Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-02-28
2004-05-18
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C029S603140
Reexamination Certificate
active
06738232
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composite thin-film magnetic head comprising a recording head and a reproducing head and a method of manufacturing such a thin-film magnetic head, and to a thin-film magnetic head material used for producing such a thin-film magnetic head and a method of manufacturing such a thin-film magnetic head material.
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 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. 38A
to
FIG. 46A
,
FIG. 38B
to
FIG. 46B
, and
FIG. 47
to
FIG. 49
to describe an example of a manufacturing method of a composite thin-film magnetic head as an example of a manufacturing method of a related-art thin-film magnetic head.
FIG. 38A
to
FIG. 46A
are cross sections each orthogonal to the air bearing surface.
FIG. 38B
to
FIG. 46B
are cross sections each parallel to the air bearing surface of the pole portion.
According to the manufacturing method, as shown in FIG.
38
A and
FIG. 38B
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, having a thickness of about 5 &mgr;m, is deposited on a substrate
101
made of aluminum oxide and titanium carbide (Al
2
O
3
—TiC), for example.
Next, as shown in FIG.
39
A and
FIG. 39B
, on the insulating layer
102
, a bottom shield layer
103
made of a magnetic material is formed for a reproducing head.
Next, as shown in FIG.
40
A and
FIG. 40B
, on the bottom shield layer
103
, alumina, for example, having a thickness of 40 to 70 nm, is deposited through sputtering to form a bottom shield gap film
104
as an insulating film. On the bottom shield gap film
104
, an MR film of tens of nanometers in thickness is formed for making an MR element
105
for reproduction. Next, with a 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, as shown in FIG.
41
A and
FIG. 41B
, a top shield gap film
106
as an insulating layer is formed 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
106
.
Next, as shown in FIG.
42
A and
FIG. 42B
, on the top shield gap film
106
, a top shield layer-cum-bottom pole layer (called a top shield layer in the following description)
107
is formed. The top shield layer
107
is made of a magnetic material and used for both a reproducing head and a recording head.
Next, a recording gap layer
108
made of an insulating film such as an alumina film is formed on the top shield layer
107
. Next, the recording gap layer
108
is partially etched in a backward portion (the right side of
FIG. 42A
) to form a contact hole for making a magnetic path. Next, a top pole tip
109
for the recording head is formed on the pole portion of the recording gap layer
108
. The top pole tip
109
is made of a magnetic material such as Permalloy (NiFe) or FeN
x
as a high saturation flux density material. The top pole tip
109
forms part of a top pole layer. 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
108
and the top shield layer (bottom pole layer)
107
are etched through ion milling, using the top pole tip
109
as a mask. As shown in
FIG. 42B
, the structure is called a trim structure wherein the sidewalls of the top pole layer (the top pole tip
109
), the recording gap layer
108
, and part of the top shield layer (bottom pole layer)
107
are formed vertically in a self-aligned manner. The trim structure suppresses an increase in the effective track width due to expansion of the magnetic flux generated during writing in a narrow track.
Next, as shown in FIG.
43
A and
FIG. 43B
, an insulating layer
110
of alumina, for example, having a thickness of about 3 &mgr;m is formed over the entire surface. The insulating layer
110
is polished to the surfaces of the top pole tip
109
and the magnetic layer
119
and flattened. The polishing method may be mechanical polishing or chemical mechanical polishing (CMP). The surfaces of the top pole tip
109
and the magnetic layer
119
are thereby exposed.
On the flattened insulating layer
110
a photoresist layer
111
is formed into a specific pattern through high-precision photolithography. Next, on the photoresist layer
111
a thin-film coil
112
of a first layer is made for the induction-type recording head. The thin-film coil
112
is made of copper (Cu), for example.
Next, as shown in FIG.
44
A and
FIG. 44B
, a photoresist layer
113
is formed into a specific pattern on the photoresist layer
111
and the coil
112
. Heat treatment is performed at a temperature of 250 to 300° C., for example, to flatten the surface of the photoresist layer
113
.
Next, as shown in FIG.
45
A and
FIG. 45B
, a thin-film coil
114
of a second layer is formed on the photoresist layer
113
. Next, a photoresist layer
115
is formed into a specific pattern on the photoresist layer
113
and the coil
114
. Heat treatment is performed at a temperature of 250 to 300° C., for example, to flatten the surface of the photoresist layer
115
.
Next, as shown in FIG.
46
Castro Angel
Heinz A. J.
Oliff & Berridg,e PLC
TDK Corporation
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