JP2008021767A - Illuminating optical device, exposure device and manufacturing method for devices - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating optical device capable of rapidly changing over illuminating conditions between an illumination in a first region and the illumination in a second region. <P>SOLUTION: The illuminating optical device illuminating a surface to be irradiated (M) on the basis of a light from a light source (1) has a first deflector advancing an outgoing beam along a first optical path, and a second deflector advancing the outgoing beam along a second optical path on the basis of a luminous flux from the light source. The illuminating optical device further has an optical-path changeover member (12) changing over the first optical path; and the second optical path and polarization changing members (13A and 13B) changing the polarized state of at least one luminous flux in a second luminous flux projected to a second illuminating region on the surface to be irradiated, along the first luminous flux and the second optical path projected to a first illuminating region on the surface to be irradiated along the first optical path. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination optical apparatus, an exposure apparatus, and a device manufacturing method, and more particularly to an illumination optical apparatus suitable for an exposure apparatus for manufacturing devices such as semiconductor elements, imaging elements, liquid crystal display elements, and thin film magnetic heads in a lithography process. It is about.

  In a photolithography process for manufacturing a semiconductor element or the like, a pattern image of a mask (or reticle) is projected and exposed onto a photosensitive substrate (a wafer coated with a photoresist, a glass plate, etc.) via a projection optical system. An exposure apparatus is used. In a normal exposure apparatus, one type of pattern is formed in one shot area (unit exposure area) on the photosensitive substrate.

  On the other hand, in order to improve the throughput, a double exposure method has been proposed in which two types of patterns are overprinted on the same shot region on the photosensitive substrate to form one composite pattern (see Patent Document 1). reference).

JP 2000-21748 A

  In the double exposure type exposure apparatus, for example, the first pattern area on the mask is illuminated under the first illumination condition, and the pattern of the first pattern area is transferred to one shot area on the photosensitive substrate. The second pattern area is illuminated under the second illumination condition, and the pattern of the second pattern area is transferred to the same shot area on the photosensitive substrate. In order to improve the throughput of the exposure apparatus, it is required to quickly switch the illumination condition between the illumination of the first pattern area and the illumination of the second pattern area.

  The present invention has been made in view of the above-described problems, and provides an illumination optical device capable of quickly switching illumination conditions between illumination in the first region and illumination in the second region. Objective. In addition, the present invention uses an illumination optical device that quickly switches illumination conditions between illumination in the first region and illumination in the second region, and uses a double exposure method to fine patterns on a photosensitive substrate with high throughput. An object of the present invention is to provide an exposure apparatus capable of performing exposure with the above method.

In order to solve the above problems, in the first embodiment of the present invention, in the illumination optical device that illuminates the illuminated surface based on light from the light source
A first deflecting unit that travels an emitted light beam along a first optical path based on a light beam from the light source; and a second deflecting unit that travels along a second optical path, wherein the first optical path and the first optical path An optical path switching member for switching between two optical paths;
Of the first luminous flux incident on the first illumination area on the illuminated surface along the first optical path and the second luminous flux incident on the second illumination area on the illuminated surface along the second optical path Provided is an illumination optical device comprising a polarization changing member that changes a polarization state of at least one light beam.

In the second embodiment of the present invention, in the illumination optical device that illuminates the illuminated surface based on the light from the light source,
A first deflecting unit that travels an emitted light beam along a first optical path based on a light beam from the light source; and a second deflecting unit that travels along a second optical path, wherein the first optical path and the first optical path An optical path switching member for switching between two optical paths;
Of the first luminous flux incident on the first illumination area on the illuminated surface along the first optical path and the second luminous flux incident on the second illumination area on the illuminated surface along the second optical path There is provided an illumination optical device comprising a distribution changing member that changes a light amount distribution in an angular direction of at least one light beam.

  According to a third aspect of the present invention, there is provided an exposure apparatus comprising the illumination optical apparatus according to the first or second aspect, and exposing a predetermined pattern illuminated by the illumination optical apparatus onto a photosensitive substrate. .

In the fourth embodiment of the present invention, using the exposure apparatus of the third embodiment, an exposure step of exposing the predetermined pattern to the photosensitive substrate;
And a developing process for developing the photosensitive substrate that has undergone the exposure process.

