Polarization-modulating element, illumination optical apparatus, exposure apparatus, and exposure method

Abstract

There is disclosed a polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, the polarization-modulating element being made of an optical material with optical activity and having a circumferentially varying thickness profile.

1 . An illumination optical apparatus for illuminating a surface to be illuminated, based on illumination radiation supplied from a radiation source, comprising: 
 a polarization modulating element, which is arranged in an optical path of the illumination radiation, which is made of an optical material with optical activity, and which has a circumferentially varying thickness; and    a movable optical element arranged in an optical path between the polarization modulating element and the surface to be illuminated.    
   
   
       2 . The illumination optical apparatus according to  claim 1 , further comprising a zoom optical system, wherein the movable optical element is a part of the zoom optical system.  
   
   
       3 . The illumination optical apparatus according to  claim 1 , further comprising an axicon system, wherein movable optical element is a part of the axicon system.  
   
   
       4 . The illumination optical apparatus according to  claim 1 , wherein the polarization modulating element having sector shape elements.  
   
   
       5 . The illumination optical apparatus according to  claim 1 , wherein the polarization modulating element having a central region with no substantial optical activity.  
   
   
       6 . The illumination optical apparatus according to  claim 5 , wherein a radial size of the central region is not less than 3/10 of a radial size of an effective region of the polarization-modulating element.  
   
   
       7 . The illumination optical apparatus according to  claim 6 , wherein a radial size of the central region is not less than ⅓ of a radial size of an effective region of the polarization-modulating element.  
   
   
       8 . The illumination optical apparatus according to  claim 5 , further comprising a depolarizer arranged in an optical path in the central region.  
   
   
       9 . The illumination optical apparatus according to  claim 5 , wherein the polarization modulating element having sector shape elements.  
   
   
       10 . The illumination optical apparatus according to  claim 1 , further comprising an annular ratio changing optical system, wherein the movable optical element is a part of the annular ratio changing optical system, and wherein the annular ratio changing optical system that changes an annular ratio of a secondary radiation source formed on a pupil of the illumination optical apparatus.  
   
   
       11 . The illumination optical apparatus according to  claim 10 , wherein the polarization-modulating element is disposed in an optical path between the radiation source and the annular ratio changing optical system, the illumination optical apparatus satisfying the following conditions:  
       (10in+Δ A )/10out <0.75;  0.4<(10in+Δ A )/10out,  where 10in: an effective radius of a central region of the polarization-modulating element,    10out: an outside effective radius of the polarization-modulating element, and    ΔA: an increase of an inside radius of a beam passing through the annular ratio changing optical system.    
   
   
       12 . The illumination optical apparatus according to  claim 1 , further comprising an illumination sigma-value changing optical system, the movable optical element is a part of the illumination sigma-value changing optical system.  
   
   
       13 . The illumination optical apparatus according to  claim 1 , wherein the thickness profile is so set that radiation in a linearly polarized state with a direction of polarization substantially along a single direction, is transformed into light in a azimuthal polarization state with a direction of polarization substantially along a circumferential direction or into radiation in a radially polarized state with a direction of polarization substantially along a radial direction.  
   
   
       14 . The illumination optical apparatus according to  claim 1 , wherein the polarization modulating element having a plurality of circumferentially separated regions, wherein thicknesses of two arbitrary regions adjacent to each other among the plurality of regions are different from each other.  
   
   
       15 . The illumination optical apparatus according to  claim 14 , wherein two arbitrary regions opposite to each other among the plurality of regions have their respective thicknesses substantially equal to each other.  
   
   
       16 . The illumination optical apparatus according to  claim 1 , further comprising a polarization state controller arranged in an optical path between the radiation source and the polarization modulating element.  
   
   
       17 . The illumination optical apparatus according to  claim 16 , wherein the polarization state controller having a rotating wave plate.  
   
   
       18 . The illumination optical apparatus according to  claim 1 , wherein the optical material of the polarization modulating element is made of a crystal material whose crystallographic axis is set along a traveling direction of the incident light.  
   
