Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-09-01
2004-08-24
Watko, Julie Anne (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S123090, C360S119050
Reexamination Certificate
active
06781790
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 relates to an inductive type writing thin film magnetic head 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 combination type thin film magnetic head is constructed by stacking an inductive type thin film magnetic head intended for writing and a magnetoresistive type thin film magnetic head intended for reading on a substrate, and has been practically used. In general, as a reading magnetoresistive element, an element utilizing anisotropic magnetoresistive (AMR) effect has been used so far and a surface recording density of about one gigabits/inch
2
has been realized. In order to increase a surface record density, there has been further developed a 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, and a very high surface recording density of about three gigabits/inch
2
has been realized. 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 not less more than ten gigabytes.
The reproducing thin film magnetic head including the above mentioned GMR element has a same structure as the reproducing thin film magnetic head having the AMR element, and the AMR element is merely replaced by the GMR element. It should be noted that in the GMR element, a reproduced output is higher than that of the AMR element by 3-5 times under a same external magnetic field. The GMR film has a multiple layer structure including several films. The film structure of the GMR changes depending upon a mechanism producing the GMR effect. There have been proposed the super-lattice GMT film, glanular film, and so on. The spin valve film will be predominant owing to its simple structure, a large resistance change under a weak magnetic field and a large scale manufacture.
As stated above, a surface recording density can be simply increased by changing the AMR element by the GMR element as long as the reproducing thin film magnetic head is concerned. A height of a magnetoresistive reproducing element, i.e. MR Height (MRH) is one of factors determining a performance of the 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, 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 writing thin film magnetic head 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. The reduction of this throat height is also decided by an amount of polishing the air bearing surface.
Therefore, in order to improve the performance of the combination type thin film magnetic head having the inductive type recording head and magnetoresistive reading head stacked one on the other, it is very important to make the performance of the recording head and the performance of the reading head to be balanced with each other.
FIGS. 1A-7B
show successive steps of a known method of manufacturing a conventional standard thin film magnetic head. In these drawings, A represents a cross sectional view cut along a plane perpendicular to the air bearing surface and B denotes a cross sectional view of a pole portion cut along a plane parallel to the air bearing surface.
FIGS. 10-12
are cross sectional and plan views showing a finally manufactured completed thin film magnetic head. It should be noted that the thin film magnetic head is of a combination type in which the inductive type writing thin film magnetic head and reproducing MR element are stacked one on the other.
First of all, as shown in
FIGS. 1A-B
, an alumina (Al
2
O
3
) insulating layer
2
having a thickness of about 5 &mgr;m is deposited on a substance
1
made of, for instance AlTiC. Next, a first magnetic layer
3
constituting a bottom shield which protects the MR reproduction element of the reproducing head from the influence of an external magnetic field, is formed with a thickness of about 3 &mgr;m.
Then, as shown in
FIGS. 2A-B
, after depositing an alumina insulating layer
4
of thickness 100-150 nm by sputtering, a magnetoresistive layer
5
made of a material having the magnetoresistive effect and constituting the MR reproduction element is formed with a thickness not larger than ten nano meters, and is then shaped into a given pattern by the highly precise mask alignment. Then, lead electrodes
6
a
,
6
b
are formed. Next, an alumina insulating layer
7
constituting a top shield gap layer is formed with a thickness of 100-150 nm by sputtering such that the GMR layer
5
is embedded within the insulating layers
4
,
7
. Furthermore, a second magnetic layer
8
made of a permalloy is formed with a thickness of about 3 &mgr;m. This second magnetic layer
8
has not only the function of the upper shield layer which magnetically shields the MR reproduction element together with the above described first magnetic layer
3
, but also has the function of one of poles of the writing thin film magnetic head.
Then, as illustrated in
FIGS. 3A-B
, on the second magnetic layer
8
, is formed a write gap layer
9
made of a non-magnetic material such as alumina and having a thickness of about 200 nm. Then, a photoresist layer
10
having a large thickness of 1.0-1.5 &mgr;m is formed by the electroplating, and a thin film coil
11
is formed by electroplating with a thickness of 1.5-2.0 &mgr;m as shown in
FIGS. 4A-B
. After that, as shown in
FIGS. 5A-B
, a photoresist insulating layer
12
is formed such that the thin film coil
11
is supported thereby in an electrically isolated manner. During this process, a reference position TH
0
of throat height zero is determined by a pattern edge of the insulating layer
12
. Further, an apex angle &thgr; is determined by a height of the thin film coil
11
and a configuration of a side wall of the insulating layers
10
,
12
. The apex angle &thgr; can be reduced to 25-35° by increasing a distance from the reference position TH
0
of throat height zero to the outermost edge of the thin film coil
12
. By reducing the apex angle &thgr;, the pole portion of the writing thin film magnetic head can be formed precisely by photolithography and a width of the write track determined by a width of the pole portion can be shortened.
Next, as depicted in
FIG. 6
, a third magnetic layer
13
made of a magnetic material having a high saturation magnetic flux density such as a permalloy (Ni:50 wt %, Fe:50 wt %) and an iron nitride (FeN) is deposited with a thickness of about 3 &mgr;m. In this manner, a top pole is formed. During this process, the se
Oliff & Berridg,e PLC
TDK Corporation
Watko Julie Anne
LandOfFree
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