Filter unit, illumination unit, exposure device, and exposure method

Abstract

This filter unit includes a plurality of filters disposed on the optical axis of an illumination optical system for illuminating a surface to be irradiated. The plurality of filters include a first filter having a first transmittance distribution and a second filter having a second transmittance distribution. The first transmittance distribution is formed, in the first direction of an orthogonal coordinate system in a plane orthogonal to the optical axis of the illumination optical system, according to a first function represented by an nth order expression (n is a natural number of 2 or more) in which coordinates in the first direction are variables, and the relative positions of the first filter and the second filter can be changed at least in the first direction.

Description

Filter unit, illumination unit, exposure apparatus, and exposure method

[0001] The present invention relates to a filter unit, an illumination unit, an exposure apparatus, and an exposure method.

[0002] In recent years, liquid crystal display panels have come into widespread use as display elements for personal computers, televisions, and the like. Liquid crystal display panels are manufactured by forming a circuit pattern of thin-film transistors on a plate (glass substrate) using a photolithography technique. An exposure apparatus is used for this photolithography process, which projects and exposes an original pattern formed on a mask onto a photoresist layer on the plate via a projection optical system (see, for example, Patent Document 1).

[0003] It is desirable to improve the illuminance uniformity of the exposure light.

[0004] Japanese Patent Application Laid-Open No. 2000-21712

[0005] According to a first aspect of the disclosure, the filter unit includes a plurality of filters arranged on the optical axis of an illumination optical system that illuminates an illuminated surface, the plurality of filters including a first filter having a first transmittance distribution and a second filter having a second transmittance distribution, the first transmittance distribution being formed in a first direction of a Cartesian coordinate system in a plane orthogonal to the optical axis of the illumination optical system according to a first function expressed as an n-th degree equation (n is a natural number greater than or equal to 2) with coordinates in the first direction as variables, and the relative positions of the first filter and the second filter being changeable at least in the first direction.

[0006] According to a second aspect of the disclosure, the lighting unit comprises an optical integrator into which light emitted from a light source is incident, and the above-mentioned filter unit, and the light emitted from the optical integrator is incident on the filter unit.

[0007] According to a third aspect of the disclosure, the exposure apparatus comprises a plurality of the above-mentioned illumination units, and a plurality of projection optical units corresponding to the plurality of illumination units and projecting pattern images of a mask illuminated by the plurality of illumination units onto a photosensitive substrate, the plurality of projection optical units including a first projection optical unit and a second projection optical unit, and the exposure area of ​​the first projection optical unit and the exposure area of ​​the second projection optical unit partially overlap.

[0008] According to a fourth aspect of the disclosure, an exposure method is an exposure method using the above-mentioned exposure apparatus, and includes illuminating the mask using the illumination unit and projecting the pattern image of the mask onto the photosensitive substrate using the projection optical unit.

[0009] According to a fifth aspect of the disclosure, a filter unit includes a plurality of filters arranged on an optical axis of an optical system, the plurality of filters including a first filter having a first transmittance distribution and a second filter having a second transmittance distribution, wherein the first transmittance distribution is non-uniform in a first direction of a Cartesian coordinate system in a plane perpendicular to the optical axis of the optical system, the second transmittance distribution is non-uniform in the first direction, and a relative position of the first filter and the second filter is changeable in at least the first direction.

[0010] According to a sixth aspect of the disclosure, the lighting unit includes an optical integrator onto which light emitted from a light source is incident, and the filter unit onto which the light emitted from the optical integrator is incident.

[0011] According to a seventh aspect of the disclosure, the exposure apparatus includes a plurality of the above-mentioned illumination units and a plurality of projection optical units corresponding to the plurality of illumination units, the plurality of projection optical units including a first projection optical unit and a second projection optical unit, and the exposure area of ​​the first projection optical unit and the exposure area of ​​the second projection optical unit partially overlap.

[0012] According to an eighth aspect of the disclosure, an exposure method is an exposure method using the above-mentioned exposure apparatus, and includes illuminating the mask using the plurality of illumination units, and projecting the pattern image of the mask onto the photosensitive substrate using the plurality of projection optical units.

[0013] According to a ninth aspect of the disclosure, a filter unit includes a plurality of filters arranged on an optical axis of an optical system, the plurality of filters including a first filter, a second filter, and a third filter, the first filter having a first transmittance distribution in a region where illumination light is incident, the first filter having a first transmittance distribution that is non-uniform in a first direction intersecting the optical axis, the second filter having a second transmittance distribution in a region where the illumination light is incident and that is non-uniform in the first direction and different from the first transmittance distribution, the third filter having a third transmittance distribution in a region where the illumination light is incident and that is non-uniform in the first direction and different from the first transmittance distribution and the second transmittance distribution, the filter unit having a first composite transmittance distribution when the first filter, the second filter, and the third filter are each at a reference position in the first direction, and a second composite transmittance distribution when the first filter is at a position other than the reference position in the first direction and the second filter and the third filter are each at the reference position in the first direction, When the second filter and the third filter are each at the reference position in the first direction and the second filter is at a position other than the reference position in the first direction, the second filter has a third composite transmittance distribution, the first composite transmittance distribution has a transmittance within a predetermined range, and the second composite transmittance distribution monotonically increases from one side to the other side in the first direction so that the transmittance is smaller than the lower limit of the predetermined range on one side in the first direction and larger than the upper limit of the predetermined range on the other side in the first direction, or monotonically decreases from one side to the other side in the first direction so that the transmittance is larger than the upper limit of the predetermined range on the one side in the first direction and smaller than the lower limit of the predetermined range on the other side in the first direction, and the third composite transmittance distribution is convex toward a higher transmittance so that the transmittance is smaller than the lower limit of the predetermined range on both the one side and the other side in the first direction, or is convex toward a lower transmittance so that the transmittance is larger than the upper limit of the predetermined range on both the one side and the other side in the first direction.

[0014] According to a tenth aspect of the disclosure, an illumination unit includes a fly-eye lens arranged on an optical axis, and the filter unit onto which the illumination light is incident via the fly-eye lens.

[0015] According to an eleventh aspect of the disclosure, an exposure apparatus includes a first illumination optical system, which is the illumination optical system that illuminates a mask; a first projection optical system that irradiates a substrate with light from the first illumination optical system via the mask; a second illumination optical system different from the first illumination optical system that illuminates the mask; and a second projection optical system different from the first projection optical system that irradiates the substrate with light from the second illumination optical system via the mask, and performs continuous exposure using the first projection optical system and the second projection optical system while moving the substrate in a scanning direction corresponding to the second direction.

[0016] According to a twelfth aspect of the disclosure, an exposure apparatus includes the above-mentioned illumination optical system that illuminates a mask, and a projection optical system that irradiates a substrate with light from the illumination optical system via the mask, and scans and exposes a first region of the substrate using the projection optical system while moving the substrate in a scanning direction corresponding to the second direction, and then scans and exposes a second region of the substrate that overlaps with a portion of the first region and is different from the first region using the projection optical system while moving the substrate in a direction parallel to the scanning direction.

[0017] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiments.

