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SELECTIVE MILLING BY VARIABLE SPEED/ANGLE STAGE ROTATION

IP.com Disclosure Number: IPCOM000014603D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 1 page(s) / 26K

Publishing Venue

IBM

Related People

C HWANG: AUTHOR [+3]

Abstract

In standard applications of material removal by ion milling, the substrate is rotating at a constant rotational speed during the milling to help achieve best uniformity of material removal across the substrate. When the process is used during the later stages of a wafer build, for example in the case of the ion milling operation during the write element build for a magnetic recording head structure, surface topography will cause localized variations in the milling removal rate due to shadowing effects. For the case where there is normal incidence for the ion beam, divergence within the beam results in some shadowing of the off-normal components of the ion beam. The shadowing effect is even larger when the ion beam is intentionally set at an off-normal angle of incidence. One example commonly observed in fabrication of magnetic recording head wafers is the NiFe plating seedlayer extension, or “foot”, which can be left at the thick write head pole track edge. Any ion milling process capable of reducing this shadowing effect in critical regions of the magnetic head would be desirable.

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SELECTIVE MILLING BY VARIABLE SPEED/ANGLE STAGE ROTATION

In standard applications of material removal by ion milling, the substrate is
rotating at a constant rotational speed during the milling to help achieve
best uniformity of material removal across the substrate. When the process is
used during the later stages of a wafer build, for example in the case of the
ion milling operation during the write element build for a magnetic recording
head structure, surface topography will cause localized variations in the
milling removal rate due to shadowing effects. For the case where there is
normal incidence for the ion beam, divergence within the beam results in some
shadowing of the off-normal components of the ion beam. The shadowing effect
is even larger when the ion beam is intentionally set at an off-normal angle
of incidence. One example commonly observed in fabrication of magnetic
recording head wafers is the NiFe plating seedlayer extension, or "foot",
which can be left at the thick write head pole track edge. Any ion milling
process capable of reducing this shadowing effect in critical regions of the
magnetic head would be desirable.

   An improvement to the ion milling removal
process, where topography is present, is the use of
variable rotational speed of the substrate within a
complete 360 degree revolution while keeping all
other ion milling parameters constant. The angular
speed of the substrate as a function of its angular
position would be predetermined by the location of
cri...