JP2000268329A - Composite thin-film magnetic head and magnetic disk drive - Google Patents

Abstract

(57) Abstract: A highly reliable composite thin-film magnetic head and magnetic disk device that reproduce magnetic recording signals well and reduce the occurrence of waveform distortion and noise are provided. A magnetoresistive head provided with a base material and a magnetoresistive sensor, and an inductive head formed by laminating a thin film on the magnetoresistive head;
A magnetoresistive sensor 19 having a length of 0.5 to 1 μm in a direction perpendicular to a surface facing a recording medium in a composite thin-film magnetic head having 7, 9, 10 and a protective film 11; The length perpendicular to the surface facing the recording medium is 200 to 300 μm, and the film thickness is 10 to 20 μm.
and a protective film 11 having a thickness of μm.

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 and a magnetic disk drive in which recording is performed by an inductive head utilizing electromagnetic induction of a coil and reproduction is performed by a magnetoresistive head, and particularly, the reliability thereof is improved. It is suitable for enhancing.

[0002]

2. Description of the Related Art Conventionally, in order to reduce the internal stress of a protective film of a thin film magnetic head as a whole to form a head element substrate without warpage and to improve magnetic characteristics, alumina having a compressive intrinsic stress and tensile It is known that silicon having intrinsic stress is alternately laminated a plurality of times.
No. 12625.

[0003]

In the above-mentioned prior art, since different types of films are alternately stacked a plurality of times, not only a great number of man-hours are required but also a composite type thin film magnetic head in which reproduction is performed by a magnetoresistive head. In the case of a head, a reproduction error of a magnetic recording signal, noise, or the like occurs, and there is a possibility that the reliability is impaired.

An object of the present invention is to provide a highly reliable composite thin film magnetic head and a magnetic disk drive which solve the above-mentioned problems, reproduce a magnetic recording signal well, and reduce the occurrence of waveform distortion and noise. It is in.

[0005]

In order to achieve the above object, the present invention provides a magnetoresistive head provided with a base material and a magnetoresistive sensor, and laminating a thin film on the magnetoresistive head. In the composite type thin-film magnetic head having the inductive head constituted by the above and a protective film for protecting the inductive head, the length in the direction perpendicular to the surface facing the recording medium is 0.5 to 1 μm.
And a length in a direction perpendicular to a surface facing the recording medium is 200 to 300 μm,
And a protective film having a thickness of 10 to 20 μm.

As a result, the inductive head can be sufficiently protected, and the intrinsic stress of the protective film can be reduced, so that the influence on the magnetic characteristics of the magnetoresistive head can be neglected. Can be reduced and reliability can be improved.

In the above, it is desirable that the protective film is made of alumina.

Further, the present invention provides a composite type including a magnetoresistive head provided with a base material and a magnetoresistive sensor, and an inductive head formed by laminating a thin film on the magnetoresistive head. In the thin-film magnetic head, a magnetoresistive sensor whose length in a direction perpendicular to the surface facing the recording medium is approximately 1 μm, and which protects the inductive head and is perpendicular to the surface facing the recording medium. The protective film has a direction length of about 300 μm and a film thickness of 10 to 20 μm.

Thus, since the magnetoresistive sensor constituting the magnetoresistive head is approximately 1 μm, a sufficiently large output can be obtained, the inductive head is protected, and the influence of stress on the magnetoresistive head is reduced. Can be smaller.

Further, the present invention relates to a magnetic disk drive comprising a disk-shaped recording medium and a composite thin-film magnetic head for recording and reproducing magnetic signals facing the recording surface of the recording medium. It becomes the reproducing head of the head,
A magnetoresistive sensor having a length perpendicular to the surface facing the recording medium and having a length of 0.5 to 1 μm and a recording head of a composite thin-film magnetic head having a thickness of 9 to 1 μm.
An inductive head having a thickness of 2 μm, a length protecting the inductive head in a direction perpendicular to a surface facing the recording medium, of 200 to 300 μm, and a thickness of 1 μm;
And a protective film having a thickness of 0 to 20 μm.

Further, in the above, it is desirable that the protective film is made of alumina.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In recent years, as the recording density of magnetic disk devices has increased, thin-film magnetic heads have been used as magnetic heads for recording and reproducing magnetic recording on and from recording media. Magnetoresistive head using an element exhibiting a magnetoresistive (MR) effect (including a giant magnetoresistive (GMR) effect) in which the resistance changes when an electric current is caused to flow by an external magnetic field and the reproduction is performed by the inductive head described above. The use of a composite type magnetic head performed in the above has been increasing.

