Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-06-23
2001-09-04
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06285532
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 magnetic head, and to a thin-film magnetic head material used for producing a composite thin-film magnetic head having a magnetoresistive element and an induction-type magnetic transducer and a method of manufacturing such a thin-film magnetic head material.
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 AMR head or simply MR head. A reproducing head using a GMR element is called 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.
An AMR head comprises an AMR film having the AMR effect. In place of the AMR film a GMR head comprises a GMR film having the GMR effect. The configuration of the GMR head is similar to that of the AMR head. However, the GMR film exhibits a greater change in resistance under a specific external magnetic field compared to the AMR film. As a result, the reproducing output of the GMR head is about three to five times as great as that of the AMR head.
The MR film may be changed in order to improve the performance of a reproducing head. In general, an AMR film is made of a magnetic substance that exhibits the MR effect and has a single-layer structure. In contrast, many of GMR films have a multilayer structure consisting of a plurality of films. There are several types of mechanisms of producing the GMR effect. The layer structure of a GMR film depends on the mechanism. GMR films include a superlattice GMR film, a granular film, a spin valve film and so on. The spin valve film is most efficient since the film has a relatively simple structure, exhibits a great change in resistance in a low magnetic field, and suitable for mass production. The performance of the reproducing head is thus easily improved by replacing the AMR film with a GMR film and the like with an excellent magnetoresistive sensitivity.
Besides selection of a material as described above, the pattern width such as the MR height, in particular, determines the performance of a reproducing head. The MR height is the length (height) between the end of the MR element closer to the air bearing surface (medium facing surface) and the other end. The MR height is basically controlled by an amount of lapping when the air bearing surface is processed.
Many of reproducing heads have a structure in which the MR element is electrically and magnetically shielded by a magnetic material.
Referring to
FIG. 91
to
FIG. 100
, an example of a manufacturing method of a composite thin-film magnetic head will now be described as an example of a manufacturing method of a related-art thin-film magnetic head.
FIGS. 91A
to
FIG. 98A
are cross sections orthogonal to the air bearing surface.
FIGS. 91B
to
FIG. 98B
are cross sections parallel to the air bearing surface of the pole portion.
According to the manufacturing method, as shown in
FIGS. 91A and 91B
, an insulating layer
1102
made of alumina (Al
2
O
3
), for example, of about 5 to 10 &mgr;m in thickness is deposited on a substrate
1101
made of aluminum oxide and titanium carbide (Al
2
O
3
-TiC), for example. On the insulating layer
1102
a bottom shield layer
1103
made of a magnetic material of 2 to 3 &mgr;m in thickness is formed for a reproducing head.
Next, as shown in
FIGS. 92A and 92B
, on the bottom shield layer
1103
alumina or aluminum nitride, for example, of 50 to 100 nm in thickness is deposited through sputtering to form a bottom shield gap film
1104
as an insulating layer. On the bottom shield gap film
1104
an MR film of tens of nanometers in thickness is formed for making an MR element
1105
for reproduction. Next, on the MR film a photoresist pattern
1106
is selectively formed where the MR element
1105
is to be formed. The photoresist pattern
1106
takes a shape that easily allows lift-off, such as a shape having a T-shaped cross section. Next, with the photoresist pattern
1106
as a mask, the MR film is etched through ion milling to form the MR element
1105
. The MR element
1105
may be either a GMR element or an AMR element.
Next, as shown in
FIGS. 93A and 93B
, on the bottom shield gap film
1104
a pair of first conductive layers
1107
whose thickness is tens of nanometers are formed, using the photoresist pattern
1106
as a mask. The first conductive layers
1107
are electrically connected to the MR element
1105
. The first conductive layers
1107
may have a multilayer structure including TiW, CoPt, TiW, and Ta, for example. Next, as shown in
FIGS. 94A and 94B
, the photoresist pattern
1106
is lifted off. Although not shown in
FIGS. 94A and 94B
, a pair of second conductive layers whose thickness is 50 to 100 nm are formed in a specific pattern. The second conductive layers are electrically connected to the first conductive layers
1107
. The second conductive layers may be made of copper (Cu), for example. The first conductive layers
1107
and the second conductive layers make up leads electrically connected to the MR element
1105
.
Next, as shown in FIG.
95
A and
FIG. 95B
, a top shield gap film
1108
of 50 to 150 nm in thickness is formed as an insulating layer on the bottom shield gap film
1104
and the MR film
1105
. The MR film
1105
is embedded in the shield gap films
1104
and
1108
. Next, on the top shield gap film
1108
a top shield layer-cum-bottom magnetic layer (called top shield layer in the following description)
1109
of about 3 &mgr;m in thickness is formed. The top shield layer
1109
is made of a magnetic material and used for both a reproducing head and a recording head.
Next, as shown in FIG.
96
A and
FIG. 96B
, on the top shield layer
1109
, a recording gap layer
1110
made of an insulating film such as an alumina film is formed whose thickness is about 0.2 to 0.3 &mgr;m. On the recording gap layer
1110
a photoresist layer
1111
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
1111
a thin-film coil
1112
of a first layer is made for the induction-type recording head. The thickness of the thin-film coil
1112
is 3 &mgr;m. Next, a photoresist layer
1113
is formed into a specific pattern on the photoresist layer
1111
and the coil
1112
. On the photoresist layer
1113
a thin-film coil
1114
of a second layer is then formed into a thickness of 3 &mgr;m. Next, a photoresist layer
1115
is formed into a specific pattern on the photoresist layer
1113
and the coil
1114
.
Next, as shown in FIG.
97
A and
FIG. 97B
, the recording gap layer
1110
is partially etched in a portion behind the coils
1112
and
1114
(the right side of
FIG. 97A
) to form a magnetic path. A top pole layer
1116
of about 3 &mgr;m in thickness is then formed on the recording gap layer
1110
and the photoresist layers
1111
,
1113
and
1115
. The top pole layer
1116
is made of a magnetic material for the recording head such as Permalloy (NiFe) or FeN as a high saturation flux density material. The top pole layer
1116
comes to contact with the top shield layer (bottom pole layer)
1109
and is magnetically coupled to the top shield layer
1109
in a portion behind the coils
1112
and
1114
.
As shown in FIG.
98
A and
Oliff & Berridg,e PLC
TDK Corporation
Tupper Robert S.
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