JP6651124B2 - Illumination optical system, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to an illumination optical system, an exposure apparatus, and a device manufacturing method.

  2. Description of the Related Art Exposure apparatuses used in manufacturing processes of semiconductor elements, flat panel displays, MEMS (microelectromechanical systems), and the like are known.

  In recent years, a solid-state ultraviolet light source using gallium nitride or the like has been developed, and it has been proposed to apply this type of solid-state ultraviolet light source to an illumination device of an exposure apparatus (for example, see Patent Document 1). In a solid-state ultraviolet light source, the absolute value of the amount of light emitted from each chip is not so large. Therefore, in order to obtain a required high illuminance on the surface to be illuminated, it is necessary to combine light from a plurality of chips and guide the combined light to the lighting device. At this time, in the illumination device, high illuminance uniformity is required over the entire area on the predetermined surface through which the illumination light passes.

US Patent Application Publication No. 2005 / 0219493A1

In the first embodiment, in an illumination optical system that illuminates a surface to be irradiated,
A first light emitting unit that emits first illumination light from the first light emitting surface;
A second light-emitting unit that emits second illumination light from a second light-emitting surface disposed at a distance from the first light-emitting surface;
A light-collecting member having a first light-collecting unit that collects the first illumination light from the first light-emitting surface and a second light-collecting unit that collects the second illumination light from the second light-emitting surface;
At least a part of the first illumination light having passed through the first condensing portion and the second illumination light having passed through the second condensing portion are conjugated to the illuminated surface or the illuminated surface. And a relay optical system for superimposing on a plane.

  According to a second aspect, there is provided an exposure apparatus including the illumination optical system according to the first aspect for illuminating a predetermined pattern provided on the surface to be irradiated, and exposing a substrate to the predetermined pattern. .

In a third mode, using the exposure apparatus of the second mode, exposing the predetermined pattern to the substrate,
Developing the substrate on which the predetermined pattern has been transferred, forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the substrate;
Processing the surface of the substrate via the mask layer.

FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus according to an embodiment. FIG. 2 is a diagram schematically illustrating an internal configuration of the illumination optical system in FIG. 1. FIG. 3 is a diagram illustrating a state in which images of a plurality of light emitting surfaces are formed in the vicinity of an emission end of a lens element. It is a figure showing the radiation angle characteristic of LED light source. FIG. 5 shows a state where a chip and a collector lens are viewed from an emission end of a lens element. It is a figure which shows the example of a numerical value which arrange | positioned several collector lenses almost densely. It is a figure which shows the modification using a lens array schematically. It is a figure which shows schematically the modification which guide | induces the light from a light source with a light guide. It is a figure which shows schematically the modification which performs deformed illumination using a diffractive optical element. It is a figure which shows the modification which omitted the fly-eye lens schematically. It is a figure showing signs that a plurality of chips turned on circularly. It is a figure showing signs that a plurality of chips turned on like a ring. 6 is a flowchart illustrating a manufacturing process of a semiconductor device. 5 is a flowchart illustrating a manufacturing process of a liquid crystal device such as a liquid crystal display element.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus according to an embodiment. In FIG. 1, the Z axis is set in the normal direction of the image plane of the projection optical system PL (that is, the direction of the optical axis AX of the projection optical system PL: the vertical direction on the paper surface of FIG. 1). The X axis is set parallel to the plane of FIG. 1, and the Y axis is set perpendicular to the plane of FIG. 1 in the image plane of the projection optical system PL.

  Referring to FIG. 1, the exposure apparatus of the present embodiment includes an illumination optical system IL that illuminates a mask (reticle) M on which a pattern to be transferred is formed. The internal configuration of the illumination optical system IL will be described later with reference to FIG. The illumination optical system IL illuminates, for example, the entire rectangular pattern area of the mask M, or an elongated slit-like area (for example, a rectangular area) along the X direction in the entire pattern area.

  The light from the pattern of the mask M forms a pattern image of the mask M on the unit exposure area of the substrate W coated with the photosensitive resist via the projection optical system PL. That is, in the unit exposure area of the substrate W, a rectangular area similar to the entire pattern area of the mask M or a rectangular area elongated in the X direction (optically) corresponds to the illumination area on the mask M optically. A mask pattern image is formed in the still exposure area).

  The substrate W is a single crystal wafer such as silicon in the case of a semiconductor exposure apparatus, and is a glass plate called a plate in the case of a liquid crystal exposure apparatus. The mask M is made of a light transmissive member, and the pattern formed on the surface has a shape necessary for forming a semiconductor element or a liquid crystal display element. In particular, when utilizing the optical proximity effect or the like, the image formed on the substrate W and the pattern formed on the mask M do not necessarily have similar shapes according to the magnification of the projection optical system PL. Absent.

  The mask M is held on the mask stage MS substantially parallel to the XY plane. A mechanism for moving the mask M in the X direction, the Y direction, the rotation direction around the Z axis, or the like is incorporated in the mask stage MS. The substrate W is held on the substrate stage WS substantially parallel to the XY plane. The substrate stage WS has a mechanism for moving the substrate stage WS (and thus the substrate W) in the X direction, the Y direction, the Z direction, the rotation direction around the X axis, the rotation direction around the Y axis, and the rotation direction around the Z axis. It has been incorporated.

  In the step-and-repeat method, a pattern image of the mask M is collectively exposed on one of a plurality of unit exposure regions set vertically and horizontally on the substrate W. After that, the control system CR moves the substrate stage WS stepwise along the XY plane, thereby positioning another unit exposure area of the substrate W with respect to the projection optical system PL. In this way, the operation of collectively exposing the pattern image of the mask M to the unit exposure area of the substrate W is repeated.

