A negative working and chemically amplified photosensitive polymer has been developed, which is based on poly(2,6-dihydroxy-1,5-naphthalene) (PDHN), the crosslinker 4,4'-methylenebis [2,6-bis(hydroxymethyl)] phenol, and the photoacid generator (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile. PDHN, with a number-average molecular weight of 25,000, was prepared by the oxidative coupling polymerization of 2,6-dihydroxynaphthalene with di-mu-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride in 2-methoxyethanol at room temperature. The resulting PDHN showed a 5% weight loss temperature of 440 degreesC in nitrogen and a low dielectric constant of 2.82. The resist showed a sensitivity of 8.3 mJ cm(-2) and a contrast of 11 when it was exposed to 436-nm light, followed by postexposure baking at 100 degreesC for 5 min and development with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 degreesC. A fine negative image featuring 10-mum line-and-space patterns was obtained on a film 3 mum thick exposed to 10 mJ cm(-2) of ultraviolet light at 436 nm in the contact-printed mode. (C) 2004 Wiley Periodicals, Inc.