Method and device for irradiating spots on a layer

Abstract

For irradiating a layer a radiation beam is directed and focussed to a spot on the layer, relative movement of the layer relative to the lens is caused so that, successively, different portions of the layer are irradiated and an interspace between a surface of the lens nearest to the layer is maintained. Furthermore, at least a portion of the interspace through which the radiation irradiates the spot on the layer is maintained filled with a liquid, the liquid being supplied via a supply conduit. At least a portion of the liquid fills up a recess through which the radiation irradiates the spot.

The invention claimed is: 
     
       1. A method of irradiating a layer including:
 directing and focussing a radiation beam to a spot on said layer by means of at least one optical element;   causing relative movement of the layer relative to said at least one optical element so that, successively, different portions of the layer are irradiated and an interspace between a surface of said at least one optical element nearest to said layer is maintained; and   maintaining said interspace through which said radiation irradiates said spot on said layer filled with a liquid, the liquid being supplied via a supply conduit;   characterized in that at least a portion of said interspace is bounded by a recess which is filled by at least a portion of said liquid, said radiation beam passing through said liquid in said recess when irradiating said spot, wherein said recess is bounded by a passage in a wall between said layer and a surface of said at least one optical element nearest to said layer and by said at least one optical element nearest to said layer, said radiation beam passing through said passage.   
     
     
       2. The method as claimed in  claim 1 , wherein the recess has a rim portion positioned between said surface of said at least one optical element nearest to said layer and said layer, closest to said layer and extending around said radiation beam irradiating said spot. 
     
     
       3. The method as claimed in  claim 1 , wherein a liquid outflow from said recess via said passage is maintained. 
     
     
       4. A The method as claimed in  claim 1 , wherein a smallest thickness of said interspace is maintained of 3-1500 μm. 
     
     
       5. A The method as claimed in  claim 1 , wherein said recess includes a concave portion of said surface of said at least one optical element nearest to said layer. 
     
     
       6. A The method as claimed in  claim 1 , wherein the liquid flows out from at least one outflow opening in said recess in the form of at least one canal open towards said layer, said canal distributing supplied liquid longitudinally along said canal and dispensing distributed liquid towards said layer. 
     
     
       7. A method of irradiating a layer including:
 directing and focusing a radiation beam to spot on said layer by means of at least one optical element;   causing relative movement of the layer relative to said at least one optical element so that, successively, different portions of the layer are irradiated and an interspace between a surface of said at least one optical element nearest to said layer is maintained; and   maintaining at least a portion of said interspace through which said radiation irradiates said spot on said layer filled with a liquid, the liquid being supplied via a supply conduit;   characterized in that at least a portion of said liquid fills up a recess through which said radiation irradiates said spot,   
       wherein said interspace between said layer and said surface of said at least one optical element nearest to said layer has a thickness H, the layer and the at least one optical element are moved relative to each other at a velocity V, the liquid is supplied via an outflow opening having a width W measured in a plane parallel to said layer and at a flow rate equal to 0.5*⋅*H*(W+⋅*H)*V, where ⋅ is a constant between 1 and 10 and ⋅ is a constant between 1 and 3. 
     
     
       8. A device for directing radiation to a layer including:
 at least one optical element for focussing radiation originating from said radiation source to a spot on said layer;   a displacement structure for causing relative movement of the layer relative to said at least one optical element so that, successively, different portions of the layer are irradiated and an interspace between said layer and a surface of said at least one optical element nearest to said spot is maintained; and   an outflow opening for supplying liquid to fill said interspace, in operation, said radiation irradiates said spot on said layer through said liquid,   characterized in that said device further comprises a recess having an internal surface bounding at least said portion of said interspace through which said radiation irradiates said spot, said outflow opening being formed in said recess, wherein said recess is bounded by a passage in a wall between said spot and a surface of said at least one optical element nearest to said spot and by said surface of said at least one optical element nearest to said spot, said passage forming said outflow opening.   
     
     
       9. The device as claimed in  claim 8 , wherein said recess has a rim portion closest to said layer extending around said portion of said interspace through which, in operation, said radiation irradiates said spot. 
     
     
       10. The device as claimed in  claim 8 , wherein said device further comprises a liquid supply structure communicating with said recess for maintaining a liquid outflow via said passage. 
     
     
       11. The device as claimed in  claim 8 , wherein said device is arranged for maintaining a smallest thickness of said interspace of 3-1500 μm. 
     
     
       12. The device as claimed in  claim 8 , wherein said recess includes a concave portion of said surface of said at least one optical element nearest to said spot. 
     
     
       13. The device claimed in  claim 8 , wherein the at least one outflow opening is formed by at least one canal open towards said layer, for distributing supplied liquid longitudinally along said canal and dispensing distributed liquid towards said layer. 
     
