Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-01-10
2004-05-04
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235800, C360S235700, C360S236100
Reexamination Certificate
active
06731464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slider of a thin-film magnetic head which comprises a medium facing surface that faces toward a recording medium and a thin-film magnetic head element located near the medium facing surface, and to a method of manufacturing such a slider.
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-type electromagnetic transducer for writing and a reproducing head having a magnetoresistive element (that may be hereinafter called an 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 recording density is more than 1 gigabit per square inch. A GMR head is used as a reproducing head where areal recording density is more than 3 gigabits per square inch. It is GMR heads that have been most widely used recently.
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 recording 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. Semiconductor process techniques are utilized to implement such a structure. A pattern width, such as the throat height in particular, is also a factor that determines the recording head performance. 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. To achieve improvement in the recording head performance, it is desirable to reduce the throat height. 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.
In general, a flying-type thin-film magnetic head used in a hard disk drive and the like is made up of a slider having a thin-film magnetic head element formed at the trailing edge thereof. The slider slightly flies over a recording medium by means of airflow generated by the rotation of the medium.
Reference is now made to
FIGS. 65
to
67
to describe an example of a method of manufacturing a related-art thin-film magnetic head element.
FIG. 65
is a cross section orthogonal to the air bearing surface.
FIG. 66
is a cross section of the thin-film magnetic head element parallel to the air bearing surface.
FIG. 67
is a top view of the thin-film magnetic head element.
According to the manufacturing method, an insulating layer
102
made of alumina (Al
2
O
3
), for example, is first formed 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
of a magnetic material is formed for a reproducing head. Next, a bottom shield gap film
104
of an insulating material such as alumina is formed on the bottom shield layer
103
. An MR element
105
for reproduction is then formed on the bottom shield gap film
104
. On the bottom shield gap film
104
, a pair of electrode layers
106
are formed to be electrically connected to the MR element
105
. Next, a top shield gap film
107
of an insulating material such as alumina is formed on the bottom shield gap film
104
, the MR element
105
and the electrode layers
106
. The MR element
105
is embedded in the shield gap films
104
and
107
.
Next, a top-shield-layer-cum-bottom-pole layer (called a bottom pole layer in the following description)
108
is formed on the top shield gap film
107
. The bottom pole layer
108
is made of a magnetic material and used for both the reproducing head and the recording head. A recording gap layer
109
of an insulating film such as an alumina film is then formed on the bottom pole layer
108
. Next, the recording gap layer
109
is partially etched to form a contact hole for making a magnetic path. A top pole tip
110
of a magnetic material is then formed for the recording head on the recording gap layer
109
in the pole portion. At the same time, a magnetic layer
119
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 the bottom pole layer
108
are etched through ion milling, using the top pole tip
110
as a mask. As shown in
FIG. 66
, 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 bottom pole layer
108
are formed vertically in a self-aligned manner. Next, an insulating layer
111
made of an alumina film, for example, is formed over the entire surface. The insulating layer
111
is then lapped to the surfaces of the top pole tip
110
and the magnetic layer
119
and flattened.
On the flattened insulating layer
111
, a first layer
112
of a thin-film coil, made of copper (Cu), for example, is formed 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
of the coil. Heat treatment is performed at a specific temperature to flatten the surface of the photoresist layer
113
. Next, a second layer
114
of the thin-film coil is formed on the photoresist layer
113
. A photoresist layer
115
is then formed into a specific shape on the photoresist layer
113
and the second layer
114
of the coil. Heat treatment is performed at a specific temperature to flatten the surface of the photoresist layer
115
.
A top pole layer
116
for the recording head is formed 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 (NiFe). Next, an overcoat layer
117
of alumina, for example, is formed to cover the top pole layer
116
. Finally, machine processing of the slider including the forgoing layers is performed to form the air bearing surface
118
of the recording head and the reproducing head. The thin-film magnetic head element is thus completed.
In
FIG. 67
, the overcoat
Kamigama Takehiro
Sasaki Yoshitaka
Oliff & Berridg,e PLC
Tupper Robert S.
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