JP6700982B2 - Optical system, exposure apparatus, and article manufacturing method - Google Patents

Description

  The present invention relates to an optical system, an exposure apparatus including the optical system, and an article manufacturing method for manufacturing an article using the exposure apparatus.

  Solid-state light-emitting devices such as LEDs (light-emitting diodes) and LDs (laser diodes) are smaller, consume less energy, and have a longer lifespan than other light-source devices such as ultra-high pressure mercury lamps, so many lighting devices are used. Is being used in. A solid-state light emitting element is a light source element that emits light by supplying energy such as electricity to a solid substance and exciting it.

  However, the solid-state light emitting device has a problem that the emission brightness is smaller than that of the ultra-high pressure mercury lamp. In particular, in an illuminating device incorporated in an exposure apparatus for manufacturing a device such as a semiconductor device, high brightness is required to realize high productivity. Therefore, the low emission brightness is a great obstacle in using the solid-state light emitting element in the exposure apparatus.

  Patent Document 1 describes using a plurality of LED elements in order to obtain high illumination brightness. More specifically, in Patent Document 1, a plurality of LED elements and a light incident surface correspond to each of the plurality of LED elements, and light emitting surfaces are arranged close together, in contact with or integrated with each other. An LED lighting device including a rod assembly which is an assembly of a plurality of formed rods is described.

JP, 2015-88410, A

  Illumination light having high brightness can be obtained by combining the lights generated by the plurality of solid state light emitting devices. However, in the illumination device used in the exposure apparatus, it is necessary to illuminate a desired illumination area on the illuminated surface with a desired incident angle distribution. On the other hand, Helmholtz-Lagrange invariants can only be conserved or large. According to this principle, only the light generated by the light source that is smaller than the Helmholtz-Lagrange amount determined by the illumination area of the illuminated surface and the maximum incident angle can reach the illuminated surface. Therefore, it is required to collect the light generated by the light source without increasing the Helmholtz-Lagrange amount.

  However, for example, in the invention described in Patent Document 1, since the rod is arranged so as to be inclined, the angular distribution of the light generated by the solid-state light emitting element is inclined at the exit surface of the rod, and thus the maximum angle of the combined light is increased. However, the angle becomes larger than the angle of light generated by the solid state light emitting device.

  An object of the present invention is to provide an advantageous technique for efficiently guiding light from a plurality of solid state light emitting elements to an illuminated area.

  One aspect of the present invention relates to an optical system, and the optical system includes a first light source unit having a plurality of solid-state light emitting elements arranged at a first pitch along a first direction and the first light source unit facing the light source unit. An optical member having a pair of first reflecting surfaces arranged apart from each other in a direction, and a condensing optical system arranged between the light source unit and the optical member. In the optical system and the optical member, the light generated by each of the plurality of solid state light emitting elements is incident on the incident end of the optical member and emitted from the exit end of the optical member, and each of the plurality of solid state light emitting elements. The images are arranged so as to overlap at the exit end.

  According to the present invention, an advantageous technique is provided for efficiently guiding light from a plurality of solid state light emitting devices to an illuminated region.

The figure which shows the structure of the exposure apparatus of one Embodiment of this invention. The figure which shows the structure of the optical system of one Embodiment of this invention. The figure explaining the principle of one Embodiment of this invention. The figure explaining the principle of one Embodiment of this invention. The figure explaining the principle of one Embodiment of this invention. The figure which shows the light source part and synthetic|combination light source image of one Embodiment of this invention. The figure which illustrates the light source part of other embodiment of this invention. The figure which shows the structure of the optical system of other embodiment of this invention. The figure explaining composition of a plurality of light source images in an optical system of other embodiments of the present invention.

  Hereinafter, the present invention will be described through exemplary embodiments thereof with reference to the accompanying drawings.

