ABSTRACT
Abstract A novel thermally stable negative-working photodefinable material which employs a chemical amplification system based on acid catalyzed cross-linking has been proposed. We chose methylol type cross-linkers for the system since their photopolymerization proceeds efficiently even under mild acidic conditions. Focusing on the dissolution behavior study, we optimized the composition, which afforded high dissolution contrast and fast dissolution rate for thick films fabrication. Photolithographic evaluations of the material revealed that the sensitivity was less than 100 mJ/cm2 for a 7-µm-thick film, which is better than that of reported positive systems. Subsequent detailed evaluations showed a high performance such as a fine linear correlation between the mask size and the fabricated pattern and critical dimension uniformity (standard deviation = 0.15). In addition, we demonstrated thicker film fabrication (>10 µm). Consequently, appropriate pattern profiles were obtained. Finally, this newly designed material showed sufficiently high film properties, which are comparable to those of a conventional non-photodefinable polyimide.
