JP2001034916A - Composite thin film magnetic head and storage comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the so-called popcorn noise which is a spike-like random noise component appearing in a reproduction output immediately after a recording operation by forming an upper magnetic shielding layer comprising a first magnetic shielding layer, with a thickness in a specific range, close to a magneto-resistance effect sensor for reproduction and a second magnetic shielding layer deposited onto the first magnetic shielding layer. SOLUTION: An upper magnetic shielding layer 16 is composed of a portion (underlying film) 16a (first magnetic shielding layer) close to an MR sensor section 14 and the other portion (upper magnetic shielding layer portion) 16b (second magnetic shielding layer) than the underlying film 16a of the upper magnetic shielding layer 16, and the thickness of the underlying film 16a is in the range from 0.1 μm to 1.0 μm. Permalloy containing nickel(Ni) and iron as its main components is used as the underlying film 16a, and the underlying film 16a is deposited by sputtering to achieve a desired thickness and magnetostriction constant. It is desirable that the composition of Ni in the underlying film 16a is in the range from 81.5% to 85% and the magnetostriction constant of the underlying film 16a is in the range from 0 to -5×10-6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite thin-film magnetic head in which a recording magnetic head and a reproducing magnetic head are combined for use in a magnetic disk drive or the like, and a storage device using the same.

[0002]

2. Description of the Related Art In recent years, with the increase in the recording density of magnetic disk devices and the like, the recording operation has been replaced with an inductive type magnetic head for both recording and reproduction. A combined read / write thin-film magnetic head (hereinafter abbreviated as MR head) using an (MR) sensor has been used.

In order to read data recorded on a magnetic recording medium, the magnetoresistive sensor portion of the MR head has two
It must be arranged between two magnetic shield layers. These magnetic shield layers are called a lower shield layer, an upper shield layer and a lower magnetic core. US Patent No. 4639
No. 806 discloses an MR head including a magnetoresistive sensor portion disposed between two magnetic shield layers. Further, the same publication discloses that NiZn (nickel / zinc) ferrite, MnZn
(Manganese / zinc) ferrite, FeAlSi (iron / aluminum / silicon) commonly called sendust
Alloys and NiFe commonly called permalloy
It is disclosed that it is made of a magnetic material having a high magnetic permeability, such as a (nickel / iron) alloy.

Japanese Patent Application Laid-Open No. Sho 59-90222 discloses that an amorphous magnetic film is used as a magnetic shield layer of an MR head. It is disclosed that both the magnetic permeability and the saturation magnetic flux density have characteristics superior to those of the conventional shield layer material.

In a conventional inductive magnetic head for both recording and reproduction, when the reproduction output is measured immediately after the recording operation, a spike-like random noise component often called popcorn noise or post-write noise often appears. is there. Since the same magnetic core is used for recording and reproduction, the magnetic moment of the magnetic core largely moved by the recording magnetic field becomes a metastable state before returning to the original state, and then returns to the original state. It is understood that such noise appears when returning with a certain time delay.

In a conventional inductive magnetic head for both recording and reproduction, the stress applied during the process of the magnetic core and the magnetic characteristics of the magnetic core are controlled to change the composition of Fe (iron) and Ni (nickel), for example. The generation of such popcorn noise is suppressed by adding impurities or adding impurities.

In the combined read / write thin film magnetic head, an inductive magnetic head for recording and a magnetoresistive (MR) sensor for reproduction are divided into an upper magnetic shield corresponding to the magnetic head for recording and an upper magnetic recording head. It has been considered that the generation of popcorn noise can be suppressed by controlling the magnetic characteristics of the magnetic core, including the magnetostriction constant, as in the inductive type magnetic head for both recording and reproduction.

[0008]

However, according to the investigation and research conducted by the present inventors, the magnetic instability in the area of the upper magnetic shield which is closer to the MR sensor is a source of such popcorn noise. It became clear that. Therefore, it has been found that the generation of such popcorn noise cannot be suppressed only by controlling the magnetic characteristics of the entire upper magnetic shield.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to reduce a spike-like random noise component called popcorn noise which appears in a reproduced output immediately after performing a recording operation, and a composite thin-film magnetic head therefor. And a storage device using the same.

