JP2001126222A - Substrate for thin film magnetic head and thin film magnetic head utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a heat radiating characteristic of an element part of a thin film magnetic head, to prevent contact of the element with a media surface and to provide a substrate for the thin film magnetic head excellent in film adhesive strength, breakdown strength and surface quality. SOLUTION: A first amorphous alumina film having 10-5,500 Åthickness by an ECR sputtering method and a second amorphous alumina film having 0.2-2.4 μm thickness by a sputtering method are successively laminated on a base to form the substrate for the thin film magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head used for a hard disk drive or a tape drive as a recording device of a computer and a substrate for the thin film magnetic head used for the same.

[0002]

2. Description of the Related Art Conventionally, substrates for thin-film magnetic heads include:
Alumina (Al ₂ O ₃ ) and titanium carbide (Ti
An insulating film made of amorphous alumina is formed on a ceramic substrate made of the composite material C) by a sputtering method, and the surface thereof is mirror-finished by a single-side polish machine. This insulating film is formed to obtain insulation from the ceramic substrate, which is a conductive material, and smoothness of the film formation surface. The surface roughness of the insulating film is particularly important for forming an element thereon. It is. The film formation surface is formed by CMP (CHEMICAL MECHA) so as to be smoother.
NICOL POLISHING), and in recent years this demand has been increasing.

In order to improve the recording density of a hard disk drive, an MR (magnetoresistive) using a magnetoresistive effect in an element of a thin-film magnetic head is used.
VE) or GMR (GIANT MR) is used, and in the case of such an MR element or GMR element, it is necessary to increase the sense current in order to improve the reading sensitivity.

[0004] Further, the MR for a hard disk drive is used.
As shown in FIG. 4, the head and the GMR head are made of Al ₂ O ₃
A slider 3 made of a composite material of TiC and an MR element 4 provided through an amorphous alumina film,
The head flying height 10 is as small as about 1 microinch, and the state is near contact. Therefore, the thin-film magnetic head 2 and the medium 5 are liable to make contact and slide, and the frictional heat at this time causes the temperature of the MR element 4 of the thin-film magnetic head 2 to rise, and as a result, the reading sensitivity is reduced. It is becoming a big problem.

In order to solve such a problem, the MR
It is necessary to increase the heat radiation around the element 4, and for that purpose, a technique has been proposed in which a base film of the MR element 4 is formed of a high thermal conductive material such as AlN. However, when a film is formed from the above-mentioned high thermal conductive insulating material, the film stress becomes extremely high. Therefore, when the film thickness is 2 μm or more, the substrate is deformed and peeling occurs. On the other hand, if the film thickness is less than 2 μm,
The electrical withstand voltage becomes insufficient, and a sufficient polishing allowance cannot be obtained for polishing the film formation surface to obtain smoothness.

Further, the thickness of the amorphous alumina film is reduced, and the MR element 4 is made to have a high thermal conductivity by the slider 3 (A).
(l ₂ O ₃ —TiC substrate) to improve heat dissipation, or prevent the MR element 4 from colliding with the medium 5 by utilizing the recess 11 due to the hardness difference between the thin film magnetic head 2 and the amorphous alumina film. Although some measures have been taken to reduce the thickness of the amorphous alumina film,
m or less, it was insufficient in withstand voltage.

Therefore, the thickness of the amorphous alumina film is reduced to form a first layer, and an amorphous alumina film is formed on this film by ECR sputtering to form a second layer.
The present applicant has proposed that a thin film magnetic head having excellent film adhesion strength and electrical withstand voltage can be obtained by securing a film thickness as a layer (see Japanese Patent Application No. 10-18192).

[0008]

However, when the first layer is formed by a normal sputtering method and the second layer is formed by an ECR sputtering method, the thickness of the second layer cannot be increased. However, there is a problem that a sufficient polishing allowance cannot be secured to control the surface roughness and flatness.

[0009]

In order to solve the above-mentioned problems, a thin film magnetic head substrate according to the present invention comprises a first amorphous alumina film having a thickness of 10 to 5500 ° formed by ECR sputtering on a substrate and a conventional sputtering method. A second amorphous alumina film having a thickness of 0.2 to 2.4 μm formed by a method is sequentially laminated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described specifically.

As shown in FIG. 1 (a), a thin-film magnetic head substrate 1 of the present invention has a disk shape of 3 to 8 inches in diameter having an orientation flat, or 3 sides as shown in FIG. 1 (b). It is a square plate of about 6 inches. As shown in FIG. 2, this thin-film magnetic head substrate 1 is made of Al ₂ O ₃ −
The first and second amorphous alumina films 7 and 8 are formed on a substrate 6 made of TiC-based ceramics.

