Microlithographic projection exposure apparatus and measuring device for a projection lens

Abstract

A microlithographic projection exposure apparatus includes a projection lens that is configured for immersion operation. For this purpose an immersion liquid is introduced into an immersion space that is located between a last lens of the projection lens on the image side and a photosensitive layer to be exposed. To reduce fluctuations of refractive index resulting from temperature gradients occurring within the immersion liquid, the projection exposure apparatus includes heat transfer elements that heat or cool partial volumes of the immersion liquid so as to achieve an at least substantially homogenous or at least substantially rotationally symmetric temperature distribution within the immersion liquid.

1 . A microlithographic projection exposure apparatus, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid,    d) a heat transfer element for selectively varying the temperature in a partial volume of the immersion space so as to achieve an at least substantially homogenous or at least substantially rotationally symmetric temperature distribution within the immersion liquid.    
   
   
       2 . The projection exposure apparatus according to  claim 1 , wherein the heat transfer element is arranged in the immersion space in such a way that it comes into contact with the immersion liquid during immersion operation.  
   
   
       3 . The projection exposure apparatus according to  claim 2 , wherein the heat transfer element is a heating wire.  
   
   
       4 . The projection exposure apparatus according to  claim 1 , wherein the immersion space is laterally delimited by a wall in which the heat transfer element is arranged.  
   
   
       5 . The projection exposure apparatus according to  claim 1 , wherein the heat transfer element is a Peltier element.  
   
   
       6 . The projection exposure apparatus according to  claim 1 , wherein the heat transfer element is arranged at a distance from the immersion space so that heat can be exchanged by thermal radiation between the heat transfer element and the partial volume.  
   
   
       7 . The projection exposure apparatus according to  claim 6 , comprising a directive optical element that changes the direction of the thermal radiation and is arranged between the heat transfer element and the immersion space.  
   
   
       8 . The projection exposure apparatus according to  claim 7 , wherein the directive optical element has a positive refractive power.  
   
   
       9 . The projection exposure apparatus according to  claim 6 , wherein the heat transfer element is a planar radiator that is configured for being heated or cooled.  
   
   
       10 . The projection exposure apparatus according to  claim 6 , comprising a thermal sensor for measuring the temperature of the heat transfer element.  
   
   
       11 . The projection exposure apparatus according to  claim 10 , wherein the thermal sensor is connected to a control device which adjusts a heating or cooling output of the heat transfer element.  
   
   
       12 . The projection exposure apparatus according to  claim 1 , wherein the heat transfer element is arranged in a wafer stage for positioning a carrier on which the photosensitive layer is applied.  
   
   
       13 . The projection exposure apparatus according to  claim 12 , wherein the heat transfer element has substantially the same symmetry as a light field illuminated on the photosensitive layer.  
   
   
       14 . The projection exposure apparatus according to  claim 12 , wherein the heat transfer element includes a plurality of conduits contained in the wafer stage for conducting a heating or cooling medium through said wafer stage.  
   
   
       15 . The projection exposure apparatus according to  claim 1 , wherein the immersion space is formed between a last optical element of the projection lens on the image side and the photosensitive layer and  
   
   
       16 . A microlithographic projection exposure apparatus, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid,    d) an evaporation barrier which 
 at least partially surrounds the immersion space,  
 is arranged on an underside of the projection lens and  
 extends towards the photosensitive layer.  
   
   
   
       17 . The projection exposure apparatus according to  claim 16 , wherein the evaporation barrier includes a plurality of at least approximately concentric rings that are arranged at a distance from one another.  
   
   
       18 . A projection exposure apparatus for microlithography, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid,    d) an outer chamber, which surrounds the immersion space and is in fluid communication therewith, is configured to become enriched with a vapor phase of the immersion liquid.    
   
   
       19 . The projection exposure apparatus according to  claim 18 , comprising a supply device for feeding a vapor phase of the immersion liquid into the outer chamber.  
   
   
       20 . The projection exposure apparatus according to  claim 18 , wherein the pressure of the vapor phase of the immersion liquid in the outer chamber is so adjustable that it is at least approximately equal to the saturation vapor pressure of the vapor phase of the immersion liquid at the temperature prevailing in the outer chamber.  
   
   
       21 . The projection exposure apparatus according to  claim 1 , wherein the heat transfer element comprises a plurality of outlets that are configured to supply immersion liquid to the immersion space, wherein the outlets have at least one outlet property that is independently controllable for each outlet.  
   
   
       22 . The projection exposure apparatus according to  claim 21 , wherein the outlet property is the volume of immersion liquid flowing out of an outlet per unit time.  
   
   
       23 . The projection exposure apparatus according to  claim 21  wherein the outlet property is the temperature of immersion liquid flowing out of an outlet.  
   
   
       24 . The projection exposure apparatus according to  claim 23 , wherein each outlet comprises heating and/or cooling elements arranged within a wall of the outlet.  
   
   
       25 . The projection exposure apparatus according to  claim 1 , comprising a manipulator for correcting residual imaging aberrations of the projection lens caused by deviations from the at least substantially homogenous or at least substantially rotationally symmetric temperature distribution within the immersion liquid.  
   