  In the step-and-scan method, the control system CR moves the mask stage MS and the substrate stage WS in the Y direction at a speed ratio according to the projection magnification of the projection optical system PL, and transfers the pattern image of the mask M onto the substrate W. Scan exposure is performed on one unit exposure area. Thereafter, the control system CR positions another unit exposure area of the substrate W with respect to the projection optical system PL by moving the substrate stage WS stepwise along the XY plane. Thus, the operation of scanning and exposing the pattern image of the mask M to the unit exposure area of the substrate W is repeated.

  That is, in the step-and-scan method, the mask stage MS and the substrate stage WS, and consequently, the mask M and the substrate W are moved along the Y direction which is the short side direction of the rectangular (generally slit-shaped) static exposure region. Are moved (scanned) synchronously with respect to the region having a width equal to the long side of the still exposure region on the substrate W and having a length corresponding to the scanning amount (moving amount) of the substrate W. The mask pattern is scanned and exposed.

  Referring to FIG. 2, the illumination optical system IL of the present embodiment includes an LED (Light Emission Diode) light source 1 as a solid state light source. The LED light source 1 includes a plurality of light emitting units arranged vertically and horizontally at an interval. Each light-emitting unit has a solid-state light-emitting element 1a that emits illumination light from a light-emitting surface. In the following description, the solid state light emitting device 1a having a light emitting surface is referred to as a chip 1a. However, in FIG. 2 and the related drawings, in order to facilitate understanding of the description and to clarify the drawing, the LED light source 1 has a total of six chips of two rows in the X direction and three rows in the Y direction. 1a, and its light emitting surface is circular. Note that the light emitting surface in the present embodiment may be a surface of the chip 1a from which light is emitted.

  Illumination light emitted from the light emitting surfaces of the six chips 1a is condensed by six collector lenses 2 arranged so as to correspond to the respective chips 1a, and then condensed to the fly-eye lens 4 via the relay lens 3. Incident. Each collector lens 2 is arranged such that its front focal position substantially coincides with the position of the light emitting surface of the corresponding chip 1a. The front focal position of the relay lens 3 substantially coincides with the surface on which the rear focal position of each collector lens 2 is located. Each collector lens 2 is arranged such that its optical axis is substantially parallel to the optical axis of the relay lens 3 (and, consequently, the optical axis AXi of the illumination optical system IL).

  The fly-eye lens 4 is an optical integrator having a number of lens elements (wavefront dividing elements) 4a arranged in parallel. In FIG. 2 and the related drawings, in order to facilitate understanding of the description and to clarify the drawing, the fly-eye lens 4 has five rows in the X direction and three rows in the Y direction as shown in FIG. It is assumed that there are a total of 15 lens elements 4a, and the cross section of each lens element 4a is a rectangular shape elongated in the X direction. The fifteen lens elements 4a are densely arranged, and the cross section of the fly-eye lens 4 is substantially square.

  Therefore, as shown by a thin solid line in FIG. 2, the light emitted from the center of the light emitting surface of each chip 1a becomes a substantially parallel light flux through the corresponding collector lens 2, and follows a path substantially parallel to the optical axis AXi. Incident on the relay lens 3. The six substantially parallel light beams incident on the relay lens 3 are condensed on the incident side surface of the fly-eye lens 4 located near the rear focal point.

  As shown by the broken line in FIG. 2, light emitted from the end of the light emitting surface of each chip 1a in a direction substantially parallel to the optical axis of the collector lens 2 (and thus substantially parallel to the optical axis AXi of the illumination optical system IL) After being condensed in the vicinity of the rear focal point 2, the light is projected by the action of the relay lens 3 on the incident side surface of the fly-eye lens 4 located in the vicinity of the rear focal plane. In this way, the illumination light from each chip 1a passes through the corresponding collector lens 2 and relay lens 3 and is superimposed on the incident side surface of the fly-eye lens 4.

  That is, the images of the circular light emitting surfaces of the respective chips 1 a of the LED light source 1 are formed so as to substantially overlap each other on the incident side surface of the fly-eye lens 4. At this time, the light emitting surface of each chip 1a of the LED light source 1 is projected by being enlarged to a size covering the effective area of the incident side surface of the fly-eye lens 4 by the action of the collector lens 2 and the relay lens 3.

  Each lens element 4a is configured such that the focal position on the incident side surface substantially coincides with the position on the exit surface, and the focal position on the exit surface approximately coincides with the incident side surface. Further, each lens element 4a is arranged such that its optical axis is substantially parallel to the optical axis AXi of the illumination optical system IL. The light beam incident on the fly-eye lens 4 is split into wavefronts by a plurality of lens elements 4a, and six small light sources 21, ie, six chips 1a, are located at positions near the exit ends of the lens elements 4a as shown in FIG. The image 21 of the light emitting surface is formed.

  In FIG. 3, the illumination light from each chip 1a is superimposed over a region that covers the entire incident side surface of the illustrated 15 lens elements 4a. Actually, as described above, a circular illumination field centered on the optical axis AXi is formed inside the substantially square incident surface of the fly-eye lens 4 as described above. Then, a large number of small light sources 21 distributed in a circular area centered on the optical axis AXi are provided at the output end of the fly-eye lens 4 so as to correspond to the circular illumination field formed on the incident side surface. Is formed.

  The light beam having passed through the plurality of lens elements 4a of the fly-eye lens 4 illuminates the mask M via an aperture stop 5 and a condenser lens 6 arranged near the exit end. The condenser lens 6 is arranged such that its front focal position substantially coincides with the position of the emission end of the fly-eye lens 4 and its rear focal position approximately coincides with the position of the pattern surface of the mask M. That is, the incident surface of each lens element 4a and the pattern surface of the mask M are optically substantially conjugated. The aperture stop 5 has, for example, a circular opening (light transmitting portion) centered on the optical axis AXi. Here, the surface on which the aperture stop 5 is arranged has an optically conjugate relationship with the surface on which the projection aperture stop (not shown) for determining the numerical aperture of the projection optical system PL is arranged.