  In the illumination optical device of the present invention, the first region and the second region are sequentially individually illuminated under the required illumination conditions using the polarization state of the illumination light and the shape or size of the light intensity distribution at the illumination pupil as parameters. As a result, the illumination condition can be quickly switched between the illumination in the first area and the illumination in the second area. As a result, in the exposure apparatus of the present invention, a fine pattern is photosensitized by a double exposure method using an illumination optical device that quickly switches illumination conditions between illumination in the first region and illumination in the second region. The substrate can be exposed with high throughput, and a good device can be manufactured with high throughput.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the configuration and operation of the optical path switching member of FIG. In FIG. 1, the Z axis along the normal direction of the wafer W, which is a photosensitive substrate, the Y axis in the direction parallel to the plane of FIG. 1 in the plane of the wafer W, and the plane of the wafer W in FIG. The X axis is set in the direction perpendicular to the paper surface.

  Referring to FIG. 1, the exposure apparatus of this embodiment includes a light source 1 for supplying exposure light (illumination light). As the light source 1, for example, an ArF excimer laser light source that supplies light having a wavelength of about 193 nm, a KrF excimer laser light source that supplies light having a wavelength of about 248 nm, or the like can be used. The light beam emitted from the light source 1 along the optical axis AX is expanded into a light beam having a required cross-sectional shape by the shaping optical system 2 and enters the afocal lens 4 via the diffractive optical element 3 for circular illumination.

  In the afocal lens 4, the front focal position of the front lens group 4 a and the position of the diffractive optical element 3 substantially coincide, and the rear focal position of the rear lens group 4 b and the position of the predetermined surface 5 indicated by a broken line in the figure. It is an afocal system (non-focal optical system) set so as to be almost coincident. In general, a diffractive optical element is formed by forming a step having a pitch of the wavelength of exposure light (illumination light) on a substrate, and has a function of diffracting an incident beam to a desired angle.

  Specifically, the diffractive optical element 3 for circular illumination has a function of forming a circular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section is incident. Have. Therefore, the substantially parallel light beam incident on the diffractive optical element 3 forms a circular light intensity distribution on the pupil plane of the afocal lens 4 and then exits from the afocal lens 4 with a circular angular distribution. In the optical path between the front lens group 4a and the rear lens group 4b, a conical axicon system 6 is disposed on the pupil surface of the afocal lens 4 or in the vicinity thereof. The configuration and operation of the conical axicon system 6 will be described later.

  The light beam from the afocal lens 4 passes through a zoom lens (variable magnification optical system) 7 for varying a σ value (σ value = mask-side numerical aperture of the illumination system / mask-side numerical aperture of the projection optical system). The light enters the eye lens (or fly eye lens) 8. The micro fly's eye lens 8 is an optical element composed of a large number of microlenses having positive refractive power arranged vertically and horizontally and densely. In general, a micro fly's eye lens is configured by, for example, performing etching treatment on a plane-parallel plate to form a micro lens group.

  Here, each micro lens constituting the micro fly's eye lens is smaller than each lens element constituting the fly eye lens. Further, unlike a fly-eye lens composed of lens elements isolated from each other, a micro fly-eye lens is formed integrally with a large number of micro lenses (micro refractive surfaces) without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly eye lens in that lens elements having positive refractive power are arranged vertically and horizontally.

  The position of the predetermined surface 5 is disposed in the vicinity of the front focal position of the zoom lens 7, and the incident surface of the micro fly's eye lens 8 is disposed in the vicinity of the rear focal position of the zoom lens 7. In other words, the zoom lens 7 arranges the predetermined surface 5 and the incident surface of the micro fly's eye lens 8 substantially in a Fourier transform relationship, and consequently the pupil surface of the afocal lens 4 and the incident surface of the micro fly's eye lens 8. Are arranged almost conjugate optically.

  Therefore, for example, a circular illumination field centered on the optical axis AX is formed on the incident surface of the micro fly's eye lens 8, similarly to the pupil surface of the afocal lens 4. The overall shape of the circular illumination field changes in a similar manner depending on the focal length of the zoom lens 7. Each microlens constituting the micro fly's eye lens 8 has a rectangular cross section similar to the shape of the illumination area to be illuminated on the mask M (and thus the shape of the static exposure area to be formed on the wafer W).

  The light beam incident on the micro fly's eye lens 8 is two-dimensionally divided by a large number of microlenses, and has a light intensity distribution substantially the same as the illumination field formed by the incident light beam on the rear focal plane or in the vicinity of the illumination pupil. A secondary light source comprising a substantially surface light source having a circular shape centered on the optical axis AX. The light beam from the secondary light source formed on the rear focal plane of the micro fly's eye lens 8 or the illumination pupil in the vicinity thereof illuminates the mask blind 10 in a superimposed manner after passing through the condenser optical system 9.

