Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-03-31
2002-05-21
Cao, Allen (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06392852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head having at least a magnetoresistive element for reading and a method of manufacturing such a thin-film magnetic head, and to a magnetoresistive device having a magnetoresistive element.
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.
Many of reproducing heads have a structure in which the MR element is electrically and magnetically shielded by a magnetic material.
Reference is now made to
FIG. 14A
to FIG.
19
A and
FIG. 14B
to
FIG. 19B
to describe an example of a manufacturing method of a composite thin-film magnetic head as an example of a related-art manufacturing method of a thin-film magnetic head.
FIG. 1
to
FIG. 19A
are cross sections each orthogonal to the air bearing surface of the head.
FIG. 14B
to
FIG. 19B
are cross sections each parallel to the air bearing surface of the pole portion of the head.
According to the manufacturing method, as shown in FIG.
14
A and
FIG. 14B
, 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 and having a thickness of 2 to 3 &mgr;m is formed for a reproducing head.
Next, on the bottom shield layer
103
, a first bottom shield gap film
104
a
as an insulating layer made of alumina, for example, is deposited to a thickness of 40 to 70 nm, for example. On the first bottom shield gap film
104
a,
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
106
is selectively formed where the MR element
105
is to be formed. The photoresist pattern
106
is formed into a shape that facilitates lift-off, such as a shape having a T-shaped cross section. Next, with the photoresist pattern
106
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.
15
A and
FIG. 15B
, a second bottom shield gap film
104
b
as an insulating layer is formed in a region on top of the first bottom shield gap film
104
a
except the neighborhood of the MR element
105
. The second bottom shield gap film
104
b
is made of alumina, for example, and has a thickness of 100 to 200 nm, for example. Next, using the photoresist pattern
106
as a mask, a pair of first conductive layers (that may be called leads)
107
whose thickness is 50 to 100 nm, for example, are formed into specific patterns on the first bottom shield gap film
104
a
and the second bottom shield gap film
104
b.
The first conductive layers
107
are electrically connected to the MR element
105
and may be made of copper (Cu), for example.
Next, as shown in FIG.
16
A and
FIG. 16B
, the photoresist pattern
106
is lifted off. Next, a first top shield gap film
108
a
made of alumina, for example, and having a thickness of 40 to 70 nm, for example, is formed as an insulating layer on the bottom shield gap films
104
a
and
104
b,
the MR element
105
and the first conductive layers
107
. The MR element
105
is embedded in the shield gap films
104
a
and
108
a.
Next, a second top shield gap film
108
b
as an insulating layer is formed in a region on top of the first top shield gap film
108
a
except the neighborhood of the MR element
105
. The second top shield gap film
108
b
is made of alumina, for example, and has a thickness of 100 to 200 nm, for example.
Next, as shown in FIG.
17
A and
FIG. 17B
, contact holes
130
are formed through selectively etching portions of the top shield gap films
108
a
and
108
b
located on top of an end of each of the first conductive layers
107
opposite to the MR element
105
(that is, on the right side of FIG.
17
A). The first conductive layers
107
are thus exposed.
Next, as shown in FIG.
18
A and
FIG. 18B
, on the top shield gap films
108
a
and
108
b,
a top-shield-layer-cum-bottom-pole-layer (called a top shield layer in the following description)
109
having a thickness of about 3 &mgr;m is formed. The top shield layer
109
is made of a magnetic material and used for both a reproducing head and a recording head. At the same time, a pair of second conductive layers
110
having a thickness of about 3 &mgr;m are formed on the bottoms of the contact holes
130
(FIG.
17
A). The second conductive layers
110
are made of the same material as the top shield layer
109
and electrically connected to the first conductive layers
107
. Next, an insulating layer
112
made of alumina, for example, and having a thickness of 4 to 6 &mgr;m, for example, is formed over the entire surface. The insulating layer
112
is flattened through chemical mechanical polishing (CMP), for example, until the top shield layer
109
and the second conductive layers
110
are exposed, and the surface is flattened.
Next, as shown in FIG.
19
A and
FIG. 19B
, on the top shield layer
109
, a recording gap layer
113
made of an insulating film such as an alumina film whose thickness is 0.2 to 0.3 &mgr;m is formed. Contact holes are formed through selectively etching a portion of the recording gap layer
113
in a center region where a thin-film coil described later is formed and portions on top of the second conductive layers
110
. Next, third conductive layers
114
connected to the second conductive layers
110
are formed in the contact holes provided on top of the second conductive layers
110
.
Next, on the recording gap layer
113
, a photoresist layer
115
for determining the throat height is formed into a specific pattern whose thickness is about 1.0 to 2.0 &mgr;m. The throat height is the length (height) of portions of the two magnetic layers of the recording head between the air-bearing-surface-side end and the other end, the portions facing each other with the recording gap layer in between.
Next, on the photoresist layer
115
, the thin-film coil
116
of the recording head is formed. The thickness of the coil
116
is 3 &mgr;m, for example. Next, a photoresist layer
117
is formed into a specific pattern on the photoresist layer
115
, the coil
116
and the third conductive layers
114
.
Next, a top pole layer
118
having a thickness of about 3 &mgr;m is formed for the recording head on the recording gap layer
113
and the photoresist layers
115
and
117
. The top pole layer
118
is made of a magnetic material such as Permalloy (NiFe) and is in contact with and magnetically coupled to the top shield layer (bottom pole layer)
109
through the contact hole formed in the center portion of the region where the thin-film coil
116
is formed.
Next, the recording gap layer
113
and the top shield layer (bottom pole layer)
109
are etched through ion milling, for example, using the top pole layer
118
as a mask. As shown in
FIG. 19B
, the structure is called a trim structure wherein the sidewalls of the top pole layer
118
, the re
Cao Allen
Oliff & Berridg,e PLC
TDK Corporation
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