Novel low‐temperature curable photosensitive polyimides with stable storage

Abstract In this work, varieties of thermal base generators with nitrogen heterocyclic bases as curing catalysts were synthesized and further blended with photo‐crosslinking agents, and photoinitiators to achieve the research goal of the low‐temperature curable negative photosensitive polyimide (n‐LTPI) photoresist. Due to the addition of thermal base generators, the curing temperature was reduced to 200 °C. Adding 2% 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) pyromellitic acid salt to the photoresist can completely iminate at 200 °C. Through field‐emission scanning electron microscope analysis, the film produced high‐quality photo‐patterns with line and via resolution of 2–5 μm at 5–6 μm film thickness. Compared with existing technologies, our article not only achieves low‐temperature curing of photoresists but also improved storage stability, which has great practical value in the field of advanced semiconductor packaging.