High-Modulus Positive-type Photosensitive Poly(amide-benzoxazole)s

Abstract

A new type of high modulus poly(amide benzoxazole)s (PABO) was derived from trans-1,4-cyclohexanedicarboxylic acid (CHDCA), bis(3-hydroxy-4-amino) biphenyl (p-HAB), bis(4-hydroxy-3-amino)biphenyl (m-HAB), and 2,2'-bis(trifluoromethyl) benzidine (TFMB). A stiff structure of cycloaliphatic CHDCA and fluorine-containing rod-like TFMB play a great role for the generation of high modulus in the PABO films with a significantly improved transparency at 365 nm for the PABO precursor film. A PABO possessing a copolymer composition of m-HAB60, TFMB40, and CHDCA100 achieved a high modulus of 4.9 GPa, a low coefficient of thermal expansion (CTE) of 19.8 ppm/K, a high Tg at 294°C, sufficient film toughness (elongation at break = 12.5 %), and high transparency at 365 nm (light transmittance = 73 %) for a 10 ?m thick PABO precursor film. The molecular weight control allowed the formation of fine positive-tone patterns by development using a 2.38 wt% TMAH aqueous solution at room temperature.