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Aqueous-Base Developable Negative Resist Systems

IP.com Disclosure Number: IPCOM000117188D
Original Publication Date: 1996-Jan-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Ito, H: AUTHOR [+2]

Abstract

Disclosed are syntheses of copolymers of HOST with styrene bearing pendant vic-diol or secondary alcohol and aqueous base developable negative resist systems based on acid-catalyzed dehydration of the alcohol copolymers.

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Aqueous-Base Developable Negative Resist Systems

      Disclosed are syntheses of copolymers of HOST with styrene
bearing pendant vic-diol or secondary alcohol and aqueous base
developable negative resist systems based on acid-catalyzed
dehydration of the alcohol copolymers.

      Acid-catalyzed dehydration of pendant alcohol including pinacol
rearrangement of vic-diol, has been successfully employed in the
design of chemically amplified negative resist systems that can be
developed with alcohol.  However, aqueous development is becoming the
industry's standard.  Pinacol rearrangement of small vic-diols to
ketones or aldehydes in phenolic resins has provided aqueous base
developable negative resist systems.  However, the copolymer approach
disclosed in this article is more attractive as it allows utilization
of a polyhydroxystyrene (PHOST) structure which is highly transparent
in the 248 nm region while PHOST is a poor matrix resin in the blend
approach because of its excessive dissolution rate in aqueous base.

      3-Methyl-2-(4-vinylphenyl)-2,3-butanediol was copolymerized
with p-acetoxystyrene (ACOST) using 2,2'-azobis(isobutyronitrile)
(AIBN) in tetrahydrofuran (THF) at 60ºC.  The ACOST copolymer
(Msub n=30, 200 and Msub w=51,500) was cleanly deacylated with
ammonium hydroxide in methanol without any complication to afford a
pinacol/HOST copolymer (17/83) with Msub n=25,900 and Msub w=42,400.
Use of p-t-butoxycarbonyloxystyrene (BOCST) as a comonomer resulted
in a slightly cross linked HOST copolymer although the thermal
deprote...