Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
2001-06-01
2004-01-06
Zarabian, Amir (Department: 2822)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
C438S712000, C438S720000, C438S734000, C360S319000, C360S313000, C360S317000, C360S125330
Reexamination Certificate
active
06673633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming a patterned thin film by etching a film to be patterned, and to a method of manufacturing a thin-film magnetic head, the method including the step of forming a magnetic layer by etching a film to be patterned.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought as areal 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 write (recording) head having an induction-type electromagnetic transducer for writing and a read (reproducing) head having a magnetoresistive (MR) element for reading.
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 write head. To achieve this, it is required to implement a write head of a narrow track structure wherein the width of top and bottom poles sandwiching the write gap layer on a side of the medium facing surface (air bearing surface) is reduced down to microns or the order of submicron. Semiconductor process techniques are utilized to implement such a structure.
A write track width of 0.2 to 0.3 &mgr;m has been recently required to implement a composite thin-film magnetic head that has an areal recording density of 40 to 60 gigabits per square inch.
In many of prior-art thin-film magnetic heads the magnetic layer that defines the write track width is made of NiFe and formed through plating. The saturation flux density of NiFe is increased by increasing the proportion of Fe. A well-known type of NiFe having a high saturation flux density is made up of 45 weight % of Ni and 55 weight % of Fe and exhibits a saturation flux density of about 1.6 T. If such a type of NiFe that has a high saturation flux density is utilized, the magnetic layer having a high saturation flux density is formed.
However, if the write track width is reduced as described above, it is impossible to obtain a sufficient magnetic flux in the air bearing surface even though the magnetic layer that defines the write track width is made of a type of NiFe that exhibits a high saturation flux density. As a result, it is likely that writing characteristics, such as an overwrite property that is a parameter indicating one of characteristics when data is written over existing data, are made insufficient.
To solve this problem, it is possible that the magnetic layer that defines the write track width is made of a high saturation flux density material, such as FeN or FeCo, that has a saturation flux density of about 2.0 T, for example, that is greater than the saturation flux density of NiFe. To form a patterned thin film made of such a high saturation flux density material, a method of etching a film to be patterned that is formed through sputtering is generally used. The etching method is ion milling, for example.
Reference is now made to
FIG. 10A
to FIG.
14
A and
FIG. 10B
to
FIG. 14B
to describe an example of a method of manufacturing a thin-film magnetic head, the method including the step of forming the magnetic layer that defines the write track width by etching a film to be patterned through ion milling as described above.
FIG. 10A
to
FIG. 14A
are cross sections each orthogonal to the air bearing surface of the thin-film magnetic head.
FIG. 10B
to
FIG. 14B
are cross sections of a pole portion of the head each parallel to the air bearing surface.
In the manufacturing method, as shown in FIG.
10
A and
FIG. 10B
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, 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 is formed for making a read head.
Next, on the bottom shield layer
103
, alumina, for example, 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 element
105
for reading is formed. Next, a pair of electrode layers
106
are formed on the bottom shield gap film
104
. The electrode layers
106
are electrically connected to the MR element
105
.
Next, a top shield gap film
107
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
107
.
Next, on the top shield gap film
107
, a top-shield-layer-cum-bottom-pole-layer (called a bottom pole layer in the following description)
108
having a thickness of about 3 &mgr;m is formed. The bottom pole layer
108
is made of a magnetic material and used for both a read head and a write head.
Next, as shown in FIG.
11
A and
FIG. 11B
, on the bottom pole layer
108
, a write gap layer
109
made of an insulating film such as an alumina film whose thickness is 0.15 &mgr;m is formed. Next, a portion of the write gap layer
109
is etched to form a contact hole
109
A to make a magnetic path.
Next, a high saturation flux density material such as FeN or FeCo is sputtered over the entire surface to form a film to be patterned having a thickness of about 1.0 to 2.0 &mgr;m. On this film to be patterned photoresist masks
112
a
and
112
b
made of patterned photoresist layers and having a thickness of about 5 &mgr;m, for example, are formed. The photoresist mask
112
a
is formed on a portion of the film to be patterned that will be a pole portion. The photoresist mask
112
b
is formed on a portion of the film to be patterned located above the contact hole
109
A.
Using the photoresist masks
112
a
and
112
b
as masks, the film to be patterned is etched through ion milling to form a pole portion layer
111
a
and a magnetic layer
111
b
. The pole portion layer
111
a
makes up the pole portion of the top pole layer. The magnetic layer
111
b
is connected to the bottom pole layer
108
. The pole portion layer
111
a
has a width equal to the write track width.
Next, as shown in FIG.
12
A and
FIG. 12B
, the photoresist masks
112
a
and
112
b
are removed. Next, a portion of the write gap layer
109
around the pole portion layer
111
a
is etched, using the pole portion layer
111
a
as a mask. Furthermore, the bottom pole layer
108
is etched by 0.3 &mgr;m only, for example. As shown in
FIG. 12B
, the structure thereby obtained is called a trim structure wherein the sidewalls of the pole portion layer
111
a
, the write gap layer
109
, and a part of the bottom pole layer
108
are formed vertically in a self-aligned manner.
Next, an insulating layer
113
made of an alumina film, for example, and having a thickness of 2 to 3 &mgr;m is formed on the entire surface. The insulating layer
113
is then polished to the surfaces of the pole portion layer
111
a
and the magnetic layer
111
b
and flattened.
Next, on the flattened insulating layer
113
, a first layer
114
of a thin-film coil made of copper (Cu), for example, and having a thickness of 1 to 2 &mgr;m is formed for the induction-type write head. In
FIG. 12A
numeral
114
a
indicates a portion of the first layer
114
that will be connected to a second layer
116
of the coil described later. Next, a photoresist layer
115
having a specific shape is formed on the insulating layer
113
and the first layer
114
. Heat treatment is performed at a specific temperature to flatten the surface of the photoresist layer
115
.
Next, as shown in FIG.
13
A and
FIG. 13B
, on the photoresist layer
115
, the second layer
116
of the thin-film coil having a thickness of 1 to 2 &mgr;m is formed. Next, a photoresist layer
117
having a specific shape is formed on the photoresist layer
115
and the second layer
116
. Heat treatment is performed at a specific temperature to flatten the surface of the photoresist layer
117
.
Next, a yoke portion layer
118
made of a magnetic material and having
Novacek Christy
Oliff & Berridg,e PLC
TDK Corporation
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