A negative type photosensitive polymer based on poly(naphthylene ether), a cross-linker, and a photoacid generator with low dielectric constant

A novel negative-working thermally stable photosensitive polymer based on poly(naphthylene ether), a cross-linker hexa(methoxymethyl)melamine, and a photoacid generator (5-propylsulfonyl-oxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile. Poly (naphthylene ether) was prepared via the oxidative coupling polymerization of 4,4'-bis(1-naphthyloxy)-2,2'-dimethylbiphenyl. This photosensitive polymer showed a high sensitivity (D-0.5) of 6.0 mJ cm(-2) and a high contrast (gamma(0.5)) of 5.2, when it was exposed to a 436 nm light, post-exposure baked at 140 C for 5 min, and developed with toluene. A negative image featuring 20 pm line and space patterns was obtained on a film exposed to 20 mJ cm(-2) of visible light at 436 nm by the contact-printed mode. The resulting polymer film had the low dielectric constant of 2.8 and high thermal stability.