Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-07-11
2004-06-15
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06751054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads for use in magnetic disc apparatuses, magnetic tape apparatuses, and the like for recording information on magnetic recording media by a perpendicular magnetic recording method.
2. Description of the Related Art
FIGS. 17
to
24
are views for illustrating conventional thin-film magnetic heads for perpendicular magnetic recording. As shown in
FIG. 17
, a thin-film magnetic head
31
for perpendicular magnetic recording has a structure in which a nonmagnetic layer
33
composed of Al
2
O
3
and a thick magnetic layer
34
composed of a soft magnetic material such as a Fe—Ni-based alloy (permalloy) are formed on a substrate
32
composed of a nonmagnetic material such as an Al
2
O
3
—TiC ceramic. A thin magnetic layer
35
composed of a soft magnetic material such as a Fe—Ni-based alloy is formed on the nonmagnetic layer
33
and the thick magnetic layer
34
. An insulating layer
36
composed of an inorganic insulating material and a conductive coil layer
37
in a spiral shape composed of a low-resistance conductive material such as Cu are sequentially formed in this order on the thin magnetic layer
35
. An insulating layer
38
composed of an inorganic insulating material is formed on the insulating layer
36
so as to cover the conductive coil layer
37
, and an auxiliary magnetic pole layer
39
, composed of a soft magnetic material such as a Fe—Ni alloy, is formed on the insulating layer
38
and is magnetically coupled with the thin magnetic layer
35
at the back end portion thereof.
In addition, the thick magnetic layer
34
and the thin magnetic layer
35
form a main magnetic pole layer
40
. The individual front end surfaces of the substrate
32
, the nonmagnetic layer
33
, the thin magnetic layer
34
, the insulating layers
36
and
38
, and the auxiliary magnetic pole layer
39
form a medium-opposing surface
41
which opposes a magnetic recording medium
42
. As shown in
FIG. 18
, a narrow width of a front end portion
35
a
of the thin magnetic layer
35
formed on the nonmagnetic layer
33
has a track width Tw.
As shown in
FIG. 17
, the magnetic recording medium
42
, on which information is recorded by the thin-film magnetic head
31
for perpendicular magnetic recording, has a multilayer structure composed of a substrate
43
and a perpendicular magnetizing layer
45
, with a soft magnetic layer
44
having high permeability provided therebetween.
In the structure of the thin-film magnetic head
31
for perpendicular magnetic recording and the magnetic recording medium
42
shown in
FIG. 17
, when a recording current is applied to the conductive coil layer
37
, magnetic flux is generated in accordance with the recording current, and the magnetic flux flows in a magnetic circuit formed of the auxiliary magnetic pole layer
39
, the main magnetic pole layer
40
, the perpendicular magnetizing layer
45
, and the soft magnetic layer
44
having high permeability. This magnetizes the perpendicular magnetizing layer
45
of the magnetic recording medium
42
at a part thereof opposing the end surface of the thin magnetic layer
35
of the main magnetic pole layer
40
, whereby information is recorded on the magnetic recording medium
42
.
The thin-film magnetic head
31
for perpendicular magnetic recording is manufactured by, as shown in
FIG. 19
, first forming the thick magnetic layer
34
by electroplating on the substrate
32
other than an area from the edge to a slightly inner side thereof, and, as shown in
FIG. 20
, then forming the nonmagnetic layer
33
on the thick magnetic layer
34
and on the substrate
32
at which the thick magnetic layer
34
is not formed. Subsequently, as shown in
FIG. 21
, the nonmagnetic layer
33
and the thick magnetic layer
34
are polished by a chemical mechanical polishing method (hereinafter referred to as a CMP method) so that the nonmagnetic layer
33
and the thick magnetic layer
34
have the same thickness.
Next, as shown in
FIG. 22
, on the nonmagnetic layer
33
and the thick magnetic layer
34
, the thin magnetic layer
35
is formed by sputtering, and as shown in
FIG. 23
, the insulating layer
36
is then formed on the thin magnetic layer
35
. On the insulating layer
36
, an underlying layer for plating (not shown) and a resist layer
46
are sequentially formed. Subsequently, a pattern
46
a
corresponding to the conductive coil layer
37
is formed in the resist layer
46
by a photolithographic technique, and electroplating is then performed thereon to thereby form the conductive coil layer
37
on the insulating layer
36
.
Next, as shown in
FIG. 24
, the resist layer
46
and the underlying layer for plating are removed. The insulating layer
38
is then formed on the insulating layer
36
so as to cover the conductive coil layer
37
, and the auxiliary magnetic pole layer
39
is formed on the insulating layer
38
by using an electroplating method and a photolithographic technique, whereby the thin-film magnetic head
31
for perpendicular magnetic recording is formed.
In the conventional thin-film magnetic head
31
for perpendicular magnetic recording described above, the insulating layer
36
must be formed flat before the conductive coil layer
37
is formed by a photolithographic technique. The nonmagnetic layer
33
and the thick magnetic layer
34
, whose shapes influence the shape of the insulating layer
36
, are therefore planarized by polishing using a CMP method. However, due to variations in machining accuracy, the thick magnetic layer
34
constituting the main magnetic pole layer
40
may be polished by more than a predetermined amount. As a result, when a recording current is applied to the conductive coil layer
37
, the main magnetic pole layer
40
may be placed in a state of magnetic flux saturation, thereby decreasing the amount of magnetic flux concentrated on the front end portion
35
a
of the thin magnetic layer
35
constituting the main magnetic pole layer
40
. As a result, a problem may arise in that information cannot be recorded on the magnetic recording medium
42
.
In addition, and as shown in
FIG. 17
, since distance A between the conductive coil layer
37
and the front end portion
35
a
of the main magnetic pole layer
40
is relatively long, it is difficult to ensure sufficient magnetic flux concentrated on the front end surface of the thin magnetic layer
35
of the main magnetic pole layer
40
. As a result, a problem may arise in that the magnetic efficiency of the magnetic circuit described above is decreased. The problem described above can be solved by decreasing the distance A and by providing a part of the conductive coil layer
37
on a part of the insulating layer
36
corresponding to the front end portion
35
a
of the thin magnetic layer
35
. However, since the part of the insulating layer
36
mentioned above has a step portion
36
a
in conformity with the shape of the front end portion
35
a
of the thin magnetic layer
35
, when the pattern
46
a
is formed in the resist layer
46
by a photolithographic technique, light exposing the resist layer
46
reflects diffusely at the step portion
36
a
, and the pattern
46
a
is distorted, whereby the cross-sectional shape and the intervals of the conductive coil layer
37
are damaged. As a result, the characteristics of information recording on the magnetic recording medium
42
are adversely influenced.
SUMMARY OF THE INVENTION
The present invention was made in view of the problems of the conventional thin-film magnetic heads described above. An object of the present invention is to provide a thin-film magnetic head for perpendicular magnetic recording, which can concentrate sufficient magnetic flux for recording on an front end portion of a main magnetic pole layer when recording is performed, and which has a magnetic circuit having superior magnetic efficiency.
To these ends, a thin-film magnetic head for perpendicular magnetic recording of the present invention comprises
Kuriyama Toshihiro
Sato Kiyoshi
Watanabe Toshinori
Alps Electric Co. ,Ltd.
Tupper Robert S.
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