Photo patternable porous siloxane thin films using cyclodextrins as template materials

Photo patternable cyclic silsesquioxane (mCSSQ) compositions containing heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (tCD) as a porogen and photo acid generator (PAG) have been prepared, with the goal of achieving a photo resist free porous low dielectric constant precursor. The composition containing triphenylsulfonium based PAG could effectively create a patterned mCSSQ thin film with a resolution approaching ∼2 μm. The pore size of the mCSSQ film with PAG was smaller than that without PAG. Furthermore, the pore size distribution of the mCSSQ film with PAG was much narrower than that without PAG. This might be attributed to the disturbance effect of the agglomeration of tCD molecules through pre-vitrification of the matrix at the relatively low curing temperature. The mechanical property and dielectric constant of the photo-definable mCSSQ/tCD/PAG film were comparable to those of the mCSSQ/tCD counterpart.