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Dual-Tone Resist Composition

IP.com Disclosure Number: IPCOM000105554D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Ito, H: AUTHOR [+2]

Abstract

The tBOC resist can be imaged in either positive or negative mode depending on the polarity of developer solvent. The polarity change from a nonpolar to a polar state as embodied in the tBOC resist is accomplished by acid-catalyzed deprotection, which has attracted a great deal of attention and is currently pursued by many research groups for the design of aqueous base developable, positive resist systems for replacement of novolac/diazoquinone resists. The polarity change mechanism involving acid-catalyzed deprotection has been found extremely useful in high contrast selective silylation for oxygen RIE dry development processes.

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Dual-Tone Resist Composition

      The tBOC resist can be imaged in either positive or negative
mode depending on the polarity of developer solvent.  The polarity
change from a nonpolar to a polar state as embodied in the tBOC
resist is accomplished by acid-catalyzed deprotection, which has
attracted a great deal of attention and is currently pursued by many
research groups for the design of aqueous base developable, positive
resist systems for replacement of novolac/diazoquinone resists.
The polarity change mechanism involving acid-catalyzed deprotection
has been found extremely useful in high contrast selective
silylation for oxygen RIE dry development processes.

      Polarity alteration, through clean structural transformation,
could offer high resist contrasts, swelling-free developments,
and some versatile applications such as silylation.  We have
reported that pinacol rearrangement of pendant vic-diol to ketone
cleanly and facilely occurs in polymeric films.  Also reported is a
negative resist system based on acid-catalyzed intramolecular
dehydration of pendant tertiary alcohol to olefin for reverse
polarity change.  However, positive imaging with the
polymeric pinacol or poly[4-(2-hydroxy-2-propyl)styrene] was not
possible.  The lack of a positive tone in these systems is a result
of minor concomitant crosslinking.

Described is the first dual tone imaging system based on the reverse
polarity change.  The design utilizes acid-catalyzed dehydration of
pendant tertiary alcohol to olefin.  Polystyrene bearing a
pendant methyl phenyl carbinol structure can be cleanly converted by
reaction with photochemically generated acid to a polymer
with a 1,1-diphenylethylene moiety, which does not undergo any
further reactions, allowing negative imaging with alcohol and
positive imaging with xylene.

    4-(1-Phenyl-1-hydroxyethyl)styrene was synthesized by reacting
a methyl Grignard reagent with 4-benzoylstyrene, which had been in
turn prepared by Stille's Pd-catalyzed tin coupling reaction on
4-bromobenzophenone.  Polymerization of the methyl diphenyl carbinol
monomer was carried out with...