| 초록 |
PMSSQ (poly methylsilsesquioxane) that is often used as matrix for application of low-k film is known to be composed of the various molecular structures, typically such as cagelike and ladderlike structure. In this study, thin films were prepared from cagelike PMSSQ and MTMS-BTMSE (9:1) copolymer. Cage-like PMSSQ was separated by fractional crystallization method in mixed solution of hexane and chloroform. It is observed that refractive indices decrease with incorporated cage-like species, which is believed to be due to the formation of more free-volume in cured films. UV treatment is utilized to maintain cage-like structure further in silsesquioxane matrix, because cagelike structure can be easily deformed to ladderlike structure or sublimated in curing process. It is interesting to note that refractive indices of UV assisted thin films is clearly lowered than those of non-treated films due to the increase of free volume by the formation of more cage-like structures, as evidenced by FT-IR measurements. |
