Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
1998-07-17
2001-07-17
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Forming or treating article containing magnetically...
C216S066000, C216S067000, C204S192340, C029S603150
Reexamination Certificate
active
06261468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to combination read/write thin film magnetic heads used in floating-type magnetic heads and the like. In particular, the present invention relates to a combination read/write thin film magnetic head and a method for making the same, in which the track width of a magnetic gap of an inductive thin film magnetic head is highly precisely formed in order to reduce occurrence of write fringing.
2. Description of the Related Art
FIG. 14
is a longitudinal sectional-view of a conventional combination read/write thin film magnetic head, and
FIG. 15
is a section facing a recording medium of the magnetic head shown in
FIG. 14 and a
fragmentary front view along arrow XV in FIG.
14
. The magnetic head shown in
FIGS. 14 and 15
is an inductive magnetic head which writes signals on a recording medium such as a hard disk. The inductive magnetic head is superposed with a reading head which uses the magnetoresistance effect at the trailing edge of the slider of a floating-type magnetic head which faces a recording medium such as a hard disk.
Identification number
11
in
FIG. 14
represents a lower-core layer composed of a high magnetic permeability material such as a Fe-Ni alloy (permalloy). In a combination read/write thin film magnetic head in which an inductive head shown in
FIG. 14
is continuously superposed with a reading head which uses the magnetoresistance effect, the lower-core layer
11
acts as an upper-shielding layer of the reading head.
A gap layer
12
composed of a nonmagnetic material such as Al
2
O
3
(aluminum oxide) is provided on the lower-core layer
11
. An insulating layer
4
composed of an organic material, such as a resist material, is formed on the gap layer
12
.
A coil layer
5
composed of an electrically conductive material having a low electric resistance, such as Cu, is spirally formed on the insulating layer
4
. Herein, the coil layer
5
is formed so as to surround the periphery of the base end
7
b
of the upper-core layer
7
, and a part of the coil layer
5
is shown in FIG.
14
.
An insulating layer
6
composed of an organic resinous material is formed on the coil layer
5
. An upper-core layer
7
composed of a magnetic material such as permalloy is formed by plating on the insulating layer
6
. The front end
7
a
, facing the recording medium, of the upper-core layer
7
is jointed to the lower-core layer
11
through the gap layer
12
. The base end
7
b
of the upper-core layer
7
is magnetically connected to the lower-core layer
11
through the holes formed in the gap layer
12
and the insulating layer
4
.
In the inductive writing head, a recording current circulating in the coil layer
5
induces a recording magnetic field in the lower-core layer
11
and the upper-core layer
7
, and magnetic signals are recorded on a recording medium such as a hard disk by means of a leakage magnetic field from the magnetic gap between the lower-core layer
11
and the front end
7
a
of the upper-core layer
7
.
In the magnetic gap for the inductive writing head, the gap length G
1
is determined by the distance between the lower-core layer
11
and the front end
7
a
of the upper-core layer
7
which are jointed through the gap layer
12
, i.e., the thickness of the gap layer
12
, and the gap depth Gd is determined by the depth at the front end
7
a
of the upper-core layer
7
. Further, the track width Tw is determined by a width of the front end
7
a
of the upper-core layer
7
, as shown in FIG.
15
.
As shown in
FIG. 15
, the width T
3
of the lower-core layer
11
is sufficiently larger than the width of the front end
7
a
of the upper-core layer
7
, because the lower-core layer
11
has magnetic shield effects to a magnetoresistive element
13
which is formed below the inductive head. That is, in a reading head which uses the magnetoresistance effect as shown in
FIG. 15
, the magnetoresistive element
13
is provided on a lower-shielding layer
14
through the lower-gap layer
15
a
and the lower-core layer
11
is formed on the magnetoresistive element
13
through the upper-gap layer. The lower-core layer
11
also acts as the upper-shielding layer to the magnetoresistive element
13
. The width T
3
of the lower-core layer
11
therefore is sufficiently larger than the width of the magnetoresistive element
13
in order to achieve the function as the upper-shielding layer.
As shown in
FIG. 15
, a width T
3
of the lower-core layer
11
larger than the width Tw of the front end
7
a
of the upper-core layer
7
induces a recording magnetic field in the lower-core layer
11
and the upper-core layer
7
, and a leakage magnetic field formed between the front end
7
a
and the lower-core layer
11
leaks out of the track width Tw. A leakage magnetic field is also formed beside both sides of the track width Tw due to a large width of the lower-core layer
11
.
As a result, the magnetic signals formed on the recording surface of a recording medium such as a hard disk has write fringing or writing blot of magnetic signals which is formed out of the given width Tw of the recording track. The write fringing inhibits high precision detection of the track position in the written recording medium and results in tracking servo errors. In particular, the write fringing significantly affects high density recording with a narrow track pitch.
FIG. 16A
is a front view from the recording medium side of an improved head which can suppress the write fringing. In
FIG. 16A
, after a gap layer
12
is formed on the lower-core layer
11
and a front end
7
a
of an upper-core layer
7
is formed on the gap layer
12
, the lower-core layer
11
and the gap layer
12
are removed by ion milling or the like to form grades
11
a
and
12
a
over the lower-core layer
11
and the gap layer
12
at both edges of the front end
7
a
of the upper-core layer
7
. Both of the grades
11
a
and
12
a
have an angle &thgr;
5
.
Because the grades
12
a
are simultaneously formed over both ends of the gap layer
12
by the ion-milling process for forming the lower-core layer
11
and the gap layer
12
, the width T
6
of the face
11
b
of the lower-core layer
11
facing the front end
7
a
is larger than the width Tw of the front end
7
a
.
FIG. 16B
represents a recording pattern of magnetic data recorded with this head. Since the width T
6
of the face
11
b
is larger than the width Tw, the writing magnetic field leaks out of the track width Tw at the right and left ends to form write fringing.
The head shown in
FIG. 16A
can reduce write fringing compared to that shown in
FIG. 15. A
finer track pitch for high density recording will cause some detecting errors due to the write fringing shown in
FIG. 16B
, and thus the improvement shown in the drawing will be insufficient.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a combination read/write thin film magnetic head which improves or significantly reduces write fringing, has a simple head configuration, and is capable of ready production.
It is another object of the present invention to provide a method for making the above-mentioned combination read/write thin film magnetic head.
A combination read/write thin film magnetic head in accordance with the present invention comprises:
a lower-shielding layer comprising a magnetic material, a nonmagnetic lower-gap layer, a magnetoresistive element and a nonmagnetic upper-gap layer, these layers being superposed in this order from the bottom; and
a lower-core layer comprising a magnetic material, an upper-core layer comprising a magnetic material facing the lower-core layer through a nonmagnetic gap layer, and a coil layer inducing a recording magnetic field in the lower-core layer and upper-core layer, these layers being provided on the upper-gap layer and the lower-core layer also acting as an upper-shielding layer;
wherein the width of the gap layer is the same as the width Tw of the upper-core layer; the lower-core layer is provided with a promin
Ishibashi Naohiro
Sato Kiyoshi
Alanko Anita
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Gulakowski Randy
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