Contamination barrier and lithographic apparatus comprising same

Abstract

A rotatable contamination barrier is disclosed that has a plurality of closely packed blades configured to trap contaminant material coming from a radiation source. The blades are radially oriented relative to a central rotation axis of the contamination barrier. The blades comprise a metal compound having crystals oriented generally radially relative to the central rotation axis.

1 - 15 . (canceled) 
   
   
       16 . A method of providing a rotatable contamination barrier, the method comprising:
 axially compressing a rod of metal compound material having orientable crystals by forging so that the rod starts to expand in an expansion zone and the crystals radially align in the expansion zone; and   cutting a blade structure in the expansion zone around a central zone, so as to provide the contamination barrier.   
   
   
       17 . The method of  claim 16 , wherein the forging is carried out at a temperature above 800° C. 
   
   
       18 . The method of  claim 16 , wherein the cutting is performed by arcing, electrochemical machining, or both. 
   
   
       19 . A method of providing a rotatable contamination barrier, the method comprising:
 providing a folded blade shape from a rolled sheet of metal compound material having a uniform crystal orientation oriented along a rolling direction, the fold oriented transverse to the rolling direction;   engaging the folds by mounting elements to hold the folds parallel to a central rotation axis of the contamination barrier; and   orienting the blades radially relative to the rotation axis, so as to provide the contamination barrier.   
   
   
       20 . A rotatable contamination barrier obtainable by the method of  claim 16 . 
   
   
       21 . (canceled) 
   
   
       22 . A rotatable contamination barrier obtainable by the method of  claim 19 . 
   
   
       23 . The method of  claim 16 , wherein the metal compound has a creep strength of more than 100 MPa for a production of 1 percent creep in 1000 hours, at a temperature of 800° C. 
   
   
       24 . The method of  claim 16 , wherein the metal compound is a molybdenum metal compound or an alloy thereof. 
   
   
       25 . The method of  claim 24 , wherein the molybdenum alloy comprises hafnium, zirconium, titanium, lantanum, cobalt, an oxide of any of the foregoing, a carbide of any of the foregoing, or any combination of the foregoing. 
   
   
       26 . The method of  claim 24 , wherein the molybdenum alloy comprises molybdenum, carbon, and at least one selected out of the group of titanium, zirconium or hafnium. 
   
   
       27 . The method of  claim 24 , wherein the molybdenum alloy comprises an oxygen dispersed strengthened (ODS) reinforcement material. 
   
   
       28 . The method of  claim 16 , wherein the metal compound comprises a nickel, chromium, cobalt, molybdenum, aluminum, and titanium alloy. 
   
   
       29 . The method of  claim 16 , wherein the metal compound comprises at least one selected out of the group of tantalum, hafnium, titanium, zirconium, molybdenum, lantanum, cobalt, iron, nickel, chromium, aluminum, tungsten, an oxide of any of the foregoing, or a carbide of any of the foregoing. 
   
   
       30 . The method of  claim 16 , wherein a blade of the blade structure has an increased thickness at a position closer to the central zone than at a position further away from the central zone. 
   
   
       31 . The method of  claim 19 , wherein the metal compound has a creep strength of more than 100 MPa for a production of 1 percent creep in 1000 hours, at a temperature of 800° C. 
   
   
       32 . The method of  claim 19 , wherein the metal compound is a molybdenum metal compound or an alloy thereof. 
   
   
       33 . The method of  claim 32 , wherein the molybdenum alloy comprises hafnium, zirconium, titanium, lantanum, cobalt, an oxide of any of the foregoing, a carbide of any of the foregoing, or any combination of the foregoing. 
   
   
       34 . The method of  claim 32 , wherein the molybdenum alloy comprises molybdenum, carbon, and at least one selected out of the group of titanium, zirconium or hafnium. 
   
   
       35 . The method of  claim 32 , wherein the molybdenum alloy comprises an oxygen dispersed strengthened (ODS) reinforcement material. 
   
   
       36 . The method of  claim 19 , wherein the metal compound comprises a nickel, chromium, cobalt, molybdenum, aluminum, and titanium alloy. 
   
   
       37 . The method of  claim 19 , wherein the metal compound comprises at least one selected out of the group of tantalum, hafnium, titanium, zirconium, molybdenum, lantanum, cobalt, iron, nickel, chromium, aluminum, tungsten, an oxide of any of the foregoing, or a carbide of any of the foregoing.