JP2014195048A - Illumination optical system, exposure equipment, and method of manufacturing device - Google Patents

Abstract

Provided is an illumination optical system that is advantageous for efficiently illuminating a surface to be illuminated using light from a plurality of light sources.
An illumination optical system that illuminates a surface to be illuminated with light from a plurality of light sources, the plurality of optical systems arranged corresponding to each of the plurality of light sources, and the plurality of optical systems A combination system that guides light from each of the light to a conjugate surface optically conjugate with the illuminated surface, and an illumination system disposed between the conjugate surface and the illuminated surface, For each of a plurality of illumination areas formed on the conjugate plane by light from each of the plurality of light sources via the optical system and the synthesis system, the area has a non-circular shape, and the conjugate plane The plurality of optical systems and the synthesis system are configured so that they fall within the effective area of the optical system, and the effective system captures light for illumination of the illuminated surface of the conjugate plane area. Illumination characterized in that To provide the academic system.
[Selection] Figure 1

Description

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

  In a lithography process, which is a manufacturing process for semiconductor devices, liquid crystal display devices, etc., a mask (reticle) pattern is transferred via a projection optical system to a substrate (a wafer or glass plate with a resist (photosensitive agent) layer formed on the surface). An exposure apparatus that transfers to the surface is used.

  For example, in a lithography process of a liquid crystal display device, an exposure apparatus that collectively exposes a pattern having a larger area on a mask onto a substrate is required. In order to meet such a demand, a step-and-scan type scanning exposure apparatus capable of obtaining a high resolution and exposing a large screen has been proposed. The scanning exposure apparatus transfers a pattern illuminated with slit-shaped light (slit light) onto a substrate while scanning (scanning) the mask and the substrate via a projection optical system. In the scanning exposure system, in order to improve productivity, technologies to increase the energy (illuminance) of the light that illuminates the mask, such as increasing the power of the light source or using multiple light sources, are proposed. (See Patent Documents 1 and 2).

  For example, the power of the light source is 1 kW to several kW, and in recent years, an ultra-high pressure mercury lamp of 10 kW or more may be used. However, an increase in the power of the light source causes an increase in the running power of the exposure apparatus. Further, since the effect of improving the illuminance on the mask is not proportional to the increase in power, further increase in power is not realistic.

  Patent Document 1 discloses an illumination optical system in which light from three light sources is incident adjacently and combined to form an image. On the other hand, Patent Document 2 discloses an illumination optical system in which the energy density of light per unit area is improved. Such an illumination optical system includes an elliptical mirror for condensing a part of the light from the light source at a position different from the light source, and a spherical mirror for returning a part of the light from the light source to the light source.

JP 2001-326171 A International Publication No. 04/092823

  However, for example, when an illumination optical system that uniformly illuminates a rectangular region is considered, when the technique disclosed in Patent Document 1 is adopted, a plurality of light sources, here, a first light source, Light from the two light sources and the third light source cannot be taken in efficiently. In FIG. 10, a rectangular area indicated by a dotted line is a light capturing area defined by a plane conjugate with the surface to be illuminated. Light incident on a region other than the rectangular region cannot be used in an optical system subsequent to the surface to be illuminated. In other words, in order to improve the light efficiency, it is necessary to configure the illumination optical system so that the light from each light source falls within the rectangular area. However, if the light from each light source overlaps, as shown in FIG. 10, the light from each light source protrudes from the rectangular area (that is, a loss occurs), so that the light from the light source can be used efficiently. Can not.

  Patent Document 2 discloses a technique for matching the optical axis between each light source and the combined surface where the light from each light source is combined with the optical axis after the combined surface. However, the technique disclosed in Patent Document 2 is valid if the number of light sources is two. However, if the number is three or more, light is scattered near the synthesis surface. The light cannot be efficiently guided to the optical system.

  The present invention has been made in view of such a problem of the prior art, and an exemplary object thereof is to provide an illumination optical system that is advantageous for efficiently illuminating a surface to be illuminated using light from a plurality of light sources. To do.

  In order to achieve the above object, an illumination optical system according to one aspect of the present invention is an illumination optical system that illuminates a surface to be illuminated using light from a plurality of light sources, and corresponds to each of the plurality of light sources. A plurality of optical systems arranged in such a manner, a synthesis system for guiding light from each of the plurality of optical systems to a conjugate plane optically conjugate with the illuminated surface, and the conjugate plane and the illuminated surface. Each of a plurality of illumination regions formed on the conjugate plane by light from each of the plurality of light sources via the plurality of optical systems and the synthesis system, The plurality of optical systems and the synthesis system are configured such that the region has a non-circular shape and fits in the effective region in the conjugate plane, and the effective region is the region of the conjugate plane. The illumination system emits light to illuminate the surface to be illuminated. Characterized in that it is a region capable Komu Ri.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, it is possible to provide an illumination optical system that is advantageous for efficiently illuminating a surface to be illuminated using light from a plurality of light sources.

