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, the method including:
 directing and focussing focusing 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 said layer and 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 at least in part 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 surface of said at least one optical element nearest to said layer, wherein a passage is formed in said wall as an opening from the recess, wherein said wall has a width-wise axis that extends through the body of the wall, the width-wise axis essentially extending perpendicular to an optical axis, through the interspace, of the radiation beam, wherein said wall has a major exterior surface contacting said liquid, the major exterior surface being essentially perpendicular to the optical axis, extending at least partly underneath said at least one optical element, being a bottom-most surface of the wall and spanning a width that is larger than a height of the wall, and wherein said radiation beam passing passes through said passage while at least a portion of the liquid is flowing out of said passage onto said layer. 
 
     
     
       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 at a value selected from within the range 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 0.5*β*H*(W+α*H)*V, where • α is a constant between 1 and 10 and • β is a constant between 1 and 3. 
     
     
       8. A device for directing radiation to a layer, the device including:
 at least one optical element for focussing a radiation originating beam from said a 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,; and 
 characterized in that said device further comprises a recess having an internal surface bounding at least said a portion of said interspace through which said radiation irradiates said spot on said layer through said liquid, said outflow opening being formed in said recess, wherein said recess is being bounded at least in part 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, a passage for liquid flow formed in said wall, wherein said wall has a width-wise axis that extends through the body of the wall, the width-wise axis essentially extending perpendicular to an optical axis, through the interspace, of the radiation beam, wherein said wall has a major exterior surface arranged to contact said liquid, the major exterior surface being essentially perpendicular to the optical axis, extending at least partly underneath said at least one optical element, being a bottom-most surface of the wall and spanning a width that is larger than a height of the wall, and wherein said outflow opening is formed in said recess above said passage and said passage forming said outflow opening is a further opening in the recess and is arranged to have the radiation beam pass therethrough onto said spot. 
 
     
     
       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 at a value selected from within the range 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. The method as claimed in claim 1, wherein said major surface of the wall is upward facing. 
     
     
       15. A device manufacturing method comprising:
 forming a beam of radiation with an image of a mask or reticle; and   irradiating a layer with the image using the method as claimed in claim 1.   
     
     
       16. The device as claimed in claim 8, wherein said major surface of the wall is upward facing. 
     
     
       17. A lithography apparatus comprising:
 a wafer support table configured to support a wafer to be irradiated;   a scanner configured to have a reticle or mask;   a drive, coupled to the wafer support table, configured to move the support table in X and Y directions;   a control unit configured to control the drive and the scanner; and   a device as claimed in claim 8.   
     
     
       18. A method comprising:
 directing and focusing a radiation beam to a spot on a 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 said layer and 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,   wherein 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 throuqh said liquid in said recess when irradiating said spot, and wherein the boundary of said recess is formed at least in part by a wall between said layer and said surface of said at least one optical element nearest to said layer, wherein a passage for liquid flow is formed in said wall as an opening from the recess, wherein said wall has a width-wise axis that extends through the body of the wall, the width-wise axis essentially extending perpendicular to an optical axis, through the interspace, of the radiation beam, wherein said wall has a major exterior surface contacting said liquid, the maior exterior surface being essentially perpendicular to the optical axis, extending at least partly underneath said at least one optical element, being a bottom-most surface of the wall and spanning a width that is larger than a height of the wall, and wherein said radiation beam passes through said passage while at least a portion of the liquid is flowing out of said passage onto said layer.   
     
     
       19. A device manufacturing method comprising:
 forming a beam of radiation with an image of a mask or reticle; and   irradiating a layer with the image using the method as claimed in claim 18.   
     
     
       20. A device comprising:
 at least one optical element configured to focus a radiation beam from a radiation source to a spot on a layer;   a displacement structure configured to cause relative movement of the layer relative to said at least one optical element so that different portions of the layer are irradiated;   an outflow opening configured to supply liquid to fill an interspace between said layer and a surface of said at least one optical element nearest to said spot; and   a recess having an internal surface bounding at least a portion of said interspace through which said radiation irradiates said spot on said layer through said liquid, said recess being bounded at least in part by a wall between said layer and said surface of said at least one optical element nearest to said layer, a passage being formed in said wall, wherein said wall has a width-wise axis that extends through the body of the wall, the width-wise axis essentially extending perpendicular to an optical axis, through the interspace, of the radiation beam, wherein said wall has a major exterior surface arranged to contact said liquid, the major exterior surface being essentially perpendicular to the optical axis, extending at least partly underneath said at least one optical element, being a bottom-most surface of the wall and spanning a width that is larger than a height of the wall, and wherein said outflow opening is formed in said recess above said passage and said passage is a further opening in the recess and is arranged to have the radiation beam pass therethrough onto said spot.   
     
     
       21. A lithography apparatus comprising:
 a wafer support table configured to support a wafer to be irradiated;   a scanner configured to have a reticle or mask;   a drive, coupled to the wafer support table, configured to move the support table in X and Y directions;   a control unit configured to control the drive and the scanner; and   a device as claimed in claim 20.