JP2007048871A - Illuminating optical device, exposure device and manufacturing method for micro-device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating optical device capable of partially correcting the polarized state of an illuminating light. <P>SOLUTION: The illuminating optical device illuminates a surface M to be irradiated by the illuminating light emitted from a light source 1. The illuminating optical device has a correction member 88 partially correcting the polarized state of the illuminating light by imparting a specified stress. In the illuminating optical device, the correction member 88 is arranged in a place where an illuminating pupil is formed in an optical path from the light source 1 to the surface to be irradiated M, or a section near the place. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination optical apparatus used in an exposure apparatus for manufacturing a microdevice such as a semiconductor element, a liquid crystal display element, and a thin film magnetic head in a lithography process, an exposure apparatus including the illumination optical apparatus, and the exposure apparatus. The present invention relates to a method for manufacturing a microdevice.

  Conventionally, in an exposure apparatus, a light beam emitted from a light source forms a secondary light source as a substantial surface light source composed of a large number of light sources through a fly-eye lens (or a microlens array, etc.) as an optical integrator. To do. The light flux from the secondary light source (generally, the illumination pupil distribution formed in or near the illumination pupil of the illumination optical device) is limited through an aperture stop disposed in the vicinity of the rear focal plane of the fly-eye lens. Then, it enters the condenser lens.

  The light beam condensed by the condenser lens illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask pattern forms an image on the wafer via the projection optical system. Thus, the mask pattern is projected and exposed (transferred) on the wafer. Here, the pattern formed on the mask is highly integrated. In order to accurately transfer the fine pattern onto the wafer, it is indispensable to obtain a uniform illuminance distribution according to a predetermined polarization state on the wafer. In order to realize illumination conditions suitable for transferring a fine pattern in an arbitrary direction with high accuracy, there is an illumination optical device including an optical element that converts a light beam into a circumferential polarization state (see Patent Document 1). .

WO2005 / 050718

  By the way, in order to transfer a fine pattern in an arbitrary direction with high accuracy, the polarization state of the light beam on the photosensitive substrate needs to be an accurate circumferential polarization state, but the process until the light beam reaches the photosensitive substrate. However, in some cases, the polarization state is partially changed by passing through the optical member, and the accurate circumferential polarization state cannot be maintained.

  An object of the present invention is to provide an illumination optical apparatus capable of locally correcting the polarization state of illumination light, an exposure apparatus provided with the illumination optical apparatus, and a method of manufacturing a micro device using the exposure apparatus. is there.

  The illumination optical device according to the present invention includes a correction member that locally corrects the polarization state of the illumination light by applying a predetermined stress in the illumination optical device that illuminates the irradiated surface with the illumination light emitted from the light source. The correction member is arranged at or near a position where an illumination pupil is formed in an optical path from the light source to the irradiated surface.

  According to the illumination optical apparatus of the present invention, the polarization state of the illumination light can be locally corrected effectively by the correction member.

  The exposure apparatus of the present invention is an exposure apparatus for exposing a predetermined pattern illuminated by illumination light emitted from a light source onto a photosensitive substrate via a projection optical system, and includes the illumination optical apparatus of the present invention. And

  According to the exposure apparatus of the present invention, since the polarization state of the illumination light can be locally corrected effectively by the correction member of the illumination optical apparatus, a fine pattern in an arbitrary direction can be transferred onto the photosensitive substrate with high accuracy. can do.

  The microdevice manufacturing method of the present invention includes an exposure step of exposing a predetermined pattern onto a photosensitive substrate using the exposure apparatus of the present invention, and a development step of developing the photosensitive substrate exposed by the exposure step. , Including.

  According to the microdevice manufacturing method of the present invention, a microdevice having a fine pattern in an arbitrary direction can be manufactured satisfactorily.

  According to the illumination optical apparatus of the present invention, the polarization state of the illumination light can be locally corrected effectively by the correction member.

  Further, according to the exposure apparatus of the present invention, the polarization state of the illumination light can be locally corrected effectively by the correction member of the illumination optical apparatus, so that a fine pattern in any direction can be highly accurately formed on the photosensitive substrate. Can be transferred to.

  In addition, according to the microdevice manufacturing method of the present invention, a microdevice having a fine pattern in an arbitrary direction can be manufactured satisfactorily.

  An exposure apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the schematic arrangement of an exposure apparatus according to this embodiment. In the following description, the XYZ orthogonal coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the wafer W, and the Z axis is set in a direction orthogonal to the wafer W. In addition, the illumination optical apparatus according to this embodiment is configured to perform annular illumination.

  As shown in FIG. 1, an exposure apparatus according to this embodiment is an ArF excimer laser that supplies light having a wavelength of about 193 nm, for example, as a laser light source (light source unit) 1 for supplying exposure light (illumination light). A light source or a KrF excimer laser light source that supplies light having a wavelength of about 248 nm is provided. That is, the light source 1 is a narrow-band excimer laser light source for supplying light having a polarization degree of 0.95 or more, and 95% or more of the emitted light beam is linearly polarized light having a vibration direction along one direction.

The degree of polarization V is expressed by the following equation (a). In equation (a), S ₀ is the total intensity, S ₁ is the horizontal linear polarization intensity minus the vertical linear polarization intensity, S ₂ is the 45 degree linear polarization intensity minus the 135 degree linear polarization intensity, and S ₃ is the clockwise circular polarization. Intensity minus left-handed circularly polarized light intensity, respectively. Here, S _{0 to} S ₃ are called Stokes parameters.
V = (S ₁ ² + S ₂ ² + S ₃ ² ) ^1/2 / S ₀ (a)
A substantially parallel light beam emitted from the laser light source 1 along the Z direction has a rectangular cross section extending along the X direction, and is incident on a beam expander 2 including a pair of lenses 2a and 2b. Each lens 2a and 2b has a negative refractive power and a positive refractive power in the YZ plane of FIG. Therefore, the light beam incident on the beam expander 2 is enlarged in the YZ plane of FIG. 1 and shaped into a light beam having a predetermined rectangular cross section.

