A method and apparatus for removing excess
dopant from a doped substrate is provided. In one embodiment, a substrate is doped by surfaced deposition of
dopant followed by formation of a capping layer and thermal
diffusion drive-in. A reactive etchant mixture is provided to the process chamber, with optional
plasma, to etch away the capping layer and form volatile compounds by reacting with excess
dopant. In another embodiment, a substrate is doped by energetic implantation of dopant. A
reactive gas mixture is provided to the process chamber, with optional
plasma, to remove excess dopant adsorbed on the surface and high-concentration dopant near the surface by reacting with the dopant to form volatile compounds. The
reactive gas mixture may be provided during
thermal treatment, or it may be provided before or after at temperatures different from the
thermal treatment temperature. The volatile compounds are removed. Substrates so treated do not form toxic compounds when stored or transported outside
process equipment.