WO2013039240A1 - 照明光学装置、光学系ユニット、照明方法、並びに露光方法及び装置 - Google Patents
照明光学装置、光学系ユニット、照明方法、並びに露光方法及び装置 Download PDFInfo
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- WO2013039240A1 WO2013039240A1 PCT/JP2012/073745 JP2012073745W WO2013039240A1 WO 2013039240 A1 WO2013039240 A1 WO 2013039240A1 JP 2012073745 W JP2012073745 W JP 2012073745W WO 2013039240 A1 WO2013039240 A1 WO 2013039240A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
- H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
- H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
- H01L21/0274—Photolithographic processes
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70058—Mask illumination systems
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70058—Mask illumination systems
- G03F7/70091—Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
- G03F7/70108—Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/06—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the phase of light
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0927—Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
- G03F7/70566—Polarisation control
Definitions
- the present invention relates to an illumination technique for illuminating an irradiated surface with light supplied from a light source, an optical technique for changing the polarization state of light supplied from the light source, an exposure technique using the illumination technique or optical technique, and the exposure technique.
- the present invention relates to a device manufacturing technique using the.
- an exposure apparatus such as a stepper or a scanning stepper used in a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor element illuminates a reticle (mask) under various illumination conditions and with a uniform illuminance distribution.
- an illumination optical device is provided.
- the light intensity distribution on the pupil plane of the illumination optical system is set to a distribution in which the intensity increases in a circular area, an annular area, a multipolar area, or the like according to the illumination conditions.
- an intensity distribution setting optical system having a plurality of replaceable diffractive optical elements (diffractive optical elements) or a movable multi-mirror spatial light modulator having a large number of minute mirror elements with variable tilt angles I was prepared.
- a plurality of light beams are each divided into two light beams (ordinary rays and extraordinary rays) whose polarization directions are orthogonal with a birefringent crystal, and the two divided light beams are individually reflected. Then, by illuminating a predetermined area on the pupil plane of the illumination optical system, an illumination optical device that can set the polarization direction of light at each part on the pupil plane to one of the orthogonal polarization directions is proposed. (For example, refer to Patent Document 1).
- the conventional illumination optical device splits a plurality of light beams through a birefringent crystal and splits them into two light beams whose polarization directions are orthogonal to each other, and individually reflects the two divided light beams.
- the possible polarization directions were limited to any of the orthogonal polarization directions.
- various applications including linearly polarized light of at least four different polarization directions are used in applications where the distribution of the polarization direction in the annular light intensity distribution is set substantially in the circumferential direction or the radial direction during annular illumination, for example. It is preferable to generate a uniform polarization state distribution.
- the conventional illumination optical apparatus cannot set such a polarization state distribution.
- an object of the present invention is to illuminate an irradiated surface with light having various polarization state distributions.
- an illumination optical device that illuminates an illuminated surface with light supplied from a light source.
- This illumination optical device is arranged in a separation optical system that separates a first light flux and a second light flux having different polarization states from light supplied from the light source, and at least one optical path of the first light flux and the second light flux.
- a variable optical system that changes a phase difference distribution between the first light flux and the second light flux, and a combining optical system that combines the first light flux and the second light flux whose phase difference distribution is changed.
- an illumination optical device that illuminates an irradiated surface with light supplied from a light source.
- This illumination optical device is arranged in a separation optical system that separates a first light flux and a second light flux having different polarization states from light supplied from the light source, and at least one optical path of the first light flux and the second light flux.
- variable optical system that changes a phase difference distribution between the first light beam and the second light beam
- a combining optical system that combines the first light beam and the second light beam whose phase difference distribution is changed, and a combination thereof
- a polarization state variable element that is disposed in an optical path of a light beam synthesized by the optical system and changes a polarization state of the synthesized light beam.
- the illumination optical apparatus in the exposure apparatus that illuminates the pattern with the exposure light and exposes the substrate with the exposure light through the pattern and the projection optical system.
- An exposure apparatus that uses light from the illumination optical apparatus as the exposure light is provided.
- the optical system unit which changes the polarization state of the light supplied from a light source is provided.
- the optical system unit is arranged in a separation optical system that separates a first light beam and a second light beam having different polarization states from light supplied from the light source, and at least one optical path of the first light beam and the second light beam.
- variable optical system that changes a phase difference distribution between the first light beam and the second light beam
- a combining optical system that combines the first light beam and the second light beam whose phase difference distribution is changed, and a combination thereof
- a polarization state variable element that is disposed in an optical path of a light beam synthesized by the optical system and changes a polarization state of the synthesized light beam.
- the illumination method which illuminates a to-be-irradiated surface with the light supplied from a light source.
- This illumination method separates the first light flux and the second light flux having different polarization states from the light supplied from the light source, and gives a variable phase difference distribution between the first light flux and the second light flux. And synthesizing the first light flux and the second light flux provided with a variable phase difference distribution.
- an illumination method for illuminating the irradiated surface with light supplied from a light source.
- the illumination method includes separating a first light beam and a second light beam having different polarization states from light supplied from the light source, changing a phase difference distribution between the first light beam and the second light beam, Combining the first light beam and the second light beam whose phase difference distribution has been changed, and passing the light beam synthesized by the synthesis optical system through a polarization state variable element.
- the exposure method which illuminates a pattern with exposure light and exposes a board
- This exposure method uses the light directed to the irradiated surface as the exposure light using the illumination method of the aspect of the present invention.
- the first light flux and the second light flux which are provided with the phase difference distribution and have different polarization states, are combined.
- the combined two light fluxes have various variable polarization state distributions according to the phase difference distribution. Therefore, the irradiated surface can be illuminated with light having various distributions of polarization states by using the combined two light beams.
- the optical system unit of the fourth aspect, or the illumination method of the sixth aspect of the present invention two light fluxes having different polarization states and having a phase difference distribution are provided. It is synthesized and passes through the polarization state variable element. Thereby, for example, a variable polarization distribution having various polarization directions can be obtained according to the phase difference distribution. Therefore, the irradiated surface can be illuminated with light having various polarization state distributions by using the light that has passed through the polarization state variable element.
- FIG. 1 It is a figure which shows schematic structure of the exposure apparatus of an example of embodiment.
- A is a view showing an optical system including the polarization unit 15 in FIG. 1
- B is a view showing a polarization direction of incident illumination light
- C) and (D) are a first light flux and a second light flux, respectively.
- A) is a figure which shows the light intensity distribution of annular illumination
- (B) and (C) are figures which show the example of distribution of the polarization state at the time of annular illumination, respectively.
- A) is a figure which shows the light intensity distribution of normal illumination
- B) and (C) are figures which show the example of distribution of the polarization state at the time of normal illumination, respectively.
- (A) is a figure which shows the light intensity distribution of 4 pole illumination
- (B) and (C) are figures which show the example of the distribution of the polarization state at the time of 4 pole illumination, respectively.
- (A) is a figure which shows the polarization unit of a 4th modification
- (B) is an expansion perspective view which shows a part of variable polarizing element in FIG. 10 (A).
