A method of modifying the porosity of a thickness of a layer of porous dielectric material having a surface and formed on a semiconductor substrate is provided by exposing the porous dielectric material to a sufficient temperature in the presence of a first gas to drive moisture particles out of the pores. Modifying also includes, exposing the porous dielectric material to a radio frequency stimulus of sufficient power in the presence of a second gas to densify a thickness of the porous dielectric material to reduce or prohibit subsequent absorption of moisture or reactant gas particles by the thickness or porous dielectric material.