  The parallel light beam that has passed through the beam expander 2 as the shaping optical system is reflected by the bending mirror 3 and deflected in the Y direction, and then the crystal optical axis is rotatable about the optical axis AX and from the optical axis AX. The light is incident on a quarter-wave plate (polarization adjusting member) 11 configured to be detachable. Here, the quarter-wave plate 11 is a parallel plate formed of quartz, and when elliptically polarized light enters, the crystal optical axis of the quarter-wave plate 11 according to the characteristics of the incident elliptically polarized light. Is set to convert elliptically polarized incident light into linearly polarized light.

  That is, when a KrF excimer laser light source or an ArF excimer laser light source is used as the laser light source 1, the laser light source 1 emits substantially linearly polarized light. Usually, in the optical path between the laser light source 1 and the quarter-wave plate 11, a plurality of right-angle prisms (not shown) are arranged as back reflectors. In general, when linearly polarized light incident on a right-angle prism as a back surface reflecting mirror does not coincide with P-polarized light or S-polarized light with respect to the incident surface of the right-angle prism, the linearly polarized light becomes elliptical due to total reflection at the right-angle prism. Change to polarized light. Therefore, for example, even when incident light changes from linearly polarized light to elliptically polarized light through a right-angle prism, the crystal optical axis of the quarter wavelength plate 11 depends on the characteristics of the elliptically polarized light incident on the quarter wavelength plate 11. Is set, the incident light can be changed from elliptically polarized light to linearly polarized light.

  The light beam that has passed through the quarter-wave plate 11 passes through the half-wave plate (polarization adjusting member) 10 and the depolarizer (non-polarization element) 20. FIG. 2 is a diagram showing a schematic configuration of the half-wave plate 10 and the depolarizer 20. As shown in FIG. 2, the half-wave plate 10 is a parallel plate formed of quartz, and the crystal optical axis is configured to be rotatable about the optical axis AX. The depolarizer 20 includes a wedge-shaped quartz prism 20a and a wedge-shaped quartz prism 20b having a complementary shape to the quartz prism 20a. The quartz prism 20a and the quartz prism 20b are configured to be detachable with respect to the illumination optical path as an integral prism assembly.

  When the crystal optical axis of the half-wave plate 10 is set to make an angle of 0 degree or 90 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the linearly polarized light incident on the half-wave plate 10 Passes through without changing the plane of polarization. In addition, when the crystal optical axis of the half-wave plate 10 is set to form an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the linearly polarized light incident on the half-wave plate 10 is It is converted into linearly polarized light whose polarization plane has changed by 90 degrees. When the crystal optical axis of the quartz prism 20a is set to make an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the linearly polarized light incident on the quartz prism 20a is light in an unpolarized state. Converted to non-polarized light.

  In this embodiment, when the depolarizer 20 is positioned in the illumination optical path, the crystal optical axis of the crystal prism 20a is configured to form an angle of 45 degrees with respect to the plane of polarization of linearly polarized light that is incident. Incidentally, when the crystal optical axis of the crystal prism 20a is set to make an angle of 0 degrees or 90 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the plane of polarization of the linearly polarized light incident on the crystal prism 20a has a polarization plane. Pass through without change. Further, when the crystal optical axis of the half-wave plate 10 is set to make an angle of 22.5 degrees with respect to the plane of polarization of the linearly polarized light that is incident, The light is converted into non-polarized light including a linearly polarized light component that passes through without changing its polarization plane and a linearly polarized light component whose polarization plane changes by 90 degrees.

  In this embodiment, as described above, linearly polarized light is incident on the half-wave plate 10. When the depolarizer 20 is positioned in the illumination optical path, if the crystal optical axis of the half-wave plate 10 is set to make an angle of 0 degrees or 90 degrees with respect to the polarization plane of the linearly polarized light that is incident, the half-wavelength The linearly polarized light incident on the plate 10 passes through the polarization plane without change and enters the quartz prism 20a. Since the crystal optical axis of the crystal prism 20a is set to make an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light that is incident, the linearly polarized light incident on the crystal prism 20a is converted into light that is not polarized. Is done.

  On the other hand, if the crystal optical axis of the half-wave plate 10 is set to make an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the light of the linearly polarized light incident on the half-wave plate 10 is polarized. Becomes linearly polarized light that changes by 90 degrees and enters the crystal prism 20a. Since the crystal optical axis of the quartz prism 20a is set to make an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light that is incident, the linearly polarized light incident on the quartz prism 20a is converted into unpolarized light. Converted. The light depolarized through the quartz prism 20a passes through the quartz prism 20b as a compensator for compensating the traveling direction of the light.

  On the other hand, when the depolarizer 20 is retracted from the illumination optical path, if the crystal optical axis of the half-wave plate 10 is set to make an angle of 0 degrees or 90 degrees with respect to the polarization plane of the linearly polarized light, Linearly polarized light incident on the half-wave plate 10 passes through without changing the plane of polarization. On the other hand, if the crystal optical axis of the half-wave plate 10 is set to make an angle of 45 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the light of the linearly polarized light incident on the half-wave plate 10 is polarized. Becomes linearly polarized light which is changed by 90 degrees.

