Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-08-05
2003-06-24
Whitehead, Jr., Carl (Department: 2813)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06583954
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 for writing and a method of manufacturing the thin-film magnetic head.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought with an increase in surface recording density of a hard disk drive. A composite thin-film magnetic head has been widely used which 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 AMR head or simply MR head. A reproducing head using a GMR element is called 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 gigabit per square inch.
Methods for improving the performance of a reproducing head include replacing an AMR film with a GMR film and the like having an excellent magnetoresistive sensitivity and optimizing the pattern width such as the MR height, in particular. The MR height is the length (height) between the air-bearing-surface-side end of an MR element 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 the surface of a thin-film magnetic head that faces a magnetic recording medium and may be called track surface as well.
Performance improvements in a recording head have been expected, too, with performance improvements in a reproducing head. One of the factors determining the recording head performance is the throat height (TH). The throat height is the length (height) of the pole portion between the air bearing surface and the end of the insulating layer electrically isolating the thin-film coil for generating magnetic flux. 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 the recording density among the performances of a recording head. In order to achieve this, it is required to implement a recording head of a narrow track structure wherein the width on the air bearing surface of a bottom pole and a top pole sandwiching a write gap is reduced to the order of some microns to submicron. Semiconductor process techniques are employed to achieve the narrow track structure.
Reference is now made to
FIG. 31A
to FIG.
37
A and
FIG. 31B
to FIG.
37
B to describe an example of a method of manufacturing a related-art composite thin-film magnetic head.
FIG. 31A
to
FIG. 37A
are cross sections each orthogonal to the air bearing surface.
FIG. 31B
to
FIG. 37B
are cross sections each parallel to the air bearing surface.
In the manufacturing method, as shown in FIG.
31
A and
FIG. 31B
, 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. On the insulating layer
102
a bottom shield layer
103
made of a magnetic material of 2 to 3 &mgr;m in thickness is formed for making a reproducing head.
Next, as shown in FIG.
32
A and
FIG. 32B
, on the bottom shield layer
103
alumina or aluminum nitride, for example, of 50 to 150 nm in thickness is deposited through sputtering to form a bottom shield gap film
104
as an insulating layer. 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, on the MR film a photoresist pattern is selectively formed where the MR element
105
is to be formed. The photoresist pattern takes 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 first electrode layers
106
having a thickness of tens of nanometers are formed, using the photoresist pattern as a mask. The first electrode layers
106
are electrically connected to the MR element
105
. The first electrode layers
106
may be formed through stacking TiW, CoPt, TiW, and Ta, for example. Next, the photoresist pattern is lifted off.
Next, as shown in
FIG. 33A and 33B
, a pair of second electrode layers
107
having a thickness of 150 nm, for example, are formed into a specific pattern. The second electrode layers
107
are electrically connected to the first electrode layers
106
. The second electrode layers
107
may be made of copper (Cu), for example. The first electrode layers
106
and the second electrode layers
107
make up leads electrically connected to the MR element
105
.
Next, as shown in FIG.
34
A and
FIG. 34B
, a top shield gap film
108
of 50 to 150 nm in thickness is formed as an insulating layer on the bottom shield gap film
104
and the MR film
105
. The MR film
105
is embedded in the shield gap films
104
and
108
. Next, on the top shield gap film
108
a top shield layer-cum-bottom pole layer (called bottom pole layer in the following description)
109
of about 3 &mgr;m in thickness is formed. The bottom pole layer
109
is made of a magnetic material and used for both a reproducing head and a recording head.
Next, as shown in FIG.
35
A and
FIG. 35B
, on the bottom pole layer
109
, a recording gap layer
110
made of an insulating film such as an alumina film whose thickness is about 0.2 to 0.3 &mgr;m is formed. On the recording gap layer
110
a photoresist layer
111
for determining the throat height is formed into a specific pattern whose thickness is about 1.0 to 2.0 &mgr;m. Next, on the photoresist layer
111
a thin-film coil
112
of a first layer is made for the induction-type recording head. The thickness of the thin-film coil
112
is 3 &mgr;m. Next, a photoresist layer
113
is formed into a specific pattern on the photoresist layer
111
and the coil
112
. Heat treatment is then performed at a temperature of 200 to 250° C., for example, 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 into a thickness of 3 &mgr;m. 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 at a temperature of 200 to 250° C., for example, to flatten the surface of the photoresist layer
115
.
Next, as shown in FIG.
36
A and
FIG. 36B
, a portion of the recording gap layer
110
behind the coils
112
and
114
(the right side of
FIG. 36A
) is etched to form a magnetic path. A top pole layer
116
having a thickness of about 3 &mgr;m is then formed for the recording head on the recording gap layer
110
and the photoresist layers
111
,
113
and
115
. The top pole layer
116
is made of a magnetic material such as Permalloy (NiFe) or FeN as a high saturation flux density material. The top pole layer
116
comes to contact with the bottom pole layer
109
and is magnetically coupled to the bottom pole layer
109
in a portion behind the coils
112
and
114
.
Next, as shown in FIG.
37
A and
FIG. 37B
, the recording gap layer
110
and the bottom pole layer
109
are etched through ion-milling, using the top pole layer
116
as a mask. Next, an overcoat layer
117
of alumina, for example, having a thickness of 20 to 30 &mgr;m is formed to cover the top pole layer
116
. Fin
Dolan Jennifer M
Jr. Carl Whitehead
Oliff & Berridg,e PLC
TDK Corporation
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