  The image of the aperture stop 5 as viewed from the exit side of the illumination optical system IL is the exit pupil of the illumination optical system, and the aperture stop 5, which is a position optically conjugate with the exit pupil of the illumination optical system, is disposed. The surface that is present can be referred to as an illumination pupil. In the illumination pupil, a secondary light source (generally, a predetermined light intensity distribution in the illumination pupil) is formed as a substantial surface light source composed of a large number of light emitting portions by a plurality of lens elements 4a of the fly-eye lens. You. In other words, light from the plurality of lens elements 4a of the fly-eye lens 4 is distributed to the illumination pupil. The illumination pupil is defined as a position at which the illumination surface becomes a Fourier transform surface of the illumination pupil due to the action of an optical system between the illumination pupil and the illumination surface (in the case of an exposure apparatus, a mask or a wafer). May be defined.

  When the number of wavefront divisions by the fly-eye lens 4 (the number of lens elements 4a) is relatively large, the global light intensity distribution formed on the incident surface of the fly-eye lens 4 and the global light source as a whole The light intensity distribution (pupil intensity distribution) shows a high correlation. For this reason, the light intensity distribution on the incident surface of the fly-eye lens 4 and a surface optically conjugate with the incident surface may also be referred to as a pupil intensity distribution.

  Light beams from the plurality of lens elements 4 a of the fly-eye lens 4 are illuminated in a superimposed manner on the mask M via the condenser lens 6 after being restricted by the opening of the aperture stop 5. As a result, a rectangular illumination area elongated in the X direction is formed on the pattern surface (illuminated surface) of the mask M. In this manner, the light split on the incident side surface of the fly-eye lens 4 is projected via the condenser lens 6 so as to substantially overlap each other in the illumination area of the mask M, and the illuminance in the illumination area is averaged. Will be

In the present embodiment, the range expressed as “near” does not necessarily indicate the depth of focus (１ ／) × (λ / NA ² ) based on the numerical aperture NA of the imaging light beam, where λ is the light wavelength. In other words, the range is such that a decrease in light amount due to the spread of the illumination light beam can be ignored, that is, a range of approximately 2 × (λ / NA ² ). In the case of the LED light source 1, each chip 1a as a light emitting unit is considered to be a substantially perfect diffusion light source as shown in FIG. In FIG. 4, the radial direction corresponds to the radiation intensity of light, and the azimuth angle (the rotation direction about the origin) corresponds to the radiation angle of light.

  Therefore, the illuminance of light traveling from each chip 1a in an oblique direction at an angle θ is cos θ times the illuminance of light traveling in the normal direction at an angle of 0 from the light emitting surface of each chip 1a. That is, in order to capture the light from each chip 1a as efficiently as possible, it is necessary to capture the light greatly inclined from the normal line of the light emitting surface of each chip 1a by the collector lens 2. However, when the light that is greatly inclined is taken in by the collector lens 2, the peripheral light amount of the light beam passing through the collector lens 2 is attenuated by cos θ compared to the central light amount.

  For example, if the incident-side surface of the fly-eye lens 4 is configured to be Koehler-illuminated according to the related art disclosed in U.S. Patent Application Publication No. 2005 / 0219493A1, the amount of peripheral light is incident on the incident-side surface of the fly-eye lens 4. , An uneven illuminance distribution attenuated by cos θ with respect to the center light amount is formed. In this case, since the fly-eye lens 4 divides the incident light beam by the plurality of lens elements 4a and superimposes the light beam on the irradiation surface, even if the illuminance distribution of the light beam incident on the fly-eye lens 4 is not uniform, the irradiation surface Above, a substantially uniform illuminance distribution is obtained.

  However, the light beam split by the fly-eye lens 4 passes through each lens element 4a and reaches the emission end of the fly-eye lens 4. Since the exit end of the fly-eye lens 4 is located near the front focal position of the condenser lens 6, the state of the light amount distribution at the exit end of the fly-eye lens 4 and the amount of light in the angular direction of the light beam illuminating the mask M The state of the distribution will correspond. In other words, due to the non-uniform light amount distribution in which the peripheral light amount is smaller than the central light amount at the emission end of the fly-eye lens 4, the light flux illuminating the mask M is incident at an incident angle of 0 ° rather than the light which is vertically incident. Light with a large angle can provide a non-uniform irradiation angle characteristic with a small intensity. Here, the irradiation angle characteristic can be said to be the uniformity of the light intensity with respect to the incident angle of the illumination light.

  In the exposure apparatus, an aperture stop 5 is provided near the exit end of the fly-eye lens 4 for limiting the angle range of the illumination light beam. In order to resolve a finer pattern, it is necessary to take diffracted light having a larger diffraction angle into the projection optical system PL. Since the diffraction angle of the diffracted light due to the light from the periphery of the illumination light beam becomes the maximum diffraction angle that can be captured, if the intensity of the light around the angular distribution of the illumination light (light with a large incident angle) is weak, the diffracted light with a fine pattern However, there is a problem that the intensity is weak and sufficient contrast cannot be obtained.

