Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2003-03-31
2004-06-22
Huson, Gregory L. (Department: 3751)
Metal working
Method of mechanical manufacture
Electrical device making
Reexamination Certificate
active
06751846
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic head manufacturing method and a magnetic head used in a magnetic disc device.
The recording density upon recording information on magnetic recording media are under progress. For HDD (hard disc drive), a system having the recording density as high as 5 to 7 Gbit/inch
2
has actually been brought into practice for HDD (hard disc drive), and higher densities are still being demanded. An answer to this demand is to realize a magnetic head with “narrow tracks” whose recording track width is not larger than 1 &mgr;m.
Also for thin-film magnetic head incorporating recording and reproducing functions, various structures have been proposed toward realization of narrow tracks.
For example, Japanese Patent Laid-Open Publication No. H10-214407 discloses a record/reproduce integral thin-film magnetic head having the structure shown in FIG.
42
.
FIG. 42
is an elevational view which shows the medium facing surface of the record/reproduce integral thin-film magnetic head. Formed on a substrate (not shown) is a lower magnetic shield layer
1
made of a soft-magnetic material. Formed on the lower magnetic shield
1
is a magnetoresistance effect film (MR film) via a lower reproducing magnetic gap
2
made of a non-magnetic insulating material. A pair of leads
4
are connected to opposite ends of the MR film
3
. These elements constitute a MR element portion
5
. Formed on the MR element portion
5
is an upper reproducing gap
6
made of a non-magnetic insulating material. Further formed thereon is an upper magnetic shield layer
7
made of the same material as that of the lower magnetic shield layer
1
. These elements constitutes a shield type MR head
8
which functions as a reproducing head.
On the reproducing head made up of the shield type MR head
8
, a recording head made up of an inductive-type thin-film magnetic head
9
. These elements constitutes a record/reproduce integral magnetic head
10
.
The lower write pole of the inductive-type thin-film magnetic head
9
is composed of the soft-magnetic layer forming the upper magnetic shield layer
7
on the shield type MR head
8
. That is, the upper magnetic shield layer
7
also functions as the lower write pole of the recording head. On the lower write pole
7
commonly used as the upper magnetic shield layer (hereinbelow simply called lower write pole), a write magnetic gap
12
made of a non-magnetic material is provided. The lower write pole
7
has a projection as a magnetic pole tip portion (gap facing portion)
11
. The top surface of the projecting lower tip portion
11
for contact with the write magnetic gap
12
has the width corresponding to the record track width Tw. The write magnetic gap
12
is formed to extend along the contour of the lower write pole having the projecting lower write pole tip portion
11
. A non-magnetic material layer
13
is formed to sandwich the lower write pole tip portion (projection)
11
including the write magnetic gap
12
from track width directions. The non-magnetic material layer
13
has a recess
14
positionally aligned with the projection
1
. The recess
14
is buried with the magnetic material which constitutes the upper magnetic tip portion
16
of the upper write pole
15
. The upper write pole tip portion
16
projects toward the write magnetic gap
12
. On the back side (remoter from the viewer of
FIG. 42
) of the upper write pole
15
including the magnetic pole tip portion
16
buried in the recess
14
, a coil (not shown) buried in an insulating layer is provided on the non-magnetic material layer
13
. These components explained above make up the record/reproduce integral magnetic head
10
.
In magnetic heads having this type of structure, the tip portion
11
of the lower write pole and the tip portion
16
of the upper write pole opposed to each other via the write magnetic gap
12
are equal in width. Therefore, it is free from the problem which occurs upon making narrower tracks in magnetic heads in which the upper write pole and the lower write pole are different in width, that it, the problem of offsets of record bit lines at edges due to a leak magnetic field from the record track side and reproduction writing.
In the record/reproduce integral magnetic head shown in
FIG. 42
, the top end of the lower magnetic head
7
is previously shaped to project, the non-magnetic material layer
13
is formed to have a recess above the projection, and a magnetic material is buried in the recess and used as the upper write pole
15
.
Although various methods such as plating and collimation sputtering are considered usable for making the upper write pole
15
to bury the recess, plating is much more advantageous than others because of the low process cost and its actual results. However, in order to bury and make the upper write pole
15
without any empty spaces, it is necessary to previously provide a conductive layer in the recess, which is used as a plating electrode film.
For this purpose, it would be possible to use the method which makes the write magnetic gap
12
by a conductive material and buries in one recess the lower write pole tip portion
11
, write magnetic gap
12
and upper write pole tip portion
16
altogether by plating. However, if a conductive film is used as the write magnetic gap
12
, an overcurrent loss occurs, and the magnetic property of the magnetic head degrades.
Additionally, in the case where the width of the upper write pole tip portion
16
is narrower than the width of the top portion (supplemental magnetic pole
15
B) of the upper write pole
15
as shown in
FIG. 42
, intensity of the magnetic field which leaks from corners E made by the upper write-pole
15
on the side nearer to the magnetic gap is liable to increase, and causes the problem that, during writing of a signal into the recording medium, it is written to an adjacent track, or information on an adjacent track is erased.
On the other hand, when the upper write pole
15
shown in
FIG. 42
is made, U.S. Pat. No. 5,283,942, among others, teaches first forming a layer mainly forming the upper write pole tip portion
16
and thereafter making the remainder layer mainly used as the supplemental magnetic pole
15
B. In this case, the interface where the layer first made and the remainder layer connect (which lies in the level shown by the broken line A in
FIG. 42
) comes inside the upper write pole tip portion
16
or approximately lies on the boundary between the upper write pole tip portion
16
and the supplemental magnetic pole
15
B.
However, along the interface between the layer previously made and the remainder layer, there often remain a deteriorated layer made on the surface of the previously stacked layer by oxidation and layers of non-magnetic material such as base layer required for making the remainder layer, although they are thin in thickness. Therefore, the interface between the previously stacked layer and the remainder layer results in lying on the boundary between the upper write pole tip portion
16
and the supplemental magnetic pole
15
B, to which is the magnetic flux is concentrated more, and this portion behaves as a pseudo boundary and causes leakage of the magnetic flux and deterioration of the magnetic property thereby.
SUMMARY OF THE INVENTION
This invention has been made remarking these problems.
The first object of the invention is to provide a manufacturing method of a magnetic head, which is effective for manufacturing a record/reproduce integral magnetic head having a head structure suitable for narrower tracks and a higher line recording density, by previously shaping an upper portion of a lower recording magnetic pole to project from the other part so as to bury and form an upper write pole in a recess of a non-magnetic material layer formed above the projection in a self-alignment fashion, and ensures that the upper write pole be made with a good buried property and that the magnetic head be excellent in magnetic property as well.
The second object of the invention is to provide a
Hara Michiko
Hashimoto Susumu
Hori Akio
Koizumi Takashi
Nagata Tomohiko
Foley & Lardner LLP
Huson Gregory L.
Le Huyen
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