   
       19 . The illumination optical apparatus according to  claim 1 , wherein the polarization modulating element is selectively positioned in an optical path of the illumination radiation or out of the optical path of the illumination radiation.  
   
   
       20 . The illumination optical apparatus according to  claim 19 , wherein the polarization modulating element is changeable to another polarization modulating element.  
   
   
       21 . The illumination optical apparatus according to  claim 1 , wherein the illumination radiation on the surface to be illuminated having an average specific polarization rate over 70%.  
   
   
       22 . The illumination optical apparatus according to  claim 21 , further comprising a polarization monitor which detects the illumination radiation.  
   
   
       23 . The illumination optical apparatus according to  claim 1 , further comprising a beam transforming element arranged in an optical path between the radiation source and the polarization modulating element.  
   
   
       24 . The illumination optical apparatus according to  claim 23 , wherein the polarization modulating element having a central region with no substantial optical activity.  
   
   
       25 . The illumination optical apparatus according to  claim 24 , wherein the beam transforming element guides a radiation from the radiation source into an effective area of the polarization modulating element.  
   
   
       26 . The illumination optical apparatus according to  claim 24 , wherein the beam transforming element guides a radiation from the radiation source into a central region of the polarization modulating element.  
   
   
       27 . The illumination optical apparatus according to  claim 23 , wherein the polarization modulating element having radial extending boundary lines.  
   
   
       28 . The illumination optical apparatus according to  claim 27 , wherein the beam transforming element guides a radiation from the radiation source into a region, which excludes the boundary line, of the polarization modulating element.  
   
   
       29 . The illumination optical apparatus according to  claim 1 , further comprising a polarization monitor which detects the illumination radiation.  
   
   
       30 . The illumination optical apparatus according to  claim 29 , further comprising a projection optical system, the polarization monitor is arranged incident side of the projection optical system.  
   
   
       31 . The illumination optical apparatus according to  claim 29 , further comprising a projection optical system, the polarization monitor is arranged exit side of the projection optical system.  
   
   
       32 . An exposure apparatus comprising the illumination optical apparatus according to  claim 1 , 
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.    
   
   
       33 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 1 , and    developing the photosensitive substrate.    
   
   
       34 . An illumination optical apparatus for illuminating a surface to be illuminated, based on illumination radiation supplied from a radiation source, comprising: 
 a polarization modulating element, which is arranged in an optical path of the illumination radiation, which is made of an optical material with optical activity, and which has a circumferentially varying thickness; and    an optical integrator arranged in an optical path between the polarization modulating element and the surface to be illuminated,    wherein the polarization modulating element having a plurality of circumferentially separated regions, wherein thicknesses of two arbitrary regions adjacent to each other among the plurality of regions are different from each other.    
   
   
       35 . An exposure apparatus comprising the illumination optical apparatus according to  claim 34 , 
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.    
   
   
       36 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 34 , and    developing the photosensitive substrate.    
   
   
       37 . An illumination optical apparatus for illuminating a surface to be illuminated, based on illumination radiation supplied from a radiation source, comprising: 
 a polarization modulating element, which is arranged in an optical path of the illumination radiation, which is made of an optical material with optical activity, and which has a circumferentially varying thickness; and    an annular ratio changing optical system, arranged in an optical path between the polarization modulating element and the surface to be illuminated, that changes an annular ratio of a secondary radiation source formed on a pupil of the illumination optical apparatus,    wherein the illumination optical apparatus satisfying the following conditions:      (10in+Δ A )/10out<0.75;    0.4 <(10in+Δ A )/10out,    where 10in: an effective radius of a central region of the polarization-modulating element,    10out: an outside effective radius of the polarization-modulating element, and    ΔA: an increase of an inside radius of a beam passing through the annular ratio changing optical system.    
   
   
       38 . The illumination optical apparatus according to  claim 37 , wherein the annular ratio changing optical system comprising an axicon system.  
   
   
       39 . The illumination optical apparatus according to  claim 38 , further comprising an illumination sigma-value changing optical system.  
   
   
       40 . An exposure apparatus comprising the illumination optical apparatus according to  claim 37 , 
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.    
   
