conventional explanation is that the smaller size of these
resists compared to conventional polymeric resists results in
higher resolution features through smaller pixel sizes. Several
groups3,28 have examined the LER obtained using polymeric
resists, and showed that even a 12 fold increase in Mw
(from 2.9–33.5 kg mol21) does not affect LER, which
suggests molecular size alone is not the complete explanation.
One significant difference between molecular glass resists
and polymeric resists is polydispersity. Molecular glass
resists are monodisperse, compared to polymer resists which
always consist of a range of molecular weights. Lower
molecular weight polymers have faster dissolution rates
compared to higher molecular weight samples.3 This implies
that the dissolution behavior of a polymeric resist upon
development is a composite value depending on it molecular
weight distribution and degree of deprotection, which leads
to higher values of LER. We hypothesise that monodisperse
MG resists, in which dissolution rate should be comparatively
constant across the exposed regions of the sample, develop
in a more homogenous manner and hence return lower values
of LER.
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Acknowledgements
We thank Intel Corporation for making this work possible
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1474 | J. Mater. Chem., 2006, 16, 1470–1474
This journal is ß The Royal Society of Chemistry 2006