Diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate is photochemically dissociated to give 9,10-dimethoxyanthracene-2-sulfonic acid. The dissociation is considered to proceed via an intra-ion-pair electron transfer from 9,10-dimethoxyanthracene moiety to iodonium moiety. The counteranion acts as both spectral sensitizer for diphenyliodonium ion and precursor for photo-acid generator.
Polarized infrared spectra of polytetrahydrofuran, polytetrahydrofuran-3, 3,4, 4-a4, and poly tetrahydrofuran-ds have been measured in the region from 4000 to 400 em-I. The selection rules for poly tetrahydrofuran molecule are derived under the factor group isomorphous to D2/I. The normal vibrations of these polymer molecules are calculated for the infrared active Btu, B2u, and Bau species, by the use of the GF matrix method with the Urey-Bradley force field. The results show fairly good agreement of the observed and calculated frequencies, and give support to the 21 helix conformation, i.e., the planar zigzag conformation, reported previously. The assignments of the bands are given and discussed.
In a positive photoresist composed of diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate as a novel photoacid generator, bisphenol A protected with tertbutoxycarbonyl group as a dissolution inhibitor, and a novolak resist matrix, the efficiency of photo-acid generation and deprotective reaction were investigated by means of UV-visible and IR spectroscopies. The quantitative measurement of photogenerated acid by using the acid-sensitive dye exhibited 0.18 as the quantum yield of acid generation in novolak resin film. The lithographic evaluation of this system as a chemically amplified resist was studied. The catalytic chain length for the acidcatalyzed deprotection step was determined as about 100 when 10 min post-exposure bake (PEB) at 80°C was given. The sensitivity and the resolution as a positive resist are 180 mJ/cm2 and higher than 1 p m , respectively under the PEB conditions mentioned above.
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