[0010]

In order to achieve the above object, the present invention eliminates magnetic instability in the area of the upper magnetic shield near the MR sensor.
In order to achieve the above object, the present invention suppresses popcorn noise by using two layers of upper magnetic shields and controlling the magnetic characteristics of a portion near the MR sensor so that popcorn noise is reduced.

According to the present invention, the recording operation is performed by making the upper magnetic shield layer of the read / write separated composite type thin film magnetic head two layers and optimizing the film thickness, composition, and magnetic characteristics on the side near the MR sensor. The magnetic moment of the upper magnetic shield, which is greatly moved by the magnetic field when it is performed, does not have a time delay in the festival that returns to the original state, so that it appears in the reproduced waveform immediately after the recording operation commonly called popcorn noise A magnetic head in which spike-like random noise components are suppressed can be provided.

In order to achieve the object of the present invention, a composite thin-film magnetic head according to the present invention comprises a lower magnetic shield layer, a magnetoresistive sensor for reproduction, an upper magnetic shield layer, an upper magnetic core for recording, and a recording operation. In a composite type thin film magnetic head comprising a magnetic coil, the upper magnetic shield layer is formed on a first magnetic shield layer close to the reproducing magnetoresistive sensor and a second magnetic shield formed on the first magnetic shield layer. And wherein the first magnetic shield layer has a thickness of 0.1 μm to 1.0 μm.

It is preferable that the first magnetic shield layer is made of permalloy containing nickel and iron as main components and the first magnetic shield layer is formed by a sputtering method to obtain a desired composition and magnetostriction constant. It is. Further, it is preferable that permalloy containing nickel and iron as main components is used for the first magnetic shield layer, and the nickel composition is in the range of 81.5% to 85%.

It is preferable that permalloy containing nickel and iron as main components is used for the first magnetic shield layer, and the magnetostriction constant is in the range of 0 to −5 × 10 ⁻⁶ . In order to achieve the object of the present invention, a storage device according to the present invention comprises:
A lower magnetic shield layer, a magnetoresistive sensor for reproduction, an upper magnetic shield layer, an upper magnetic core for recording, and a magnetic coil for recording operation, wherein the upper magnetic shield layer is a first magnetic layer close to the magnetoresistive sensor for reproduction. And a second magnetic shield layer formed on the first magnetic shield layer, wherein the thickness of the first magnetic shield layer is 0.1 μm to 1.0 μm. A magnetic head is used, and information is stored on a magnetic disk by the composite magnetic head.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a composite thin-film magnetic head according to the present invention and a storage device using the same. FIG. 1 is a perspective view, partly in section, showing one embodiment of a combined read / write thin film magnetic head according to the present invention. FIG. 1 is a bird's-eye view of the head viewed obliquely from above. The composite thin-film magnetic head has a substrate 10, a base film layer 11, a lower magnetic shield layer 12, an insulating layer 13, an MR sensor unit 14, and a hard bias layer 2.
0, an electrode layer 15, an upper magnetic shield layer 16, an organic insulating film layer 17, an exciting coil 18, an upper magnetic core 19 for writing, and the like. The hard bias layer 20 is made of, for example, a permanent magnet and makes the direction of magnetization of the MR sensor unit 14 constant.

In FIG. 1, the difference from the conventional magnetic head is that the upper magnetic shield layer 16 has a portion 16a close to the MR sensor (hereinafter referred to as a base film 16a) and other portions 16.
b (hereinafter referred to as the upper magnetic shield layer portion 16b)
It is divided into layers. At present, a permalloy alloy is often used for the upper magnetic shield layer portion 16b.
When this permalloy film is formed on an MR or GMR head, it is general to form the film by plating.

The upper magnetic shield layer 16b is formed by plating.
When forming a film, various metals are used for the conductive base film 16a, but recently, a permalloy alloy similar to the plating film is generally used, and is formed by a sputtering method. At this time, in order to reduce the magnetic effect of the underlying film 16a on the upper magnetic shield layer portion 16b as much as possible, the underlying film 16a is often formed with a thickness of less than 0.1 μm.