  Further, when performing the deformed illumination, the opening of the aperture stop 5 may be formed in an annular shape in order to make the light intensity distribution in the illumination pupil an annular shape. Also in this case, it is desirable that the irradiation angle characteristics of the illumination light on the irradiation surface be uniform in order to minimize the decrease in the amount of light. In the present embodiment, the image of the light-emitting surface of each chip 1a, which is considered to be a substantially perfect diffusion light source, is projected onto the fly-eye lens 4 by projecting so as to substantially overlap the vicinity of the incident-side surface thereof. The light quantity distribution of the light beam can be made substantially uniform, and thus the irradiation angle characteristic of the illumination light on the irradiation surface can be made almost uniform.

  Except in special cases, when forming a pattern with an exposure apparatus, it is not desirable that the resolution differs depending on the direction of the pattern. Therefore, the opening of the aperture stop 5 is desirably rotationally symmetric about the optical axis AXi so that the angle range of the illumination light beam does not have azimuth dependence. Here, the azimuth dependence of the angle range of the illuminating light beam means that the angle range on the plane (meridional surface) containing the principal ray of the illuminating light beam is determined when the meridional surface is rotated around the principal ray. It can be said that the angle is constant. In the case of normal illumination in which the illumination light beam is limited to a predetermined aperture angle, the aperture of the aperture stop 5 is circular. When the light emitting surface of each chip 1a is rectangular, the aperture stop 5 is arranged so that the circular opening is substantially inscribed in the rectangular illumination field formed at the emission end of the fly-eye lens 4. Become.

  Here, light incident outside the circular opening cannot pass through the aperture stop 5, so that the light blocked by the aperture stop 5 does not contribute to illumination and causes a light amount loss. Even if the circular opening is completely inscribed in the square illumination field, 20% or more of the light cannot pass through the aperture stop 5. When the light emitting surface of the chip 1a, which is the light emitting portion of the LED light source 1, is circular when viewed from the direction of the optical axis AXi, the light becomes similar to the circular shape of the opening of the aperture stop 5, and is emitted from each chip 1a. Light loss can be minimized.

  By increasing the number of pairs of the chip 1a of the LED light source 1 and the collector lens 2, the illuminance on the pattern surface of the mask M, which is the surface to be irradiated (and, consequently, the exposed surface of the substrate 1) can be increased. However, in the fly-eye lens 4, the light emitted from the lens element 4 a (for example, adjacent to) different from the lens element 4 a on which the light is incident is largely bent and is not taken in the condenser lens 6, or is illuminated even if it is taken. It reaches outside the area. For this reason, it is necessary that the light emitted from the chip 1 a of the LED light source 1 enter the emission surface of the lens element 4 a of the fly-eye lens 4.

  That is, as shown in FIG. 5, the light emitting surface of each chip 1 a of the LED light source 1 and each collector lens 2 are projected from the output end of the lens element 4 a of the fly-eye lens 4 by the fly-eye lens 4 and the relay lens 3. Must be located within a certain range. FIG. 5 shows a state where each chip 1a and each collector lens 2 of the LED light source 1 are viewed from the emission end of the lens element 4a.

  In FIG. 5, a rectangular area 4aa indicated by a two-dot chain line indicates a range in which the emission end of the fly-eye element 4 is projected by the fly-eye lens 4 and the relay lens 7. Each chip 1a and each collector lens 2 of the LED light source 1 must be included in the range of the rectangular area 4aa. More strictly, each spot formed by the light from the light emitting surface of each chip 1 a formed at the rear focal position of each collector lens 2 is formed by the fly-eye lens 4 and the relay lens 7 at the emission end of the fly-eye element 4. It must be within the projected range 4aa.

  In order to effectively capture light from each chip 1a of the LED light source 1, the effective diameter of each collector lens 2 is larger than the effective diameter of each chip 1a. In the LED light source 1, the plurality of chips 1a are not in contact with each other. As a result, a cooling medium (cooling liquid) for cooling each chip 1a of the LED light source 1 is passed not only on the back surface side of the chip 1a but also on a portion other than the light emitting surface on the front surface side, so that better cooling efficiency is obtained. It is possible to get.

  Hereinafter, with the image-side numerical aperture of the projection optical system PL of 0.8 and the illumination coherence factor (σ value) of 0.8, the pattern of the mask M is set to 1 on a 30 mm × 10 mm rectangular unit exposure area on the substrate W. A numerical example when applied to an illumination optical system IL of an exposure apparatus that performs reduction exposure at a magnification of / 4 is shown. In order to perform the reduced exposure at a magnification of 縮小, on the mask M, an illumination area having a size four times as large as the unit exposure area, that is, a rectangular illumination area of 120 mm × 40 mm is required. The pattern area on the mask M is set slightly smaller than the illumination area in consideration of the installation error of the mask M and the like.

  Since the coherence factor of the illumination is 0.8, the numerical aperture of 0.16 (a numerical value obtained by multiplying the numerical aperture of 0.8 on the substrate W by 1/4 and the coherence factor of 0.8 of the illumination is 0.86). It is necessary to irradiate the illumination area of the mask M with light having a uniform intensity in an angle range of 9.2 ° in terms of an angle. As an example, the focal length of the collector lens 2 can be 400 mm, and the inner diameter (diameter) of the circular opening of the aperture stop 5 can be 128 mmφ.

  The fly-eye lens 4 may have a focal length of 20 mm, and the lens element 4a may have a rectangular cross section of 6 mm × 2 mm. The sectional size of 6 mm × 2 mm of the lens element 4 a is nothing less than the size of the 120 mm × 40 mm illumination area on the mask M projected by the relay lens 6 and the fly-eye lens 4. Since the fly-eye lens 4 needs to fill at least the inner region of the circular opening of the aperture stop 5, the fly-eye lens 4 is constituted by, for example, a lens element 4a of 22 steps × 64 steps.