  As described above, in this embodiment, the depolarizer 20 can be converted into non-polarized light by inserting and positioning the depolarizer 20 in the illumination optical path. In addition, the depolarizer 20 is retracted from the illumination optical path and the crystal optical axis of the half-wave plate 10 is set so as to form an angle of 0 degree or 90 degrees with respect to the polarization plane of the linearly polarized light incident thereon. The light travels without changing the polarization state. Further, the polarization plane is changed by 90 degrees by retracting the depolarizer 20 from the illumination optical path and setting the crystal optical axis of the half-wave plate 10 to be 45 degrees with respect to the polarization plane of the linearly polarized light incident thereon. It can be converted into light in a linearly polarized state.

  That is, the depolarizer 20 is retracted from the illumination optical path and set to have an angle of 0 degree, 90 degrees, or 45 degrees with respect to the polarization plane of the linearly polarized light incident on the crystal optical axis of the half-wave plate 10. Thus, the entire illumination light can be converted into light having a polarization direction in a desired direction, and the polarization state of the entire illumination light can be adjusted.

  The light beam that has passed through the depolarizer 20 enters the diffractive optical element (setting means) 4a. In general, a diffractive optical element (DOE) is formed by forming a step having a pitch of about the wavelength of exposure light (illumination light) on a glass substrate, and has a function of diffracting an incident beam to a desired angle. Specifically, the diffractive optical element 4a has a function of forming an annular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section is incident. Therefore, the light beam passing through the diffractive optical element 4a is a light beam having an annular light intensity distribution, that is, a light beam having an annular cross section in the vicinity of the illumination pupil of the afocal lens 85 (and thus the illumination optical device) to be described later. Form. The diffractive optical element 4a is configured to be retractable from the illumination optical path.

  The light beam that has passed through the diffractive optical element 4 a enters an afocal lens (relay optical system) 85. The afocal lens 85 is set so that the front focal position of the afocal lens 85 and the position of the diffractive optical element 4a substantially coincide with each other, and the rear focal position thereof substantially coincides with the position of the predetermined surface 86 indicated by a broken line in the drawing. System (non-focal optical system). Therefore, the substantially parallel light beam incident on the diffractive optical element 4 a forms an annular light intensity distribution on the illumination pupil plane of the afocal lens 85, and then emerges from the afocal lens 85 as a substantially parallel light beam. .

  In the optical path between the front lens group 85a and the rear lens group 85b of the afocal lens 85, the polarization local correction member 88 and the polarization conversion element (polarization conversion member) are arranged in order from the light source side on or near the illumination pupil. ) 89 and a conical axicon system (setting means) 87 are arranged. The light beam that has been converted into light in the linearly polarized state (or unpolarized state) through the half-wave plate 10 and the depolarizer 20 passes through the front lens group 85a of the afocal lens 85 and reaches the polarization local correction member 88. Incident.

  As shown in FIG. 3, the polarization local correction member 88 is made of fluorite (calcium fluoride) which is a crystal material having a parallel plate shape. Further, a stress applying mechanism (first stress applying means) 50 that applies stress to the polarization local correction member 88 from a predetermined direction (direction perpendicular to the optical axis AX) is provided. The stress applying mechanism 50 is configured to include a pressing mechanism or a pulling mechanism that locally applies stress to the polarization local correction member 88 in a predetermined crystal axis direction. When a predetermined stress is locally applied to a parallel plate formed of fluorite and having a predetermined thickness by the stress applying mechanism 50, a local phase difference is generated in the parallel plate formed of fluorite. The parallel plate formed of fluorite functions as a correction member that locally corrects the polarization state of the illumination light. 3 indicates the stress applied from the stress applying mechanism 50 to the polarization local correction member 88, and the length of the arrow indicates the magnitude of the stress.

FIG. 4 is a diagram for explaining the crystal axis of fluorite. As shown in FIG. 4, the crystal axis of fluorite is defined based on a cubic crystal axis a ₁ a ₂ a ₃ (indicated by thin line arrows in the figure). That is, the crystal axes along the crystal axis + _{a 1} [100], the crystal axes along the crystal axis + _{a 2} [010], the crystal axes along the crystal axis + _{a 3} [001] are defined respectively (in FIG thick arrow ). Further, the crystal axis [101] that forms 45 degrees with the crystal axis [100] and the crystal axis [001] in the a ₁ a ₃ plane, and 45 degrees with the crystal axis [100] and the crystal axis [010] in the a ₁ a ₂ plane. The crystal axis [110] is defined in the direction that forms the crystal axis [011], and the crystal axis [011] is defined in the direction that forms 45 degrees with the crystal axis [010] and the crystal axis [001] in the a ₂ a ₃ plane. Show). Further, the crystal axis [111] is defined in the + direction of the crystal axes a ₁ a ₂ a _{3 and in} the direction that forms the same angle as the crystal axis [100], the crystal axis [010], and the crystal axis [001] ( (Indicated by bold arrows in the figure). In FIG. 3, only the crystal axes in the space defined by the crystal axis + a ₁ , the crystal axis + a ₂ , and the crystal axis + a ₃ are illustrated, but the crystal axes are similarly defined in other spaces.

  The stress applying mechanism 50 described above has the crystal axis [100], crystal axis [010], crystal axis [001], crystal axis among the crystal axes defined in FIG. Stress is applied in any one of [110], crystal axis [101], and crystal axis [011]. By applying stress in the crystal axis direction, a phase difference can be effectively generated in the polarization local correction member 88, and the polarization state of the illumination light can be locally corrected.

  The illumination light that has passed through the polarization local correction member 88 enters the polarization conversion element 89. FIG. 5 is a diagram schematically showing the configuration of the polarization conversion element 89. FIG. 6 is a diagram schematically showing a ring-shaped light beam cross section set in the circumferential polarization state (S polarization state) by the action of the polarization conversion element. In this embodiment, the polarization conversion element 89 is disposed immediately before the conical axicon system 87, that is, at or near the pupil of the illumination optical device. Therefore, in the case of annular illumination, a light beam having a substantially annular cross section centered on the optical axis AX is incident on the polarization conversion element 89.