[0018] FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus according to an embodiment. FIG. 2 is a perspective view showing the arrangement of multiple projection optical units. FIG. 3A is a diagram showing the exposure fields of multiple projection optical units on a substrate, and FIG. 3B is a diagram showing an exposure area formed on the substrate when the substrate is scanned in the X direction by a substrate stage and exposed using the exposure field shown in FIG. 3A. FIG. 4 is a schematic diagram showing the configuration of an illumination unit according to an embodiment. FIG. 5A is a schematic diagram showing the configuration of a filter unit, and FIG. 5B is a schematic plan view of a first movable filter, a second movable filter, and a fixed filter. FIG. 6A is a diagram showing a composite transmittance distribution obtained when the first movable filter, the second movable filter, and the fixed filter are each at a reference position. FIG. 6B is a diagram showing a composite transmittance distribution obtained when the position of the first movable filter is shifted from the reference position in the Y-axis direction. FIG. 6C is a diagram showing a composite transmittance distribution obtained when the position of the second movable filter is shifted from the reference position in the Y-axis direction. Fig. 7(A) is a diagram showing a composite transmittance distribution obtained when a fourth filter having a fourth transmittance distribution formed according to a quadratic equation in the Y-axis direction and a fifth filter having a fifth transmittance distribution complementary to the fourth transmittance distribution are at a reference position, Fig. 7(B) is a diagram showing a composite transmittance distribution obtained when the fifth filter is moved by Δy (<0) in the Y-axis direction, Fig. 8(A) is a diagram showing an example of a fourth transmittance distribution expressed by a function having only fourth-order terms and a fourth transmittance distribution expressed by a function having only fifth-order terms, and Fig. 8(B) is a diagram showing an example of a fourth transmittance distribution expressed by a function combining a function having only fifth-order terms, a function having only third-order terms, and a function having only first-order terms.

[0019] An exposure apparatus 10 according to one embodiment will be described with reference to FIGS. 1 to 8B.

[0020] (Configuration of Exposure Apparatus) FIG. 1 is a diagram that shows schematically the configuration of an exposure apparatus 10 according to an embodiment.

[0021] The exposure apparatus 10 is a scanning stepper (scanner) that drives a mask MSK and a glass substrate (hereinafter referred to as "substrate") P in the same direction and at the same speed relative to a projection optical system PL, thereby transferring a pattern formed on the mask MSK onto the substrate P. The substrate P is a rectangular glass substrate used in, for example, a liquid crystal display device (flat panel display), with at least one side or diagonal length of 500 mm or more.

[0022] In the following, the direction in which the mask MSK and substrate P are driven during scanning exposure (scanning direction) is referred to as the X-axis direction, the direction in the horizontal plane perpendicular to this is referred to as the Y-axis direction, the direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are referred to as the θx, θy, and θz directions, respectively.

[0023] The exposure apparatus 10 includes an illumination system IOP, a mask stage MST that holds a mask MSK, a projection optical system PL, a body 70 that supports these, a substrate stage PST that holds a substrate P, and a control system for these. The control system provides overall control of each component of the exposure apparatus 10.

[0024] The body 70 includes a base (vibration isolation table) 71, columns 72A and 72B, an optical surface plate 73, a support 74, and a slide guide 75. The base (vibration isolation table) 71 is placed on a floor F and supports the columns 72A, 72B, etc., while isolating vibrations from the floor F. The columns 72A and 72B each have a frame shape, with the column 72A being placed inside the column 72B. The optical surface plate 73 has a flat plate shape and is fixed to the ceiling of the column 72A. The support 74 is supported by the ceiling of the column 72B via a slide guide 75. The slide guide 75 includes an air ball lifter and a positioning mechanism, and positions the support 74 (i.e., the mask stage MST, described later) at an appropriate position in the X-axis direction relative to the optical surface plate 73.

[0025] The illumination system IOP is disposed above the body 70. The illumination system IOP irradiates the mask MSK with illumination light IL. The detailed configuration of the illumination system IOP will be described later.

[0026] The mask stage MST is supported by a support 74. A mask MSK having a pattern surface (the lower surface in FIG. 1 ) on which a circuit pattern is formed is fixed to the mask stage MST by, for example, vacuum suction (or electrostatic suction). The mask stage MST is driven by a drive system including, for example, a linear motor at a predetermined stroke in the scanning direction (X-axis direction), and is also driven slightly in the non-scanning directions (Y-axis direction and θz direction).

[0027] Position information of the mask stage MST in the XY plane (including rotation information in the θz direction) is measured by an interferometer system. The interferometer system measures the position of the mask stage MST by irradiating a measurement beam onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the mask stage MST and receiving the light reflected from the movable mirror. The measurement results are supplied to a control device (not shown), which drives the mask stage MST via a drive system in accordance with the measurement results of the interferometer system.

[0028] The projection optical system PL is supported by an optical surface plate 73 below (on the -Z side of) the mask stage MST. The projection optical system PL is configured in a similar manner to the projection optical system disclosed in, for example, U.S. Patent No. 5,729,331, and includes multiple (e.g., seven) projection optical units 100a-100g (multi-lens projection optical units) in which the projection areas of the pattern image of the mask MSK are arranged in a staggered pattern. Note that, of the seven projection optical units 100a-100g, only four projection optical units 100a, 100c, 100e, and 100g are shown in FIG. 1.

[0029] 2 is a perspective view showing a schematic arrangement of the multiple projection optical units 100a to 100g. Here, four projection optical units 100a, 100c, 100e, and 100g are arranged at predetermined intervals in the Y-axis direction, and the remaining three projection optical units 100b, 100d, and 100f are arranged at predetermined intervals in the Y-axis direction, spaced apart from the four projection optical units 100a, 100c, 100e, and 100g on the +X side. Each of the multiple projection optical units 100a to 100g is, for example, a double-telecentric, 1:1 system that forms an erect, normal image.

[0030] 3A is a diagram showing the exposure fields PIa to PIe of the seven projection optical units 100a to 100g on the substrate P. The exposure fields PIa, PIc, PIe, and PIg of the projection optical units 100a, 100c, 100e, and 100g, which are arranged in order in the +Y direction, are trapezoids with the shorter side of the two sides parallel to the Y direction on the +X side and the longer side on the -X side. On the other hand, the exposure fields PIb, PId, and PIf of the projection optical units 100b, 100d, and 100f, which are arranged in order in the +Y direction, are trapezoids with the shorter side of the two sides parallel to the Y direction on the -X side and the longer side on the +X side.

[0031] The exposure field PIa, which is located at the end in the -Y direction, has its illumination light blocked by a field stop (not shown) so that its -Y end is parallel to the X direction. Also, the exposure field PIg, which is located at the end in the +Y direction, has its illumination light blocked by a field stop so that its +Y end is parallel to the X direction.

[0032] Figure 3(B) is a diagram showing exposure areas formed on substrate P when substrate P is scanned in the X direction by substrate stage PST and exposed by exposure fields PIa to PIg shown in Figure 3(A). Exposure areas (scanning exposure fields) SIa to SIg exposed by each exposure field PIa to PIg by scanning exposure are formed on substrate P. In Figure 3(B), exposure fields SIa, SIc, SIe, and SIg formed by projection optical units 100a, 100c, 100e, and 100g are indicated by dashed dotted lines, and exposure fields SIb, SId, and SIf formed by projection optical units 100b, 100d, and 100f are indicated by dashed two-dotted lines.

[0033] These exposure areas SIa to SIg are formed by extending the exposure fields PIa to PIg in the X direction through scanning exposure in the X direction. The ends of each exposure area SIa to SIg in the Y direction (non-scanning direction) overlap with the ends of the adjacent exposure areas SIa to SIg in the non-scanning direction.

