. This technique forms a two-layer mask resist having a size of a reproduction track width on a multilayer film of a magnetoresistive film, a separation film, and a bias film, and removes unnecessary multilayer film portions by using ion etching. Form the electrode film as it is,
After that, the resist is removed. The head having the same structure is characterized in that the geometrical track width, that is, the length of the magnetoresistive film measured from the surface facing the recording medium, and the reproducing track width of the head, that is, the width having effective reproducing sensitivity, are substantially the same. . From this, the head of the same structure is 1
It is excellent as a head to be mounted on a magnetic recording device having a recording density of 3000 to 8000 tracks per inch. However, in order to further increase the track density, it is required to narrow the track of the magnetic head. The following problems occur when a head having a track width of 2 μm or less is realized by the above conventional technique.

[0004]

The two-layer resist used for etching the magnetoresistive film has an undercut that causes the lower layer to recede from the upper layer. This is to prevent reattachment during ion etching, control of etching shape, and This is important for controlling the electrode shape. According to the studies made by the present inventors, it has been found that the amount of undercut needs to be 0.5 μm or more, and if it is less than that, it cannot be controlled or the shape of each part cannot be stabilized. Therefore, when the head is made narrower than 2 μm due to the request, the above-mentioned prior art cannot stably form the geometrical track width due to the limitation of the undercut width, and the geometrical width of 1 μm or less is not possible. It turns out that the track width cannot be realized.

Therefore, an object of the present invention is to provide a technique for forming a narrow track magnetic head that can be mounted on a magnetic disk device when the recording density is improved, and to realize a magnetic disk device compatible with high recording density. There is.

[0006]

The magnetic head of the present invention comprises:
A magnetoresistive film, a bias film, a pair of electrodes, and a magnetic domain control film for controlling the magnetic domains of the bias film. In particular, the bias film is longer than the magnetoresistive film and the effective reproduction track width is a geometric track. It is characterized by being smaller than the width.

The magnetic head of the present invention comprises a magnetoresistive effect film, a bias film, a pair of electrodes, and a magnetic domain control film for controlling the magnetic domain of the bias film. It is long and has a structure in which the bias film and the magnetic domain control film are separated by a magnetoresistive effect film, and is characterized in that the effective reproducing track width is smaller than the geometric track width by 0.3 μm or more.

Further, the magnetic head of the present invention comprises a magnetoresistive effect film, a bias film, a pair of electrodes, and a magnetic domain control film for controlling the magnetic domain of the bias film. It is long and has a structure in which the bias film and the magnetic domain control film are separated by a magnetoresistive film, and is characterized in that a hard magnetic film such as a permanent magnet film or an exchange coupling bias film is provided below the electrodes.

Further, the magnetic head of the present invention comprises a magnetoresistive effect film, a bias film, a pair of electrodes, and a magnetic domain control film for controlling the magnetic domain of the bias film. It is characterized in that a long magnetic domain control film that mainly fixes only the end magnetization of the bias film is provided between the bias film and the electrode film.

[0010]

In the magnetoresistive head according to the present invention, the bias film is mainly domain-controlled in order to suppress Barkhausen noise which is a distortion of the reproduced waveform. This structure has the following features. In the above-mentioned known example, the demagnetizing field is reduced in the track width direction by exchange-coupling the end portion of the magnetoresistive film and the permanent magnet film, and the track width direction is substantially an easy axis of shape anisotropy. While the entire resistance effect film acts as a magneto-sensitive part, in the present invention, the shape anisotropy of the magneto-resistive film at the center of the magneto-sensitive part is substantially equal due to the demagnetizing field generated at the end of the magneto-resistive film. It becomes directional and the sensitivity increases.
Further, the end portion becomes a dead zone because the magnetization of the magnetoresistive effect film is parallel to the end portion and does not rotate easily, and the effective reproduction track width becomes narrower than the width of the magnetoresistive effect film of the magnetic sensitive portion. That is, a high-output magnetoresistive head having a smaller width than the geometrical reproduction track width can be realized.

Further, the effective reproduction track width can be adjusted to an optimum design value by providing a permanent magnet film on a bias film which is irrelevant to the bias action and adjusting the width of the dead zone with the magnetic field generated. It is possible. By setting the product of the film thickness of the permanent magnet and the magnetic flux density to about 1.6 times that of the magnetoresistive film, the dead zone is reduced to about 0.15 μm, but even if the dead zone is made thicker, this value does not change.

The magnetic domain control film used in the present invention is equal to or rather long than the bias film, and extends over the entire magnetic sensitive portion. Therefore, if a metal antiferromagnetic film such as FeMn or a metal ferromagnetic film such as CoPt is used for this, the sense current is shunted to this portion, the resistance change amount of the magnetoresistive film is diluted, and the sensitivity is lowered.
Therefore, it is preferable to use an oxide-based antiferromagnetic film such as NiO or an oxide-based ferromagnetic film such as Fe2O3 for the magnetic domain control film.

