Development of isosorbide-derived, biobased, and photosensitive poly(ether imides) for negative-type photoresists using a photobase generator

Abstract Biobased photosensitive polyimides (PSPIs) that simultaneously exhibit low dielectric properties, high thermal stability, and reliable photolithographic performance are highly desirable for advanced microelectronic and packaging applications. In this study, a negative-type PSPI system is developed using an isosorbide-derived diamine and aromatic dianhydrides to form biobased poly(ether imides). Photosensitivity is introduced by incorporating a photobase generator into the corresponding poly(amic acid) precursor, enabling alkaline development through base-catalyzed imidization upon i -line (365 nm) exposure. Poly(ether imides) are expected to be stable during base development in photopatterning and lithography. As a result of the incorporation of alicyclic isosorbide units and ether linkages, the poly(ether imides) show low dielectric constants ( < 3.0) and dissipation factors ( < 0.01) in the GHz frequency range, satisfying typical requirements for high-frequency microelectronic applications. Among the investigated systems, the biobased poly(ether imides) exhibit distinct trade-offs in terms of optical transparency, dielectric performance, and alkaline resistance. Lithographic evaluation reveals that the optimized biobased PSPI system enables stable negative-type patterning with well-defined line-and-space features in the tens of µ m range while maintaining film thicknesses exceeding 1 µ m. These results demonstrate that the biobased poly(ether imide) system offers a promising molecular design strategy for sustainable, low-dielectric PSPI suitable for advanced microfabrication processes.