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Enhanced Metal Polish: Corrosion Control by Temperature Friction Generated Heat Reduction

IP.com Disclosure Number: IPCOM000121426D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Brooks, GA: AUTHOR [+4]

Abstract

The AlCu polishing operation employed a chemical/mechanical technique whereby oxidation followed by mechanical abrasion takes place in rapid succession. During this period of removing the metal, heat builds up due to friction at the polishing pad/wafer interface. In order to dissipate the heat one must rely on rapid heat transfer through the wafer into the quill and via polishing pad. Due to the poor conductivity of the pad material, heat must be dissipated via the substrate (wafer). Corrosion will occur fastest at porous sites, as in seams, and spreads to denser metal. We have found that the removal rate of AlCu at 140 rpm and 80 rmp (tool #6) was approximately 1:1. However, under the same process conditions, the maximum temperature at 140 rpm was 6-7 degrees C higher than the maximum temperature 80 rpm.

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Enhanced Metal Polish: Corrosion Control by Temperature Friction
Generated Heat Reduction

      The AlCu polishing operation employed a chemical/mechanical
technique whereby oxidation followed by mechanical abrasion takes
place in rapid succession.  During this period of removing the metal,
heat builds up due to friction at the polishing pad/wafer interface.
In order to dissipate the heat one must rely on rapid heat transfer
through the wafer into the quill and via polishing pad.  Due to the
poor conductivity of the pad material, heat must be dissipated via
the substrate (wafer). Corrosion will occur fastest at porous sites,
as in seams, and spreads to denser metal.  We have found that the
removal rate of AlCu at 140 rpm and 80 rmp (tool #6) was
approximately 1:1.  However, under the same process conditions, the
maximum temperature at 140 rpm was 6-7 degrees C higher than the
maximum temperature 80 rpm.  This 6-7 degrees C differential achieved
as a function of rpm is significant in retarding corrosion as
demonstrated in earlier work.  A 10 degrees C rise in temperature
would increase the corrosion rate by a factor of two.  Therefore, the
decrease in rpm does not affect the AlCu polish removal rate, but
does in fact reduce the rate and amount of corrosion that may occur.

      Anonymous.