- FIG. 12 It is a figure which shows the polarization unit of a 5th modification.
- A is a figure which shows the principal part of the illuminating device of the other example of embodiment
- B is an enlarged view which shows the polarizing unit in FIG. 12 (A).
- FIG. 1 shows a schematic configuration of an exposure apparatus EX according to the present embodiment.
- the exposure apparatus EX is, for example, a scanning exposure type exposure apparatus (projection exposure apparatus) composed of a scanning stepper (scanner).
- the exposure apparatus EX includes an illumination apparatus 8 that illuminates a reticle surface Ra, which is a pattern surface of a reticle R (mask), with exposure illumination light (exposure light) IL.
- the illumination device 8 includes a light source 10 that generates illumination light IL, an illumination optical system ILS that illuminates the reticle surface Ra with the illumination light IL from the light source 10, and an illumination control unit 36.
- the exposure apparatus EX further includes a reticle stage RST that moves the reticle R, a projection optical system PL that projects an image of the pattern of the reticle R onto the surface of the wafer W (substrate), a wafer stage WST that moves the wafer W, A main control system 35 composed of a computer that comprehensively controls the operation of the entire apparatus and various control systems are provided.
- the Z axis is set parallel to the optical axis of the projection optical system PL
- the X axis is parallel to the plane of FIG. 1 in the plane perpendicular to the Z axis
- the Y axis is perpendicular to the plane of FIG. Will be described.
- the scanning direction of the reticle R and the wafer W during exposure is a direction parallel to the Y axis (Y direction).
- the rotational directions (inclination directions) around the axes parallel to the X axis, the Y axis, and the Z axis will be described as the ⁇ x direction, the ⁇ y direction, and the ⁇ z direction.
- an ArF excimer laser light source that emits a pulse of linearly polarized laser light having a predetermined temporal and spatial coherency, which is narrowed to a wavelength of 193 nm, is used.
- a KrF excimer laser light source that supplies laser light having a wavelength of 248 nm, or a harmonic generator that generates harmonics of laser light output from a solid-state laser light source (YAG laser, semiconductor laser, etc.) is also used. it can.
- linearly polarized illumination light IL composed of laser light emitted from a light source 10 controlled by a power supply unit (not shown) is a transmission optical system including a beam expander 11, and 1 for adjusting the polarization direction.
- the light is incident on a diffractive optical element (DOE) 13A through a two-wavelength plate 12.
- DOE diffractive optical element
- the diffractive optical element 13A is for annular illumination, and the diffractive optical element 13A has a large intensity in an annular region as shown in FIG. 3A on an incident surface 25I of a fly-eye lens 25 described later.
- a light intensity distribution is formed.
- a dotted circle 49 is a region where the coherence factor ( ⁇ value) is 1.
- the diffractive optical element 13A is supported by a turret plate 33, and the turret plate 33 also supports a diffractive optical element 13B for other different illumination conditions (normal illumination, quadrupole illumination, dipole illumination, etc.).
- the illumination control unit 36 rotates the turret plate 33 via the drive unit 33a and installs a diffractive optical element corresponding to the illumination condition in the illumination optical path, thereby satisfying the illumination condition.
- a corresponding light intensity distribution is set.
- the illumination light IL that has passed through the diffractive optical element 13A enters the polarization unit 15.
- the polarization unit 15 includes an incident optical system 14 that converts the illumination light IL from the diffractive optical element 13A into parallel light, a first light beam IL1 that is P-polarized light from the illumination light IL that has passed through the incident optical system 14, and a second light beam that is S-polarized light.
- the polarization unit 15 includes a mirror 17 that reflects the first light beam IL1 transmitted through the first PBS, a deformable mirror 18 that reflects the second light beam IL2 reflected by the first PBS 16, and a first light reflected by the mirror 17.
- a second PBS 22 that coaxially synthesizes the light beam IL1 and the second light beam IL2 reflected by the deformable mirror 18 along the optical axis AXI of the illumination optical system ILS, and its A quarter-wave plate 23 (polarization state variable element) is provided in the optical path of the light beams IL1 and IL2 synthesized coaxially and varies the polarization state of the synthesized light beams IL1 and IL2.
- the second PBS 22 includes an axis obtained by extending the optical axis of the incident optical system 14 bent by the partial optical system (17) through which the first light beam IL1 passes, and a partial optical system (18) through which the second light beam IL2 passes.
- a partial optical system (18) through which the second light beam IL2 passes.
- the polarization separation / combination plane of the second PBS may be disposed at the intersecting position.
- the optical system disposed between the first PBS and the second PBS in the optical path through which the first light beam IL1 passes can be referred to as a first partial optical system
- the first PBS in the optical path through which the second light beam IL2 passes can be referred to as a second partial optical system.
- the deformable mirror 18 includes a mirror 19 that reflects the second light beam IL, a holder 20 that holds the mirror 19, and a plurality of extendable drive elements 21 (for example, piezo elements) arranged in a matrix on the back surface of the mirror 19. And have.
- the illumination control unit 36 controls the amount of expansion / contraction of the many drive elements 21, whereby the shape of the reflection surface of the mirror 19 can be deformed within the range of the wavelength level of the illumination light IL.
- the illumination light IL emitted from the quarter wavelength plate 23 of the polarization unit 15 can be controlled in various ways in the polarization direction (details will be described later).
- the illumination light IL emitted from the polarization unit 15 enters the incident surface 25I of the fly-eye lens 25 through the relay optical system 24 including the first lens system 24a and the second lens system 24b.
- the relay optical system 24 By the relay optical system 24, the reflecting surface of the mirror 19 of the deformable mirror 18 is optically conjugate with the incident surface 25I.
- the fly-eye lens 25 has a large number of lens elements arranged in close contact with each other in the Z direction and the Y direction, and the exit surface of the fly-eye lens 25 is the pupil plane of the illumination optical system ILS (hereinafter referred to as the illumination pupil plane). ) IPP (surface conjugate with the exit pupil).
- a surface light source including a large number of secondary light sources (light source images) is formed on the exit surface (illumination pupil plane IPP) of the fly-eye lens 25 by wavefront division.
- the fly-eye lens 25 Since the fly-eye lens 25 has a large number of optical systems arranged in parallel, the light intensity distribution on the entrance surface 25I is directly transmitted to the illumination pupil plane IPP which is the exit surface.
- the entrance plane 25I is a plane equivalent to the illumination pupil plane IPP, and the arbitrary light intensity distribution and the arbitrary polarization distribution of the illumination light IL formed on the entrance plane 25I are directly used as the light intensity distribution on the illumination pupil plane IPP and It becomes a polarization distribution.
- the incident surface 25I is optically almost conjugate with the reticle surface. Note that a microlens array may be used instead of the fly-eye lens 25.
- Illumination light IL from the surface light source formed on the illumination pupil plane IPP includes a first relay lens 28, a reticle blind (field stop) 29, a second relay lens 30, an optical path bending mirror 31, and a condenser optical system.
