An apparatus and a method of cleaning a dielectric film are provided in the present invention. In one embodiment, an apparatus of cleaning a dielectric film the apparatus includes a chamber body adapted to support a substrate therein, a remote plasma source adapted to provide a plurality of reactive radicals to the chamber body, a passage coupling the remote plasma source to the chamber body, and at least one magnet disposed adjacent the passage. In another embodiment, a method of cleaning a dielectric film that includes providing a substrate having an at least partially exposed dielectric layer disposed in a process chamber, generating a plurality of reactive radicals in a remote plasma source, flowing the reactive radicals from the remote plasma source into the process chamber through a passage having at least one magnet disposed adjacent the passage, and magnetically filtering the reactive radicals passing through the passage.