It is the schematic which shows the structure of the illumination optical system in the 1st Embodiment of this invention. It is the schematic which shows the structure of the Dove prism of the illumination optical system shown in FIG. It is the schematic which shows the structure of the fly eye optical system of the illumination optical system shown in FIG. It is the schematic which shows the structure of the slit of the illumination optical system shown in FIG. It is a figure which shows an example of the illumination area | region formed in a synthetic | combination surface by the illumination optical system shown in FIG. It is the schematic which shows the structure of the illumination optical system in the 2nd Embodiment of this invention. It is the schematic which shows the structure of the illumination optical system in the 2nd Embodiment of this invention. It is a figure which shows an example of the illumination area | region formed in a synthetic | combination surface by the illumination optical system shown in FIG. It is the schematic which shows the structure of the exposure apparatus in the 3rd Embodiment of this invention. It is a figure for demonstrating taking-in of the light from a several light source. It is a figure which shows typically the structure of exposure apparatus. It is a figure for demonstrating the amount of Helmholtz Lagrange.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is a schematic diagram showing a configuration of an illumination optical system 100 according to the first embodiment of the present invention. The illumination optical system 100 is an optical system that illuminates a surface to be illuminated using light from a plurality of light sources. The illumination optical system 100 is applied to, for example, an exposure apparatus, and is suitable as an illumination optical system that guides light from a light source to a mask (illuminated surface) on which a pattern to be transferred to a substrate is formed.

  In this embodiment, the illumination optical system 100 illuminates the mask M with light from the first light source 101A, the second light source 101B, and the third light source 101C. However, the illumination optical system 100 may illuminate the mask M with light from two light sources, or illuminate the mask M with light from three or more light sources. The first light source 101A, the second light source 101B, and the third light source 101C are configured by high-pressure mercury lamps in the present embodiment, but may be configured by xenon lamps, excimer lasers, or the like. The illumination optical system 100 includes optical systems 120A, 120B, and 120C, a deflection mirror 107, a second optical system 140, a fly-eye optical system 109, a third optical system 150, a slit 111, and a fourth optical system 160. And have.

  The optical systems 120A, 120B, and 120C are arranged corresponding to the first light source 101A, the second light source 101B, and the third light source 101C, respectively, and the elliptical mirror 102, the spherical mirror 103, the first optical system 105, and the double light source. A prism 106.

  The elliptical mirror 102 is a condensing optical system that condenses light from a corresponding light source among the first light source 101A, the second light source 101B, and the third light source 101C. The elliptical mirror 102 has a shape corresponding to a part of the ellipse, and is arranged such that the position of one of the two focal points of the ellipse matches the position of the corresponding light source. The spherical mirror 103 is arranged so that the position of the center of curvature coincides with the position of the corresponding light source.

  The light emitted from the corresponding one of the first light source 101A, the second light source 101B, and the third light source 101C and reflected by the elliptical mirror 102 is the position of the other focal point of the two focal points of the ellipse, that is, the collected light. Condensed to the light spot 104. The light emitted from the corresponding light source among the first light source 101A, the second light source 101B, and the third light source 101C and reflected by the spherical mirror 103 is condensed at the position of the corresponding light source. Therefore, the light reflected by the spherical mirror 103 passes through the position of the corresponding light source, and is condensed on the condensing point 104 via the elliptical mirror 102.

  The light that has passed through the condensing point 104 is guided to the Dove prism 106 via the first optical system 105. As shown in FIG. 2, the dove prism 106 has a function of rotating an incident light image. For example, when the Dove prism 106 is rotated by θ [degree] about the optical axis AX, the incident light image can be rotated by 2 θ [degree]. Therefore, by rotating the dove prism 106, the illumination area formed on the composite surface 108 described later can be rotated.

  The light that has passed through the dove prism 106 is guided to the synthesis surface 108. Here, the composite surface 108 is a conjugate surface that is optically conjugate with the mask M that is the surface to be illuminated. The composite surface 108 defines an effective region that is a region in which the subsequent illumination system can capture light for illumination of the mask M that is the surface to be illuminated. The latter illumination system is an optical system disposed between the synthesis surface 108 and the mask M, that is, the second optical system 140, the fly-eye optical system 109, the third optical system 150, the slit 111, and the fourth. This is an optical system composed of the optical system 160.

  In the present embodiment, the deflection mirror 107 is disposed between the optical system 120A and the combining surface 108, and between the optical system 120C and the combining surface 108. The deflecting mirror 107 functions as a combining system that guides the light emitted from each of the first light source 101A, the second light source 101B, and the third light source 101C and passed through each of the optical systems 120A, 120B, and 120C to the combining surface 108. The deflecting mirror 107 is an optical member including a reflecting surface that reflects light from each light source, and the reflecting surface is disposed so as to form an illumination area on the combining surface 108. The arrangement relationship and the number of the deflection mirror 107 and the dove prism 106 differ depending on the number of light sources, but the essential effects of the present invention are not changed.