[0034] When the illumination area on the mask MSK is illuminated by illumination light IL from the illumination system IOP, the illumination light IL that has passed through the mask MSK forms a projected image (partial erect image) of the circuit pattern of the mask MSK within that illumination area, via the projection optical system PL, in an irradiation area (exposure area (conjugate to the illumination area)) on the substrate P, which is arranged on the image plane side of the projection optical system PL. Here, a resist (sensitizer) is applied to the surface of the substrate P. By synchronously driving the mask stage MST and the substrate stage PST, i.e., by driving the mask MSK in the scanning direction (X-axis direction) relative to the illumination area (illumination light IL) and driving the substrate P in the same scanning direction relative to the exposure area (illumination light IL), the substrate P is exposed and the pattern of the mask MSK is transferred onto the substrate P.

[0035] The substrate stage PST is disposed on a base (vibration isolation table) 71 below (on the -Z side of) the projection optical system PL. The substrate P is held on the substrate stage PST via a substrate holder (not shown).

[0036] Position information of the substrate stage PST in the XY plane (including rotation information (yawing amount (rotation amount θz in the θz direction), pitching amount (rotation amount θx in the θx direction), and rolling amount (rotation amount θy in the θy direction))) is measured by an interferometer system. The interferometer system measures the position of the substrate stage PST by irradiating a measurement beam from the optical surface plate 73 onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the substrate stage PST, and receiving the reflected light from the movable mirror. The measurement results are supplied to a control device (not shown), and the control device drives the substrate stage PST in accordance with the measurement results of the interferometer system.

[0037] In exposure apparatus 10, alignment measurement (for example, EGA, etc.) is performed prior to exposure, and the results are used to expose substrate P in the following procedure. First, in accordance with instructions from the control device, mask stage MST and substrate stage PST are synchronously driven in the X-axis direction. This performs scanning exposure on the first shot area on substrate P. When scanning exposure on the first shot area is completed, the control device moves (steps) substrate stage PST to a position corresponding to the second shot area. Then, scanning exposure is performed on the second shot area. Similarly, the control device repeats stepping between shot areas on substrate P and scanning exposure on the shot areas to transfer the pattern of mask MSK to all shot areas on substrate P.

[0038] (Configuration of illumination system IOP) Next, the configuration of illumination system IOP in this embodiment will be described. FIG. 4 is a diagram schematically showing the configuration of illumination system IOP. As shown in FIG. 4, illumination system IOP includes a light source section 20 and a plurality of illumination optical systems (illumination units) 80a to 80g (see FIG. 2) corresponding to the plurality of projection optical units 100a to 100g included in projection optical system PL, respectively. Note that FIG. 4 illustrates illumination optical system 80a and illumination optical system 80b, of the plurality of illumination optical systems 80a to 80g, which are arranged spaced apart in the X direction. Note that in the following description, unless a particular distinction is required, illumination optical systems 80a to 80g may be referred to as illumination optical system 80.

[0039] The light source unit 20 includes a light source 21 such as a mercury lamp, an elliptical mirror 22, a bending mirror 23, a relay lens 24, a bending mirror 25, a relay lens 26, and an optical fiber 27. Illumination light supplied from the light source 21 is supplied to illumination optical systems 80a to 80g via a light guide optical system including the elliptical mirror 22, the bending mirror 23, the relay lens 24, the bending mirror 25, the relay lens 26, and the optical fiber 27. The optical fiber 27 splits the illumination light incident on a single incident side 271 approximately evenly and outputs the split light to seven exit sides 272a to 272g (only two are shown in FIG. 4). Note that a laser light source, a UV (Ultra Violet)-LED (Light Emitting Diode) light source, or the like may also be used as the light source 21.

[0040] Since the illumination optical systems 80a to 80g have the same configuration, only the illumination optical system 80a will be described. The illumination optical system 80a includes an input lens 83, a fly-eye lens FEL, a condenser lens 84, and a filter unit 85. Note that an optical integrator other than a fly-eye lens (such as a rod integrator) may also be used.

[0041] The illumination light emitted from the exit side 272a of the optical fiber 27 enters the input lens 83 provided in the illumination optical system 80a.

[0042] The fly's eye lens FEL is formed, for example, by arranging a large number of lens elements, each having positive refractive power, densely and vertically so that their optical axes are parallel to the reference optical axis AXa. Each lens element constituting the fly's eye lens FEL has a rectangular cross section similar to the shape of the illumination field to be formed on the mask MSK (and thus the shape of the exposure area to be formed on the substrate P). In the following description, unless there is a particular need to distinguish between them, the reference optical axis AXa and the reference optical axis AXb of the illumination optical system 80b may be referred to as the optical axis AX.

[0043] Therefore, the light beam incident on the fly-eye lens FEL is wavefront-split by the multiple lens elements, and one light source image is formed on or near the rear focal plane (exit surface) of each lens element. That is, a substantial surface light source, i.e., a secondary light source, consisting of multiple light source images is formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL. The light beam from the secondary light source formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL is subjected to the focusing action of the condenser lens 84, and then illuminates the filter unit 85 in a superimposed manner.

[0044] In exposure apparatuses, it is desirable to improve the illuminance uniformity of the illumination light IL (exposure light) that illuminates the mask MSK. Furthermore, after scanning exposure of the first shot area on the substrate P is completed, the substrate stage PST is moved (stepped) to a position corresponding to the second shot area (the first and second shot areas are aligned in the non-scanning direction), and scanning exposure of the second shot area is then performed so that it overlaps with a portion of the first shot area (in the case of image compositing). By driving the light-shielding plate so that it overlaps with the opening of a trapezoidal field stop included in the projection optical unit that exposes the overlapping portion of the first and second shot areas (the seam in the image compositing), the size of the exposure field (trapezoidal) of the projection optical unit that exposes the seam in the image compositing can be changed, thereby making it possible to vary the position of the seam in the image compositing. In this case, it is preferable to suppress nonuniformity in the illuminance distribution in the X-axis direction (scanning direction). It is preferable to position the field stop approximately conjugate with the mask MSK and the substrate P.

[0045] Therefore, the exposure apparatus 10 according to the present embodiment is provided with a filter unit 85 that has the function of making the illuminance distribution of the illumination light IL that illuminates the mask MSK uniform. The illumination light IL, whose illuminance distribution has been made uniform by the filter unit 85, illuminates the mask MSK.

[0046] Next, a description will be given of the configuration of the filter unit 85. FIG.

[0047] The filter unit 85 includes a first movable filter 85a (first filter), a second movable filter 85b (third filter), and a fixed filter 85c (second filter) arranged along the optical axis AX (corresponding to the Z-axis direction).

[0048] The first movable filter 85 a, the second movable filter 85 b, and the fixed filter 85 c each have the form of a plane-parallel plate made of an optical material such as quartz or an i-line glass, and have a substantially constant thickness. A dense pattern of light-shielding dots made of chromium, chromium oxide, or the like is formed on the optical surface of each of the first movable filter 85 a, the second movable filter 85 b, and the fixed filter 85 c.

[0049] Each of the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c has a transmittance distribution that differs depending on the position of incidence of light (more specifically, the position in the X-axis direction and the Y-axis direction).

[0050] 5B is a schematic plan view of the first movable filter 85 a, the second movable filter 85 b, and the fixed filter 85 c. The first movable filter 85 a, the second movable filter 85 b, and the fixed filter 85 c each have, for example, a circular outer shape centered on the optical axis AX.

[0051] In this embodiment, the first movable filter 85a is configured to be movable along the X-axis and Y-axis directions while maintaining a position such that its incident surface is perpendicular to the optical axis AX. The second movable filter 85b is configured to be movable along the Y-axis direction while maintaining a position such that its incident surface is perpendicular to the optical axis AX. Note that the second movable filter 85b may also be configured to be movable in the X-axis direction.