  FIG. 1 shows the configuration of an exposure apparatus EX according to an embodiment of the present invention. The exposure apparatus EX projects the illumination optical system 1, the original stage RS holding the original plate 2, the substrate stage SS holding the substrate 4, and the pattern of the original plate 2 onto the substrate 4 coated with a photosensitive material. And a projection optical system 3 for exposing. The illumination optical system 1 includes an optical system OS including a light source unit 001, an optical integrator 15 arranged between an original plate surface RP on which the original plate 2 is arranged and the optical system OS, an optical integrator 15 and an original plate surface RP. And a condenser lens 16 disposed therebetween. Further, the illumination optical system 1 may include the wavelength filter 14 arranged between the optical system OS and the optical integrator 15. Further, the illumination optical system 1 can include a relay optical system 13 arranged between the optical system OS and the optical integrator 15. The relay optical system 13 can have a variable power function, for example. Further, the illumination optical system 1 may have a masking blade 17 and a relay optical system 18 between the condenser lens 16 and the original plate surface RP.

  The optical system OS may include a light source unit 001, an optical member 12, and a condensing optical system 11 arranged between the light source unit 001 and the optical member 12. The light source unit 001 has a plurality of solid state light emitting elements 10. In addition, when distinguishing a plurality of solid-state light emitting elements 10 from each other, a suffix is added to the end of the reference numeral 10 such as 10 a and 10 b for description. The solid state light emitting device 10 may be, for example, an LED (light emitting diode) or an LD (laser diode). The plurality of solid-state light emitting elements 10 are arranged at a first pitch along the X direction (first direction), and the optical members 12 are arranged so as to face each other and are spaced apart in the X direction (first direction). The first reflective surfaces 121 and 122 of The optical member 12 can be, for example, a glass rod or a hollow mirror. The glass rod is a solid rod made of glass, and the light incident on the incident end 004 of the glass rod passes through the glass medium and reaches the emission end 005. In the glass rod, the pair of reflecting surfaces 121, 122 is constituted by a boundary between the glass rod and a medium (for example, air) outside the glass rod. For a glass rod, the index of refraction N described below is the index of refraction of the glass medium. In the hollow mirror, the space between the entrance end 004 and the exit end 005 is a gas such as air or a vacuum, and the pair of reflecting surfaces is configured by a member (mirror) that is in contact with the space. For hollow mirrors, the index of refraction N, described below, is the index of refraction of gas or vacuum. The condensing optical system 11 condenses light from the plurality of solid state light emitting elements 10 of the light source unit 001. In the light source unit 001, the condensing optical system 11, and the optical member 12, the light generated by each of the plurality of solid-state light emitting elements 10 is incident on the incident end of the optical member 12 and emitted from the emitting end of the optical member 12, and The respective images of the solid-state light-emitting element 10 can be arranged so as to overlap at the emission end.

  The light emitted from the optical system OS (emission end 005 of the optical member 12) is projected onto the optical integrator 15 by the relay optical system 13. The wavelength filter 14 transmits only the light of the wavelength used for exposing the substrate 4 among the light from the optical system OS (light source unit 001). The wavelength bandwidth in which the chromatic aberration is favorably corrected by the projection optical system 3 is usually about several tens of nm. Therefore, when the emission spectrum of the solid-state light emitting element 10 of the light source unit 001 has a wide band, the wavelength filter 14 narrows the light. In addition, the emission spectrum of the solid-state light-emitting element 10 may change due to environmental changes due to temperature or the like and the time of use. Even in such a case, good imaging performance can be obtained by extracting only a desired wavelength band by the wavelength filter 14. The wavelength filter 14 may include a plurality of filters, and in this case, a filter corresponding to the required imaging performance may be selected and used from the plurality of filters. For example, when forming a pattern with a thick line width, by using a filter with a wide transmission wavelength band, high illuminance can be realized and productivity can be improved. On the other hand, when forming a pattern with a narrow line width, the amount of chromatic aberration generated in the projection optical system 3 can be reduced by using a filter having a narrow transmission wavelength band.

  The optical integrator 15 can be composed of, for example, a fly-eye lens. The optical integrator 15 splits the light from the light source unit 001 into wavefronts, and forms a plurality of secondary light sources on the exit surface of the optical integrator 15. The optical integrator 15 can be composed of, for example, an assembly of a plurality of rod lenses, an assembly of a plurality of strip-shaped cylindrical lenses, or a microlens array. The condenser lens 16 forms a uniform light intensity distribution on the surface on which the masking blade 17 is arranged by superimposing light from a plurality of secondary light sources formed on the exit surface of the optical integrator 15 in a superimposed manner. The relay optical system 18 makes an optically conjugate relationship between the surface on which the masking blade 17 is arranged and the original surface RP on which the original 2 is arranged.

