Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
2000-06-16
2004-04-20
Olsen, Allan (Department: 1763)
Etching a substrate: processes
Forming or treating article containing magnetically...
C216S037000, C216S066000, C216S075000
Reexamination Certificate
active
06723252
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods for fabricating magnetic heads, and more particularly to methods for notching the P
1
magnetic pole of such magnetic heads.
2. Description of the Prior Art
One approach to increasing the areal data storage density of magnetic disks is to narrow the width of the data tracks written on the disks, such that more tracks per inch can be written, and therefore more data stored on the disk in a given area. Generally, the width of the base of the P
2
magnetic pole tip determines the width of the data track; however, it is also necessary to provide some spacing between adjacent tracks, and the spacing required between data tracks is a function of the strength of the fringing magnetic fields that are created by the magnetic head. In some prior art magnetic heads, the fringing fields can be strong enough to affect data in neighboring data tracks, and the width of a fringing magnetic field can be a significant portion of a data track itself. Therefore, it is desirable to minimize the fringing fields generated by magnetic heads, such that adjacent data tracks can be written more closely together, and the areal data storage density on the disk thereby increased.
One of the fabrication methods that has been undertaken in the prior art to reduce the fringing fields is to notch the P
1
magnetic pole, as is known to those skilled in the art. Such P
1
pole notching can substantially reduce the fringing magnetic fields generated by the magnetic head, and can thereby increase the areal data storage density on the disk. The standard P
1
notching process of the prior art utilizes the previously fabricated P
2
pole tip as an etching mask element in the notching process, and the process includes first etching through the write gap layer, typically alumina (Al
2
O
3
), and then etching into the P
1
pole layer (typically permalloy, a NiFe compound). A problem that initially exists in the prior art P
1
notching process is that an argon ion beam was utilized to etch the P
1
pole notches, and the alumina write gap layer is significantly more resistant to etching by the argon ion beam than the NiFe material of the P
2
pole tip and the P
1
layer. Therefore, where an argon ion beam was used in the prior art to conduct the P
1
notching step, significant portions of the P
2
pole tip were etched away while the beam more slowly etched through, the alumina write gap layer. Thereafter, further portions of the P
2
pole tip were etched away while the P
1
pole was subsequently notched by the ion beam. As a result, the earlier prior art P
1
pole notching process required the initial fabrication of a rather thick P
2
pole tip, such that a properly sized P
2
pole tip remained following the etching in the P
1
notching step utilizing an argon ion beam.
A prior art improvement in P
1
notching involves the initial utilization of a first etchant gas species accelerates the etching of the alumina write gap layer and slows down the etching of the NiFe P
2
pole tip material. Such a prior art etchant gas is CHF
3
, and following the use of CHF
3
in the etching process to etch through the alumina write gap layer, the etchant gas was changed to argon to notch the P
1
pole. As a result, a much smaller portion of the P
2
pole tip was etched away during the P
1
notching step than was previously the case. This prior art also teaches that a decrease of the NiFe etch rate in CHF
3
milling occurs due to the formation of a polymer layer on the surface of the NiFe pole.
A problem that has arisen with the use of CHF
3
in the etching process is that it creates excessive polymer deposition. The polymer deposition can cause product contamination and results in the need for frequent cleaning and maintenance of the tooling hardware. Such polymers are apparently created in chemical reactions associated with the ionization of the CHF
3
etchant gas, creating a significant problem in the utilization of CHF
3
for P
1
notching. The present invention avoids the excessive polymer deposition problems of CHF
3
while maintaining the benefits of the two-step P
1
pole notching process. Specifically, the present invention is a P
1
notching process utilizing C
2
F
6
as a preferred substitute for CHF
3
.
SUMMARY OF THE INVENTION
The present invention includes a two-step etching process for notching the P
1
pole of the write head element of a magnetic head. In a first step, the preferred embodiment utilizes a combination of C
2
F
6
and argon gases (designated as C
2
F
6
/Ar) as the etchant gas to preferentially etch portions of the alumina write gap layer. Thereafter, in the second step, argon is used as the etchant gas to preferentially etch the P
1
pole material. The C
2
F
6
/Ar etchant gas preferably includes C
2
F
6
gas in a concentration range of from 50% to 90%, with a preferred concentration range being from 70% to 80%. The etching of the alumna write gap layer is preferably conducted with a first echant ion beam angle of from 5° to 30°, and a second etchant ion beam angle of from 65° to 85°.
It is an advantage of the P
1
notching process of the present invention that contamination of magnetic head during a P
1
notching step is reduced.
It is another advantage of the P
1
notching process of the present invention that it avoids frequent cleaning and maintenance of the tooling hardware.
It is a further advantage of the present invention that a two-step P
1
notching process has been developed that rapidly etches the write gap layer in a first step and rapidly etches the P
1
layer in a second step.
It is yet another advantage of the present invention that a magnetic head is reliably manufactured that has reduced fringing magnetic fields.
It is yet a further advantage of the present invention that a magnetic head has been developed having a right head element that produces reduced fringing magnetic fields, such that the areal data storage density on hard disks can be increased.
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patent: 4592801 (1986-06-01), Hara et al.
patent: 5316617 (1994-05-01), Kawabe et al.
patent: 5441596 (1995-08-01), Nulty
patent: 5445712 (1995-08-01), Yanagida
patent: 5811357 (1998-09-01), Armacost et al.
patent: 5932492 (1999-08-01), Hahm et al.
patent: 6180421 (2001-01-01), Futai et al.
patent: 6226149 (2001-05-01), Dill et al.
patent: 6238582 (2001-05-01), Williams et al.
patent: 6282776 (2001-09-01), Otsuka et al.
patent: 11053727 (1999-02-01), None
Hsiao Richard
Kim John I.
Guillot Robert O.
IPLO -Intellectual Property Law Offices
Olsen Allan
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