[0052] As a result, in this embodiment, the relative position between the first movable filter 85a and the fixed filter 85c can be changed in the X-axis direction and the Y-axis direction. Also, the relative position between the second movable filter 85b and the fixed filter 85c can be changed in the Y-axis direction. Note that the position where the center of each of the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c coincides with the optical axis AX is referred to as the reference position.

[0053] Next, the transmittance distributions of the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c will be described.

[0054] As shown in FIG. 5B, when an XY coordinate system (orthogonal coordinate system) is defined with the center of the circular first movable filter 85a (coincident with the optical axis AX) as the origin, the first movable filter 85a has a first transmittance distribution T １ (x, y).

[0055] More specifically, the first transmittance distribution T １(x, y) is a function Ty expressed by an n-th degree equation (n is a natural number of 2 or more) with the y coordinate as a variable in the Y-axis direction. １ (y).

[0056] In addition, the first transmittance distribution T １ (x, y) is a function Tx expressed by a k-th degree equation (k is a natural number of 2 or more) with the x coordinate as a variable in the X-axis direction. １ (x).

[0057] The second movable filter 85b has a second transmittance distribution T ２ (x, y). More specifically, the second transmittance distribution T ２ (x, y) is a function Ty expressed by an m-th degree equation (m is a natural number of 2 or more) with the y coordinate as a variable in the Y-axis direction. ２ (y).

[0058] In this embodiment, the second transmittance distribution T ２ (x, y) has the same transmittance (for example, 100%) in the X-axis direction. That is, the second transmittance distribution T ２ (x, y) is the function Tx ２ It is formed according to (x)=const (const is a constant).

[0059] The fixed filter 85c has a first transmittance distribution T １ (x, y) and the second transmittance distribution T ２ (x, y) and a third transmittance distribution T ３ (x, y), where the first transmittance distribution T １ (x, y) and the second transmittance distribution T ２ (x, y) is complementary to the first transmittance distribution T １ (x, y) and the third transmittance distribution T ３ The product of (x, y) is substantially constant (almost flat), and the second transmittance distribution T ２ (x, y) and the third transmittance distribution T ３ This means that the product of (x, y) is approximately constant (almost flat).

[0060] Third transmittance distribution T ３(x, y) is the function Ty １ (y) and function Ty ２ (y) and the complementary function Ty ３ (y), where the function Ty １ (y) and function Ty ２ (y) is complementary to the function Ty １ (y) and function Ty ３ (y) is approximately constant (almost flat), and the function Ty ２ (y) and function Ty ３ (y) is approximately constant. ３ (x, y) is the function Tx １ The function Tx complementary to (x) ３ (x), where the function Tx １ The function Tx is complementary to (x). １ (x) and function Ty ３ This means that the product with (y) is approximately constant.

[0061] In the following description, the function Ty １ (y) is the first transmittance distribution Ty in the Y-axis direction １ (y) and the function Ty ２ (y) is the second transmittance distribution Ty in the Y-axis direction ２ (y) and the function Tx １ (x) is the first transmittance distribution Tx in the X-axis direction １ (x). Also, the function Ty ３ (y) is the third transmittance distribution Ty in the Y-axis direction ３ It may be written as (y).

[0062] The light incident on the filter unit 85 passes through the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c in this order. At this time, the illuminance distribution of the light incident on the filter unit 85 is a first transmittance distribution T １ (x, y), second transmittance distribution T ２ (x, y), and the third transmittance distribution T ３ (x, y) ｃｍｂIn the following description, the composite transmittance distribution in the Y-axis direction is referred to as T ｃｍｂ It is represented by (y).

[0063] Here, the composite transmittance distribution will be described. For ease of explanation and understanding, correction of the illuminance distribution in the Y-axis direction will be described below, but the same applies to correction of the illuminance distribution in the X-axis direction.

[0064] Fig. 6(A) is a diagram showing a composite transmittance distribution in the Y-axis direction obtained when the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c are each in a reference position, Fig. 6(B) is a diagram showing a composite transmittance distribution obtained when the position of the first movable filter 85a is shifted from the reference position in the Y-axis direction, and Fig. 6(C) is a diagram showing a composite transmittance distribution obtained when the position of the second movable filter 85b is shifted from the reference position in the Y-axis direction. Note that in Figs. 6(A) to 6(C), the function Ty １ (y) is Ty １ (y) = αy ２ +β (α and β are arbitrary coefficients), and is a function Ty ２ (y) is Ty ２ (y) = γy ３ +ωy+λ (γ, ω, λ are arbitrary coefficients).

[0065] As shown in FIG. 6A, the third transmittance distribution Ty ３ (y) is the first transmittance distribution Ty in the Y-axis direction １ (y) and the second transmittance distribution Ty in the Y-axis direction ２ (y), the composite transmittance distribution Ty in the Y-axis direction obtained when the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c are each in the reference position is ｃｍｂ (y) is approximately constant (almost flat) in the Y-axis direction.

[0066] As shown in FIG. 6B, when the position of the first movable filter 85a is shifted from the reference position in the Y-axis direction, the resulting composite transmittance distribution Tyｃｍｂ (y) is the first transmittance distribution Ty １ Therefore, when the illuminance distribution is inclined in the Y-axis direction, the first transmittance distribution in the Y-axis direction is expressed as Ty １ (y) = αy ２ By using the first movable filter 85a represented by +β, it is possible to correct the illuminance distribution tilted in the Y-axis direction. This is called tilt correction.

[0067] Furthermore, as shown in FIG. 6C, when the position of the second movable filter 85b is shifted from the reference position in the Y-axis direction, the resulting composite transmittance distribution Ty ｃｍｂ (y) is the second transmittance distribution Ty in the Y-axis direction ２ Therefore, when the illuminance distribution is curved in the Y-axis direction, the second transmittance distribution in the Y-axis direction is expressed as Ty ２ (y) = γy ３ +ωy+λ, the illuminance distribution curved in the Y-axis direction can be corrected. This is called curvature correction.

[0068] Here, when the position of the first movable filter 85a is shifted from the reference position in the Y-axis direction and when the position of the second movable filter 85b is shifted from the reference position, the composite transmittance distribution Ty ｃｍｂ (y) is the first transmittance distribution Ty in the Y-axis direction １ (y) and second transmittance distribution Ty in the Y-axis direction ２ The principle behind the degree being one order lower than the degree of (y) will be explained.

[0069] FIG. 7A shows a fourth transmittance distribution Ty formed in accordance with a quadratic equation in the Y-axis direction. ４ a fourth filter having a fourth transmittance distribution Ty ４ and a fifth transmittance distribution Ty ５ 7(A) and 7(B) are diagrams showing the composite transmittance distribution obtained when the fifth filter having the same is at the reference position, and FIG. 7(B) is a diagram showing the composite transmittance distribution obtained when the fifth filter is moved by Δy (<0) in the Y-axis direction.

[0070] Fourth transmittance distribution Ty ４ and the fifth transmittance distribution Ty ５ are complementary to each other, so This can be expressed as:

[0071] In this case, when the fourth filter and the fifth filter are in the reference position, the composite transmittance distribution is and f(y) ２ <<T ａｖｅ ２ Therefore, As a result, the combined transmittance distribution becomes substantially constant (almost flat) as shown in FIG.

