Polyurethane (PU) monomer mixtures containing commercially available o‐nitrobenzyl‐based photocleavable monomers have been formulated and tested as low‐cost positive tone photoresists. The photolysis reaction is studied by UV spectroscopy. Well‐defined micropatterns on 2 μm thick photodegradable PU films are obtained using 365 nm light exposure. This strategy is also extended to improved formulations based on synthesized o‐nitrobiphenylpropyl derivatives with enhanced photochemical properties for single photon excitation and high two‐photon absorption cross‐sections. Improved pattern resolution in 2D and the capability of 3D resolution using a scanning laser at 780 nm is demonstrated. This work demonstrates the potential of PUs as readily available, versatile, and easy‐to‐use photoresist materials for low‐cost lithography applications.
