Cleaning device, a lithographic apparatus and a lithographic apparatus cleaning method

Abstract

A cleaning tool to clean a surface of a liquid confinement system of an immersion lithographic apparatus is disclosed, the liquid confinement system having an aperture to allow passage of a beam of radiation therethrough of an immersion lithographic apparatus. The cleaning tool includes a sonic transducer, a reservoir configured to hold liquid between the sonic transducer and the surface to be cleaned, and a barrier positioned in the reservoir under the aperture to form, in use, a shield to sonic waves.

1 - 30 . (canceled) 
     
     
         31 . A lithographic projection apparatus comprising:
 a projection system configured to project a beam of radiation;   a liquid confinement system configured to confine liquid in an aperture, the aperture arranged to allow passage of the beam therethrough and the aperture being open to a final element of the projection system;   a cleaning tool configured to clean a bottom surface of the liquid confinement system, the cleaning tool comprising a sonic transducer and having a cleaning area smaller in size than the entire bottom surface of the liquid confinement system; and   a liquid supply device configured to provide liquid between the sonic transducer and the bottom surface of the liquid confinement system.   
     
     
         32 . The apparatus of  claim 31 , wherein the cleaning tool is configured to clean a plurality of openings of the bottom surface. 
     
     
         33 . The apparatus of  claim 31 , wherein the cleaning tool is configured to clean an area of the bottom surface outward of the rim of the aperture. 
     
     
         34 . The apparatus of  claim 31 , wherein the liquid supply device comprises an opening, in the bottom surface, to provide the liquid between the sonic transducer and the bottom surface. 
     
     
         35 . The apparatus of  claim 31 , further comprising an opening in the bottom surface to remove liquid from between the sonic transducer and the liquid confinement structure. 
     
     
         36 . The apparatus of  claim 31 , wherein the cleaning tool comprises an outer rim, immediately adjacent the bottom surface, extending within the outer boundary of the bottom surface. 
     
     
         37 . The apparatus of  claim 36 , wherein the cleaning tool comprises an inner rim, immediately adjacent the bottom surface, within the outer rim and being at or outside of the boundary of the aperture. 
     
     
         38 . A method of cleaning a liquid confinement system, the method comprising:
 providing liquid between a bottom surface of the liquid confinement system and a sonic wave source;   generating sonic waves and directing them in the liquid towards the bottom surface; and   using a barrier to prevent the sonic waves from reaching an optical element positioned in an aperture in the surface of the liquid confinement system.   
     
     
         39 . The method of  claim 38 , wherein the barrier prevents the sonic waves from reaching the optical element by maintaining a gas gap in the aperture below the optical element and/or by blocking the sonic waves by its physical presence. 
     
     
         40 . The method of  claim 38 , further comprising releasably sealing between the aperture and the barrier. 
     
     
         41 . The method of  claim 38 , comprising moving the barrier under the liquid confinement system. 
     
     
         42 . The method of  claim 38 , comprising removing liquid provided between the bottom surface of the liquid confinement system and the sonic wave source using a liquid outlet that is a physically separate structure from the liquid confinement system. 
     
     
         43 . A lithographic projection apparatus comprising:
 a projection system configured to project a beam of radiation;   a liquid confinement system configured to confine liquid in an aperture, the aperture arranged to allow passage of the beam therethrough and the aperture being open to a final element of the projection system; and   a cleaning tool configured to cleaning a bottom surface of the liquid confinement system, the cleaning tool comprising a sonic transducer, a liquid supply device configured to provide liquid between the sonic transducer and the bottom surface of the liquid confinement system, and a barrier configured to form a shield to prevent sonic waves from reaching the final element.   
     
     
         44 . The apparatus of  claim 43 , wherein the barrier, in use, forms a shield by its physical presence and/or by maintaining a gas gap in the aperture between the barrier and the final element. 
     
     
         45 . The apparatus of  claim 43 , further comprising a releasable seal configured to seal between the aperture and the barrier. 
     
     
         46 . The apparatus of  claim 45 , wherein the barrier, in cross-section, is funnel shaped. 
     
     
         47 . The apparatus of  claim 43 , wherein the barrier comprises an outlet in its upper surface. 
     
     
         48 . The apparatus of  claim 43 , wherein the barrier has an outer rim and any liquid which flows over the rim flows into the outlet under gravity. 
     
     
         49 . The apparatus of  claim 43 , wherein a flow path for liquid between the barrier and the liquid confinement system from the reservoir into the aperture is not straight. 
     
     
         50 . The apparatus of  claim 43 , wherein, in use, the barrier is positioned under the liquid supply device and the barrier comprises a liquid outlet configured to remove liquid provided by the liquid supply device during projection of a patterned beam onto a substrate, the liquid outlet being a physically separate structure from the liquid confinement system.