Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-05-11
2002-12-03
Ometz, David L. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S123090
Reexamination Certificate
active
06490128
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film device having an electrically conductive thin-film, such as a coil layer, and an electrical conductor, such as a lead layer and a bump, which are in contact with the surface of the electrically conductive thin-film, and more particularly, relates to a thin-film device in which contact failures can be reduced and stability of direct current resistance can be improved by improving cohesion and electrical conduction between the electrically conductive thin-film and the electrical conductor, and relates to a manufacturing method therefor.
2. Description of the Related Art
FIG. 10
is a cross-sectional view of a conventional magnetoresistive (MR)/inductive hybrid head. In a reading MR thin-film magnetic head h
1
of the MR/inductive hybrid head, an alumina undercoat film
1
a
is formed on a slider
1
composed of alumina-titanium-carbide, and a laminated structure, which is composed of a lower shield layer
2
, a lower gap layer
3
, an MR element layer
4
, an electrode layer
5
, an upper gap layer
6
, and an upper shield layer
7
, is formed on the alumina undercoat layer
1
a.
A recording inductive head h
2
provided on the reading MR thin-film magnetic head h
1
is a laminated structure composed of a lower core layer
7
which is also used as the upper shield layer
7
, a gap layer
8
a
, an insulating layer
8
b
, a coil layer
9
, an insulating layer
10
, an upper core layer
11
, a lead layer
12
, and an insulating layer
13
. A front end of the gap layer
8
a
, which is disposed between the lower core layer
7
and the upper core layer
11
and opposes a recording medium, forms a magnetic gap G.
The lead layer
12
is in contact with an electrode for an external connection composed of a bump
15
and a bonding pad
16
at the other edge of the lead layer
12
, which is opposite to the edge thereof in electrical contact with a central edge
9
a
of the coil layer
9
, via an elevating layer
14
made of the same material as was used for the coil layer
9
.
FIG. 11
is an enlarged partial cross-sectional view of a contact area between the coil layer
9
and the lead layer
12
of the inductive head h
2
for recording data on a magnetic recording medium.
The coil layer
9
as an electrically conductive thin-film is composed of a copper layer
9
c
as an electrically conductive material layer formed by flame plating above the insulating layer
8
b
, which is provided on the gap layer
8
a
of the inductive head h
2
, via a coil base layer
9
b
composed of titanium and copper. The coil layer
9
is flatly coiled on the insulating layer
8
b
. The lead layer
12
, which is an electrical conductor, is formed above the coil layer
9
via the insulating layer
10
. The lead layer
12
is formed by plating using permalloy. The coil layer
9
and the lead layer
12
are in electrical contact with each other at the central edge
9
a
of the coil layer
9
.
FIGS. 12
to
17
are cross-sectional views of the inductive head h
2
of the MR/inductive hybrid thin-film magnetic head shown in
FIG. 10
in a manufacturing process therefor.
FIG. 12
shows a state of the insulating layer
8
b
composed of a hard-baked resist formed on the gap layer
8
a
composed of Al
2
O
3
, SiO
2
, or the like provided on the lower core layer
7
.
FIG. 13
shows a state of the coil base layer
9
b
in a laminated structure composed of titanium and copper formed on the insulating layer
8
b
by a vacuum film deposition process, such as sputtering, and the copper layer
9
c
of the electrically conductive material layer formed on the coil base layer
9
b
by flame plating. The copper layer
9
c
is flatly formed in the form of a coil on the coil base layer
9
b.
In addition, the coil base layer
9
b
exposed by the copper layer
9
c
is removed by dry-etching such as by ion-milling using argon ions, and as a result, the coil layer
9
composed of the coil base layer
9
b
and the copper layer
9
c
is formed as shown in FIG.
14
.
Next, as shown in
FIG. 15
, the insulating layer
10
is formed on the coil layer
9
. In this step, an opening
10
a
is formed in the insulating layer
10
at the position at which the central edge
9
a
of the coil layer
9
is present.
As shown in
FIG. 16
, a plating base layer
17
(not shown in
FIGS. 10 and 11
) to form the upper core layer
11
and the lead layer
12
by plating is formed on the insulating layer
10
by sputtering. The plating base layer
17
is made of, similarly to the upper core layer
11
and the lead layer
12
, permalloy or the like. In this step, the surface of the central edge
9
a
of the coil layer
9
in the opening
10
a
is covered with the plating base layer
17
.
In addition, the upper core layer
11
and the lead layer
12
are simultaneously formed on the plating base layer
17
by plating using permalloy, and the surfaces of the upper core layer
11
and the lead layer
12
are covered with the insulating layer
13
. A front end of the gap layer
8
a
, which is disposed between the lower core layer
7
and the upper core layer
11
and opposes a recording medium, forms the magnetic gap G.
FIG. 17
is a cross-sectional view of the completed inductive head h
2
in a laminated structure.
In the conventional inductive head h
2
described above, in the step for removing the coil base layer
9
b
exposed by the copper layer
9
c
, as shown in
FIG. 13
, by ion-milling or the like, the upper surface of the copper layer
9
c
is polished, as is the coil base layer
9
b
. When the upper surface of the copper layer
9
c
is polished, direct current resistance of the coil layer
9
varies, and hence, there is a problem in that product characteristics of the manufactured inductive head h
2
are degraded. In addition, when ion-milling is performed, bombardment by argon ions on the upper surface of the copper layer
9
c
may cause damage, such as residual stress in the copper layer
9
c
, and hence, there is also a problem in that direct current resistance of the coil layer
9
varies.
Furthermore, between the formations of the coil layer
9
and the insulating layer
10
, the coil layer
9
is exposed to the air in some cases as shown in FIG.
14
. In addition, the central edge
9
a
of the coil layer
9
is exposed in the opening
10
a
in the insulating layer
10
in the state of the insulating layer
10
formed as shown in
FIG. 15
, and accordingly, the central edge
9
a
of the coil layer
9
may be exposed to the air until the plating base layer
17
is formed so as to cover the upper surface of the central edge
9
a
in the opening
10
a
of the insulating layer
10
.
When the coil layer
9
is exposed to the air, the surface of the coil layer
9
, which is an electrically conductive thin-film, is oxidized, and the oxide layer forms. In particular, when the insulating layer
10
is heat-cured to planarize the surface thereof, the central edge
9
a
of the coil layer
9
in the opening
10
a
is exposed to the air, and hence, is susceptible to forced oxidation.
In the case in which the surface of the coil layer
9
is oxidized, i.e., in which the oxide layer forms thereon, cohesion between the coil layer
9
and the insulating layer
10
formed thereon, and between the coil layer and the lead layer
12
are degraded, and separation thereof readily occur. In particular, in the case in which the central edge
9
a
of the coil layer
9
, which is in contact with the lead layer
12
, is oxidized, degradation in electrical conduction as well as the degradation in the cohesion with the lead layer
12
occurs. Consequently, the direct current resistance of the inductive head h
2
becomes unstable and recording characteristics thereof are degraded.
When the oxide layer forms on the coil layer
9
, there are methods for removing the oxide layer by dry etching, such as by ion-milling. However, the thickness of the oxide layer formed on the surface of the coil layer
9
, that is, the copper layer
9
c
, varies in accordance with the conditions when the
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ometz David L.
LandOfFree
Thin-film device with improved cohesion and electrical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin-film device with improved cohesion and electrical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin-film device with improved cohesion and electrical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2988476