[0012] Al ₂ O ₃ -TiC based ceramic constituting the substrate 6, and 60-80% of Al ₂ O ₃ with a raw material composed mainly of 40 to 20% of TiC, atmospheric or reduced atmosphere 1600～ Hot press at 1800 ° C or H
The IP treatment results in a very dense sintered body, and the surface can be smoothed by processing. This Al ₂ O ₃ -Ti
The C-based ceramic is a conductive material, but the first,
By forming the second amorphous alumina films 7 and 8, insulation properties are provided.

Here, the method of manufacturing the thin film magnetic head according to the present invention will be specifically described. As shown in FIG. 2, first, Al ₂ O ₃
Forming a first amorphous alumina film 7 on the TiC-based ceramic substrate 6 by ECR sputtering, and then forming a second amorphous alumina film 8 by ordinary sputtering; Further, a multi-magnetic film 9 as shown in FIG. 3 is formed, and thousands of MR elements are formed on the upper surface thereof by lithography. An amorphous alumina film is further formed thereon by a sputtering method. Then, it is cut into a bar shape, one surface of which is precision mirror-finished as a sliding surface, grooved with high precision using an ion milling method or a reactive ion etching (RIE) method, and then cut out, as shown in FIG. Slider 3 (A
l ₂ O ₃ -TiC based ceramic substrate 6) first on the second
The thin film magnetic head 2 provided with the MR element 4 is obtained via the amorphous alumina films 7 and 8 described above.

In the second amorphous alumina film 8 formed by the ordinary sputtering method, defects may be generated in the film. However, the first amorphous alumina film 7 formed by the ECR sputtering method has a film filling rate. Therefore, an insulating film having a high withstand voltage without penetrating defects can be obtained. In addition, since both are made of the same material, the adhesion between them is high.

[0015] Further, by reducing the thickness of the insulating film, FIG.
As shown in (1), since the frictional heat can be more quickly transmitted to the slider 3 having high thermal conductivity, the heat dissipation of the MR element 4 can be improved. Moreover, at this time, the MR element 4 is
, It is difficult for the same recess 11 to come into contact with the medium 5.

Further, the second amorphous alumina film 8
Is formed by an ordinary sputtering method, so that its surface can be subjected to CMP processing by an established technique. As a result, it is possible to provide a surface having a higher surface quality than the surface formed by the ECR sputtering method, and more specifically, to provide the substrate 1 for a thin-film magnetic head having a surface roughness of Ra3Å or less.

The thickness of the first amorphous alumina film 7 formed by the ECR sputtering method is 10 to 5500
{Preferably, 10 to 5000}, the thickness of the second amorphous alumina film 8 formed by a normal sputtering method is 0.2 to 2.4 μm, preferably 0.2 to 2.0 μm.
m. This is because polishing is difficult when the thickness of the amorphous alumina film by a normal sputtering method is less than 0.2 μm, and the insulating property is not obtained. When the thickness is 2.4 μm or more, the heat radiation property deteriorates, Also M
This is because the R element 4 easily contacts the medium 5.
If the thickness of the amorphous alumina film formed by the ECR sputtering method is less than 10 °, insulating properties cannot be obtained, and
If it exceeds 500 °, peeling occurs due to the stress of the film.

Note that the first amorphous alumina film 7 formed by the ECR sputtering method and the second amorphous alumina film 8 formed by the ordinary sputtering method can be observed by observing the cut surface of the substrate after the film formation. If the interface between the two films can be recognized, it is possible to determine whether the amorphous alumina film formed by the ECR sputtering method or the amorphous alumina film formed by the conventional sputtering method from the processing rate when the cut surface is subjected to the CMP processing. it can.

[0019]

Embodiments of the present invention will be described below.

As a starting material, alumina (purity 99.9)
%, Average particle size of raw material powder: 0.4 μm) and titanium carbide (purity: 99.5%, average particle size of raw material powder: 0.3 μm)
m), and weighed so that the ratio of alumina was 70% by weight and titanium carbide was 30% by weight, and about 10% by weight of titanium oxide was added to titanium carbide, and mixed and pulverized with alumina balls. This mixed powder was molded and baked for 1 hour at 1600 ° C. under a pressure of 250 kg / cm ² .

