Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-11-05
2004-05-18
Ometz, David (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06738222
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a thin-film magnetic head having at least an induction-type electromagnetic transducer for writing, and to a method of manufacturing such a thin-film magnetic head.
The recording schemes for a magnetic read/write apparatus include a longitudinal magnetic recording scheme which employs the direction of signal magnetization along the surface of a recording medium (or in the longitudinal direction) and a vertical magnetic recording scheme which employs the direction of signal magnetization perpendicular to the surface of the recording medium. When compared with the longitudinal magnetic recording scheme, the vertical magnetic recording scheme is said to be less affected by the thermal fluctuation of a recording medium and therefore possible to implement a higher linear recording density.
In general, the thin-film magnetic head that employs the longitudinal magnetic recording scheme comprises: a medium facing surface (or air bearing surface) that faces toward a recording medium; a first magnetic layer and a second magnetic layer magnetically coupled to each other and including magnetic pole portions that are opposed to each other and placed in regions of the magnetic layers on a side of the medium facing surface, with a gap layer provided between the pole portions; and a thin-film coil at least a part of which is placed between the first and second magnetic layers and insulated from the first and second magnetic layers.
On the other hand, examples of the thin-film magnetic head that employs the vertical magnetic recording scheme include a ring head having the same structure as that of the thin-film magnetic head that employs the longitudinal magnetic recording scheme, and a single magnetic pole head for applying a magnetic field in a direction perpendicular to the surface of a recording medium with one main magnetic pole. Generally, for the single magnetic pole head, used as a recording medium is a two-layer medium that has a soft magnetic layer and a magnetic recording layer stacked on a substrate.
With an increase in the recording density in recent years, track widths of thin-film magnetic heads have been required to be reduced. Accordingly, it has also been desired that the main magnetic pole in the aforementioned single magnetic pole head be reduced in width. However, as described below, there have been two problems which make it difficult to reduce the width of the main magnetic pole.
A first problem is that it is difficult to pattern the main magnetic pole with high accuracy, for example, in such a manner that the main magnetic pole is made to have a width of 0.5 &mgr;m or less. The main magnetic pole is formed by electroplating (frame plating), for example, using a resist frame that is formed by photolithography. Conventionally, the main magnetic pole is formed on a hill-like raised portion of an insulating layer that covers the coil, and therefore, the resist frame is formed on the insulating layer having great differences in height of irregularities. In this case, it is difficult to form the resist to have a uniform thickness, and accordingly it is difficult to pattern the resist frame with accuracy. This in turn makes it difficult to pattern the main magnetic pole with high accuracy.
A second problem is that a reduction in width of the main magnetic pole causes a magnetic flux to be saturated before the flux reaches the tip of the main magnetic pole, thereby causing a reduction in the magnetic field generated from the tip of the main magnetic pole in the medium facing surface.
Conventional thin-film magnetic heads for use with the longitudinal magnetic recording scheme have encountered similar problems. To overcome these problems, thin-film magnetic heads for use with the longitudinal magnetic recording scheme often employ a structure in which one of magnetic layers is divided into a magnetic pole portion to be exposed in the medium facing surface and a yoke portion for introducing magnetic flux into the magnetic pole portion.
Accordingly, it has been proposed for the single magnetic pole heads for use with the vertical magnetic recording scheme, too, to employ such a structure in which the main magnetic pole is divided into a magnetic pole portion to be exposed in the medium facing surface and a yoke portion for introducing magnetic flux into the magnetic pole portion. This structure makes it possible to efficiently introduce magnetic flux to the tip of the main magnetic pole and to form a magnetic pole portion that is small in width, by making the saturated magnetic flux density of the magnetic pole portion greater than that of the yoke portion.
Incidentally, for conventional thin-film magnetic heads for use with the longitudinal magnetic recording scheme, where they are configured such that one magnetic layer is divided into a magnetic pole portion and a yoke portion, the yoke portion has often been joined to only one of surfaces of the magnetic pole portion that is farther from the gap portion. However, this structure provides only a small area of the interface between the magnetic pole portion and the yoke portion, which causes a magnetic flux to be readily saturated at the interface. Therefore, this structure cannot meet the recent demand for increasing magnetic fields for writing operations. To overcome this, thin-film magnetic heads having the following structure have been proposed in Published Unexamined Japanese Patent Application (KOKAI) No. Hei 11-102506, No. 2000-57522, No. 2000-67413 and No. 2000-149218. That is, the heads have a structure in which the yoke portion is joined to the magnetic pole portion not only at the surface of the magnetic pole portion farther from the gap portion but also at both side surfaces of the magnetic pole portion and at a surface of the magnetic pole portion farther from the medium facing surface.
For the single magnetic pole heads for use with the vertical magnetic recording scheme, where they are configured such that the main magnetic pole is divided into the magnetic pole portion and the yoke portion, it is conceivable to employ the structure in which the yoke portion is joined to the magnetic pole portion not only at the surface of the magnetic pole portion farther from the gap portion but also at the side surfaces of the magnetic pole portion and the surface of the magnetic pole portion farther from the medium facing surface, like the aforementioned heads for use with the longitudinal magnetic recording scheme.
For a head for use with the vertical magnetic recording scheme, it is important to increase the intensity of magnetic field in the direction perpendicular to the surface of the recording medium. However, even if the aforementioned structure is employed for the head for use with the vertical magnetic recording scheme, it is impossible to increase the intensity of the magnetic field in the direction perpendicular to the recording medium, because the areas of the interfaces between the yoke portion and the magnetic pole portion obtained at the surface of the magnetic pole portion farther from the medium facing surface or at the side surfaces of the magnetic pole portion are relatively small as compared with the area of the interface at the surface of the magnetic pole portion farther from the gap portion.
For the head for use with the vertical magnetic recording scheme, the main magnetic pole is preferably disposed on the leading side in the traveling direction of the recording medium (or on the air-outflow-end side of the slider including the thin-film magnetic head) in order to improve the linear recording density. In this case, to further improve the linear recording density, it is preferable that one of ends of the magnetic pole portion of the main magnetic pole that is farther from the gap portion be flat in the medium facing surface. However, in the head in which the yoke portion layer is disposed to touch the surface of the magnetic pole portion farther from the gap portion, the surface of the pole portion layer farther from the
Roppongi Tetsuya
Sato Yoshikazu
Blouin Mark
Ometz David
TDK Corporation
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