Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-05-25
2003-02-04
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06515824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic recording head which is used for, for example, a floating magnetic head, which is adaptable to track narrowing, and which can appropriately suppress the occurrence of write fringing and magnetic flux saturation, and a method of manufacturing the thin film magnetic head.
2. Description of the Related Art
A thin film magnetic head mounted to a hard disk or the like comprises, for example, an inductive head for writing signals on a recording medium such as a hard disk, and a MR head for reading signals from the recording medium.
The inductive head generally comprises upper and lower core layers made of a magnetic material, and a coil layer for inducing a recording magnetic field in the core layers so that a magnetic signal is recorded on a recording medium by a leakage magnetic field between the core layers.
In recent years, the track width Tw of the inductive head has been decreased to comply with the requirement for narrowing a track accompanying an increase in recording density. The track width Tw is determined by the width dimension at the end of the upper core layer exposed in a surface (ABS) facing the recording medium.
The upper core layer is conventionally formed by, for example, a so-called frame plating process. In this frame plating process, a resist layer is patterned in the shape of the upper core layer, and a magnetic material used as a material for the upper core layer is plated in the pattern. Then, the resist layer is removed to complete the upper core layer having an end with the track width Tw.
However, the frame plating process is very difficult to pattern the resist layer with the small track width Tw because of the resolution limit of exposure in pattering the resist layer. This problem will become significant with further increases in recording density in future.
U.S. Pat. No. 5,652,687 discloses the structure of an inductive head formed by a process different from the above-described frame plating process, and a method of producing the inductive head.
FIG. 10
shows the frame plating process disclosed in U.S. Pat. No. 5,652,687.
In
FIG. 10
, reference numeral
102
denotes a lower pole layer (lower core layer) on which a notch structure
120
made of silicon dioxide or the like is formed.
FIG. 11
is a perspective view showing the shape of the notch structure
120
, a trench
148
being formed in the notch structure
120
. A pole tip layer P
1
(T), a gap layer G, and a pole tip layer P
2
(T) are laminated in the trench
148
.
Furthermore, the pole tip
108
of an upper pole layer (upper core layer)
104
, which has a width dimension larger then the width dimension of the pole tip layer P
2
(T), is formed on the pole tip layer P
2
(T) and the notch structure
120
.
This publication discloses that the production process can provide a thin film magnetic write head having a sub-micron track width. The publication also discloses that as shown in
FIG. 10
, the pole tip
108
having a width dimension larger then the width dimension of the pole tip layer P
2
(T) is formed on the pole tip layer P
2
(T), and magnetic saturation accompanying track narrowing can thus be prevented by the formation of the pole tip
108
.
The inductive head shown in
FIG. 10
has the function to write signals on the recording medium by means of a leakage magnetic field produced between the core layers. However, since the pole tip
108
is formed at right angles on the upper edge of the pole tip layer P
2
(T), the leakage magnetic field reaches from the pole tip
108
to the pole tip layer PI (T), as shown by broken lines in FIG.
10
. As a result, write fringing (writing blot) which occurs on both sides of the track width Tw is easily formed on the recording medium.
The occurrence of write fringing makes it impossible to precisely detect the track position on the written recording medium, thereby causing tracking servo error. Particularly, in high-density recording, the track pitch is decreased to increase the influence of write fringing.
The problem of write fringing significantly occurs when a leakage magnetic field reaches from the pole tip
108
to the pole tip layer P
2
(T). A possible method of suppressing the occurrence of write fringing is to decrease the width dimension of the pole tip
108
.
However, a decrease in the width dimension of the pole tip
108
causes a problem of magnetic saturation, thereby decreasing the magnetic flux density and deteriorating recording properties.
Therefore, the inductive head disclosed in U.S. Pat. No. 5,652,687 does not have a structure which can simultaneously prevent the occurrence of write fringing and magnetic saturation.
FIG. 24
is a partial front view showing a manufacturing step of a thin film magnetic head which is improved for suppressing the occurrence of write fringing.
In the step shown in
FIG. 24
, an insulating layer
5
is formed on a lower core layer
1
made of a magnetic material, and a trench
3
is formed in the insulating layer
5
to form the insulating layer
5
in the same shape as the notch structure
120
shown in FIG.
11
.
As shown in
FIG. 24
, a resist layer
4
is coated on the surface of the insulating layer
5
by spin coating to fill a portion of the trench
3
of the insulating layer
5
with the resist layer
4
.
Since the trench
3
formed in the insulating layer
5
is filled with the resist layer
4
, the thickness of the resist layer
4
formed on the insulating layer
5
decreases toward the trench
3
.
In the state shown in
FIG. 24
, the surface of the insulating layer
5
coated with the resist layer
4
is etched off, for example, by ion milling to cut the both edges
5
a
of the insulating layer
5
in the vicinity of the trench
3
. As a result, inclined surfaces
5
b
are formed at both edges
5
a
of the insulating layer
5
so that the distance between the inclined surfaces
5
b
decreases toward the lower core layer
1
, as shown in FIG.
25
.
After the resist layer
4
shown in
FIG. 25
is completely removed, the same layers as the pole tip layer P
1
(T), the gap layer G and the pole tip layer P
2
(T) shown in
FIG. 10
are laminated in the trench
3
shown in
FIG. 25
, and the same layer as the pole tip
108
shown in
FIG. 10
is further formed on the pole tip layer P
2
(T).
In this manufacturing method, the layer corresponding to the pole tip
108
shown in
FIG. 10
is formed along the inclined surfaces
5
b
of the insulating layer
5
. Since the layer corresponding to the pole tip
108
has a shape in which the width gradually increases away from the gap layer G, the leakage magnetic field shown by the broken lines in
FIG. 10
less occurs, thereby preventing the occurrence of write fringing on the both sides of the track width Tw.
However, in the process comprising forming the inclined surfaces
5
b
shown in
FIGS. 24 and 25
, the trench
3
is formed in the insulating layer
5
, and thus a variation easily occurs in the thickness of the resist layer
4
formed on the insulating layer
5
. Such a variation in the thickness of the resist layer readily causes variations in the inclination angle and the shape of the inclined surfaces
5
b
formed in the insulating layer
5
, thereby making quality unstable.
SUMMARY OF THE INVENTION
The present invention has been achieved for solving the above problems, and an object of the present invention is to provide a thin film magnetic head which is adaptable to track narrowing and which can effectively prevent write fringing and relieve magnetic flux saturation.
Another object of the present invention is to provide a thin film magnetic head for readily forming an inductive head with high reproducibility which can effectively suppress the occurrence of write fringing and magnetic flux saturation, and a method of manufacturing the thin film magnetic head.
A further object of the present invention is to provide a method of manufacturing a thin film magnetic head which is adaptable to track narrowing, and which can readily for
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
LandOfFree
Thin film magnetic head adaptable to track narrowing of... 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 adaptable to track narrowing of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head adaptable to track narrowing of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3145781