Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-03-28
2002-06-18
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S317000
Reexamination Certificate
active
06407885
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin film magnetic head for writing and reading information at a high density in and out of a hard disk drive (HDD) or the like magnetic recording medium. It also contains method for fabricating the thin film magnetic head.
BACKGROUND OF THE INVENTION
In order to meet the growing needs for increasing the recording capacity in a hard disk drive and the like magnetic recording medium, intensive efforts are being made to increase the recording density.
A conventional thin film magnetic head is described in the following with reference to drawings.
A thin film magnetic head as shown in
FIG. 46
, or a so-called MR inductive complex head, is one of the popular writing/reading heads used in the HDDs. A first combined structure
4605
, which is constituted with a magneto-resistive (MR) film, or a giant magneto-resistive (GMR) film
4602
, formed on a lower shield section
4601
, a hard film
4603
formed at both sides of the film
4602
, and an electrode
4604
formed above the hard film
4603
in the form of a film stretching towards rear portion, is reading section for reproducing signals stored in a magnetic recording medium. A second combined structure
4612
, which is constituted with lower magnetic pole formed of a shared shield section
4606
and a lower write chip section
4607
, a coil
4608
formed above with an insulation layer (not shown) interposed, and upper magnetic pole formed of an upper write chip
4609
and a yoke
4610
, the lower write chip
4607
and the upper write chip
4609
being disposed opposing to each other, is writing section for writing signals in a magnetic recording medium. The “common” shield
4606
is so named because it is part of the lower magnetic pole of the writing section, at the same time it functions as shield for the reading section.
The second combined structure
4612
, or the writing section, is described next referring to FIG.
47
. On the shared shield section
4701
, the lower write chip section
4702
, a gap section
4703
, an upper write chip section
4704
, a first layer coil
4705
, a second layer coil
4706
, and a yoke section
4707
are stacked in the order by a sputtering or the like thin film forming process. The lower write chip section
4702
and the upper write chip section
4704
are generally formed with a magnetic material having a high saturation magnetic flux density (Bs), while the yoke section
4707
is generally formed with a magnetic material having a high resistivity (&rgr;). The gap section
4703
is formed with SiO
2
or the like insulating material, the coils
4705
,
4706
are formed with a copper or the like conductive material. A space formed by the opposing shared shield section
4701
and yoke section
4707
, in which the coils
4705
and
4706
are disposed, is filled with an insulating material
4708
. The coils
4705
,
4706
are winding around the yoke section
4707
in the rear portion where it makes contact with the shared shield section
4701
. The coils
4705
,
4706
generate magnetic fields, when provided with electricity, in the outside of the gap section
4703
to write signals in a magnetic recording medium. Hereunder, the writing section will be referred to as thin film magnetic head.
In the conventional thin film magnetic head, where the upper write chip section and the yoke section, these constitute the upper magnetic pole, are making contact only in a region of the head track width and the head gap depth, the upper write chip section is not supplied with sufficient magnetic flux from the yoke section. Even if the saturation magnetic flux density (Bs) is enhanced with the upper write chip section and the lower write chip section it is difficult for the writing magnetic fields to go stronger because of influence by the magnetic saturation. Problem is that the writing magnetic fields are not strong enough for recording signals in a high coercive force (Hc) recording medium, which has been making a significant advance for high density recording. While on the other hand, if the head track width is made smaller for the higher recording density, the contact region between the upper write chip section and the yoke section goes smaller, and the recording magnetic fields eventually go even weaker. Thus the effectiveness on the high Hc recording medium is retarded.
SUMMARY OF THE INVENTION
A thin film magnetic head of the present invention comprises a lower magnetic pole including a shared shield section and a lower write chip section made of a high Bs magnetic layer disposed on the upper surface of the shared shield section at the tip end portion; a gap section formed on the upper surface of the lower write chip section; an upper magnetic pole including an upper write chip section made of a high Bs magnetic layer disposed on the gap section, opposing to the lower write chip section, and a yoke section made of a high &rgr; magnetic layer that makes contact in a part with the lower magnetic pole while coupled at the tip end portion with the upper write chip section; and a coil winding around going through a space formed by the opposing magnetic poles, in a region between the both magnetic poles' contact area and the upper write chip section, and a space behind the yoke section. Wherein, the upper write chip section is longer than the lower write chip section in the direction of the depth.
Under the above-described configuration, where the upper write chip section is longer than the lower write chip section, area of contact between the upper write chip section and the yoke section can be increased. Therefore, strong recording magnetic fields are made available with sufficient supply of magnetic flux from the yoke section. Furthermore, the yoke section of the upper magnetic pole made of a high &rgr; magnetic layer provides favorable high frequency characteristics.
A preferred example of the thin film magnetic head in accordance with the present invention is that the width of yoke is made greater in a region coupling with the upper write chip section than the head track width formed by the upper write chip section and the lower write chip section. The greater width of the yoke section, which is formed of the high &rgr; magnetic layer, eases the magnetic saturation at the tip end of yoke, and a plenty amount of magnetic flux is supplied to the tip end of the yoke section. Thus, strong recording magnetic fields are made available through the upper write chip section to an improved recording efficiency.
Other exemplary thin film magnetic head of the present invention is that the end surface at the tip end of the yoke section coupled to the upper write chip section is locating inward relative to the end face of the upper write chip section. This configuration suppresses the fringe at the head gap section, and enables to reduce the track pitch for an increased surface recording density.
Still other example of thin film magnetic head is that it is provided with a shared shield section that has a hollow in an area corresponding to the coil. This configuration reduces inductance of a magnetic pole formed by the upper magnetic pole and the lower magnetic pole, and the high frequency characteristics may be improved.
A method for fabricating a thin film magnetic head of the present invention comprises a first step for forming an insulating layer on the flat upper surface of a shared shield section; a second step of dry-etching the insulating layer for exposing the upper surface of the shared shield section so that an edge line of the insulating layer after the dry-etching assumes a straight line shape; a third step for forming a lower high Bs magnetic layer on the exposed upper surface of the shared shield section and the upper surface of the insulating layer; a fourth step of polishing the upper surface of the insulating layer and the upper surface of the lower high Bs magnetic layer to be in parallel with the upper surface of the shared shield section; a fifth step for forming a gap layer on the upper surfaces of the lower high Bs magnetic layer and
Ahagon Akira
Mitani Satoru
Sakaguchi Masaya
Tsuji Hiroyasu
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
Tupper Robert S.
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