Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-03-22
2002-09-24
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06456461
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads and manufacturing methods therefore, and more particularly, relates to a thin-film magnetic head for a track width of not more than 1 &mgr;m and a suitable technique for a manufacturing method therefor.
2. Description of the Related Art
FIG. 36
is a perspective view showing a magnetic head
150
provided with a conventional hybrid thin-film magnetic head in a slider, and
FIG. 37
is a cross-sectional view of the magnetic head
150
shown in FIG.
36
.
This floating-type magnetic head
150
, as shown in
FIG. 36
, is primarily composed of a slider
151
and a hybrid thin-film magnetic head
157
provided in the slider
151
. Reference numeral
155
indicates a leading side of the slider
151
which is an upstream side of the direction of motion of a magnetic reading medium, and reference numeral
156
indicates a trailing side which is a downstream side of the direction of motion of the magnetic recording medium. In a medium-opposing face
152
of the slider
151
opposing the magnetic recording medium, rails
151
a,
151
b,
and
151
a,
are formed, and air grooves
151
c
and
151
c
are formed between the individual rails.
The hybrid thin-film magnetic head
157
is provided at a side wall
151
d
at the trailing side
156
of the slider
151
.
FIG. 38
is a perspective view showing the hybrid thin-film magnetic head
157
.
As shown in
FIGS. 37 and 38
, the hybrid thin-film magnetic head
157
is composed of a magnetoresistive (MR) magnetic head h
1
provided with a magnetoresistive element and a thin-film magnetic head h
2
as a writing head, both of which are formed in a layered structure on the side wall
151
d
of the slider
151
.
As shown in
FIGS. 37 and 38
, the MR magnetic head h
1
is composed of a lower shield layer
163
composed of a magnetic alloy and formed on the side wall
151
d
of the slider
151
, a reading gap layer
164
formed on the lower shield layer
163
, a magnetoresistive element
165
, a part of which is exposed at the medium-opposing face
152
, an upper gap layer
166
covering the magnetoresistive element
165
and the reading gap layer
164
, and an upper shield layer
167
covering the upper gap layer
166
.
The upper shield layer
167
is also used as a lower core layer for the thin-film magnetic head h
2
.
The MR magnetic head hi described above is used as a reading head, in which resistance of the magnetoresistive element
165
changes upon application of a minute leakage magnetic field from the magnetic recording medium, and voltage changes in accordance with these resistance changes are read as read signals of the magnetic recording medium.
The thin-film magnetic head h
2
is composed of a lower core layer (the upper shield layer)
167
, a gap layer
174
formed on the lower core layer
167
, a coil
176
formed on the gap layer
174
in a back region Y, an upper insulating layer
177
covering the coil
176
, and an upper core layer
178
joined to the gap layer
174
in a magnetic pole region X and to the lower core layer
167
in the back region Y.
The coil
176
is patterned in a planar spiral form. A base terminal portion
178
b
of the upper core layer
178
is magnetically coupled to the lower core layer
167
approximately at the center of the coil
176
.
A protective layer
179
composed of alumina or the like is formed on the upper core layer
178
.
The lower core layer
167
, the gap layer
174
, and the upper core layer
178
are disposed from the back region Y to the magnetic pole region X in the hybrid thin-film magnetic head
157
, and are exposed at the medium-opposing face
152
. At the medium-opposing face
152
, the upper core layer
178
and the lower core layer
167
oppose each other with the gap layer
174
therebetween so as to form a magnetic gap.
As shown in
FIG. 37
, the magnetic pole region X is a region in which the upper core layer
178
and the lower core layer
167
oppose each other only with the gap layer
174
therebetween in the vicinity of the medium-opposing face
152
, and the back region Y is a region other than the magnetic pole region X.
The thin-film magnetic head h
2
described above is used as a writing head, in which, upon application of a writing current to the coil
176
, a magnetic flux is generated in the upper core layer
178
and the lower core layer
167
by this writing current, the magnetic flux leaking from the magnetic gap generates a leakage magnetic field, and write signals are written by magnetizing the magnetic recording medium with a leakage magnetic field.
When the thin-film magnetic head h
2
described above is manufactured, the lower core layer
167
, the gap layer
174
, and the upper core layer
178
are sequentially formed and patterned beforehand. The upper core layer
178
is formed by plating using flame plating followed by ion-milling, the width of the upper core layer
178
exposed at the medium-opposing face
152
is defined by a resist width for the flame plating or the like, plating, and etching, and the width of a magnetic recording track is defined by the width of the upper core layer
178
exposed at the medium-opposing face
152
.
When the width of the magnetic recording medium (the width of the upper core layer
178
exposed at the medium-opposing face
152
in the magnetic pole region) of the thin-film magnetic head h
2
is set to be small, the track width of the magnetic recording medium can be reduced, the track density of the magnetic recording medium can be increased, and the recording density can therefore be increased.
However, in the conventional thin-film magnetic head h
2
, there is a problem in that the writing density of the magnetic recording medium cannot be further improved because the upper core layer is thick. The reason for this is that, even though the layers are precisely formed by using flame plating and the like and the magnetic pole region is processed with the most advanced processing accuracy currently available, it is difficult for the width of the magnetic recording track to be not more than 1 &mgr;m due to a limitation of exposure resolution during pattern forming of the resist.
In addition, when a width of a magnetic recording track is set to be small, the lower core layer
167
and the upper core layer
178
, with the gap layer
174
therebetween, at the ends of magnetic pole region X at the back region Y side, i.e., the depth of the magnetic gap from the medium-opposing face
152
, the gap depth Gd may not be parallel to the medium-opposing face
152
in some cases, and as a result, a leakage magnetic field is increased, the writing capability of the thin-film magnetic head h
2
may be lowered, the gap depth Gd may vary, and variation of the writing capability of the thin-film magnetic head h
2
may occur. Accordingly, there is a requirement for precisely defining the position of the gap depth Gd.
SUMMARY OF THE INVENTION
Accordingly, taking the problems described above into consideration, the present invention is to achieve the following objects.
(1) To provide a thin-film magnetic head for a width of a magnetic recording track of not more than 1 &mgr;m, corresponding to a track width of not more than 1 &mgr;m.
(2) To improve accuracy in setting the position of a gap depth, i.e., a depth of the magnetic recording track from a medium-opposing face, in the magnetic head described above.
(3) To provide a method for manufacturing a thin-film magnetic head for a width of a magnetic recording track of not more than 1 &mgr;m.
In order to achieve the objects described above, the following structure according to the present invention is employed.
A thin-film magnetic head of the present invention has a structure comprising an upper core layer, a lower core layer, a coil, a gap layer, in which the upper core layer and the lower core layer extend from a back region toward a magnetic pole region, ends of the upper core layer and the lower core layer are exposed at a medium-opposing face, the upper core layer and the lower
Alps Electric Co. LTD
Brinks Hofer Gilson & Lione
Watko Julie Anne
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