Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-06-27
2002-10-01
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S119050, C360S123090
Reexamination Certificate
active
06459542
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic recording head used as, for example, a floating magnetic head and the like, and particularly to a thin film magnetic head in which an upper core layer can precisely be patterned, and a magnetic path formed by lower and upper core layers can be shortened, and a method of manufacturing the thin film magnetic head.
2. Description of the Related Art
FIG. 9
is a partial sectional view showing the structure of a conventional thin film magnetic head (inductive head), and
FIG. 10
is a partial sectional view of the thin film magnetic head taken along line X—X line in
FIG. 9
, as viewed from direction A.
In
FIGS. 9 and 10
, reference numeral
1
denotes a lower core layer made of a magnetic material such as permalloy or the like, and an insulation layer
3
is formed on the lower core layer
1
.
The insulation layer
3
has a trench
3
a
which is formed in the depth direction from the surface (referred to as “ABS” hereinafter) facing a recording medium to have an inner width dimension equal to a track width Tw.
The trench
3
a
contains a bottom pole layer
4
magnetically connected to the lower core layer
1
, a gap layer
5
, and a top pole layer
7
magnetically connected to an upper core layer
6
, which are formed by plating in turn from the bottom.
As shown in
FIG. 10
, the top pole layer
7
formed on the gap layer
5
is formed with a predetermined length dimension Gd from the ABS in the depth direction (the Y direction shown in the drawings), and a Gd setting insulation layer
8
is formed to extend in the depth direction from a portion of the top of the gap layer
5
which is located at the back of the cop pole layer
7
to a portion of the top of the insulation layer
3
which is located at the back of the trench
3
a
of the insulation layer
3
. The Gd setting insulation layer
8
is made of, for example, a resist material. The length dimension Gd of the top pole layer
7
corresponds to the gap depth which has a great effect on the electric properties of the thin film magnetic head, and is thus set to a predetermined length dimension by forming the Gd setting insulation layer
8
.
As shown in
FIG. 10
, a coil layer
9
is formed in a spiral pattern on the insulation layer
3
with the Gd setting insulation layer
8
provided therebetween. The coil layer
9
is made of a conductive material having low electric resistance, for example, such as Cu or the like.
The coil layer
9
is covered with a coil insulation layer
11
made of an organic material or the like, and the upper core layer
6
is formed by plating a magnetic material such as permalloy or the like to extend from the top pole layer
7
to the coil insulation layer
11
. As shown in
FIG. 9
, the width dimension T
1
of the upper core layer
6
exposed in the ABS is larger than the track width Tw, and the upper core layer
6
is magnetically connected to the top pole layer
7
formed in the trench
3
a
of the insulation layer
3
.
In the write inductive head, when a recording current is supplied to the coil layer
9
, a recording magnetic field is induced in each of the lower core layer
1
and the upper core layer
6
so that magnetic signals are recorded on the recording medium such as a hard disk or the like by a leakage magnetic field between the bottom pole layer
4
and the top pole layer
7
magnetically connected to the lower core layer
1
and the upper core layer
6
, respectively.
In the inductive head shown in
FIG. 9
, the insulation layer
3
is formed on the lower core layer
1
and has the trench
3
a
which is formed with a predetermined length L
1
from the ABS in the depth direction (the Y direction shown in FIG.
9
). The trench
3
a
can be formed by, for example, anistropic etching, to have a width dimension in submicron unit.
In the inductive head shown in
FIG. 9
, the inner width dimension of the trench
3
a
is defined as the track width Tw so that the bottom pole layer
4
and the top pole layer
7
magnetically connected to the lower core layer
1
and the upper core layer
6
, respectively, are formed with the gap layer
5
provided therebetween within the track width Tw. Therefore, a leakage magnetic field produced between the bottom pole layer
4
and the top pole layer
7
can be produced in the narrow track width Tw, thereby making the inductive head adaptable for track narrowing accompanying with increases in recording density in future.
However, in the structure of the thin film magnetic head shown in
FIGS. 9 and 10
, the coil layer
9
is formed on the C;d setting insulation layer B formed on the insulation layer
3
, and thus the height dimension H
1
from the top of the top pole layer
7
to the top of the coil insulation layer
11
, which covers the coil layer
9
, is very large.
With a large height dimension H
1
, there is a problem in that the upper core layer
6
cannot be precisely patterned to extend from the top pole layer
7
to the coil insulation layer
11
.
The upper core layer
6
is formed by a so-called frame plating process which comprises coating a resist layer in a region ranging from the top pole layer
7
to the coil insulation layer
11
shown in
FIG. 10
, and then patterning the resist layer in the shape of the upper core layer
6
by exposure and development.
However, with the large height H
1
from the top of the top pole layer
7
to the top of the top of the coil insulation layer
11
, the resist layer formed on the top pole layer
7
has a large thickness, thereby increasing the focal depth in exposure and development. Therefore, the wavelength of an exposure light source is shortened to increase the focal depth. In this case, resolution (resolving power) deteriorates, and particularly, the tip portion
6
a
of the upper core layer
6
cannot be formed in a predetermined shape on the top pole layer
7
.
Furthermore, since the thickness of the resist layer formed on the top pole layer
7
greatly differs from the thickness of the resist layer formed on the coil insulation layer
11
, irregular reflection occurs due to a difference in focus in exposure and development, and thus the upper core layer
6
cannot be precisely patterned in the resist layer.
In the thin film magnetic head shown in
FIG. 10
, the Gd setting insulation layer
8
formed below the coil layer
9
is formed by spin-coating a resist material or the like on the insulation layer
3
.
However, since the Gd setting insulation layer
8
is formed by spin coating, waviness occurs on the surface, and thus formation of the coil layer
9
on such a waviness surface causes a problem in that the coil layer
9
cannot be patterned in an appropriate shape due to a focal disturbance in exposure and development of the resist layer used for forming the coil layer
9
.
Therefore, the pitch T
2
of the coil layer
9
is increased to permit appropriate patterning of the coil layer
9
to some extent. However, in this case, an increase in the pitch T
2
of the coil layer
9
enlarges the entire size of the coil layer
9
, and thus the length dimension from the chip portion
6
a
to the base end
6
b
of the upper core layer
6
must be increased to lengthen the magnetic path formed by the upper core layer
6
and the lower core layer
1
, thereby causing the problem of increasing inductance.
Also, when the height dimension H
1
from the top of the top pole layer
7
to the top of the coil insulation layer
11
is increased, the upper core layer
6
must be formed with a long length. Therefore, in the thin film magnetic head shown in
FIG. 10
, the magnetic path is further lengthened to readily increase inductance.
SUMMARY OF THE INVENTION
The present invention has been achieved for solving the above conventional problems, and an object of the present invention is to provide a thin film magnetic head in which an upper core layer can be precisely patterned, and the length of a magnetic path can be shortened to prevent an increase in inductance, and a method of manufacturing the thin fil
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Evans Jefferson
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