Method for removing carbon contamination from optic surfaces

Abstract

A method using atomic hydrogen for removing carbon contamination from optical surfaces. The method is particularly useful for removing carbon and hydrocarbon contamination in-situ from the surface of the multilayer optics used for extreme ultraviolet lithography (EUVL) without degrading the quality of the optical surface. Atomic hydrogen at pressures in the range of about 10 −3 and 10 −4 Torr without the potentially detrimental heating of the optic is used to provide cleaning rates of about 6-60 Å/hr.

We claim:  
     
         1 . A method for removing contaminants from a surface, comprising: 
 providing a vacuum chamber to house the contaminated surface; and    injecting atomic hydrogen at a pressure of between about 10 −3  and 10 −4  Torr into the vacuum chamber.    
     
     
         2 . The method of  claim 1 , wherein the contaminated surface is the surface of a multilayer optic.  
     
     
         3 . The method of  claim 2 , w herein the multilayer optic is a Si-capped Mo/Si multilayer optic or a Ru—B 4 C-capped Mo/Si multilayer optic.  
     
     
         4 . A system for removing contaminants from a surface, comprising: 
 a housing defining a vacuum chamber in which a surface to be cleaned is located; and    a source of atomic hydrogen capable of injecting atomic hydrogen into the vacuum chamber, w herein pressure of atomic hydrogen within the vacuum chamber is between 10 −3  to 10 −4  Torr, and wherein the surface is at a temperature of less than about 50° C. throughout the cleaning process.    
     
     
         5 . The system of  claim 4 , w herein the surface is the surface of a multilayer optic.  
     
     
         6 . The system of  claim 5 , wherein the multilayer optic is a Si-capped Mo/Si multilayer optic or a Ru—B 4 C-capped Mo/Si multilayer optic.