Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2000-03-10
2001-08-21
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
Composite
Of inorganic material
C360S125330
Reexamination Certificate
active
06277506
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thin film magnetic head, a substrate for the thin film magnetic head, and a method for fabricating the substrate for the thin film magnetic head.
In recent years, thin film magnetic heads are used for various magnetic recording devices such as hard disk drive (HDD) devices and floppy disk drive (FDD) devices. Such a thin film magnetic head is essentially composed of a substrate, a magnetic shield film deposited on the substrate, and a magnetic element (such as a magnetoresistance (MR) element) and a recording head section formed on the magnetic shield film. The magnetic shield film is made of a soft magnetic material such as Fe—Ni permalloy, Co—Nb—Zr and Co—Fe—B—Si Co-base amorphous materials, and FeAlSi alloy (sendust). As the substrate of the thin film magnetic head, broadly used is a type having an insulating layer made of aluminum oxide deposited on a ceramic base plate made of alumina titanium carbide (AlTiC).
The above thin film magnetic head has a drawback as follows. The adhesion between the AlTiC base plate and the aluminum oxide layer formed thereon is poor, whereby the aluminum oxide layer tends to delaminate from the AlTiC base plate at the interface during the fabrication process and mounting process of the thin film magnetic head, as well as during the actual use thereof. Methods for solving this problem have been proposed, including the method in which an interlayer is provided between the AlTiC base plate and the aluminum oxide layer (see Japanese Patent Publication No. 2-59604) and the method in which the surface of the AlTiC base plate is roughened (see Japanese Laid-Open Patent Publication No. 2-154308). However, there has yet been realized neither a thin film magnetic head substrate of which the AlTiC base plate and the aluminum oxide layer adhere to each other with sufficiently high strength, nor an efficient method for fabricating such a substrate.
A primary object of the present invention is to provide a thin film magnetic head substrate with high reliability where the AlTiC base plate and the aluminum oxide layer adhere to each other with high adhesion strength, and an efficient method for fabricating such a thin film magnetic head substrate.
SUMMARY OF THE INVENTION
The thin film magnetic head substrate of the present invention includes an alumina titanium carbide base plate and an aluminum oxide layer formed on the alumina titanium carbide base plate, wherein the alumina titanium carbide base plate has a surface modified layer in a surface portion facing the aluminum oxide layer, and the surface modified layer includes aluminum titanate.
Preferably, portions of alumina particles included in the alumina titanium carbide base plate that constitute part of the surface modified layer include &agr;-Al
2
O
3
, Al
2
TiO
5
, and Al
2
Ti
7
O
15
.
Also preferably, portions of titanium carbide particles included in the alumina titanium carbide base plate that constitute part of the surface modified layer include cubic TiC, Al
2
TiO
5
, and Al
2
Ti
7
O
15
.
Still preferably, the centerline average surface roughness Ra of the surface modified layer is less than about 10 nm.
Still preferably, the thickness of the surface modified layer is in the range between about 5 nm or more and about 500 nm or less.
The thin film magnetic head of the present invention includes: the thin film magnetic head substrate described above; and a magnetic element formed on the thin film magnetic head substrate.
According to another aspect of the invention, a method for fabricating a thin film magnetic head substrate is provided. The thin film magnetic head substrate includes an alumina titanium carbide base plate and an aluminum oxide layer formed on the alumina titanium carbide base plate. The method includes the steps of: preparing the alumina titanium carbide base plate; modifying a surface of the alumina titanium carbide base plate into a layer including aluminum titanate by inverse sputtering in an atmosphere containing at least an inert gas; and depositing the aluminum oxide layer on the layer including aluminum titanate after the surface modifying step.
Preferably, the surface modifying step includes the step of modifying a surface of the alumina titanium carbide base plate into a layer including aluminum titanate while etching the surface of the alumina titanium carbide base plate.
Also preferably, the thickness of the layer including aluminum titanate formed in the surface modifying step is in the range between about 5 nm or more and about 500 nm or less.
Still preferably, the thickness of the surface of the alumina titanium carbide base plate etched in the surface modifying step is less than about 10 nm.
Still preferably, the atmosphere in the surface modifying step is an atmosphere containing argon gas and oxygen gas having a pressure in the range of about 2 mTorr to about 20 mTorr, and the proportion of the oxygen gas in the atmosphere is about 40% or less.
Still preferably, the method further includes the step of: grinding the alumina titanium carbide base plate so that the centerline average surface roughness Ra is about 10 nm or less.
REFERENCES:
patent: 5764454 (1998-06-01), hishida
patent: 5901021 (1999-05-01), hirano et al.
patent: 5914285 (1999-06-01), sasaki et al.
patent: 60-39807 (1985-03-01), None
patent: 60-229233 (1985-11-01), None
patent: 2-154308 (1990-06-01), None
Costellia Jeffrey L.
Lam Cathy
Nixon & Peabody LLP
Sumitomo Special Metals Co. Ltd.
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