Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-11-25
2001-12-18
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603150, C029S603180, C216S022000, C360S112000
Reexamination Certificate
active
06330743
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 combination or composite or hybrid 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. The present invention also relates to a method of manufacturing such a 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 has been 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 semi-conductor 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 electrically a thin film coil from the air bearing surface. It has been required to shorten this distance as small as possible. Also this throat height TH is determined by an amount of polishing the air bearing surface.
FIGS. 1-13
show successive steps of a known method of manufacturing a conventional typical thin film magnetic head. This magnetic head belongs to a combination 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.
At first, as illustrated in
FIG. 1
, on a substrate
11
made of a hard non-magnetic material such as aluminum-titan-carbon (AlTiC), is deposited an insulating layer
12
made of alumina (Al
2
O
3
) and having a thickness of about 3-10 &mgr;m. Then, as depicted in
FIG. 2
, a bottom shield layer
13
constituting a magnetic shield for protecting the MR reproducing magnetic head from an external magnetic field is formed to have a thickness of about 2-3 &mgr;m on the insulating layer.
Then, after depositing by sputtering a shield gap layer
14
made of an alumina with a thickness of 100-150 nm as shown in
FIG. 3
, a magnetoresistive layer
15
having a thickness of several tens nano meters and being made of a material having the magnetoresistive effect, and the magnetoresistive layer is shaped into a desired pattern by a highly precise mask alignment.
Next, as represented in
FIG. 4
, a shield gap layer
16
having a thickness of about 100-150 nm is formed such that the electro-magnetic layer
15
is embedded within the shield gap layers
14
and
16
.
Then a magnetic layer
17
made of a permalloy and having a thickness of 3-4 &mgr;m is formed 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 illustrated in
FIG. 6
, on the first magnetic layer
17
, a write gap layer
18
made of a nonmagnetic material such as alumina to have a thickness of about 150-300 nm, and then an electrically insulating photoresist layer
19
is formed on the write gap layer
18
, said photoresist layer
19
being shaped into a desired pattern by means of a highly precise mask alignment.
Next, a first layer thin film coil
20
made of, for instance Cu is formed on the photoresist layer
19
.
Next, as depicted in
FIG. 7
, an electrically insulating photoresist layer
21
is formed on the thin film coil
20
by a highly precise mask alignment, and then a surface of the photoresist layer
21
is flattened by baking it at a temperature of, for instance 250° C.
Furthermore, as shown in
FIG. 8
, on the thus flattened surface of the photoresist layer
21
, a second layer thin film coil
22
is formed. Then, a photoresist layer
23
is formed on the second layer thin film coil
22
by a highly precise mask alignment, and a baking process is conducted again at a temperature of, for instance 250° C.
A reason for forming the photoresist layers
19
,
21
and
23
by a highly precise mask alignment is that the throat height TH and MR height are determined with respect to edges of these photoresist layers on a side of the pole portion as will be explained later.
Next, as shown in
FIG. 9
, a second magnetic layer
24
made of, for instance a permalloy is selectively formed on the write gap layer
18
and photoresist layers
19
,
21
and
23
such that the second magnetic layer has a thickness of 3-4 &mgr;m and is shaped into a desired pattern.
The second magnetic layer
24
is brought into contact with the first magnetic layer
17
at a position remote from the pole portion, and therefore the thin film coil
20
,
22
pass through a closed magnetic yoke structure constituted by the first and second magnetic layers. The second magnetic layer
24
includes a pole portion which defines a width of a track on a magnetic record medium. Furthermore, an overcoat layer
25
made of an alumina is deposited on an exposed surface of the second magnetic layer
24
.
Finally, a side wall
26
of an assembly at which the magneto-resistive layer
15
and gap layer
8
are formed is polished to form an air bearing surface (ABS)
27
as shown in FIG.
10
. During the formation of the air bearing surface
27
, the magnetoresistive layer
15
is also polished to obtain an MR reproducing element
28
. In this manner, the above mentioned throat height TH and MR height MRH are determined by the polishing. In an actual manufacturing process
Iijima Atsushi
Sasaki Yoshitaka
Oliff & Berridg,e PLC
TDK Corporation
Trinh Minh
Young Lee
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