Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2002-03-07
2004-06-22
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S320000, C360S322000
Reexamination Certificate
active
06754055
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a giant magneto-resistive effect element and also relates to a magneto-resistive effect type head, a thin-film magnetic memory and a thin-film magnetic sensor including this giant magneto-resistive effect element.
2. Description of the Related Art
At present, as a high-density magnetic recording device such as a hard disk drive, there is adopted a so-called merge type composite magnetic head which is provided by combining an inductive type write magnetic head and a read magnetic head utilized a magneto-resistive effect (magneto-resistive effect type head).
FIG. 1
of the accompanying drawings is a schematic perspective view illustrating an arrangement of a merge type composite magnetic head. A gap film and an insulating film are not shown in FIG.
1
.
As show in
FIG. 1
, a magnetic sensing element
53
is disposed on a lower shield
52
made of a magnetic material formed on a substrate
51
, and an upper shield
54
made of a magnetic material is formed on an upper layer.
The lower shield
52
, the magnetic sensing element
53
and the upper shield
54
constitute a read magnetic head
61
as a lower layer magnetic head. As the magnetic sensing element
53
, there is used an element having a magneto-resistive effect, i.e., a magneto-resistive effect element (MR element).
The upper shield
54
serves also as a lower layer magnetic core of a recording upper magnetic head, and a tip end pole portion
55
is disposed above the upper shield
54
. An upper layer magnetic core
57
is connected onto the tip end pole portion
55
. Further, a back yoke
58
is connected to the rear portion of the upper layer magnetic core
57
. Then, a coil
56
is disposed among the lower layer magnetic core
54
, the upper layer magnetic core
57
and the back yoke
58
through an insulating layer.
The lower layer magnetic core
54
, the coil
56
, the tip end pole portion
55
, the upper layer magnetic core
57
and the back yoke
58
constitute and inductive type write magnetic head
62
as an upper magnetic head.
Then, a merge type composite magnetic head
50
is constructed by laminating the read magnetic head
61
of the lower layer and the write magnetic head
62
of the upper layer.
As a magneto-resistive effect element (MR element) for use as a magneto-resistive effect type head comprising the read magnetic head
61
of the lower layer of this composite magnetic head
50
, there is recently used a giant magneto-resistive effect element (GMR element) which can demonstrate a higher sensitivity.
The GMR element which becomes commercially available at present is used in a so-called CIP (current in plane) mode in which a sense current for detecting a magneto-resistive effect flows in the direction parallel to the film plane of the laminated layer film.
However, in the arrangement of the CIP type GMR element which is used in this CIP mode, when a recording density is further increased from now on, there will be a limit on increasing a recording density in rear future from a standpoint of electrical short-circuit between a shield film and a hard film to which the sense current flows, an electromigration and so forth.
From this background, recently, there has been examined a CPP type GMR element which may be used in a so-called CPP (current perpendicular to the plane) mode in which a sense current flows to the direction perpendicular to the film plane of the laminated layer film of the GMR element.
Since the CPP type GMR element uses a shield film as an electrode, an insulating layer between the shield layer and the GMR element can be removed, the above-mentioned problem of the electrical short-circuit can be solved fundamentally.
Moreover, since the CPP type GMR element can increase its area in which it comes in contact with an electrode film formed of a metal film having an excellent thermal conduction, this CPP type GMR element has a characteristic such that an electromigration becomes difficult to occur at a remarkably higher current density as compared with the CIP type GMR element. Therefore, it may be considered that this CPP type GMR element becomes able to realize a narrow gap and a narrow track width which are the requirements of the high density recording magnetic head.
FIG. 2
is a schematic diagram (cross-sectional view) of the GMR element which can be used in this CPP mode.
In the arrangement of the CPP type GMR element shown in
FIG. 2
, a conductive hard magnetic material is used as a hard magnetic film (hard film) which is useful for stabilizing the GMR element.
As shown in
FIG. 2
, on a lower magnetic shield
71
made of a magnetic material, there is deposited a GMR element
73
whose cross-section is a trapezoid through a lower gap film
72
made of a non-magnetic conductive material and which serves also as an electrode film. Although not shown, this GMR element
73
is comprised of a laminated layer film of a magnetic film and a non-magnetic film. On the right and left of the GMR element
73
, there are disposed hard magnetic films
77
made of a conductive hard magnetic material through insulating films
76
such as alumina films. The insulating films
76
are adapted to insulate the GMR element
73
and the conductive hard magnetic films
77
from each other. On the hard magnetic films
77
, there are deposited insulating layers
78
over the GMR element
73
. AN upper magnetic shield
75
made of a magnetic material is disposed on the insulating layers
78
through an upper gap film
74
made of a non-magnetic conductive material. The upper gap film
74
serves also as an electrode film and is connected to the GMR element
73
through an opening (width W) defined between the right and left insulating layers
78
.
The lower magnetic shield
71
and the lower gap film
72
constitute a lower electrode, and the upper magnetic shield
75
and the upper gap film
74
constitute an upper electrode. Through these lower and upper electrodes, a sense current in the direction perpendicular to the film plane of the laminated layer film can flow to the GMR element
73
. Moreover, the hard magnetic film
77
can stabilize the GMR element
73
magnetically.
In the arrangement shown in
FIG. 2
, the respective layers can function as follows:
The lower magnetic shield
71
and the upper magnetic shield
75
can function to restrict a signal magnetic field from being entered into the GMR element
73
in order to increase a recording density in the axis direction of a recording medium (not shown). As the materials of the lower magnetic shield
71
and the upper magnetic shield
75
, there may be used NiFe, FeN and so forth.
The lower gap film
72
and the upper gap film
74
made of the non-magnetic conductive materials can function to magnetically separate the lower magnetic shield
71
, the upper magnetic shield
75
and the GMR element
73
from each other. The GMR head which includes the CIP type GMR element needs an insulating material such as an alumina as the gap film in order to insulate the magnetic shield and the GMR element from each other. On the other hand, the GMR head which includes the CPP type GMR element uses the conductive materials as the lower and upper magnetic gap films
72
and
74
in order to enable the sense current to flow through the lower and upper magnetic gap films
72
and
74
to the GMR element
73
. Au, Cu, Ta and so forth, for example, may be used as the conductive materials of the lower and upper magnetic gap films
72
and
74
.
When the signal magnetic field entered into the GMR element
73
from the recording medium (not shown) is changed, an electric resistance of the GMR element
73
also is changed in response to the change of the signal magnetic field. At that very time, when the current (sense current) is flowing through the GMR element
73
, it is possible to detect the change of the electric resistance as an output.
The insulating films
76
between the GMR element
73
and the hard magnetic film
77
should preferably be made as thin as possible from the sta
Makino Eiji
Matsuzono Atsushi
Ohkawara Shigehisa
Ono Hiroaki
Terada Shoji
Evans Jefferson
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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