- the illumination area of the reticle surface Ra is illuminated with a uniform illuminance distribution via the reference numeral 32.
- the illumination optical system ILS is configured including the beam expander 11, the half-wave plate 12, the diffractive optical element 13A, the polarization unit 15, and the optical system from the relay optical system 24 to the condenser optical system 32.
- Each optical member of the illumination optical system ILS is supported by a frame (not shown).
- the pattern in the illumination area of the reticle R is transferred to one shot area of the wafer W via the telecentric projection optical system PL on both sides (or one side on the wafer side).
- the image is projected onto the exposure area at a predetermined projection magnification (for example, 1/4, 1/5, etc.).
- the illumination pupil plane IPP is conjugate with the pupil plane (a plane conjugate with the exit pupil) of the projection optical system PL.
- the wafer W includes a wafer having a photoresist (photosensitive material) coated at a predetermined thickness on the surface of a base material such as silicon.
- the reticle R is attracted and held on the upper surface of the reticle stage RST, and the reticle stage RST is movable on the upper surface of the reticle base (not shown) (surface parallel to the XY plane) at a constant speed in the Y direction, and at least X It is mounted so as to be movable in the direction, the Y direction, and the ⁇ z direction.
- the two-dimensional position of the reticle stage RST is measured by a laser interferometer (not shown). Based on this measurement information, the main control system 35 receives the position and speed of the reticle stage RST via a drive system 37 including a linear motor and the like. To control.
- wafer W is sucked and held on the upper surface of wafer stage WST via a wafer holder (not shown), and wafer stage WST is moved in the X and Y directions on the upper surface of the wafer base (not shown) (a surface parallel to the XY plane). It can move and can move at a constant speed in the Y direction.
- the two-dimensional position of wafer stage WST is measured by a laser interferometer (not shown), and based on this measurement information, main control system 35 moves the position and speed of wafer stage WST via drive system 38 including a linear motor and the like. To control.
- An alignment system (not shown) for aligning the reticle R and the wafer W is also provided.
- the polarization unit 15 in FIG. 1 will be described with reference to FIG.
- the illumination light IL that has passed through the half-wave plate 12 and the diffractive optical element 13A is incident on the first PBS 16 via the incident optical system 14.
- the first PBS 16 splits a P-polarized first light beam IL1 whose polarization direction is the X direction and a S-polarized second light beam IL2 whose polarization direction is the Y direction.
- the intensity ratio of the linearly polarized first light beam IL1 and second light beam IL2 whose polarization directions are orthogonal to each other is such that the half-wave plate 12 is slightly rotated about the optical axis and incident on the first PBS 16 Adjustment is possible by finely adjusting the polarization direction 40A of the light IL (see FIG. 2B). In the present embodiment, it is preferable to adjust the half-wave plate 12 so that the intensity ratio between the first light beam IL1 and the second light beam IL2 is 1: 1.
- the illumination light IL incident on the first PBS 16 is converted into parallel light by the incident optical system 14.
- the incident optical system 14 also has a function of simultaneously forming a light intensity distribution formed on the incident surface 25I on the reflecting surface of the mirror 19 of the deformable mirror 18.
- the reflecting surface of the mirror 19 is also conjugate with the incident surface 25I of the fly-eye lens 25 by the relay optical system 24.
- the first light beam IL1 is reflected by the mirror 17 toward the second PBS 22, and the second light beam IL2 is reflected by the mirror 19 of the deformable mirror 18 toward the second PBS 22.
- the linearly polarized first light beam IL1 and second light beam IL2 are combined coaxially along the optical axis AXI parallel to the X axis by the second PBS 22, and enter the quarter-wave plate 23 as illumination light IL.
- the polarization direction 40B of the first light beam IL1 incident on the quarter-wave plate 23 is the Z direction as shown in FIG. 2C
- the polarization direction 40C is the Y direction as shown in FIG.
- the direction of the fast axis (optical axis) 48 of the quarter-wave plate 23 is set to a direction that intersects the Y axis at 45 °, that is, a direction that intersects the polarization directions 40B and 40C at 45 °.
- the first light beam IL1 passing through the quarter-wave plate 23 becomes right circularly polarized light indicated by a polarization direction 41B, for example, and the second light beam IL1 passing through the quarter-wave plate 23 is left shown by a polarization direction 41C, for example. It becomes circularly polarized light.
- the first light beam IL1 and the second light beam IL2 that pass through the quarter-wave plate 23 are circularly polarized light in opposite directions, and there is a phase difference at each position in the radial direction and the circumferential direction.
- the illumination light IL that passes through each position becomes linearly polarized light that is directed in various directions according to the phase difference.
- the polarization states in the beam cross sections of the first light beam IL1 and the second light beam IL2 that have passed through the quarter-wave plate 23 and are combined have linearly polarized light directed in different directions. Therefore, the polarization state of the illumination light IL that is incident on the incident surface 25I of the fly-eye lens 25 is a set of linearly polarized light that has various polarization directions according to the phase difference distribution.
- the Jones vector is a vector composed of polarization components in two directions orthogonal to the target light.
- the polarization direction 40A of the incident illumination light IL shown in FIG. 2B is inclined at 45 ° with respect to the Y axis
- the axis parallel to the polarization direction 40A is the x axis
- the x axis is within the XY plane.
- the orthogonal axis is taken as the y axis.
- the Jones vector composed of the x-axis and y-axis polarization components of the incident illumination light IL is as shown on the left side of the following equation (1).
- the Jones vectors of the first light beam IL1 and the second light beam IL2 branched by the first PBS 16 are the first and second vectors on the right side of Equation (1), respectively.
- the phase difference ⁇ is given to the second light beam IL2 by the deformable mirror 18, the Jones vector of the second light beam IL2 becomes as shown on the right side of the equation (2).
- the Jones vector of the combined illumination light IL is as follows.
- the action of the quarter wave plate 23 is expressed in the Jones matrix as follows.
- the finally obtained illumination light IL is linearly polarized light, and the polarization direction of the linearly polarized light is rotated according to the phase difference ⁇ imparted by the deformable mirror 18.
- the angle ( ⁇ / 2) of the polarization direction may be within a range of ⁇ 90 ° (0 to 180 °).
- the displacement ⁇ t in the normal direction at each point of the reflecting surface of the mirror 19 is the illumination light IL.
- the wavelength ⁇ may be within the following range ( ⁇ 180 ° in terms of phase).
- the intensity distribution of the illumination light IL on the incident surface 25I is a distribution in which the intensity increases in a ring-shaped region as shown in FIG.
- the intensity distribution of the first light beam IL1 and the second light beam IL2 on the incident surface 25I also increases in intensity in the ring-shaped region 42A in FIG. 2C and the ring-shaped region 43A in FIG. Distribution.
- the deformable mirror 18 sets the phase difference between the light beams IL1 and IL2 so as to gradually change in the circumferential direction ⁇ within the region 43A. Accordingly, as an example, the polarization state of the illumination light IL on the incident surface 25I is changed to the radial directions 44A, 44B, 44C,...