  The first optical system 105 is arranged so that the combining surface 108 is substantially a Fourier transform surface of the condensing point 104. Light from the combining surface 108 is guided to the fly-eye optical system 109 via the second optical system 140. The second optical system 140 is arranged such that the incident surface of the fly-eye optical system 109 is substantially the Fourier transform surface of the combining surface 108.

  FIG. 3 is a schematic diagram showing the configuration of the fly-eye optical system 109. The fly's eye optical system 109 is composed of two lens groups 130 and 131, as shown in FIG. Each of the lens groups 130 and 131 includes a large number of plano-convex lenses arranged in a plane. The lens groups 130 and 131 are arranged with their curvature surfaces facing each other so that a pair of plano-convex lenses are located at the focal positions of the plano-convex lenses constituting each of the lens groups 130 and 131. Therefore, many secondary light source distributions equivalent to the first light source 101A, the second light source 101B, and the third light source 101C are formed on the exit surface 110 of the fly-eye optical system 109.

  Light emitted from the exit surface 110 of the fly-eye optical system 109 is guided to the slit 111 via the third optical system 150. The third optical system 150 is disposed so that the slit 111 is substantially a Fourier transform surface of the exit surface 110 of the fly-eye optical system 109. Since many secondary light source distributions are formed at the position of the exit surface 110 of the fly-eye optical system 109, a uniform light intensity distribution is formed in the slit 111.

  FIG. 4 is a schematic diagram showing the configuration of the slit 111. As shown in FIG. 4, the slit 111 has an arc-shaped opening 23 and blocks light incident on a region other than the opening 23. The arc-shaped light that has passed through the slit 111 (the opening 23 thereof) illuminates the mask M uniformly through the fourth optical system 160.

  In the illumination optical system 100, each of the illumination regions formed on the combining surface 108 by the light from each of the first light source 101A, the second light source 101B, and the third light source 101C via the optical systems 120A to 120C and the deflection mirror 107 is provided. , Having a rotationally asymmetric shape. Here, the rotationally asymmetric shape includes a non-circular shape. Further, the optical systems 120A to 120C and the deflecting mirror 107 are configured so that each of the illumination areas formed on the synthesis surface 108 falls within the effective area of the synthesis surface 108. Specifically, the optical systems 120A to 120C and the deflection mirror 107 are configured so that 95% or more of each illumination area formed on the synthesis surface 108 is within the effective area of the synthesis surface 108. . Therefore, the illumination optical system 100 of the present embodiment efficiently synthesizes the light from each of the first light source 101A, the second light source 101B, and the third light source 101C on the synthesis surface 108 (that is, without being shielded), The mask M, which is the surface to be illuminated, can be efficiently illuminated.

  Hereinafter, a suitable design example of the illumination optical system 100 in the first embodiment will be specifically described.

(Design example 1)
As described above, the illumination optical system 100 illuminates the mask M, which is the illuminated surface, using light from the three light sources, the first light source, the second light source, and the third light source. FIG. 5 shows the first illumination region (light amount distribution) 31, the second illumination region 32, and the third illumination region 33 formed on the synthesis surface 108 by the light from each of the first light source, the second light source, and the third light source. . In addition, the effective area 30 on the composite surface 108 is assumed to have a rectangular shape.

  As shown in FIG. 5, the 1st illumination area 31, the 2nd illumination area 32, and the 3rd illumination area 33 have a rotationally asymmetric shape prescribed | regulated by a string and an arc. In FIG. 5, 34 represents the optical axis of the first light source (the principal ray of light from the first light source), 35 represents the optical axis of the second light source (the principal ray of light from the second light source), and 36 The optical axis of the third light source (principal ray of light from the third light source) is represented, and 37 represents the optical axis of the subsequent illumination system. Note that the principal ray may be slightly tilted from the optical axis due to the aberration of the optical system. However, in the following description, this effect is not considered when the optical axis is expressed as a chief ray.

Consider arranging the first illumination region 31, the second illumination region 32, and the third illumination region 33 so as to fit in the effective region 30. In this case, as shown in FIG. 5, the arrangement relationship of the first illumination region 31, the second illumination region 32, and the third illumination region 33 satisfies the following conditions (1), (2), and (3): It is necessary to configure the optical systems 120A to 120C and the deflection mirror 107.
Condition (1): The string of the second illumination area 32 is parallel to one side 30 a of the effective area 30.
Condition (2): The second illumination region 32 is arranged between the strings of the first illumination region 31 and the strings of the third illumination region 33.
Condition (3): The string of the first illumination area 31 or its extension line and the string of the third illumination area 33 or its extension line intersect with one side 30 a of the effective area 30.