  The focal length of the condenser lens 3 is set to 400 mm, the focal length of the collector lens 2 is set to 3 mm, and light from the chip 1 a having a circular light emitting surface with a diameter of 1 mm in the LED light source 1 is incident on the fly-eye lens 4 on the incident side. Is enlarged and projected on a circular area having a diameter of 133 mmφ. At this time, in the fly-eye lens 4, it is necessary that the illumination light is applied to the entire surface of the lens element 4 a corresponding to the outermost periphery of the circular opening of the aperture stop 5. Light incident on the partial region of the lens element 4a corresponding to the outside of the circular opening of the aperture stop 5 does not contribute to illumination, but loses light quantity. However, in order to maintain uniformity of illumination angle characteristics of illumination light. Required loss.

  When the collector lens 2 attempts to capture light in the range of up to 0.8 in terms of numerical aperture (light in the range of up to 53.1 ° in terms of angle) of the light from the chip 1a, at least 5. A diameter of 8 mmφ is required. Actually, the collector lens 2 needs a diameter of about 8 mmφ for aberration correction. The set of the chip 1a and the collector lens 2 needs to be within a range 4aa of 120 mm × 40 mm where the exit end of the lens element 4a of 6 mm × 2 mm is projected by the fly-eye lens 4 and the relay lens 3.

  As shown in FIG. 6, a maximum of 73 collector lenses 2 having a diameter of 8 mmφ can be arranged in a projection range 4aa of 120 mm × 40 mm. When the output per one chip 1a is 1W, the light output from the 73 chips 1a of the LED light source 1 is 73W. Since the take-in angle of the collector lens 2 is 0.8 in terms of numerical aperture, the take-up efficiency is 64% by squaring 0.8.

The optical surface of the illumination optical system IL is obtained by dividing the area ratio of the aperture of the aperture stop 5 to the illumination field formed on the surface on the incident side of the fly-eye lens 4 and the capture efficiency of 64% by the area of the illumination area over the light output 73W. The illuminance can be obtained while ignoring the effects of reflection at the surface and light absorption of the glass material. By performing the above calculation, an illuminance of 14.35 W / cm ² is obtained in the unit exposure area of the substrate W. Assuming that the light amount loss due to the reflection on the optical surfaces of the illumination optical system IL and the projection optical system PL and the absorption of the glass material is about 70%, an illuminance of 10 W / cm ² can be obtained in the unit exposure area of the substrate W.

  As described above, in the illumination optical system IL of the present embodiment, light from the light emitting surfaces of the multiple chips 1a is condensed by the multiple collector lenses 2 having optical axes substantially parallel to each other. The luminous flux passing through the plurality of collector lenses 2 is superimposed by the relay lens 3 on the incident side surface of the fly-eye lens 4 which is optically substantially conjugate with the pattern surface of the mask M, which is the irradiation surface. The light beams from the light emitting surfaces of the plurality of chips 1a are combined.

  In other words, the image of the light emitting surface of each chip 1a is projected so as to substantially overlap with the surface on the incident side of the fly-eye lens 4. As a result, the light amount distribution of the light beam incident on the fly-eye lens 4 can be made substantially uniform. The plane on the incident side of the fly-eye lens 4 can be regarded as a region on a predetermined plane through which the illumination light passes.

  Then, the illuminance distribution of the illumination light incident on the pattern surface of the mask M, which is the irradiated surface, can be made substantially uniform, and the illumination angle characteristics of the illumination light incident on the pattern surface can be made almost uniform. That is, in the present embodiment, it is possible to obtain high illuminance in the illumination region by combining light beams from the light emitting surfaces of the plurality of chips 1a while realizing uniformity of the illuminance and the irradiation angle characteristics in the illumination region on the mask M. Can be.

  In the above embodiment, the same number of the collector lenses 2 as the chips 1a are individually arranged so as to correspond to the plurality of chips 1a arranged at intervals. However, the present invention is not limited to this. Instead of a plurality of individually arranged collector lenses 2, a lens array 12 in which a plurality of lenses 12a are formed on a single light-transmitting substrate as shown in FIG. May be used. That is, a modification in which the plurality of collector lenses 2 in the embodiment of FIG. 2 are integrally formed is possible.

  Generally, the collector lens 2 in the embodiment of FIG. 2 functions as a light collecting unit that collects illumination light from the light emitting surface of the corresponding chip 1a. As the condensing part, not only a lens having a refraction function but also a mirror having a reflection function, a diffractive optical element having a diffraction function, or the like can be used. Further, a light-collecting member in which a plurality of light-collecting portions are individually provided or a light-collecting member in which a plurality of light-collecting portions are integrally formed can be used.

  Since the chip 1a, which is a light emitting unit, is formed on a substrate by a semiconductor process, the position accuracy is extremely high. On the other hand, when the number of chips 1a to be synthesized increases, it is difficult to arrange a large number of collector lenses 2 while aligning their optical axes. Therefore, a light-collecting member in which a plurality of light-collecting portions are integrally formed, such as the lens array 12, is also created with high precision using a semiconductor process, and alignment marks are formed on both the LED light source 1 and the lens array 12. There is an advantage that the work of positioning a large number of light-condensing parts with respect to a large number of chips 1a is facilitated by providing and overlaying these alignment marks.

  In the above-described embodiment, the illumination light from each chip 1a is applied via the corresponding collector lens 2 and relay lens 3 to a fly-eye that is optically substantially conjugated to the pattern surface of the mask M that is the surface to be irradiated. The light is superimposed on the incident side surface of the lens 4. That is, the conjugate surface optically conjugate with the pattern surface of the mask M, which is the irradiated surface, substantially coincides with the incident-side surface of the plurality of lens elements 4 a of the fly-eye lens 4. However, without being limited to this, the conjugate surface is positioned between the relay lens (relay optical system) and the condenser lens (condenser optical system), and illumination light from a plurality of light emitting surfaces is reflected by the conjugate surface. You may comprise so that it may overlap at least partially.