- the optical axis AXI within the annular zone can be set to be a set of polarized linearly polarized light.
- the polarization state of the illumination light IL on the incident surface 25I is set in the circumferential direction 45A, 45B, 45C, with respect to the optical axis AXI within the annular zone. It can be set so as to be a set of linearly polarized light polarized to.
- the polarization state in the annular zone can be set to a distribution in an arbitrary polarization direction.
- the diffractive optical element 13B when the diffractive optical element 13B is installed in the illumination optical path in FIG. 1, the light intensity distribution on the incident surface 25I of the fly-eye lens 25 increases in intensity in a circular region as shown in FIG. Distribution.
- the polarization state of the illumination light IL on the incident surface 25I is changed to a direction 46A parallel to the Z axis shown in FIG.
- FIG. 1 the diffractive optical element 13B is installed in the illumination optical path in FIG. 1
- the polarization state of the illumination light IL on the incident surface 25I is changed to a direction 46A parallel to the Z axis shown in FIG.
- the polarization direction of the illumination light IL incident on the polarization unit 15 may be set to the X direction or the Y direction. Furthermore, it is possible to set a substantially non-polarized state by giving a random phase difference distribution by the deformable mirror 18.
- the light intensity distribution on the entrance surface 25I of the fly-eye lens 25 has four regions 47A to 47D (or 90 °) as shown in FIG.
- the distribution is such that the intensity increases in the rotated region.
- the polarization state of the illumination light IL on the incident surface 25I is changed in the circumferential direction 46C shown in FIG. It can be set to linearly polarized light, linearly polarized light in the radial direction 46D shown in FIG. 5C, or any other distribution of polarization directions.
- step 102 of FIG. 6 the reticle R is loaded onto the reticle stage RST of FIG.
- step 104 the main control system 35, for example, information on the target distribution of the light intensity distribution and the target distribution of the polarization state on the illumination pupil plane IPP (illumination conditions) from the exposure data file according to the pattern of the reticle R to be exposed. ).
- the light intensity distribution (light quantity distribution) on the incident surface 25I and consequently the illumination pupil plane IPP is obtained.
- the shape of the reflecting surface of the mirror 19 of the deformable mirror 18 is controlled via the illumination controller 36 in accordance with the target distribution of the polarization state, and the phase difference distribution between the light beams IL1 and IL2 is determined.
- the distribution of the polarization direction at each position on the entrance surface 25I and thus the illumination pupil plane IPP is set.
- the wafer W coated with the photoresist is loaded on the wafer stage WST.
- emission of the illumination light IL from the light source 10 is started (step 110), and then the illumination light IL is irradiated onto the first PBS 16 of the polarization unit 15 through the half-wave plate 12 (step 114).
- the first light beam IL1 and the second light beam IL2 are branched (separated) from the illumination light IL by the first PBS 16 (step 116).
- the phase difference distribution between the light beams IL1 and IL2 is controlled by controlling the phase distribution of the second light beam IL2 by the deformable mirror 18 (step 118).
- the light beams IL1 and IL2 are coaxially combined by the second PBS 22 (step 120), and the distribution of the polarization direction of the illumination light IL is targeted by the combined illumination light IL passing through the quarter-wave plate 23. (Step 122). Note that the irradiation of the illumination light IL to the wafer W is controlled by opening and closing the variable blind in the reticle blind 29 of FIG.
- the reticle stage RST and the wafer stage are exposed while exposing a part of one shot region of the wafer W with an image of the projection optical system PL of a part of the pattern of the reticle R under the illumination light IL.
- the shot area of the wafer W is scanned and exposed by moving the reticle R and the wafer W in the Y direction synchronously with the projection magnification being the speed ratio via the WST. If an unexposed shot area remains in the next step 126, the wafer W is stepped to the scanning start position via the wafer stage WST in step 128, and the next shot area is scanned in the next step 124. Exposure is performed. In this manner, each shot area of the wafer W is exposed by the step-and-scan method.
- the emission of the illumination light IL is stopped in step 130, and the next wafer is exposed in step 132.
- the image of the pattern of the reticle R can be formed with high resolution on the entire shot area of the wafer W with the desired light intensity distribution and the desired arbitrary polarization distribution. Can be exposed.
- the illumination device 8 of the present embodiment includes the illumination optical system ILS, and the illumination device 8 illuminates the reticle surface Ra with the illumination light IL.
- the illumination optical system ILS has a polarization unit 15.
- the polarization unit 15 is an optical system that changes the polarization state of the illumination light IL supplied from the light source 10, and separates the first light beam IL1 and the second light beam IL2 whose polarization directions are orthogonal to each other from the illumination light IL.
- the first PBS 16 (step 116), a deformable mirror 18 disposed in the optical path of the second light beam IL2 and providing a variable phase difference distribution between the light beams IL1 and IL2 (step 118), and a variable phase difference distribution are provided.
- a second PBS 22 for synthesizing the luminous fluxes IL1 and IL2 coaxially (step 120). Furthermore, the polarization unit 15 includes a quarter wavelength plate 23 disposed in the optical path of the illumination light IL obtained by combining the light beams IL1 and IL2. By passing the light beams IL1 and IL2 (illumination light IL) synthesized by the second PBS 22 through the quarter-wave plate 23, the phase difference distribution is obtained from two circularly polarized lights in opposite directions to which a variable phase difference distribution is given. A distribution of linearly polarized light having a polarization direction corresponding to is generated (step 122).
- the light beams IL1 and IL2 having a variable phase difference distribution and whose polarization directions are orthogonal to each other are synthesized coaxially.
- the quarter-wave plate 23 By passing the light beam obtained by combining the two light beams IL1 and IL2 through the quarter-wave plate 23, two circularly polarized light beams in opposite directions to which a variable phase difference distribution is given are obtained.
- the polarization state of the illumination light IL obtained by synthesizing the two circularly polarized lights becomes a distribution of linearly polarized light having various polarization directions according to the variable phase difference distribution. Therefore, the reticle surface Ra can be illuminated with light having various distributions of polarization directions.
- the second PBS 22 does not necessarily synthesize the light beams IL1 and IL2 coaxially.
- an optical system that separates two reversely rotating circularly polarized light from incident light is used instead of the first PBS 16
- elements such as wave plates such as 1/2 or 1/8, polarizers, light polarizers or the like that change the polarization state are used, or these elements are combined to change the polarization state. It may be variable.
- the exposure apparatus EX of the present embodiment is an exposure apparatus that illuminates the pattern of the reticle R with the illumination light IL for exposure and exposes the wafer W with the illumination light IL through the pattern and the projection optical system PL.
- the apparatus 8 is provided, and the illumination light from the illumination apparatus 8 is used as the illumination light IL.
- this exposure apparatus EX since the pattern can be illuminated with the illumination light IL having the distribution of the optimum polarization direction according to the pattern of the reticle R, images of various patterns can be exposed on the wafer W with high resolution.