  Thus, the mask blind 10 as the illumination field stop is formed with a rectangular illumination field that is elongated in the X direction, for example, according to the shape and focal length of each microlens constituting the micro fly's eye lens 8. The light beam that has passed through the rectangular opening (light transmission portion) of the mask blind 10 enters the optical path switching member 12 through the front lens group 11a of the imaging optical system 11 (reference numeral not shown). The optical path switching member 12 is disposed at or near the pupil position of the imaging optical system 11 in the optical path between the front lens group 11a and the rear lens group 11b of the imaging optical system 11. Hereinafter, it is assumed that light in the X-direction linearly polarized state that is polarized in the X direction is incident on the optical path switching member 12.

  Referring to FIG. 2, the optical path switching member 12 reflects the incident light beam and emits it along the first optical path, and the second reflection reflects the incident light beam and emits it along the second optical path. The surface 12b and a setting unit 12c that selectively sets only one of the first reflecting surface 12a and the second reflecting surface 12b in the illumination optical path. As shown in FIG. 2, when the first reflecting surface 12a of the optical path switching member 12 is set in the illumination optical path, the X-direction linearly polarized light beam incident on the first reflecting surface 12a is reflected on the first reflecting surface 12a. Reflected and guided to the first optical path.

  As shown in FIG. 3, the first light beam guided along the first optical path as shown by the solid line in FIG. 2 passes through the rear lens group 11b of the imaging optical system 11 and the first diffractive optical element 13A as shown in FIG. In the first pattern area PA1 on the mask M, a rectangular first illumination area IR1 elongated in the X direction is illuminated in a superimposed manner. Thus, the pattern corresponding to the first illumination region IR1 in the first pattern region PA1 of the mask M is illuminated with light in the X-direction linearly polarized state. The first diffractive optical element 13A disposed immediately before the mask M in the optical path between the optical path switching member 12 and the first illumination region IR1 divides the incident first light beam into two light beams, It has a function of deflecting the light beam by the same angle along a plane including the optical axis AX1 of the first optical path and parallel to the YZ plane.

  When the first diffractive optical element 13A does not intervene in the optical path, the first light beam circularly illuminates the pattern corresponding to the first illumination region IR1 with light in the X-direction linearly polarized state. On the other hand, in the present embodiment, the first diffractive optical element 13A functions as a distribution changing member that changes the light amount distribution in the angular direction of the first light beam incident on the first illumination region IR1, so the first light beam is the first light beam. The pattern corresponding to the illumination region IR1 is dipolarly illuminated with light in the X-direction linearly polarized state. As shown in FIG. 4 (a), the micro fly's eye lens 8 has an illuminating pupil in the vicinity of the rear focal plane or in the vicinity thereof. This is optically equivalent to forming a secondary light source in a polarized state and illuminating the first illumination region IR1 with light from the secondary light source.

Referring to FIG. 2 again, an optical rotator 14 is attached to the second reflecting surface 12b. The optical rotator 14 is made of quartz, which is an optical material having optical activity, and its crystal optical axis is set to substantially coincide with the optical axis AX. Hereinafter, the optical rotation of the crystal will be briefly described with reference to FIG. Referring to FIG. 5, a parallel plane plate-like optical member 100 made of quartz having a thickness d is arranged so that the crystal optical axis thereof coincides with the optical axis AX. In this case, due to the optical rotation of the optical member 100, the incident linearly polarized light is emitted in a state where the polarization direction is rotated by θ around the optical axis AX. At this time, the rotation angle (optical rotation angle) θ in the polarization direction due to the optical rotation of the optical member 100 is expressed by the following formula (1) by the thickness d of the optical member 100 and the optical rotation ρ of the crystal.
θ = d · ρ (1)

  In general, the optical rotation ρ of quartz has a wavelength dependency (a property in which the value of optical rotation varies depending on the wavelength of the light used: optical rotation dispersion), and specifically, it tends to increase as the wavelength of the light used decreases. is there. According to the description on page 167 of “Applied Optics II”, the optical rotation power ρ of quartz with respect to light having a wavelength of 250.3 nm is 153.9 degrees / mm. Specifically, the thickness of the optical rotator 14 (length in the optical axis direction) is set so that a 90 ° optical rotation angle is given to linearly polarized light by reciprocating passage.

