Polarization-modulating optical element

Abstract

The invention relates to a projection system, comprising a radiation source, an illumination system operable to illuminate a structured mask, and a projection objective for projecting an image of the mask structure onto a light-sensitive substrate, wherein said projection system comprises an optical system comprising an optical axis or a preferred direction given by the direction of a light beam propagating through the optical system; the optical system comprising a temperature compensated polarization-modulating optical element described by coordinates of a coordinate system, wherein one preferred coordinate of the coordinate system is parallel to the optical axis or parallel to said preferred direction; said temperature compensated polarization-modulating optical element comprising a first and a second polarization-modulating optical element, the first and/or the second polarization-modulating optical element comprising solid and/or liquid optically active material and a profile of effective optical thickness, wherein the effective optical thickness varies at least as a function of one coordinate different from the preferred coordinate of the coordinate system, in addition or alternative the first and/or the second polarization-modulating optical element comprises solid and/or liquid optically active material, wherein the effective optical thickness is constant as a function of at least one coordinate different from the preferred coordinate of the coordinate system; wherein the first polarization-modulating optical element comprises optically active material with a specific rotation of opposite sign compared to the optically active material of the second polarization-modulating optical element.

1 . A system, comprising: 
 an illumination system;    a projection objective; and    a temperature compensated polarization-modulating optical element in the illumination system, the temperature compensated polarization-modulating optical element comprising: 
 a first polarization-modulating optical element comprising an optically active material, the first polarization-modulating optical element having a first specific rotation with a sign; and  
 a second polarization-modulating optical element comprising optically active material, the second polarization-modulating optical element having a second specific rotation with a sign opposite to the sign of the first specific rotation,  
   wherein the system is a microlithography optical system.    
   
   
       2 . The system of  claim 1 , wherein during operation, light propagates through the projection objective in a propagation direction, and wherein the first polarization-modulating optical element is a plane plate comprising optically active quartz and having a first thickness d 1  in the propagation direction, and the second polarization-modulating optical elements is a plane plate comprising optically active quartz and having a second thickness d 2  in the propagation direction.  
   
   
       3 . The system of  claim 2 , wherein an absolute value of the difference between d 1  and d 2  is less than d 1 , and the absolute value of the difference between d 1  and d 2  is less than d 2 .  
   
   
       4 . The system of  claim 2 , wherein, during operation, the first and second polarization-modulating optical elements rotate a direction of linear polarized light that enters substantially parallel to the optical axis by an angle α 1 , and an angle α 2 , respectively, wherein α 1  and α 2  meet the condition ∥α 1 |−|α 2 ∥≦0.05*(|α 1 |+|α 2 |).  
   
   
       5 . The system of  claim 4 , wherein α 1  and α 2  meet the condition ∥α 1 |−|α 2 ∥≦0.03*(|α 1 |+|α 2 |).  
   
   
       6 . The system of  claim 4 , wherein each of α, and a 2  meets the condition 160°+N*180°≦|α i |≦200°+N*180°, where N having a value of zero or greater.  
   
   
       7 . The system of  claim 2 , wherein the values of the first and the second thicknesses meet the condition |d 1 −d 2  |≦0.05*(d 1 +d 2 ).  
   
   
       8 . The system of  claim 7 , wherein the values of the first and the second thickness meet the condition |d 1 −d 2 |≦0.03*(d 1 +d 2 ).  
   
   
       9 . The system of  claim 2 , wherein the d 1  is at least 500 μm and d 2  is at least 500 μm.  
   
   
       10 . The system of  claim 1 , wherein at least one of the first and second polarization-modulating optical elements has a structured surface.  
   
   
       11 . The system of  claim 10 , wherein the structured surface has a maximum structure depth t that meets the condition t ≦0.002*d i , where i is 1 or 2.  
   
   
       12 . The system of  claim 1 , wherein the material of the first polarization-modulating optical element is an optical isomer of the material of the second polarization-modulating optical element.  
   
   
       13 . The system of anyone of  claim 1 , wherein the first and said second polarization-modulating optical elements are seamlessly jointed so that they form a unitary element.  
   
   
       14 . The system of  claim 13 , the unitary element is a diffractive optical element, a diffusion panel or a grey filter.  
   
   
       15 . The system of  claim 1 , wherein at least one polarization-modulating optical element comprises optically active or inactive material which is subjected to a magnetic field with a field component parallel to the direction of the light beam propagating through the polarization-modulating optical element.  
   
   
       16 . The system of  claim 1 , further comprising: 
 a substrate; and    an immersion medium with a refractive index different from air between the substrate and an optical element nearest to the substrate.    
   
   
       17 . A method, comprising manufacturing a micro-structured semiconductor component using the system of  claim 1 .  
   
   
       18 . An optical element, comprising: 
 a temperature compensated polarization-modulating element, comprising: 
 a first polarization-modulating optical element having a first thickness and comprising an optically active material with a first specific rotation having a sign; and  
 a second polarization-modulating optical element having a second thickness different from said first thickness, the second polarization-modulating optical element comprising an optically active material with a second specific rotation having a sign opposite the sign of the first specific rotation.  
   
   
   
       19 . The optical element of  claim 18 , wherein an absolute value of the difference of the first and the second thicknesses is less than the thickness of the first polarization-modulating optical element, and an absolute value of the difference of the first and the second thicknesses is less than the thickness of the second polarization-modulating optical element.  
   
   
       20 . A system, comprising: 
 an illumination system;    a projection objective; and    the optical element of  claim 18  in the illumination system,    wherein the system is a microlithography optical system.    
   
   
       21 . The system of  claim 20 , further comprising: 
 a substrate; and    an immersion medium with a refractive index different from air between the substrate and an optical element nearest to the substrate.    
   
   
       22 . A method, comprising manufacturing a micro-structured semiconductor component using the system according of  claim 20 .  
   
   
       23 . An optical system having an optical axis, the optical system comprising: 
 a first plane plate comprising optically active quartz, the first plate having a first thickness in the direction of the optical axis; and    a second plane plate comprising optically active quartz, the second plate having a second thickness in the direction of the optical axis, the second thickness being different from the first thickness.    
   
   
       24 . A system, comprising: 
 an illumination system;    a projection objective; and    an optical system having an optical axis, the optical system comprising: 
 a first plane plate comprising optically active quartz, the first plate having a first thickness in the direction of the optical axis; and  
 a second plane plate comprising optically active quartz, the second plate having a second thickness in the direction of the optical axis, the second thickness being different from the first thickness.