Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-10-12
2002-01-29
Ometz, David L. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S320000
Reexamination Certificate
active
06342993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a thin film magnetic head having at least a magnetoresistive element for reading out and a method of manufacturing the same.
2. Description of the Related Art
In recent years, performance improvement in thin film magnetic heads has been sought in accordance with an increase in surface recording density of a hard disk drive. As a thin film magnetic head, a composite thin film magnetic head has been widely used. A composite thin film magnetic head has a layered structure which includes a recording head with an inductive-type magnetic transducer for writing and a reproducing head with a magnetoresistive element (also referred as MR element in the followings) for reading-out. There are a few types of MR elements: one is an AMR element that utilizes the anisotropic magnetoresistance effect (referred as AMR effect in the followings) and the other is a GMR element that utilizes the giant magnetoresistance effect (referred as GMR effect in the followings). A reproducing head using an AMR element is called an AMR head or simply an MR head. A reproducing head using the GMR element is called a GMR head. The AMR head is used as a reproducing head whose surface recording density is more than 1 gigabit per square inch. The GMR head is used as a reproducing head whose surface recording density is more than 3 gigabit per square inch.
The AMR head includes an AMR film having the AMR effect. The GMR head has the similar configuration to the AMR head except that the AMR film is replaced with a GMR film having the GMR effect. However, compared to the AMR film, the GMR film exhibits a greater change in resistance under a specific external magnetic field. Accordingly, the reproducing output of the GMR head becomes about three to five times greater than that of the AMR head.
In general, an AMR element is a film made of a magnetic substance which exhibits the MR effect and has a structure of two to four layers. In contrast, most of the GMR films have a multi-layered structure consisting of a plurality of films. There are several types of mechanisms which produce the GMR effect. The layer structure of the GMR film depends on those mechanisms. GMR films include a superlattice GMR film, a granular film, a spin valve film and so on. The spin valve film is most sufficient since the film has a relatively simple structure, exhibits a great change in resistance in a low magnetic field, and is suitable for mass production. The performance of the reproducing head can be easily improved by, for example, replacing an AMR film with an MR film with high magnetoresistive sensitivity such as a GMR film.
Now, an example of a method of manufacturing a composite thin film magnetic head (AMR head) will be described with reference to
FIG. 12
to
FIGS. 19A
,
19
B as an example of a method of manufacturing a thin film magnetic head of the related art.
FIG. 12
to
FIG. 16
show an enlarged configuration of the air bearing surface (ABS) of the AMR head, respectively.
FIG. 17A
to
FIG. 19A
show the cross sectional configuration of the AMR head vertical to the air bearing surface while
FIG.17B
to
FIG. 19B
show the cross sectional configuration of the pole portion parallel to the air bearing surface, respectively.
First, as shown in
FIG. 12
, an insulating layer
102
made of, for example, alumina (Al
2
O
3
) is deposited to a thickness of about 5 to 10 &mgr;m on a substrate
101
made of, for example, attic (Al
2
O
3
—TiC). Next, a bottom shield layer
103
for a reproducing head made of a magnetic material is formed in a thickness of about 2 to 3 &mgr;m on the insulating layer
102
. Next, a bottom shield gap film
105
as an insulating layer is formed through depositing, for example, alumina or aluminum nitride in thickness of 50 to 100 nm on the bottom shield layer
103
by sputtering. Next, a SAL (Soft Adjacent Layer) film
106
a
for applying bias magnetic field, a tantalum (Ta) film
106
b
as a magnetic isolation film and an AMR film
106
c
are formed on the bottom shield gap film
105
in this order.
Next, as shown in
FIG. 13
, a photoresist pattern
107
having a longitudinal bar
107
a
and a lateral bar
107
b
is selectively formed on the AMR film
106
c
. At this time, a photoresist pattern
107
with, for example, a T-shaped cross section is formed so that lift-off can be easily performed. Next, an AMR element
106
is formed through etching the AMR film
106
c
, the tantalum film
106
b
and the SAL film
106
a
to a taper shape by, for example, ion milling using the photoresist pattern
107
as a mask.
Next, as shown in
FIG. 14
, a pair of lead electrode layers
108
which are electrically connected to the AMR film
106
c
are formed on the shield gap film
105
by, for example, sputtering using the photoresist pattern
107
as a mask. The lead electrode layers
108
have a configuration in which a domain control film for suppressing noise made of, for example, cobalt-platinum alloy (CoPt) and a lead film for detecting signals made of, for example, titanium-tungsten (TiW) or tantalum are stacked, and are formed to cover the adjacent area of the end (side-end face and both end of the surface) of the AMR film
106
c.
Next, as shown in
FIG. 15
, the photoresist pattern
107
is lifted off. Then, although not shown in
FIG. 15
, another pair of lead electrode layers
111
(See.
FIG. 17B
) which are electrically connected to the lead electrode layers
108
are formed in a thickness of about 100 to 300 nm in a predetermined pattern. The lead electrode layers
111
are not exposed to the air bearing surface (ABS). Therefore, they are formed of a substance with low resistivity such as copper (Cu).
Next, as shown in
FIG. 16
, a top shield gap film
109
as an insulating layer is formed in a thickness of 50 to 150 nm on the lead electrode layers
108
and the AMR film
106
c
so as to bury the AMR element
106
in the shield gap films
105
and
109
. Next, a top shield layer-cum-bottom pole (referred as a top shield layer in the followings)
110
made of a magnetic material, which is used for both a reproducing head and a recording head, is formed in a thickness of about 3 &mgr;m on the top shield gap film
109
.
Next, as shown in
FIGS. 17A and 17B
, a write gap layer
112
made of an insulating film such as an alumina film is formed in a thickness of 0.2 to 0.3 &mgr;m on the top shield layer
110
. Then, an opening (contact hole)
112
a
for a magnetic path is formed by partially etching the write gap layer
112
in a backward position (right-side in
FIGS. 17A and 17B
) of a region where thin film coils
114
and
115
are to be formed later. Next, a photoresist layer
113
a
for determining the throat height is formed in a thickness of about 1.0 to 2.0 &mgr;m in a predetermined pattern on the write gap layer
112
. Then, a thin film coil
114
for an inductive-type recording head is formed in a thickness of 3 &mgr;m on the photoresist layer
113
a
. Next, a photoresist layer
113
b
is formed in a predetermined pattern on the photoresist layer
113
a
and the thin film coil
114
. Next, a thin film coil
115
is formed in a thickness of 3 &mgr;m on the photoresist layer
113
b
. Then, a photoresist layer
113
c
is formed in a predetermined pattern on the photoresist layer
113
b
and the thin film coil
115
.
Next, as shown in
FIGS. 18A and 18B
, a top pole
116
made of magnetic materials for a recording head such as permalloy (NiFe) or nitride ferrous (FeN) is formed in a thickness of about 30 &mgr;m on the write gap layer
112
and the photoresist layers
113
a
to
113
c
. The top pole
116
is in contact with and magnetically coupled to the top shield layer
110
through the contact hole
112
a
in the backward position of the thin film coils
114
and
115
.
Next, as shown in
FIGS. 19A and 19B
, the write gap layer
112
and the top shield layer
110
are etched by ion milling using the top pole
116
as a mask. Next, an overcoat layer
117
made of, for example, alumina is formed in a thickness of 20 to 50 &
Ometz David L.
TDK Corporation
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