Etching a substrate: processes – Planarizing a nonplanar surface
Reexamination Certificate
1999-11-09
2002-05-14
Stinson, Frankie L. (Department: 1746)
Etching a substrate: processes
Planarizing a nonplanar surface
C216S018000, C216S022000, C216S053000, C360S313000, C360S319000, C360S320000
Reexamination Certificate
active
06387285
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.
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 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.
Methods for improving the performance of a reproducing head include replacing an AMR film with a GMR film and the like made of a material or a configuration having an excellent magnetoresistive sensitivity, or optimizing the MR height of the MR film. 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 a track surface as well.
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. 22A
to
FIG. 29A
,
FIG. 22B
to
FIG. 29B
, FIG.
31
and
FIG. 32
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. 22A
to
FIG. 29A
are cross sections each orthogonal to the air bearing surface of the head.
FIG. 22B
to
FIG. 29B
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
FIGS. 22A and 29B
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, of about 5 to 10 &mgr;m in thickness 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, as shown in
FIGS. 23A and 23B
, on the bottom shield layer
103
, alumina or aluminum nitride, for example, is deposited to a thickness of 50 to 100 nm through sputtering to form a bottom shield gap film
104
as an insulating layer. On the bottom shield gap film
104
, 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 easily allows 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
FIGS. 24A and 24B
, on the bottom shield gap film
104
, a pair of first electrode layers
107
whose thickness is tens of nanometers are formed, using the photoresist pattern
106
as a mask. The first electrode layers
107
are electrically connected to the MR element
105
. The first electrode layers
107
may be formed through stacking TiW, CoPt, TiW, and Ta, for example. Next, as shown in
FIGS. 25A and 25B
, the photoresist pattern
106
is lifted off. Although not shown in
FIGS. 25A and 25B
, a pair of second electrode layers whose thickness is 50 to 100 nm are formed into a specific pattern. The second electrode layers are electrically connected to the first electrode layers
107
. The second electrode layers may be made of copper (Cu), for example. The first electrode layers
107
and the second electrode layers make up an electrode (that may be called a lead as well) electrically connected to the MR element
105
.
Next, as shown in FIG.
26
A and
FIG. 26B
, a top shield gap film
108
having a thickness of 50 to 150 nm is formed as an insulating layer 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
108
. Next, on the top shield gap film
108
, a top shield layer-cum-bottom pole (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.
Next, as shown in FIG.
27
A and
FIG. 27B
, on the top shield layer
109
, a recording gap layer
110
made of an insulating film such as an alumina film whose thickness is 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
. 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
.
Next, as shown in FIG.
28
A and
FIG. 28B
, the recording gap layer
110
is partially etched in a portion behind the coils
112
and
114
(the right side of
FIG. 28A
) to form a magnetic path. A top pole
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
116
is made of a magnetic material such as Permalloy (NiFe) or FeN as a high saturation flux density material. The top pole
116
is in contact with the top shield layer (bottom pole)
109
and is magnetically coupled to the top shield layer
109
in a portion behind the coils
112
and
114
.
As shown in FIG.
29
A and
FIG.29B
, the recording gap layer
110
and the top shield layer (bottom pole)
109
are etched through ion milling, using the top pole
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
116
. Finally, machine processing of the slider is performed to form the air bearing surfaces of the recording head and the reproducing head. The thin-film magnetic head is thus completed. As shown in FIG.
29
A and
FIG. 29B
, the structure is called a trim structure wherein the sidewalls of the top pole
116
, the recording gap layer
110
, and part of the top shield layer (bottom pole)
109
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.
FIG. 30
is a top view wherein the MR element
105
, the first electrode layers
107
and the second electrode layers
118
are formed on the bottom shield gap film
104
.
FIG. 31
is a top view of the thin-film magnetic head manufactured as described above. The overcoat layer
117
is omitted in FIG.
31
.
FIG. 22A
to
FIG. 29A
are cross sections taken along line
29
A—
29
A of FIG.
31
.
FIG. 22B
to
FIG. 29B
Smetana Jiri
TDK Corporation
LandOfFree
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