Positive Tone, Polynorbornene Dielectric Crosslinking
Author(s)
Schwartz, Jared M.
Mueller, Brennen K.
Elce, Edmund
Pritchard, Zachary D.
Li, Helen W.
Grillo, Angelica M.
Lee, Sang Y.
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Abstract
The processing and properties of a positive-tone, aqueous develop, epoxy crosslinked permanent dielectric based on a polynorbornene
(PNB) backbone and bis(diazonaphthoquinone) (DNQ) photosensitive compound were investigated. The developing and cure
properties of the films were studied as a function of cure temperature, epoxy crosslinker loading and DNQ loading. Reduced
modulus measurements showed that crosslinking of the polymer film occurred via reaction of the polymer with DNQ. The final
modulus of the DNQ-crosslinked film was 4.0 GPa. Swelling measurements for a UV exposed film showed material leaching from
the film. Residual solvent from swelling measurements was analysed by gel permeation chromatography which showed the indene
carboxylic acid form of DNQ leached out of the polymer film. The unexposed film did not exhibit material loss through leaching.
When developed, films showed a decline in modulus to 2.6 GPa, likely due to the reaction of DNQ with the aqueous base developer
forming nonreactive byproducts that did not contribute to crosslinking. An epoxy crosslinker was added to the formulation which
helped crosslink the polymer film by inhibiting uptake of the aqueous base during developing. The epoxy inhibition of the base
uptake was confirmed by quartz crystal microbalance, where an increase in epoxy loading led to a decrease in base uptake of the
film during developing. 19F-NMR results support the DNQ-PNB crosslinking through esterification. Electrical characterization of
the cured PNB films showed a relative dielectric constant of 3.65 for a DNQ and epoxy containing film after curing at 220◦C.
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Date
2014-05
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This work is licensed under Creative Commons Attribution (unported, v4.0) License.