  Referring to FIG. 5, the polarization conversion element 89 has a ring-shaped effective region centered on the optical axis AX as a whole, and this ring-shaped effective region is applied in the circumferential direction centered on the optical axis AX. It consists of eight divided fan-shaped basic elements. In these eight basic elements, a pair of basic elements facing each other across the optical axis AX have the same characteristics. That is, the eight basic elements each include two basic elements 89A to 89D having different thicknesses (thicknesses in the optical axis direction) along the light transmission direction (Y direction).

  Specifically, the thickness of the first basic element 89A is the largest, the thickness of the fourth basic element 89D is the smallest, and the thickness of the second basic element 89B is set larger than the thickness of the third basic element 89C. ing. As a result, one surface (for example, the incident surface) of the polarization conversion element 89 is planar, but the other surface (for example, the exit surface) is uneven due to the difference in thickness of each basic element. In addition, both surfaces (incident surface and exit surface) of the polarization conversion element 89 can be formed in an uneven shape.

  In this embodiment, each of the basic elements 89A to 89D is made of crystal as a crystal material that is a light-transmitting optical material, and the crystal optical axis of each of the basic elements 89A to 89D is substantially coincident with the optical axis AX. That is, it is set so as to substantially coincide with the traveling direction of the incident light.

  In this embodiment, when linearly polarized light having a polarization direction in the Z direction is incident, the first basic element 89A changes the polarization direction in the direction obtained by rotating the Z direction by +180 degrees around the Y axis, that is, in the Z direction. The thickness is set so as to emit linearly polarized light. Accordingly, in this case, the polarization direction of the light beam in the pair of arcuate regions 31A formed by the light beam subjected to the optical rotation of the pair of first basic elements 89A in the ring-shaped light beam cross section 31 shown in FIG. become.

  When linearly polarized light having a polarization direction in the Z direction is incident, the second basic element 89B rotates the Z direction by +135 degrees around the Y axis, that is, rotates the Z direction by −45 degrees around the Y axis. The thickness is set so as to emit linearly polarized light having a polarization direction in a predetermined direction. Therefore, in this case, the polarization direction of the light beam in the pair of arc-shaped regions 31B formed by the light beam subjected to the optical rotation of the pair of second basic elements 89B in the ring-shaped light beam cross section 31 shown in FIG. Is rotated by -45 degrees around the Y axis.

  When the linearly polarized light having the polarization direction in the Z direction is incident, the third basic element 89C emits the linearly polarized light having the polarization in the direction rotated by +90 degrees around the Y axis, that is, in the X direction. The thickness is set to be. Accordingly, in this case, the polarization direction of the light beam in the pair of arcuate regions 31C formed by the light beam subjected to the optical rotation of the pair of third basic elements 89C in the ring-shaped light beam cross section 31 shown in FIG. become.

  The fourth basic element 89D has a thickness so that when linearly polarized light having a polarization direction in the Z direction is incident, the linearly polarized light having polarization in a direction rotated by +45 degrees around the Y axis is emitted. Is set. Accordingly, in this case, the polarization direction of the light beam in the pair of arcuate regions 31D formed by the light beam subjected to the optical rotation of the pair of fourth basic elements 89D in the ring-shaped light beam cross section 31 shown in FIG. Is rotated by +45 degrees around the Y axis.

  It should be noted that the polarization conversion element 89 has a size that is not less than 3/10 of the radial size of the effective area of the polarization conversion element 89 so that normal circular illumination can be performed without retracting the polarization conversion element 89 from the optical path. A circular central region 89E having no property is provided. Here, the central region 89E may be formed of an optical material that does not have optical activity, such as quartz, or may be a circular opening.

  In this embodiment, linearly polarized light having a polarization direction in the Z direction is incident on the polarization conversion element 89. As a result, as shown in FIG. 6, the light emitted from the polarization conversion element 89 is centered on the optical axis AX at the center position along the circumferential direction of each of the arc-shaped regions 31A to 31D. A linear polarization state (S polarization state) having a polarization direction substantially coinciding with the tangential direction of the circle is obtained.

  The illumination light that has passed through the polarization conversion element 89 enters the conical axicon system 87. FIG. 7 is a diagram showing a schematic configuration of the conical axicon system 87 arranged in the vicinity of the illumination pupil of the illumination optical apparatus or in the vicinity of the illumination pupil. The conical axicon system 87 is arranged in order from the light source side to the first prism 87a having a concave conical refractive surface (concave refractive surface) with respect to the optical axis AX direction and the concave conical refractive surface of the first prism 87a. A second prism 87b having a convex conical refracting surface (convex refracting surface) formed so as to be in contact with each other is provided. The first prism 87a is arranged with the flat surface facing the light source and the concave conical refracting surface facing the mask M, and the second prism 87b has the convex conical refracting surface facing the optical axis AX and the mask. It is arranged with a flat surface on the M side.

  Further, at least one of the first prism 87a and the second prism 87b is configured to be movable along the optical axis AX, and the concave conical refracting surface of the first prism 87a and the convex conical shape of the second prism 87b. The distance from the refracting surface is variable. Here, in a state where the concave conical refracting surface of the first prism 87a and the convex conical refracting surface of the second prism 87b are in contact with each other, the conical axicon system 87 functions as a parallel flat plate, which will be described later. There is no effect on the annular secondary light source formed through the microlens array 8. However, when the concave conical refracting surface of the first prism 87a and the convex conical refracting surface of the second prism 87b are separated from each other, the conical axicon system 87 functions as a so-called beam expander. Therefore, the incident angle of the incident light beam on the predetermined surface 86 indicated by a broken line in FIG. 1 changes with the change in the interval of the conical axicon system 87.

