Photopatterning of Thiol-ene-Acrylate Copolymers

Thiol-ene-acrylate copolymers exhibit a unique blend of characteristics which make them suitable for both photolithographic patterning and material property tuning. Five thiol-ene-acrylate monomer blends are found to exhibit similar reaction rates via photo-differential scanning calorimetry, while dynamic mechanical analysis shows the trend in the thermomechanical properties of three of the systems. Two selected thiol-ene-acrylate systems showed rapid polymerization with low apparent shrinkage and relatively low heat evolution (when compared to acrylates) with excellent patternability, while a binary acrylate system shows extreme apparent shrinkage, greater heat evolution, and does not replicate the mask pattern in a controllable fashion. The apparent shrinkage is a measure of patternability, since this quantity represents the actual polymer dimensions when compared to the desired dimension (i.e., photomask pattern).