Method of manufacturing semiconductor device and methods of processing,

Abstract

The gate oxide film is prevented from being thinned partially. The semiconductor substrate (wafer) can be etched (processed) under excellent conditions. The impurities on the wafer surface can be analyzed and further reduced. In the first aspect, the substrate is irradiated with ultraviolet rays in contact with an F-containing aqueous solution, so that the oxide film and the substrate can be etched at roughly the same etching speed under excellent controllability without deteriorating the planarization of the substrate. In the second aspect, the substrate is etched by irradiating ultraviolet rays during exposure to an acid aqueous solution, so that surface metallic contamination and particles can be removed without deteriorating the wafer surface roughness. Further, the impurity elements in the outermost surface layer of the wafer can be analyzed at high precision by analyzing elements contained in the acid aqueous solution used for the etching. According to the third aspect, holes and electrons are recombined in the polycrystal silicon during irradiation of the ultraviolet rays, and metallic impurities are dissolved into the aqueous solution as ions, so that metallic impurities in the polycrystal silicon can be reduced.