Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-05-31
2003-11-04
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06643095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head having at least an induction-type magnetic transducer and a method of manufacturing such a thin-film magnetic head, and to a thin-film coil element incorporated in a thin-film magnetic head and so on and a method of manufacturing such a thin-film coil element.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought as surface recording density of hard disk drives has increased. Such thin-film magnetic heads include composite thin-film magnetic heads that have been widely used. A composite head is made of a layered structure including a recording head having an induction-type magnetic transducer for writing and a reproducing head having a magnetoresistive (MR) element for reading.
It is required to increase the track density on a magnetic recording medium in order to increase recording density among the performance characteristics of a recording head. To achieve this, it is required to implement a recording head of a narrow track structure wherein the width of top and bottom poles sandwiching the recording gap layer on a side of the air bearing surface is reduced down to microns or the order of submicron. Semiconductor process techniques are utilized to implement such a structure.
Reference is now made to
FIG. 13A
to
FIG. 16A
,
FIG. 13B
to FIG.
16
B and
FIG. 17
to describe an example of a method of manufacturing a composite thin-film magnetic head as an example of a related-art method of manufacturing a thin-film magnetic head.
FIG. 13A
to
FIG. 16A
are cross sections each orthogonal to an air bearing surface of the thin-film magnetic head.
FIG. 13B
to
FIG. 16B
are cross sections of a pole portion of the head each parallel to the air bearing surface.
In the manufacturing method, as shown in FIG.
13
A and
FIG. 13B
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, having a thickness of about 5 to 10 &mgr;m is deposited on a substrate
101
made of aluminum oxide and titanium carbide (Al
2
O
3
—TiC), for example. On the insulating layer
102
a bottom shield layer
103
made of a magnetic material is formed for making a reproducing head.
Next, on the bottom shield layer
103
, alumina, for example, is deposited to a thickness of 100 to 200 nm through sputtering to form a bottom shield gap film
104
as an insulating layer. On the bottom shield gap film
104
an MR element
105
for reproduction having a thickness of tens of nanometers is formed. Next, a pair of electrode layers
106
are formed on the bottom shield gap film
104
. The electrode layers
106
are electrically connected to the MR element
105
.
Next, a top shield gap film
107
is formed as an insulating layer on the bottom shield gap film
104
and the MR element
105
. The MR element
105
is embedded in the shield gap films
104
and
107
.
Next, on the top shield gap film
107
, a bottom pole layer
108
that also functions as a top shield layer, having a thickness of about 3 &mgr;m, is formed. The bottom pole layer
108
is made of a magnetic material and is used for both a reproducing head and a recording head.
Next, as shown in FIG.
14
A and
FIG. 14B
, on the bottom pole layer
108
, a recording gap layer
109
made of an insulating film such as an alumina film whose thickness is 0.2 &mgr;m is formed. Next, a portion of the recording gap layer
109
is etched to form a contact hole
109
a
to make a magnetic path. On the recording gap layer
109
in the pole portion, a top pole tip
110
made of a magnetic material and having a thickness of 0.5 to 1.0 &mgr;m is formed for the recording head. At the same time, a magnetic layer
119
made of a magnetic material is formed for making the magnetic path in the contact hole
109
a
for making the magnetic path.
Next, as shown in FIG.
15
A and
FIG. 15B
, the recording gap layer
109
and the bottom pole layer
108
are etched through ion milling, using the top pole tip
110
as a mask. As shown in
FIG. 15B
, the structure is called a trim structure wherein the sidewalls of the top pole (the top pole tip
110
), the recording gap layer
109
, and a part of the bottom pole layer
108
are formed vertically in a self-aligned manner.
Next, an insulating layer
111
made of an alumina film, for example, and having a thickness of about 3 &mgr;m is formed on the entire surface. The insulating layer
111
is then polished to the surfaces of the top pole tip
110
and the magnetic layer
119
and flattened.
Next, on the flattened insulating layer
111
, a first layer
112
of a thin-film coil is made of copper (Cu), for example, for the induction-type recording head. Next, a photoresist layer
113
is formed into a specific shape on the insulating layer
111
and the first layer
112
. Heat treatment is then performed at a specific temperature to flatten the surface of the photoresist layer
113
. On the photoresist layer
113
, a second layer
114
of the thin-film coil is then formed. Next, a photoresist layer
115
is formed into a specific shape on the photoresist layer
113
and the second layer
114
. Heat treatment is then performed at a specific temperature to flatten the surface of the photoresist layer
115
.
Next, as shown in FIG.
16
A and
FIG. 16B
, a top pole layer
116
is formed for the recording head on the top pole tip
110
, the photoresist layers
113
and
115
, and the magnetic layer
119
. The top pole layer
116
is made of a magnetic material such as Permalloy. Next, an overcoat layer
117
of alumina, for example, is formed to cover the top pole layer
116
. Finally, machine processing of the slider is performed to form the air bearing surface
118
of the thin-film magnetic head including the recording head and the reproducing head. The thin-film magnetic head is thus completed.
FIG. 17
is a top view of the thin-film magnetic head shown in FIG.
16
A and FIG.
16
B. The overcoat layer
117
and the other insulating layers and insulating films are omitted in FIG.
17
.
In
FIG. 16A
, ‘TH’ indicates the throat height and ‘MR-H’ indicates the MR height. The throat height is the length (height) of portions of magnetic pole layers facing each other with a recording gap layer in between, between the air-bearing-surface-side end and the other end. The MR height is the length (height) between the air-bearing-surface-side end of the MR element and the other end. In
FIG. 16B
, ‘P
2
W’ indicates the pole width, that is, the recording track width. In addition to the throat height, the MR height and so on, the apex angle as indicated with &thgr; in
FIG. 16A
is one of the factors that determine the performance of a thin-film magnetic head. The apex is a hill-like raised portion of the coil covered with the photoresist layers
113
and
115
. The apex angle is the angle formed between the top surface of the insulating layer
111
and the straight line drawn through the edges of the pole-side lateral walls of the apex.
In order to improve the performance of the thin-film magnetic head, it is important to precisely form throat height TH, MR height MR-H, apex angle &thgr;, and track width P
2
W as shown in FIG.
16
A and FIG.
16
B.
To achieve high surface recording density, that is, to fabricate a recording head with a narrow track structure, it has been particularly required that track width P
2
W fall within the submicron order of 1.0 &mgr;m or less. It is therefore required to process the top pole into the submicron order through semiconductor process techniques.
A problem is that it is difficult to form the top pole layer on the apex into small dimensions.
As disclosed in Published Unexamined Japanese Patent Application Hei 7-262519 (1995), for example, frame plating may be used as a method for fabricating the top pole layer. In this case, a thin electrode film made of Permalloy, for example, is formed by sputtering, for example, to fully cover the apex. Next, a photoresist is applied to the top of the electrode film and patterned through a photolithography
Davis David
Oliff & Berridg,e PLC
TDK Corporation
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