  Therefore, when the setting unit 12c moves the optical path switching member 12 in the direction of the arrow F1 to set the second reflecting surface 12b in the illumination optical path, the X-direction linearly polarized state from the front lens group 11a of the imaging optical system 11 is changed. The light beam enters the second reflecting surface 12b via the optical rotator 14, is reflected by the second reflecting surface 12b, passes again through the optical rotator 14, and is guided to the second optical path in the Y-direction linearly polarized state. As shown by the broken line in FIG. 2, the second light beam guided along the second optical path passes through the rear lens group 11b of the imaging optical system 11 and the second diffractive optical element 13B as shown in FIG. In the second pattern area PA2 on the mask M, a rectangular second illumination area IR2 elongated in the X direction is illuminated in a superimposed manner.

  Thus, the pattern corresponding to the second illumination area IR2 in the second pattern area PA2 of the mask M is illuminated with the light in the Y-direction linearly polarized state. The second diffractive optical element 13B disposed immediately before the mask M in the optical path between the optical path switching member 12 and the second illumination region IR2 divides the incident second light beam into two light beams, The light beams are deflected by the same angle along a plane including the optical axis AX2 of the second optical path and parallel to the XZ plane. When the second diffractive optical element 13B is not interposed in the optical path, the second light beam circularly illuminates the pattern corresponding to the second illumination region IR2 with light in the Y-direction linearly polarized state.

  On the other hand, in the present embodiment, the second diffractive optical element 13B functions as a distribution changing member that changes the light amount distribution in the angular direction of the second light beam incident on the second illumination region IR2, and therefore the second light beam is the second light beam. The pattern corresponding to the illumination region IR2 is dipolarly illuminated with light in the Y-direction linearly polarized state. As shown in FIG. 4 (b), the micro fly's eye lens 8 has an illuminating pupil in the vicinity of the rear focal plane or in the vicinity thereof. This is optically equivalent to forming a secondary light source in a polarized state and illuminating the second illumination region IR2 with light from the secondary light source.

  Referring to FIG. 1 again, the first light flux from the first illumination region IR1 on the mask M held along the XY plane by the mask stage MS passes through the projection optical system PL to the XY plane by the wafer stage WS. A pattern image of the first pattern area PA1 is formed on the wafer (photosensitive substrate) W held along. Further, the second light flux from the second illumination area IR2 on the mask M forms a pattern image of the second pattern area PA2 on the wafer W via the projection optical system PL.

  In the present embodiment, one shot on the wafer W is illuminated while illuminating the first illumination region IR1 on the mask M and moving the mask M and the wafer W synchronously along the Y direction with respect to the projection optical system PL. The pattern is scanned and exposed in the first pattern area PA1. Next, the second illumination region IR2 on the mask M is illuminated, and the mask M and the wafer W are synchronously moved along the Y direction with respect to the projection optical system PL, while the second shot region on the wafer W is moved to the same shot region. The pattern of the pattern area PA2 is overlaid on the pattern of the first pattern area PA1, and scanning exposure is performed. Then, the above-described two scanning exposures, that is, double exposures, are repeated while moving the wafer W stepwise along the XY plane with respect to the projection optical system PL. A combined pattern of the pattern of the first pattern area PA1 and the pattern of the second pattern area PA2 is sequentially formed.

  The conical axicon system 6 includes, in order from the light source side (light incident side), a first prism member 6a having a plane facing the light source side and a concave conical refracting surface facing the mask side (light emission side), and a mask And a second prism member 6b having a convex conical refracting surface facing the light source side. The concave conical refracting surface of the first prism member 6a and the convex conical refracting surface of the second prism member 6b are complementarily formed so as to be in contact with each other. Further, at least one of the first prism member 6a and the second prism member 6b is configured to be movable along the optical axis AX, and the concave conical refracting surface of the first prism member 6a and the second prism member 6b. The distance from the convex conical refracting surface is variable.

  Hereinafter, the operation of the conical axicon system 6 and the operation of the zoom lens 7 will be described by paying attention to the annular secondary light source (a wide concept including a circular secondary light source). In a state in which the concave conical refracting surface of the first prism member 6a and the convex conical refracting surface of the second prism member 6b are in contact with each other, the conical axicon system 6 functions as a parallel flat plate, and is formed in an annular shape. There is no effect on the secondary light source. However, if the concave conical refracting surface of the first prism member 6a and the convex conical refracting surface of the second prism member 6b are separated, the width of the annular secondary light source (the outer diameter of the annular secondary light source) The outer diameter (inner diameter) of the ring-shaped secondary light source changes while keeping 1/2 of the difference from the inner diameter constant. That is, the circular secondary light source becomes an annular secondary light source, and the annular ratio (inner diameter / outer diameter) and size (outer diameter) of the annular secondary light source change.

