Lithographic apparatus and device manufacturing method

Abstract

A system and method are used to direct a radiation beam to illuminate non-perpendicularly a patterning array of individually controllable elements used for patterning the radiation beam. The individually controllable elements can change a telecentricity of the radiation beam. Projection of the radiation beam onto the individually controllable elements can be by a concave mirror or use a folding mirror placed in an object field of the individually controllable elements. Alternatively, the individually controllable elements can change the optical axis of the radiation beam.

1 . A lithographic apparatus, comprising: 
 an illumination system that conditions a radiation beam;    a patterning array comprising individually controllable elements to pattern; and    a projection system that projects the patterned radiation beam onto a target portion of a substrate, wherein the radiation beam is arranged to illuminate the patterning array non-perpendicularly.    
   
   
       2 . The apparatus of  claim 1 , wherein the patterning array changes a telecentricity of the radiation beam.  
   
   
       3 . The apparatus of  claim 2 , further comprising a concave optical element that projects the radiation beam onto the patterning array.  
   
   
       4 . The apparatus of  claim 3 , wherein the concave optical element is formed by a plurality of optical elements, each having a common optical axis.  
   
   
       5 . The apparatus of  claim 3 , wherein the concave optical element is a mirror.  
   
   
       6 . The apparatus of  claim 3 , wherein the concave optical element is annular, having a central aperture arranged along the optical axis of the radiation beam and allowing the patterned radiation beam to pass through the concave optical element without interference.  
   
   
       7 . The apparatus of  claim 6 , wherein the illumination system projects the radiation beam as a plane parallel radiation beam onto the concave optical element.  
   
   
       8 . The apparatus of  claim 6 , wherein the illumination system projects the radiation beam as a divergent radiation beam onto the concave optical element.  
   
   
       9 . The apparatus of  claim 6 , further comprising a folding mirror for projecting the radiation beam onto the concave optical element.  
   
   
       10 . The apparatus of  claim 6 , wherein the radiation beam is arranged such that the object field for the patterning array is farther from the optical axis than is an image field of the patterning array.  
   
   
       11 . The apparatus of  claim 1 , further comprising a folding mirror or prism that directs the radiation beam towards the patterning array.  
   
   
       12 . The apparatus of  claim 11 , wherein the patterning array is arranged such that the image pupil of the patterning array is farther from the individually controllable elements than from the folding mirror or prism.  
   
   
       13 . The apparatus of  claim 11 , further comprising an optical element with positive optical power arranged close to the patterning array to refract both the object field and the image field.  
   
   
       14 . The apparatus of  claim 11 , wherein the folding mirror or prism is arranged to change the optical axis of the radiation beam.  
   
   
       15 . The apparatus of  claim 11 , further comprising an optical element with negative optical power arranged in the object field of the patterning array, but not in the image field thereof.  
   
   
       16 . The apparatus of  claim 1 , wherein the patterning array is arranged to change the optical axis of the radiation beam.  
   
   
       17 . The apparatus of  claim 16 , further comprising a reflecting device constructed to project the radiation beam onto the patterning array.  
   
   
       18 . The apparatus of  claim 17 , wherein a plurality of the reflecting elements form the reflecting device.  
   
   
       19 . The apparatus of  claim 18 , wherein there is a reflecting element corresponding to each individually controllable element or group thereof.  
   
   
       20 . The apparatus of  claim 16 , wherein the optical axes of the individually controllable elements are arranged at an angle of from about 0.05 to about 0.2 rad to the optical axis of the incoming radiation beam.  
   
   
       21 . The apparatus of  claim 16 , wherein the individually controllable elements are arranged to change the optical axis of the radiation beam after reflection by the individually controllable elements to be different from the optical axis of the radiation beam prior to reflection by the individually controllable elements.  
   
   
       22 . The apparatus of  claim 16 , further comprising aspheric optical elements for projecting the radiation beam.  
   
   
       23 . The apparatus of  claim 22 , wherein the aspheric optical elements form a Schwarzschild 2-mirror design.  
   
   
       24 . The apparatus of  claim 22 , wherein the aspheric optical elements form a Ritchey-Chrétien design.  
   
   
       25 . The apparatus of  claim 1 , wherein the illumination system comprises: 
 a telecentric optical system for uniformly illuminating a plane; and    a non-telecentric relay system for projecting an image of the plane onto the patterning array.    
   
   
       26 . The apparatus of  claim 25 , wherein the relay system comprises an apertured folding mirror.  
   
   
       27 . The apparatus of  claim 1 , comprising a plurality of patterning arrays and a corresponding plurality of coupling mirrors, each coupling mirror being arranged to direct radiation selectively reflected by a respective one of the patterning arrays into the projection system.  
   
   
       28 . The apparatus of  claim 27 , wherein the coupling mirrors are arranged such that viewed from the projection system, the patterning arrays are arranged in a virtual array that is denser than the actual arrangement of the patterning arrays.  
   
   
       29 . The apparatus of  claim 27 , wherein the coupling mirrors are arranged such that all beam paths from the coupling mirrors to the projection system pass through a single aperture in a support structure for the patterning arrays.  
   
   
       30 . The apparatus of  claim 27 , wherein the coupling mirrors are arranged such that beam paths from the coupling mirrors to the projection system pass through a plurality if apertures in a support structure for the patterning arrays.  
   
   
       31 . The apparatus of  claim 27 , wherein the coupling mirrors are arranged such that the angles of incidence of radiation on the patterning arrays and the coupling mirrors are near perpendicular.  
   
   
       32 . The apparatus of  claim 27 , further comprising a second plurality of coupling mirrors for directing radiation from the illumination system to respective ones of the patterning arrays.  
   
   
       33 . A device manufacturing method, comprising: 
 illuminating a patterning array non-perpendicularly with a beam radiation beam;    patterning the beam using the patterning array; and    projecting the patterned beam of radiation onto a substrate.    
   
   
       34 . The method of  claim 33 , further comprising changing an optical axis of the radiation beam using the patterning array.  
   
   
       35 . The method according to  claim 33 , further comprising changing a telecentricity of the radiation beam using the patterning array.