Parylene VIPTM AF-4 dielectric is a potential low εR candidate for ULSI manufacture. The search for new IMD materials with low dielectric constant (k ≤ 2.5) to enable sub 0.18 micron technologies is focusing on new polymers, deposited by either spinning or CVD methods. Two classes of requirements have to be satisfied for a material to be successful, i.e., used in volume device manufacturing. First, a set of physical characteristics have to be met, among the most important are thermal stability above 400 °C, mechanical stability, and good adhesion to a variety of substrates. Then, a second set of more stringent requirements have to be met related to device integration. For example, electrical performance in a device and dry etching for via formation. We report results on the evaluation of Parylene AF-4, deposited by vapor-deposition polymerization of tetrafluoro-p-xylylene. We present data on deposition characteristics, film composition and purity, thermal stability as well as preliminary electrical data.