In the present invention, on the contrary, the thickness of the base film 16a is set to 0.1 μm or more, and the film composition in the vicinity of the MR sensor is controlled by using a sputtering method excellent in controllability of the film composition. It is possible to provide a stable recording / reproducing separation type composite thin film magnetic head by eliminating the magnetic instability of the nearby shield layer.

In order to reduce the popcorn noise, it is necessary to stabilize the magnetostriction constant of the magnetic shield layer near the MR sensor, especially the underlayer 16a and the upper magnetic shield layer portion 16b. When the thickness of the underlayer 16a is less than 0.1 μm, the magnetostriction constant is determined by the upper magnetic shield layer portion 16b.
When the thickness of the base film 16a is 0.1 μm or more, the base film 16a
, The magnetostriction constant can be controlled by controlling the composition of the base film 16a. Further, when the entire shield is formed by a sputtering method by increasing the thickness of the base film itself, the thickness is limited to about 1 μm even if the thickness can be increased due to a rise in temperature during film formation and other problems. Therefore, in this embodiment, the thickness of the base film 16a is set to 0.1 μm to
1 μm, and the base film 16a is formed by sputtering.
To control the composition of

FIG. 2 is a characteristic diagram showing the Ni composition of the permalloy base film and the generation rate of popcorn noise. In the figure, the abscissa indicates the weight% NiWP of the Ni composition of the underlayer,
The vertical axis shows the popcorn noise occurrence rate PG. This graph shows that a magnetic head in which the thickness of the underlayer is 0.3 μm and the weight percentage of Ni is changed is manufactured, and writing and reading are repeated a predetermined number of times with this head. The occurrence rate was calculated by checking whether or not the occurrence occurred.

According to FIG. 2, the Ni composition is 81.5%
It can be seen that the popcorn noise occurrence rate sharply rises below. It is also known that when the Ni composition is set to 85% or more, not popcorn noise but unstable factors such as waveform fluctuation and Barkhausen noise appear. Therefore, the Ni composition of the base film 16a is 82% to 85%.
It is desirable to control between%.

FIG. 3 is a characteristic diagram showing the percentage of defective popcorn noise with respect to the magnetostriction constant of the underlying film. In the figure,
The horizontal axis represents the magnetostriction constant MD (× 10 ⁻⁶ ) of the underlayer,
The vertical axis indicates the popcorn noise occurrence rate PG (%).
There is a close relationship between the composition of permalloy and the magnetostriction constant.
When the i composition increases, the magnetostriction constant moves in a negative direction, and when the Ni composition decreases, the magnetostriction constant moves in a positive direction. Therefore, when viewed in terms of the magnetostriction constant, the popcorn noise generation rate appears to be stable in the range of 0 to −5 × 10 ^−6. Thus, when the magnetostriction constant of the base film is different, the upper magnetic shield layer portion 16a has In order to find out what is happening, the Kerr on the surface of the upper magnetic shield layer portion 16a
The magnetic domain structure was observed by the effect. The result was photographed using an optical microscope, and the photograph is schematically shown in FIG. FIG. 4 is a diagram showing a magnetic domain structure in an upper magnetic shield layer portion, and FIG. 4A is a diagram showing a magnetic domain structure when a magnetoresistive effect type magnetic head according to the present invention is used, and FIG. FIG. 3 is a diagram showing a magnetic domain structure when a conventional magnetoresistive head is used. In the sample of FIG. 4A, the magnetostriction constant is within an appropriate range, and no particular disturbance is observed in the magnetic domain structure. However, in the sample of FIG. 4B, the magnetostriction constant is out of the appropriate range. It can be seen that the magnetic domain structure disturbances 40a and 40b are generated in a part. When a recording operation is performed due to such disturbances 40a and 40b of the magnetic domain structure, the upper magnetic shield layer portion 1
It can be understood that the magnetic moment of 6b is largely moved by the magnetic field at the time of recording, and has a time delay in the festival of returning to the original state, generating a spike-like random noise called popcorn noise.

