Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
2002-02-01
2003-05-06
Mills, Gregory (Department: 1763)
Etching a substrate: processes
Forming or treating article containing magnetically...
C029S603140, C029S603150, C438S003000
Reexamination Certificate
active
06558561
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head including a inductive type writing thin film magnetic head and a method of manufacturing the same, and more particularly relates to a combination type thin film magnetic head constructed by stacking an inductive type writing thin film magnetic head and a magneto-resistive type reading thin film magnetic head on a surface of a substrate and a method of manufacturing such a combination 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. 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, 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, such AMR and GMR elements are termed as a magnetoresistive reproducing element or simply as 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 ten gigabytes.
A height of a magnetoresistive reproducing element, i.e. MR Height(MRH) 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 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. 1-9
show successive steps of a 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
FIG. 1
, an alumina (Al
2
O
3
) insulating layer
2
having a thickness of about 5-10 &mgr;m is deposited on a substance
1
made of, for instance AlTiC.
Next, as shown in
FIG. 2
, 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 3 &mgr;m.
Then, as shown in
FIG. 3
, 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, as shown in the
FIG. 4
, an insulating layer
6
is formed again such that the magnetoresistive layer
5
is embedded within the insulating layers
4
and
6
.
Next, as shown in the
FIG. 5
, a second magnetic layer
7
made of a permalloy is formed with a thickness of 3 &mgr;m. This second magnetic layer
7
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, on the second magnetic layer
7
, is formed a write gap layer
8
made of a non-magnetic material such as alumina and having a thickness of about 200 nm, and then after forming a magnetic layer 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), this magnetic layer is shaped into a desired pattern by means of the highly precise mask alignment to constitute a pole chip
9
. A track width is determined by a width W of the pole chip
9
. Therefore, in order to attain a higher surface recording density, this width W should be made as small as possible.
During the above process, it is preferable to form a dummy pattern
9
′ which will connect the second magnetic layer
7
to a third magnetic layer. Then, a through hole may be easily formed after mechanical polishing or chemical-mechanical polishing (CMP).
In order to prevent an effective record track width from being widened, that is to say, in order to avoid a spread of a magnetic flux at one of the poles upon writing, a part of the write gap layer
8
surrounding the pole chip
9
as well as the second magnetic layer
7
constituting one of the poles are etched by means of an ion beam etching such as an ion milling. This condition is shown in
FIG. 5
, and this structure is called a trim structure. This part of the second magnetic layer
7
serves as the pole portion.
Next, as illustrated in
FIG. 6
, an insulating layer, e.g. alumina layer
10
is formed with a thickness of about 3 &mgr;m, and then an assembly is flattened by CMP.
After that, after forming an electrically insulating photoresist layer
11
into a given pattern by means of the highly precise mask alignment, a first layer thin film coil
12
made of, for instance a copper is formed on the photoresist layer
11
.
Continuously, as shown in
FIG. 7
, after forming an electrically insulating photoresist layer
13
on the thin film coil
12
by the highly precise mask alignment, the photoresist layer is sintered at a temperature of, for example 250-300° C. to obtain a flat surface.
In addition, as shown in
FIG. 8
, a second layer thin film coil
14
is
Culbert Roberts P
Mills Gregory
Oliff & Berridg,e PLC
TDK Corporation
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