Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-09-29
2002-10-08
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S320000
Reexamination Certificate
active
06462915
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a thin film magnetic head having at least a reading magnetoresistive effective type thin film magnetic head and a method of manufacturing the same, particular a composite type thin film magnetic head in which a reading magnetoresistive effective type thin film magnetic head and a writing inductive type thin film magnetic head are stacked and supported by a substrate and a method of manufacturing the same.
2. Related Art Statement
Recently, with the development of surface recording density in hard disk devices, composite type thin film magnetic heads are required to have excellent characteristics.
Then, a composite type thin film magnetic head in which an inductive type thin film magnetic head for writing and a magnetoresistive effective type thin film magnetic head for reading is suggested and practically used. Although as the reading magnetoresistive element, a magnetoresistive effective type thin film magnetic head using a normal anisotropic magnetoresistive (AMR) effect has been generally employed, magnetoresistive effective type thin film magnetic heads using a giant magnetoresistive (GMR) effect able to obtain larger resistance variation ratio than the AMR element and three to five times as large output as the AMR element and a tunneling junction magnetoresistive (TMR) effect are developed.
In this specification, these AMR element, GMR element and TMR element are generically called as a “magnetoresistive effective type thin film magnetic head” or a “MR reproducing element” in brief.
The use of the AMR element enables a surface recording density of several giga bits/inch
2
to be realized, and the use of the GMR element or the TMR element enables the surface recording density to be more enhanced. Such a high surface recording density can realize a hard disk having a large capacity of more than 10G bites.
Generally, a MR film is composed of a film made of magnetic material showing the magenetoresistive effect and has a single layered structure. On the contrary, the GMR film mainly has a multi-layered structure composed of some films. There are some kinds of mechanism to generate the GMR effect, and the GMR film has a different structure depending on the mechanism. Concretely, as the GMR film, a superlattice GMR film, a granular film and a spin-valve film are exemplified. Particular, the spin-valve film has a relatively simple structure, suitable for mass-production, and shows a large resistance variation by a weak magnetic field.
In this way, the reading magnetoresistive effective type thin film magnetic head capable of attaining a high surface recording density can be easily realized by using the GMR film instead of the AMR film. On the other hand, with the characteristics of the reproducing head being enhanced, the characteristics of the writing head is required to be developed. The development of the surface recording density requires an enhancement of a track density in a magnetic recording medium. Thus, a width of a write gap in an ABS has to be narrowed to a submicron order from a several micron order, and for realizing it, a semiconductor processing technique is employed.
FIGS. 1-8
shows successive manufacturing steps of a conventional normal composite type thin film magnetic head. In each figures, reference “A” depicts a cross sectional view of the thin film magnetic head perpendicular to an ABS, and reference “B” depicts a cross sectional view of the magnetic pole portion parallel to the ABS. The composite type thin film magnetic head in this embodiment has a reading GMR reproducing element on a substrate and a writing inductive type thin film magnetic head stacked on the reading element. Since in practically manufacturing a thin film magnetic head, many thin film magnetic heads are formed on a wafer at the same time, the end of each thin film magnetic head does not appear. However, in the above figures, the end of the thin film magnetic head is shown for clarifying the figures.
First of all, as shown in
FIG. 1
, an insulating layer
2
made of alumina (Al
2
O
3
) is formed in a thickness of about 5-10 &mgr;m on a substrate
1
made of AlTiC, for example, on which a first magnetic layer
3
constituting one magnetic shield layer to protect the reading GMR element from an external magnetic field is formed in a thickness of 2-3 &mgr;m.
Then, as shown in
FIG. 2
, a first shield gap layer
4
is sputterformed, of alumina, in a thickness of about 50-100 &mgr;m, and thereafter a multilayered structure-magnetoresistive layer
5
constituting the GMR reproducing element is formed in a thickness of less than 10 &mgr;m. Moreover, for forming the magnetoresistive layer
5
into a desired pattern, a photoresist layer
6
is formed on the layer
5
. In this case, the photoresist layer
5
is formed to a shape for itself to be easily lifted off, for example, T-shape. Next, the magnetoresistive layer
5
is ion-milled through the photoresist film
6
as a mask, and thereby is formed in a desired pattern.
Then, as shown in
FIG. 3
, a first and a second conductive layers
7
a
,
7
b
are formed in a thickness of several ten nm by using the photoresist film
6
as a mask. The conductive layers
7
a
,
7
b
are composed of TiW/CoPt/TiW/Ta laminated body. Next, as shown in
FIGS. 4 and 5
, the photoresist film
6
is removed by a lift-off process. As shown in
FIGS. 4B and 5
, the one ends of the first and second conductive layers
7
a
,
7
b
are connected to the one ends of the magnetoresistive layer
5
, respectively. Moreover, as shown in
FIG. 5
, the cross section in
FIG. 4A
is taken on the plane slightly approaching to the first conductive layer
7
a
, not the plane passing through the center of the magnetoresistive layer
5
and perpendicular to the ABS.
Subsequently, as shown in
FIG. 6
, renewedly, a second shield gap film
8
made of alumina is formed in a thickness of 50-150 nm to embed the magnetoresistive layer
5
into the first and second shield gap layers
4
,
8
, and a second magnetic layer
9
made of permalloy is formed in a thickness of 2-3 &mgr;m. The second magnetic layer
9
work not only as the other shield to magnetically shield the GMR reproducing element with the above first magnetic layer
3
, but also as one pole in the writing thin film magnetic head.
Then, as shown in
FIG. 7
, a write gap layer
10
made of nonmagnetic material, for example, alumina, is formed in a thickness of about 200-300 nm on the second magnetic layer
9
and thereafter an insulating layer
11
made of photoresist is formed, on the part for a thin coil to be formed, in a thickness of 1-2 &mgr;m corresponding to a given pattern, on which a first layer-thin film coil
12
is formed in a thickness of 3 &mgr;m, insulation-separated by the photoresist film
13
. Moreover, the insulating layer
13
made of photoresist to cover the first layer-thin film coil
12
is flattened by thermal treatment, and thereafter a second layer-thin film coil
14
is formed in a thickness of 3 &mgr;m so as to be insulation-separated and supported by an insulating layer
15
made of photoresist.
Then, the insulating layer
15
made of photoresist to cover the second layer-thin film coil
14
is flattened by thermal treatment, and thereafter as shown in
FIG. 8
, a third magnetic layer
16
is formed corresponding to a given pattern. Then, as shown in
FIG. 9
, an overcoat layer
17
is formed in a thickness of 20-30 &mgr;m. The third magnetic layer
16
is made of a permalloy material or FeN material having a high saturated magnetic flux density.
Lastly, the side surfaces of the magnetoresistive layer
5
and the write gap layer
10
are polished to form an air bearing surface (ABS)
18
opposing to a magnetic recording medium. A GMR reproducing element
19
is obtained through the polishing of the magnetoresistive layer
5
during the manufacturing process of the ABS
18
.
In this way, the composite type thin film magnetic head in which the magnetoresistive effective type thin film magnetic head and the inductive type
Davis David
Oliff & Berridg,e PLC
TDK Corporation
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