| Abstract: | A new positive‐working polyimide having photosensitive o‐nitrobenzyl ester group as side substituent, poly{1,4‐phenyleneoxy‐1,4‐phenylene‐3,6‐di[4‐(o‐nitrobenzyloxy)carbonylphenyl]pyromellitimide} (ODA‐PI‐Nb), was prepared and its aqueous alkali‐developability and photosensitivity were investigated. ODA‐PI‐Nb was synthesized by the esterification reaction of poly[1,4‐phenyleneoxy‐1.4‐phenylene‐3,6‐di(4‐carboxylphenyl)pyromellit imide] (ODA‐PI) with o‐nitrobenzyl bromide in the presence of triethylamine (Et3N). ODA‐PI‐Nb obtained was characterized by FT‐IR and 1H‐NMR spectroscopy. The degree of esterification reaction was found from 1H‐NMR absorption of CH2 proton to be over 95 mol%. Upon photo‐irradiation ODA‐PI‐Nb transformed to the freely aqueous alkali‐soluble ODA‐PI under formation of o‐nitrosobenzaldehyde. The thickness loss of thin ODA‐PI‐Nb films upon post‐baking at 400°C was in the 10–15% range. ODA‐PI‐Nb showed positive‐tone behavior in characteristic sensitivity curve and positive patterns were obtained using a typical lithographic process using aqueous tetramethylammonium hydroxide developer. The patterns with excellent resolution were observed and evaluated by optical microscopy and scanning electron microscopy. Copyright © 2005 John Wiley & Sons, Ltd. |
