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Top Surface Imaging using a Photoactive Inorganic System

IP.com Disclosure Number: IPCOM000110798D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Baum, TH: AUTHOR [+3]

Abstract

A photoactive inorganic system of potassium iron (III) oxalate and palladium (II) chloride was used to achieve top- surface images which could subsequently be used as a mask for reactive ion etching (RIE) of polymeric materials. Masked UV irradiation of the iron-palladium system results in the selective formation of palladium metal "seeds" which are useful for activating electroless metal plating from solution. This approach enables the selective formation of metal patterns which are resistant to plasma etching and serve as a top-surface mask for pattern transfer to the underlying polymeric layer. Using this method, etched pattern transfer into a wide variety of polymeric materials, which are not specifically designed for lithographic or patterning processes, can be achieved.

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Top Surface Imaging using a Photoactive Inorganic System

      A  photoactive  inorganic  system  of  potassium  iron (III)
oxalate and palladium (II) chloride was used to achieve top- surface
images which could subsequently be used  as  a  mask for  reactive
ion  etching  (RIE)  of  polymeric materials.  Masked UV irradiation
of the iron-palladium  system  results in  the selective formation of
palladium metal "seeds" which are useful for activating  electroless
metal  plating  from solution.  This  approach enables the selective
formation of metal patterns which are resistant  to  plasma  etching
and serve  as  a  top-surface  mask  for pattern transfer to the
underlying polymeric layer.  Using this method,  etched  pattern
transfer into a wide variety of polymeric materials, which are not
specifically designed for lithographic or patterning processes, can
be achieved.

      The use of top-surface imaging for pattern  transfer  is
illustrated  in  the  following example.  A silicon substrate was
coated with a 3  &mu.m  thick  layer  of  polyimide  (RC 5878).   The
sample  was  then  spin-coated  with  a  thin photoactive  layer  of
potassium  iron  (III)  oxalate  and palladium  (II)  chloride.
Masked UV irradiation with a conventional exposure tool (15 to 60
seconds) results in photoreduction of the palladium (II) species.
Immersion of the sample into an electroless copper-plating solution
(150 seconds)  results  in a thin, continuous metal film which is
selectively formed only in the UV  exposed  regions  of  the sample.
The sample is then etched in an oxygen-based plasma (180 seconds) to
transfer the image into the polyimide layer...