   
       41 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 37 , and    developing the photosensitive substrate.    
   
   
       42 . An illumination optical apparatus for illuminating a surface to be illuminated, based on illumination radiation supplied from a radiation source, comprising: 
 a polarization modulating element, which is arranged in an optical path of the illumination radiation, which is made of an optical material with optical activity, and which has a circumferentially varying thickness; and    a polarization monitor, arranged in a downstream optical path of the polarization modulating element, which detects the illumination radiation.    
   
   
       43 . The illumination optical apparatus according to  claim 42 , further comprising a projection optical system, the polarization monitor is arranged incident side of the projection optical system.  
   
   
       44 . The illumination optical apparatus according to  claim 42 , further comprising a projection optical system, the polarization monitor is arranged exit side of the projection optical system.  
   
   
       45 . An exposure apparatus comprising the illumination optical apparatus according to  claim 42 , 
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.    
   
   
       46 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 42 , and    developing the photosensitive substrate.    
   
   
       47 . A polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, comprising: 
 a circumferentially varying thickness profile, and a central region with no substantial optical activity,    wherein the polarization-modulating element being made of an optical material with optical activity, and    wherein a radial size of the central region is not less than 3/10 of a radial size of an effective region of the polarization-modulating element.    
   
   
       48 . The polarization-modulating element according to  claim 47 , wherein a radial size of the central region is not less than ⅓ of a radial size of an effective region of the polarization-modulating element.  
   
   
       49 . The polarization-modulating element according to  claim 47 , further comprising a depolarizer arranged in an optical path in the central region.  
   
   
       50 . The polarization-modulating element according to  claim 47 , wherein the polarization modulating element having sector shape elements.  
   
   
       51 . An illumination optical system for illuminating a surface to be illuminated, based on illumination radiation supplied from a radiation source, comprising: 
 a polarization modulating element according to  claim 47  arranged in an optical path of the illumination radiation.    
   
   
       52 . The illumination optical system according to  claim 51 , further comprising an annular ratio changing optical system, arranged in an optical path between the polarization modulating element and the surface to be illuminated, that changes an annular ratio of a secondary radiation source formed on a pupil of the illumination optical apparatus.  
   
   
       53 . The illumination optical system according to  claim 52 , wherein the illumination optical apparatus satisfying the following conditions:  
       (10in+Δ A )/10out<0.75;  0.4<(10in+Δ A )/10out,  where 10in: an effective radius of a central region of the polarization-modulating element,    10out: an outside effective radius of the polarization-modulating element, and    ΔA: an increase of an inside radius of a beam passing through the annular ratio changing optical system.    
   
   
       54 . An exposure apparatus comprising the illumination optical apparatus according to  claim 51 , 
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.    
   
   
       55 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 51 , and    developing the photosensitive substrate.    
   
   
       56 . A polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, and for using with an illumination optical apparatus having an annular ratio changing optical system, comprising: 
 a circumferentially varying thickness profile, and a central region with no substantial optical activity,    wherein the polarization-modulating element being made of an optical material with optical activity,    wherein the annular ratio changing optical system, arranged in an optical path between the polarization modulating element and a surface to be illuminated, that changes an annular ratio of a secondary radiation source formed on a pupil of the illumination optical apparatus, and    wherein the illumination optical apparatus satisfying the following conditions:      (10in+Δ A )/10out<0.75;  0.4<(10in+Δ A )/10out,    where 10in: an effective radius of the central region of the polarization-modulating element,    10out: an outside effective radius of the polarization-modulating element, and    ΔA: an increase of an inside radius of a beam passing through the annular ratio changing optical system.    
   
   
       57 . The polarization-modulating element according to  claim 56 , wherein a radial size of the central region is not less than 3/10 of a radial size of an effective region of the polarization-modulating element.  
   
   
       58 . The polarization-modulating element according to  claim 57 , wherein a radial size of the central region is not less than ⅓ of a radial size of an effective region of the polarization-modulating element.  
   