  The zoom lens 7 has a function of enlarging or reducing the overall shape of the secondary light source in a similar (isotropic) manner. For example, by enlarging the focal length of the zoom lens 7 from a minimum value to a predetermined value, the overall shape of the secondary light source is similarly enlarged. In other words, due to the action of the zoom lens 7, both the width and size (outer diameter) change without changing the annular ratio of the annular secondary light source. As described above, the annular ratio and size (outer diameter) of the annular secondary light source can be controlled by the action of the conical axicon system 6 and the zoom lens 7.

  As described above, in the present embodiment, the incident light beam is reflected by the first reflecting surface 12a and emitted along the first optical path, and the incident light beam is reflected by the second reflecting surface 12b to enter the second optical path. By simply performing a simple operation of switching the position of the optical path switching member 12 with the optical rotator 14 between the second position and the second position, the illumination in the first illumination region IR1 in the X-direction linearly polarized state, The illumination of the second illumination region IR2 in the directional linear polarization state can be quickly switched. Further, the first diffractive optical element 13A as a distribution changing member that changes the light amount distribution in the angular direction of the first light beam incident on the first illumination region IR1, and the light amount in the angular direction of the second light beam incident on the second illumination region IR2. Due to the action of the second diffractive optical element 13B serving as a distribution changing member that changes the distribution, the first illumination region IR1 is dipolar in the X-direction linearly polarized state even though the diffractive optical element 3 for circular illumination is used. Illumination and the second illumination region IR2 can be dipolarly illuminated in the Y-direction linearly polarized state.

  That is, in the present embodiment, by the cooperative action of the optical path switching member 12, the diffractive optical elements 13A and 13B, and the optical rotator 14, the polarization state of the illumination light, the shape or size of the light intensity distribution at the illumination pupil, and the like are parameters. The first pattern area PA1 and the second pattern area PA2 can be individually and sequentially illuminated under the required illumination conditions as follows. As a result, the illumination conditions between the illumination of the first pattern area PA1 and the illumination of the second pattern area PA2 Can be quickly switched. As a result, in the exposure apparatus of the present embodiment, a double exposure method is used by using an illumination optical apparatus that quickly switches illumination conditions between illumination of the first pattern area PA1 and illumination of the second pattern area PA2. The fine pattern of the mask M can be exposed to the wafer W with high accuracy and high throughput.

  In general, in the exposure apparatus, it is preferable to illuminate the pattern of the mask M with light in a required linear polarization state so that the light irradiated onto the wafer W is in a polarization state mainly composed of S-polarized light. Here, the S-polarized light is linearly polarized light having a polarization direction in a direction perpendicular to the incident surface (polarized light having an electric vector oscillating in a direction perpendicular to the incident surface). Further, the incident surface is defined as a surface including the normal of the boundary surface at that point and the incident direction of light when the light reaches the boundary surface of the medium (the surface of the wafer W). Thus, the optical performance (focal point) of the projection optical system PL is obtained by illuminating the mask pattern with light in a required linearly polarized state so that the light irradiated onto the wafer W is in a polarization state mainly composed of S-polarized light. The depth and the like can be improved, and a pattern image with high contrast can be obtained on the wafer W.

  In the present embodiment, since the first diffractive optical element 13A functions as a distribution changing member during the scanning exposure of the pattern in the first pattern area PA1, the first light beam causes the pattern corresponding to the first illumination area IR1 to be linearly polarized in the X direction. Dipole illumination is performed by the light of the state. As described above, this is because the secondary light source in the Z-direction bipolar and X-direction linearly polarized state as shown in FIG. And illuminating the first illumination region IR1 with light from the secondary light source is optically equivalent. Thus, among the patterns in the first pattern area PA1 illuminated by the light in the first illumination area IR1, the light that forms an X-direction pattern extending in the X direction on the wafer W as the final irradiated surface is formed. A polarization state mainly composed of S-polarized light is obtained, and a high-contrast pattern image can be obtained on the wafer W.

