a cleanling apparatus for removing contaminants from the surface of a substrate includes two parts : one which produces an aerosol including frozen particles and directs the aerosol onto the surface of the substrate to remove contaminants from the surface by physical force , and another part in which a fluid including a gaseous reactant is directed onto the surface of the substrate while the surface is irradiated to cause a chemical reaction between the reactant and organic contaminants on the surface , to chemically removing the organic contaminants . in the method of cleaning the substrate , the physical and chemical cleaning processes are carried out in a separate manner from one another so that the frozen particles of the aerosol are not exposed to the effects of the light used in irradiating the surface of the substrate . therefore , the effectiveness of the aerosol in cleaning the substrate is maximized .