Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-01-05
2004-06-29
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
C360S317000
Reexamination Certificate
active
06757133
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head including an inductive head for writing, or a combined thin film magnetic head in which an inductive head for writing and a magnetoresistive (MR) head for reading are laminated. More particularly, the invention relates to a thin film magnetic head in which a coil layer can be properly formed and inductance can be reduced at the same time.
2. Description of the Related Art
FIG. 10
is a longitudinal sectional view of a conventional thin film magnetic head, and the left end of the thin film magnetic head in the drawing corresponds to an air bearing surface (ABS).
This thin film magnetic head is provided on the trailing edge of a slider of a floating-type magnetic head which faces a recording medium such as a hard disk, and is a combined thin film magnetic head including an MR head which uses magnetoresistance for reading and an inductive head for writing.
A lower shielding layer
1
is composed of a magnetic material such as an NiFe alloy (permalloy), and a lower gap layer
2
is formed on the lower shielding layer
1
. A magnetoresistive element
3
is formed on the lower gap layer
2
. The magnetoresistive element
3
includes a multilayer film
4
composed of a spin-valve element (one type of GMR element) or the like that exhibits magnetoresistance, a pair of hard bias layers (not shown in the drawing) formed on both sides of the multilayer film
4
, and an electrode layer (not shown in the drawing) for applying a sensing current to the multilayer film
4
.
An upper shielding layer
8
composed of a magnetic material such as an NiFe alloy is further formed on the magnetoresistive element
3
with a nonmagnetic upper gap layer
7
therebetween. As described above, the thin film magnetic head shown in
FIG. 10
is a combined thin film magnetic head in which an MR head and an inductive head are laminated, and the upper shielding layer
8
also serves as a lower core layer for the inductive head. Hereinafter, the layer represented by numeral
8
is referred to as a lower core layer.
A gap layer
10
composed of a nonmagnetic material, such as Al
2
O
3
(alumina) or SiO
2
, is formed on the lower core layer
8
. An insulating layer
11
composed of a resist material or other organic materials is further formed on the gap layer
10
.
A coil layer
12
, composed of a conductive material having low electrical resistance, such as Cu, is spirally formed on the insulating layer
11
. The coil layer
12
is formed so as to go around a base
15
b
of an upper core layer
15
, which will be described below.
As shown in
FIG. 10
, the coil layer
12
is covered by an insulating layer
14
composed of an organic material or the like. A hole is made in the gap layer
10
and the insulating layer
14
formed on the lower core layer
8
, and the base
15
b
of the upper core layer
15
is formed through the hole, thus magnetically coupling the upper core layer
15
and the lower core layer
8
.
The upper core layer
15
is formed on the insulating layer
14
in the direction of the ABS (toward the left in the drawing), and a tip
15
a
of the upper core layer
15
is joined to the lower core layer
8
with the gap layer
10
therebetween at the section facing a recording medium to form a magnetic gap having a gap length Gl.
As shown in
FIG. 10
, above a coil center
12
a
of the coil layer
12
, which is formed at the rear of the lower core layer
8
(on the right side in the drawing), a hole is made in the insulating layer
14
, and a coil lead layer
18
is formed on the coil center
12
a
through the hole.
For example, the coil lead layer
18
is composed of the same material as that for the upper core layer
15
, and is formed simultaneously with the upper core layer
15
.
In the inductive head for writing, when a recording current is applied to the coil layer
12
, a recording magnetic field is induced in the lower core layer
8
and the upper core layer
15
, and a magnetic signal is recorded onto a recording medium such as a hard disk by means of a leakage magnetic field from the magnetic gap between the lower core layer
8
and the tip
15
a
of the upper core layer
15
.
However, in the structure of the thin film magnetic head shown in
FIG. 10
, a sharp step is produced at the rear of the lower core layer
8
(on the right side in the drawing), and the coil layer
12
must be formed on the insulating layer
11
having the step. If the width of the lower core layer
8
(in the track width direction; perpendicularly with respect to the drawing) is smaller than the width of the coil layer
12
, a portion of the coil layer
12
in the width direction must be formed on the insulating layer
11
having the step beneath which the lower core layer
8
is not formed.
That is, in the thin film magnetic head shown in
FIG. 10
, since the lower core layer
8
is not formed entirely beneath the insulating layer
11
on which the coil layer
12
is to be formed, the coil layer
12
extending beyond the lower core layer
8
must be formed on the insulating layer
11
having the step. When the coil layer
12
is formed on such an insulating layer
11
having the step, it is not possible to pattern the coil layer
12
in a proper shape due to inconsistent focus when a resist layer is exposed during the formation of the coil layer
12
.
Additionally, by increasing the pitch of the coil layer
12
, patterning of the coil layer
12
can be performed properly to a certain extent. However, if the pitch of the coil layer
12
is increased, the length of the upper core layer
15
form the tip
15
a
to the base
15
b
must be increased, and thereby the length of a magnetic path made from the upper core layer
15
through the lower core layer
8
is increased, resulting in an increase in inductance.
FIG. 11
is a partial perspective view of a thin film magnetic head which is improved in order to overcome the problems described above, and
FIG. 12
is a longitudinal sectional view of the thin film magnetic head shown in FIG.
11
.
As shown in
FIG. 11
, a lower core layer
16
is formed larger than a coil layer
12
. Thus, there is no step in an insulating layer
11
in the region in which the coil layer
12
is to be formed (refer to FIG.
12
), and the coil layer
12
can be accurately patterned on a planarized surface (the insulating layer
11
).
However, as shown in
FIG. 11
, if the size of the lower core layer
16
is increased, inductance increases, and in particular, in the coming age of high frequency and high recording density, there is a growing need for a reduction of inductance.
As shown in
FIG. 12
, the lower core layer
16
has a step
16
a
, following the steps in the individual layers formed thereunder, and it is not possible to form the coil layer
12
on a completely planarized surface (insulating layer
11
). When there is such a step
16
a
, the pitch of the coil layer
12
must be increased so that the patterning accuracy in the formation of the coil layer
12
is improved, and in accordance with the increase in the pitch of the coil layer
12
, the length of an upper core layer
15
must be increased, and thus the length of the magnetic path is increased, resulting in a further increase in inductance.
As described above, in the conventional thin film magnetic heads, the formation of a coil layer on a planarized surface without a step and a reduction in inductance are incompatible.
SUMMARY OF THE INVENTION
The present invention has been achieved to overcome the disadvantages associated with the conventional thin film magnetic heads. It is an object of the present invention to provide a thin film magnetic head in which a planarizing layer is formed in the periphery of a lower core layer so that a coil layer is formed properly and inductance is reduced at the same time, and to provide a method of producing the same.
In accordance with the present invention, a thin film magnetic head includes a lower core layer composed of a magnetic material; an upper core layer composed of a
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Heinz A. J.
LandOfFree
Thin Film magnetic head 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, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin Film magnetic head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3308313