[0072] On the other hand, when the fifth filter is shifted by Δy, the fourth transmittance distribution Ty ４ and the fifth transmittance distribution Ty ５ and respectively, This can be expressed as:

[0073] In this case, the composite transmittance distribution of the fourth transmittance distribution and the fifth transmittance distribution is expressed as follows: It can be seen that the transmittance distribution is expressed by an equation that is one order smaller than the fourth transmittance distribution.

[0074] From the above, when the fourth transmittance distribution is formed according to a function expressed by a jth-order equation (j is a natural number of second or higher order), by combining the fourth filter with a fifth filter having a fifth transmittance distribution complementary to the fourth transmittance distribution, a composite transmittance distribution expressed by a j-1th-order equation can be obtained.

[0075] That is, when the target composite transmittance distribution is expressed by a j-1th degree equation, the fourth transmittance distribution of the fourth filter can be expressed by a jth degree equation. However, the larger j (the higher the degree of the function representing the fourth transmittance distribution), the larger the transmittance range (the difference between the minimum transmittance and the maximum transmittance). Therefore, it is preferable that the fourth transmittance distribution in the Y-axis direction has terms of the j-1th degree or lower. This point will be explained below.

[0076] FIG. 8A shows a function f1(y)=ay that has only fourth-order terms. ４(a is an arbitrary coefficient) and a function f2(y)=by ５ 8A is a diagram illustrating a fourth transmittance distribution expressed by the function f2(y)=by (b is an arbitrary coefficient). ５ The transmittance width W2 of the fourth transmittance distribution expressed by the function f1(y)=ay ４ The transmittance width W1 of the fourth transmittance distribution expressed by the function (4) is larger than the transmittance width W1 of the fourth transmittance distribution expressed by the function (4). Thus, the transmittance width increases as the order of the function expressing the fourth transmittance distribution increases. If the transmittance width increases, the transmittance decreases too much when the fourth filter is shifted from the reference position, resulting in a decrease in the illuminance of the illumination light.

[0077] The inventors have found that in the fourth transmittance distribution expressed by a function of degree j, the transmittance width can be reduced by including terms of degree j-1 or less. ５ (b is an arbitrary coefficient) and the function f3(y) = c ３ (c is an arbitrary coefficient) and function f4(y) = py (p is an arbitrary coefficient) and function f5(y) = f2(y) + f3(y) + f4(y) = by ５ +cy ３ 10 is a diagram showing a fourth transmittance distribution formed in accordance with +py.

[0078] 8B, it can be seen that the transmittance width W3 of the fourth transmittance distribution formed according to the function f5(y) is smaller than the transmittance width W2 of the fourth transmittance distribution formed according to the function f2(y). In this way, the transmittance width can be reduced by including terms of the j-th degree or lower in the function expressed by the jth degree equation that represents the transmittance distribution.

[0079] Therefore, in this embodiment, the second transmittance distribution Ty ２ (y) is a cubic equation (γy) containing a first-order term (ωy). ３ +ωy+λ) By configuring in this way, it is possible to narrow the transmittance range and suppress a decrease in transmittance.

[0080] The illuminance in the illumination area formed by a plurality of illumination units was measured and the illuminance uniformity was investigated when a conventional filter unit was used and when the filter unit 85 according to this embodiment was used.

[0081] In a conventional filter unit, a plurality of filters each having a dense pattern of light-shielding dots are prepared, and each filter has a transmittance distribution that varies depending on the position of incidence of light (more specifically, the position in the X-axis direction and the Y-axis direction), and a predetermined transmittance distribution corresponding to tilt correction and curvature correction is formed. In this filter unit, a filter corresponding to the illuminance distribution to be corrected is selected, and the filter is rotated to correct the non-uniformity (illuminance unevenness) of the illuminance distribution in the Y-axis direction, which is calculated by averaging the integrated scanning illuminance in the X-axis direction (referred to as the scan average).

[0082] Using the illuminance distribution of the entire illumination area combining multiple illumination optical systems, the illuminance distribution in the Y-axis direction after scan averaging, and the illuminance change rate of that Y-axis illuminance distribution as indicators, we investigated the extent to which illuminance unevenness could be corrected when using conventional methods and the method according to this embodiment for multiple illuminance unevenness data that reflect the manufacturing accuracy of the exposure device.

[0083] In the conventional method, the evaluation was carried out under the condition that a filter unit for performing tilt correction and curvature correction was installed, and the rotation angle was calculated for the uneven illuminance of each data, correction was performed, and the above index value was calculated.

[0084] In this embodiment, the evaluation was performed under the condition that the movable filter was equipped with tilt correction in the X-axis direction and Y-axis direction and curvature correction in the Y-axis direction, and the amount of movement in the X-axis direction and Y-axis direction was calculated for the illuminance unevenness of each data, correction was performed, and the above index value was calculated.

[0085] When comparing the average values ​​of the survey data, it was calculated that the method according to this embodiment can reduce illuminance unevenness to approximately 50% or less compared to the conventional method in all of the above indexes.

[0086] In particular, the conventional method is designed to correct illuminance unevenness after averaging the scan, and there are limitations to correcting illuminance unevenness across the entire illumination area, but the method according to this embodiment ensures the degree of freedom to correct illuminance unevenness across the entire illumination area by appropriately calculating the amount of movement of the movable filter, and is able to reduce illuminance unevenness to about one-third or less on average compared to the conventional method. Thus, it has been shown that the filter unit 85 according to this embodiment exhibits a significant improvement in illuminance unevenness compared to conventional filter units.

[0087] As described above, it was confirmed that the use of the filter unit 85 according to this embodiment improved the illuminance uniformity.

[0088] As described above in detail, according to this embodiment, the filter unit 85 includes a plurality of filters arranged on the optical axis AX of the illumination optical system 80 that illuminates the mask MSK. １ a first movable filter 85a having a transmittance distribution T ３ and a fixed filter 85c having a first transmittance distribution T １ (x, y) is a function Ty expressed by an n-th degree equation (n is a natural number of 2 or more) in which the coordinate in the Y-axis direction of the XY coordinate system in a plane perpendicular to the optical axis AX of the illumination optical system 80 is a variable. １ (y), and a third transmittance distribution T ３ (x, y) is the first transmittance distribution Ty １ (y), and the relative positions of the first movable filter 85a and the fixed filter 85c are changeable at least in the Y-axis direction.

[0089] As a result, as explained using Figures 7(A) and 7(B), by moving the first movable filter 85a from the reference position, a composite transmittance distribution expressed by an n-1th order equation can be generated, and the illuminance distribution of the illumination light IL can be corrected by the composite transmittance distribution expressed by an n-1th order equation.

[0090] In this embodiment, the plurality of filters have a second transmittance distribution T ２The second transmittance distribution is a function Ty expressed by an m-th degree equation (m is a natural number of 2 or more) in which the coordinate in the Y-axis direction is a variable. ２ (y), and the third transmittance distribution T ３ (x, y) is the first transmittance distribution Ty in the Y-axis direction １ (y) and the second transmittance distribution Ty ２ (y), and the relative position between the fixed filter 85c and the second movable filter 85b is changeable in the Y-axis direction.

[0091] As a result, by moving the second movable filter 85b by Δy in the Y-axis direction, a composite transmittance distribution expressed by an m-1-th order equation can be generated, and the illuminance distribution of the illumination light IL can be corrected by the composite transmittance distribution expressed by an m-1-th order equation.