- a movable multi-mirror spatial light modulator (SLM) having a large number of minute mirror elements each having a variable position in the normal direction of the reflecting surface is used. Also good.
- SLM spatial light modulator
- Reference 1 “Yijian Chen et al.,“ Design and fabrication of tilting and piston micromirrors for maskless lithography, ”Proc. Of SPIE (USA) Vol. pp.1023-1037 (2005) ”or Reference 2“ D. Lopez et al., “Two-dimensional MEMS array for maskless lithography and wavefront modulation,” Proc. of SPIE (USA) Vol. 6589, 65890S (2007) Can be used.
- the arrangement of the polarization unit 15 in the illumination optical system ILS is not limited to the arrangement shown in FIG. 1, and can be arranged at any position where an arbitrary polarization distribution is required.
- the polarization unit 15 may be disposed in front (upstream) of the diffractive optical element 13A (or other diffractive optical element) in FIG.
- the polarization direction of the light incident on the diffractive optical element 13A and the like can be made different depending on the position, and the light flux in each polarization direction is diffracted to an arbitrary position on the incident surface 25I (and thus the illumination pupil plane IPP).
- the exit pupil of the illumination optical system ILS having an arbitrary polarization distribution can be formed.
- a polarization unit 15A of the first modification shown in FIG. 7 may be used instead of the polarization unit 15 of FIG.
- a polarization unit 15A includes a polarization beam splitter (hereinafter referred to as PBS) 16A and a parallel plane plate each coated with a polarization beam splitter film, instead of the prism-type first PBS 16 and second PBS 22 of FIG.
- PBS polarization beam splitter
- the other configuration is the same as that of the polarization unit 15. Since the PBSs 16A and 22A made of parallel flat plates are inexpensive and have high durability, the polarizing unit 15A can be maintained at low cost and with a wide maintenance interval.
- the polarization unit 15B of the second modification shown in FIG. 8 may be used instead of the polarization unit 15A of FIG.
- the polarization unit 15 ⁇ / b> B is obtained by replacing the PBS 16 ⁇ / b> A in FIG. 7 with a normal half mirror 61 and a half-wave plate 62.
- the P-polarized illumination light IL from the incident optical system 14 is divided into a first light beam IL1 and a second light beam IL2 by the half mirror 61, and the first light beam IL1 is reflected by the mirror 17 and becomes P-polarized light. Incident on PBS 22A.
- the second light beam IL2 is converted into S-polarized light by the half-wave plate 62, then reflected by the deformable mirror 18, enters the PBS 22A, and is synthesized coaxially with the first light beam IL1.
- the cost is further reduced.
- the polarization unit 15C of the third modification shown in FIG. 9 may be used instead of the polarization unit 15 of FIG.
- the polarization unit 15C includes a first PBS 16B having a rhombic cross section for separating the illumination light IL from the incident optical system 14 into a first light beam IL1 and a second light beam IL2 whose polarization directions are orthogonal, and a light beam IL1. , IL2 and the deformable mirror 18, respectively, and a second PBS 22B having a diamond-shaped cross section for synthesizing the reflected light beams IL1 and IL2 coaxially.
- the other configuration is the same as that of the polarization unit 15.
- a mirror for bending the optical path is not necessary, and the incident axis and the emission axis of the illumination light IL can be arranged on the same axis, so that manufacture (assembly / adjustment) is easy.
- a reflective deformable mirror 18 is used in FIG. 1, but as shown by a polarization unit 15D of the fourth modification in FIG. 10A.
- a transmission type optical system may be used.
- a transmissive variable polarization element 63 is disposed in place of the mirror 17 and deformable mirror 18 in FIG. 9, and light beams IL1 and IL2 emitted from the first PBS 16B are parallel variable polarization elements. The light is incident on the second PBS 22 ⁇ / b> B through 63 and is synthesized coaxially.
- the variable polarization element 63 includes a glass plate divided into a large number of minute segments 63a, a heating element 63d provided so that each segment 63a hardly affects the luminous flux, It has a horizontal signal line 63b and a vertical signal line 63c for supplying a current to the heating element 63d of the segment 63a.
- the refractive index of the specific segment 63a can be changed to give an arbitrary phase distribution to the wavefront of the light beam passing through the variable polarization element 63. Is possible. Accordingly, in FIG.
- the polarization distribution of the illumination light transmitted through the quarter-wave plate 23 is changed to an arbitrary polarization direction. It can be a distribution.
- the transmission type variable polarization element 63 is not a method in which the specific segment 63a is heated by the heating element 63d, but a method in which the specific segment 63a is heated by infrared rays irradiated from the outside to change its refractive index. It may be used. Further, instead of the glass plate, a plurality of elements having an electro-optic effect may be used, and an electric field or a magnetic field may be applied to a specific element to change the refractive index of the element (overall refractive index distribution). . Further, the polarization unit 15E of the fifth modification shown in FIG. 11 may be used instead of the polarization unit 15 of FIG. In FIG.
- a polarization unit 15E includes a mirror 64 having two reflecting surfaces for reflecting the illumination light IL from the incident optical system 14, a first light beam IL1 of P-polarized light from the reflected illumination light IL, and a first S-polarized light beam IL1.
- PBS 16B that separates the two light beams IL2, a quarter-wave plate 65 that converts the separated light beams IL1 and IL2 into circularly polarized light in the reverse direction, and a variable phase difference distribution between the circularly polarized light beams IL1 and IL2.
- a deformable mirror 18 for reflecting.
- the light beams IL1 and IL2 reflected by the deformable mirror 18 become S-polarized light and P-polarized light through the quarter-wave plate 65, respectively, they are synthesized coaxially by the PBS 16B and reflected by the mirror 64.
- the reflected light beam enters the fly-eye lens 25 via the quarter-wave plate 23 and the relay optical system 24.
- the polarization unit 15E only one PBS 16B is required, and an arbitrary phase difference distribution can be accurately given between the light beams IL1 and IL2.
- a Wollaston prism may be used in place of the polarizing beam splitter or the mirror provided with the polarizing beam splitter film.
- FIG. 12A shows a main part of the illumination device 8A of the exposure apparatus of the present embodiment.
- the illumination device 8A illuminates the illuminated surface (reticle surface Ra in FIG. 1) with illumination light in an arbitrary polarization state obtained from the light source 10 and linearly polarized illumination light IL supplied from the light source 10.
- an illumination control unit 36A is included in the illumination device 8A.
- Other configurations are the same as those of the exposure apparatus EX of FIG.
- linearly polarized illumination light IL composed of laser light emitted from a light source 10 passes through a beam expander 11 and a half-wave plate 12 and is a first spatial light modulation of a movable multi-mirror system.
- SLM instrument
- the first spatial light modulator 70 for example, the one disclosed in US Pat. No. 7,095,546 or US Patent Application Publication No. 2005/0095749 can be used.
- the modulation control unit 39A controls the inclination angle around the two axes of each mirror element 71 of the spatial light modulator 70 in accordance with the illumination condition instructed from the illumination control unit 36A, whereby the light quantity distribution on the illumination pupil plane IPP.