In the composite type magnetic head, a magnetic signal written on a recording medium is read by utilizing the magnetoresistance effect. When this reading is performed, a reproduced waveform may be distorted or may be called Barkhausen noise. Noise may occur, causing a reproduction error. As one of the causes, an element exhibiting the MR effect (MR
Influence of stress on the thin film). This is the magnetostriction constant
when l is the film of non-zero (l ≠ 0), generated magnetic anisotropy energy K _u is stress-inducing the stress is present, affects the direction of magnetization of the MR thin film, magnetic characteristics change, its As a result, it is considered that waveform distortion and noise are generated.
Stress-induced magnetic anisotropy energy K _u in the case of uniaxial stress sigma, expressed as _{K u = 3 / 2λσ (1} ). In the case of a general triaxial stress state, the difference (σ ₁ −σ ₂ ) of the main stress in the film surface affects, and the main stress difference is zero (σ ₁ −σ ₂ = 0).
In the case of, _Ku = 0. However, as a result of experiments and finite element method analysis using a three-dimensional model simulating a composite magnetic head, it was found that a main stress difference occurred in the MR thin film.
This is one of the causes of waveform distortion and noise generation.

The mechanism of the main stress difference generation is as follows. The composite magnetic head is composed of a large number of thin films, and is provided with a protective film for the purpose of protecting the films constituting the head. This protective film is usually
It is thicker than other films, but has compressive intrinsic stress. Due to the intrinsic stress of the compression, a bending force is applied to the entire head, and a compression force is applied to the MR film in the film thickness direction. As a result, the MR film tends to expand in the direction perpendicular to the film thickness direction, but since the surface facing the recording medium is a free surface, it expands relatively freely in the direction perpendicular to this surface. However, since there is an electrode or the like in a direction parallel to this plane, the deformation of the MR film is restricted, and a compressive force acts. Therefore, there is a difference between the stress in the direction perpendicular to the surface facing the recording medium and the stress in the direction parallel to this surface, which is the main stress difference.

The main stress difference generated in the MR thin film due to the intrinsic stress of the protective film can be calculated as follows. Fig. 2
Consider a beam having a thickness h, a width b, and a length of 2l, and consider the transmission of force by bending the beam. Here, 2l is the length of the protective film in a direction perpendicular to the surface facing the recording medium. Considering the bending when this beam is separated from the head and held as a single unit, if the displacement in the length direction of the lower surface of the beam is restrained, the beam having the intrinsic stress σ of compression has a stress distribution as shown in FIG. And bending occurs with a maximum deflection d as shown in FIG. Moment M required to produce this bending from the official strength of ^{materials, M = (bh 2/6} ) | a (2) | σ. The maximum deflection d due to the moment M is obtained from the following two equations. M = EI / ρ (3) where E is Young's modulus, I is the second moment of area (= b
h ^3/12), r is the radius of curvature. δ = l ² / 2ρ (4) Actually, since this bending is constrained in the entire head, a load F in the thickness direction is applied to the MR thin film. F is
This is equivalent to the concentrated load F required to return the deflection d to 0 (the direction is reversed). This is equal to the concentrated load F on the free end that causes the maximum deflection d in a beam fixed at one end as shown in FIG. F is obtained as follows. F = (2EI / l ³ ) δ (5) Assuming that F is applied to the MR thin film, the stress σ _{3 in the} thickness direction generated in the MR thin film can be calculated. Let the width (track width) of the MR thin film be b and the length (or MR height) be H
When _MR, a _{σ 3 = F / bH MR (} 6). Assuming that the stress σ ₁ applied in the direction perpendicular to the surface (free surface) facing the recording medium by the action of σ ₃ is 0, the stress σ ₂ in the direction perpendicular to σ ₁ , σ ₃ is σ ₂ = νσ ₃ (7) Here, ν is Poisson's ratio. here,
σ ₂ and σ ₃ are both compressive stresses and take negative values. (2)
From Equations (7), the main stress difference generated in the MR thin film can be obtained as in the following equation. σ ₁ −σ ₂ = (h ² / 4lH _MR ) ν | σ | (8) The intrinsic stress of the compression of the protective film was measured, and σ = about 80MP.
was a. Therefore, in order to evaluate the safe side by estimating the principal stress difference obtained from the equation (8), σ is estimated slightly larger and set to σ = 100 MPa. Generally, alumina is used as the material of the protective film. However, if the material is alumina, it is preferable that the size does not increase any more.

If the dimensions of the head are 2l = 300 mm, H _MR = 1 mm, and the thickness h of the protective film is h = 50 mm, standard recording / reproducing characteristics can be obtained. In this case, if the protective film is made of alumina, the Poisson's ratio ν of alumina is ν = 0.25.
When the principal stress difference is calculated from the equation, σ ₁ −σ ₂ = 104 Mpa.