  A half mirror 19 may be arranged in the optical path of the illumination optical system 1. The half mirror 19 splits a part of the light in the optical path toward the sensor 20. The sensor 20 can be used to monitor the amount of light during exposure of the substrate 4. For example, the exposure amount of the substrate 4 can be controlled based on the value detected by the sensor 20. For example, when the exposure apparatus EX is a step-and-repeat type, the light source unit 001 (a plurality of solid-state light emitting elements 10) is turned on at the time of starting the exposure of the substrate 4, and then the light amount is integrated by the sensor 20, and the integrated value is the target. The light source unit 001 is turned off at the timing when the exposure amount is reached. When there is a time delay in the turning-off control, the turning-off control of the light source unit 001 may be started when the integrated value reaches a value smaller than the target exposure amount by the time delay. Further, the exposure amount control may be performed using a shutter. In this case, the exposure amount can be controlled by opening and closing the shutter (not shown) with the light source unit 001 (solid-state light emitting element 10) turned on. When the exposure apparatus EX is a scanning type exposure apparatus (step-and-scan method), the electric power supplied to the plurality of solid state light emitting elements 10 of the light source unit is controlled so that the measurement value by the sensor 20 becomes constant. sell. When the target exposure amount is small and exposure cannot be performed at the maximum scanning speed, some of the plurality of solid state light emitting elements 10 are turned off or the power supplied to the plurality of solid state light emitting elements 10 is reduced. The exposure amount can be adjusted by

  Hereinafter, the configuration of the optical system OS will be exemplarily described with reference to FIG. The plurality of solid-state light emitting elements 10 forming the light source unit 001 are arranged at the first pitch L1 along the X direction (first direction). In FIG. 2, two solid-state light emitting devices 10 are shown as 10a and 10b for simplification. The pitch means the arrangement period of the plurality of solid state light emitting elements 10, and for example, the center-to-center distances of adjacent solid state light emitting elements 10 are equal. Within the light distribution of each solid-state light emitting element 10, the range of the light distribution in which light is to be taken in by the optical member 12 is ±θ. That is, it is assumed that light within the angle range of ±θ with respect to the normal to the surface of the solid-state light-emitting element 10 (range between −θ and +θ) is taken in by the optical member 12.

  The condensing optical system 11 is indicated by an up-down arrow. The focal length of the condensing optical system 11 is f. The pupil plane of the condensing optical system 11 is arranged at a distance of f+a from the light emitting surface of the light source unit 001 (the light emitting surfaces of the plurality of solid state light emitting elements 10). The light emitting surface means a surface from which light is emitted. The light generated by each of the plurality of solid state light emitting devices 10 of the light source unit 001 enters the entrance end 004 of the optical member 12 and exits from the exit end 005 of the optical member 12. The light source unit 001, the condensing optical system 11, and the optical member 12 are arranged such that the exit end 005 of the optical member 12 is conjugate with the light emitting surface of the light source unit 001 (the light emitting surface of the plurality of solid state light emitting elements 10). Expressed from another viewpoint, the light source unit 001, the condensing optical system 11, and the optical member 12 can be arranged so that the images of the plurality of solid-state light-emitting elements 10 overlap at the exit end 005 of the optical member 12.

  Hereinafter, a preferable relationship among the distance a, the focal length f, the length of the optical member 12, and the distance D between the pair of reflecting surfaces 121 and 122 of the optical member 12 will be described with reference to FIGS. However, the relationship described here is an ideal relationship, and in an actual optical system OS, there is an error within a range that satisfies the required specifications with respect to such an ideal relationship, or It is permissible to make corrections according to the restrictions, etc.

  The light beam emitted from the solid-state light emitting element 10a existing on the optical axis of the condensing optical system 11 is condensed at a point 005a on the emission end 005 of the optical member 12 as shown in FIG. Assuming that the refractive index of the optical member 12 (refractive index of a portion through which a light ray passes) is N and the length of the optical member 12 in the optical axis direction is M, the light emitting surface of the light source unit 001 and the front focus of the condensing optical system 11 are defined. The distance a and the focal length f of the condensing optical system 11 have a relationship of M/N=f×f/a.

