Process for removing organic materials during formation of a metal interconnect

A method for removing organic material from an opening in a low k dielectric layer and above a metal layer on a substrate is disclosed. An ozone water solution comprised of one or more additives such as hydroxylamine or an ammonium salt is applied as a spray or by immersion. A chelating agent may be added to protect the metal layer from oxidation. A diketone may be added to the ozone water solution or applied in a gas or liquid phase in a subsequent step to remove any metal oxide that forms during the ozone treatment. A supercritical fluid mixture that includes CO2 and ozone can be used to remove organic residues that are not easily stripped by one of the aforementioned liquid solutions. The removal method prevents changes in the dielectric constant and refractive index of the low k dielectric layer and cleanly removes residues which improve device performance.