  In this case, the optical axes 34, 35, 36 and 37 are parallel to each other, but are not located on the same plane. For example, a plane 38 including the optical axis 34 and the optical axis 37, a plane 39 including the optical axis 35 and the optical axis 37, and a plane 40 including the optical axis 36 and the optical axis 37 are different planes. In other words, the optical axes 34, 35, 36, and 37 do not exist on the same straight line in the synthesis surface 108.

  As described above, the illumination area on the synthesis surface 108 has a rotationally asymmetric shape, and is a surface orthogonal to the synthesis surface 108, and illumination with at least one of the optical axes of each light source (the optical axis 34, 35, or 36). The illumination optical system is configured so that there are a plurality of surfaces including the optical axis (optical axis 37) of the system. Thereby, since the illumination area formed by the light from each light source can be stored in the effective area 30 without blocking the light from each light source, the light from each light source is efficiently synthesized by the synthesis surface 108. be able to.

  In this embodiment, the shape of all the illumination areas is a non-circular shape and is arranged so as to be within the effective area. However, the shape of the illumination areas of some light sources may be non-circular. For example, the illumination areas from the first light source and the third light source have a non-circular shape like the first illumination area 31 and the third illumination area 33 described above, and the illumination area from the second light source is shown in FIG. Thus, it can be a circular shape. Even if the illumination region from the second light source does not fit in the capture region, the illumination regions from the first light source and the third light source are arranged so as to fit in the capture region, so that three light sources than the state shown in FIG. Can be used effectively. As described above, the light from the light sources can be used effectively by forming a part of the illumination area of the light from the plurality of light sources into a non-circular shape.

<Second Embodiment>
6 and 7 are schematic views showing the configuration of the illumination optical system 200 according to the second embodiment of the present invention. The illumination optical system 200 is an optical system that illuminates a surface to be illuminated with light from a plurality of light sources. The illumination optical system 200 is applied to, for example, an exposure apparatus and is suitable as an illumination optical system that guides light from a light source to a mask (illuminated surface) on which a pattern to be transferred to a substrate is formed.

  In this embodiment, the illumination optical system 200 illuminates the mask M with light from the first light source 101A, the second light source 101B, the third light source 101C, and the fourth light source 101D. The fourth light source 101D is configured by a high-pressure mercury lamp as in the first embodiment, but may be configured by a xenon lamp, an excimer laser, or the like. The illumination optical system 200 includes an optical system 120A, 120B, 120C and 120D, a deflection mirror 107, a second optical system 140, a fly-eye optical system 109, a third optical system 150, a slit 111, and a fourth optical. System 160.

  The optical systems 120A, 120B, 120C, and 120D are disposed corresponding to the first light source 101A, the second light source 101B, the third light source 101C, and the fourth light source 101D, respectively, and the elliptical mirror 102, the spherical mirror 103, 1 optical system 105 and a dove prism 106 are included.

  In the illumination optical system 200, as will be described later, for example, four lights as shown in FIG. 8A are generated by light from each of the first light source 101A, the second light source 101B, the third light source 101C, and the fourth light source 101D. An illumination area is formed on the composite surface 108.

  In the illumination optical system 200, the optical system 120D is configured to be driven in the direction of the arrow shown in FIG. 6 together with the fourth light source 101D. In other words, the illumination optical system 200 has a drive mechanism that drives the optical system 120D in the direction of the arrow shown in FIG.

  FIG. 7 shows a state in which the optical system 120D is driven from the state shown in FIG. 6 to the left side of the drawing. At this time, the Dove prism 106 included in the optical system 120C is rotated about 45 degrees around the optical axis. Further, the light from the second light source 101B is blocked. Specifically, the light emission of the second light source 101B is stopped, or a shutter that blocks light from the second light source 101B is inserted into the optical path of the optical system 120B. At this time, the second light source 101B and the optical system 120B may be driven in a direction perpendicular to the drawing. In FIG. 7, the second light source 101B and the optical system 120B are not shown. In this case, three illumination areas as shown in FIG. 5 are formed on the combining surface 108 by light from each of the first light source 101A, the second light source 101B, and the fourth light source 101D.

  Thus, in the illumination optical system 200, the number of light sources used when illuminating the mask M that is the surface to be illuminated can be changed according to the application. For example, when a large amount of energy is required when illuminating the mask M, the illumination optical system 200 may be brought into the state shown in FIG. On the other hand, when a large amount of energy is not required when illuminating the mask M and it is desired to reduce the running power, the illumination optical system 200 may be brought into the state shown in FIG.

  Hereinafter, a preferred design example of the illumination optical system 200 in the second embodiment and a preferred design example of an illumination optical system using four or more light sources, for example, six light sources will be described in detail.

