Synthesis and micropatterning properties of a novel base‐soluble, positive‐working, photosensitive polyimide having an o‐nitrobenzyl ether group

Abstract

A novel positive‐working, photosensitive polyimide, poly[1,4‐phenyleneoxy‐1,4‐phenylene‐2,2′‐di(2‐nitrobenzyloxy)benzophenone‐3,3′,4,4′‐tetracarboxdiimide] (OPI‐Nb), developable with an aqueous base was prepared by the o‐nitrobenzylation of a polyimide, poly(1,4‐phenyleneoxy‐1,4‐phenylene‐2,2′‐dihydroxybenzophenone‐3,3′,4,4′‐tetracarboxdiimide) (OPI), derived from 2,2′‐dihydroxy‐3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (DHBA) and 4,4′‐oxydianiline, and it micropatterning properties were investigated. The o‐nitrobenzylation of OPI to OPI‐Nb was conducted with o‐nitrobenzyl bromide in N‐methyl‐2‐pyrrolidinone containing Et3N. The DHBA monomer was synthesized by exhaustive KMnO4 oxidation of bis(2‐dimethoxy‐3,4‐dimethylphenyl)methane obtained by etherification of bis(2‐hydroxy‐3,4‐dimethylphenyl)methane with iodomethane, followed by deprotection of the methoxy groups and cyclodehydration of the obtained 2,2′‐dihydroxy‐3,3′4,4′‐benzophenonetetracarboxylic acid. The intermediate bis(2‐hydroxy‐3,4‐dimethylphenyl)methane was prepared by the condensation of 2,3‐dimethylphenol with paraformaldehyde. The degree of o‐nitrobenzylation was determined to be over 94 mol % from 1H NMR absorption of benzylic CH2 protons. The aromatic OPI was perfectly soluble in a dilute aqueous NaOH solution and tetramethylammonium hydroxide (TMAH), whereas OPI‐Nb was not even swellable in them. In the micropatterning process, OPI‐Nb showed a line‐width resolution of 0.4‐μm and a sensitivity of 5.4 J/cm2 when its thin films were irradiated with 365‐nm light and developed with a 2.38% aqueous TMAH solution at room temperature for 90 s. The thickness loss of OPI‐Nb films measured after postbaking at 350 °C was in the 8–9% range. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 776–788, 2007

Synthesis and Characterizations of Positive-Working Photosensitive Polyimides Having 4,5-Dimethoxy-o-Nitrobenzyl Side Group

“…In the most of previous works, polyhydroxyimide (PHI) had been used as a base-soluble polyimide backbone for the preparation of positive-working PSPI. [21][22][23] However, in this work, we employed 3,5-diamino benzoic acid (3,5-DABA), a carboxylic acid-functionalized diamine monomer and 6FDA. These monomer pair provided an alkalinesoluble polyimide (PI-CA) with minimum absorption at > 350 nm.…”

“…UV-decomposable polyimide from oxydianiline (ODA) and cyclobutane tetracarboxylic dianhydride was reported by Moore and his coworkers. 19 More recently, PSPIs based on polyhydroxyimide (PHI) having various photo-functional groups such as dispersed DNQ, 20 covalently bonded t-butoxycarbonyl (t-BOC) 21 or o-nitrobenzyl moieties 22,23 have been reported. Hydroxy-functionalized aromatic polyimides were used in these systems for the solubilization of polymer backbone in alkaline developers.…”

Photo-Induced Polarity Change of Photosensitive Polyimide with o-Nitrobenzyl Ester Side Chain

“…Photo irradiation cause deprotection of the o-nitrobenzyl group to generate polar benzoic acid group and resulted polymer is soluble in a developer. Several PSPI systems employing side chain o-nitrobenzyl ester and ether [7,8] for solubility change were reported. However, it is difficult to introduce o-nitrobenzyl group to all side chain because o-nitrobenzyl group was introduced by post-polymerization reaction.…”

Alkaline-developable Positive-type Photosensitive Polyimide based on Fluorinated Poly(amic acid) and Fluorinated Diazonaphthoquinone

“…Polyimides (PIs) are an important class of advanced materials and fulfill the above requirements, therefore, photosensitive PIs (PSPIs), which are formed by the addition of a photosensitizing agent to PIs, have been widely used in the microelectronics fields as a stress buffer and insulation layers. Furthermore, they simplify processing and avoid the use of photoresists in the microelectric industry [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Recently, positive-type PSPIs have been receiving much attention because of their several advantages compared to negative-type PSPIs, such as high resolution due to low swelling during development, and the use of an alkaline aqueous solution as a developer in place of organic developers.…”