[0013]

EXAMPLES Examples of the present invention will be described below.

Upper shield film, lower shield film 80, 1
0 acts to prevent the magnetic resistance effect film 40 from being affected by a magnetic field other than a signal, and to increase the signal resolution of the magnetoresistive effect head 1000. The material is NiFe alloy, N
iCo alloy, Co-based amorphous alloy and other soft magnetism,
The film thickness is about 0.5 to 3 μm.

An upper gap film and a lower gap film 7 which are arranged adjacent to the magnetic shield films 80 and 10.
0 and 20 act to electrically and magnetically isolate the magnetoresistive element from the upper and lower shield films 80 and 10.
It is made of non-magnetic insulating material such as glass or alumina.
A portion between the pair of signal detection electrodes 60 is referred to as a magnetic sensing portion, and a signal is read from the magnetic disk at this portion. In order to convert the magnetic signal from the magnetic disk into a linear electric signal, a separation film 50 and a bias film 55 are placed to apply a lateral bias magnetic field to the magnetoresistive film 40. Magnetoresistive film 4
0 is formed of a ferromagnetic film such as a NiFe alloy, a NiCo alloy, or a NiFeCo alloy whose electric resistance changes depending on the direction of magnetization. The film thickness is about 0.01 μm to 0.
It is 045 μm.

Since the signal detection electrode 60 allows a sufficient current to flow through the magnetoresistive film 40, for example, 1 × 10 ^{6 to} 3 × 10 ⁷ A / cm 2, it usually has Cu, Au, Nb,
A thin film such as Ta or W is used.

In the soft film bias method, a ferromagnetic film having soft magnetic characteristics is formed adjacent to the magnetoresistive film via a non-magnetic layer, and a magnetic field generated by a current flowing through the magnetoresistive film is efficiently used. Often, it is a method of applying to the magnetoresistive film. As the bias film 55, NiFeRu, N
A soft magnetic material such as iFeNb, NiFeRh, and CoZrCr, which has a high electric resistance and a saturation magnetic flux density as large as possible, is used. Therefore, it is also called a soft film. These are used by laminating the magnetoresistive film 40, the separation film 50 (nonmagnetic film), and the bias film 55 as shown in FIG.

CoPt, CoPtCr, CoCrTa, Fe 2 is formed on the magnetic domain control film 30.
Either a permanent magnet film such as O3 or an antiferromagnetic film such as NiO, FeMn, NiMnCr, or a combination thereof is applied. However, when a metal-based material is used for the magnetic domain control film, the sense current is shunted to the same portion and the head sensitivity is lowered. Therefore, if possible, a material having a specific resistance from a semiconductor to an insulator, such as an oxide, is preferable. It is preferable to apply the NiO antiferromagnetic film from the viewpoint of easiness.

The underlayer film 35 separates the magnetic coupling between the magnetic domain control film and the magnetoresistive effect film, and is preferably made of a high resistance material from the viewpoint of the shunt ratio, and Ta in order to improve the crystallinity of the magnetoresistive effect film. Is desirable.

Next, a method of manufacturing the magnetoresistive head 1000 will be described. The thin film forming method and patterning method described below used a sputtering method, an etching method, and a photolithography method.

FIG. 2 shows the main part of a specific manufacturing method below. The figure shows a cross-sectional view of a position where the magnetoresistive head is to be the medium facing surface after the air bearing surface processing. First, a NiFe alloy to be the lower shield film 10 is formed, and then alumina to be the lower gap film 20 is formed on the NiFe alloy. Then, the lower shield film 10 and the lower gap film 20
And are processed into a predetermined shape (a). Next, the lower gap film 2
An oxide antiferromagnetic film 30 of 0.04 to 0.15 μm is formed on the upper side of 0. The oxide film having a magnetic domain control effect is preferably a ferromagnetic film or an antiferromagnetic film, but antiferromagnetic nickel oxide (NiO) is preferable in terms of stability against an external magnetic field, blocking temperature, and ease of production. As the material of the oxide antiferromagnetic film 45, in addition to the above NiO, hematite (α-Fe2
It can be estimated that O3 can be substituted. Furthermore, NiO to F
e, Co, Ni magnetic elements and rare earth magnetic elements La, C
e, Pr, Nd, Pm, Sm, Gd, Tb, Dy, H
It is also possible to substitute by adding o, Er, Tm, and Yb.

A two-layer resist frame is formed on the magnetic domain control film (b), Ta5 nm as the underlayer film 35, Permalloy 20 nm as the magnetoresistive film 40, and Ta5 nm as the separation film 50 are sequentially formed, and lift-off is performed, as shown in FIG. Such a pattern is formed. A NiFeNb film is formed as a bias film on this by sputtering, and then the element height direction is processed by ion etching parallel to the paper surface (d). After that, a frame that determines the geometrical track width is formed by a two-layer resist (e). The upper layer resist 110 is 2 μm wide, and the lower layer resist 11
The width of 1 was set to 1 μm width by taking into account 0.5 μm on one side. A three-layer film of Ta / Au / Ta is formed on this, and lift-off is performed to obtain the electrode shape of f).