(Design example 2)
As described above, the illumination optical system 200 illuminates the mask M, which is the surface to be illuminated, using light from the four light sources, the first light source, the second light source, the third light source, and the fourth light source. A first illumination region (light quantity distribution) 41, a second illumination region 42, a third illumination region 43, and a light source formed by the light from each of the first light source, the second light source, the third light source, and the fourth light source; The fourth illumination area 44 is shown in FIG. In addition, the effective area 30 on the composite surface 108 is assumed to have a rectangular shape.

  As shown in FIG. 8A, the first illumination region 41, the second illumination region 42, the third illumination region 43, and the fourth illumination region 44 have a rotationally asymmetric shape defined by a string and an arc. In FIG. 8A, 45 represents the optical axis of the first light source (the principal ray of light from the first light source), and 46 represents the optical axis of the second light source (the principal ray of light from the second light source). ing. 47 represents the optical axis of the third light source (the principal ray of light from the third light source), 48 represents the optical axis of the fourth light source (the principal ray of light from the fourth light source), and 37 represents the latter stage. It represents the optical axis of the illumination system.

Consider arranging the first illumination area 41, the second illumination area 42, the third illumination area 43, and the fourth illumination area 44 so as to fit in the effective area 30. In this case, as shown in FIG. 8A, the arrangement relationship of the first illumination region 41, the second illumination region 42, the third illumination region 43, and the fourth illumination region 44 is as follows: (1) to (5) It is necessary to configure the optical systems 120A to 120D and the deflection mirror 107 so as to satisfy the above.
Condition (1): The string of the second illumination area 42 is parallel to one side 30 a of the effective area 30.
Condition (2): The chord of the third illumination region 43 is parallel to the side 30b facing one side 30a of the effective region 30.
Condition (3): The second illumination region 42 and the third illumination region 43 are arranged between the strings of the first illumination region 41 and the strings of the fourth illumination region 44.
Condition (4): The string of the first illumination area 41 or its extension line and the string of the fourth illumination area 44 or its extension line intersect with one side 30 a of the effective area 30.

  In this case, the optical axes 45, 46, 47, 48 and 37 are parallel to each other, but are not located on the same plane. For example, the plane 49 including the optical axis 45, the optical axis 48, and the optical axis 37 and the plane 50 including the optical axis 46, the optical axis 47, and the optical axis 37 are different planes. In other words, the optical axes 45, 46, 47, 48, and 37 do not exist on the same straight line in the synthesis surface 108.

  As described above, the illumination area on the synthesis surface 108 has a rotationally asymmetric shape and is a surface orthogonal to the synthesis surface 108, and at least one of the optical axes of each light source (optical axis 45, 46, 47, or 48). The illumination optical system is configured so that there are a plurality of surfaces including the optical axis of the illumination system (optical axis 37). Thereby, since the illumination area formed by the light from each light source can be stored in the effective area 30 without blocking the light from each light source, the light from each light source is efficiently synthesized by the synthesis surface 108. be able to.

(Design example 3)
Consider an illumination optical system that illuminates a mask M, which is an illuminated surface, using light from six light sources: a first light source, a second light source, a third light source, a fourth light source, a fifth light source, and a sixth light source. A first illumination area 61, a second illumination area 62, and a third illumination area formed on the synthesis surface 108 by light from each of the first light source, the second light source, the third light source, the fourth light source, the fifth light source, and the sixth light source. An illumination area 63, a fourth illumination area 64, a fifth illumination area 65, and a sixth illumination area 66 are shown in FIG. In addition, the effective area 30 on the composite surface 108 is assumed to have a rectangular shape.

  As shown in FIG. 8B, the first illumination area 61, the second illumination area 62, the third illumination area 63, the fourth illumination area 64, the fifth illumination area 65, and the sixth illumination area 66 are composed of strings and arcs. And a rotationally asymmetric shape defined by In FIG. 8B, 67 represents the optical axis of the first light source (the principal ray of light from the first light source), and 68 represents the optical axis of the second light source (the principal ray of light from the second light source). 69 represents the optical axis of the third light source (the principal ray of light from the third light source). 70 represents the optical axis of the fourth light source (the principal ray of light from the fourth light source), 71 represents the optical axis of the fifth light source (the principal ray of light from the fifth light source), and 72 represents the sixth. This represents the optical axis of the light source (the principal ray of light from the sixth light source), and 37 represents the optical axis of the subsequent illumination system.