[0092] In this embodiment, the function Ty ２ (y) has terms of order m-1 or lower. As a result, as described with reference to FIGS. 8A and 8B, the transmittance range, which is the difference between the maximum transmittance and the minimum transmittance of the second movable filter 85b, can be reduced. This makes it possible to suppress a decrease in the illuminance of the illumination light IL caused by the filter unit 85.

[0093] In this embodiment, the function Ty ２ The order (third order) of (y) is a function Ty １ This is larger than the order (second order) of (y). This makes it possible to assign different correction functions (tilt correction, curvature correction) to the first movable filter 85a and the second movable filter 85b.

[0094] In this embodiment, the first transmittance distribution is a function Tx in the X-axis direction, which is expressed by a k-th degree equation (k is a natural number of 2 or more) with the coordinate in the X-axis direction as a variable. １ (x), and a third transmittance distribution T ３ (x, y) is the first transmittance distribution Tx in the X-axis direction １(x), and the relative positions of the first movable filter 85a and the fixed filter 85c can be changed in the Y-axis direction and the X-axis direction.

[0095] As a result, by moving the first movable filter 85a from the reference position in the X-axis direction, a composite transmittance distribution expressed by a k-1 order equation can be generated in the X-axis direction, and the illuminance distribution of the illumination light IL in the X-axis direction can be corrected by the composite transmittance distribution expressed by a k-1 order equation.

[0096] In this embodiment, a function Tx １ (x) includes terms of order k-1 or lower. As a result, as described with reference to FIGS. 8A and 8B, the transmittance range, which is the difference between the maximum transmittance and the minimum transmittance of the first movable filter 85a, can be reduced. This makes it possible to suppress a decrease in the illuminance of the illumination light IL caused by the filter unit 85.

[0097] The correction of the illuminance distribution of the illumination light IL by the filter unit 85 is performed at predetermined timings when the exposure apparatus 10 is installed, when the exposure apparatus 10 is maintained, and when the exposure apparatus 10 is in use. In this case, the illuminance distribution of the illumination light IL is measured, and the positions of the first movable filter 85a and the second movable filter 85b that will make the illuminance distribution of the illumination light IL uniform are calculated based on the measurement results, and the first movable filter 85a and the second movable filter 85b are moved to those positions. The positions of the first movable filter 85a and the second movable filter 85b may be moved manually or using an actuator such as a motor. This allows optimal adjustment for each of multiple illumination optical systems with different σ values ​​installed in the exposure apparatus. Furthermore, it is possible to measure the illuminance distribution at predetermined timings, calculate the positions of the movable filters, and perform optimal adjustments to accommodate changes in illuminance unevenness (non-uniformity of illuminance distribution) depending on the usage status of the exposure apparatus. Furthermore, even when the exposure area on the substrate P is deformed to match the pattern shapes of various masks, it is possible to suppress uneven illuminance across the entire illumination area, which is effective in suppressing uneven exposure, including in the joint areas of the multi-lens.

[0098] In the above embodiment, the first movable filter 85a has the function of correcting the illuminance distribution in the X-axis direction, but the second movable filter 85b may have the function of correcting the illuminance distribution in the X-axis direction. Also, a filter other than the first movable filter 85a and the second movable filter 85b may have the function of correcting the illuminance distribution in the X-axis direction.

[0099] In the above embodiment, the fixed filter 85c has a third transmittance distribution that is complementary to the first transmittance distribution of the first movable filter 85a and the second transmittance distribution of the second movable filter 85b in the Y-axis direction and complementary to the first transmittance distribution of the first movable filter 85a in the X-axis direction. However, a filter having a transmittance distribution complementary to the first transmittance distribution and a filter having a transmittance distribution complementary to the second transmittance distribution may be separately arranged. Also, a filter having a transmittance distribution complementary to the first transmittance distribution in the Y-axis direction and a filter having a transmittance distribution complementary to the first transmittance distribution in the X-axis direction may be separately arranged. Furthermore, the third transmittance distribution of the fixed filter 85c does not have to be complementary to the first transmittance distribution of the first movable filter 85a and the second transmittance distribution of the second movable filter 85b in the Y-axis direction, and does not have to be complementary to the first transmittance distribution of the first movable filter 85a in the X-axis direction.

[0100] Furthermore, in the above embodiment, the transmittance distribution in the X-axis direction of the second movable filter 85b is constant. However, the transmittance distribution in the X-axis direction may be formed according to a function expressed by a jth-order equation (j is a natural number of second or higher order) in which the coordinate in the X-axis direction is a variable.

[0101] Furthermore, in the above embodiment, the filter unit 85, among the elements constituting the illumination optical system 80, is disposed in a position closest to the mask MSK, but this is not limiting. The filter unit 85 may be disposed in any appropriate position on the optical path of the illumination optical system 80. Furthermore, instead of the mask MSK, a spatial light modulation element such as a digital micromirror device (DMD) in which a large number of micromirrors that are capable of minute displacement are regularly arranged may be used, and may be disposed in an appropriate position.

[0102] Furthermore, in the above embodiment, the fixed filter 85c does not move (is fixed) in the X-axis direction and the Y-axis direction, but the fixed filter 85c may be movable in at least one of the X-axis direction and the Y-axis direction.

[0103] Furthermore, according to the above embodiment, the filter unit 85 includes a plurality of filters arranged on the optical axis AX of the illumination optical system 80. The plurality of filters include a first movable filter 85 a, a second movable filter 85 b, and a fixed filter 85 c. The first movable filter 85 a has a first transmittance distribution that is non-uniform in the Y-axis direction intersecting the optical axis AX in the region where the illumination light IL is incident, the second movable filter 85 b has a second transmittance distribution that is non-uniform in the Y-axis direction that intersects with the optical axis AX in the region where the illumination light IL is incident and that is different from the first transmittance distribution, and the fixed filter 85 c has a third transmittance distribution that is non-uniform in the Y-axis direction and different from the first transmittance distribution and the second transmittance distribution in the region where the illumination light IL is incident. The filter unit 85 has a first composite transmittance distribution when the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c are each at a reference position in the Y-axis direction, a second composite transmittance distribution when the first movable filter 85a is at a position other than the reference position in the Y-axis direction and the second movable filter 85b and the fixed filter 85c are each at a reference position in the Y-axis direction, and a third composite transmittance distribution when the first movable filter 85a and the fixed filter 85c are each at a reference position in the Y-axis direction and the second movable filter 85b is at a position other than the reference position in the Y-axis direction. The first composite transmittance distribution has a transmittance within a predetermined range, the second composite transmittance distribution monotonically increases from one side in the Y-axis direction to the other side so that the transmittance is smaller than the lower limit of the predetermined range on one side in the Y-axis direction and larger than the upper limit of the predetermined range on the other side in the Y-axis direction, or monotonically decreases from one side in the Y-axis direction to the other side so that the transmittance is larger than the upper limit of the predetermined range on one side in the Y-axis direction and smaller than the lower limit of the predetermined range on the other side in the Y-axis direction, and the third composite transmittance distribution is convex toward higher transmittance so that the transmittance is smaller than the lower limit of the predetermined range on both sides in the Y-axis direction, or is convex toward lower transmittance so that the transmittance is larger than the upper limit of the predetermined range on both sides in the Y-axis direction.

[0104] Furthermore, in the above embodiment, the first movable filter 85a has a first transmittance distribution along the X-axis direction, which is perpendicular to the Y-axis direction, in the region where the illumination light IL is incident, which is non-uniform in the Y-axis direction; the second movable filter 85b has a second transmittance distribution along the X-axis direction, which is non-uniform in the Y-axis direction, in the region where the illumination light IL is incident; and the fixed filter 85c has a third transmittance distribution along the X-axis direction, which is non-uniform in the Y-axis direction, in the region where the illumination light IL is incident.