- the illumination light IL reflected by the array of mirror elements 71 of the spatial light modulator 70 enters the polarization unit 15F.
- the polarization unit 15F includes an incident optical system 14 that converts the illumination light IL from the spatial light modulator 70 into parallel light, a first P-polarized light beam from the illumination light IL that has passed through the incident optical system 14, and a second S-polarized light beam.
- PBS flat polarizing beam splitter
- SLM phase modulation type second spatial light modulator
- a quarter-wave plate 23 disposed in the optical path of a light beam obtained by combining the reflected second light beam and the first light beam reflected by the spatial light modulator 73 and transmitted through the PBS 76 along the optical axis
- the second spatial light modulator 73 has a large number of via the drive unit 77 on the surface of the base member 75 so that the position of the surface in the normal direction is variable.
- a two-dimensional array of small mirror elements 74 is supported.
- the PBS film 76 a of the PBS 76 is disposed close to the array of mirror elements 74 of the spatial light modulator 73.
- the amount of change in the phase of the first light beam reflected by the mirror element 74 is proportional to the displacement ⁇ tf. is doing.
- the amount of change in the phase is within a range of ⁇ 180 °, for example.
- the modulation control unit 39 ⁇ / b> B controls the change amount of the phase of the light beam reflected by each mirror element 74 via each drive unit 77.
- the phase modulation type spatial light modulator 73 for example, the one disclosed in Reference Document 1 or Reference Document 2 described above can be used.
- the illumination light IL emitted from the polarization unit 15F is incident on the incident surface FP4 of the microlens array 25M via the relay optical system 24 and the mirror 17.
- a surface light source composed of a number of secondary light sources (light source images) is formed on the exit surface (illumination pupil plane IPP) of the microlens array 25M by wavefront division.
- the entrance plane FP4 is equivalent to the illumination pupil plane IPP. Due to the relay optical system 24, the average reflecting surface FP2 of the array of mirror elements 74 of the second spatial light modulator 73 is optically substantially conjugate with the incident surface FP4.
- the incident optical system 14 causes the average reflective surface FP1 of the array of mirror elements 71 of the first spatial light modulator 70 to optically substantially Fourier transform with the reflective surface FP2 of the second spatial light modulator 73.
- a surface FP3 optically conjugate with the reflecting surface FP1 of the first spatial light modulator 70 is formed between the lens systems 24a and 24b of the relay optical system 24.
- the illumination optical system ILSA includes the beam expander 11, the half-wave plate 12, the first spatial light modulator 70, the optical system from the polarization unit 15 to the microlens array 25M, and the first relay lens 28 in FIG.
- the optical system up to the condenser optical system 32 is included.
- the S-polarized second light beams ILA 2 and ILB 2 of the illumination lights ILA and ILB are obtained from the PBS 76.
- the light is reflected by the PBS film 76a and travels toward the quarter-wave plate 23.
- the P-polarized first light beams ILA1 and ILB1 out of the illumination lights ILA and ILB are transmitted through the PBS 76, reflected by the corresponding mirror element 74 of the spatial light modulator 73, and transmitted through the PBS 76 and transmitted through the quarter wavelength plate. Head to 23.
- any different phase difference can be given between the light beams ILA1, ILA2 and the light beams ILB1, ILB2 whose polarization directions are orthogonal to each other.
- the light beams ILAS and ILBS obtained by combining the light beams ILA1 and ILA2 and the light beams ILB1 and ILB2 pass through the quarter-wave plate 23, so that the light beams ILAS and ILBS are respectively spatial light modulators, as in the embodiment of FIG.
- the linearly polarized light is polarized in the direction corresponding to the phase difference given at 73.
- the reflection surface FP2 of the spatial light modulator 73 is substantially conjugate with the incident surface FP4 equivalent to the illumination pupil plane IPP, the displacement of each mirror element 74 is controlled independently of each other, so that The distribution of the polarization direction of the illumination light IL can be easily controlled to an arbitrary distribution.
- the polarization unit 15F is disposed on the downstream side of the first spatial light modulator 70.
- the polarization unit 15F may be arranged on the upstream side of the spatial light modulator 70.
- the fly-eye lens 25 that is the wavefront division type integrator of FIG. 1 is used as an optical integrator.
- the optical integrator a rod type integrator as an internal reflection type optical integrator can be used.
- Step 221 to be performed Step 222 to manufacture a mask (reticle) based on this design step, Step 223 to manufacture a substrate (wafer) which is a base material of the device, Mask exposure by the exposure apparatus EX or the exposure method of the above-described embodiment Process of exposing pattern to substrate, process of developing exposed substrate, substrate processing step 224 including heating (curing) and etching process of developed substrate, device assembly step (dicing process, bonding process, packaging process, etc.) Including the process) 225, as well as the inspection step 226 etc. It is manufactured Te.
- the device manufacturing method includes the steps of exposing the substrate (wafer W) through the mask pattern using the exposure apparatus EX or the exposure method of the above embodiment, and processing the exposed substrate. (I.e., developing the resist on the substrate and forming a mask layer corresponding to the mask pattern on the surface of the substrate; and processing the surface of the substrate through the mask layer (heating, etching, etc.) ) Processing step).
- the polarization state of the illumination light can be easily optimized according to the pattern on the mask, so that the electronic device can be manufactured with high accuracy.
- the present invention can also be applied to an immersion type exposure apparatus disclosed in, for example, US Patent Application Publication No. 2007/242247 or European Patent Application Publication No. 1420298.
- the present invention can be applied to an illumination optical apparatus that does not use a condenser optical system.
- the present invention can also be applied to a proximity type exposure apparatus that does not use a projection optical system.
- the present invention is not limited to the application to the manufacturing process of a semiconductor device.
- a manufacturing process such as a liquid crystal display element and a plasma display, an imaging element (CMOS type, CCD, etc.), a micromachine, a MEMS ( Microelectromechanical systems), thin film magnetic heads, and various devices (electronic devices) such as DNA chips can be widely applied.