Consider arranging the first illumination area 61, the second illumination area 62, the third illumination area 63, the fourth illumination area 64, the fifth illumination area 65, and the sixth illumination area 66 so as to fit in the effective area 30. In this case, as shown in FIG. 8B, the first illumination area 61, the second illumination area 62, the third illumination area 63, the fourth illumination area 64, the fifth illumination area 65, and the sixth illumination area 66 are arranged. The relationship needs to satisfy the following conditions (1) to (4).
Condition (1): The strings of the second illumination area 62 and the strings of the fourth illumination area 64 are parallel to one side 30 a of the effective area 30.
Condition (2): The strings of the third illumination area 63 and the strings of the fifth illumination area 65 are parallel to the side 30 b facing one side 30 a of the effective area 30.
Condition (3): The string of the first illumination region 61 is parallel to the side 30c orthogonal to the sides 30a and 30b of the effective region 30.
Condition (4): The string of the sixth illumination region 66 is parallel to the side 30d facing the side 30c of the effective region 30.

  In this case, the optical axes 67, 68, 69, 70, 71, 72 and 37 are parallel to each other but are not located on the same plane. For example, the plane 73 including the optical axis 67, the optical axis 72, and the optical axis 37, the optical axis 68, the plane 74 including the optical axis 71, and the optical axis 37, the optical axis 69, and the optical axis 70. And the plane 75 including the optical axis 37 are different planes. In other words, the optical axes 67, 68, 69, 70, 71, 72, and 37 do not exist on the same straight line on the composite surface 108.

  As described above, the illumination area on the synthesis surface 108 has a rotationally asymmetric shape, and is a surface orthogonal to the synthesis surface 108, and includes a plurality of surfaces including at least one of the optical axes of each light source and the optical axis of the illumination system. The illumination optical system is configured to exist. Thereby, since the illumination area formed by the light from each light source can be stored in the effective area 30 without blocking the light from each light source, the light from each light source is efficiently synthesized by the synthesis surface 108. be able to.

<Third Embodiment>
FIG. 9 is a schematic view showing the arrangement of an exposure apparatus 90 in the third embodiment of the present invention. The exposure apparatus 90 is a lithography apparatus that employs the illumination optical system shown in the above-described embodiment and exposes a substrate.

  As an exposure method of the exposure apparatus, a projection method in which a mask (reticle) pattern is projected onto a substrate using a lens or a mirror, and a fine gap is provided between the mask and the substrate to transfer the mask pattern to the substrate. There is a proximity method. The projection method is generally more accurate than the proximity method in terms of pattern resolution performance and substrate magnification correction, and is suitable for manufacturing semiconductor devices. Therefore, in the present embodiment, a description will be given of a projection type exposure apparatus using a reflection type projection optical system for a glass substrate as the exposure apparatus 90.

  The exposure apparatus 90 transfers the pattern (for example, TFT circuit) formed on the mask M to the substrate P coated with a resist (photosensitive agent). The exposure apparatus 90 moves while holding an illumination optical system 99 that illuminates the mask M with light from a plurality of light sources 91, a mask stage 94 that holds and moves the mask M, a projection optical system 95, and a substrate P. A substrate stage 96 and a control unit 98. The illumination optical system 99 includes a first illumination system 92 that introduces light from a plurality of light sources 91 and a second illumination system 93 that guides light from the first illumination system 92 to the mask M.

  In the exposure apparatus 90, the illumination optical system 99, specifically, the first illumination system 92, employs the illumination optical system 100 or 200 shown in the above-described embodiment. The second illumination system 93 is an optical system that maintains the illuminated surface of the first illumination system 92 and the mask M (the surface thereof) in a substantially conjugate relationship. Accordingly, the first illumination system 92 uniformly illuminates the surface to be illuminated, so that the mask M is illuminated uniformly and in the same shape as the illumination shape by the first illumination system 92 via the second illumination system 93. be able to.

  The mask stage 94 is a stage device that can move in the XY directions while holding the mask M. The projection optical system 95 includes a reflection mirror 97 that changes the polarization characteristics of light, and forms an image of light from a pattern formed in the illuminated region of the mask M on the substrate P. The substrate stage 96 is a stage device that can move in the three-dimensional directions of XYZ while holding the substrate P. The control unit 98 includes a CPU, a memory, and the like, and controls the entire exposure apparatus 90 (operation).

  In the exposure, the light from the plurality of light sources 91 illuminates the mask M through the illumination optical system 99 (the first illumination system 92 and the second illumination system 93). The pattern of the mask M is projected onto the substrate P via the projection optical system 95. In the exposure apparatus 90 of the present embodiment, as described above, the illumination optical system 99 (illumination optical system 100 or 200) advantageous for efficiently illuminating the mask M using the light from the plurality of light sources 91 is used. Is adopted. Therefore, the exposure apparatus 90 can realize stable exposure performance and provide a high-quality device (semiconductor device, liquid crystal display device, flat panel display (FPD), etc.) with high throughput and high economic efficiency.

