Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-08-22
2001-11-13
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192350, C216S066000, C216S022000
Reexamination Certificate
active
06315875
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a thin-film magnetic head having at least a magnetoresistive element for reading, 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. 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 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. 21
to
FIG. 26
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. This composite head incorporates a spin valve GMR element as a reproducing head.
FIG. 21
to
FIG. 24
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. 21
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, and 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 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 shield gap film
104
a
as an insulating layer made of an insulating material such as alumina is deposited to a thickness of 20 to 40 nm, for example, through sputtering. Next, a second shield gap film
104
b
as an insulating layer made of an insulating material such as alumina is deposited to a thickness of 50 to 150 nm, for example, through sputtering in a region on the first shield gap film
104
a
except where a GMR element described later is to be formed.
On the second shield gap film
104
b
a plurality of layers making up the GMR element for reproduction are formed. These layers are: an antiferromagnetic layer
105
a
having a thickness of about 10 to 20 nm; a nonmagnetic layer
105
b
having a thickness of about 2 to 3 nm; and a free layer (magnetic layer)
105
c
having a thickness of about 3 to 6 nm. These layers are formed in this order. In addition to these layers, layers such as a magnetic layer to be a pin layer may be required, if necessary, for making up the GMR element. However, the three layers
105
a
,
105
b
and
105
c
are only illustrated in the following description for simplification.
Next, on the free layer
105
c
a photoresist pattern
121
is selectively formed where the GMR element is to be formed. The photoresist pattern
121
is formed into a shape that facilitates lift-off, such as a shape having a T-shaped cross section.
Next, as shown in
FIG. 22
, with the photoresist pattern
121
as a mask, the above-mentioned layers
105
a
,
105
b
and
105
c
making up the GMR element are selectively etched through ion milling, for example, and patterned to form the GMR element
105
.
Next, as shown in
FIG. 23
, using the photoresist pattern
121
as a mask, a pair of conductive layers (that may be called leads)
106
whose thickness is tens to a hundred and tens of nanometers, for example, are formed into specific shapes on the first shield gap film
104
a
and the second shield gap film
104
b
. The conductive layers
106
are electrically connected to the GMR element
105
. Next, the photoresist pattern
121
is lifted off.
FIG. 25
is a top view illustrating the second shield gap film
104
b
, the GMR element
105
and the conductive layers
106
at this point in the manufacturing steps.
Next, as shown in
FIG. 24
, a third shield gap film
107
a
made of an insulating material such as alumina and having a thickness of 20 to 40 nm, for example, is formed through sputtering, for example, as an insulating layer 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 fourth shield gap film
107
b
made of an insulating material such as alumina and having a thickness of 50 to 150 nm, for example, is formed through sputtering, for example, as an insulating layer in a region on top of the third shield gap film
107
a
except the neighborhood of the GMR element
105
.
Next, 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
having a thickness of about 3&mgr;m is formed. The top shield layer
108
is made of a magnetic material and used for both a reproducing head and a recording head.
Next, on the top shield layer
108
, a recording gap layer
112
made of an insulating film such as an alumina film whose thickness is 0.2 to 0.3&mgr;m is formed. Although not shown, a contact hole is formed through selectively etching a portion of the recording gap layer
112
in a center portion of a region where a thin-film coil described later is formed.
Next, although not shown, on the recording gap layer
112
, a first photoresist layer for determining the throat height is formed into a specific shape 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 an end located in the air bearing surface (the medium facing surface that faces toward a recording medium) and the other end, the portions facing each other with the recording gap layer in between.
Next, on the first photoresist layer, the thin-film coil of the recording head is formed. The thickness of the coil is 3&mgr;m, for example. Next, a second photoresist layer for insulating the thin-film coil is formed into a specific shape on the first photoresist layer and the coil.
FIG. 26
is a top view illustrating the state at this point of the manufacturing steps in a simplified manner. In
FIG. 26
numeral
113
indicates the thin-film coil illustrated in a simplified manner. Numeral
131
indicates conductive layers formed on ends of the conductive layers
106
farther from the GMR element
105
. Numeral
132
indicates conductive layers connected to the conductive layers
131
. The conductive layers
131
may be made of a material the same as that of the top shield layer
108
and formed at the same time as the top shield layer
108
. The conductive layers
132
may be made of a material the same as that of the thin-film coil
113
and formed at the same time as the coil
113
.
Next, as shown in
FIG. 24
, a top pole layer
114
having a thickness of about 3&mgr;m is formed for the recording head on the recording gap layer
112
and the first and second photoresist layers. The top pole layer
114
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)
108
through the contact hole formed in the center portion of the region where the thin-film coil is formed.
Next, the recording gap layer
112
and a portion of the top shield layer (bottom pole layer)
108
are etched through ion milling, for example, using the top pole layer
114
Cantelmo Gregg
Nguyen Nam
Oliff & Berridg,e PLC
TDK Corporation
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