Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-05-18
2002-11-05
Ometz, David L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Head
Core
C360S317000
Reexamination Certificate
active
06477006
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads and methods for making the same. In particular, the present invention relates to a thin-film magnetic head for a track width of 1 &mgr;m or less and to a method for making the same.
2. Description of the Related Art
FIGS. 51 and 52
are a perspective view and a cross-sectional view, respectively, of a conventional floating thin-film magnetic head
150
. The floating thin-film magnetic head
150
has a slider
151
and a combined thin-film magnetic head
157
. Numeral
155
represents a leading side which is upstream of the moving direction of the slider
151
on a recording medium and numeral
156
represent a trailing side which is downstream of the moving direction. The slider
151
has an opposing face
152
which opposes the magnetic recording media, and the opposing face
152
has rails
151
a
and
151
b
which form air grooves
151
c
and
151
c
therebetween. The combined thin-film magnetic head
157
is provided on a trailing end
151
d
of the slider
151
.
FIG. 53
is a perspective view of the combined thin-film magnetic head
157
. With reference to
FIGS. 52 and 53
, the combined thin-film magnetic head
157
has a MR head h
1
including a magnetoresistive element and a thin-film magnetic write head h
2
deposited on the trailing end
151
d
of the slider
151
.
The MR head h
1
includes a lower shielding layer
163
composed of a magnetic alloy formed on the trailing end
151
d
of the slider
151
, a lower gap layer
164
deposited on the lower shielding layer
163
, a magnetoresistive element
165
partly exposed at the opposing face
152
, an upper gap layer
166
covering the magnetoresistive element
165
and the lower gap layer
164
, and an upper shielding layer
167
covering the upper gap layer
166
. The upper shielding layer
167
also functions as a lower core layer of the thin-film magnetic write head h
2
.
The MR head h
1
is used as a reading head. When a small fringing magnetic field from a recording magnetic medium is applied to the MR head h
1
, the resistance of the magnetoresistive element
165
changes. The MR head h
1
detects a change in voltage based on the change in the resistance as reading signals from the magnetic recording medium.
The thin-film magnetic write head h
2
includes the upper shielding layer or lower core layer
167
, a gap layer
174
deposited on the upper shielding layer
167
, a coil
176
formed in a back region Y of the gap layer
174
, an upper insulating layer
177
covering the coil
176
, and an upper core layer
178
which connects to the gap layer
174
in a magnetic pole end region X and to the upper shielding layer
167
in the back region Y.
The coil
176
has a planar spiral pattern. A bottom end
178
c
of the upper core layer
178
is magnetically coupled to the upper shielding layer
167
substantially in the center of the coil
176
. The upper core layer
178
is covered with a protective layer
179
composed of alumina or the like.
The upper shielding layer
167
, the gap layer
174
, and the upper core layer
178
extend from the back region Y to the magnetic pole end region X and are exposed at the opposing face
152
. The opposing face
152
has a magnetic gap of the gap layer
174
interposed between the upper core layer
178
and the upper shielding layer
167
.
As shown in
FIG. 52
, in the magnetic pole end region X, the gap layer
174
is interposed between the upper core layer
178
and the lower core layer
167
in the vicinity of the opposing face
152
. The back region Y lies behind the magnetic pole end region X.
The thin-film magnetic head h
2
is a write head. When a recording current is applied to the coil
176
, the recording current produces a magnetic flux in the upper core layer
178
and the upper shielding layer
167
. The magnetic flux leaks as a fringing magnetic field from the magnetic gap toward the exterior. The fringing magnetic field magnetizes a magnetic recording medium to record signals.
In the production of the thin-film magnetic write head h
2
. however, the upper shielding layer
167
and the gap layer
174
are formed, and then the upper core layer
178
is formed by frame plating or the like so that the width thereof corresponds to the magnetic recording track width at the opposing face
152
. The magnetic recording track width on the media can be reduced by decreasing t he magnetic recording track width of the thin-film magnetic write head h
2
, that is, the width of the upper core layer
178
exposed at the opposing face
152
at the magnetic pole end region. As a result, the track density on the magnetic recording medium and thus the recording density are improved.
When the magnetic recording track width is designed to be 1 &mgr;m or less for high-density recording in the above thin-film magnetic head, the thickness of the laminate of the upper core layer
178
, the gap layer
174
, and the lower core layer
167
is significantly large with respect to the magnetic recording track width . If the thick laminate structure including the narrow upper core layer
178
is simultaneously formed by frame plating, the focal depth of exposure light is not matched during the formation of a resist frame, resulting in decreased resolution. Thus, the width of the upper core layer
178
is not constant at the edge, and a desired track width is not formed.
In order to achieve high-density recording by forming a magnetic recording track width of 1 &mgr;m or less, a configuration shown in
FIG. 54
is disclosed in U.S. Pat. Nos. 5,452,164 and 5,652,687.
FIG. 55
is an enlarged perspective view of a portion A in the magnetic pole end region X in the production process of a thin-film magnetic head
257
shown in
FIG. 54. A
groove
43
extending from the opposing face
152
is formed in an insulating layer
244
. With reference to
FIG. 56
, a lower magnetic pole layer
167
b
as a part of the lower core layer
167
, the gap layer
174
, and an upper magnetic pole layer
178
b
as a part of the upper core layer
178
are deposited in that order by an electroplating process in the groove
43
to form the magnetic gap. The magnetic recording track width is controlled by determining the width of the groove
43
.
The upper core layer
178
is connected to the upper magnetic pole layer
178
b
to complete a configuration shown in
FIGS. 57 and 58
, wherein
FIG. 57
is a front view of the thin-film magnetic head
257
shown in
FIG. 54
when viewed from the opposing face
152
, and
FIG. 58
is an enlarged cross-sectional view of the portion A of the thin-film magnetic head
257
in FIG.
54
. As shown in
FIG. 58
, an edge portion of the lower magnetic pole layer
167
b
and the upper magnetic pole layer
178
b
at the back region Y defines a gap depth Gd.
As described above, the magnetic recording track width on the media can be reduced and recording densities on the magnetic recording media can be increased by decreasing the recording track width, that is, the width of the lower magnetic pole layer
167
b,
the gap layer
174
, and the upper magnetic pole layer
178
b.
In the conventional thin-film magnetic write head h
2
, the lower magnetic pole layer
167
b,
the gap layer
174
, and the upper magnetic pole layer
178
b
are deposited by electroplating in the groove
43
. Thus, components for these layers are limited to materials which can be deposited by electroplating. On the other hand, use of high-performance magnetic materials for thin-film magnetic heads are required for achieving higher recording densities and miniaturization of magnetic recording media. In particular, a magnetic gap width of 1 &mgr;m or less is required for achieving higher recording densities of magnetic recording media.
When the magnetic recording track width is decreased, as shown in
FIG. 56
, the face at the gap depth Gd is not necessarily formed to be parallel to the opposing face
152
. With reference to
FIG. 54
, the groove
43
is generally formed in the insulating layer
244
by chemi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ometz David L.
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