Lithographic apparatus and device manufacturing method

Abstract

An attenuation adjustment device is disclosed that includes a plurality of members configured to cast penumbras in a radiation beam illuminating a patterning device in a lithography apparatus. Furthermore, an attenuation control device may be provided to adjust the members in such a manner as to control attenuation of a radiation beam projected onto a target portion of a substrate across the cross-section of the radiation beam.

1 . A lithographic apparatus, comprising: 
 an illumination system configured to condition a radiation beam;    a support constructed to hold a patterning device, the patterning device being constructed to impart a cross-sectional pattern to the radiation beam to form a patterned radiation beam;    a substrate table constructed to hold a substrate;    a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and    an attenuation adjustment device comprising a plurality of members configured to cast penumbras in the radiation beam illuminating the patterning device, each member configured to increase or decrease its penumbra by displacement of a portion of the member in a direction substantially perpendicular to an axis of the member.    
   
   
       2 . The apparatus of  claim 1 , wherein each member comprises a central structure along the axis, a first structure movable along the central structure, and a flexible material attached to the first structure, wherein the portion of the member comprises the flexible material and movement of the first structure causes displacement of the flexible material in the direction.  
   
   
       3 . The apparatus of  claim 2 , wherein the first structure is attached to one end of the flexible material and another end of the flexible material is fixed relative the central structure at a position displaced from the first structure, the flexible material extending between the first structure and the position along at least a portion of the central structure.  
   
   
       4 . The apparatus of  claim 2 , wherein the first structure is attached to one end of the flexible material and further comprising a second structure movable along the central member to which another end of the flexible material is attached.  
   
   
       5 . The apparatus of  claim 4 , wherein both the first structure and the second structure are movable in a same direction to displace the portion of the member in a direction substantially parallel to the axis.  
   
   
       6 . The apparatus of  claim 4 , wherein the first structure and the second structure are movable towards each other to cause displacement of the flexible material in the direction.  
   
   
       7 . The apparatus of  claim 1 , wherein at least one of the plurality of members is further configured displace the portion of the member in a direction substantially parallel to the axis of the member.  
   
   
       8 . The apparatus of  claim 1 , further comprising a scanning system configured to provide relative movement between the radiation beam and the target portion of the substrate in a scanning direction, the members being distributed along a path transverse to the scanning direction.  
   
   
       9 . The apparatus of  claim 8 , wherein the scanning system comprises a slit extending across the path through which the radiation beam is to be projected onto the target portion of the substrate, and further comprising an attenuation control device arranged to adjust the members by different amounts in such a manner that an intensity of the radiation beam is substantially constant over a length of the slit.  
   
   
       10 . The apparatus of  claim 8 , further comprising an attenuation control device arranged to adjust the members in such a manner as to permit an intensity of the radiation beam projected onto the target portion of the substrate to be varied in a direction transverse to the scanning direction during the scanning.  
   
   
       11 . The apparatus of  claim 8 , further comprising an attenuation control device arranged to adjust the members in such a manner as to permit an intensity of the radiation beam projected onto the target portion of the substrate to be varied both in the scanning direction and in a direction transverse to the scanning direction.  
   
   
       12 . The apparatus of  claim 1 , further comprising a position detector configured to provide an output indicative of a position of each member in dependence on detection of a beam of detecting radiation reaching the position detector after attenuation or redirection by the member.  
   
   
       13 . The apparatus of  claim 12 , further comprising an attenuation control device configured to use feedback control to supply a control signal to at least one of the members to drive that member to an adjustment position according to the output indicative of the position of that member received from the position detector.  
   
   
       14 . The apparatus of  claim 12 , further comprising a detection vane portion of each member spaced from the portion of the member, the detection vane portion of each member configured to attenuate the beam of detecting radiation detected by the position detector.  
   
   
       15 . A lithographic apparatus, comprising: 
 an illumination system configured to condition a radiation beam;    a support constructed to hold a patterning device, the patterning device being constructed to impart a cross-sectional pattern to the radiation beam to form a patterned radiation beam;    a substrate table constructed to hold a substrate and move the substrate in a scanning direction;    a projection system configured to project the patterned radiation beam onto a target portion of the substrate;    an attenuation adjustment device comprising a plurality of members configured to cast penumbras in the radiation beam illuminating the patterning device; and    an attenuation control device configured to adjust the members so as to control attenuation of the radiation beam, during scanning projection of the patterned radiation beam, in the scanning direction across the radiation beam and in a second direction across the radiation beam substantially perpendicular to the scanning direction, the attenuation control device comprising a respective position detector configured to provide an output indicative of position of each member in dependence on detection of a beam of detecting radiation reaching the position detector after attenuation by the member.    
   
   
       16 . The apparatus of  claim 15 , wherein each member is configured to increase or decrease its penumbra by displacement of a portion of the member in a direction substantially perpendicular to an axis of the member.  
   
   
       17 . The apparatus of  claim 16 , wherein at least one of the plurality of members is further configured displace the portion of the member in a direction substantially parallel to the axis of the member.  
   
   
       18 . The apparatus of  claim 15 , further comprising a slit extending across the path through which the radiation beam is to be projected onto the target portion of the substrate, and wherein the attenuation control device is arranged to adjust the members by different amounts in such a manner that an intensity of the radiation beam is substantially constant over a length of the slit.  
   
   
       19 . A device manufacturing method, comprising: 
 casting penumbras on a patterning device using a plurality of members in the path of the radiation beam, each member configured to increase or decrease its penumbra by displacement of a portion of the member in a direction substantially perpendicular to an axis of the member;    imparting a cross-sectional pattern to the radiation beam using the patterning device to form a patterned radiation beam; and    projecting the patterned radiation beam onto a target portion of a substrate.    
   
   
       20 . The method of  claim 19 , wherein at least one of the plurality of members is further configured displace the portion of the member in a direction substantially parallel to the axis of the member.