  In other words, a conjugate surface having an optically conjugate relationship with the light emitting surface of each chip 1a with respect to the optical system including each collector lens 2 and the relay lens 3 and a surface on the incident side of the plurality of lens elements 4a of the fly-eye lens 4 May not be made to coincide with each other in the optical axis direction. At this time, on the incident surface of the plurality of lens elements 4a of the fly-eye lens 4, the illumination light from the plurality of light emitting surfaces partially overlaps. Here, by changing the positional relationship, it is possible to change the illuminance distribution on the incident side surface of the plurality of lens elements 4a of the fly-eye lens 4.

  In the above embodiment, the LED light source 1 is used as the light source. However, without being limited to this, a light source having a plurality of light emitting units arranged at intervals, such as a semiconductor laser array, can be used. Further, as shown in FIG. 8, a modification is also possible in which light from a semiconductor laser (laser diode) 21 is made incident on an optical fiber (light guide) 23 by an input lens 22 to be guided. In the modification of FIG. 8, the emission surfaces 23 a of the plurality of optical fibers 23 are arranged as secondary light sources near the front focal position of the collector lens 2. That is, the emission surfaces 23a of the plurality of optical fibers 23 in the modification of FIG. 8 correspond to the light emitting surfaces of the plurality of chips 1a in the embodiment of FIG. The emission surface 23a as a light emitting surface has a shape such as a circle, a rectangle, and a polygon as necessary. Note that a portion of the fiber core on the emission surface 23a of the plurality of optical fibers 23, that is, a portion from which light is emitted may be used as the light emitting surface.

  FIG. 8 shows an example in which the light from the semiconductor laser 21 is guided to the optical fiber 23 by the input lens 22, but various configurations are possible for a specific configuration for guiding the light of the semiconductor laser 21 to the optical fiber 23. is there. Further, the light source 21 in the modified example of FIG. 8 is not limited to a semiconductor laser, but may be a solid-state light emitting device such as a fiber laser or an LED. When an optical fiber (light guide) is used, the light source arranged in front of the optical fiber can be freely arranged at an arbitrary distance, so that the light emitting portion can be sufficiently cooled. There is.

  When a solid-state ultraviolet light source is used as in the above-described embodiment, there is an advantage that the life is longer than that of a conventional ultra-high pressure mercury lamp. Further, since there is no problem that the replacement operation can be performed only after cooling when replacing the lamp, there is an advantage that the operation time of the apparatus can be extended. Further, the solid-state ultraviolet light source has an advantage that the conversion efficiency into light is higher than that of a mercury lamp, and the power to be used can be suppressed.

  In the above-described embodiment, light from the circular light emitting surfaces of the plurality of chips 1a is superimposed on the incident side surface of the fly-eye lens 4 to form a circular illumination field. However, without being limited to this, as shown in FIG. 9, a modification example in which the diffractive optical element 24 is arranged so as to be insertable into the optical path between the plurality of collector lenses 2 and the relay lens 3 is also possible. In FIG. 9, by arranging a diffractive optical element 24 as a deflecting member that changes the angle of the incident light and emits the light near the front focal position of the relay lens 3, an arbitrary surface is formed on the incident surface of the fly-eye lens 4. An example in which a shape illumination field (light quantity distribution) is formed is shown.

  As an example, the diffractive optical element 24 is disposed near the front focal position of the relay lens 3, and emits light from the circular light emitting surface of the chip 1 a, which is a light emitting unit, near the rear focal position of the relay lens 3. The light is converted into a light flux having an annular shape or another desired cross-sectional shape on the incident side surface of the fly-eye lens 4. Since the pattern on the diffractive optical element 24 is formed by Fourier transform, there is no positional dependency, and the diffractive optical element 24 may be arranged without being conscious of the position of the optical axis of the collector lens 2. That is, by changing the diffractive optical element 24 inserted in the optical path, the angular distribution of the illumination light can be changed to an arbitrary shape. That is, by inserting a diffractive optical element having required characteristics into the optical path using an unillustrated insertion / removal mechanism, the angular distribution of the illumination light can be selected as needed. The diffractive optical element 24 may be of a transmission type or a reflection type. Further, instead of or in addition to the diffractive optical element 24, a refractive optical element such as an axicon prism or a reflective optical element such as an axicon mirror may be used.

  In the above-described embodiment, the fly-eye lens 4 having a large number of lens elements 4a arranged in parallel is used. However, without being limited to this, a modified example in which the fly-eye lens 4 and the condenser lens 6 are omitted as shown in FIG. 10 is also possible. In the modification of FIG. 10, as shown in FIG. 11, a plurality of chips 31 a of the LED light source 31 have a rectangular light emitting surface similar to the illumination area on the mask M (and thus similar to the unit exposure area on the substrate W). Having. An aperture stop 32 having a circular opening 32 a is arranged near the front focal position of the relay lens 3, and the pattern surface of the mask M is arranged near the rear focal position of the relay lens 3.

  In the case of a step-and-repeat type exposure apparatus (stepper exposure machine), the field of view of the projection optical system PL is often circular, and the light emitting surface of the chip 31a is square or square inscribed in the circular field of view. It is similar to a close rectangle. In a step-and-scan type exposure apparatus (scanning type exposure apparatus), the field of view of the projection optical system PL is often rectangular, and the light emitting surface of the chip 31a is similar to the rectangular field of view. The light emitting surface of each chip 31a of the LED light source 31 is disposed near the front focal position of the corresponding collector lens 2, and light emitted from one point on the light emitting surface is converted by the collector lens 2 into a substantially parallel light flux. The light beam having passed through each collector lens 2 is applied to the mask M via the aperture stop 32 and the relay lens 3.