As is apparent from the above, the base film 1
By setting the thickness of the film 6a to 0.1 μm to 1.0 μm, the composition of the base film 16a can be controlled to reduce popcorn noise. By adopting a sputtering method for forming the base film 16a, the base film 16a is formed.
The Ni composition of a can be controlled more accurately. In the embodiment of the present invention, the Ni composition is 81.
It has been found that a range of 5% to 85% is preferable. In the embodiment of the present invention, the magnetostriction constant is set to 0 to 5 × 1.
It has been found that a value of 0 ^-6 is preferable.

In the present invention, a storage device with reduced popcorn noise can be obtained by employing the above-described composite thin film magnetic head in a storage device such as a magnetic disk device.

[0025]

As described above, according to the present invention, a magnetic head which suppresses spike-like random noise components appearing in a reproduced waveform immediately after a recording operation, which is generally called popcorn noise, and a storage device using the same are obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a partially sectional perspective view showing an embodiment of a combined read / write thin film magnetic head according to the present invention.

FIG. 2 is a characteristic diagram showing a Ni composition of a permalloy base film and an occurrence rate of popcorn noise.

FIG. 3 is a characteristic diagram illustrating a defect rate of popcorn noise with respect to a magnetostriction constant of a base film.

FIG. 4 is a diagram showing a magnetic domain structure in an upper magnetic shield layer portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Substrate, 11 ... Base film layer, 12 ... Lower magnetic shield layer, 13 ... Insulating layer, 14 ... MR sensor part, 15 ... Hard bias layer and electrode layer, 16 ... Upper magnetic shield layer, 16a ... Upper magnetic shield layer Of the side close to the MR sensor section (underlying film), 16b... Other than the upper magnetic shield layer section 16a (upper magnetic shield layer section), 1
7: Organic insulating film layer, 18: Exciting coil, 19: Upper magnetic core for writing.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuichi Kojima 2880 Kozu, Kozuhara-shi, Kanagawa Prefecture Inside the Hitachi, Ltd.Storage Systems Division (72) Koji Okazaki 2880 Kozu, Kozu, Odawara-shi, Kanagawa Storage Hitachi, Ltd. Within System Division (72) Inventor Kenji Ishikake 2880 Kozu, Odawara-shi, Kanagawa Prefecture F-term within Storage Systems Division, Hitachi, Ltd. 5D034 BA21 BB02 BB09 BB12 CA04

Claims (5)

[Claims] 1. A composite thin-film magnetic head comprising a lower magnetic shield layer, a magnetoresistive sensor for reproduction, an upper magnetic shield layer, an upper magnetic core for recording, and a magnetic coil for recording operation, wherein the upper magnetic shield layer is A first magnetic shield layer close to the magnetoresistive sensor for reproduction;
And a second magnetic shield layer formed on the magnetic shield layer having a thickness of 0.1 μm.
A composite thin-film magnetic head having a thickness of 1.0 to 1.0 μm. 2. A composite thin-film magnetic head according to claim 1, wherein said first magnetic shield layer is made of permalloy containing nickel and iron as main components, and said first magnetic shield layer is formed by sputtering. A composite type thin film magnetic head characterized in that a desired composition and magnetostriction constant are obtained by forming a film. 3. The composite thin-film magnetic head according to claim 1, wherein the first magnetic shield layer is made of permalloy containing nickel and iron as main components, and has a nickel composition of 8%.
A composite thin-film magnetic head having a range of 1.5% to 85%. 4. A composite thin film magnetic head according to claim 1, wherein said first magnetic shield layer is made of permalloy containing nickel and iron as main components, and has a magnetostriction constant of 0 to -5.
A composite thin-film magnetic head characterized by being in the range of × 10 ^-6 . 5. A magnetoresistive effect for reproduction comprising a lower magnetic shield layer, a magnetoresistive sensor for reproduction, an upper magnetic shield layer, an upper magnetic core for recording, and a magnetic coil for recording operation. A first magnetic shield layer close to the sensor; and a second magnetic shield layer formed on the first magnetic shield layer, wherein the thickness of the first magnetic shield layer is 0.1 μm to 1.0 μm. Using a composite thin film magnetic head to be, by the composite magnetic head,
A storage device for storing information on a magnetic disk.