The effect of epoxy-based cross-linking additives with different functionalities on the photolithographic properties, adhesion to substrates, and cross-link density of a tetramethyl ammonium hydroxide-developable polynorbornene-based dielectric was investigated. Three different multifunctional epoxy additives were investigated: difunctional, trifunctional, and tetrafunctional compounds. It was found that incorporation of a small quantity (1 wt % of solution) of an ultraviolet-absorbing tetrafunctional cross-linker, tetraphenylol ethane tetraglycidyl ether, activated the photo-catalyst and improved the sensitivity of a previously photosensitive polynorbornene-based formulation by a factor of 3.7. The impact of the epoxy cross-linkers on the physical and optical properties of the polymer formulations was evaluated. The contrast was improved from 7.37, for the control formulation, to 24.2. The polymer-to-substrate adhesion was also improved by addition of the tetrafunctional epoxy cross-linker, which facilitates the development of high-aspect-ratio structures. Hollow-core pillar structures in 40-mu m-thick films with a depth-to-width aspect ratio of 13 : 1 were produced. The cross-link density was studied by using swelling measurements of cured films to evaluate the average molecular weight between cross-links. (c) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1916-1925, 2011