Radiation system and lithographic apparatus

Abstract

A radiation system for generating a beam of radiation that defines an optical axis is provided. The radiation system includes a plasma produced discharge source for generating EUV radiation. The discharge source includes a pair of electrodes constructed and arranged to be provided with a voltage difference, and a system for producing a plasma between the pair of electrodes so as to provide a discharge in the plasma between the electrodes. The radiation system also includes a debris catching shield for catching debris from the electrodes. The debris catching shield is constructed and arranged to shield the electrodes from a line of sight provided in a predetermined spherical angle relative the optical axis, and to provide an aperture to a central area between the electrodes in the line of sight.

1 . A radiation system for generating a beam of radiation in a radiation space, the radiation system comprising:
 a plasma produced discharge source constructed and arranged to generate extreme ultraviolet radiation, the discharge source comprising a pair of electrodes constructed and arranged to be provided with a voltage difference, and a system constructed and arranged to produce a discharge between said pair of electrodes so as to provide a pinch plasma between said electrodes; and   a debris catching shield constructed and arranged to catch debris from said electrodes, to shield said electrodes from a line of sight provided in the radiation space, and to provide an aperture to a central area between said electrodes in said line of sight.   
   
   
       2 . (canceled) 
   
   
       3 . A radiation system according to  claim 1 , wherein the debris catching shield comprises at least one fluid jet. 
   
   
       4 . A radiation system according to  claim 3 , wherein the fluid jet comprises molten tin or a tin compound. 
   
   
       5 . (canceled) 
   
   
       6 . A radiation system according to  claim 1 , wherein the debris catching shield is provided by a pair of fluid jets, arranged oppositely and generally parallel to a longitudinal axis of the electrodes. 
   
   
       7 . A radiation system according to  claim 3 , wherein the debris catching shield comprises a plurality of fluid jets, arranged in radial direction relative from the central area. 
   
   
       8 . (canceled) 
   
   
       9 . (canceled) 
   
   
       10 . (canceled) 
   
   
       11 . (canceled) 
   
   
       12 . A radiation system according to  claim 1 , wherein the debris catching shield comprises a static configuration of generally radially oriented platelets, relative to said central area, wherein the platelets are oriented to shield the electrodes from a line of sight provided between said platelets. 
   
   
       13 . A radiation system according to  claim 12 , wherein a distance between the platelets is increased relative to distances away from the optical axis. 
   
   
       14 . (canceled) 
   
   
       15 . A radiation system according to  claim 12 , further comprising an electromagnetic deflecting field unit disposed for applying an electromagnetic deflecting field between the electrodes and the shield. 
   
   
       16 . A radiation system according to  claim 15 , wherein said electromagnetic deflecting field unit provides a static magnetic field. 
   
   
       17 . (canceled) 
   
   
       18 . (canceled) 
   
   
       19 . A radiation system according to  claim 12 , further comprising a hydrogen radical supply system for guiding hydrogen radicals through said platelets. 
   
   
       20 . (canceled) 
   
   
       21 . (canceled) 
   
   
       22 . (canceled) 
   
   
       23 . A radiation system according to  claim 12  wherein at least some of the platelets are provided by a fluid jet. 
   
   
       24 . A radiation system according to  claim 23 , wherein the fluid jet comprises molten tin or a tin compound. 
   
   
       25 . (canceled) 
   
   
       26 . A radiation system according to  claim 1 , further comprising a heating system that can be selectively heated for elevating a temperature of said debris catching shield to a temperature for evaporating said debris from said debris catching shield; and a gas supply system for providing a gas flow to evacuate said evaporated debris from said debris catching shield. 
   
   
       27 . (canceled) 
   
   
       28 . (canceled) 
   
   
       29 . (canceled) 
   
   
       30 . A radiation system according to  claim 12 , wherein the platelets are provided as a material of porous characteristics for removing said debris from said platelets through capillary action. 
   
   
       31 . A radiation system according to  claim 12 , further comprising an excitator for removing said debris from said platelets through mechanical excitation of said platelets. 
   
   
       32 . (canceled) 
   
   
       33 . (canceled) 
   
   
       34 . (canceled) 
   
   
       35 . A radiation system according to  claim 1 , wherein the system that is constructed and arranged to produce a discharge between said pair of electrodes comprises a laser. 
   
   
       36 . A radiation system according to  claim 1 , wherein the electrodes define a discharge axis interconnecting said electrodes and wherein the radiation space is substantially bounded between two mutually reversely oriented cones relative to the discharge axis, the cones having their apex substantially in the central area between the electrodes. 
   
   
       37 . (canceled) 
   
   
       38 . A radiation system according to  claim 12 , wherein platelets have concentric conical surfaces and/or comprise at least one planar section. 
   
   
       39 . (canceled) 
   
   
       40 . (canceled) 
   
   
       41 . A radiation system according to  claim 12 , comprising a wiping module provided with a multiple number of wiping elements movable along respective platelet surfaces. 
   
   
       42 . (canceled) 
   
   
       43 . (canceled) 
   
   
       44 . (canceled) 
   
   
       45 . (canceled) 
   
   
       46 . (canceled) 
   
   
       47 . A lithographic apparatus comprising:
 a radiation system constructed and arranged to generate a beam of radiation defining in a radiation space, the radiation system comprising:
 a plasma produced discharge source constructed and arranged to generate extreme ultraviolet radiation, the discharge source comprising a pair of electrodes constructed and arranged to be provided with a voltage difference, and a system constructed and arranged to produce a discharge between said pair of electrodes so as to provide a pinch plasma between said electrodes; and 
 a debris catching shield constructed and arranged to catch debris from said electrodes, to shield said electrodes from a line of sight provided in the radiation space, and to provide an aperture to a central area between said electrodes in said line of sight; 
 a patterning device constructed and arranged to pattern the beam of radiation; and 
 a projection system constructed and arranged to project the patterned beam of radiation onto a substrate.