  FIG. 8 is a diagram for explaining the operation of the conical axicon system 87 with respect to the secondary light source formed in the annular illumination. The smallest ring-shaped secondary light source 130a formed in a state where the distance between the conical axicon systems 87 is 0 and the focal length of a zoom lens 90 described later is set to a minimum value (hereinafter referred to as “standard state”) By increasing the interval of the conical axicon system 87 from 0 to a predetermined value, the width (1/2 of the difference between the outer diameter and the inner diameter: indicated by an arrow in the figure) does not change, and the outer diameter and the inner diameter are changed. Are changed to an annular secondary light source 130b. That is, due to the action of the conical axicon system 87, the width of the annular light source does not change, and the annular ratio (inner diameter / outer diameter) and size (outer diameter) both change.

  The light beam that has passed through the afocal lens 85 is incident on a microlens array (optical integrator) 8 through a zoom lens (setting means) 90 for variable σ value. The position of the predetermined surface 86 is disposed at or near the front focal position of the zoom lens 90, and the incident surface of the microlens array 8 is disposed at or near the rear focal plane of the zoom lens 90. That is, in the zoom lens 90, the predetermined surface 86 and the incident surface of the microlens array 8 are arranged in a substantially Fourier relationship, and as a result, the illumination pupil surface of the afocal lens 85 and the incident surface of the microlens array 8 are arranged. Optically arranged in a conjugate manner. Accordingly, on the incident surface of the microlens array 8, for example, an annular illumination field with the optical axis AX as the center is formed in the same manner as the illumination pupil plane of the afocal lens 85. The overall shape of the annular illumination field changes in a similar manner depending on the focal length of the zoom lens 90. That is, the size of the secondary light source (surface light source) formed at a position conjugate with the illumination pupil position by the microlens array 8 is adjusted while the light energy of the illumination light emitted from the laser light source 1 is kept substantially constant. It can be changed in a similar manner depending on the focal length of the lens 90.

  FIG. 9 is a diagram for explaining the action of the zoom lens 90 on the secondary light source formed in the annular illumination. The ring-shaped secondary light source 130a formed in the standard state increases the focal length of the zoom lens 90 from the minimum value to a predetermined value, thereby maintaining the light energy of the illumination light substantially constant and having an overall shape. It changes into the ring-shaped secondary light source 130c expanded similarly. That is, due to the action of the zoom lens 90, both the width and size (outer diameter) change without changing the annular ratio of the annular secondary light source.

  The light beam that has passed through the zoom lens 90 enters the microlens array 8. The incident angle of the incident light beam on the microlens array 8 changes in the same manner as the angle of the incident light beam on the predetermined surface 86 changes with the change in the interval of the conical axicon system 87.

  The microlens array 8 is an optical element composed of microlenses made of quartz having a large number of positive refractive powers arranged vertically and horizontally and densely. Each microlens constituting the microlens array 8 has a rectangular cross section similar to the shape of the illumination field to be formed on the mask M (and thus the shape of the exposure region to be formed on the wafer W). The light beam incident on the microlens array 8 is two-dimensionally divided by a large number of microlenses, and is substantially the same as the illumination field formed by the light beam incident on the microlens array 8 on the rear focal plane (and thus the illumination pupil). A secondary light source having a light intensity distribution, that is, a secondary light source composed of a substantial surface light source having an annular shape centering on the optical axis AX is formed. An aperture stop provided so that the light flux from the annular secondary light source formed on the rear focal plane of the microlens array 8 can be arranged on the rear focal plane (exit plane) of the microlens array 8 or in the vicinity thereof. 12 is passed. The aperture stop 12 restricts the size of a secondary light source (surface light source formed at the illumination pupil position of the illumination optical device) formed on the rear focal plane of the microlens array 8 to a predetermined size, for example, an iris stop. Etc. The light flux that has passed through the aperture stop 12 illuminates the mask blind MB in a superimposed manner via the condenser lens 9a.

  In the mask blind MB as an illumination field stop, a rectangular illumination field corresponding to the shape and focal length of each microlens constituting the microlens array 8 is formed. The light flux that has passed through the rectangular opening (light transmitting portion) of the mask blind MB is subjected to the light condensing action of the imaging optical system 9b made of quartz, and then the mask (irradiated) on which a predetermined pattern is formed. Surface) M is illuminated in a superimposed manner. That is, the imaging optical system 9b forms an image of the rectangular opening of the mask blind MB on the mask M. The light beam that has passed through the pattern of the mask M forms a pattern image of the mask M on the wafer W, which is a photosensitive substrate, via the projection optical system PL.

  Here, the mask M is held on a mask stage MS, and the wafer W as a photosensitive substrate is held on a wafer stage WS as a substrate stage. In this way, the pattern image of the mask M is scanned and exposed to the photosensitive area of the wafer W while moving the mask stage MS and the wafer stage WS along the scanning direction in a plane orthogonal to the optical axis AX of the projection optical system PL. Is done. The movement of the mask stage MS and the wafer stage WS to scan and expose the pattern image of the mask M onto the photosensitive region of the wafer W, and the next operation to move the wafer stage WS to expose the exposed region of the wafer W ( The pattern of the mask M is sequentially exposed in each exposure region of the wafer W by a so-called step-and-scan method in which the step operation is repeated. In order to perform the exposure operation for forming an image of the pattern of the mask M in the exposure area of the wafer W and the exposure in the exposure area of the next wafer W while mainly controlling the two-dimensional operation of the wafer stage WS. The pattern of the mask M may be sequentially exposed on each exposure region of the wafer W by a so-called step-and-repeat method in which control (step operation) for moving the wafer stage WS is repeated.