[0105] In the above embodiment, the first composite transmittance distribution is substantially constant, the second composite transmittance distribution is inclined, and the third composite transmittance distribution is curved.

[0106] In addition, in the above embodiment, the reference positions of the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c are positions in the Y-axis direction where the center of the first movable filter 85a, the center of the second movable filter 85b, and the center of the fixed filter 85c coincide with the optical axis AX.

[0107] In addition, in the above embodiment, the first movable filter 85a is movable in the Y-axis direction, the second movable filter 85b is movable in the Y-axis direction, and the fixed filter 85c is fixed at a reference position in the Y-axis direction.

[0108] In the above embodiment, the area where the illumination light IL is incident on each of the first movable filter 85a, the second movable filter 85b, and the fixed filter 85c is rectangular.

[0109] In addition, in the above embodiment, the difference between the upper and lower limits of the specified range is smaller than the difference between the maximum and minimum transmittances of the first transmittance distribution, smaller than the difference between the maximum and minimum transmittances of the second transmittance distribution, and smaller than the difference between the maximum and minimum transmittances of the third transmittance distribution.

[0110] Furthermore, in the above embodiment, the first transmittance distribution is convex toward higher transmittance or convex toward lower transmittance, the second transmittance distribution includes a first region that is convex toward higher transmittance and a second region that is convex toward lower transmittance, and the third transmittance distribution includes a region that is convex toward lower transmittance and corresponds to the first region, and a region that is convex toward higher transmittance and corresponds to the second region.

[0111] In the above embodiment, the filter unit 85 is arranged so that light from the filter unit 85 is incident on the mask MSK without passing through a lens.

[0112] Furthermore, according to the above embodiment, the illumination optical system 80 includes the fly-eye lens FEL arranged on the optical axis AX, and the filter unit 85 onto which the illumination light IL is incident via the fly-eye lens FEL.

[0113] Furthermore, according to the above embodiment, the exposure apparatus 10 is equipped with an illumination optical system 80a that illuminates the mask MSK, a projection optical unit 100a that irradiates the substrate with light from the illumination optical system 80a via the mask MSK, an illumination optical system 80b that is different from the illumination optical system 80a and that illuminates the mask MSK, and a projection optical unit 100b that is different from the projection optical unit 100a and that irradiates the substrate P with light from the illumination optical system 80b via the mask MSK, and successive exposures are performed by the projection optical unit 100a and the projection optical unit 100b while the substrate P is moved in a scanning direction corresponding to the X-axis direction.

[0114] In the above embodiment, the exposure apparatus 10 is equipped with an illumination optical system 80 that illuminates the mask MSK, and a projection optical system PL that irradiates the substrate P with light from the illumination optical system 80 via the mask MSK, and the projection optical system PL scans and exposes a first region of the substrate P while the substrate P is moved in a scanning direction corresponding to the X-axis direction, and then the projection optical system PL scans and exposes a second region of the substrate P that overlaps with part of the first region and is different from the first region while the substrate P is moved in a direction parallel to the scanning direction.

[0115] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this and can be modified in various ways without departing from the spirit of the present invention.

[0116] 10 exposure apparatus 80a to 80g illumination optical system 85 filter unit 85a first movable filter 85b second movable filter 85c fixed filter 100 projection optical unit 21 light source MSK mask PL projection optical system

Claims

1. A filter unit including a plurality of filters arranged on an optical axis of an illumination optical system that illuminates an illumination target surface, The plurality of filters include: a first filter having a first transmittance distribution; a second filter having a second transmittance distribution; Including, the first transmittance distribution is formed in a first direction of a Cartesian coordinate system in a plane orthogonal to an optical axis of the illumination optical system, according to a first function expressed by an n-th degree equation (n is a natural number of 2 or more) in which coordinates in the first direction are variables; a relative position between the first filter and the second filter is changeable at least in the first direction; Filter unit.

2. 2. The filter unit according to claim 1, wherein the second transmittance distribution is complementary to at least the first transmittance distribution in the first direction.

3. the first function has terms of order n-1 or less; The filter unit according to claim 2 .

4. the plurality of filters includes a third filter having a third transmittance distribution; the third transmittance distribution is formed in the first direction according to a second function expressed by an m-th degree equation (m is a natural number of 2 or more) in which coordinates in the first direction are variables, the second transmittance distribution is complementary to the first transmittance distribution and the third transmittance distribution in the first direction; a relative position between the second filter and the third filter is changeable in the first direction; The filter unit according to claim 1 .

5. the second function has terms of order m-1 or less, The filter unit according to claim 4.

6. m is greater than n, The filter unit according to claim 4.

7. the first transmittance distribution is formed in a second direction orthogonal to the first direction of the Cartesian coordinate system according to a third function expressed by a k-th degree equation (k is a natural number of 2 or more) in which coordinates in the second direction are variables, the second transmittance distribution is complementary to the first transmittance distribution in the second direction; a relative position between the first filter and the second filter is changeable in the first direction and the second direction; The filter unit according to claim 4.

8. the third function includes terms of order k-1 or less, The filter unit according to claim 7.

9. The plurality of filters include: a third filter having a third transmittance distribution; a fourth filter having a fourth transmittance distribution; Including, the third transmittance distribution is formed in the first direction according to a second function expressed by an m-th degree equation (m is a natural number of 2 or more) in which coordinates in the first direction are variables, the fourth transmittance distribution is complementary to the third transmittance distribution in the first direction; a relative position between the third filter and the fourth filter is changeable at least in the first direction; The filter unit according to claim 1 .

10. the plurality of filters includes a third filter having a third transmittance distribution; the third transmittance distribution is formed in a second direction orthogonal to the first direction of the Cartesian coordinate system according to a second function expressed by a k-th degree equation (k is a natural number of 2 or more) in which coordinates in the second direction are variables, the second transmittance distribution is complementary to the third transmittance distribution in the second direction; a relative position between the second filter and the third filter is changeable in the second direction; The filter unit according to claim 1 .

11. The plurality of filters include: a third filter having a third transmittance distribution; a fourth filter having a fourth transmittance distribution; Including, the third transmittance distribution is formed in a second direction orthogonal to the first direction of the Cartesian coordinate system according to a second function expressed by a k-th degree equation (k is a natural number of 2 or more) in which coordinates in the second direction are variables, the fourth transmittance distribution is complementary to the third transmittance distribution in the second direction; a relative position between the third filter and the fourth filter is changeable in the second direction; The filter unit according to claim 1 .

12. an optical integrator onto which light emitted from the light source is incident; A filter unit according to any one of claims 1 to 11; Equipped with The light emitted from the optical integrator is incident on the filter unit. Lighting unit.

13. A plurality of lighting units according to claim 12; a plurality of projection optical units corresponding to the plurality of illumination units, each projecting a pattern image of a mask illuminated by the plurality of illumination units onto a photosensitive substrate; Equipped with the plurality of projection optical units include a first projection optical unit and a second projection optical unit; an exposure area of ​​the first projection optical unit and an exposure area of ​​the second projection optical unit partially overlap each other; Exposure equipment.

14. The photosensitive substrate has at least one side length or diagonal length of 500 mm or more. The exposure apparatus according to claim 13.

