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Hardware Modifications for Eliminating Carbon Target Spitting

IP.com Disclosure Number: IPCOM000115637D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Darby, TP: AUTHOR [+6]

Abstract

Two main factors are responsible for carbon target spitting in the sputtering process. First, carbon redeposited onto the target results in an insulating film on a portion of the target surface. Electrical breakdown or arcing to the surrounding areas can cause spitting. The second factor is flaking of carbon films from hardware adjacent to the carbon targets. These flakes can cause momentary electrical shorts between components of the deposition sources or between the plasma and the target. Both these conditions can cause spitting.

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Hardware Modifications for Eliminating Carbon Target Spitting

      Two main factors are responsible for carbon target spitting in
the sputtering process.  First, carbon redeposited onto the target
results in an insulating film on a portion of the target surface.
Electrical breakdown or arcing to the surrounding areas can cause
spitting.  The second factor is flaking of carbon films from hardware
adjacent to the carbon targets.  These flakes can cause momentary
electrical shorts between components of the deposition sources or
between the plasma and the target.  Both these conditions can cause
spitting.

      To minimize carbon target spitting, the polecap, outer shield,
and anode cap of the sputtering sources have been redesigned.  The
gap in the polecap is widened to spread the magnetic field in front
of the target surface.  The result is that the full target surface is
sputter-etched, thereby eliminating the redeposition carbon film.

      The outer shield was redesigned to increase the surface area
exposed to the flux of carbon atoms that are sputtered directly to
the shield.  This results in a decrease in the rate at which the
carbon film builds up on the shield as well as a change in the
structure and stress of the deposited carbon film.  Both these
conditions can lead to a significant increase in the critical
thickness at which flaking starts.  To further reduce the area that
will flake, the outer shield and anode cap are fabricated with as
shar...