Polyhedral oligomeric silsesquioxane (POSS) based materials hold great promise for developing a photopatternable low-k material which eliminates the need for sacrificial layers when patterning low-k dielectric films. In this work we demonstrate that organic materials based on partially fluorinated, polyhedral oligomeric silsesquioxane (PUSS) functionalized (meth)acrylates (POSS-F) containing appropriate amounts of the photoacid generator (PAG), triphenylsulfonium perfluorooctylsulfonate (TPS-PFOS), in order to achieve positive tone imaging, present ultra low k- values (lower than 2.0) which further decrease when the amount of the photoacid generator increases due to the large percentage of C-F bonds in the selected PAG. A concentration of about 5% w/w of the photo-acid generator was found to be optimal in order to obtain both acceptable photolithographic behaviour and ultra low-k properties. (C) 2012 Elsevier B.V. All rights reserved.