     
       14. A structure for a lithography apparatus comprising a movable wafer support table configured to support a wafer, and an optical element, nearest to the wafer support table, configured to pass a radiation beam from a reticle or mask to the wafer, the structure configured for being located adjacent the optical element, configured to receive a liquid and configured to maintain an interspace between a bottom surface of the optical element and the wafer support table and through which the radiation beam irradiates the wafer, filled with the liquid, the structure comprising:
 an internal surface to bound at least a portion of the interspace between the bottom surface of the optical element and the wafer support table,   a wall configured to be between the wafer and the surface of the optical element, wherein the interspace is bounded at least in part by the wall and by the surface of the optical element, wherein the wall is arranged to extend essentially perpendicularly to an optical axis, through the interspace, of the radiation beam and has its width in a horizontal direction larger than its height in a vertical direction,   a passage formed in the wall, the passage arranged to allow the radiation beam and liquid to pass therethrough out onto the wafer, and   a port configured to fill the interspace with the liquid, wherein the port is located inside the structure.   
     
     
       15. The structure of claim 14, wherein the wall is configured to extend at least partly underneath the surface of the optical element. 
     
     
       16. The structure of claim 14, further comprising a channel configured to be located at least partly below the surface of the optical element, the channel configured to direct a flow of the liquid in a direction essentially perpendicular to the optical axis. 
     
     
       17. The structure of claim 16, wherein parts of the channel are arranged to be located on opposite sides of the optical axis. 
     
     
       18. The structure of claim 14, wherein a cross-sectional dimension of the passage is arranged to be smaller than a cross-sectional dimension of the optical element. 
     
     
       19. The structure of claim 14, wherein the wall is arranged to intersect at an angle a further wall at a location below the surface of the optical element. 
     
     
       20. The structure of claim 14, wherein the structure has its width in a horizontal direction larger than its height in a vertical direction. 
     
     
       21. A structure for a lithography apparatus comprising a movable wafer support table configured to support a wafer, and an optical element, nearest to the wafer support table, configured to pass a radiation beam from a reticle or mask to the wafer, the structure configured for being located adjacent the optical element, configured to receive a liquid and configured to maintain an interspace between a bottom surface of the optical element and the wafer support table and through which the radiation beam irradiates the wafer, filled with the liquid, the structure comprising:
 an internal surface bounding at least a portion of the interspace between the bottom surface of the optical element and the wafer support table,   a wall between the wafer and the surface of the optical element, wherein the interspace is bounded at least in part by the wall and by the surface of the optical element, wherein the wall comprises an essentially plane parallel plate arranged to extend essentially perpendicularly to an optical axis, through the interspace, of the radiation beam,   a passage formed in the wall, the passage arranged to allow the radiation beam and liquid to pass therethrough out onto the wafer, and   a port configured to fill the interspace with the liquid, wherein the port is located inside the structure.   
     
     
       22. The structure of claim 21, wherein the wall is configured to extend at least partly underneath the surface of the optical element. 
     
     
       23. The structure of claim 21, further comprising a channel configured to be located at least partly below the surface of the optical element, the channel configured to direct a flow of the liquid in a direction essentially perpendicular to the optical axis. 
     
     
       24. The structure of claim 21, wherein a cross-sectional dimension of the passage is arranged to be smaller than a cross-sectional dimension of the optical element. 
     
     
       25. The structure of claim 21, wherein the wall has its width in a horizontal direction larger than its height in a vertical direction. 
     
     
       26. The structure of claim 21, wherein the wall is arranged to intersect at an angle a further wall at a location below the surface of the optical element. 
     
     
       27. The structure of claim 21, wherein the structure has its width in a horizontal direction larger than its height in a vertical direction. 
     
     
       28. A structure for a lithography apparatus comprising a movable wafer support table configured to support a wafer, and an optical element, nearest to the wafer support table, configured to pass a radiation beam from a reticle or mask to the wafer, the structure configured for being located adjacent the optical element, configured to receive a liquid and configured to maintain an interspace between a surface of the optical element and the wafer support table and through which the radiation beam irradiates the wafer, filled with the liquid, the structure comprising:
 an internal surface to bound at least a portion of the interspace between the surface of the optical element and the wafer support table,   a wall configured to be between the wafer and the surface of the optical element, wherein the interspace is bounded at least in part by the wall and by the surface of the optical element, wherein the wall is arranged to have a surface nearest the wafer when supported by the wafer support table that is essentially perpendicular to an optical axis, through the interspace, of the radiation beam,   a passage formed in the wall, the passage arranged to allow the radiation beam and liquid to pass therethrough out onto the wafer, and   a port configured to fill the interspace with the liquid, wherein the port is located inside the structure.   
     
     
       29. The structure of claim 28, wherein the wall is configured to extend at least partly underneath the surface of the optical element. 
     
     
       30. The structure of claim 28, further comprising a channel configured to be located at least partly below the surface of the optical element, the channel configured to direct a flow of the liquid in a direction essentially perpendicular to the optical axis. 
     
     
       31. The structure of claim 28, wherein a cross-sectional dimension of the passage is arranged to be smaller than a cross-sectional dimension of the optical element. 
     
     
       32. The structure of claim 28, wherein the wall has its width in a horizontal direction larger than its height in a vertical direction. 
     
     
       33. The structure of claim 28, wherein the structure has its width in a horizontal direction larger than its height in a vertical direction.