Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-05-01
2004-05-04
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06731459
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head provided with an induction type magnetic recording head and a method of manufacturing the same.
2. Description of the Related Art
A composite type thin film magnetic head including a magnetoresistive (MR) head used for data reproduction and an induction type magnetic head used for data recording is used as a magnetic head of a magnetic disk device.
The MR head includes any one of an AMR (Anisotropic Magnetoresistive) component using an AMR effect, a GMR (Giant Magnetoresistive) component using a GMR effect, and a TMR (Tunneling Magnetoresistive) component using a tunnel junction film indicating a magnetoresistive effect. As the surface recording density of a magnetic recording medium becomes high, a component to be used is changed from the AMR component to the GMR component, and further, to the TMR component.
As one factor for determining the performance of the MR head, there is optimization of an MR height. The MR height is a height of the MR component from an end portion at a side facing an air bearing surface (ABS) opposite to a magnetic recording surface of a magnetic recording medium to an end portion at the opposite side, and this height depends on an amount of polishing of the ABS surface in a head manufacturing process.
The induction type magnetic head realizes a ring structure having a narrow gap by a semiconductor process, and includes upper and lower magnetic pole layers which are laminated through an insulating film and has a gap (write gap) at the side facing the ABS surface to form a closed magnetic path, and a thin film coil formed in the insulating film between upper and lower magnetic poles. The head material is magnetized to have high magnetic flux density by a recording current flowing through the thin film coil, and a predetermined leakage magnetic field is formed over the gap to record data.
As one factor for determining the performance of the induction type magnetic head, there is optimization of a throat height (TH). The throat height is a height of the magnetic pole from the ABS surface to the end portion of the insulating film, and this height also depends on an amount of polishing of the ABS surface in the head manufacturing process. In order to improve the head efficiency of the recording head, it is necessary to make the throat height as short as possible.
In order to raise the recording density, it is necessary to raise the track density of the magnetic recording medium. For that purpose, it is necessary to realize a recording head in which a magnetic pole width and a gap width at the ABS surface are made narrow; therefore a semiconductor processing technique is used.
The foregoing composite type thin film magnetic head is manufactured through a plurality of manufacturing processes, for example, a sputtering process, a photolithography process, a frame plating process, an etching process, a polishing process, and the like. Hereinafter, an example of a method of manufacturing a thin film magnetic head will be described in brief by use of the thin film magnetic head having a so-called step gap structure.
First, an Al
2
O
3
TiC substrate having high hardness and excellent in wear resistance is used. When the magnetic head is completed, this substrate itself functions as a slider body of the magnetic head. The reason why the substrate having high hardness and excellent in wear resistance is used is to secure the floating accuracy of the head and to obtain an accurate MR height and throat height.
Then, for example, a chromium film excellent in adhesiveness is formed on the Al
2
O
3
TiC substrate by sputtering or the like. Next, a lower shield layer made of, for example, permalloy is formed. Next, an MR component interposed between insulating films is formed on the lower shield layer.
Next, an upper shield layer made of, for example, permalloy is formed. By this, an MR head for reproduction is completed. The upper shield layer is also used as a lower magnetic pole layer of an induction type magnetic head for recording. Next, a thin film coil made of copper or the like is formed on the lower magnetic pole layer through an insulating film by a frame plating method or the like.
Next, after the thin film coil is embedded in an insulating film and flattening is made, a recording gap layer is formed on an upper layer. A process from the formation of the recording gap layer to the formation of an upper magnetic pole layer will be described in brief with reference to
FIGS. 9A
to
9
F and
FIGS. 10A
to
10
F. In
FIGS. 9A
to
9
F and
FIGS. 10A
to
10
F,
FIGS. 9A
,
9
C and
9
E and
FIGS. 10A
,
10
C and
10
E show sections vertical to the ABS surface, and show the sections taken along line A—A shown in FIG.
9
B.
FIGS. 9B
,
9
D and
9
F and
FIGS. 10B
,
10
D and
10
F show partial planes near the ABS surface.
First, as shown in
FIGS. 9A and 9B
, a stepped portion (step gap)
158
of a nonmagnetic material with an almost vertical end face
159
at a side facing the ABS surface (see
FIG. 10F
) is formed on a recording gap layer
112
.
Next, as shown in
FIGS. 9C and 9D
, after a seed layer
151
for a plating treatment is formed, as shown in
FIGS. 9E and 9F
, a positive resist
152
is coated on the entire surface and patterning is made to form a resist frame
153
(see FIGS.
10
A and
10
B).
Next, as shown in
FIGS. 10C and 10D
, a plating film made of, for example, permalloy is formed by a frame plating method using the formed resist frame
153
as a mold, and then, the resist frame
153
is removed and an upper magnetic pole layer
113
is formed (see FIGS.
10
E and
10
F).
Although not shown below, etching is carried out using the upper magnetic pole layer
113
at the side facing the ABS surface as a mask, so that the recording gap layer is patterned. The upper magnetic pole layer is formed so as to be magnetically connected to the lower magnetic pole layer through the coil at the opposite side of the recording gap layer so that a closed magnetic path is formed. A protection film is formed on the upper layer of the upper magnetic pole layer, and the film forming process is ended.
Next, the Al
2
O
3
TiC substrate is cut into rod-like substrates including several tens of heads. The ABS formation surface of the rod-like substrate is polished to provide the throat height of a height of several &mgr;m. After the ABS surface is formed, the rod-like substrate is cut, so that a plurality of thin film magnetic heads are completed.
Like this, in the thin film magnetic head of the step gap structure, for example, as shown in
FIGS. 10E and 10F
, the stepped portion
158
of the nonmagnetic material in which the end face
159
at the side facing the ABS surface is formed almost vertically, is formed on the recording gap layer
112
. By making the step gap structure, the upper magnetic pole layer
113
can be formed on the flattest possible surface.
Besides, according to the step gap structure, the throat height is defined as a height from the ABS surface to the end face
159
of the stepped portion
158
. Here, the position of the end face
159
of the stepped portion
158
becomes a throat height zero (TH
0
) position. Thus, an interval between the not-shown lower magnetic pole layer and the upper magnetic pole layer
113
is a constant interval equal to the thickness of the recording gap layer
112
from the ABS surface to the throat height zero position, and abruptly becomes large from the throat height zero position (that is, the position of the end face
159
) at the opposite side to the ABS surface.
However, like this, in the structure where the interval between the lower magnetic pole layer and the upper magnetic pole layer is abruptly changed in the vicinity of the throat height zero position, the flow of a magnetic flux passing through the magnetic pole layer and directed toward the recording gap layer is abruptly changed in the vicinity of the throat height zero position. Thus, there occurs a problem that the magnetic flux is saturate
Miller Brian E.
Oliff & Berridg,e PLC
TDK Corporation
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