Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-03-08
2004-07-27
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S122000
Reexamination Certificate
active
06768611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to a recording thin film magnetic head used as, for example, a flying magnetic head or the like and, more particularly, to a thin film magnetic head that is capable of appropriately decreasing side fringing, and that can be manufactured with high reproducibility, and a method of manufacturing the same.
2. Description of the Related Art
FIG. 24
is a partial front view showing the structure of a conventional thin film magnetic head (inductive head), and
FIG. 25
is a partial cross-sectional view of the thin film magnetic head shown in FIG.
24
.
In
FIGS. 24 and 25
, reference numeral
1
denotes a lower core layer made of a magnetic material such as permalloy or the like, with insulation layers
3
formed on both sides of the lower core layer
1
. As shown in
FIG. 24
, a gap layer
4
and an upper pole layer
5
are formed with track width Tw on the lower core layer
1
to be exposed in the surface facing a recording medium. The gap layer
4
is formed to extent along the top of the lower core layer
1
to the position of contact between the lower core layer
1
and the base end
10
b
of an upper core layer
10
which will be described below, as shown in FIG.
25
. On the other hand, the upper pole layer
5
is formed to extend to the top of a Gd determining layer
6
formed on the gap layer
4
. The gap layer
4
is made of a nonmetallic insulating material, for example, SiO
2
or the like.
As shown in
FIGS. 24 and 25
, an insulation layer
7
is formed on both sides of the upper pole layer
5
in the track width direction (the X direction shown in the drawings) and on the back side in the height direction (the Y direction shown in the drawings). Furthermore, a coil layer
13
is patterned in a spiral shape on the insulation layer
7
, and an insulation layer
9
made of an organic insulating material is formed on the coil layer
13
to cover the coil layer
13
.
The upper core layer
10
is formed on the insulation layer
9
, for example, by a frame plating method so that the front end
10
a
of the upper core layer
10
is magnetically connected to the upper pole layer
5
and exposed in the surface facing the recording medium. The base end
10
b
of the upper core layer
10
is magnetically connected to the lower core layer
1
.
As shown in
FIG. 24
, the entire front surface
10
c
of the upper core layer
10
is exposed in the surface facing the recording medium.
Next, the method of manufacturing the thin film magnetic head shown in
FIGS. 24 and 25
will be described below with reference to
FIGS. 26
to
32
. As shown in
FIG. 26
, the gap layer
4
made of an insulating material, for example, SiO
2
is formed over the entire surface of the lower core layer
1
, and a resist layer
11
having a trench
11
a
having the track width Tw is formed on the gap layer
4
. The trench
11
a
is formed with the predetermined length dimension from the surface facing the recording medium in the height direction (the Y direction shown in the drawing). Then, the upper pole layer
5
made of, for example, a NiFe alloy, is formed in the trench
11
a
by plating, and the resist layer
11
is removed.
As shown in
FIG. 27
, the width dimension of the upper pole layer
5
, i.e., the track width Tw, is, for example, 0.45 &mgr;m, and the height dimension is about 3.5 to 3.8 &mgr;m. In
FIG. 27
, both sides of the upper pole layer
5
in the track width direction (the X direction shown in the drawing) are etched by ion milling (trimming step). As shown in
FIG. 28
, the portions of the gap layer
4
which protrude from the width dimension of the upper pole layer
5
in the track width direction are removed by the ion milling, and portions of the upper surface of the lower core layer
1
on both sides of the upper pole layer
5
are also removed to form a protrusion
1
b
and inclined surfaces
1
a
at the top of the lower core layer
1
.
In
FIG. 29
, the insulation layer
7
of Al
2
O
3
or the like is formed to cover both sides of the upper pole layer
5
and the upper pole layer
5
on the lower core layer
1
, and polished to line A—A by a CMP technique or the like.
FIG. 30
shows the state after polishing.
Next, the coil layer
13
and the insulation layer
9
shown in
FIG. 25
are formed on the insulation layer
7
, and then a resist layer
12
is formed on the insulation layers
7
and
9
, and the upper pole layer
5
, as shown in
FIG. 31
(partial plan view). Then, a patterned portion
12
a
of the resist layer
12
is exposed and developed to remove the patterned portion
12
a.
Then, a magnetic material is plated in the patterned portion
12
a
, and the resist layer
12
is removed to complete the upper core layer
10
.
FIG. 32
shows the structure of the tip portion of the thin film magnetic head.
The trimming step is usually carried out twice, the first trimming step comprising ion irradiation at an angle as close to a right angle as possible with the film plane direction of the lower core layer
1
. In this step, the portions of the gap layer
4
on both sides of the bottom of the upper pole layer
5
are removed, and the lower core layer
1
formed below the gap layer
4
is also partially removed to form the protrusion
1
b
on the lower core layer
1
. This step causes a problem in which the magnetic powder produced by cutting the gap layer
4
and the lower core layer
1
again adheres to the sides of the upper pole layer
5
. Therefore, the second trimming step comprises ion irradiation in a direction more inclined that that in the first trimming step to remove the magnetic powder and, at the same time, to form the inclined surfaces
1
a
at the top of the lower core layer
1
on both sides of the upper pole layer
5
.
However, in the structure of the thin film magnetic head shown in
FIGS. 24 and 25
, the front end surface
10
c
of the upper core layer
10
having a width dimension larger than the track width Tw is exposed in the surface facing the recording medium, and thus side fringing occurs due to a magnetic leakage between the upper core layer
10
and the upper pole layer
5
, thereby causing the problem of decreasing the area recording density due to the occurrence of side fringing. Therefore, in order to manufacture a thin film magnetic head adaptable to a higher recording density in future, it is necessary to decrease the track width Tw and the occurrence of side fringing.
The method of manufacturing the thin film magnetic head shown in
FIGS. 24 and 25
comprises the trimming step which causes variations in the track width Tw and the shape, and the problem of significantly decreasing the height of the upper pole layer
5
. The reason for performing the trimming step is that in the state shown in
FIG. 27
, the gap layer
4
and the lower core layer
1
are formed to extend on both sides of the bottom of the upper pole layer
5
, thereby easily causing the occurrence of side fringing between the upper pole layer
5
and the lower core layer
1
. In the trimming, as shown in
FIG. 28
, the portions of the gap layer
4
which extend on both sides of the bottom of the upper pole layer
5
are removed, and the protrusion
1
b
and the inclined surfaces
1
a
are formed in the lower core layer
1
to increase the distance between the upper pole layer
5
and the lower core layer
1
, whereby the occurrence of side fringing can be possibly appropriately decreased.
However, the trimming step causes a variation in the amount of the magnetic powder adhering to both sides of the upper pole layer
5
and a variation in removal of the magnetic powder, and a significant decrease in the height of the upper pole layer
5
because the first trimming step comprises ion irradiation in the direction as close to a right angle as possible with the film plane direction of the lower core layer
1
. As a result, variations easily occur in the track width Tw and the shape of the upper pole layer
5
, and the height dimension of the upper pole layer
5
is significantly decreased to
Gochou Hideki
Ikegami Chiaki
Ikegami Masaki
Kobayashi Kiyoshi
Sato Kiyoshi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ikegami Chiaki
Klimowicz William
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