Modification Pathways for Copoly(2-oxazoline)s Enabling Their Application as Antireflective Coatings in Photolithography

Chromophore-functionalized copoly(2-oxazoline)s are successfully evaluated as bottom antireflective coatings (BARCs) in high-resolution photolithography. With respect to UV light sources used in photolithographic production routines, anthracene is chosen as a chromophore. For application as polymer in BARCs, the copolymer poly(2-ethyl-2-oxazolin)₄₅-stat-poly(2-dec-9′-enyl-2-oxazolin)₂₀-stat-poly(2-(3′-(1″-(anthracen-9-ylmethyl)-1″,2″,3″-triazol-4-yl)propyl)-2-oxazolin)₃₅ can be synthesized by the Huisgen cycloaddition click reaction of the copolymer poly(2-ethyl-2-oxazolin)₄₅-stat-poly(2-dec-9′-enyl-2-oxazolin)₂₀-stat-poly(2-pent-4′-inyl-2-oxazolin)₃₅ and the corresponding azide-functionalized anthracenes. These copolymers can be crosslinked by the thermally induced thiol-ene reaction involving the unsaturated C=C bonds of the poly(2-dec-9′-enyl-2-oxazoline) repetition units and a multifunctional thiol as crosslinker. Tests of this BARC in a clean room under production conditions reveal a significant decrease of the swing-curve of a chemically amplified positive photoresist by more than 50%, hence significantly increasing the resolution of the photoresist.