Dry cleaning for Fe contaminants on Si and SiO2 surfaces with silicon chlorides

While investigating the surface dependence of the dry cleaning technique using Cl radicals generated with UV irradiation (UV/Cl-2), we found that silicon chlorides [SiClchi (chi = 1 to 4)], etching products created from a reaction between Si and Cl radicals, can remove Fe contaminants. SiCl4 gas removes Fe contaminants existing on both Si and SiO2 surfaces without surface dependence. The surface residue due to the adsorption of SiCl4 is insignificant. We also found that a small addition of Cl-2 to SiCl4 is advantageous for dry cleaning Si surfaces. Surface flatness and composition are maintained after cleaning with Cl-2 + SiCl4 (5:195. ml/min) gas mixture. Dry cleaning technology has been significantly improved by the use of an SiCl4-based system instead of Cl-2 alone.