   
       59 . The polarization-modulating element according to  claim 56 , further comprising a depolarizer arranged in an optical path in the central region.  
   
   
       60 . The polarization-modulating element according to  claim 56 , wherein the polarization modulating element having sector shape elements.  
   
   
       61 . A polarization monitor for detecting a beam in an optical path of an illumination optical apparatus which illuminates a surface to be illuminated base on a radiation from an radiation source, comprising: 
 an optical element arranged in an optical path of the beam; and    a detector which detect the beam through the optical element,    wherein the beam which enters the optical element passes through a polarization-modulating element and an optical integrator,    wherein the polarization-modulating element being made of an optical material with optical activity, and having a circumferentially varying thickness profile, and    wherein the optical integrator arranged in an optical path between the polarization-modulating element and the surface to be illuminated.    
   
   
       62 . The polarization monitor according to  claim 61 , wherein the polarization monitor detects a beam which travels toward a projection optical system.  
   
   
       63 . The polarization monitor according to  claim 61 , wherein the polarization monitor detects a beam via a projection optical system.  
   
   
       64 . An exposure apparatus for projecting a predetermined pattern onto a photosensitive substrate, comprising: 
 an illumination optical apparatus which illuminates the predetermined pattern, and    the polarization monitor according to  claim 61 .    
   
   
       65 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus,    detecting a radiation which is used under the projecting step, and    developing the photosensitive substrate.    
   
   
       66 . A polarization monitoring method comprising the steps of: 
 receiving a radiation from a radiation source through a polarization-modulating element and an optical integrator,    detecting the radiation, and    analyzing a detecting result,    wherein the polarization-modulating element being made of an optical material with optical activity, and having a circumferentially varying thickness profile, and    wherein the optical integrator arranged in an optical path between the polarization-modulating element and a surface to be illuminated.    
   
   
       67 . The polarization monitoring method according to  claim 66 , wherein detecting a beam which travels toward a projection optical system, in the detecting step.  
   
   
       68 . The polarization monitoring method according to  claim 66 , wherein detecting a beam via a projection optical system, in the detecting step.  
   
   
       69 . A method of adjusting an optical apparatus comprising: 
 supplying a radiation to the optical apparatus;    detecting a radiation through the optical apparatus using the method according to  claim 66;  and    adjusting the optical apparatus based on an analyzing result.    
   
   
       70 . The adjusting method according to  claim 69 , wherein the adjusting step adjusts the polarization-modulating element.  
   
   
       71 . An exposure apparatus for projecting a predetermined pattern onto a photosensitive substrate, comprising: 
 an illumination optical apparatus having the optical apparatus adjusted by the method according to  claim 69 , and    a substrate holder which hold the photosensitive substrate.    
   
   
       72 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the optical apparatus adjusted by the method according to  claim 69 , and    developing the photosensitive substrate.    
   
   
       73 . A polarization monitor for detecting a beam in an optical path of an exposure apparatus which projects a predetermined pattern onto a photosensitive substrate positioned on a main surface, comprising: 
 an optical element arranged near the main surface; and    a detector which detect the beam through the optical element,    wherein the beam which enters the optical element passes through a polarization-modulating element and an optical integrator,    wherein the polarization-modulating element being made of an optical material with optical activity, and having a circumferentially varying thickness profile, and    wherein the optical integrator arranged in an optical path between the polarization-modulating element and the surface to be illuminated.    
   
   
       74 . An exposure apparatus for projecting a predetermined pattern onto a photosensitive substrate, comprising: 
 the polarization monitor according to  claim 73 , and    a substrate holder which hold the photosensitive substrate.    
   
   
       75 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the exposure apparatus according to  claim 74 , and    developing the photosensitive substrate.    
   
   
       76 . A polarization monitoring method comprising the steps of: 
 receiving a radiation from a radiation source through a polarization-modulating element and an optical integrator at a main surface,    detecting the radiation, and    analyzing a detecting result,    wherein the polarization-modulating element being made of an optical material with optical activity, and having a circumferentially varying thickness profile,    wherein the optical integrator arranged in an optical path between the polarization-modulating element and a surface to be illuminated, and    wherein a predetermined pattern on the surface to be illuminated is projected onto a photosensitive substrate positioned on the main surface.    
   
