Recent progress in negative-working photosensitive and thermally stable polymers

The production of semiconductors, especially for semiconductor large-scale integration (LSI), has been definitely supported by photolithographic technologies using photosensitive polymers in the micro-electronic device industry. Among them, photosensitive and thermally-stable polymers (PSTSPs) provide simpler resist system than the conventional one, in which the resist materials stays after forming a pattern and function as thermally resisting insulators in integrated circuits (ICs) and multi-chip packages (MCPs), eliminating the extra process of resist removal. Recently, negative-working chemical amplification photoresists have started to receive much attention as quite simple and direct network formation systems in polymer films. The recent progress in negative-working PSTSPs based on the chemical amplification system is summarized in this review article, which includes low dielectric constant polymers for LSI, high refractive index polymers for microlens materials in complementary metal oxide semiconductor image sensors, novolac resists for indium tin oxide patterning, and poly(3-hexylthiophene) for organic field-effect transistors.