Thereafter, the upper magnetic shield film 80, N, is formed.
An iFe alloy film is formed to a thickness of 2 μm, an alumina film 90 to be a recording gap of the upper write head is formed to 0.5 μm, a write head coil and an interlayer insulating film are formed, and then a write head 95 is formed of a NiFe alloy. . The width of the write head 95 corresponds to the recording track width,
It was set to micrometer. After that, alumina is formed to a thickness of 20 μm as a protective film, and the magnetoresistive head 1
000 is completed.

The head of the present invention has a geometric track width of 2
It is possible to provide a high-sensitivity and noise-free magnetoresistive magnetic head having an effective track width narrower than a micrometer.

The reproducing track profile of the magnetoresistive head according to the present invention is shown in FIG. The drawing is a plot of the signal intensity and the head position read by moving the head on a micro track formed by erasing a signal written by the head 1000 by a minute amount and erasing at a different frequency. For comparison, the track profile of the head 1100 formed with the same geometric reproduction track width using the method of the above-mentioned known example is also shown. Since the integrated intensity of the profile in the figure is the head reproduction output, the two outputs are almost the same. However, the effective track width is 10
00 is 1.4 μm, head 1100 is 1.9 μm, and head 1000 can realize a narrower reproduction track width. In order to realize 1.4 μm in the structure of the head 1100, the lower layer of the double-layer resist should be 0.4 μm, but the lower-layer resist of such width is not dimensionally stable, and resist peeling and distortion may occur. It has been confirmed that it becomes a cause and cannot be put to practical use. Further, in the head in which the CoCr film 40 nm is previously formed when the electrode 60 of the head 1000 is formed, the effective track width is 1.6 nm, and the track width can be changed without changing the mask dimension.

[0026]

According to the present invention, it is possible to realize a magnetoresistive effect magnetic head for high density magnetic recording, which is capable of noiseless and high output.

[Brief description of drawings]

FIG. 1 is a perspective view showing a magnetoresistive effect magnetic head according to an embodiment of the present invention. And a cross-sectional view.

FIG. 2 is a schematic view of a head manufacturing process of the present invention.

FIG. 3 shows an example of effective track width measurement of the head of the present invention.

[Explanation of symbols]

1 ... Substrate, 10 ... Lower shield film, 20
... Lower gap film, 40 ... Magnetoresistive film, 30 ... Domain control film, 50 ... Separation film, 55 ... Bias film,
60 ... Signal detection electrode, 70 ... Upper gap film,
80 ... Upper shield film, 95 ... Recording head upper magnetic core, 90 ... Recording head gap, 1000 ... Magnetoresistive magnetic head, 101 ... Upper resist width,
111 ... Lower resist width, Wcd ... Effective track width.

Claims (4)

[Claims] 1. A magnetoresistive effect film for converting a magnetic signal into an electric signal by using a magnetoresistive effect, a bias film for applying a bias to the magnetoresistive effect film, and a signal detection current for the magnetoresistive effect film. And a magnetic domain control film for controlling the magnetic domain of the bias film, wherein the bias film is longer than the magnetoresistive film and the effective reproduction track width is smaller than the geometric track width. And a magnetoresistive effect type magnetic head. 2. A magnetoresistive effect film for converting a magnetic signal into an electrical signal by using a magnetoresistive effect, a bias film for applying a bias to the magnetoresistive effect film, and a signal detection current for the magnetoresistive effect film. And a magnetic domain control film for controlling the magnetic domain of the bias film, wherein the bias film is longer than the magnetoresistive film and the bias film and the magnetic domain control film are separated by the magnetoresistive film. A magnetoresistive head having a structure and having an effective reproducing track width smaller than a geometric track width by 0.3 μm or more. 3. A magnetoresistive effect film for converting a magnetic signal into an electric signal by using a magnetoresistive effect, a bias film for applying a bias to the magnetoresistive effect film, and a signal detection current for the magnetoresistive effect film. And a magnetic domain control film for controlling the magnetic domain of the bias film, wherein the bias film is longer than the magnetoresistive film and the bias film and the magnetic domain control film are separated by the magnetoresistive film. A magnetoresistive effect magnetic head having a structure, wherein a hard magnetic film such as a permanent magnet film or an exchange coupling bias film is provided below the electrodes. 4. A magnetoresistive effect film for converting a magnetic signal into an electric signal by using a magnetoresistive effect, a bias film for applying a bias to the magnetoresistive effect film, and a signal detection current for the magnetoresistive effect film. And a magnetic domain control film for controlling the magnetic domain of the bias film, and in particular, the bias film is longer than the magnetoresistive film and mainly fixes only the end magnetization of the bias film. Is provided between the bias film and the electrode film.