  In the exposure apparatus 90, the illuminance on the mask M changes according to the angle (attachment angle) of the Dove prism 106 included in the illumination optical system 100 or 200. For example, considering the case where the illumination optical system 100 is used, when the Dove prism 106 is rotated, the first illumination region 31, the second illumination region 32, and the third illumination region 33 shown in FIG. Rotate around 35 and 36. Therefore, depending on the angle of the Dove prism 106, the first illumination area 31, the second illumination area 32, and the third illumination area 33 may not fit in the effective area 30 (that is, a part thereof is located outside the effective area 30). Sometimes).

  Therefore, the exposure apparatus 90 includes a sensor SS that measures the illuminance on the substrate P (that is, the amount of light incident on the substrate P). For example, when the substrate P is illuminated in an arc shape, the sensor SS measures the illuminance at a plurality of points on the illumination area. In addition, the control unit 98 functions as an adjustment unit that adjusts the position of the illumination region with respect to the effective region 30 based on the illuminance measured by the sensor SS. Specifically, the angle of the Dove prism 106 included in the illumination optical system 100 or 200, the position of the deflection mirror 107, or the deflection angle is adjusted so that the illuminance measured by the sensor SS becomes the highest.

  Further, the Helmholtz Lagrangian amount can be defined as follows based on the characteristics of the illumination optical system and the projection optical system in the exposure apparatus. By obtaining the Helmholtz Lagrange amounts of the illumination optical system and the projection optical system, the illumination area of light from the light source and the effective area (capture area) can be compared.

  The Helmholtz Lagrange amount will be described with reference to FIGS. 11 and 12. FIG. 11 schematically shows the exposure apparatus, and shows an illumination optical system 1000 and a projection optical system 1005. In FIG. 11, 1001 denotes a light source unit, 1002 denotes a fly-eye lens, 1003 denotes a condenser lens, 1004 denotes a mask surface, and 1006 denotes a substrate surface. The mask pattern disposed on the mask surface 1004 is copied to a wafer or plate disposed on the substrate surface 1006 via the projection optical system 1005.

  FIG. 12A shows the magnitude of the intensity distribution or the incident angle of the light guided from the light source on the mask surface 1004. FIG. 12B shows the magnitude of the light intensity distribution or the incident angle when the light incident on the substrate surface 1006 is reverse-traced on the mask surface 1004.

FIG. 12A will be described. A rectangle is drawn (dotted line) so as to cover the distribution of light (solid line) guided from the light source unit 1001. The size of the rectangle is defined as _{X IL} and _{Y IL.} Further, the incident angle of light incident on the mask surface 1004 is defined as θ _IL .

Next, FIG. 12B will be described. Assume that the regions of light incident on the substrate surface 1006 are X _W and Y _W and the incident angle of the light incident on the substrate surface 1006 is θ _W. When the imaging magnification of the projection optical system 1005 is M, the light regions X _PO and Y _{PO on} the mask surface 1004 when back-traced from the substrate surface 1006 and the incident angle magnitude θ _PO are as follows: Can be expressed as
X _PO = X _W / M
Y _PO = Y _W / M
θ _PO = θ _W × M
The Helmholtz Lagrange amount (HX _IL , HY _IL ) of the illumination optical system 1000 and the Helmholtz Lagrange amount (HX _PO , HY _PO ) of the projection optical system 1005 can be defined as follows.
HX _IL = X _IL × θ _IL
HY _IL = Y _IL × θ _IL
HX _PO = X _PO × θ _PO
HY _PO = Y _PO × θ _PO
Here, by comparing the Helmholtz Lagrange amounts of the defined illumination optical system and projection optical system, it is possible to determine whether the light from the light source can be taken in efficiently. For example, when HX _IL > HX _PO , it is impossible to capture light emitted from the light source without loss. On the other hand, when HX _IL ≦ HX _PO , light emitted from the light source can be taken in without loss. Therefore, when the Helmholtz Lagrange amount of the illumination optical system is larger than the Helmholtz Lagrange amount of the projection optical system, the shape of the illumination region formed by the light from the light source is made non-circular and placed in the effective region as described above. Can be used effectively.

<Fourth Embodiment>
The device manufacturing method according to the present embodiment is suitable for manufacturing, for example, a semiconductor device, a liquid crystal display device, a flat panel display (FPD), and the like. The device manufacturing method includes a step of exposing a substrate (wafer, glass plate, etc.) coated with a resist (photosensitive agent) using the exposure apparatus 90, a step of developing the exposed substrate, and other well-known methods. And a process. The device manufacturing method of the present embodiment is advantageous in at least one of device performance, quality, productivity, and production cost as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

Claims (13)