FIG. 11 shows that σ ₁ −σ ₂ = 245, 135, 0
Output dV and external magnetic field H
Is a result of measuring dV-H characteristics. σ ₁ −σ ₂ = 24
Hysteresis as shown in the figure appears in the dV-H characteristic at 5, 135 MPa. This hysteresis causes waveform distortion, noise, and the like that lead to a reproduction error of the magnetic recording signal. Therefore, in the above-described head in which the main stress difference of σ ₁ −σ ₂ = 104 MPa close to 135 MPa exists, there is a possibility that waveform distortion, noise, and the like may occur.

In order to make the influence of the main stress difference on the magnetic properties negligible, the main stress difference needs to be a small value of about σ ₁ −σ ₂ <10 MPa, and (h ² / 4lH _MR ) ν It is preferable to set the thickness h of the protective film so as to satisfy | σ | <10 (9).

FIG. 5 shows a magnetic disk drive, in which a servo 1 is applied to a recording medium 17 rotated by a spindle motor 16.
3, head support spring 15 driven by actuator 14
The thin-film magnetic head 23 mounted on the leading end of the recording medium 17 so as to face the recording medium 17 records and reproduces a magnetic signal while traveling on the disk surface of the recording medium 17.

Among the thin film magnetic heads, a thin film magnetic head using a magnetoresistive effect head for performing reproduction using a magnetoresistive effect and a recording using an inductive head for performing recording utilizing electromagnetic induction of a coil are used. It is called a head (or a composite magnetic head).

FIG. 6 shows the appearance of the thin-film magnetic head 23. In the thin-film magnetic head 23, a large number of thin films are laminated on the substrate 18 by sputtering or the like. The surface on which the magnetoresistive sensor 19 appears faces the recording medium 17 for recording and reproducing magnetic signals, and is hereinafter referred to as a floating surface. One surface on the substrate perpendicular to the air bearing surface (hereinafter referred to as the head element pattern surface)
An inductive head is formed by laminating a number of thin films including a magnetoresistive sensor 19 on the magnetoresistive effect head, and further laminating a number of thin films including an upper magnetic film 9 on the magnetoresistive effect head. Are stacked, and the protective film 11 is stacked on the inductive head.

FIG. 7 shows the appearance of the head element pattern surface.
FIG. 8 shows the appearance near the sensor portion of the air bearing surface, and FIG. 9 shows an enlarged view near the sensor portion. In FIG. 7, the line segment A-
FIG. 1 is an enlarged view of a cross section of FIG. On the surface of the ceramic substrate 18 on which the head element pattern is formed, an alumina base material 1 is formed with a thickness of about 10 mm, and a lower shield 2 of a Ni-based alloy is formed with a thickness of 1 to 2 mm, and an alumina insulating film 3 is formed with a thickness of about 0.
5mm, Ni-based alloy upper shield 4 is 2-3mm, alumina gap film 5 is about 0.5mm, coil insulating film of resist material
6, 7, 8 are each 3-4 mm, Cu coil conductor 12 is about 3 mm,
The upper magnetic film 9 of FeNi is laminated with 3 to 4 mm or the like.
A magnetoresistive sensor 19 for reproduction made of a thin film of several nm to several tens nm such as NiFe is provided between the lower shield 2 and the upper shield 4. The part sandwiched between the upper shield 4 and the upper magnetic film 9, including the upper shield 4 and the upper magnetic film 9, is the inductive head for recording, and the lower shield 2 and the upper shield 4 including the lower shield 2 and the upper shield 4. The portion sandwiched is the reproducing magnetoresistive head. An alumina protective film 11 is formed on the outermost layer so as to satisfy the above-mentioned expression (9).

When the dimensions of the head are 2l = 300 mm, H _MR = 1 mm, and the protective film is alumina, it is understood from (9) that the thickness h of the protective film should be 15 mm or less. In consideration of protection of the head, the length of the magnetoresistive sensor in the direction perpendicular to the surface facing the recording medium is 0.5 to 1 μm, and the length in the direction perpendicular to the surface facing the recording medium. The thickness is preferably 200 to 300 μm, and the thickness of the protective film is preferably 10 to 20 μm.

Further, for example, 2l = 200 mm or less, _HMR =
If the size is reduced to 0.5 mm, the thickness of the protective film is preferably set to about 9 mm and 8 to 10 mm according to the equation (9).

In the case where the film surface of the protective film is not flat and the film thickness is not uniform, if the thickness h of the protective film is defined where the thickness of the protective film is the largest as shown in FIG. good.

[0026]

According to the present invention, the length of the magnetoresistive sensor is 0.5 to 1 μm, and the length of the protective film is 200 to 3 μm.
Since the thickness is set to 00 μm and the film thickness is set to 10 to 20 μm, the head can be sufficiently protected, the influence on the magnetic properties of the magnetoresistive head can be reduced, and the occurrence of reproduction errors and noise of magnetic recording signals can be reduced. Reliability can be improved.

