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Use of Peroxides Initiators in Preparation of Chemical Amplification Resins

IP.com Disclosure Number: IPCOM000108893D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 62K

Publishing Venue

IBM

Related People

Ito, H: AUTHOR

Abstract

Chemical amplification resist systems are becoming increasingly important in the ULSI fabrication. These resist systems provide extremely high sensitivities owing to the catalytic nature of the reactions incorporated in the design, which tends to make such systems vulnerable to impurities. One such impurity could be polymer end groups. In contrast to radiation-induced molecular weight changes such as main chain scission and crosslinking, the side chain deprotection chemistry incorporated in the tBOC resist should not be affected by molecular weight in principle. However, the resist sensitivity decreases as molecular weight is reduced due to increasing concentration of end groups. Low molecular weight materials tend to give better positive imaging performance in many cases.

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Use of Peroxides Initiators in Preparation of Chemical Amplification Resins

      Chemical amplification resist systems are becoming increasingly
important in the ULSI fabrication.  These resist systems provide
extremely high sensitivities owing to the catalytic nature of the
reactions incorporated in the design, which tends to make such
systems vulnerable to impurities.  One such impurity could be polymer
end groups. In contrast to radiation-induced molecular weight changes
such as main chain scission and crosslinking, the side chain
deprotection chemistry incorporated in the tBOC resist should not be
affected by molecular weight in principle. However, the resist
sensitivity decreases as molecular weight is reduced due to
increasing concentration of end groups.  Low molecular weight
materials tend to give better positive imaging performance in many
cases.  Then, it becomes important to carefully design polymer end
groups by selecting proper initiators for polymerization.

      Although poly(p-t-butoxycarbonyloxystyrene) (PBOCST) can be
prepared by cationic polymerization in liquid sulfur dioxide, radical
polymerization is much easier to run especially in a large-scale
preparation. a,a-Azobis(isobutyronitrile) (AIBN) is the most commonly
used radical initiator, which attaches its cyano group to the
initiator side of the polymer chain.  Thus, when AIBN is used as the
initiator, a high molecular weight PBOCST (Mn=63,000) provides a
higher sensitivity than a lowe...