An illumination optical system that illuminates an illuminated surface using light from a plurality of light sources,
A plurality of optical systems arranged corresponding to each of the plurality of light sources;
A synthesis system for guiding light from each of the plurality of optical systems to a conjugate plane optically conjugate with the illuminated surface;
An illumination system disposed between the conjugate surface and the surface to be illuminated;
For each of a plurality of illumination areas formed on the conjugate plane by light from each of the plurality of light sources via the plurality of optical systems and the synthesis system, the area has a non-circular shape, and The plurality of optical systems and the synthesis system are configured so as to fall within an effective area on the conjugate plane,
The illumination optical system according to claim 1, wherein the effective area is an area in which the illumination system can take in light for illumination of the illuminated surface in the conjugate plane area.   2. The illumination according to claim 1, wherein, for each of the plurality of illumination areas, the plurality of optical systems and the synthesis system are configured such that 95% or more of the areas are included in the effective area. Optical system. The plurality of light sources includes three or more light sources,
The plurality of optical systems includes three or more optical systems,
The three surfaces such that there are a plurality of surfaces orthogonal to the conjugate plane and including at least one principal ray of light from each of the three or more optical systems and the optical axis of the illumination system. The illumination optical system according to claim 1, wherein the optical system and the synthesis system are configured.   The illumination optical system according to claim 3, wherein chief rays of light from each of the three or more optical systems incident on the conjugate plane are parallel to each other. The effective area has a rectangular shape,
The plurality of light sources includes a first light source, a second light source, and a third light source,
The first illumination area, the second illumination area, and the third illumination area formed on the conjugate plane by the light from each of the first light source, the second light source, and the third light source are defined by strings and arcs. Have a shape
In the effective area,
A string of the second illumination area is parallel to one side of the effective area;
The second illumination area is disposed between a string of the first illumination area and a string of the third illumination area;
The plurality of optical systems and the synthesis system are configured so that the strings of the first illumination area or its extension line and the strings of the second illumination area or its extension line intersect the one side. The illumination optical system according to claim 1, wherein: The effective area has a rectangular shape,
The plurality of light sources include a first light source, a second light source, a third light source, and a fourth light source,
A first illumination area, a second illumination area, a third illumination area, and a fourth illumination formed on the conjugate plane by light from each of the first light source, the second light source, the third light source, and the fourth light source. The region has a shape defined by a chord and an arc,
In the effective area,
A string of the second illumination area is parallel to one side of the effective area;
A string of the third illumination region is parallel to a side opposite to the one side;
The second illumination region and the third illumination region are disposed between the strings of the first illumination region and the strings of the fourth illumination region;
The plurality of optical systems and the synthesis system are configured such that the strings of the first illumination area or its extension line and the strings of the fourth illumination area or its extension line intersect with the one side. The illumination optical system according to any one of claims 1 to 4. The effective area has a rectangular shape,
The plurality of light sources include a first light source, a second light source, a third light source, a fourth light source, a fifth light source, and a sixth light source,
A first illumination area formed on the conjugate plane by the light from each of the first light source, the second light source, the third light source, the fourth light source, the fifth light source, and the sixth light source; The region, the third illumination region, the fourth illumination region, the fifth illumination region, and the sixth illumination region have a shape defined by a string and an arc,
In the effective area,
The strings of the second illumination area and the strings of the fourth illumination area are parallel to one side of the effective area;
The strings of the third illumination area and the strings of the fifth illumination area are parallel to the side facing the one side;
The string of the first illumination region is parallel to the one side and the side orthogonal to the opposite side;
5. The optical system and the synthesis system are configured so that the strings of the sixth illumination region are parallel to a side facing the orthogonal side. 6. The illumination optical system according to claim 1. The synthesis system includes an optical member including a reflection surface that reflects light from the plurality of optical systems,
The illumination optical system according to claim 1, wherein the reflection surface is arranged so as to form the plurality of illumination regions on the conjugate surface. Each of the plurality of optical systems is
An elliptical mirror that reflects light from a corresponding light source among the plurality of light sources and collects it at a condensing point;
A spherical mirror that reflects light from the corresponding light source and condenses on the condensing point via the elliptical mirror;
The illumination optical system according to claim 1, wherein the illumination optical system includes: Each of the plurality of optical systems includes a prism on which light from a corresponding light source among the plurality of light sources enters,
The illumination optical system according to any one of claims 1 to 9, wherein an illumination region formed on the optically conjugate surface is rotated by rotating the prism. An exposure apparatus for transferring a mask pattern onto a substrate,
The illumination optical system according to any one of claims 1 to 10, wherein the mask is used as an illumination surface.
A projection optical system for projecting the pattern onto the substrate;
An exposure apparatus comprising: A sensor for measuring the amount of light incident on the substrate;
An adjustment unit that adjusts the positions of the plurality of illumination areas with respect to the effective area, based on the amount of light measured by the sensor;
The exposure apparatus according to claim 11, further comprising: Exposing the substrate using the exposure apparatus according to claim 11 or 12,
Developing the exposed substrate;
A device manufacturing method characterized by comprising:

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