  In addition, since the second diffractive optical element 13B functions as a distribution changing member during the scanning exposure of the pattern in the second pattern area PA2, the second light beam causes the pattern corresponding to the second illumination area IR2 to be light in the Y-direction linearly polarized state. Therefore, dipole illumination is performed. As described above, this is because the secondary light source in the X direction dipolar and Z direction linearly polarized as shown in FIG. 4B is formed on the rear focal plane of the micro fly's eye lens 8 or in the vicinity of the illumination pupil. And illuminating the second illumination region IR2 with light from the secondary light source is optically equivalent. In this way, among the patterns of the second pattern area PA2 illuminated by the light of the second illumination area IR2, the light that forms an elongated Y-direction pattern along the Y direction forms an image on the wafer W as the final irradiated surface. A polarization state mainly composed of S-polarized light is obtained, and a high-contrast pattern image can be obtained on the wafer W.

  In the above-described embodiment, the optical path switching member 12 reflects the incident light beam and emits it along the first optical path, and the first reflecting surface 12a reflects the incident light beam and emits it along the second optical path. 2 reflective surfaces 12b. However, the present invention is not limited to this, and various modifications can be made to the specific configuration of the optical path switching member. In general, the optical path switching member includes a first deflecting unit that travels the emitted light beam along the first optical path based on the light beam from the light source, and a second deflecting unit that travels along the second optical path. The optical path is configured to switch between the first optical path and the second optical path.

  In the above-described embodiment, the optical rotator attached to the second reflecting surface 12b of the optical path switching member 12 as a polarization changing member that changes the polarization state of the second light beam incident on the second illumination region IR2 on the mask M. 14 is provided. However, the present invention is not limited to this, and the polarization changing member can also be configured using a wave plate, a depolarizer (non-polarization element; depolarization element) or the like instead of the optical rotator (optical rotator). That is, the polarization changing member is configured to change the polarization state of at least one of the first light flux incident on the first illumination area on the irradiated surface and the second light flux incident on the second illumination area. It is important that various modifications can be made to the specific configuration, arrangement, etc. of the polarization changing member.

  In the above-described embodiment, as the first distribution changing member that changes the light amount distribution in the angular direction of the first light beam incident on the first illumination region IR1, the incident light beam is divided into two light beams and deflected by the same angle. As the second distribution changing member that uses the first diffractive optical element 13A to change the light amount distribution in the angular direction of the second light beam incident on the second illumination region IR2, the incident light beam is divided into two light beams and the same angle is obtained. The second diffractive optical element 13B that deflects only by the amount used is used. However, the present invention is not limited to this, and various modifications can be made to the specific configuration of the distribution changing member. That is, one of the diffractive optical elements 13A and 13B can be retracted from the optical path, or one or both can be replaced with a diffractive optical element having other diffraction characteristics.

  For example, by replacing the first diffractive optical element 13A with a diffractive optical element having other diffractive characteristics, the first illumination region IR1 is substantially rotated based on the light transmitted through the diffractive optical element 3 for circular illumination. It is possible to illuminate a band or to illuminate a plurality of poles other than substantially two poles. Similarly, by replacing the second diffractive optical element 13B with a diffractive optical element having other diffractive characteristics, the second illumination region IR2 is substantially reduced based on the light that has passed through the diffractive optical element 3 for circular illumination. It is possible to illuminate an annular zone or to illuminate a plurality of poles other than substantially two poles. Generally, the distribution changing member is configured to change the light amount distribution in the angular direction of at least one of the first light flux incident on the first illumination area and the second light flux incident on the second illumination area.

  Further, in the above-described embodiment, instead of the circular illumination diffractive optical element 3, the annular illumination is performed by setting a diffractive optical element for annular illumination or a diffractive optical element for multipole illumination in the illumination optical path. Or multipole illumination (dipole illumination, quadrupole illumination, etc.). That is, the diffractive optical elements 13A and 13B are retracted from the illumination optical path, and the first illumination area and the second illumination area are in different polarization states in an arbitrary illumination mode selected from, for example, annular illumination or multipolar illumination. Can be illuminated. Alternatively, at least one of the diffractive optical elements 13A and 13B is set in the optical path, or one or both of the diffractive optical elements is replaced with a diffractive optical element having other diffractive characteristics, so that the first illumination area can be changed with various modified illumination And the second illumination area can be illuminated.

