Radiation system and lithographic apparatus

Abstract

The invention relates to a radiation system for generating a beam of radiation. The radiation system includes an extreme ultraviolet source for generating extreme ultraviolet radiation, a contamination barrier for trapping contamination from the radiation source, and a temperature sensor for sensing a temperature of the contamination barrier.

1 . A radiation system for generating a beam of radiation comprising: 
 an extreme ultraviolet radiation source for generating extreme ultraviolet radiation;    a contamination barrier for trapping contamination from said radiation source; and    a temperature sensor for measuring a temperature of said contamination barrier.    
   
   
       2 . A radiation system according to  claim 1 , wherein the temperature sensor comprises a probe facing the contamination barrier and is arranged to be heated contactlessly by said contamination barrier.  
   
   
       3 . A radiation system according to  claim 2 , wherein said probe is formed to substantially conform to a geometry of the contamination barrier.  
   
   
       4 . A radiation system according to  claim 2 , wherein said probe is formed to substantially conform to a blackbody geometry.  
   
   
       5 . A radiation system according to  claim 4 , wherein said blackbody geometry is provided by a concave shape for providing a high apparent emissivity.  
   
   
       6 . A radiation system according to  claim 2 , wherein said probe is thermally isolated on sides not facing the contamination barrier.  
   
   
       7 . A radiation system according to  claim 2 , wherein said probe comprises a metal plate.  
   
   
       8 . A radiation system according to  claim 7 , wherein said metal plate is tin covered.  
   
   
       9 . A radiation system according to  claim 2 , wherein a thermocouple sensor is coupled to said probe and is arranged to be heated only by direct thermal contact with the probe.  
   
   
       10 . A radiation system according to  claim 1 , further comprising a heater at least partly enclosing said contamination barrier.  
   
   
       11 . A radiation system according to  claim 1 , wherein said temperature sensor is coupled directly to the contamination barrier.  
   
   
       12 . A radiation system according to  claim 11 , wherein said contamination barrier is of a rotating type, and wherein said temperature sensor is coupled to a rotation axis of the contamination barrier.  
   
   
       13 . A radiation system according to  claim 1 , wherein said contamination barrier is of a rotating foil trap type.  
   
   
       14 . A radiation system according to  claim 1 , wherein said extreme ultraviolet radiation source is a laser induced plasma source.  
   
   
       15 . A radiation system according to  claim 14 , wherein said plasma source comprises Tin, Lithium, or Xenon.  
   
   
       16 . A radiation system for generating a beam of radiation comprising: 
 an extreme ultraviolet radiation source for generating extreme ultraviolet radiation;    a contamination barrier for trapping contamination from said radiation source; and    a temperature control system for controlling the temperature of said contamination barrier.    
   
   
       17 . A radiation system according to  claim 16 , wherein said temperature control system comprises a temperature sensor for measuring the temperature of the contamination barrier.  
   
   
       18 . A radiation system according to  claim 16 , further comprising a heater at least partly enclosing said contamination barrier for heating the contamination barrier.  
   
   
       19 . A lithographic apparatus comprising: 
 a radiation system for generating a beam of radiation, said radiation system comprising 
 an extreme ultraviolet radiation source for generating extreme ultraviolet radiation;  
 a contamination barrier for trapping contamination from said radiation source; and  
 a temperature sensor for measuring a temperature of said contamination barrier;  
   a patterning device for patterning the beam of radiation; and    a projection system for projecting the patterned beam of radiation onto a substrate.    
   
   
       20 . A lithographic apparatus according to  claim 19 , wherein the radiation system further comprises a temperature control system for controlling the temperature of said contamination barrier.