Synthesis and characterization of aqueous base developable negative-tone poly(imide-amic acid) copolymers by the effect of the imidization ratio

AbstractNegative-tone photosensitive poly(imide-amic acid) (PIA) copolymers were synthesized from a chemical imidization process using poly(amic acid) that was prepared from a polycondensation reaction of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 4,4′-oxydianiline (ODA), and di[2-(methacryloyloxy)ethyl]-5-aminoisophthalate (Di-HEMA-AP) with photoreactive acrylate groups. The imidization ratio was controlled by the reaction time, and the synthesized PIA copolymers were investigated using spectroscopic methods. The photolithographic behaviors of the formulations composed of PAA and PIA copolymers, Michler’s Ketone (MK), and crosslinker were evaluated using a 2.38 wt. % tetramethylammonium hydroxide (TMAH) solution. The solubility decreased with increasing imidization ratio in an alkaline base solution because of the reducing content of carboxylic acid groups in the polymer main chain. The formulations from PIA copolymers gave clear patterns without distortion by UV light i-line irradiation and followed 2.38 wt. % TMAH solution development.Keywords: Alkaline developerchemical imidizationnegative-tone photoresistpoly(amic acid)poly(imide-amic acid) (PIA) copolymers Additional informationFundingThis study was supported by Yeungnam University Research Grants in 2021 and a “Human Resources Program in Energy Technology” of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resources from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20204010600100).