  At this time, instead of the conical axicon system 6, a V-groove axicon system (not shown) or a pyramid axicon system (not shown) can be set on or near the pupil plane of the afocal lens 4. Here, the V-groove axicon system has a refracting surface having a V-shaped cross section that is substantially symmetric with respect to a predetermined axis passing through the optical axis, and the pyramid axicon system has a shape corresponding to the side surface of the pyramid centered on the optical axis. It has a refracting surface. For the configuration and action of the V-groove axicon system and the pyramid axicon system, reference can be made to JP-A-2002-231619.

  In the above-described embodiment, the first light beam reflected by the first reflecting surface 12a of the optical path switching member 12 and the second light beam reflected by the second reflecting surface 12b are both guided to one mask M. A first illumination region IR1 and a second illumination region IR2 are formed on M, respectively. However, the present invention is not limited to this, and the first illumination area is formed on the first mask M1 (not shown) by the first light beam reflected by the first reflection surface 12a of the optical path switching member 12, and the second reflection surface. The second illumination area can also be formed on the second mask M2 (not shown) by the second light beam reflected by 12b.

  In this case, the first mask M1, the second mask M2, and the wafer W are scanned in the scanning direction (Y direction) with respect to the double-headed projection optical system PL having two effective visual fields and one effective imaging region that are separated from each other. The pattern of the first mask M1 and the pattern of the second mask M2 are overlaid on one shot area on the wafer W while being moved in synchronization with each other to form one composite pattern. Then, the pattern of the first mask M1 and the second mask are formed in each shot area on the wafer W by repeating the above-described overlap scanning exposure while stepping the wafer W relative to the projection optical system PL. A composite pattern with the pattern of M2 is sequentially formed. As the double-headed projection optical system PL, for example, as shown in FIG. 6, a double-headed projection optical system PL comprising a refractive system and a deflecting mirror, or a catadioptric double-headed projection optical system PL as shown in FIG. Alternatively, a double-headed projection optical system PL using a beam splitter as shown in FIG. 8 can be used.

  In the above-described embodiment and each modification, the present invention is related to double exposure in which two types of patterns are overprinted on the same shot area on a photosensitive substrate (wafer) to form one composite pattern. Explains. However, the present invention is not limited to this, and the present invention is similarly applied to multiple exposure in which three or more types of patterns are overprinted on the same shot area on the photosensitive substrate to form one composite pattern. Can do.

  The illumination optical apparatus and the exposure apparatus according to the above-described embodiments and modified examples have various mechanical subsystems including the respective constituent elements recited in the claims of the present application with predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Manufactured by assembling to keep. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  In the exposure apparatus according to the above-described embodiment, the illumination optical device illuminates the mask (reticle) (illumination process), and the projection optical system is used to expose the transfer pattern formed on the mask onto the photosensitive substrate (exposure). Step), a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, referring to the flowchart of FIG. 9 for an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of this embodiment. I will explain.

  First, in step 301 of FIG. 9, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the one lot of wafers. Thereafter, in step 303, using the exposure apparatus of the present embodiment, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer.

  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, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is deposited on the wafer, a resist is applied on the metal film, and exposure, development, and etching processes are performed. Prior to these processes, on the wafer. It is needless to say that after forming a silicon oxide film, a resist may be applied on the silicon oxide film, and steps such as exposure, development, and etching may be performed.

  In the exposure apparatus of this 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. 10, in a pattern formation process 401, a so-called photolithography process is performed in which the exposure pattern of the present embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). 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 402.

  Next, in the color filter forming step 402, a large number of sets 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 forming step 402, a cell assembly step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.

  In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ). Thereafter, in a module assembling step 404, 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 above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