  Since the aperture stop 32 is arranged near the rear focal position of the collector lens 2, the set of the chip 31a and the collector lens 2 is positioned inside the circular opening 32a of the aperture stop 32 as shown in FIG. Must be located at FIG. 11 shows an example in which the chip 31a has a rectangular light emitting surface. In the modification of FIG. 10, the angular distribution of the illumination light can be selected by selectively lighting the plurality of chips 31a. As shown in FIG. 11, when all of the chips 31a arranged inside the circular opening 32a of the aperture stop 32 are turned on, almost uniform ordinary illumination (circular illumination) is provided at a predetermined aperture. It can be carried out.

  On the other hand, as shown in FIG. 12, when only the peripheral chip 31a is turned on in an annular shape inside the opening 32a, annular illumination can be performed. In FIG. 12, the lit chips are denoted by reference numeral 31aa, and the lit chips are hatched and denoted by reference numeral 31ab. Actually, by providing a larger number of sets of the chip 31a and the collector lens 2 than in FIGS. 11 and 12, a finer ring-shaped pattern can be formed. Further, by inserting an anamorphic prism between the chip 31a and the collector lens 2 or making the optical surface of the collector lens 2 a toric surface, even if the light emitting surface of the chip 31a is square, the mask M It can be transferred to the upper rectangular illumination area.

  In the present embodiment, the illumination area on the mask can be regarded as an area on a predetermined surface through which the illumination light passes. Since the images of the light emitting surfaces of the respective chips 31a are projected on the predetermined surface so as to substantially overlap each other, the illuminance distribution of the illumination light in the region on the predetermined surface (the illumination region on the mask M) is substantially reduced. Can be uniform.

  In the above-described embodiment, the surface of the chip 1a from which light is emitted is the light emitting surface. However, when a light-shielding member having an opening of a predetermined shape is provided on the upper surface of the chip 1a, the opening emits light. In order to determine the area, the area of the opening may be regarded as the light emitting surface.

  In each of the above-described embodiments, the light from the plurality of light emitting surfaces is condensed by the plurality of collector lenses 2 having optical axes substantially parallel to each other. Need not be parallel to each other. When the optical axes of the plurality of collector lenses 2 are parallel to each other, the degree of superposition of light from the plurality of light-emitting surfaces on a predetermined surface can be increased, but the illuminance distribution on the predetermined surface is not uniform. In this case, the optical axes of the plurality of collector lenses 2 may be non-parallel to each other.

  Further, the optical axes of the plurality of collector lenses 2 may be provided so as to deviate from the center positions of the plurality of light emitting surfaces. Further, the lens in each of the above embodiments is not limited to a single lens, and may be a lens group including a plurality of lenses. The invention is not limited to a refractive optical member such as a lens, and may be a diffractive optical element that diffracts light or a reflective optical element that reflects light. Further, in each of the above-described embodiments, the fly-eye lens 4 has a plurality of lens elements arranged in parallel. However, the fly-eye lens 4 may have a structure in which the plurality of lens elements are provided integrally.

  Further, in each of the embodiments described above, the aperture stop 5 is arranged on the illumination pupil plane, but the aperture stop 5 may be omitted. Further, in the embodiment shown in FIG. 8, a lamp may be used instead of the solid state light emitting device. In this case, an image of the bright spot of the lamp may be formed at the incident end of the optical fiber. Further, the image of the lamp luminescent spot may be formed on the fiber core at the entrance end of the optical fiber.

  The exposure apparatus according to the above-described embodiment is manufactured by assembling various subsystems including the components described in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Is done. Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and various electric systems to ensure these various accuracy Are adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from various subsystems includes mechanical connections, wiring connections of electric circuits, and piping connections of pneumatic circuits among the various subsystems. It goes without saying that there is an assembling process for each subsystem before the assembling process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. The manufacture of the exposure apparatus may be performed in a clean room where the temperature, cleanliness, etc. are controlled.

  Next, a device manufacturing method using the exposure apparatus according to the above-described embodiment will be described. FIG. 13 is a flowchart showing a manufacturing process of the semiconductor device. As shown in FIG. 13, in the semiconductor device manufacturing process, a metal film is deposited on a wafer W serving as a substrate of the semiconductor device (Step S40), and a photoresist as a photosensitive material is applied on the deposited metal film. (Step S42). Subsequently, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W using the projection exposure apparatus of the above-described embodiment (Step S44: exposure step), and the wafer W on which the transfer is completed , That is, development of the photoresist on which the pattern has been transferred (Step S46: development step).

  Thereafter, processing such as etching is performed on the surface of the wafer W using the resist pattern generated on the surface of the wafer W in step S46 as a mask (step S48: processing step). Here, the resist pattern is a photoresist layer in which irregularities having a shape corresponding to the pattern transferred by the projection exposure apparatus of the above-described embodiment are generated, and the concave portions penetrate the photoresist layer. It is. In step S48, the surface of the wafer W is processed through the resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W and deposition of a metal film or the like. In step S44, the projection exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as a photosensitive substrate.

