Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
2000-02-18
2001-01-30
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
C216S066000
Reexamination Certificate
active
06180421
ABSTRACT:
The present invention relates to a method of manufacturing a magnetic head for recording or reproducing information to or from a magnetic recording medium of magnetic disk apparatus or magnetic tape apparatus, and more particularly, to a head having a narrow core width for higher magnetic field intensity.
BACKGROUND OF THE INVENTION
With the realization of high recording density of a magnetic recording medium, high performance of magnetic heads is now required. In order to realize high recording density, the line recording density and track density of a magnetic recording medium must be improved, which means a magnetic head should assure high frequency recording and less recording blur. Here, a “recording blur” means the phenomenon of the recording magnetic field spreading in the track width direction at the time of data writing enough to influence adjacent tracks.
Particular attention is now focused on magneto-resistive (“MR”) heads that can be used for a small size disk apparatus while assuring high output which does not depend on the velocity of the magnetic recording medium. This MR head satisfies the requirement for high recording density. As a magnetic head having a MR head, a specific magnetic head called a composite type head is well known. This composite type head is formed by stacking in the laminating direction. It has a reproducing head of multilayer structure to read magnetic information from a magnetic recording medium and a recording head of multilayer structure to write information to the magnetic recording medium.
There is a member at the boundary of the reproducing head and the recording head. In particular, a magnetic shield layer (upper magnetic shield layer) in the side of the reproducing head is also used as the lower magnetic pole in the side of the recording head among a pair of magnetic poles of the recording head. Therefore, the surface (ABS or floating surface) of the lower magnetic pole, which is part of the recording head opposite to the magnetic recording medium, is formed wider than the width of the recording tracks of the magnetic recording medium. As a result, in the writing operation, the recording magnetic field is generated from the lower magnetic pole, which spreads widely in the track direction of the recording medium. However, it becomes difficult to narrow the track width and reduce the track pitch, both being requirements for high recording density. Both upper and lower magnetic poles of the recording head are connected at the center area of an eddy type recording coil, and a recording magnetic field is generated over the Air Bearing Surface (“ABS”) between the lower magnetic pole and the upper magnetic pole. In order to improve the recording density, it is required to set the core width of the ABS of the upper magnetic pole to a small size (1 &mgr;m or less) to reduce the recording blur. However, there are some barriers for realizing fine width of the core.
As illustrated in
FIG. 1
, since a recording coil
112
is embedded in an interlayer insulating layer
111
formed between the upper and lower magnetic poles, a large difference of levels exists at the surface of the interlayer insulating layer
111
. Therefore, liquid resist
115
, coated on the interlayer insulating layer
111
, used in the process of forming the upper magnetic pole, flows toward the lower level area. As a result, the resist
115
becomes thin at the higher level area (flat area) but becomes comparatively thick at the lower level area (bottom area).
In the process of forming the upper magnetic pole, resist
115
is first formed at the surface of interlayer insulating layer
111
and is then patterned to the predetermined shape. The upper magnetic pole is formed by plating on the area of the interlayer insulating layer
111
from which the resist
115
is removed. In order to form the upper magnetic pole in the predetermined thickness, the thickness of the resist on the flat area is required to be about 6 &mgr;m. However, due to the existence of level (or thickness) differences of the interlayer insulating layer, the thickness of the resist on the bottom area becomes about 10 &mgr;m. Here, it is very difficult to realize a target core width of 10 &mgr;m or less for the ABS of the upper magnetic pole when the resist is formed in the thickness of 10 &mgr;m or more.
In order to solve this problem, the applicant of the present invention has proposed, in Japanese Published Unexamined Patent Application No. HEI 9-109845 (Apr. 25, 1997), a partial trimming technique for the upper magnetic pole using a focused ion beam (FIB). In particular, it has been proposed that the upper magnetic pole be locally trimmed by the FIB method from the ABS surface side in order to narrow the core width during composite type magnetic head manufacturing process.
FIGS.
2
(
a
) and
2
(
b
) show a process of trimming the upper magnetic pole using the focused ion beam method. As shown in FIG.
2
(
a
), the upper magnetic pole
116
covers a part of an eddy type recording coil
112
. Moreover, the upper magnetic pole
116
includes a pole
116
a
which is elongated in the area adjacent to the recording medium.
FIG.
2
(
b
) is a view showing the trimming process using the focused ion beam method for the pole
116
a
. In the trimming process, the lower magnetic pole located at both side portions and the lower area of the pole
116
a
(the area in contact with the gap layer of the upper magnetic pole
116
) is trimmed by irradiation of the focused ion beam. With this trimming process, the width of the pole
116
a
of the upper magnetic pole
116
is shaped to the desired size, and a groove (trench) or recess is formed in the upper layer of the lower magnetic pole located at both lower areas of the pole.
As explained above, the width of the pole
116
a
can be finished in the fine dimension using the focused ion beam method. Spread in the track width direction of the recording magnetic field generated between the upper and lower magnetic poles can be minimized using the upper magnetic pole
116
having the pole of fine width. As a result, the writing of data in higher track density can be realized on the magnetic recording medium.
However, trimming of the upper magnetic pole using the focused ion beam will deteriorate productivity. In the focused ion beam method, the ion beam is focused to predetermined positions in both sides of the pole to set the ion irradiation area in every head element to trim the width of the pole to 1 &mgr;m or less. Because a plurality of head elements are formed on a wafer substrate, longer time is required since the process must be repeated for each head element. For example, even if the processing time of one head element is about 10 seconds, it will take over a day (27.7 hours) for processing only a sheet of wafer because there are about 10,000 heads in a 5-inch wafer, which is still comparatively small in size. It is simply not practical to use focused ion beam equipment for actual production.
The applicant of the present invention has proposed to replace the use of the focused ion beam method disclosed in Japanese Published Unexamined Patent Application No. HEI 10-184780 (Jun. 25, 1998) for trimming the upper magnetic pole with the ion milling method.
FIGS.
3
(
a
) and
3
(
b
) illustrate the trimming of the upper magnetic pole using the ion milling method. FIG.
3
(
a
) is a plan view of the upper magnetic pole, and FIG.
3
(
b
) is a cross-sectional view along the line B—B of FIG.
3
(
a
).
First, as illustrated in FIG.
3
(
a
), resist
26
is coated to the area, except for the object area of trimming when the upper magnetic pole
116
is formed. In practice, the pole
116
a
of the upper magnetic pole and the area, except for the lower magnetic pole
114
located at the lower area of the pole, are covered with resist. The trimming is performed by radiating the side surface of an elongated pole of the upper magnetic pole and the upper layer of the lower magnetic pole with the ion beam as shown in FIG.
3
(
b
) as the substrate is rotated. In the initial stage o
Futai Hideaki
Hosono Kazumasa
Ohtsuka Yoshinori
Okada Mitsumasa
Bowers Charles
Fujitsu Limited
Greer Burns & Crain Ltd.
Kielin Erik
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