According to the present invention, the length of the magnetoresistive sensor is about 1 μm, and the length of the protective film is about 300 μm.
m, the film thickness is 10 to 20 μm, so that a sufficiently large output can be obtained, the inductive head can be protected, and the influence of stress on the magnetoresistive head can be reduced.

Further, according to the present invention, the length of the magnetoresistive sensor serving as the reproducing head of the composite thin-film magnetic head is set to 0.5 to 1 μm, and the thickness of the recording head is set to 9 to 12 μm.
μm, the length of the protective film is 200 to 300 μm, and the film thickness is 10 to 20 μm. Therefore, a magnetic disk device with reduced occurrence of errors in reproducing magnetic recording signals and noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a composite thin-film magnetic head according to an embodiment of the present invention.

FIG. 2 is a diagram showing bending of a beam having a thickness h, a width b, and a length 2l.

FIG. 3 is a diagram showing a stress state when bending at a moment M;

FIG. 4 is a diagram showing a state in which a beam fixed at one end is bent by a concentrated load F on a free end.

FIG. 5 is a structural view of a magnetic disk drive according to an embodiment of the present invention.

FIG. 6 is a perspective view showing a composite thin-film magnetic head according to one embodiment of the present invention.

FIG. 7 is a side view showing a head element pattern surface according to one embodiment of the present invention.

FIG. 8 is a front view showing a sensor portion on the air bearing surface according to the embodiment of the present invention.

FIG. 9 is a partially enlarged view of a sensor part in FIG. 8;

FIG. 10 is a sectional view of a composite thin-film magnetic head according to another embodiment of the present invention.

FIG. 11 is a graph showing an external magnetic field and output characteristics for each main stress difference.

[Explanation of symbols]

1… Base material, 2… Lower shield, 3… Insulation film, 4… Upper shield, 5… Gap film, 6, 7, 8… Coil insulation film, 9…
Upper magnetic film, 10: peeling prevention film, 11: protective film, 12: coil conductor, 13: servo, 14: actuator, 15: head support spring, 16: spindle motor, 17: recording medium, 18 ...
Substrate, 19 ... Magnetoresistance effect sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshitaka Ezawa 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. Inside the Machinery Research Laboratory (72) Inventor Ritsu Imanaka 2880 Kozu, Kofu, Odawara City, Kanagawa Prefecture Inside Storage Systems Division, Hitachi, Ltd. (72) Hiroaki Koyanagi 2880 Kozu, Kozu, Odawara City, Kanagawa Prefecture Storage System Business, Hitachi, Ltd. In-house (72) Inventor Yuki Nakamura 2880 Kozu, Odawara-shi, Kanagawa F-term (reference), Hitachi, Ltd. Storage Systems Division 5D033 AA02 BA62 BB43 5D034 BA03 BB09 BB12 BB20 CA04

Claims (5)

[Claims] A magnetoresistive head provided with a base material and a magnetoresistive sensor; an inductive head formed by laminating a thin film on the magnetoresistive head; and protection for protecting the inductive head. A composite thin film magnetic head having a film, wherein the magnetoresistive sensor has a length of 0.5 to 1 μm in a direction perpendicular to a surface facing the recording medium; A thin film magnetic head comprising: the protective film having a length in a direction perpendicular to the vertical direction and a thickness of 200 to 300 μm and a thickness of 10 to 20 μm. 2. A composite thin-film magnetic head according to claim 1, wherein said protective film is made of alumina. 3. A composite thin-film magnetic head comprising: a magnetoresistive head provided with a base material and a magnetoresistive sensor; and an inductive head formed by laminating a thin film on top of the magnetoresistive head. In the above, the magnetoresistive sensor whose length in a direction perpendicular to the surface facing the recording medium is approximately 1 μm, and a direction perpendicular to the surface facing the recording medium that protects the inductive head. Wherein the protective film has a length of about 300 μm and a thickness of 10 to 20 μm. 4. A magnetic disk drive comprising: a disk-shaped recording medium; and a composite thin-film magnetic head for recording and reproducing a magnetic signal facing a recording surface of the recording medium. A magnetoresistive sensor having a length that is 0.5 to 1 μm in a direction perpendicular to a surface facing the recording medium, and a recording head of the composite thin-film magnetic head; An inductive head having a thickness of 9 to 12 μm, and a length of 200 to 300 μm for protecting the inductive head and being perpendicular to a surface facing the recording medium.
m, and a protective film having a thickness of 10 to 20 μm. 5. A magnetic disk drive according to claim 4, wherein said protective film is made of alumina.