  FIG. 14 is a flowchart showing a process of manufacturing a liquid crystal device such as a liquid crystal display element. As shown in FIG. 14, in the manufacturing process of the liquid crystal device, a pattern forming process (Step S50), a color filter forming process (Step S52), a cell assembling process (Step S54), and a module assembling process (Step S56) are sequentially performed. In the pattern forming step of step S50, predetermined patterns such as a circuit pattern and an electrode pattern are formed on the glass substrate coated with the photoresist as the plate P by using the projection exposure apparatus of the above-described embodiment. The pattern formation step includes an exposure step of transferring a pattern to a photoresist layer using the projection exposure apparatus of the above-described embodiment, and development of the plate P on which the pattern has been transferred, that is, development of the photoresist layer on the glass substrate. To form a photoresist layer having a shape corresponding to the pattern, and a processing step of processing the surface of the glass substrate through the developed photoresist layer.

  In the color filter forming step of step S52, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three R, G, B A color filter is formed by arranging a plurality of sets of striped filters in the horizontal scanning direction. In the cell assembling step of step S54, a liquid crystal panel (liquid crystal cell) is assembled using the glass substrate on which the predetermined pattern has been formed in step S50 and the color filters formed in step S52. Specifically, for example, a liquid crystal panel is formed by injecting a liquid crystal between a glass substrate and a color filter. In the module assembling step of step S56, various components such as an electric circuit and a backlight for performing a display operation of the liquid crystal panel are attached to the liquid crystal panel assembled in step S54.

  Further, the above-described embodiment is not limited to application to an exposure apparatus for manufacturing a semiconductor device. For example, a liquid crystal display element formed on a square glass plate or a sheet-shaped flexible body, or a plasma display And the like, and can be widely applied to an exposure device for manufacturing various devices such as an exposure device for a display device such as an imaging device (CCD or the like), a micro machine, a thin film magnetic head, and a DNA chip. Further, the above-described embodiment can be applied to an exposure step (exposure apparatus) when manufacturing a mask (photomask, reticle, or the like) on which a mask pattern of various devices is formed by using a photolithography step. .

1 LED light source 1a chip (light emitting unit)
2 collector lens 3 relay lens 4 fly-eye lens 4a lens element 5 aperture stop 6 condenser lens IL illumination optical system M mask MS mask stage PL projection optical system W wafer WS wafer stage CR control system

Claims (14)

In an illumination optical system that illuminates an irradiated surface,
A first light emitting unit that emits first illumination light from the first light emitting surface;
A second light-emitting unit that emits second illumination light from a second light-emitting surface disposed at a distance from the first light-emitting surface;
A light-collecting member having a first light-collecting unit that collects the first illumination light from the first light-emitting surface and a second light-collecting unit that collects the second illumination light from the second light-emitting surface;
At least a part of an image of the first light-emitting surface by the first illumination light passing through the first light-collecting unit and an image of the second light-emitting surface by the second illumination light passing through the second light-collecting unit, A relay optical system that is superposed on the illuminated surface or the conjugated surface optically conjugate to the illuminated surface,
An optical integrator having a plurality of wavefront splitting elements arranged in parallel in an optical path between the relay optical system and the irradiated surface,
A condenser optical system that superimposes a plurality of light beams wavefront-divided by the optical integrator on the irradiated surface,
The illumination optical system according to claim 1, wherein the conjugate plane coincides with a plane on the incident side of the plurality of wavefront splitting elements located between the relay optical system and the condenser optical system. The light-collecting member and the relay optical system are configured so that the surfaces on the incident side of the plurality of wavefront splitting elements and the first light-emitting surface and the second light-emitting surface have an optically conjugate relationship with each other. The illumination optical system according to claim 1, wherein the illumination optical system is arranged in an optical path between the first light emitting unit and the second light emitting unit and the optical integrator . The relay optical system is such that the image of the first light emitting surface and the image of the second light emitting surface are larger than the size of a surface on the incident side of one of the plurality of wavefront splitting elements, The illumination optical system according to claim 1, wherein an image of the first light emitting surface and an image of the second light emitting surface are enlarged . 4. A deflecting member arranged so as to be insertable into an optical path between the condensing member and the relay optical system, and changing the angle of incident light to emit the light. or illumination optical system according to item 1. The first light-collecting unit of the light-collecting member has a first lens, the second light-collecting unit of the light-collecting member has a second lens,
The illumination optical system according to any one of claims 1 to 4, wherein an optical axis of the first lens and an optical axis of the second lens are parallel to each other . The first light emitting unit is arranged such that the first light emitting surface is located at a front focal point of the first lens,
The illumination optical system according to claim 5, wherein the second light emitting unit has the second light emitting surface disposed at a position of a front focal point of the second lens . The illumination optical system according to claim 5, wherein the first lens and the second lens are formed integrally . The illumination optical system according to any one of claims 1 to 7, further comprising: a first solid state light emitting device having the first light emitting portion; and a second solid state light emitting device having the second light emitting portion. . The first light emitting unit includes a first light guide for transmitting light from a first light source, the second light emitting unit includes a second light guide for transmitting light from a second light source,
9. The light emitting device according to claim 1, wherein the first light emitting surface is an emission surface of the first light guide, and the second light emitting surface is an emission surface of the second light guide. Illumination optics. The illumination optical system according to claim 1, wherein the first light emitting surface and the second light emitting surface are circular . The illumination optical system according to any one of claims 1 to 10, wherein the first light emitting surface and the second light emitting surface have a shape similar to an illumination region formed on the surface to be irradiated. . 12. An exposure apparatus comprising: the illumination optical system according to claim 1 for illuminating a predetermined pattern provided on the surface to be irradiated, wherein the predetermined pattern is exposed on a substrate. Equipment . 13. The exposure apparatus according to claim 12, further comprising a projection optical system that forms the image of the predetermined pattern on the substrate . Using the exposure apparatus according to claim 12 or 13, exposing the predetermined pattern to the substrate,
Developing the substrate on which the predetermined pattern has been transferred, forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the substrate;
Processing the surface of the substrate via the mask layer .

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