  As shown in FIG. 4, the distance D between the pair of reflecting surfaces 121 and 122 of the optical member 12 forms an image of the solid-state light-emitting element 10b adjacent to the solid-state light-emitting element 10a at a point 005a of the exit end 005 of the optical member 12. It is decided to be done. That is, the spacing D is determined so that the magnification β=f÷a of the condensing optical system 11, the pitch L1 of the adjacent solid state light emitting devices 10a and 10b, and the spacing D1 satisfy the relationship of D1=β×L1. . At this time, as shown in FIG. 4, the light beams emitted from the solid-state light emitting elements 10a and 10b arranged at the pitch L1 are focused on one point 005a. That is, the centers of the respective images of the solid state light emitting devices 10a and 10b arranged at the pitch L overlap at one point 005a.

  With the above arrangement, as illustrated in FIG. 5, light rays emitted from all the solid state light emitting elements 10 (10a, 10b, 10c) arranged at the pitch L1 along the X direction (first direction). Overlap at one point 005a of the exit end 005 of the optical member 12.

  Further, in order to capture the light in the ±θ angle range of the light distribution of the solid-state light emitting element 10 at the incident end 004 of the optical member 12, it is necessary to satisfy f×sin θ=D1/2.

  To summarize the above, it is preferable that the condition represented by the following formula is satisfied.

D1=β×L1
D1=2×f×sin θ
a=f×L1÷D1=L1÷(2×sin θ)
M=2×(sin θ)×N×f×f÷L1
According to the above configuration, the light source images of the plurality of solid state light emitting elements 10 are combined at the exit end 005 of the optical member 12 to form a combined light source image. The combined light source image may be formed on a part of the exit end 005 of the optical member 12 instead of the entire area.

  The above principle is also applied to the case of using the light source unit 001 including a plurality of solid state light emitting elements 10 arranged so as to form a two-dimensional array. In FIG. 6A, a plurality of plural pitches are provided so as to have a first pitch L1 in the X direction (first direction) and a second pitch L2 (=L1) in the Y direction (second direction) orthogonal to the X direction. Illustrated is a light source section 001 configured by arranging the solid-state light emitting element 10 of FIG. Each solid-state light emitting element 10 has a light emitting region 101. The plurality of light emitting regions 101 are arranged so as to have a first pitch L1 in the X direction (first direction) and a second pitch L2 in the Y direction (second direction). In this example, the first pitch L1 and the second pitch L2 are equal. That is, L1=L2.

  The optical member 12 is illustrated in FIG. The optical member 12 is spaced apart from each other in the X direction (first direction) so as to face each other, and is separated from each other in the Y direction (second direction) so as to face each other. And a pair of second reflecting surfaces 123 and 124 that are arranged in parallel. The distance between the pair of first reflecting surfaces 121 and 122 is D1, and the distance between the pair of first reflecting surfaces 121 and 122 is D2, but D2 is equal to D1. At the exit end of the optical member 12, a combined light source image LSI is formed in which the respective light source images (images of the light emitting regions 101) of the plurality of solid state light emitting elements 10 arranged to form a two-dimensional array are combined. . An outer portion of the combined light source image LSI corresponds to a portion between adjacent light emitting areas 101 (a portion where the light intensity is 0).

  The relay optical system 13 uses the combined light source image LSI as a light source. As a result, it is possible to eliminate an increase in the Helmholtz-Lagrange invariant due to the gap between the light emitting regions 101 of the solid-state light-emitting element 10, and it is possible to efficiently guide the light from the plurality of solid-state light-emitting elements 10 to the illuminated area. .

  In one example, when the angle range of ±60 degrees of the light distribution of the plurality of solid state light emitting elements 10 arranged with L1=L2=1.2 mm is used, when the condensing optical system 11 with the focal length f=5 mm is used. , A=0.69 mm, the light source unit 001 can be arranged. A glass rod having a width D1, D2=8.7 mm, a length M=54.1 mm and a refractive index N=1.5 may be arranged as the optical member 12.