  The exposure apparatus according to this embodiment includes a polarization state measuring device 6 for measuring the polarization state of illumination light with respect to the wafer W. The polarization state measuring device 6 is provided at one end of the wafer stage WS, and the polarization state measuring device 6 and the stress applying mechanism 50 are electrically connected to the control device 30, respectively. In addition, although mentioned later, based on the measurement result of the polarization state measuring apparatus 6, the control part 30 gives local stress etc. with respect to a correction | amendment optical member via the stress provision mechanism 50 grade | etc., And deteriorates locally. Correct the polarization state.

  FIG. 10 is a diagram showing a schematic light property of the polarization state measuring device 6. The polarization state measuring device 6 includes a pinhole member 60 that can be positioned at or near the position of the wafer W. When the polarization state measuring device 6 is used, the wafer W is retracted from the optical path. The light that has passed through the pinhole 60 a of the pinhole member 60 becomes a substantially parallel light beam through the collimator lens 61, is reflected by the reflecting mirror 62, and then enters the relay lens system 63. The substantially parallel light flux via the relay lens system 63 reaches the detection surface 66a of the two-dimensional CCD 66 after passing through the λ / 4 plate 64 as a phase shifter and the polarization beam splitter 65 as a polarizer.

  Here, the λ / 4 plate 64 is configured to be rotatable about the optical axis, and the λ / 4 plate 64 has a setting unit 67 for setting a rotation angle about the optical axis. It is connected. Thus, when the polarization degree of the illumination light with respect to the wafer W is not 0, the light intensity distribution on the detection surface 66a of the two-dimensional CCD 66 is changed by rotating the λ / 4 plate 64 around the optical axis via the setting unit 67. To do. Therefore, in the polarization state measuring device 6, the setting unit 67 is used to detect the change in the light intensity distribution on the detection surface 66a while rotating the λ / 4 plate 64 around the optical axis, and the rotational phase shift method is used from the detection result. Thus, the polarization state of the illumination light can be measured.

  The rotational phase shifter method is described in detail in, for example, Tsuruta, “Pencil of Light-Applied Optics for Optical Engineers”, New Technology Communications Inc. Actually, the polarization state of the illumination light at a plurality of positions in the wafer surface is measured while the pinhole member 60 (and thus the pinhole 60a) is moved two-dimensionally along the wafer surface. At this time, since the polarization state measuring device 6 detects a change in the light intensity distribution on the two-dimensional detection surface 66a, the polarization state distribution in the pupil of the illumination light can be measured based on the detection distribution information. it can.

  By the way, in the polarization state measuring apparatus 6, it is also possible to use a λ / 2 plate instead of the λ / 4 plate 64 as a phase shifter. Whatever phase shifter is used, in order to measure the polarization state, that is, the four Stokes parameters, the relative angle around the optical axis between the phase shifter and the polarizer (polarization beam splitter 65) is changed. It is necessary to detect a change in the light intensity distribution on the detection surface 66a in at least four different states by retracting the phase shifter or polarizer from the optical path. In this embodiment, the λ / 4 plate 64 as a phase shifter is rotated around the optical axis. However, the polarization beam splitter 65 as a polarizer may be rotated around the optical axis. Both of the polarizers may be rotated around the optical axis. Further, instead of or in addition to this operation, one or both of the λ / 4 plate 64 serving as a phase shifter and the polarization beam splitter 65 serving as a polarizer may be inserted into and removed from the optical path.

  A measurement result by the polarization state measuring device 6 is output to the control unit 30. The control unit 30 determines whether or not the illumination light has an appropriate polarization state, and in order to change the polarization state of the illumination light with respect to the wafer W (and thus the illumination light with respect to the mask M) to a desired polarization state, the stress applying mechanism. 50 outputs a control signal. Therefore, the polarization state of the illumination light can be locally corrected, and the mask M can be illuminated with light having a desired polarization state, and good exposure can be performed under appropriate illumination conditions. Therefore, the illumination light on the wafer can be in an accurate circumferential polarization state (S change state), and a fine pattern in an arbitrary direction can be exposed on the photosensitive substrate with high accuracy.

  In the above-described embodiment, the parallel plate-shaped polarization local correction member 88 is used. However, as shown in FIG. 11, it is formed of fluorite (calcium fluoride), which is a crystal material having a disk shape. By applying local stress to the member from a predetermined direction, the member may function as a correction member that locally corrects the polarization state. In FIG. 11, the arrow indicates the stress applied to the polarization local correction member, and the length indicates the magnitude of the stress. In this case, the stress is applied locally from the direction perpendicular to the optical axis AX by the stress applying mechanism. The stress is applied in the crystal axis [100], crystal axis [010], crystal axis [001], crystal axis [110], crystal axis [101] among the crystal axes defined in FIG. , It is made to coincide with any one of the crystal axes [011]. By applying stress in the crystal axis direction, a phase difference can be effectively generated in the polarization local correction member, and the polarization state of the illumination light can be locally corrected.

  Further, local stress may be applied to the polarization local correction member from the optical axis direction. That is, as shown in FIG. 12, by applying a stress to a predetermined position in the optical axis direction on a parallel plate formed of fluorite, it may function as a correction member that locally corrects the polarization state. Good. In FIG. 12, the arrow indicates the stress applied to the polarization local correction member, and the length indicates the magnitude of the stress. By making the direction in which this stress is applied coincide with the direction described with reference to FIG. 11, a phase difference can be effectively generated in the polarization local correction member, and the polarization state of the illumination light is corrected locally. Can do.

  In the above-described embodiment, the polarization local correction member 88 is disposed adjacent to the light source side of the polarization conversion element 89. However, if the polarization local correction member 88 is disposed at or near the position of the pupil formed in the illumination optical device. For example, the microlens array 8 may be disposed adjacent to the light source side.

