Lithographic apparatus, alignment apparatus, device manufacturing method, and a method of converting an apparatus

Abstract

A detector detects liquid in the path of a projection beam or alignment beam. A controller then determines which one or more of a plurality of compensating optical elements may be provided in the optical path of the projection beam or alignment beam in order to focus the projection beam or alignment beam on the surface of the substrate. The appropriate optical element may be placed in the path of the projection beam or alignment beam directly as a final element of the projection system or alignment system respectively.

1 .- 88 . (canceled) 
   
   
       89 . A lithographic apparatus comprising:
 a support structure configured to hold a patterning device, the patterning device configured to provide a beam of radiation having a pattern in its cross-section;   a substrate table configured to hold a substrate;   a projection lens system configured to project the patterned beam onto a target portion of the substrate;   a plurality of optical elements removably positionable in the path of the beam to adjust the focal plane of the beam; and   a plurality of docking stations at different positions along the path of the beam configured to hold the plurality of optical elements depending on the presence or absence of liquid between the projection lens system and the substrate.   
   
   
       90 . An apparatus according to  claim 89 , wherein each docking station is a predetermined distance from a final non-parallel plate element of the projection lens system. 
   
   
       91 . An apparatus according to  claim 90 , wherein at least one docking station is arranged such that the focal point of the beam is on the substrate, or the substrate table, or both the substrate and the substrate table, when no liquid is present in the path of the beam. 
   
   
       92 . An apparatus according to  claim 90 , wherein at least one docking station is arranged such that the focal point of the beam is on the substrate, or the substrate table, or both the substrate and the substrate table, when a liquid is present in the optical path of the beam. 
   
   
       93 . An apparatus according to  claim 89 , further comprising a controller configured to control which one or more of the plurality of optical elements is placed in the path of the beam dependent on a quantity of liquid between the projection lens system and the substrate table. 
   
   
       94 . An apparatus according to  claim 89 , further comprising a liquid supply system configured to at least partly fill a space between the projection lens system and the substrate table, with a liquid. 
   
   
       95 . An alignment apparatus comprising:
 a substrate table configured to hold a substrate, the substrate having a substrate mark;   an alignment lens system configured to detect alignment between a reference mark and the substrate mark using an alignment beam of radiation;   a plurality of optical elements removably positionable in the path of the alignment beam configured to adjust the focal plane of the alignment lens system when detecting alignment; and   a plurality of docking stations at different positions along the path of the alignment beam configured to hold the plurality of optical elements depending on the presence or absence of liquid between the alignment lens system and the substrate.   
   
   
       96 . An apparatus according to  claim 95 , wherein each docking station is a predetermined distance from a final non-parallel plate element of the alignment lens system. 
   
   
       97 . An apparatus according to  claim 96 , wherein at least one docking station is arranged such that the focal point of the alignment beam is on the substrate, or the substrate table, or both the substrate and the substrate table, when no liquid is present in the path of the alignment beam. 
   
   
       98 . An apparatus according to  claim 96 , wherein at least one docking station is arranged such that the focal point of the alignment beam is on the substrate, or the substrate table, or both the substrate and the substrate table, when a liquid is present in the optical path of the alignment beam. 
   
   
       99 . An apparatus according to  claim 95 , further comprising a controller configured to control which one or more of the plurality of optical elements is placed in the path of the alignment beam dependent on a quantity of liquid between the alignment lens system and the substrate table. 
   
   
       100 . An apparatus according to  claim 95 , further comprising a liquid supply system configured to at least partly fill a space between the alignment lens system and the substrate table, with a liquid. 
   
   
       101 . A lithographic projection apparatus comprising a support structure configured to hold a patterning device that serves to provide a beam of radiation according to a desired pattern, a projection system configured to project the patterned beam onto a target portion of the substrate, and an alignment apparatus according to  claim 95 . 
   
   
       102 . An apparatus according to  claim 101 , wherein the alignment beam traverses at least part of the projection system. 
   
   
       103 . An alignment apparatus comprising:
 a substrate table configured to hold a substrate, the substrate having a substrate mark;   an alignment lens system configured to detect alignment between a reference mark and the substrate mark using an alignment beam of radiation;   a plurality of optical elements removably positionable in the path of the alignment beam configured to adjust the focal plane of the alignment lens system when detecting alignment;   a detector configured to detect the presence or absence of liquid between the alignment lens system and the substrate table; and   a controller configured to control which one or more of the plurality of optical elements is placed in the path of the alignment beam on the basis of results from the detector.   
   
   
       104 . An apparatus according to  claim 103 , further comprising a liquid supply system configured to at least partly fill a space between the alignment lens system and the substrate table, with a liquid. 
   
   
       105 . A lithographic projection apparatus comprising a support structure configured to hold a patterning device that serves to provide a beam of radiation according to a desired pattern, a projection system configured to project the patterned beam onto a target portion of the substrate, and an alignment apparatus according to  claim 103 . 
   
   
       106 . An apparatus according to  claim 105 , wherein the alignment beam traverses at least part of the projection system. 
   
   
       107 . A lithographic projection apparatus comprising:
 a support structure configured to hold a patterning device, the patterning device configured to provide a beam of radiation having a pattern in its cross-section;   a substrate table configured to hold a substrate;   a projection lens system configured to project the patterned beam onto a target portion of the substrate;   a liquid supply system configured to at least partly fill a space between the projection lens system and the substrate table, with a liquid; and   a detector configured to detect the presence or absence of liquid between the projection lens system and the substrate table.   
   
   
       108 . An apparatus according to  claim 107 , further comprising a controller configured to control an optical element in the path of the beam or control insertion of an optical element into the path of the beam, dependent on the results from the detector.