Coating processes – Magnetic base or coating – Magnetic coating
Reexamination Certificate
2002-10-24
2003-12-30
Pianalto, Bernard (Department: 1762)
Coating processes
Magnetic base or coating
Magnetic coating
C427S131000, C427S259000, C427S264000, C427S265000, C427S272000, C427S282000, C427S331000, C427S402000
Reexamination Certificate
active
06669983
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a manufacturing method of a thin-film magnetic head with a magnetoresistive effect (MR) element for detecting magnetic intensity in a magnetic recording medium and for outputting a read signal.
DESCRIPTION OF THE RELATED ART
Recently, in order to satisfy the demand for higher recording density and downsizing in a hard disk drive (HDD) apparatus, higher sensitivity and larger output of a thin-film magnetic head are required. Thus, improvement in characteristics of a general giant magnetoresistive effect (GMR) head with a GMR element which is current-manufactured are now strenuously proceeding and also development of a tunnel magnetoresistive effect (TMR) head with a TMR element is energetically performed.
Because of the difference in flowing directions of their sense currents, structures of these TMR head and general GMR head differ from each other. One head structure in which a sense current flows in a direction parallel with surfaces of laminated layers as in the general GMR head is called as a current in plane (CIP) structure, whereas the other head structure in which a sense current flows in a direction perpendicular to surfaces of laminated layers as in the TMR head is called as a current perpendicular to plane (CPP) structure.
In recent years, CPP-GMR heads not CIP-GMR heads are being developed. For example, Japanese patent publication No. 05275769A discloses such a CPP-GMR head. Japanese patent publication Nos. 04360009A, 05090026A and 09129445A disclose CPP-GMR heads having anti-ferromagnetic coupling magnetic multi-layered films consisting of a plurality of magnetic layers stuck with each other via nonmagnetic layers (Cu, Ag, Au or others).
Also, provided are CPP-GMR heads with spin valve magnetic multi-layered films including such as specular type magnetic multi-layered films or dual-spin valve type magnetic multi-layered films.
Conventionally a lift-off method or a contact-hole method has been used for fabricating such CPP-GMR heads or TMR heads.
FIGS. 1
a
to
1
f
show sectional views illustrating a part of a conventional fabrication process of a CPP-GMR head by the lift-off method.
First, as shown in
FIG. 1
a,
a lower electrode film
11
and a MR multi-layered film
12
′ are sequentially deposited on an insulation film
10
formed on a substrate (not shown).
Then, a photo-resist pattern
13
of a two-layers structure is formed thereon as shown in
FIG. 1
b,
and the MR multi-layered film
12
′ is patterned by ion milling to obtain a MR multi-layered structure
12
as shown in
FIG. 1
c.
Then, an insulation film
14
′ is deposited thereon as shown in
FIG. 1
d,
and the photo-resist pattern
13
is removed or lifted off to obtain a patterned insulation film
14
as shown in
FIG. 1
e.
Thereafter, an upper electrode film
15
is deposited thereon as shown in
FIG. 1
f.
In executing this lift-off method, it is necessary that no insulation film
14
′ deposited on the side surface of a stepped portion of the photo-resist pattern
13
is bridged over the stepped portion. Thus, in general, a T-shaped two-layers structure photo-resist pattern with an undercut is used in order to improve the lift-off performance.
However, if the amount or depth of the undercut of the photo-resist pattern
13
is small, the insulation film may be deposited on a side surface of a base
13
a
of the two-layers structure photo-resist pattern
13
causing occurrence of unnecessary burr around the removed photo-resist pattern. Contrary to this, if the undercut amount is large, a burr will be prevented from occurrence but the width of the base
13
a
of the photo-resist pattern
13
will become extremely narrow causing lost of the pattern.
Also, according to the lift-off method, a part of the insulation film
14
intruded into the undercut portion may be remained to overlap with a top surface of the MR multi-layered structure
12
as shown in
FIG. 1
e.
Such overlapped insulation film causes ambiguity in a track width and limits fine micromachining of the track width. Since the length of each overlapped insulation film on the MR multi-layered structure is about 100 nm, it is impossible to fabricate by the lift-off method a recent TMR element or GMR element with an extremely narrow track width of 200 nm or less, such as around 100 nm.
In typical MR multi-layered structure of the TMR or GMR element, a free layer is located at a middle of the MR multi-layered structure and its width determines the track width. Therefore, if the MR multi-layered structure is formed by ion milling using the conventional photo-resist mask, the bottom of the MR multi-layered structure will widen causing an effective track width to increase. It is desired that the side surface of the MR multi-layered structure is perpendicular to the substrate surface and this may be implemented by an ion milling method using a hard mask or by a reactive ion etching (RIE) method. However, in principal, such methods cannot be utilized in the lift-off method.
FIGS. 2
a
to
2
g
show sectional views illustrating a part of a conventional fabrication process of a CPP-GMR head by the contact-hole method.
First, as shown in
FIG. 2
a,
a lower electrode film
21
and a MR multi-layered film
22
′ are sequentially deposited on an insulation film
20
formed on a substrate (not shown).
Then, a photo-resist pattern
23
is formed thereon as shown in
FIG. 2
b,
and the MR multi-layered film
22
′ is patterned by ion milling to obtain a MR multi-layered structure
22
as shown in
FIG. 2
c.
Then, after the photo-resist pattern
23
is removed, an insulation film
24
′ is deposited thereon as shown in
FIG. 2
d.
Then, as shown in
FIG. 2
e,
a photo-resist pattern
26
with an opening
26
a
located at a contact hole is formed on the insulation film
24
′.
Then, as shown in
FIG. 2
f,
the insulation film
24
′ is patterned by ion milling to obtain an insulation film
24
provided with a contact hole
24
a
on the MR multi-layered structure
22
, and thereafter the photo-resist pattern
26
is removed.
After that, an upper electrode film
25
is deposited thereon as shown in
FIG. 2
g.
According to this contact-hole method, however, since two photo processes with respect to the photo-resist patterns are executed, the amount of the overlap due to a deviation between both the alignments will become about 30 nm. Such overlap amount of the insulation film cannot be negligible as well as in case of the lift-off method.
As aforementioned, according to the conventional manufacturing method, it is quite difficult to fabricate a GMR head with the CPP structure or a TMR head having a very narrow track width of 200 nm or less, and therefore it has been demanded to provide a novel fabrication method capable of fabricating such CPP-GMR head or TMR head with the extremely narrow track width.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a manufacturing method of a thin-film magnetic head with an MR element, whereby an MR element with a structure in which a sense current flows in a direction perpendicular to surfaces of laminated layers and with a track width of 200 nm or less can be easily manufactured.
According to the present invention, a manufacturing method of a thin-film magnetic head provided with an MR element includes a step of forming an MR multi-layered structure in which a current flows in a direction perpendicular to surfaces of layers of the MR multi-layered structure, on a lower electrode film, a step of depositing an insulation film on the formed MR multi-layered structure and the lower electrode film, a step of flattening the deposited insulation film until at least upper surface of the MR multi-layered structure is exposed, and a step of forming an upper electrode film on the flattened insulation film and the MR multi-layered structure.
Without using a lift-off method, an insulation film is deposited on the MR multi-layered structure and the lower electrode film, and then this insulation
Kagami Takeo
Kuwashima Tetsuya
Ohta Naoki
Burns Doane Swecker & Mathis L.L.P.
Pianalto Bernard
TDK Corporation
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