Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2003-01-21
2004-10-26
Letscher, George J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06809902
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thin film magnetic head and a method of manufacturing the thin film magnetic head.
An ordinary thin film magnetic head having a recording head section
10
and a reproducing head section
12
is shown in FIG.
6
.
An insulating layer
14
, which is made of, for example, alumina, is formed on a substrate
13
, which is made of, for example, a ceramic. A lower shielding layer
15
, which is made of, for example, FeNi, is formed on the insulating layer
14
. An insulating layer
16
, which is made of, for example, alumina, is formed on the lower shielding layer
15
. An SAL (soft adjacent layer)
17
, which is made of, for example, FeNi, is formed on the insulating layer
16
. A spacer layer
18
, which is made of, for example, tantalum, titanium, is formed on the SAL
17
.
A pair of terminals
19
and
20
are formed on the spacer layer
18
. An MR layer
21
, which is made of FeNi, is formed on the spacer layer
18
and located between the terminals
19
and
20
. An insulating layer
22
, which is made of, for example, alumina, is formed on the terminals
19
and
20
and the MR layer
21
. An upper shielding layer
23
, which is made of, for example, FeNi, is formed on the insulating layer
22
.
The insulating layer
14
, the lower shielding layer
15
, the insulating layer
16
the SAL
17
, the spacer layer
18
, the MR layer
21
, the terminals
19
and
20
, the insulating layer
22
and the upper shielding layer
23
, etc. constitute the reproducing head section
12
for reproducing data.
An insulating layer
24
, which is made of, foe example, alumina, is formed on the upper shielding layer
23
. A coil
25
is formed in the insulating layer
24
. An upper magnetic pole
26
is provided on the insulating layer
24
. A protection layer
27
, which is made of, for example, alumina, is formed on the upper magnetic pole
26
. The upper shielding layer
23
, the insulating layer
24
, the coil
25
, the upper magnetic pole
26
and the protection layer
27
, etc. constitute the recording head section
10
.
Note that, the upper shielding layer
23
also acts as a lower magnetic pole of the recording head section
10
.
FIG. 7
shows a sectional view of the recording head section
10
. The structure of the recording head section
10
will be explained with reference to FIG.
7
.
The lower magnetic pole
23
a
, which is made of FeNi, is formed on the substrate
23
(the upper shielding layer
23
) by plating. Thickness of the lower magnetic pole
23
a
is considerably thick, e.g., 6-7 &mgr;m, so the lower magnetic pole
23
a
cannot be formed by spattering; therefore, it is made by electrolytic plating.
An insulating layer
28
, which is made of, for example, alumina, is formed in a concave part
23
b
of the lower magnetic pole
23
a
and on the substrate
23
by spattering. The coil
25
is formed on the insulating layer
28
by plating.
The concave part
23
b
is filled with an insulating layer
29
, which is made of resist and which covers over the coil
25
.
A surface of the insulating layer
29
is flatly lapped until its level is made equal to that of the lower magnetic pole
23
a.
A high magnetic permeability layer
30
, which is made of a high magnetic permeability material, e.g., CoFeNi, whose magnetic permeability is higher than that of the lower magnetic pole
23
a
, is formed on a surface of the lower magnetic pole
23
a
located on the write-end side, which faces the upper magnetic pole
26
with a gap layer
31
. It is difficult to form the high magnetic permeability layer
30
by electrolytic plating; therefore, it is formed by spattering, and its thickness is about 0.5 &mgr;m.
By forming the high magnetic permeability layer
30
, a level difference is made between a surface of the high magnetic permeability layer
30
and a surface of the insulating layer
29
.
The gap layer
31
, which is made of, for example, SiO
2
, is formed on the surfaces of the high magnetic permeability layer
30
and the insulating layer
29
.
Next, an insulating layer
32
, which is made of resist, is formed on the gap layer
31
, to correspond to the insulating layer
29
and a part of the high magnetic permeability layer
30
adjacent to the insulating layer
29
.
By adjusting viscosity of the resist of the insulating layer
32
, an apex part
33
, whose thickness is made thinner toward the write-end (the left end in the drawing of FIG.
7
), is formed in the insulating layer
32
.
Next, the gap layer
31
and the insulating layer
32
are covered with resist so as to form a mask (not shown). Then, the upper magnetic pole
26
is formed by electrolytic plating. Further, the mask is removed, then the protection layer
27
is formed. By forming the protection layer
27
, the thin film magnetic head is completed.
In the above described conventional thin film magnetic head, the high magnetic permeability layer
30
is formed in the vicinity of the gap layer
31
so as to improve recording ability, and the apex part
33
of the insulating layer
32
is located on the high magnetic permeability layer
30
.
A distance “GD” between a front end of the apex part
33
and an end face of the gap layer
31
(or a disk-side face) is called a gap depth; and an inclination angle “&thgr;” of the apex part
33
is called an apex angle.
The gap depth GD and the apex angle &thgr; highly influence characteristics of recording data.
If the gap distance GD is short, leakage a magnetic field is reduced and loss of a recording magnetic field, which is generated on the disk-side face side, is reduced, so that an over-write characteristic of the recording characteristics can be improved. However, if the gap depth GD is too short, e.g., 0.2 &mgr;m or less, it is very difficult to correctly position a front end of the apex part
33
, and the deviation of the front end badly influences the recording characteristics. The optimum gap depth GD is determined by considering the recording characteristics and manufacturing efficiency of the thin film magnetic head.
The apex angle &thgr; should be wide so as to reduce the leakage magnetic field between the lower magnetic pole
23
and the upper magnetic pole
26
. However, if the apex angle &thgr; is too wide, it is difficult to form the upper magnetic pole
26
. Therefore, the optimum apex angle &thgr; is determined by considering the recording characteristics and manufacturing efficiency of the thin film magnetic head as well as the gap depth GD.
Preferably, the gap depth GD and the apex angle &thgr; are independently controlled so as to make the recording characteristics optimum.
However, it is very difficult to independently control the gap depth GD and the apex angle &thgr; by adjusting the viscosity of the resist forming the insulating layer
32
.
Namely, if the gap depth GD is changed, the apex angle &thgr; is simultaneously changed.
FIG. 8
is a graph showing a relationship between the gap depth GD and the apex angle &thgr;. As clearly shown in
FIG. 8
, the apex angle &thgr; is made wider when the gap depth GD is reduced. The variation is influenced by sorts and viscosity of the resist.
As described above, it is very difficult to manufacture the thin film magnetic heads without limiting the variation of the gap depth GD and the apex angle &thgr;, so that the variation of the recording characteristics of the thin film magnetic heads cannot be limited within a desired range.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thin film magnetic head having stable recording characteristics.
Another object of the present invention is to provide a method of manufacturing the thin film magnetic head, in which the gap depth GD and the apex angle &thgr; can be independently controlled.
To achieve the object, the present invention has following structures.
Namely, the thin film magnetic head of the present invention comprises: a lower magnetic pole; an upper magnetic pole; an insulating layer being formed between the lower magnetic pole and the upper magnetic pole, the insulating lay
Fujitsu Limited
Greer Burns & Crain Ltd.
Letscher George J.
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