Processing method

Abstract

A processing method includes disposing a workpiece having a processed surface in a processing solution, disposing a photocatalyst film in the processing solution opposite the processed surface, irradiating the photocatalyst film with a light, so as to generate active species from the processing solution by a photocatalytic action of the photocatalyst film, controlling a diffusion distance of the active species in the processing solution by a radical scavenger added to the processing solution, and chemically reacting the active species with surface atoms of the processed surface and generating a chemical compound to be eluted in the processing solution, so as to process the workpiece.

1 . A processing method comprising:
 disposing a workpiece having a processed surface in a processing solution,   disposing a photocatalyst film in the processing solution opposite the processed surface,   irradiating the photocatalyst film with a light, so as to generate active species from the processing solution by a photocatalytic action of the photocatalyst film,   controlling a diffusion distance of the active species in the processing solution by a radical scavenger added to the processing solution, and   chemically reacting the active species with surface atoms of the processed surface and generating a chemical compound to be eluted in the processing solution, so as to process the workpiece.   
     
     
         2 . The processing method according to  claim 1 , wherein the workpiece is processed by controlling a temperature of at least one member selected from the group consisting of the photocatalyst film, the workpiece and the processing solution. 
     
     
         3 . The processing method according to  claim 1 , wherein the radical scavenger comprises a protic organic compound. 
     
     
         4 . The processing method according to  claim 3  wherein the protic organic compound comprises one of methanol, ethanol, propanol and butanol, or a mixture liquid of not less than two selected therefrom. 
     
     
         5 . The processing method according to  claim 1 , wherein the photocatalyst film comprises a film of TiO 2 , and the TiO 2  comprises an anatase-type crystal or a rutile-type crystal, or a mixed crystal of the anatase-type crystal and the rutile-type crystal. 
     
     
         6 . The processing method according to  claim 1 , wherein the light has a wavelength of not more than 420 nm. 
     
     
         7 . The processing method according to  claim 1 , wherein the photocatalyst film is disposed on a substrate formed of quartz or glass. 
     
     
         8 . The processing method according to  claim 7  wherein the light is irradiated from a side of the substrate toward the photocatalyst film, so as to generate active species. 
     
     
         9 . The processing method according to  claim 1 , wherein the workpiece disposed in the processing solution comprises at least one material selected from the group consisting of SiC, GaN, sapphire, ruby and diamond.