This invention provides a process for making an insulation layer for use in microelectronic devices, whereby capacitive coupling and propagation delay in the microelectronic devices are reduced. This invention can include the formation of a stable solution of nanometer-scale particles consisting of an inorganic core 10 that is decorated with a known number of fullerene molecules 20, and including a soluble component that can act to bind the particles together into an integral structure. This solution can be applied to a microelectronic substrate, and dried to form a continuous, porous layer. Porous layers formed by the process of this invention possess a very low dielectric constant, and can be produced using equipment and techniques common and available to those skilled in the art of microelectronic fabrication.