Copoly(2-oxazoline)-based photoresists from renewable resources.
Résumé
Facing the challenges of the on-going trend to high-technol. applications with decreased feature sizes, the development of novel photoresists has become a major factor within this area of research. Neg. photoresists reproduce geometric patterns commonly by the crosslinking of polymers, yielding insol. 2.5-dimensional surface structures. Proceeding our work on the formulation of a water-developable photoresist, we hereby present the latest addn. of our toolbox of 2-oxazoline-based photoresists by a photoresist derived from renewable resources . The monomers to be used for the microwave-assisted synthesis of the copolymer were synthesized from undecenoic acid (castor oil) and decanoic acid (coconut oil) and ethanol amine in one-step solvent-free reactions. The copolymn. itself was performed in consideration of energy efficiency at a scale of 300 g under microwave irradn. in ionic liqs. The copolymer pptd. upon cooling, enabling for the fast recovery of the product and the ionic liq. with yields over 95%. The photoresist could be formulated (and developed) in Et lactate . Croslinking of the copolymer was realized by UV-induced thiol-ene reactions of the polymer and a tetrathiol, providing resolns. of 1 mm at a film height of 100 nm. [on SciFinder(R)]