Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-03-21
2002-12-03
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06490126
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head comprising at least an induction-type magnetic transducer and a method of manufacturing such a thin-film magnetic head.
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. Composite thin-film magnetic heads 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. MR elements include an anisotropic magnetoresistive (AMR) element that utilizes the AMR effect and a giant magnetoresistive (GMR) element that utilizes the GMR effect. A reproducing head using an AMR element is called an AMR head or simply an MR head. A reproducing head using a GMR element is called a GMR head. An AMR head is used as a reproducing head whose surface recording density is more than 1 gigabit per square inch. A GMR head is used as a reproducing head whose surface recording density is more than 3 gigabits per square inch.
The performance of the reproducing head is improved by replacing the AMR film with a GMR film and the like with an excellent magnetoresistive sensitivity. Alternatively, a pattern width such as an MR height, in particular, may be optimized. The MR height is the length (height) between an end of the MR element closer to the air bearing surface and the other end. The MR height is controlled by an amount of lapping when the air bearing surface is processed. The air bearing surface is a surface of the thin-film magnetic head facing toward a magnetic recording medium and may be called a track surface, too.
Performance improvements in a recording head are also required as the performance of a reproducing head is improved. One of the factors that determine the recording head performance is a pattern width such as a throat height (TH), in particular. 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. A reduction in throat height is desired in order to improve the recording head performance. The throat height is controlled as well by an amount of lapping when the air bearing surface is processed.
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 a submicron order. Semiconductor process techniques are utilized to implement such a structure.
As thus described, it is important to fabricate well-balanced recording and reproducing heads to improve the performance of a thin-film magnetic head.
Reference is now made to
FIG. 16A
to
FIG. 21A
,
FIG. 16B
to
FIG. 21B
, and
FIG. 22
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. 16A
to
FIG. 21A
are cross sections each orthogonal to the air bearing surface of the thin-film magnetic head.
FIG. 16B
to
FIG. 21B
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.
16
A and
FIG. 16B
, 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, as shown in FIG.
17
A and
FIG. 17B
, 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 film having a thickness of tens of nanometers is formed for making an MR element
105
for reproduction. Next, on the MR film a photoresist pattern is selectively formed where the MR element
105
is to be formed. The photoresist pattern is formed into a shape that facilitates lift-off, such as a shape having a T-shaped cross section. Next, with the photoresist pattern as a mask, the MR film is etched through ion milling, for example, to form the MR element
105
. The MR element
105
may be either a GMR element or an AMR element. Next, on the bottom shield gap film
104
, a pair of electrode layers
106
are formed, using the photoresist pattern as a mask. 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 top-shield-layer-cum-bottom-pole-layer (called a bottom pole layer in the following description)
108
having a thickness of about 3 &mgr;m is formed. The bottom pole layer
108
is made of a magnetic material and used for both a reproducing head and a recording head. Next, 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, as shown in FIG.
18
A and
FIG. 18B
, a portion of the recording gap layer
109
is etched to form a contact hole
119
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 such as Permalloy (NiFe) or FeN as a high saturation flux density 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.
19
A and
FIG. 19B
, 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. 19B
, 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 part of the bottom pole layer
108
are formed vertically in a self-aligned manner. The trim structure suppresses an increase in the effective track width due to expansion of a magnetic flux generated during writing in a narrow track.
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. The polishing method may be mechanical polishing or chemical mechanical polishing (CMP). Through this polishing, the surfaces of the top pole tip
110
and the magnetic layer
119
are exposed.
Next, as shown in FIG.
20
A and
FIG. 20B
, on the flattened insulating layer
111
, a thin-film coil
112
of a first layer is made of copper (Cu), for example, for the induction-type recording head. Next, a photoresist layer
113
is formed into a specific pattern on the insulating layer
111
and the coil
112
. Heat treatment is then performed to flatten the surface of the photoresist layer
113
. On the photoresist layer
113
, a thin-film coil
114
of a second layer is then formed. Next, a photoresist layer
115
is formed into a specific pattern on the photoresist layer
113
and the coil
114
. Heat treatment is then performed to flatten the surface of the photoresist layer
115
.
Next, as shown in FIG.
21
A and
FIG. 21B
, a top pole layer
116
is formed for the recording head on the top
Davis David
Oliff & Berridg,e PLC
TDK Corporation
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