Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-04-06
2002-12-03
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S122000
Reexamination Certificate
active
06490130
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head and a method of manufacturing the same, and more particularly to a composite type thin film magnetic head constructed by stacking an inductive type thin film writing magnetic head and a magnetoresistive type reading magnetic head one on the other and a method of manufacturing such a composite type thin film magnetic head.
2. Description of the Related Art
Recently a surface recording density of a hard disc device has been improved, and it has been required to develop a thin film magnetic head having an improved performance accordingly. In order to improve a performance of a reading magnetic head, a reproducing head utilizing a magnetoresistive effect has been widely used. As the reproducing magnetic head utilizing the magnetoresistive effect, an AMR reproducing element utilizing a conventional anisotropic magnetoresistive (AMR) effect has been widely used. There has been further developed a GMR reproducing element utilizing a giant magnetoresistive (GMR) effect having a resistance change ratio higher than the normal anisotropic magnetoresistive effect by several times. In the present specification, these AMR and GMR reproducing elements are termed as a magnetoresistive reproducing element or MR reproducing element.
By using the AMR reproducing element, a very high surface recording density of several gigabits per a unit square inch has been realized, and a surface recording density can be further increased by using the GMR element. By increasing a surface recording density in this manner, it is possible to realize a hard disc device which has a very large storage capacity of more than 10 gigabytes and is still small in size.
A height of a magnetoresistive reproducing element is one of factors which determine a performance of a reproducing head including a magnetoresistive reproducing element. This height is generally called MR Height, here denoted by MRH. The MR height MRH is a distance measured from an air bearing surface on which one edge of the magnetoresistive reproducing element is exposed to the other edge of the element remote from the air bearing surface. During a manufacturing process of the magnetic head, a desired MR height MRH can be obtained by controlling an amount of polishing the air bearing surface.
At the same time, a performance of a recording head is also required to be improved. In order to increase a surface recording density, it is necessary to make a track density on a magnetic record medium as high as possible. For this purpose, a width of a pole portion at the air bearing surface has to be reduced to a value within a range from several micron meters to several sub-micron meters. In order to satisfy such a requirement, the semiconductor manufacturing process has been adopted for manufacturing the thin film magnetic head.
One of factors determining a performance of an inductive type thin film writing magnetic film is a throat height TH. This throat height TH is a distance of a pole portion measured from the air bearing surface to an edge of an insulating layer which serves to separate a thin film coil from the air bearing surface. It has been required to shorten this distance as small as possible.
FIGS. 1-12
show successive steps of a known method of manufacturing a conventional typical thin film magnetic head and a completed magnetic head. This magnetic head belongs to a composite type thin film magnetic head which is constructed by stacking an inductive type thin film writing magnetic head and a magnetoresistive type thin film reading magnetic head one on the other. In a practical process of manufacturing the thin film magnetic head, a number of thin film magnetic heads are simultaneously formed on a single wafer, and therefore end faces of respective magnetic heads do not appear. However, for the sake of explanation, the end face is shown in the drawings.
At first, as illustrated in
FIG. 1
, on a substrate
11
made of an electrically insulating and non-magnetic material such as aluminum-titan-carbon (AlTiC), is deposited on an insulating layer
12
made of alumina (Al
2
O
3
) and having a thickness of about 5-10 &mgr;m. Then, as depicted in
FIG. 2
, after forming a bottom shield layer
13
constituting a magnetic shield for the MR reproducing magnetic head and having a thickness of about 3 &mgr;m on the insulating layer, an insulating layer
14
is formed by depositing an alumina with a thickness of 100-150 nm as shown in FIG.
3
.
As illustrated in
FIG. 3
, on the insulating layer
14
, is formed a magnetoresistive layer
15
having a thickness of several tens nanometers (nm) and being made of a material having the magnetoresistive effect, and the magnetoresistive layer is shaped into a desired pattern by a precise mask alignment. Next, as represented in
FIG. 4
, an alumina insulating layer
16
like as the alumina insulating layer
14
is formed by sputtering to have a thickness of 100-150 nm, and then a magnetic layer
17
made of a permalloy and having a thickness of 3-4 &mgr;m is formed on the alumina insulating layer as shown in FIG.
5
. This magnetic layer
17
serves not only as an upper shield layer for magnetically shielding the MR reproducing element together with the above mentioned bottom shield layer
13
, but also as a bottom magnetic layer of the inductive type writing thin film magnetic head to be manufactured later. Here, for the sake of explanation, the magnetic layer
17
is called a first magnetic layer, because this magnetic layer constitutes one of magnetic layers forming the thin film writing magnetic head.
Next, as shown in
FIG. 6
, on the first magnetic layer
17
, is formed a gap layer
18
made of a nonmagnetic material such as alumina to have a thickness of about 150-300 nm by sputtering. An electrically insulating photo-resist layer
19
is formed on the write gap layer
18
and is shaped into a desired pattern by a highly precise mask alignment. On the photo-resist layer there is formed a first thin film coil layer
20
made of, for instance copper.
Next, as illustrated in
FIG. 7
, an electrically insulating photo-resist layer
21
is formed on the first thin film coil layer
20
by an highly precise mask alignment, and then the photo-resist layer is baked at, for instance 250° C. in order to flatten its surface. On the thus flattened surface of the photo-resist layer
21
, is formed a second thin film coil layer
22
and a photo-resist layer
23
is formed on the second thin film coil layer
22
by a highly precise mask alignment. Then, the photo-resist layer
23
is baked at, for instance 250° C. such that its surface is flattened as shown in
FIG. 8. A
reason for forming the photo-resist layers
19
,
21
and
23
with a highly precise mask alignment as stated above is that the throat height TH and MR height MRH are defined on the basis of edge positions of these photo-resist layers.
Next, as illustrated in
FIG. 9
, on the gap layer
18
and photo-resist layers
19
,
21
and
23
, a second magnetic layer
24
made of a permalloy and having a thickness of 3-4 &mgr;m is selectively formed in accordance with a desired pattern. This second magnetic layer
24
is brought into contact with the first magnetic layer
17
at a position remote from the magnetoresistive layer
15
, and the thin film coils
20
,
22
pass through a closed magnetic path constituted by the first and second magnetic layers. A pole portion of the second magnetic layer
24
is formed into desired shape and size which define a track width. Furthermore. an overcoat layer
25
made of alumina is formed on exposed surfaces of the second magnetic layer
24
and gap layer
18
by sputtering. Finally, a side wall
26
at which the magnetoresistive layer
1
is formed is polished to form an air bearing surface (ABS)
27
as depicted in
FIG. 10
, said air bearing surface opposing to a record medium. During the formation of the air bearing surface
27
, the magnetoresistive layer
15
is also polished to obtain an MR reproducing elemen
Iijima Atsushi
Sasaki Yoshitaka
Evans Jefferson
Oliff & Berridg,e PLC
TDK Corporation
LandOfFree
Thin film magnetic head with recess for positional reference does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin film magnetic head with recess for positional reference, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head with recess for positional reference will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2937927