Solid surface smoothing method

Abstract

In a method of irradiating a gas cluster ion beam on a solid surface and smoothing the solid surface, the angle formed between the solid surface and the gas cluster ion beam is chosen to be between 1° and an angle less than 30°. In case the solid surface is relatively rough, the processing efficiency is raised by first irradiating a beam at an irradiation angle θ chosen to be something like 90° as a first step, and subsequently at an irradiation angle θ chosen to be 1° to less than 30° as a second step. Alternatively, the set of the aforementioned first step and second step is repeated several times.

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         14 . A method of smoothing a solid surface by etching the solid surface with a gas cluster ion beam, comprising:
 a) irradiating the solid surface with the gas cluster ion beam with an irradiation angle between the solid surface and the gas cluster ion beam being equal to or greater than 30°; and   b) irradiating, after step a), the solid surface with the gas cluster ion beam with the irradiation angle being less than 30°.   
     
     
         15 . A method of smoothing a solid surface by etching the solid surface with a gas cluster ion beam, comprising:
 a) irradiating the solid surface with the gas cluster ion beam with a first irradiation angle between the solid surface and the gas cluster ion beam being less than 30°;   b) irradiating the solid surface with the gas cluster ion beam with a second irradiation angle between the solid surface and the gas cluster ion beam being equal to or greater than 30°; and   c) repeating one or more times a continuous change of an irradiation angle between the first irradiation angle and the second irradiation angle while irradiating the solid surface with the gas cluster ion beam.   
     
     
         16 . A method of smoothing a solid surface by etching the solid surface with a gas cluster ion beam, comprising:
 a) irradiating the solid surface with the gas cluster ion beam in a first direction with an irradiation angle between the solid surface and the gas cluster ion beam being less than 30°, wherein the first direction is defined by a projection of the gas cluster ion beam onto a plane defined by the solid surface; and   b) irradiating the solid surface with the gas cluster ion beam in a second direction with an irradiation angle between the solid surface and the gas cluster ion beam being less than 30°, wherein the second direction is defined by a projection of the gas cluster ion beam onto the plane and the second direction is different from the first direction.   
     
     
         17 . The method of  claim 16  comprising varying the direction continuously back and forth between the first direction and the second direction while irradiating the solid surface with the gas cluster ion beam. 
     
     
         18 . The method according to  claim 17 , wherein the irradiation angle between the gas cluster ion beam and the solid surface is fixed during step a). 
     
     
         19 . The method of  claim 16 , wherein the second direction is 5° or more away from the first direction. 
     
     
         20 . The method according to  claim 19 , wherein the irradiation angle between the gas cluster ion beam and the solid surface is fixed during step a). 
     
     
         21 . The method according to  claim 14 , wherein the solid surface is a side wall surface of a concave structure or a convex structure. 
     
     
         22 . The method according to  claim 15 , wherein the solid surface is a side wall surface of a concave structure or a convex structure. 
     
     
         23 . The method according to  claim 17 , wherein the solid surface is a side wall surface of a concave structure or a convex structure. 
     
     
         24 . The method according to  claim 19 , wherein the solid surface is a side wall surface of a concave structure or a convex structure. 
     
     
         25 . A method of smoothing a solid surface by etching the solid surface with a gas cluster ion beam, comprising:
 a step of irradiating the solid surface with the gas cluster ion beam with an irradiation angle between the solid surface and the gas cluster ion beam being less than 30° for at least a portion of a time period of a gas cluster ion beam irradiation, wherein the solid is a thermal oxide film formed on a substrate.