- EX ... exposure device, ILS ... illumination optical system, R ... reticle, PL ... projection optical system, W ... wafer, 8 ... illumination device, 10 ... light source, 12 ... 1/2 wavelength plate, 13A, 13B ... diffractive optical element ( DOE), 15, 15A to 15E: Polarization unit, 16, 22 ... PBS (polarization beam splitter), 18 ... Deformable mirror, 23 ... 1/4 wavelength plate, 24 ... Relay optical system, 25 ... Fly eye lens, 36 ... Lighting control unit
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Abstract
Description
また、第4の態様によれば、光源から供給される光の偏光状態を変化させる光学系ユニットが提供される。この光学系ユニットは、その光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離する分離光学系と、その第1光束及びその第2光束の少なくとも一方の光路に配置されて、その第1光束及びその第2光束の間の位相差分布を変える可変光学系と、位相差分布が変えられたその第1光束及びその第2光束を合成する合成光学系と、その合成光学系によって合成された光束の光路に配置され、その合成された光束の偏光状態を変更する偏光状態可変素子と、を備えるものである。
また、第8の態様によれば、本発明の態様の露光方法又は露光装置を用いて基板上に感光層のパターンを形成することと、そのパターンが形成されたその基板を処理することと、を含むデバイス製造方法が提供される。
図1は本実施形態に係る露光装置EXの概略構成を示す。露光装置EXは、一例としてスキャニングステッパー(スキャナー)よりなる走査露光型の露光装置(投影露光装置)である。図1において、露光装置EXは、露光用の照明光(露光光)ILでレチクルR(マスク)のパターン面であるレチクル面Raを照明する照明装置8を備えている。照明装置8は、照明光ILを発生する光源10と、光源10からの照明光ILでレチクル面Raを照明する照明光学系ILSと、照明制御部36とを備えている。さらに、露光装置EXは、レチクルRを移動するレチクルステージRSTと、レチクルRのパターンの像をウエハW(基板)の表面に投影する投影光学系PLと、ウエハWを移動するウエハステージWSTと、装置全体の動作を統括的に制御するコンピュータよりなる主制御系35と、各種制御系等とを備えている。
言い換えると、第2PBS22は、第1光束IL1が通過する部分光学系(17)によって折り曲げられた入射光学系14の光軸を延長した軸と、第2光束IL2が通過する部分光学系(18)によって折り曲げられた入射光学系14の光軸を延長した軸とが交差する位置で第1光束IL1及び第2光束IL2を合成するように配置されている。第2PBSの偏光分離・合成面が上記交差する位置に配置されても良い。ここで、第1光束IL1が通過する光路において第1PBSと第2PBSとの間に配置される光学系を第1部分光学系と称することができ、第2光束IL2が通過する光路において第1PBSと第2PBSとの間に配置される光学系を第2部分光学系と称することができる。
なお、図2(A)において、ミラー19の反射面を点線の面A1で示すように変形させると、反射光の位相が変化するとともに、変形量の微分値(局所的な傾斜の変化量)に応じて反射方向も変化する。しかしながら、本実施形態では、ミラー19の反射面とフライアイレンズ25の入射面25Iとを共役に配置しているため、入射面25Iで照明光ILが到達する位置が変化せず、容易に所望の偏光分布を得ることができる。
まず、図6のステップ102において、レチクルRが図1のレチクルステージRSTにロードされる。次のステップ104において、主制御系35は、露光対象のレチクルRのパターンに応じて、例えば露光データファイルから照明瞳面IPPにおける光強度分布の目標分布及び偏光状態の目標分布の情報(照明条件)を読み出す。そして、照明制御部36を介して照明光路に回折光学素子13A,13B等のいずれかの回折光学素子を設置することによって、入射面25I、ひいては照明瞳面IPPにおける光強度分布(光量分布)を設定する。次のステップ106において、その偏光状態の目標分布に応じて、照明制御部36を介してデフォーマブルミラー18のミラー19の反射面の形状を制御して、光束IL1,IL2間の位相差分布を設定する。これによって、入射面25I、ひいては照明瞳面IPPの各位置における偏光方向の分布が設定される。
また、1/4波長板23の代わりに、1/2や1/8等の波長板、偏光子、施光子などの偏光状態を可変する素子を用いたり、これらの素子を組み合わせて偏光状態を可変してもよい。
また、本実施形態の露光装置EXは、露光用の照明光ILでレチクルRのパターンを照明し、照明光ILでそのパターン及び投影光学系PLを介してウエハWを露光する露光装置において、照明装置8を備え、照明装置8からの照明光を照明光ILとして使用している。この露光装置EXによれば、レチクルRのパターンに応じて最適な偏光方向の分布を持つ照明光ILでそのパターンを照明できるため、種々のパターンの像をそれぞれ高い解像度でウエハWに露光できる。
先ず、デフォーマブルミラー18の代わりに、それぞれ反射面の法線方向の位置が可変の多数の微小なミラー要素を有する可動マルチミラー方式の空間光変調器(SLM:spatial light modulator)を使用してもよい。このような位相変調型の空間光変調器としては、例えば参考文献1「Yijian Chen et al., “Design and fabrication of tilting and piston micromirrors for maskless lithography,”Proc. of SPIE (米国) Vol. 5751, pp.1023-1037 (2005)」又は参考文献2「D. Lopez et al., “Two-dimensional MEMS array for maskless lithography and wavefront modulation,”Proc. of SPIE (米国) Vol. 6589, 65890S (2007)」に開示されているものを使用可能である。
さらに、ガラス板の代わりに、電気光学効果を有する複数の素子を使用して、特定の素子に電界又は磁界を印加してその素子の屈折率(全体の屈折率分布)を変化させてもよい。
また、図1の偏光ユニット15の代わりに図11に示す第5変形例の偏光ユニット15Eを使用してもよい。図11において、偏光ユニット15Eは、入射光学系14からの照明光ILを反射する2つの反射面を持つミラー64と、反射された照明光ILからP偏光の第1光束IL1とS偏光の第2光束IL2とを分離するPBS16Bと、分離された光束IL1,IL2を逆方向の円偏光に変換する1/4波長板65と、円偏光の光束IL1,IL2間に可変の位相差分布を付与して反射するデフォーマブルミラー18とを有する。この場合、デフォーマブルミラー18で反射された光束IL1,IL2は、1/4波長板65を介してそれぞれS偏光及びP偏光となるため、PBS16Bで同軸に合成されてミラー64で反射される。反射された光束は1/4波長板23及びリレー光学系24を介してフライアイレンズ25に入射する。この偏光ユニット15Eによれば、PBS16Bが一つでよく、さらに光束IL1,IL2間に正確に任意の位相差分布を付与できる。
図12(A)は、本実施形態の露光装置の照明装置8Aの要部を示す。照明装置8Aは、光源10と、光源10から供給される直線偏光の照明光ILから得られる任意の偏光状態の照明光で被照射面(図1のレチクル面Ra)を照明する照明光学系ILSAと、照明制御部36Aとを備えている。その他の構成は図1の露光装置EXと同様である。
