Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
2002-01-31
2004-08-03
Mills, Gregory (Department: 1763)
Etching a substrate: processes
Forming or treating article containing magnetically...
C029S603070
Reexamination Certificate
active
06770210
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-26028, filed on Feb. 1, 2001; the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a magnetoresistance effect element and a method for producing the same.
2. Description of Related Art
In recent years, the density of information recorded in a magnetic recording medium has been increased. In HDD (Hard Disk Drive) units, a system having a high packing density of 10 Gbpsi (Gigabit per square inch) has been put to practical use, and a system having a higher packing density has been required. As a countermeasure thereto, it is important to form a narrow track having a width of 1 &mgr;m in a magnetic head. Also in a recording and/or reproducing thin-film magnetic head, various proposals for structure have been made in order to achieve a narrow track. However, it is said that a magnetic packing density capable of being applied to the structure of a conventionally proposed recording and/or reproducing thin-film magnetic head is limited to about 100 to 200 Gbpsi. In order to further increase the magnetic packing density, it is required to provide a magnetic gap having a size of 0.1 &mgr;m or less and a high reproducing output. However, it is very difficult to realize such a magnetic gap and a high reproducing output in a conventionally proposed recording and/or reproducing thin-film magnetic head.
Therefore, in order to solve these problems, a horizontal thin-film magnetic head and a CPP (Current Perpendicular to the Plane) type magnetoresistance effect film material having a large magnetoresistance effect have been proposed in Japanese Patent Laid-Open Nos. 11-120509 and 11-25433 and Outline of 24-th Lecture of Japan Applied Magnetism Institution (2000), page 427.
FIG. 5
is a schematic diagram most simply showing a CPP type magnetoresistance effect element (which will be also hereinafter referred to as a CPP element). That is, this CPP element
40
has a structure wherein a bottom electrode
41
and a top electrode
45
are formed on the top and bottom of a CPP type magnetoresistance effect film
43
, an insulator (not shown) being formed around the bottom and top electrodes
41
and
45
. Because of such a structure, a reproducing current I caused to flow through the bottom electrode
41
is separated into a current I
1
flowing through the CPP type magnetoresistance effect film
43
and a leakage current I
2
flowing between the top and bottom electrodes
41
and
45
to flow into the top electrode
45
. At this time, with respect to the output of the CPP type magnetoresistance effect film
43
, only a variation in resistance due to the current I
1
is detected as a variation in voltage.
In the thin-film magnetic head using the CPP element
40
wherein a current is applied in a direction perpendicular to the plane of the film, the thickness of the insulator decreases as the thickness of the reproducing element (CPP element) decreases. In accordance therewith, the distance between the electrodes
41
and
45
for sandwiching the reproducing element therebetween decreases, and the possibility of increasing a leakage current flowing through the insulator other than a current flowing through the reproducing element increases. Therefore, in order to solve such a problem, it is required to develop a CPP type magnetoresistance effect film material capable of obtaining a high reproducing output with a small current and an insulating material having a high withstand voltage. However, it is not easy to achieve the purposes therefor.
FIG. 6
shows the cross-sectional structure of an actual reproducing magnetic head when the CPP element
40
is applied to the head. In the construction of the reproducing magnetic head, magnetization information is sucked up from a medium (not shown) by a reproducing magnetic yoke
48
to be propagated to the CPP element
40
, and the resistance changes by the change in direction of magnetization at that time. In
FIG. 6
, a magnetization fixing layer
47
is formed on the side portion of the CPP type magnetoresistance effect film
43
. Also in this case, in
FIG. 6
, when a reproducing current is caused to flow, the direction of magnetization of the CPP element
40
fluctuates by a magnetic field due to current from a corner portion of the top electrode
45
, so that it is not possible to obtain a high reproducing output.
On the other hand, as a magnetoresistance effect element using the same principle as that of the CPP element, there is a TMR (Tunneling Magneto-Resistance) element. In the case of the TMR element, an insulator of Al
2
O
3
or the like is used as a junction. Since this insulator has a very small thickness of about 1 nm, it is not required to cause a sense current, which flows through the TMR element, to be larger than that of the CPP element, and it is not required to increase the withstand voltage of a surrounding insulator in the TMR element.
On the other hand, it is required to cause a large sense current to flow through the CPP element
40
in order to obtain a high reproducing output. In this case, the magnetic field due to sense current is very large to disturb the direction of magnetization of the magnetization fixing layer
47
and to form the CPP type magnetoresistance effect film
43
. Since the direction of magnetization of a magneto-sensitive layer having magnetization disperses, there is a problem in that the detection sensitivity greatly decreases. As an example, the relationship between the sense currents of a TMC element and CPP element and the magnetic fields due to the currents is shown in FIG.
7
. As shown in
FIG. 7
, in order to obtain a necessary and sufficient reproducing output, the sense current of the CPP element must be about ten times as large as that of the TMR element. In accordance therewith, the magnetic field due to current, which is applied to the CPP element and which is produced in the vicinity of the CPP element is a very large magnetic field of 50 to 1000 times as large as that of the TMR element.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a magnetoresistance effect element which is capable of causing a large sense current to flow between electrodes and which has a smaller dispersion in direction of magnetization of a CPP element based on a magnetic field due to the sense current and has a lager reproducing output, and a method for producing the same.
In order to accomplish the aforementioned and other objects, according to a first aspect of the present invention, there is provided a method for producing a magnetoresistance effect element comprising: after forming a first electrode, forming a magnetoresistance effect film on the first electrode; applying a self-condensing organic resist on the magnetoresistance effect film, and thereafter, causing the organic resist to be droplets; subsequently, forming an insulating film thereon, and thereafter, removing the organic resist to form a groove portion in the insulating film to expose the top surface of the magnetoresistance effect film; and filling the groove portion with an electrode material to form a second electrode.
According to such a method for producing magnetoresistance effect according to the first aspect of the present invention, the groove portion formed in the insulating film leaves the magnetoresistance effect film as approaching the periphery of the magnetoresistance effect film, so that the distance between the first and second electrodes increases as approaching the periphery of the magnetoresistance effect film. Thus, even if a large current is caused to flow between the first and second electrodes, it is possible to prevent the direction of magnetization of a magnetization fixing film, which is formed on the side portion of the magnetoresistance effect film, from being disturbed by a magn
Hara Michiko
Hashimoto Susumu
Ohsawa Yuichi
Culbert Roberts
Mills Gregory
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