Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-12-27
2004-06-08
Ometz, David (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S119050
Reexamination Certificate
active
06747851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head having at least one of an induction-type electromagnetic transducer and a magnetoresistive element, and to 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 areal 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 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 where areal density is more than 1 gigabit per square inch. A GMR head is used as a reproducing head where areal density is more than 3 gigabits per square inch. It is GMR heads that have been most widely used recently.
The performance of the reproducing head is improved by replacing the AMR film with a GMR film and the like having an excellent magnetoresistive sensitivity. Alternatively, a pattern width such as the reproducing track width and the MR height, in particular, may be optimized. The MR height is the length (height) between an end of the MR element located in the air bearing surface and the other end. The air bearing surface is a surface of the thin-film magnetic head facing toward a magnetic recording medium.
Performance improvements in a recording head are also required as the performance of a reproducing head is improved. It is required to increase the recording track density in order to increase the areal density among the performance characteristics of the 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 a submicron order. This width is one of the factors that determine the recording head performance. Semiconductor process techniques are utilized to implement such a structure. Another factor is a pattern width such as the throat height, in particular. The throat height is the length (height) of pole portions, that is, 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 by an amount of lapping when the air bearing surface is processed.
As thus described, it is important to fabricate well-balanced recording and reproducing heads to improve the performance of the thin-film magnetic head.
In order to implement a thin-film magnetic head that achieves high recording density, the requirements for the reproducing head include a reduction in reproducing track width, an increase in reproducing output, and a reduction in noise. The requirements for the recording head include a reduction in recording track width, an improvement in overwrite property that is a parameter indicating one of characteristics when data is written over existing data, and an improvement in nonlinear transition shift (NLTS).
Reference is now made to
FIG. 16A
to FIG.
22
A and
FIG. 16B
to
FIG. 22B
to describe an example of a manufacturing method of a related-art thin-film magnetic head element.
FIG. 16A
to
FIG. 22A
are cross sections each orthogonal to the air bearing surface.
FIG. 16B
to
FIG. 22B
are cross sections of the pole portions each parallel to the air bearing surface.
According to 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. Next, on the insulating layer
102
, a bottom shield layer
103
made of a magnetic material and having a thickness of 2 to 3 &mgr;m, for example, is formed for a reproducing head.
Next, as shown in FIG.
17
A and
FIG. 17B
, a shield gap film
104
a
made of an insulating material such as alumina and having a thickness of 10 to 20 nm, for example, is formed through sputtering, for example, on the bottom shield layer
103
. Next, a shield gap film
104
b
made of an insulating material such as alumina and having a thickness of 100 nm, for example, is formed through sputtering, for example, on the shield gap film
104
a
except a region where a GMR element described later will be formed. The shield gap film
104
b
is provided for preventing a short circuit between the GMR element and the bottom shield layer
103
.
Next, on the shield gap film
104
b
, a film having a thickness of 40 to 50 nm, for example, to make up the GMR element for reproduction is formed through a method such as sputtering. This film is etched with a photoresist pattern not shown as a mask to form the GMR element
105
.
Next, a pair of conductive layers (that may be called leads)
106
are formed by liftoff through the use of the above-mentioned photoresist pattern. The conductive layers
106
are electrically connected to the GMR element
105
. The photoresist pattern is then removed.
Next, as shown in FIG.
18
A and
FIG. 18B
, a shield gap film
107
a
made of an insulating material such as alumina and having a thickness of 10 to 20 nm, for example, is formed through sputtering, for example, on the shield gap films
104
a
and
104
b
, the GMR element
105
and the conductive layers
106
. The GMR element
105
is embedded in the shield gap films
104
a
and
107
a
. Next, a shield gap film
107
b
made of an insulating material such as alumina and having a thickness of 100 nm, for example, is formed through a method such as sputtering on the shield gap film
107
a
except the neighborhood of the GMR element
105
.
Next, as shown in FIG.
19
A and
FIG. 19B
, on the shield gap films
107
a
and
107
b
, a top-shield-layer-cum-bottom-pole-layer (called a top shield layer in the following description)
108
is formed. The top shield layer
108
has a thickness of about 3 &mgr;m and is made of a magnetic material and used for both the reproducing head and the recording head.
Next, as shown in FIG.
20
A and
FIG. 20B
, a recording gap layer
109
made of an insulating film such as an alumina film and having a thickness of 0.2 &mgr;m, for example, is formed on the top shield layer
108
. Next, a portion of the recording gap layer
109
located in the center of the region where a thin-film coil described later is to be formed is etched to form a contact hole for making a magnetic path. Next, a top pole tip
110
for the recording head is formed on the recording gap layer
109
in the pole portion. The top pole tip
110
is made of a magnetic material and has a thickness of 1.0 to 1.5 &mgr;m. At the same time, a magnetic layer
119
made of a magnetic material is formed for making the magnetic path in the contact hole for making the magnetic path.
Next, the recording gap layer
109
and a part of the top shield layer
108
are etched through ion milling, using the top pole tip
110
as a mask. As shown in
FIG. 20B
, the structure is called a trim structure wherein the sidewalls of the top pole portion (the top pole tip
110
), the recording gap layer
109
, and a part of the top shield layer
108
are formed vertically in a self-aligned manner.
Next, an insulating layer
111
of alumina, for example, having a thickness of about 3 &mgr;m is formed over the entire surface. The insulating layer
111
is polished to the surfaces of the top pole tip
110
and
Inoue Tohru
Sasaki Yoshitaka
Oliff & Berridg,e PLC
Ometz David
TDK Corporation
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