また、上記の実施形態の露光装置EX又は露光方法を用いて半導体デバイス等の電子デバイス(マイクロデバイス)を製造する場合、この電子デバイスは、図13に示すように、デバイスの機能・性能設計を行うステップ221、この設計ステップに基づいたマスク(レチクル)を製作するステップ222、デバイスの基材である基板(ウエハ)を製造するステップ223、前述した実施形態の露光装置EX又は露光方法によりマスクのパターンを基板に露光する工程、露光した基板を現像する工程、現像した基板の加熱(キュア)及びエッチング工程などを含む基板処理ステップ224、デバイス組み立てステップ(ダイシング工程、ボンディング工程、パッケージ工程などの加工プロセスを含む)225、並びに検査ステップ226等を経て製造される。
なお、本発明は、例えば米国特許出願公開第2007/242247号明細書、又は欧州特許出願公開第1420298号明細書等に開示されている液浸型露光装置にも適用できる。さらに、本発明は、コンデンサー光学系を使用しない照明光学装置にも適用可能である。さらに、本発明は、投影光学系を用いないプロキシミティ方式等の露光装置にも適用することができる。
また、本願に記載した上記公報、各国際公開パンフレット、米国特許、又は米国特許出願公開明細書における開示を援用して本明細書の記載の一部とする。また、明細書、特許請求の範囲、図面、及び要約を含む2011年9月16日付け提出の米国仮特許出願第61/535,654号の全ての開示内容は、そっくりそのまま引用して本願に組み込まれている。
Claims (24)
- 光源から供給される光で被照射面を照明する照明光学装置において、
前記光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離する分離光学系と、
前記第1光束及び前記第2光束の少なくとも一方の光路に配置されて、前記第1光束及び前記第2光束の間の位相差分布を変える可変光学系と、
位相差分布が変えられた前記第1光束及び前記第2光束を合成する合成光学系と、
を備えることを特徴とする照明光学装置。 - 前記合成光学系によって合成された光束の光路に配置され、前記合成された光束の偏光状態を変更する偏光状態可変素子を備えることを特徴とする請求項1に記載の照明光学装置。
- 光源から供給される光で被照射面を照明する照明光学装置において、
前記光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離する分離光学系と、
前記第1光束及び前記第2光束の少なくとも一方の光路に配置されて、前記第1光束及び前記第2光束の間の位相差分布を変える可変光学系と、
位相差分布が変えられた前記第1光束及び前記第2光束を合成する合成光学系と、
前記合成光学系によって合成された光束の光路に配置され、前記合成された光束の偏光状態を変更する偏光状態可変素子と、
を備えることを特徴とする照明光学装置。 - 前記可変光学系は、前記第1光束が通過する第1部分光学系と、前記第2光束が通過する第2部分光学系とを備え、
前記合成光学系は、前記第1部分光学系の前記合成光学系側の光軸と、前記第2部分光学系の前記合成光学系側の光軸とが交差する位置に配置されることを特徴とする請求項1~3のいずれか一項に記載の照明光学装置。 - 前記合成光学系は、前記第1光束及び前記第2光束を合成する合成面を備え、
該合成面は前記交差する位置に配置されることを特徴とする請求項4に記載の照明光学装置。 - 前記可変光学系は、前記第1光束及び前記第2光束の一方の位相差分布を変えることを特徴とする請求項1~5のいずれか一項に記載の照明光学装置。
- 前記偏光状態可変素子は、前記第1光束及び前記第2光束を互いに逆方向の円偏光状態に変更し、
前記合成された前記第1光束及び前記第2光束の光束断面における偏光状態は、互いに異なる方向を向く直線偏光を有することを特徴とする請求項2又は3に記載の照明光学装置。 - 前記偏光状態可変素子は、1/4波長板であることを特徴とする請求項7に記載の照明光学装置。
- 前記可変光学系は、前記第1光束又は前記第2光束の光路に配置されて、反射面の形状が部分的に変形可能な反射部材を含むことを特徴とする請求項1~8のいずれか一項に記載の照明光学装置。
- 前記分離光学系及び前記合成光学系の少なくとも一方は偏光ビームスプリッターであることを特徴とする請求項1~9のいずれか一項に記載の照明光学装置。
- 前記分離光学系は、前記光源から供給される光を分割するハーフミラーと、該ハーフミラーで分割された一方の光束の光路に配置されて前記光束の偏光方向を回転する光学素子とを含むことを特徴とする請求項1~9のいずれか一項に記載の照明光学装置。
- 前記第1光束及び前記第2光束は偏光方向が互いに直交した直線偏光であることを特徴とする請求項1~11のいずれか一項に記載の照明光学装置。
- 前記分離光学系に入射する光の光路に配置されて、前記光の偏光方向を調整する波長板を備えることを特徴とする請求項1~11のいずれか一項に記載の照明光学装置。
- 前記分離光学系に入射する光の光路に配置されて、前記照明光学装置の照明光路における所定の位置に光の光量分布を形成する光量分布形成光学系と、
前記合成光学系によって合成された光束の光路に配置され、前記合成された光束を波面分割して前記光の光量分布と等価な光量分布を持つ面光源を形成する面光源形成光学系と、
を備えることを特徴とする請求項1~13のいずれか一項に記載の照明光学装置。 - 前記可変光学系は、前記照明光学装置の射出瞳又はこの射出瞳と共役な面と等価な面の近傍に配置されることを特徴とする請求項14に記載の照明光学装置。
- 前記可変光学系は、前記第1光束又は前記第2光束の光路中であって前記照明光学装置の射出瞳又はこの射出瞳と共役な面と等価な面の近傍に配置されて、反射面の形状が部分的に変形可能な反射部材を含むことを特徴とする請求項15に記載の照明光学装置。
- 露光光でパターンを照明し、前記露光光で前記パターン及び投影光学系を介して基板を露光する露光装置において、
請求項1~16のいずれか一項に記載の照明光学装置を備え、
前記照明光学装置からの光を前記露光光として用いることを特徴とする露光装置。 - 光源から供給される光の偏光状態を変化させる光学系ユニットであって、
前記光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離する分離光学系と、
前記第1光束及び前記第2光束の少なくとも一方の光路に配置されて、前記第1光束及び前記第2光束の間の位相差分布を変える可変光学系と、
位相差分布が変えられた前記第1光束及び前記第2光束を合成する合成光学系と、
前記合成光学系によって合成された光束の光路に配置され、前記合成された光束の偏光状態を変更する偏光状態可変素子と、
を備えることを特徴とする光学系ユニット。 - 前記可変光学系は、前記第1光束又は前記第2光束の光路に配置されて、反射面の形状が部分的に変形可能な反射部材を含むことを特徴とする請求項18に記載の光学系ユニット。
- 光源から供給される光で被照射面を照明する照明方法において、
前記光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離することと、
前記第1光束及び前記第2光束の間に可変の位相差分布を与えることと、
可変の位相差分布が与えられた前記第1光束及び前記第2光束を合成することと、
を含む照明方法。 - 前記合成された光束を波長板に通すことを含む請求項20に記載の照明方法。
- 光源から供給される光で被照射面を照明する照明方法において、
前記光源から供給される光から互いに偏光状態が異なる第1光束及び第2光束を分離することと、
前記第1光束及び前記第2光束の間の位相差分布を変えることと、
位相差分布が変えられた前記第1光束及び前記第2光束を合成することと、
前記合成光学系によって合成された光束を偏光状態可変素子に通すことと、
を含む照明方法。 - 露光光でパターンを照明し、前記露光光で前記パターン及び投影光学系を介して基板を露光する露光方法において、
請求項20~22のいずれか一項に記載の照明方法を用いて、前記被照射面へ向かう光を前記露光光として用いることを特徴とする露光方法。 - 請求項23に記載の露光方法を用いて基板上に感光層のパターンを形成することと、
前記パターンが形成された前記基板を処理することと、
を含むデバイス製造方法。
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