  The light emitting surface of the light source unit 001, the exit end 0005 of the condensing optical system 11 and the optical member 12 may be arranged such that the light emitting surface of the light source unit 001 and the exit end 005 of the optical member 12 are in a conjugate position. preferable. However, it is permissible that the arrangement has an error according to the required specifications, or that the arrangement is modified according to design restrictions or the like. Here, when the light source unit 001 (solid-state light-emitting element 10) is arranged while being shifted by Δz in the optical axis direction of the condensing optical system 11, the light beam from the solid-state light-emitting element 10 spreads by Δz×tan θ. Here, as described above, θ indicates the range of the light distribution of the solid light emitting element 10 in which the optical member 12 should take in light. If the spread Δz×tan θ of the light rays is sufficiently small with respect to the pitch L1, the performance degradation due to Δz can be allowed. For example, if Δz≦L÷tan θ÷10, generally, the required specifications can be satisfied. That is, the distance between the conjugate surface of the exit end 005 of the optical member 12 defined by the condensing optical system 11 (that is, the surface where the distance from the pupil surface of the condensing optical system 11 is f+a) and the light emitting surface of the light source unit 001. Is preferably within L1/tan θ/10.

  In the example described with reference to FIG. 6, L1=L2. However, the present invention is also applicable when L1 and L2 are different. In FIG. 7, a plurality of solid-state light-emitting devices have a first pitch L1 in the X direction (first direction) and a second pitch L2 (≠L1) in the Y direction (second direction) orthogonal to the X direction. A light source unit 001 configured by arranging the element 10 is illustrated. Each solid-state light emitting element 10 has a light emitting region 101. The plurality of light emitting regions 101 are arranged so as to have a first pitch L1 in the X direction (first direction) and a second pitch L2 in the Y direction (second direction) orthogonal to the X direction. In this example, the first pitch L1 and the second pitch L2 are different. That is, L1≠L2.

  FIG. 8 shows the arrangement of the light source unit 001, the condensing optical system 11, and the optical member 12. The optical member 12 is spaced apart from each other in the X direction (first direction) so as to face each other, and is separated from each other in the Y direction (second direction) so as to face each other. And a pair of second reflecting surfaces 123 and 124 that are arranged in parallel. The distance between the pair of first reflecting surfaces 121 and 122 is D1, the distance between the pair of second reflecting surfaces 123 and 124 is D2, and D2 is different from D1.

  The distance between the light emitting surface of the light source unit 001 (the light emitting surfaces of the plurality of solid state light emitting elements 10) and the condensing optical system 11 is f+a, and the focal length of the condensing optical system 11 is f. Of the light distribution distribution in the X direction of each solid-state light-emitting element 10, the angle range of the light distribution distribution for taking in light by the optical member 12 is ±θ1, and the light distribution distribution in the Y-direction of each solid-state light-emitting element 10 is determined by the optical member 12. The angle range of the light distribution for capturing light is ±θ2. Further, the refractive index of the optical member 12 (the refractive index of the portion through which the light ray passes) is N, and the length of the optical member 12 in the optical axis direction is M. In this definition, it is preferable to satisfy the condition shown by the following equation based on the same idea as above.

D1=β×L1
D2=β×L2
D1=2×f×sin θ1
D2=2×f×sin θ2
a=f×L1÷D1=L1÷(2×sin θ1)
a=f×L2÷D2=L2÷(2×sin θ2)
M=2×(sin θ1)×N×f×f÷L1
M=2×(sin θ2)×N×f×f÷L2
By satisfying the above conditions, even when a plurality of solid state light emitting elements 10 are arranged at mutually different pitches in the X and Y directions as shown in FIG. 9, light source images of the plurality of solid state light emitting elements 10 are obtained. Are combined at the exit end 005 of the optical member 12 to form a combined light source image. Even in such a configuration, the conjugate surface of the exit end 005 of the optical member 12 defined by the condensing optical system 11 (that is, the surface at a distance f+a from the pupil plane of the condensing optical system 11) and the light source unit 001. The distance to the light emitting surface is
It is preferable to satisfy the conditions of L1÷tan θ1/10 and L2÷tan θ2/10.

