Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-07-05
2003-07-22
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06597534
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thin-film magnetic heads for writing used in floating magnetic heads. In particular, the present invention relates to a thin-film magnetic head which is suitable for narrower tracks and which can suppress write fringing. The present invention also relates to a method for making the thin-film magnetic head.
2. Description of the Related Art
FIG. 13
is a partial front view of a conventional thin-film magnetic head viewed from a face opposing a recording medium, the air bearing surface (ABS). This thin-film magnetic head is an inductive write head. A MR read head may be provided under this inductive head.
The inductive head has a lower core layer
1
and an insulating layer
9
formed of an insulating material such as SiO
2
on the lower core layer
1
. The insulating layer
9
has a groove
9
a
. A lower magnetic pole layer
3
, a magnetic gap layer
4
, an upper magnetic pole layer
5
, and an upper core layer
6
are formed, in that order, in the groove
9
a
. The lower magnetic pole layer
3
is magnetically coupled with the lower core layer
1
, whereas the upper magnetic pole layer
5
is magnetically coupled with the upper core layer
6
.
The groove
9
a
has a base section having a track width T
w
and an upper section having sloping faces
9
b
which gradually converge from a surface
9
c
of the insulating layer
9
in the track width direction. The upper core layer
6
is formed over the upper magnetic pole layer
5
and the sloping faces
9
b.
FIGS. 14
to
16
show steps for making the thin-film magnetic head shown in FIG.
13
. With reference to
FIG. 14
, the insulating layer
9
is formed on the lower core layer
1
and then a resist layer
7
is formed thereon. The resist layer
7
is exposed and developed to form a predetermined gap
7
a
by patterning. The gap
7
a
is formed in the perpendicular direction (in the Z direction in the drawing) to the lower core layer
1
and has a constant width T
w
. The exposed portion of the insulating layer
9
is etched by a reactive ion etching (RIE) process to form the groove
9
a
having the width T
w
. Thus, the track width T
w
is defined by the width of the gap
7
a
formed in the resist layer
7
.
With reference to
FIG. 15
, the resist layer
7
is removed and then a resist layer
8
having a gap
8
a
which is larger than the groove
9
a
is formed on the groove
9
a
by a patterning process. The resist layer
8
has a thickness H
1
. Since the thickness H
1
of the resist layer
8
is larger than the width T
w
of the groove
9
a
in the insulating layer
9
, the surfaces
9
c
of the insulating layer
9
are partially exposed in the gap
8
a.
With reference to
FIG. 16
, the surfaces
9
c
of the insulating layer
9
are obliquely etched by ion milling to form the sloping faces
9
b.
In the thin-film magnetic head which is formed by the steps shown in
FIGS. 14
to
16
and which is shown in
FIG. 13
, the track width T
w
can be formed to be 1.0 &mgr;m or less. Moreover, the upper core layer
6
is formed on the sloping faces
9
b
in the groove
9
a
of the insulating layer
9
. Thus, the upper core layer
6
is properly distant from the lower magnetic pole layer
3
which is magnetically coupled with the lower core layer
1
so that write fringing is effectively prevented.
This conventional thin-film magnetic head, however, is suitable for future narrower track widths. The width (resolution) of the gap
7
a
formed by the patterning step shown in
FIG. 14
significantly depends on the wavelength used in the exposure and developing process. The shorter the wavelength, the higher the resolution. Since the resolution is limited, the gap
7
a
cannot have a width which is smaller than the resolution limit.
As described in the patterning step shown in
FIG. 14
, the width of the groove
9
a
defining the track width T
w
is substantially the same as the width of the gap
7
a
formed in the resist layer
7
by patterning. In the method for defining the track width T
w
, which transfers the gap
7
a
to the groove
9
a
using the RIE process, a track width T
w
which is smaller than the width of the resist layer
7
, which is limited by the resolution, cannot be formed.
In the ion milling step shown in
FIG. 16
, the incident angles &thgr;
1
and &thgr;
2
of ions entering from the right and left sides, respectively, in the drawing are different from each other due to an uneven ion distribution. As a result, the tilted angles of the sloping faces
9
b
are different between the left and the right, and these sloping faces
9
b
are not symmetrically arranged.
As the track width T
w
is decreased, the imbalance between the tilted angles of the sloping faces
9
b
is significant when the resist layer
8
on the insulating layer
9
is unevenly distributed or when the resist layer
8
has a large thickness H
1
.
Referring to
FIG. 13
, when the tilted angles of the right and left sloping faces
9
b
are different from each other, a fringing magnetic field will be easily generated between the upper core layer
6
on the sloping faces
9
b
and, for example, the lower magnetic pole layer
3
magnetically coupled with the lower core layer
1
. As a result, write fringing cannot be effectively prevented.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thin-film magnetic head which has a track width T
w
smaller than the resolution of a resist and which effectively prevents write fringing.
It is another object of the present invention to provide a method for making the thin-film magnetic head.
According to an aspect of the present invention, a thin-film magnetic head includes: a lower core layer, the lower core layer optionally having a lower magnetic pole layer thereon; an upper core layer, the upper core layer optionally having an upper magnetic pole layer thereunder; at least one insulating layer disposed between the lower core layer and the upper core layer, the insulating layer having a groove for defining a track width; at least one of the lower magnetic pole layer and the upper magnetic pole layer being provided in the groove; and a magnetic gap layer provided between the lower core layer and the upper core layer. The insulating layer includes at least one primary insulating layer lying at the lower core layer side and at least one auxiliary insulating layer formed on the primary insulating layer, the groove is formed at least in the primary insulating layer, the auxiliary insulating layer has sloping faces gradually diverging in the track width direction from both top edges of the groove to the surfaces of the auxiliary insulating layer, and the upper core layer is formed on the sloping faces.
In the present invention, the primary insulating layer is formed on the lower core layer and the auxiliary insulating layer is formed thereon. The auxiliary insulating layer has the groove for defining the track width T
w
. The track width T
w
is smaller than the resolution of a resist, and is preferably not more than 0.7 &mgr;m, more preferably not more than 0.5 &mgr;m, and most preferably not more than 0.3 &mgr;m.
Moreover, the auxiliary insulating layer has sloping faces which gradually diverge in the track width direction from both top edges of the groove to the surfaces of the auxiliary insulating layer. The upper core layer, which may include the upper magnetic pole layer, is formed on the sloping faces. Since the sloping faces are symmetrically formed, write fringing is effectively prevented.
The sloping faces may be formed by etching the auxiliary insulating layer or by forming the auxiliary insulating layer by a sputtering process.
Preferably, the etching rate of the primary insulating layer in reactive ion etching is higher than the etching rate of the auxiliary insulating layer.
Preferably, the primary insulating layer comprises at least one insulating material selected from the group consisting of Al
2
O
3
, SiO
2
, Ta
2
O
5
. Preferably TiO, AlN, AlSiN, TiN, SiN, NiO, WO, WO
3
, BN, CrN, and SiO
Brinks Hofer Gilson & Lione
Klimowicz William
Nguyen Dzung C.
LandOfFree
Thin-film magnetic head suitable for narrower tracks and... 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 magnetic head suitable for narrower tracks and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin-film magnetic head suitable for narrower tracks and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3049975