Projection Exposure System, Beam Delivery System and Method of Generating a Beam of Light

Abstract

A beam delivery system of a projection exposure system comprises a laser generating a beam of laser light from a plurality of longitudinal laser modes in a cavity, wherein light generated by a single longitudinal laser mode has an average line width λ lat , wherein the laser light of the beam has, at each of respective lateral positions of the beam, a second line width λ lat corresponding to lateral laser modes, and wherein the laser light of the beam has, when averaged over a whole cross section thereof, a line width λ b corresponding to plural lateral laser modes, and wherein λ m <λ lat <λ b , and wherein an optical delay apparatus disposed in the beam provides an optical path difference Δl, wherein 0.8 · λ 0 2 ( 2 · Δ   λ l ) < Δ   l < 1.8 · λ 0 2 ( 2 · Δλ l ) , wherein λ 0 is an average wavelength of the light of the first beam of laser light, and Δλ lat represents the second line width.

1 . (canceled) 
     
     
         2 . A beam delivery system, comprising:
 a laser for generating a beam of laser light from a plurality of longitudinal laser modes in a cavity of the laser;   an optical delay apparatus disposed in a beam path of the beam of laser light, wherein the optical delay apparatus comprises plural reflective surfaces arranged such that the beam path comprises a closed loop;   at least one phase changing element disposed in the beam path of the closed loop, wherein the phase changing element comprises a structured phase changing surface having a plurality of projections and indentations of amplitudes of more than 100 nm, and   wherein at least one of widths and heights of the projections and indentations have a random distribution.   
     
     
         3 . The beam delivery system according to  claim 2 , wherein lateral extensions of the projections and indentations are smaller than lateral extensions of laser light portions interacting with the phase changing surface and originating from single longitudinal laser modes in the cavity. 
     
     
         4 . The beam delivery system according to  claim 2 , wherein lateral extensions of the projections and indentations are smaller than lateral extensions of coherence cells of the laser light at a location of the phase changing surface. 
     
     
         5 . The beam delivery system according to  claim 2 , wherein the projections and indentations of the phase changing surface have a stepped configuration. 
     
     
         6 . The beam delivery system according to  claim 5 , wherein the projections and indentations of the phase changing surface each include surface portions oriented substantially parallel to a main surface direction of the phase changing surface. 
     
     
         7 . A beam delivery system, comprising:
 a laser for generating a beam of laser light from a plurality of longitudinal laser modes in a cavity of the laser;   an optical delay apparatus disposed in a beam path of the beam of laser light, wherein the optical delay apparatus comprises plural reflective surfaces arranged such that the beam path comprises a closed loop;   at least one phase changing element disposed in the beam path of the closed loop, wherein the phase changing element comprises a structured phase changing surface having a plurality of projections and indentations of amplitudes of more than 100 nm, and   wherein the projections and indentations of the phase changing surface have a wedge configuration.   
     
     
         8 . The beam delivery system according to  claim 7 , wherein the projections and indentations of the phase changing surface each include surface portions inclined relative to a main surface direction of the phase changing surface. 
     
     
         9 . The beam delivery system; according to  claim 8 , wherein angles of inclination of the projections are different between adjacent projections. 
     
     
         10 . The beam delivery system according to  claim 8 , wherein angles of inclination of the projections and indentations are randomly distributed. 
     
     
         11 . The beam delivery system according to  claim 7 , wherein the amplitudes of the projections and indentations are randomly distributed. 
     
     
         12 . A beam delivery system, comprising:
 a laser for generating a beam of laser light from a plurality of longitudinal laser modes in a cavity of the laser;   an optical delay apparatus disposed in a beam path of the beam of laser light, wherein the optical delay apparatus comprises plural reflective surfaces arranged such that the beam path comprises a closed loop;   at least one phase changing element comprising a phase changing surface disposed in the beam path of the closed loop; and   a surface wave generator for generating surface acoustic waves propagating across a surface portion of the phase changing surface exposed to the beam of laser light traversing the optical delay apparatus.   
     
     
         13 . The beam delivery system according to  claim 2 , wherein the phase changing surface of the phase changing element is traversed by the beam of laser light traversing the optical delay apparatus. 
     
     
         14 . The beam delivery system according to  claim 2 , wherein the phase changing surface of the phase changing element provides one of the plural reflective surfaces of the optical delay apparatus. 
     
     
         15 . The beam delivery system according to  claim 2 , wherein the optical delay apparatus comprises a semi-reflective mirror traversed by the beam of laser light traversing the optical delay apparatus. 
     
     
         16 . The beam delivery system according to  claim 15 , wherein a portion of the beam of laser light traversing the optical delay apparatus traverses the semi-reflective mirror to coincide with a beam of laser light reflected from the semi-reflective mirror. 
     
     
         17 . A beam delivery system, comprising:
 a laser for generating a beam of laser light from a plurality of longitudinal laser modes in a cavity of the laser;   an optical delay apparatus disposed in a beam path of the beam of laser light, wherein the optical delay apparatus comprises plural reflective surfaces arranged such that the beam path comprises a closed loop;   at least one phase changing element disposed in the beam path of the closed loop, wherein the phase changing element comprises a structured phase changing surface having a plurality of projections and indentations, and   wherein the optical delay element includes a prism made of a CaF 2  material having a crystal orientation such that a (100) crystal plane is oriented under an angle of 45° relative to a surface of the prism.   
     
     
         18 . A projection exposure system for imaging a patterning structure onto a substrate, the system comprising:
 the beam delivery system according to one  claim 2 ;   a projection optical system for imaging an object plane into an image plane;   a first mount for mounting the patterning structure in a region of the object plane within a beam path of the second beam of laser light generated by the beam delivery system; and   a second mount for mounting the substrate in a region of the image plane of the projection optical system.   
     
     
         19 . A projection exposure system for imaging a patterning structure onto a substrate, the system comprising:
 the beam delivery system according to one  claim 7 ;   a projection optical system for imaging an object plane into an image plane;   a first mount for mounting the patterning structure in a region of the object plane within a beam path of the second beam of laser light generated by the beam delivery system; and   a second mount for mounting the substrate in a region of the image plane of the projection optical system.   
     
     
         20 . A projection exposure system for imaging a patterning structure onto a substrate, the system comprising:
 the beam delivery system according to one  claim 12 ;   a projection optical system for imaging an object plane into an image plane;   a first mount for mounting the patterning structure in a region of the object plane within a beam path of the second beam of laser light generated by the beam delivery system; and   a second mount for mounting the substrate in a region of the image plane of the projection optical system.   
     
     
         21 . A projection exposure system for imaging a patterning structure onto a substrate, the system comprising:
 the beam delivery system according to one  claim 17 ;   a projection optical system for imaging an object plane into an image plane;   a first mount for mounting the patterning structure in a region of the object plane within a beam path of the second beam of laser light generated by the beam delivery system; and   a second mount for mounting the substrate in a region of the image plane of the projection optical system.