A method of fabricating a semiconductor device begins by forming a lower interconnection dielectric on a substrate and forming at least one active or passive device in the lower interconnection dielectric. Apparatus for carrying out the method is disclosed. The treating gas or hydrogen is directed to a subsurface site that includes one or more contaminants, thereby stimulating anaerobic degradation of the subsurface contaminants. From the initial phase obtained by the applied mask, the PN generator is then slewed to the start of the search window.