A novel photosensitive silicone ladder polymer: Synthesis, photochemical, and thermal characteristics

A negative working photosensitive silicone ladder polymer (PVSQ) based on p olyphenylsilsesquioxane with vinyl groups as a reactive substituents in the side chain, and 2,6-bis(azidobenzylidene)-4-methylcyclohexanone (BA) as a photocrosslinker, has been developed. The monodisperse PVSQ was synthesized by co-polymerization of trichlorophenylsilane and trichloro(vinyl)silane w ith potassium hydroxide in isobutyl methyl ketone. The PVSQ film showed exc ellent transparency above 280 nm and high solubility in organic solvents. T he photosensitive PVSQ containing 3 wt% of BA showed the sensitivity of 40 mJ cm(-2) when it was exposed to 365 nm light (i-line) followed by developm ent with a mixture solution of anisole and xylene at 25 degreesC. The photo sensitive PVSQ film also showed high thermal stability (decomposition tempe rature: 520 degreesC) and low dielectric constant (3.2/1 MHz), demonstratin g a high potential for application to LSI production.