Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1998-07-17
2001-02-20
Letscher, George J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Core
C360S123090
Reexamination Certificate
active
06191916
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, particularly to an inductive type writing magnetic transducing element and a method of manufacturing the same.
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. A hybrid or composite or combination type thin film magnetic head is constructed by stacking, on a substrate, an inductive type thin film magnetic head intended for writing and a magnetoresistive type thin film magnetic head intended for reading, and has been practically used. In general, as a reading magnetoresistive element, an element utilizing anisotropic magnetoresistive (AMR) effect has been used so far, but there has been further developed a GMR reproducing element utilizing a giant magnetoresistive (GMR) effect having a resistance change ratio higher than that of the normal anisotropic magnetoresistive effect by several times. In the present specification, elements exhibiting a magnetoresistive effect such as 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/inch
2
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.
A height (MR Height: MRH) of a magnetoresistive reproducing element is one of factors which determine a performance of a reproducing head including a magnetoresistive reproducing element. 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, the performance of the recording magnetic head is also required to be improved in accordance with the improvement of the performance of the reproducing magnetic head. 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 write gap 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 the performance of the inductive type thin film writing magnetic head is a throat height (TH). This throat height 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. The reduction of this throat height is also decided by an amount of polishing the air bearing surface.
In order to improve the performance of the inductive type thin film writing magnetic head, there has been proposed to reduce a length of portions of the bottom pole and top pole surrounding the thin film coil (in the present specification, said length is termed as magnetic path length).
FIGS. 1-8
show successive steps for manufacturing a conventional typical inductive type thin film magnetic head, these drawings showing a cross-sectional view cut along a line perpendicular to the air bearing surface. It should be noted that in this combination type thin film magnetic head, the inductive type thin film magnetic head for writing is stacked on the reproducing MR element.
First of all, as shown in
FIG. 1
, an insulating layer
2
consisting of, for example alumina (Al
2
O
3
) and having a thickness of about 5-10 &mgr;m is deposited on a substance
1
made of a non-magnetic and electrically insulating material such as aluminum-titanium-carbon (AlTiC). A bottom shield layer
3
constituting a magnetic shield which protects the GMR reproducting element of the reproducing head from the influence of an external magnetic field, is formed with a thickness of 3-4 &mgr;m. Next, a GMR layer
5
having a thickness of several tens nano meters is formed on the bottom shield such that the GMR layer is embedded in a shield gap layer
4
. Then, a magnetic layer
6
made of a permalloy is formed with a film thickness of 3-4 &mgr;m. This magnetic layer
6
has not only the function of the upper shield layer which magnetically shields the GMR reproducing element together with the above described lower shield layer
3
, but also has the function of a bottom pole of the writing thin film magnetic head. Here, for sake of explanation, the magnetic layer
6
is called a first magnetic layer by taking into account the fact that this magnetic layer constitutes one of the poles of the writing magnetic head.
Then, as shown in
FIG. 2
, a write gap layer
7
made of a non-magnetic material such as alumina and having a thickness of about 200 nm is formed on the first magnetic layer
6
. A photoresist
8
is formed on the write gap layer
7
at an area except for a potion corresponding to the pole portion to be formed later, said photoresist determining a reference position for the throat height. Next, a thin copper layer
9
having a thickness of about 100 nm is formed on a whole surface by sputtering. Thin copper layer
9
constitutes a seed layer for the formation of the thin film coil by electroplating. Therefore, this layer is also called a seed layer. On the seed layer
9
, is formed a thick photoresist
10
having a thickness of 3 &mgr;m, and an opening
11
is formed within the photoresist
10
such that the seed layer is exposed at the bottom of the opening. A height of this opening is equal to a thickness of the photoresist and is 2 &mgr;m, and a width of the opening is also 2 &mgr;m.
Next, an electroplating of copper is performed using a plating bath consisting of a copper sulfate to form first layer thin film coil windings
12
having a thickness of 2-3 &mgr;m within the opening
11
formed in the photoresist
10
as depicted in FIG.
3
. It is preferable that a thickness of the coil winding
12
is smaller than a depth of the opening
11
.
Then, as illustrated in
FIG. 4
, after removing the photoresist
10
, a milling with an argon ion beam is carried out to remove the seed layer
9
as shown in
FIG. 5
to separate the successive coil windings
12
to form a single coiled conductor. During this ion beam milling, in order that the seed layer
9
at roots of the coil windings
12
of the thin film coil is not remained, the ion beam milling is performed at an angle of 5-10°. In this manner, by conducting the ion beam milling substantially at right angles, debris of the material of the seed layer
9
are liable to be adhered to the coil windings
12
. Therefore, it is necessary to increase a distance between successive coil windings.
Next, as depicted in
FIG. 6
, a photoresist
13
is formed to cover the coil windings
12
of the first layer thin film coil, and after polishing the top surface thereof into a flat surface, coil windings
15
of a second layer thin film coil are formed on a seed layer
14
by a similar method as that described above. Furthermore, after forming a photoresist
16
, a second magnetic layer
17
made of a permalloy and having a thickness of 3-5 &mgr;m is formed, said second magnetic layer constituting the top pole.
Then, as shown in
FIGS. 7 and 8
, parts of the write gap layer
7
and first magnetic layer
6
are etched while a pole portion
17
a
of the second magnetic layer
17
is used as a mask, to form a trim structure. Furthermore, an overcoat layer
Letscher George J.
Oliff & Berridg,e PLC
TDK Corporation
LandOfFree
Thin film magnetic head and method of manufacturing the same 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 and method of manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head and method of manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2592531