Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-11-10
2002-09-03
Ometz, David L. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C029S603150, C216S066000
Reexamination Certificate
active
06445550
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head, and particularly, to a method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head which can form a recording head more precisely to a reading head.
2. Description of the Prior Art
Magnetoresistive heads using a magnetoresistive effect have attracted much public attention as a key device for promoting miniaturization of recent hard magnetic disk devices and increase of the memory capacity thereof, and of these heads, a magnetoresistive head using such a spin valve effect that the resistance change corresponds to the cosine between magnetization directions of two adjacent magnetic layers is being actively developed because it exhibits a large resistance change under application of a small signal magnetic field.
FIG. 1
shows the most practical structure of this head. As shown in
FIG. 1
, there has been known a magnetoresistive/inductive composite head including a magnetoresistive head and an inductive head.
The magnetoresistive head includes a pair of confronting magnetic shields
1
and
6
and magnetoresistive element
3
that is disposed in the gap between the magnetic shields
1
and
6
. The magnetoresistive element
3
senses magnetic field occurring above a magnetic recording medium. The magnetic shields
1
and
6
and the magnetoresistive element
3
are disposed through reading magnetic gaps
2
a
and
2
b.
The inductive head includes the magnetic shield
6
serving as one magnetic pole (hereinafter, number
6
is indicated as a magnetic shield or a magnetic pole), another magnetic pole
8
disposed at the opposite side to the magnetoresistive element
3
with respect to the magnetic pole
6
, a coil (not shown) for exciting the magnetic poles
6
and
8
. The inductive head writes information on a magnetic recording medium by magnetic field occurring from writing magnetic gap
7
provided between the magnetic poles
6
and
8
.
It has been known that a side fringe magnetic field that is not negligible occurs for writing information in such a composite type head as described above. The width of magnetic pole
6
which also serves as the magnetic shield is designed to be larger than the width of the magnetic pole
8
which inherently defines the writing width for information, and thus the magnetic flux leaks to the extra portion of the magnetic pole
6
which is beyond the magnetic pole
8
in width, resulting in occurrence of the side fringe magnetic field. The side fringe magnetic field thus occurring restricts the minimum writing width achievable. Therefore, in order to achieve a higher recording density, the composite type head must be designed so as to reduce the side fringe magnetic field at maximum. A method of reducing the side fringe magnetic field has been disclosed in Japanese Laid-open Patent Publication No. 7-262519.
According to the method disclosed in the publication, as shown in
FIG. 2
, the magnetic pole
6
is etched until a proper depth by an ion beam milling while the magnetic pole
8
is used as a mask so that the adjacent portion of the magnetic pole
6
to the writing gap
7
is cut so as to be identically with the magnetic pole
8
in width, thereby suppressing the side fringe magnetic field. However, with this method, the magnetic pole
8
is etched simultaneously with the etching process of the magnetic pole
6
as shown in
FIG. 2
, resulting in remarkable reduction of the film thickness of the magnetic pole
8
. The reduction of the film thickness of the magnetic pole
8
may induce degradation of the writing characteristic due to a magnetic saturation phenomenon of the magnetic pole, etc. Accordingly, in order to finally obtain the magnetic pole
8
having a film thickness enough to a desired writing characteristic, the magnetic pole
8
is formed so as to have an extra film thickness by a flame plating method while the reduction amount of the film thickness is estimated in advance for the magnetic pole
8
. That is, in order to achieve the above object, the frame height must be set to a large value. If the frame height is kept large, it would generally disturb reduction of the frame interval, that is, reduction of the writing width. In Japanese Laid-open Patent Publication No. 7-262519, the upper limit of the reduction of the writing width based on this method is equal to 2 &mgr;m, and it is difficult to obtain a writing width less than 2 &mgr;m.
Japanese Laid-open Patent Publication No. 5-143927 discloses a method of solving the above problem. According to this method, the writing width is specified by an ion beam etching from the confronting face side to the medium in a bar processing step after a wafer step is completed. In this method, a desired writing width can be achieved independently of the thickness of the magnetic pole
8
, and thus there can be easily obtained such a structure that both of the reduction of the writing width and the reduction of the side fringe magnetic field can be achieved.
It has been increasingly required to strictly manage the relative positional relationship between the writing track position of the inductive head for performing an information writing operation and the reading track position of the magnetoresistive head for performing an information reading operation. This requirement is made to perform an ideal information reading/writing operation in a magnetic disk device, and the management of the positional relationship is more increasingly required to be performed with precision of 0.1, &mgr;m particularly as the writing width is reduced to 1 &mgr;m or less. With respect to this point, Japanese Laid-open Patent Publication No. 5-143927 teaches that a mark indicating the position of the reading track is located at an observable position in a magnetic pole processing step based on the ion beam etching. Furthermore, it discloses as a mark forming method a method of forming a predetermined mark in another step by using a photoresist mask having the same pattern as a photoresist mask used to determine the position of the reading track. However, in this method, the mark forming step and the reading track position determining step are not the same step, and thus a measure of dispersion remains in the alignment between both the photoresist masks even though the photoresist masks have the same pattern. Accordingly, even when the processing step of the writing pole is carried out on the basis of the mark, it cannot directly guarantee the positional relationship between the reading track and the writing track.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head which can overcome the disadvantage of the prior art and reduce the side fringe magnetic field, and also can strictly manage the positional relationship between a writing track position and a reading track position particularly even under a narrow-width state that the writing width is equal to 1 &mgr;m or less.
In order to achieve the above object, according to the present invention, there is provided a method of manufacturing a magnetoresistive/inductive composite head comprising a step of forming a magnetoresistive head which comprises a magnetoresistive element for sensing magnetic field occurring above a magnetic recording medium and an electrode portion for supplying sense current to the magnetoresistive element, the magnetoresistive element and the electrode portion being disposed between a pair of first and second magnetic shields disposed so as to confront each other through magnetic gaps; a step of forming an inductive head which comprises a first magnetic pole using the second magnetic shield as a magnetic pole, a second magnetic pole disposed at the opposite side to the magnetoresistive element with respect to the second magnetic shield an
McGinn & Gibb PLLC
NEC Corporation
Ometz David L.
LandOfFree
Method of manufacturing magnetoresistive/inductive composite... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing magnetoresistive/inductive composite..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing magnetoresistive/inductive composite... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2855603