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 form 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  10 in: an effective radius of a central region of the polarization-modulating element,     10 out: 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 clam  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 form 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 clam  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 form 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  10 in: an effective radius of a central region of the polarization-modulating element,     10 out: 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 clam  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 . 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.   
   
   
       43 . The polarization-modulating element according to  claim 42 , 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. 
   
   
       44 . The polarization-modulating element according to  claim 42 , further comprising a depolarizer arranged in an optical path in the central region. 
   
   
       45 . The polarization-modulating element according to  claim 42 , wherein the polarization modulating element having sector shape elements. 
   
   
       46 . An illumination optical system for illuminating a surface to be illuminated, based on illumination radiation supplied form a radiation source, comprising:
 a polarization modulating element according to  claim 42  arranged in an optical path of the illumination radiation.   
   
   
       47 . The illumination optical system according to  claim 46 , 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. 
   
   
       48 . The illumination optical system according to  claim 47 , wherein the illumination optical apparatus satisfying the following conditions:
   (10in+Δ A )/10out<0.75;     0.4<(10in+Δ A )/10out,   where  10 in: an effective radius of a central region of the polarization-modulating element,     10 out: 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.   
   
   
       49 . An exposure apparatus comprising the illumination optical apparatus according to clam  46 ,
 wherein a predetermined pattern is projected onto a photosensitive substrate through the illumination optical apparatus.   
   
   
       50 . A device manufacturing method comprising the steps of:
 projecting a predetermined pattern onto a photosensitive substrate, using the illumination optical apparatus according to  claim 46 , and   developing the photosensitive substrate.   
   
   
       51 . 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  10 in: an effective radius of the central region of the polarization-modulating element,     10 out: 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.   
   
   
       52 . The polarization-modulating element according to  claim 51 , 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. 
   
   
       53 . The polarization-modulating element according to  claim 52 , 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. 
   
   
       54 . The polarization-modulating element according to  claim 51 , further comprising a depolarizer arranged in an optical path in the central region. 
   
   
       55 . The polarization-modulating element according to  claim 51 , wherein the polarization modulating element having sector shape elements. 
   
   
       56 . 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.   
   
   
       57 . The polarization monitor according to  claim 56 , wherein the polarization monitor detects a beam which travels toward a projection optical system. 
   
   
       58 . The polarization monitor according to  claim 56 , wherein the polarization monitor detects a beam via a projection optical system. 
   
   
       59 . 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 56 .   
   
   
       60 . 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.   
   
   
       61 . 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.   
   
   
       62 . The polarization monitoring method according to  claim 61 , wherein detecting a beam which travels toward a projection optical system, in the detecting step. 
   
   
       63 . The polarization monitoring method according to  claim 61 , wherein detecting a beam via a projection optical system, in the detecting step. 
   
   
       64 . 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 61 ; and   adjusting the optical apparatus based on an analyzing result.   
   
   
       65 . The adjusting method according to  claim 64 , wherein the adjusting step adjusts the polarization-modulating element. 
   
   
       66 . 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 64 , and   a substrate holder which hold the photosensitive substrate.   
   
   
       67 . 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 64 , and   developing the photosensitive substrate.   
   
   
       68 . 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.   
   
   
       69 . An exposure apparatus for projecting a predetermined pattern onto a photosensitive substrate, comprising:
 the polarization monitor according to  claim 68 , and   a substrate holder which hold the photosensitive substrate.   
   
   
       70 . A device manufacturing method comprising the steps of:
 projecting a predetermined pattern onto a photosensitive substrate, using the exposure apparatus according to  claim 69 , and   developing the photosensitive substrate.   
   
   
       71 . 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.   
   
   
       72 . The production method of the polarization-modulating element according to  claim 71 , 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. 
   
   
       73 . The production method of the polarization-modulating element according to  claim 72 , 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. 
   
   
       74 . The production method of the polarization-modulating element according to  claim 72 , 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. 
   
   
       75 . The production method of the polarization-modulating element according to  claim 74 , wherein said two arbitrary regions opposite to each other have their respective thicknesses substantially equal to each other. 
   
   
       76 . The production method of the polarization-modulating element according to  claim 71 , wherein the step of providing the circumferentially varying thickness profile is to provide a thickness profile circumferentially varying in a substantially continuous manner. 
   
   
       77 . The production method of the polarization-modulating element according to  claim 71 , 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.