Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-07-19
2003-11-25
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603130, C029S603150, C029S603180, C360S313000
Reexamination Certificate
active
06651312
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a composite type thin film magnetic head constructed by stacking an inductive type writing magnetic transducing element and a magnetoresistive type reading magnetic transducing element on a substrate.
2. Description of 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 composite 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, 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 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 composite type thin film magnetic head having the writing inductive type thin film magnetic head and reading magnetoresistive type thin film magnetic head stacked one on the other, it is important that the recording inductive type thin film magnetic head and reproducing magnetoresistive type thin film magnetic head are formed with a good balance.
FIGS. 1A-9B
show successive steps for manufacturing a conventional standard thin film magnetic head, in these drawings A depicts a cross-sectional view of a substantial portion of the head and B represent a cross sectional view of a pole portion. Moreover,
FIGS. 10-12
are a cross sectional view of a substantial portion of the completed thin film magnetic head, a cross sectional view of the pole portion, and a plan view of the substantial portion of the thin film magnetic head, respectively. It should be noted that the thin film magnetic head is of a composite type in which the inductive type thin film magnetic head for writing is stacked on the reproducing MR element.
First of all, as shown in
FIGS. 1A & B
, an insulating layer
2
consisting of, for example alumina (Al
2
O
3
) is deposited on a substance
1
made of a non-magnetic and electrically insulating material such as AlTiC and having a thickness of about 5-10 &mgr;m. Next, as shown in
FIGS. 2A & B
, a first magnetic layer
3
which constitutes one of magnetic shields protecting 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. Afterwards, as shown in
FIGS. 3A & B
, after depositing an insulating layer
4
of thickness 100-150 nm serving as a shield gap by spattering alumina, a magnetoresistive layer
5
made of a material having the magnetoresistive effect and constituting the MR reproduction element is formed on the shield gap layer with a thickness of several tens nano meters and is then shaped into a given pattern by the highly precise mask alignment.
Then, as shown in
FIGS. 4A & B
, an insulating layer
6
is formed such that the magnetoresistive layer
5
is embedded within the insulating layers
4
and
6
.
Next, as shown in
FIGS. 5A & B
, a second magnetic layer
7
made of a permalloy is formed with a film 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 lower shield layer
3
, but also has the function of one of poles of the writing thin film magnetic head.
Then, after forming a write gap layer
7
made of a non-magnetic material such as alumina and having a thickness of about 200 nm on the second magnetic layer
7
, a pole chip
9
made of a material having a high saturation magnetic flux density such as permalloy (Ni:50 wt %, Fe:50 wt %) and nitride iron (FeN) is formed with a desired shape by the highly precise mask alignment. A track width is determined by a width W of the pole chip
9
. Therefore, in order to realize a high surface recording density, it is necessary to decrease the width W. In this case, a dummy pattern
9
′ for coupling the bottom pole (first magnetic layer) with the top pole (third magnetic layer) is formed simultaneously. Then, a through-hole can be easily formed by polishing or chemical mechanical polishing (CMP).
In order to prevent an effective width of writing track from being widened, that is, in order to prevent a magnetic flux from being spread at the bottom pole upon the data writing, portions of the gap layer
8
and second magnetic layer
7
constituting the other pole surrounding the pole chip
9
are etched by an ion beam etching such as ion milling. The structure after this process is shown in
FIGS. 5A & B
. This structure is called a trim structure and this portion serves as a pole portion of the first magnetic layer.
Next, as shown in
FIGS. 6A & B
, after forming an insulating layer, for example alumina film
10
with a thickness of about 3 &mgr;m, the whole surface is flattened by, for instance CMP. Subsequently, after forming an electrically insulating photoresist layer
11
into a given pattern by the mask alignment of high precision, a first layer thin film coil
12
made of, for instance copper is formed on the photoresist layer
11
. Continuously, as shown in
FIGS. 7A & B
, 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.
In addition, as shown in
FIGS. 8A & B
, a second layer thin film coil
14
is formed on the flattened surface of the photoresist layer
13
Oliff & Berridg,e PLC
Phan Thiem Dinh
TDK Corporation
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