  Hereinafter, a method for manufacturing an article using the above exposure apparatus will be described. The article manufacturing method may include a coating step, an exposure device, a developing step, and a processing step. In the coating process, a photoresist is coated on the substrate. In the exposure process, the photoresist on the substrate that has been subjected to the coating process can be exposed by the exposure device. In the developing process, the photoresist on the substrate that has undergone the exposing process may be developed to form a resist pattern. In the processing step, the substrate that has undergone the developing step can be processed. This treatment may include, for example, etching, ion implantation or oxidation.

1: Illumination optical system, 2: Original plate, 3: Projection optical system, 4: Substrate, OS: Optical system, 001: Light source part, 10: Solid state light emitting element, 11: Condensing optical system, 12: Optical member, 121 to 121 Reference numeral 124: reflective surface, 13: relay optical system, 14 wavelength filter, 15: optical integrator, 16: condenser lens, 17: masking blade, 18: relay optical system, 004: incident end, 005: exit end, L1, L2: pitch

Claims (12)

A light source section having a plurality of solid state light emitting elements arranged at a first pitch along a first direction;
An optical member having a pair of first reflecting surfaces which are arranged to be separated from each other in the first direction so as to face each other;
A condensing optical system disposed between the light source unit and the optical member,
In the light source unit, the condensing optical system, and the optical member, the light generated by each of the plurality of solid-state light emitting elements is incident on the incident end of the optical member and emitted from the emission end of the optical member, and The respective images of the solid-state light-emitting elements of are arranged so as to overlap at the exit end,
An optical system characterized by that. When the first pitch is L1 and the range of the light distribution for capturing light by the optical member in the light distribution of each solid-state light emitting element is ±θ, the exit end defined by the condensing optical system The distance between the conjugate surface of the above and the light emitting surface of the light source unit is within L1÷tan θ/10.
The optical system according to claim 1, wherein: When the magnification of the condensing optical system is β and the distance between the pair of first reflecting surfaces is D1, D1=β×L1 is satisfied,
The optical system according to claim 2, wherein: The plurality of solid state light emitting devices are arranged so as to form a two-dimensional array, the two-dimensional array having the first pitch in the first direction and a second direction in a second direction orthogonal to the first direction. Has 2 pitches,
The optical member further has a pair of second reflecting surfaces that are spaced apart in the second direction so as to face each other.
The optical system according to claim 1, wherein: The first pitch is L1, the second pitch is L2, and the range of the light distribution in which light is to be captured by the optical member in the light distribution of each solid light emitting element in the first direction is ±θ1, and each solid light emitting element is Of the light distribution in the second direction, where ±θ2 is the range of the light distribution in which light is to be captured by the optical member, the conjugate plane of the exit end defined by the condensing optical system and the light source. The distance from the light emitting surface of the part is within L1÷tan θ1/10 and within L2÷tan θ2/10.
The optical system according to claim 4, wherein: When the magnification of the condensing optical system is β, the distance between the pair of first reflecting surfaces is D1, and the distance between the pair of second reflecting surfaces is D2, D1=β×L1 and D2=β× Satisfy L2,
The optical system according to claim 5, wherein: L1 and L2 are equal,
The optical system according to claim 5 or 6, characterized in that. L1 and L2 are different,
The optical system according to claim 5 or 6, characterized in that. The plurality of solid state light emitting devices are LEDs,
The optical system according to any one of claims 1 to 8, wherein: The optical member is a glass rod or a hollow mirror,
The optical system according to any one of claims 1 to 9, wherein: An exposure apparatus comprising an illumination optical system for illuminating an original plate and a projection optical system for projecting a pattern of the original plate onto a substrate,
The illumination optical system is an optical system according to any one of claims 1 to 10, an optical integrator arranged between an original plate surface on which the original plate is arranged and the optical system, and the optical integrator. Including a condenser lens disposed between the original plate surface,
An exposure apparatus characterized by the above. A coating step of coating a photoresist on the substrate,
An exposure step of exposing the photoresist on the substrate that has undergone the coating step by the exposure apparatus according to claim 11.
A developing step of developing the photoresist on the substrate that has undergone the exposing step to form a resist pattern,
A processing step of processing the substrate that has undergone the developing step,
A method for manufacturing an article, comprising:

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