  In the above-described embodiment, the polarization local correction member 88 is used to locally correct the polarization state of the illumination light. However, as shown in FIG. A stress applying mechanism (second stress applying means) 51 to be applied is provided, and a local stress is applied to the polarization conversion element 89, whereby the polarization state of the illumination light is also locally corrected in the polarization conversion element 89. A function may be provided, and the polarization state of the illumination light may be locally corrected by the polarization local correction member 88 and the polarization conversion element 89. In this case, as shown in FIG. 14, the stress applying mechanisms 50 and 51, based on the control signal based on the measurement result of the polarization state measuring device 6 output from the control unit 30, A stress is locally applied to the conversion element 89. In FIG. 14, the arrows indicate stress applied to the polarization local correction member 88 and the polarization conversion element 89, and the length indicates the magnitude of the stress.

  Further, when a function for locally correcting the polarization state of the illumination light is provided to the polarization conversion element 89 by applying a local stress to the polarization conversion element 89, the polarization local correction member 88 is provided. Alternatively, the polarization state of the illumination light may be locally corrected only by the polarization conversion element 89. In this case, the polarization conversion element 89 functions as a correction member that locally corrects the polarization state of the illumination light and an element that converts the polarization state of the illumination light.

  In the exposure apparatus according to the above-described embodiment, the quarter-wave plate 11 and the half-wave plate 10 are formed of quartz, but fluorite (fluoride fluoride) which is a crystal material having a parallel plate shape. (Calcium) may be made to function as a quarter-wave plate and a half-wave plate by applying a uniform stress from a direction perpendicular to the optical axis AX. In this case, as shown in FIG. 15, a stress applying mechanism 52 for applying stress from a direction perpendicular to the optical axis AX is provided on the parallel plate 100 functioning as a quarter wavelength plate. Further, a stress applying mechanism 53 that applies stress from a direction perpendicular to the optical axis AX is provided on the parallel plate 101 functioning as a half-wave plate. The stress applying mechanisms 52 and 53 apply stress in a predetermined crystal axis direction to the parallel plate 100 functioning as a quarter wavelength plate and the parallel plate 101 functioning as a half wavelength plate.

  It should be noted that the stress applying mechanisms 52 and 53 have a crystal axis defined in FIG. 4 described above with respect to the parallel plate 100 that functions as a quarter-wave plate and the parallel plate 101 that functions as a half-wave plate. Uniform stress in any one of the crystal axis [100], the crystal axis [010], the crystal axis [001], the crystal axis [110], the crystal axis [101], and the crystal axis [011]. Give. That is, as shown in FIG. 16, plate-like members 54 are arranged above and below the parallel flat plate, and stress is applied through the plate-like members 54. In FIG. 16, the arrows indicate the stress applied to the parallel plates 100 and 101, and the length indicates the magnitude of the stress. Further, the direction of applying the stress is not limited to the two upper and lower directions, and may be the two left and right directions, or may be the four upper and lower and left and right directions. By applying stress in the crystal axis direction, a uniform phase difference is generated in the entire parallel plate 100 and parallel plate 101 and functions as a quarter-wave plate and a half-wave plate.

  In the above-described embodiment, the fluorite that is a crystal material having a disc shape that functions as a quarter-wave plate and the fluorite that is a crystal material having a disc shape that functions as a half-wave plate are used. A uniform stress may be applied from a direction perpendicular to the optical axis AX. In this case, as shown in FIG. 17, a plate-like member is disposed on the circumferential portion of a member having a disk shape, and stress is applied through this member. As a result, a uniform phase difference is generated in the entire disk, and it functions as a quarter-wave plate or a half-wave plate.

  Here, when the parallel plate (or disc) 101 functioning as a half-wave plate is disposed in the optical path of the illumination optical device instead of the half-wave plate 10 in the above-described embodiment, the parallel plate is formed as a parallel plate. The parallel plate 101 is arranged so that the fast axis generated in the parallel plate by applying the stress is directed in a predetermined direction. That is, when the fast axis generated on the parallel plate 101 is set to make an angle of 0 degree or 90 degrees with respect to the plane of polarization of the linearly polarized light incident thereon, the linearly polarized light incident on the parallel plate 101 is polarized. The plane passes without changing. Further, when the fast axis generated in the parallel plate 101 is set to form an angle of 45 degrees with respect to the polarization plane of the linearly polarized light incident thereon, the polarization plane of the linearly polarized light incident on the parallel plate 101 has a polarization plane of 90. It is converted into linearly polarized light that has changed by a certain degree.

  In the above-described embodiment, the changed local correction member may be formed of any one of magnesium fluoride, barium fluoride, strontium fluoride, and calcite, and the polarization conversion element may be calcium fluoride, magnesium fluoride. , Barium fluoride, strontium fluoride, and calcite.

  In the exposure apparatus according to the above-described embodiment, the illumination optical device illuminates the mask (reticle) M (illumination process), and the transfer pattern formed on the mask M using the projection optical system PL is transferred to the photosensitive substrate ( By transferring the wafer (wafer) W (transfer process), a microdevice (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. FIG. 18 shows an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer W as a photosensitive substrate using the exposure apparatus according to the above-described embodiment. This will be described with reference to a flowchart.

  First, in step S301 of FIG. 18, a metal film is deposited on one lot of wafers W. In the next step S302, a photoresist is applied on the metal film on the wafer W of the l lot. Thereafter, in step S303, using the exposure apparatus according to the above-described embodiment, the image of the pattern on the mask M is sequentially exposed to each shot region on the wafer W of the one lot via the projection optical system PL. Transcribed. After that, in step S304, the photoresist on the one lot of wafers W is developed, and in step S305, etching is performed on the one lot of wafers W using the resist pattern as a mask M. A circuit pattern corresponding to the upper pattern is formed in each shot area on each wafer W.

  Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, since the exposure apparatus according to the above-described embodiment is used, a fine pattern can be satisfactorily exposed on the wafer. In steps S301 to S305, a metal is deposited on the wafer W, a resist is applied onto the metal film, and exposure, development, and etching processes are performed. Prior to these processes, the wafer is processed. It goes without saying that after a silicon oxide film is formed on W, a resist is applied onto the silicon oxide film, and each step such as exposure, development, and etching may be performed.

  In the exposure apparatus according to the above-described embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 19, in the pattern forming step S401, a so-called photolithographic step of transferring and exposing the pattern of the mask M onto a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus according to the second embodiment described above. Is executed. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step S402.

  Next, in the color filter forming step S402, a large number of groups of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter formation step S402, a cell assembly step S403 is executed. In the cell assembly step S403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step S401, the color filter obtained in the color filter formation step S402, and the like. In the cell assembly step S403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step S401 and the color filter obtained in the color filter formation step S402, and a liquid crystal panel (liquid crystal cell ).

  Thereafter, in a module assembly step S404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the method for manufacturing a liquid crystal display element described above, since the exposure apparatus according to the above-described embodiment is used, a fine pattern can be satisfactorily exposed on the wafer.

It is a figure which shows schematic structure of the exposure apparatus concerning Embodiment. It is a figure which shows schematic structure of the 1/2 wavelength plate and depolarizer with which the illumination optical apparatus concerning embodiment is provided. It is a figure for demonstrating the polarization | polarized-light local correction member concerning embodiment. It is a figure for demonstrating the crystal axis of a fluorite. It is a figure which shows the structure of the polarization conversion element concerning embodiment. It is a figure for demonstrating the cross section of the light beam converted into the circumferential direction polarization | polarized-light state by the polarization conversion element concerning embodiment. It is a figure which shows schematic structure of the cone axicon system with which the illumination optical apparatus concerning embodiment is provided. It is a figure for demonstrating the effect | action of the cone axicon system with respect to the secondary light source formed in the annular illumination concerning embodiment. It is a figure for demonstrating the effect | action of the zoom lens with respect to the secondary light source formed in the annular illumination concerning embodiment. It is a figure which shows schematic structure of the polarization state measuring apparatus concerning embodiment. It is a figure which shows the other example of a polarization local correction member. It is a figure which shows the other example of a polarization local correction member. It is a figure which shows the structure at the time of giving the function as a polarization | polarized-light local correction member to a polarization conversion element. It is a figure which shows the polarization conversion element at the time of giving the function as a polarization | polarized-light local correction member. It is a figure which shows the other structure of a quarter wavelength plate and a half wavelength plate. It is a figure which shows the other structure of a quarter wavelength plate and a half wavelength plate. It is a figure which shows the other structure of a quarter wavelength plate and a half wavelength plate. It is a flowchart which shows the method of manufacturing the semiconductor device as a microdevice concerning embodiment. It is a flowchart which shows the method of manufacturing the liquid crystal display element as a micro device concerning embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser light source, 2 ... Beam expander, 3 ... Bending mirror, 4a ... Diffraction optical element, 6 ... Polarization state measuring apparatus, 8 ... Micro lens array, 9a ... Condenser lens, 9b ... Imaging optical system, 10 ... 1 / 2 wavelength plate, 11 ... 1/4 wavelength plate, 12 ... aperture stop, 20 ... depolarizer, 30 ... control unit, 85 ... afocal lens, 87 ... conical axicon system, 87a ... first prism, 87b ... second prism , 88 ... polarization local correction member, 89 ... polarization conversion element, 90 ... zoom lens, MB ... mask blind, M ... mask, PL ... projection optical system, W ... wafer.

Claims (11)

In an illumination optical device that illuminates the illuminated surface with illumination light emitted from a light source,
A correction member that locally corrects the polarization state of the illumination light by applying a predetermined stress;
The illumination optical apparatus, wherein the correction member is disposed at or near a position where an illumination pupil is formed in an optical path from the light source to the irradiated surface.   The illumination optical apparatus according to claim 1, further comprising a polarization adjustment member that adjusts a polarization state of the entire illumination light emitted from the light source in an optical path between the light source and the correction member.   3. The illumination according to claim 1, further comprising setting means for setting a light intensity distribution having a desired shape at the illumination pupil in an optical path between the polarization adjusting member and the irradiated surface. Optical device.   The illumination optical apparatus according to any one of claims 1 to 3, further comprising first stress applying means for applying a desired stress to the correction member. In order to illuminate the illuminated surface in a desired polarization state, a polarization conversion member that imparts a desired polarization action to the illumination light in the optical path from the light source to the illuminated surface,
The illumination optical device according to any one of claims 1 to 4, wherein the correction member is disposed adjacent to the polarization conversion member.   2. The apparatus according to claim 1, further comprising: a measuring unit that measures a polarization state on the irradiated surface; and a control unit that controls the first stress applying unit based on a measurement result from the measuring unit. Item 6. The illumination optical apparatus according to any one of Items 5.   The illumination optical apparatus according to any one of claims 1 to 6, further comprising second stress applying means for applying a desired stress to the polarization conversion member.   8. The illumination optical apparatus according to claim 7, wherein the second stress applying unit is controlled by the control unit based on a measurement result from the measurement unit.   The at least one of the correction member and the polarization conversion member is formed of any one of calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride, and calcite. The illumination optical device according to any one of claims 1 to 8. In an exposure apparatus that exposes a predetermined pattern illuminated by illumination light emitted from a light source onto a photosensitive substrate via a projection optical system,
An exposure apparatus comprising the illumination optical apparatus according to any one of claims 1 to 9. An exposure step of exposing a predetermined pattern on the photosensitive substrate using the exposure apparatus according to claim 10;
A developing step of developing the photosensitive substrate exposed by the exposing step;
A method for manufacturing a microdevice, comprising:

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