   
       26 . The projection exposure apparatus according to  claim 25 , wherein the manipulator comprises an actuator for tilting, deforming or displacing an optical element contained in the projection lens.  
   
   
       27 . The projection exposure apparatus according to  claim 25 , wherein the manipulator comprises gas pressure changing means for changing a gas pressure within at least a part of the projection lens.  
   
   
       28 . A measuring device for determining the imaging characteristics of a projection lens of a microlithographic exposure apparatus, comprising: 
 a) a test optics component that is arranged on the image side of the projection lens,    b) an immersion liquid for filling an immersion space formed between a last optical element of the projection lens on the image side and the test optics component, and    c) a heat transfer element for selectively changing the temperature in a partial volume of the immersion space.    
   
   
       29 . The measuring device according to  claim 28 , wherein the test optics component includes a first zone being at least partially transparent to light, wherein said first zone is at least partially surrounded by a second zone consisting of a material that has a higher thermal conductivity than the material of which the fist zone consists.  
   
   
       30 . The measuring device according to  claim 29 , wherein the test optics component is a pinhole mask of a point diffraction interferometer.  
   
   
       31 . A method for producing a projection lens for a microlithographic projection exposure apparatus, comprising the following steps: 
 a) assembling a projection lens from a plurality of optical elements;    b) installing the projection lens in a measuring device which includes a test optics component that is arranged on the image side of the projection lens;    c) introducing an immersion liquid into an immersion space formed between a last optical element of the projection lens on the image side and the test optics component;    d) selectively varying the temperature of the immersion liquid in a partial volume of the immersion space by means of a heat transfer element;    e) determining the imaging characteristics of the projection lens;    f) adjusting the position of at least one optical element of the projection lens.    
   
   
       32 . A projection lens produced using a method according to  claim 31 .  
   
   
       33 . A method for the microlithographic production of a microstructured component, comprising the following steps: 
 a) providing a projection lens;    b) arranging a mask in an object plane of the projection lens;    c) introducing an immersion liquid into an immersion space;    d) selectively varying the temperature of the immersion liquid in a partial volume of the immersion space by means of a heat transfer element so as to achieve an at least substantially homogenous or at least substantially rotationally symmetric temperature distribution within the immersion liquid;    e) projecting the mask onto a photosensitive layer.    
   
   
       34 . The method according to  claim 31 , wherein the immersion liquid is circulated in the immersion space by means of a pump solely during time intervals in which no projection takes place.  
   
   
       35 . A microstructured component that it is produced by a method according to  claim 33 .  
   
   
       36 . A microlithographic projection exposure apparatus, comprising: 
 a) a projection lens,    b) an immersion liquid,    c) a heat transfer element that selectively varies the temperature in a partial volume of the immersion liquid.    
   
   
       37 . The apparatus of  claim 36 , wherein the heat transfer element is configured and controlled such that it achieves an at least substantially homogenous or at least substantially rotationally symmetric temperature distribution within the immersion liquid.  
   
   
       38 . A microlithographic projection exposure apparatus, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid, wherein the immersion space is delimited by a wall in which an aperture for a pipe leading into the immersion space is provided, the dimensions of the aperture being larger than the external dimensions of the pipe by an amount such that immersion liquid can enter a gap remaining between the pipe and the wall but cannot flow out of said gap because of adhesion forces.    
   
   
       39 . A microlithographic projection exposure apparatus, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid,    d) a container for immersion liquid, wherein said container is arranged above the immersion space and is in fluid communication therewith so that immersion liquid is allowed to flow from the container into the immersion space solely as a result of gravity.    
   
   
       40 . A microlithographic projection exposure apparatus, comprising: 
 a) an illumination system for generating projection light,    b) a projection lens for imaging a mask on a photosensitive layer, said projection lens comprising a plurality of optical elements, and    c) an immersion space that is configured to be filled with an immersion liquid,    d) a detector for detecting immersion liquid.    
   
   
       41 . The projection exposure apparatus according to  claim 40 , wherein the detector determines whether immersion liquid leaves a predefined closed area.  
   
   
       42 . The projection exposure apparatus according to  claim 41 , wherein the closed area is arranged on the photosensitive layer below the projection lens.  
   
   
       43 . The projection exposure apparatus according to  claim 40 , wherein the detector includes two conductors disposed substantially parallel to one another.  
   
   
       44 . The projection exposure apparatus according to  claim 43 , wherein the detector includes a measuring circuit for measuring the capacitance between the conductors.  
   
   
       45 . A microlithographic projection exposure apparatus, comprising: 
 a) a projection lens that projects an image of a mask onto a photosensitive layer which is applied to a carrier,    b) a stage for positioning the carrier relative to the projection lens,    c) an immersion liquid,    d) a temperature sensor that detects the temperature of the immersion liquid, wherein said temperature sensor is received in the stage.    
   
   
       46 . A method for the microlithographic production of a microstructured component, comprising the following steps: 
 a) providing a projection lens;    b) arranging a mask in an object plane of the projection lens;    c) introducing an immersion liquid into an immersion space;    d) measuring the temperature or the refractive index of the immersion liquid;    e) correcting imaging aberrations depending on data measured in step d).    f) projecting the mask onto a photosensitive layer.    
   
   
       47 . The method of  claim 46 , wherein step e) is carried out simultaneously with step f).