In the above-described embodiment, a KrF excimer laser light source or an ArF excimer laser light source is used as a light source. However, the present invention is not limited to this, and an exposure apparatus using another appropriate light source such as an F ₂ laser light source, for example. The present invention can also be applied to. In the above-described embodiment, the present invention has been described by taking an example of an illumination optical apparatus that is mounted on an exposure apparatus and illuminates a mask. However, a general illumination optical apparatus for illuminating a surface to be irradiated other than the mask. It is clear that the present invention can be applied to the present invention.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure explaining the structure and effect | action of an optical path switching member of FIG. (A) is a figure which shows the 1st illumination area | region which a 1st light beam forms in the 1st pattern area | region on a mask, (b) is a figure which shows the 2nd illumination area | region which a 2nd light beam forms in the 2nd pattern area | region on a mask. is there. (A) shows a bipolar secondary light source that the first light beam forms equivalently on the illumination pupil, and (b) shows a bipolar secondary light source that the second light beam forms equivalently on the illumination pupil. FIG. It is a figure explaining simply the optical rotatory power of quartz. It is a figure which shows roughly the structure of the double-headed type projection optical system which consists of a refraction system and a deflection | deviation mirror. It is a figure which shows schematically the structure of a catadioptric type double-headed type projection optical system. It is a figure which shows schematically the structure of the double-headed projection optical system which uses a beam splitter. It is a flowchart of the method at the time of obtaining the semiconductor device as a microdevice. It is a flowchart of the method at the time of obtaining the liquid crystal display element as a microdevice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 3 Diffractive optical element 4 Afocal lens 6 Conical axicon system 7 Zoom lens 8 Micro fly eye lens 9 Condenser optical system 10 Mask blind 11 Imaging optical system 12 Optical path switching member 13A, 13B Diffractive optical element (distribution change member)
14 Optical rotator (polarization changing member)
M Mask PL Projection optical system W Wafer

Claims (12)

In an illumination optical device that illuminates an illuminated surface based on light from a light source,
A first deflecting unit that travels an emitted light beam along a first optical path based on a light beam from the light source; and a second deflecting unit that travels along a second optical path, wherein the first optical path and the first optical path An optical path switching member for switching between two optical paths;
Of the first luminous flux incident on the first illumination area on the illuminated surface along the first optical path and the second luminous flux incident on the second illumination area on the illuminated surface along the second optical path An illumination optical apparatus, comprising: a polarization changing member that changes a polarization state of at least one light beam. The first deflecting unit has a first reflecting surface that reflects incident light and emits it along the first optical path, and the second deflecting unit reflects and emits incident light along the second optical path. A second reflecting surface; and the optical path switching member includes a setting unit that selectively sets only one of the first reflecting surface and the second reflecting surface in the illumination optical path. The illumination optical apparatus according to claim 1, wherein 3. The illumination optical apparatus according to claim 1, wherein the first deflection unit and the second deflection unit deflect an incident light beam at a position of an illumination pupil or a position in the vicinity thereof. The polarization changing member has at least one of an optical rotator, a wave plate, and a non-polarizing element arranged in an optical path between the optical path switching member and the irradiated surface. The illumination optical apparatus according to any one of 1 to 3. A distribution changing member that changes a light amount distribution in an angular direction of at least one of the first light flux incident on the first illumination area and the second light flux incident on the second illumination area is provided. The illumination optical apparatus according to any one of claims 1 to 4. The distribution changing member includes a first diffractive optical element disposed in an optical path between the optical path switching member and the first illumination area, and an optical path between the optical path switching member and the second illumination area. The illumination optical device according to claim 5, further comprising a second diffractive optical element disposed. In an illumination optical device that illuminates an illuminated surface based on light from a light source,
A first deflecting unit that travels an emitted light beam along a first optical path based on a light beam from the light source; and a second deflecting unit that travels along a second optical path, wherein the first optical path and the first optical path An optical path switching member for switching between two optical paths;
Of the first luminous flux incident on the first illumination area on the illuminated surface along the first optical path and the second luminous flux incident on the second illumination area on the illuminated surface along the second optical path An illumination optical apparatus comprising: a distribution changing member that changes a light amount distribution in an angular direction of at least one light beam. The distribution changing member includes a first diffractive optical element disposed in an optical path between the optical path switching member and the first illumination area, and an optical path between the optical path switching member and the second illumination area. The illumination optical apparatus according to claim 7, further comprising a second diffractive optical element disposed. 7. At least one of the first diffractive optical element and the second diffractive optical element is configured to be exchangeable with another diffractive optical element at a position immediately before the irradiated surface. Or the illumination optical apparatus of 8. An exposure apparatus comprising the illumination optical apparatus according to claim 1, wherein a predetermined pattern illuminated by the illumination optical apparatus is exposed on a photosensitive substrate. A first mask holding unit that holds a first mask having a first pattern; and a second mask holding unit that holds a second mask having a second pattern;
The exposure apparatus according to claim 10, wherein the illumination optical device forms the first illumination area on the first pattern and forms the second illumination area on the second pattern. An exposure step of exposing the predetermined pattern to the photosensitive substrate using the exposure apparatus according to claim 10 or 11,
And a developing step of developing the photosensitive substrate that has undergone the exposure step.

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