   
       77 . A method of adjusting an optical apparatus comprising: 
 supplying a radiation to the optical apparatus;    detecting a radiation through the optical apparatus using the method according to  claim 76;  and    adjusting the optical apparatus based on an analyzing result.    
   
   
       78 . The adjusting method according to  claim 77 , wherein the adjusting step adjusts the polarization-modulating element.  
   
   
       79 . An exposure apparatus for projecting a predetermined pattern onto a photosensitive substrate, comprising: 
 an illumination optical apparatus having the optical apparatus adjusted by the method according to  claim 78 , and    a substrate holder which hold the photosensitive substrate.    
   
   
       80 . A device manufacturing method comprising the steps of: 
 projecting a predetermined pattern onto a photosensitive substrate, using the optical apparatus adjusted by the method according to  claim 77 , and    developing the photosensitive substrate.    
   
   
       81 . An illumination optical apparatus for illuminating a surface to be illuminated, based on illumination light supplied from a light source, 
 the illumination optical apparatus satisfying the following relations:        RSPh (Ave)>70%, and  RSPv (Ave)>70%,    where RSPh(Ave) is an average specific polarization rate about polarization in a first direction in a predetermined effective light source region in a light intensity distribution formed in an illumination pupil plane of the illumination optical apparatus or in a plane conjugate with the illumination pupil plane, and RSPv(Ave) an average specific polarization rate about polarization in a second direction in the predetermined effective light source region,    wherein        RSPh (Ave)= Ix (Ave)/( Ix+Iy )Ave    RSPv (Ave)= Iy (Ave)/( Ix+Iy )Ave,    where Ix(Ave) is an average intensity of a polarization component in the first direction in a bundle of rays passing through the predetermined effective light source region and arriving at a point on an image plane, Iy(Ave) an average intensity of a polarization component in the second direction in the bundle of rays passing through the predetermined effective light source region and arriving at a point on the image plane, and (Ix+Iy)Ave an average intensity of an entire beam passing through the predetermined effective light source region.    
   
   
       82 . An exposure apparatus comprising the illumination optical apparatus as defined in  claim 81 , wherein a pattern of a mask is projected onto a photosensitive substrate through the illumination optical apparatus.  
   
   
       83 . An exposure method of projecting a pattern of a mask onto a photosensitive substrate, using the illumination optical apparatus as defined in  claim 81 .  
   
   
       84 . A method of producing a polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, comprising: 
 a step of preparing an optical material with optical activity; and    a step of providing the optical material with a circumferentially varying thickness profile.    
   
   
       85 . The production method of the polarization-modulating element according to  claim 84 , wherein the thickness profile is so set that light in a linearly polarized state with a direction of polarization substantially along a single direction, is transformed into light in a azimuthal polarization state with a direction of polarization substantially along a circumferential direction or into light in a radially polarized state with a direction of polarization substantially along a radial direction.  
   
   
       86 . The production method of the polarization-modulating element according to  claim 85 , wherein the step of providing the circumferentially varying thickness profile is to provide such a thickness profile that thicknesses of two arbitrary regions adjacent to each other among a plurality of circumferentially separated regions are different from each other.  
   
   
       87 . The production method of the polarization-modulating element according to  claim 85 , wherein two arbitrary regions opposite to each other among the plurality of regions have their respective angles of optical rotation substantially equal to each other.  
   
   
       88 . The production method of the polarization-modulating element according to  claim 87 , wherein said two arbitrary regions opposite to each other have their respective thicknesses substantially equal to each other.  
   
   
       89 . The production method of the polarization-modulating element according to  claim 84 , wherein the step of providing the circumferentially varying thickness profile is to provide a thickness profile circumferentially varying in a substantially continuous manner.  
   
   
       90 . The production method of the polarization-modulating element according to  claim 84 , wherein the step of preparing the optical material with optical activity is to set the optical material so that a crystallographic axis thereof coincides with a traveling direction of the incident light.