Thin-film magnetic write head

Details Thin-film magnetic write head Thin-film magnetic write head

2000-08-30

2003-05-06

Klimowicz, William (Department: 2652)

Dynamic magnetic information storage or retrieval

Head

Magnetoresistive reproducing head

C360S125330

Reexamination Certificate

active

06560076

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic write head, such as a floating type magnetic head, and to a method of fabricating the same. More particularly, the invention relates to a thin-film magnetic write head suitable for track narrowing that writes data onto a recording medium as reliably-readable signals for a magnetic read head and to a method of fabricating the same.
2. Description of the Related Art
A thin-film magnetic head has an inductive head and a magnetoresistive (MR) head. The thin film magnetic head may be mounted in a hard disk drive and the like. The inductive head is for writing signals onto a recording medium, such as a hard disk. The MR head for reading signals from the recording medium.
In general, an inductive head includes a lower core layer composed of a magnetic material, an upper core layer which is opposed to the lower core layer with a nonmagnetic gap layer therebetween at a surface facing a recording medium, and a coil layer for inducing a recording magnetic field in the core layers. Magnetic signals are written onto the recording medium by means of a fringing magnetic field between both core layers.
With increasing recording density, there is a need to cope with the narrowing of the track by decreasing the track width T
w
of the inductive head. The track width T
w
is determined by the width of the edge of the upper core layer that is exposed at a surface facing the recording medium—the air-bearing surface (hereinafter “ABS”).
For example, conventionally, the upper core layer is formed by a frame plating method. In the frame plating method, a resist layer patterned in the shape of the upper core layer is formed. The interior of the pattern is then plated with a magnetic material for forming the upper core layer. By removing the resist layer, an upper core layer with an edge having a width corresponding to the track width T
w
is obtained.
However, in the frame plating method, it is very difficult to pattern the resist layer with a minute track width T
w
because the resolution of exposure has limitations when the resist layer is patterned. As the recording density further increases, this problem becomes more noticeable.
Japanese Unexamined Patent Application Publication No. 7-296328 (hereinafter “UNEXAMINED APPLICATION”) discloses a structure of an inductive head formed by another frame plating method and a method of fabricating the same.
FIG. 10
is an enlarged partial front view of the periphery of a core of the inductive head which is formed by the frame plating method disclosed in the UNEXAMINED APPLICATION.
As shown in
FIG. 10
, a notch structure
120
composed of silicon dioxide or the like is formed on a lower pole layer (lower core layer)
102
.
FIG. 11
is a perspective view, which shows the shape of the notch structure
120
. The notch structure
120
is provided with a trench
148
. A pole tip layer P
1
(T), a gap layer G, and a pole tip layer P
2
(T) are formed by plating in the trench
148
.
A pole tip
108
of an upper pole layer (upper core layer) having a larger width than that of the pole tip layer P
2
(T) is formed on the pole tip layer P
2
(T) and the notch structure
120
.
The UNEXAMINED APPLICATION describes a thin-film magnetic write head having a submicron track width can be provided. The UNEXAMINED APPLICATION further describes the prevention of magnetic saturation associated with narrowing of a track by the formation of the pole tip
108
having a larger width than that of the pole tip layer P
2
(T), as shown in FIG.
10
.
In the method described in the UNEXAMINED APPLICATION, the pole tip layer P
1
(T), the gap layer G, and the pole tip layer P
2
(T) are formed in the trench
148
by electroplating using a direct current. However, if the inner width of the trench
148
is set at 1 &mgr;m or less in order to provide a thin-film magnetic write head having a submicron track width. the surface of the pole tip layer P
1
(T) is curved as shown in FIG.
12
. Consequently, the surface of the gap layer G deposited on the pole tip layer P
1
(T) is also curved.
As shown in
FIG. 13
, if the surface of the gap layer G is curved with respect to a recording track on a recording medium in which data are recorded by the thin-film magnetic write head, a boundary B for reversal of magnetization on the recording track is curved in the direction of motion of the magnetic track (X direction).
If the boundary B is curved, it is difficult to read the data with high definition. When a read head H is in the vicinity of the boundary B as shown in
FIG. 13
, both ends of the read head H and the central section of the read head H are located in reversed magnetization regions R
+
and R
−
, respectively. The magnetization regions have different magnetization directions. As a result, the read outputs cancel each other out.
The surface of the pole tip layer P
1
(T) is curved because it is difficult to obtain uniform current distribution in the trench
148
during plating when the inner width of the trench
148
is 1 &mgr;m or less. Conventionally, when plating is performed in the trench
148
, electroplating is performed using a direct current.
When electroplating is performed using a direct current, if the current density is decreased to less than 30 mA/cm
2
, the current distribution in the trench
148
becomes nonuniform. In particular, the pole tip layer P
1
(T) is curved, and consequently, the gap layer G is also curved.
Even increasing the current density during electroplating so the current distribution in the trench becomes uniform is of no avail. If the current density is increased to more than 30 mA/cm
2
when electroplating is performed using a direct current, “burnt deposits” occur. The plating surface becomes turbid and rough, instead of being bright and uniform. Thus the quality of the gap layer G is degraded.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a thin-film magnetic write head in which the curvature of the surface of a gap layer is reduced even if a track width is 1 &mgr;m or less, and in which data can be written onto a recording medium as signals reliably readable by a magnetic read head. A further object is to provide a method of fabricating the thin film magnetic write head.
In one aspect of the present invention, a thin-film magnetic write head includes a lower core layer and an upper core layer with a nonmagnetic gap layer therebetween at a surface facing the recording medium (ABS). The lower core layer is composed of a magnetic material. The upper core layer is composed of a magnetic material that is opposed to the lower core layer. The thin-film magnetic write head writes data to be read by a thin-film magnetic read head having a track width T
r
and a distance H
2
between an upper shielding layer and a lower shielding layer. A length in the track width direction (track width) at a magnetic contact between the gap layer and the upper core layer is 1 &mgr;m or less. The formula A≦H
1
−H
2
is satisfied. A is a difference between the height of the upper surface of the gap layer on a center line in the track width direction and the height of the upper surface of the gap layer at a distance T
r
/2 from the center line in the track width direction. H
1
is a gap length of the gap layer. H
2
is the distance between the upper and lower shielding layers.
It is preferable that the surface of the gap layer of the thin-film magnetic write head is completely planar. However, in practice, a curvature is allowed to a certain extent depending on the size of the thin-film magnetic read head. The formula A≦H
1
−H
2
defines a tolerance for the curvature of the gap layer.
FIG. 1
is a schematic diagram illustrating the formula A≦H
1
−H
2
.
The thin-film magnetic write head writes data into the recording medium while reversing magnetization directions. The recording track for recording data is shaped like a band in which reversed magnetization regions R
+
and reversed magnetization

Affiliated with

Also associated with

Rating

Thin-film magnetic write 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 write head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin-film magnetic write head will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3002228