A new photoresist based on hyperbranched poly(arylene ether phosphine oxide)

Hydroxy-terminated hyperbranched poly(arylene ether phosphine oxide) (P2) was synthesized via nucleophilic aromatic substitution reaction of AB₂ monomer, bis(4-hydroxyphenyl)-4′-fluorophenylphosphine oxide with K₂CO₃ as a base in NMP. The obtained polymer was dissolved well in NMP and DMSO, and casting of the solution gave a transparent film. The study on dissolution behavior of the film containing 10 wt% of diphenyliodonium-9,10-dimethoxyanthracene-2-sulfonate (DIAS) as a photoacid generator and 25 wt% of 4,4′-methylenebis-[2,6-bis(hydroxymethylphenyl) phenol] (MBHP) as a cross linker revealed that 0.5 wt% aqueous tetramthylammonium hydroxide (TMAH) solution was a suitable developer for this negative-type photoresist system. The photoresist system containing 10 wt% of DIAS and 25 wt% of MBHP showed the sensitivity of 9 mJ/cm² and the contrast of 1.6 when it was exposed to 365 nm light and postbaked at 120°C, followed by developing with 0.5 wt% aqueous TMAH solution at room temperature. The heat-treated (300°C, 30 min) negative image did not show any distortion.