The sintered body thus obtained was ground into a predetermined disk shape by a diamond wheel, and then wrapped by using diamond abrasive grains. Further, using a diamond powder having an average particle diameter of 0.5 μm, the substrate surface and the polishing board or polishing cloth were slid relatively to each other to perform precision polishing, thereby setting the surface roughness Ra of the substrate to 18 °. In this embodiment, a tin surface plate was used as the polishing plate.

Thereafter, an amorphous alumina film was formed on the substrate under various conditions. Sample No. For 1 to 6, an amorphous alumina film was formed by a normal sputtering method using an alumina target having a purity of 99.5%, and then a polishing liquid in which spherical alumina fine powder was suspended in pure water. After mirror finishing, the final precision processing was performed with a polishing liquid in which spherical fine ceria powder was suspended in pure water.
4 μm, and film surface roughness (Ra) 3 °. Sample No.
For 5 and 6, a second amorphous alumina film was further formed by a normal sputtering method, and subjected to the same precision processing.

The sample No. For 7 to 12, EC
After forming a first amorphous alumina film by using the R sputtering method, a second amorphous alumina film is formed by a normal sputtering method, and a polishing liquid in which spherical alumina fine powder is suspended in pure water is used. After the mirror finishing, the final fine processing is further performed using a polishing liquid in which spherical fine ceria powder is suspended in pure water, the film thickness is 1 to 2 μm, and the film surface roughness (Ra)
3Å.

Each of these samples was evaluated for film peeling, surface roughness and resistance after the heat treatment. Here, regarding the film peeling after the heat treatment, each sample was placed in a vacuum atmosphere for 60 hours.
Heat at a temperature of 0 ° C., and observe the state of the film surface with a differential interference microscope (5
0 times). The surface roughness was measured by AFM.
Regarding the resistance value, Ti / Au electrodes were formed at 20 places / φ4 microinch on the film surface, and the applied voltage was 10 V at room temperature.
Was used as the lowest resistance value when the distance between the film surface and the back surface of the substrate was measured using a three-terminal method.

As a result, as shown in Table 1, Samples 1-4
In the case of only the first amorphous alumina film formed by the ordinary sputtering method as described above, a resistance value of 10 ¹¹ Ω or more cannot be obtained unless a film thickness of 4 μm or more is formed.
In the case of when the two-layered film of the second amorphous alumina film was formed by a conventional sputtering method as described above, they tend to be the higher the resistance the same thickness, the resistance value 10 ¹¹ a thickness 3μm or less It became less than Ω. In addition, the sample No. In the case where the second amorphous alumina film was formed to have a thickness of 6000 ° as in the case of 12, the film was peeled off by the heat treatment in vacuum because the stress caused by the density difference between the two layers was too high.

On the other hand, the sample No. In Examples 7 to 11 of the present invention, even when the thickness of the amorphous film was within 2.5 μm, the resistance value was 10 ¹¹ Ω or more, excellent withstand voltage was obtained, and no film peeling occurred after the heat treatment.

[0027]

[Table 1]

[0028]

As described above, in the present invention, the thickness of the substrate formed by ECR sputtering on the substrate is 10 to 5 mm.
By sequentially laminating a first amorphous alumina film of 500 ° and a second amorphous alumina film having a thickness of 0.2 to 2.4 μm formed by a normal sputtering method,
The surface roughness and flatness of the film formation surface of the thin film head substrate can be easily controlled. Further, a thin film magnetic head formed by forming a magnetic film on the substrate can improve the heat radiation of the MR element.

[Brief description of the drawings]

FIGS. 1A and 1B are perspective views showing a substrate for a thin-film magnetic head according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the thin film magnetic head substrate of the present invention.

FIG. 3 is a schematic view showing a film layer structure of the thin-film magnetic head of the present invention.

FIG. 4 is a sectional view showing a state of use of the thin-film magnetic head of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 thin-film magnetic head substrate 2 thin-film magnetic head 3 slider 4 MR element 5 media 6 Al ₂ O ₃ —TiC-based ceramic substrate 7 first amorphous alumina film 8 second amorphous alumina film 9 magnetic film 10 head flying height 11 recess

Claims (2)

[Claims] A first amorphous alumina film having a thickness of 10 to 5500 ° formed by ECR sputtering and a second amorphous alumina film having a thickness of 0.2 to 2.4 μm formed by sputtering are sequentially laminated on a substrate. A substrate for a thin-film magnetic head, comprising: 2. A thin-film magnetic head according to claim 1, wherein a magnetic film is formed on the second amorphous alumina film in the thin-film magnetic head substrate.