15. An exposure method using the exposure apparatus according to claim 13, illuminating the mask with the plurality of illumination units; projecting the pattern image of the mask onto the photosensitive substrate using the projection optical unit; An exposure method comprising:

16. A filter unit including a plurality of filters arranged on an optical axis of an optical system, The plurality of filters include: a first filter having a first transmittance distribution; a second filter having a second transmittance distribution; Including, the first transmittance distribution is non-uniform in a first direction of a Cartesian coordinate system in a plane perpendicular to the optical axis of the optical system, the second transmittance distribution is non-uniform in the first direction; a relative position between the first filter and the second filter is changeable at least in the first direction; Filter unit.

17. The filter unit according to claim 16 , wherein a combined transmittance distribution of the plurality of filters is substantially constant in the first direction when the plurality of filters are in a reference position.

18. The plurality of filters includes a third filter having a third transmittance distribution, a relative position between the third filter and the second filter is changeable at least in the first direction; the third transmittance distribution is non-uniform in the first direction.

17. The filter unit of claim 16.

19. The first transmittance distribution follows a first function expressed by an n-th degree equation (n is a natural number of 2 or more) with coordinates in the first direction as variables, The third transmittance distribution is determined according to a third function expressed by a k-th degree equation (k is a natural number equal to or greater than 3) in which the coordinate in the first direction is a variable, The second transmittance distribution follows a second function expressed by an m-th degree equation (m is a natural number equal to or greater than n+k) in which the coordinate in the first direction is a variable.

19. The filter unit of claim 18.

20. the third function has terms of order m-1 or less; 20. The filter unit of claim 19.

21. an optical integrator onto which light emitted from the light source is incident; a filter unit according to any one of claims 16 to 20, into which light emitted from the optical integrator is incident; A lighting unit including:

22. a plurality of lighting units according to claim 21; a plurality of projection optical units corresponding to the plurality of illumination units, the plurality of projection optical units include a first projection optical unit and a second projection optical unit; an exposure area of ​​the first projection optical unit and an exposure area of ​​the second projection optical unit partially overlap each other; Exposure equipment.

23. The photosensitive substrate projected onto the plurality of projection optical units has at least one side length or diagonal length of 500 mm or more.

23. The exposure apparatus according to claim 22.

24. An exposure method using the exposure apparatus according to claim 22, illuminating a mask using the plurality of illumination units; projecting a pattern image of the mask onto a photosensitive substrate using the plurality of projection optical units; An exposure method comprising:

25. A filter unit including a plurality of filters arranged on an optical axis of an optical system, the plurality of filters include a first filter, a second filter, and a third filter; the first filter has a first transmittance distribution that is non-uniform in a first direction intersecting the optical axis in a region where illumination light is incident; the second filter has a second transmittance distribution that is non-uniform in the first direction and different from the first transmittance distribution in a region where the illumination light is incident; the third filter has a third transmittance distribution that is non-uniform in the first direction in a region where the illumination light is incident and that is different from the first transmittance distribution and the second transmittance distribution; The filter unit comprises: the first filter, the second filter, and the third filter each have a first composite transmittance distribution when they are at a reference position in the first direction; a second composite transmittance distribution when the first filter is at a position other than the reference position in the first direction and the second filter and the third filter are at the reference positions in the first direction, a third composite transmittance distribution when the first filter and the third filter are each at the reference position in the first direction and the second filter is at a position other than the reference position in the first direction; the first composite transmittance distribution has a transmittance within a predetermined range; the second composite transmittance distribution monotonically increases from one side to the other side in the first direction so that the transmittance is smaller than the lower limit of the predetermined range on one side in the first direction and larger than the upper limit of the predetermined range on the other side in the first direction, or monotonically decreases from one side to the other side in the first direction so that the transmittance is larger than the upper limit of the predetermined range on the one side in the first direction and smaller than the lower limit of the predetermined range on the other side in the first direction, the third composite transmittance distribution is convex toward a higher transmittance side so that the transmittance is smaller than the lower limit of the predetermined range on both the one side and the other side in the first direction, or is convex toward a lower transmittance side so that the transmittance is larger than the upper limit of the predetermined range on both the one side and the other side in the first direction. Filter unit.

26. the first filter has, in a region where the illumination light is incident, the first transmittance distribution that is non-uniform in the first direction along a second direction that is perpendicular to the first direction; the second filter has, in a region where the illumination light is incident, the second transmittance distribution along the second direction, which is non-uniform in the first direction; the third filter has the third transmittance distribution along the second direction in a region where the illumination light is incident, the third filter being non-uniform in the first direction; 26. The filter unit of claim 25.

27. the first composite transmittance distribution is substantially constant; the second composite transmittance distribution is tilted; the third composite transmittance distribution is curved; 27. A filter unit according to claim 25 or claim 26.

28. the reference positions of the first filter, the second filter, and the third filter are positions where a center of the first filter, a center of the second filter, and a center of the third filter coincide with the optical axis in the first direction, respectively; 27. A filter unit according to claim 25 or claim 26.

29. the first filter is movable in the first direction; the second filter is movable in the first direction; the third filter is fixed at the reference position in the first direction.

27. A filter unit according to claim 25 or claim 26.

30. the region of each of the first filter, the second filter, and the third filter is rectangular; 27. A filter unit according to claim 25 or claim 26.

31. a difference between the upper limit and the lower limit of the predetermined range is smaller than a difference between a maximum transmittance and a minimum transmittance of the first transmittance distribution, smaller than a difference between a maximum transmittance and a minimum transmittance of the second transmittance distribution, and smaller than a difference between a maximum transmittance and a minimum transmittance of the third transmittance distribution; 27. A filter unit according to claim 25 or claim 26.

32. the first transmittance distribution is convex toward a higher transmittance or convex toward a lower transmittance, the second transmittance distribution includes a first region that is convex toward a higher transmittance side and a second region that is convex toward a lower transmittance side, the third transmittance distribution includes a region that is convex toward a lower transmittance side and corresponds to the first region, and a region that is convex toward a higher transmittance side and corresponds to the second region, 27. A filter unit according to claim 25 or claim 26.

33. The filter unit is arranged so that light from the filter unit is incident on the mask without passing through a lens.

33. The filter unit of claim 32.

34. a fly-eye lens disposed on the optical axis; the filter unit according to claim 25 or 26, into which the illumination light is incident via the fly-eye lens; A lighting unit comprising:

35. a first illumination optical system, which is the illumination unit according to claim 34, for illuminating a mask; a first projection optical system that irradiates a substrate with light from the first illumination optical system via the mask; a second illumination optical system that is different from the first illumination optical system and that illuminates the mask; a second projection optical system different from the first projection optical system, which irradiates the substrate with light from the second illumination optical system via the mask; Equipped with performing continuous exposure by the first projection optical system and the second projection optical system while moving the substrate in a scanning direction corresponding to the second direction; Exposure equipment.

36. an illumination unit according to claim 34 for illuminating a mask; a projection optical system that irradiates a substrate with light from the illumination unit via the mask; Equipped with a first region of the substrate is scanned and exposed by the projection optical system while the substrate is moved in a scanning direction corresponding to a second direction orthogonal to the first direction, and then a second region of the substrate, which overlaps with a part of the first region and is different from the first region, is scanned and exposed by the projection optical system while the substrate is moved in a direction parallel to the scanning direction; Exposure equipment.

37. An illumination unit according to claim 34 for illuminating one of a mask or a spatial light modulator; a projection optical system that irradiates a substrate with light from the one of the mask and the spatial light modulation element; An exposure apparatus comprising: