Exposure head for exposure device, exposure device, and exposure method

Abstract

[Problem] In an exposure device equipped with an array of optical modulation elements such as a DMD, a segmented optical system adapted to high resolution of the pattern is provided. [Solution] An exposure device (10) is equipped with an exposure head (20), and the exposure head (20) is equipped with a projection optical system (25) including a DMD (22), a first imaging optical system (30), a splitting optical system (40), and a second imaging optical system (50). The splitting optical system (40) projects a pattern image divided by an incident plane located on the imaging plane of the first imaging optical system (30) into other scanning band regions B1 to B3. Then, a branching optical system (42) is configured so that the optical path lengths from the imaging plane of each divided pattern image to the projection areas TA1 to TA3 become equal to each other.

Description

Technology Field

[0001] The present invention relates to an exposure apparatus that projects a pattern onto a substrate or the like using an array of optical modulation elements such as a Digital Micro-mirror Device (DMD), and in particular, to a projection optical system that projects pattern light onto an exposure plane. Background Technology

[0002] In an exposure device equipped with a DMD, an array of optical modulators arranged in a matrix shape with movable mirrors is controlled, and light modulated by the array of optical modulators is projected onto a substrate as pattern light.

[0003] In an exposure apparatus, it is possible to divide pattern light and project it onto a substrate by using a splitting optical system (see Patent Document 1). Here, light reflected from an optical modulation element array is divided by a splitting optical system having an incident plane at the position of the imaging plane. Then, the divided plurality of pattern lights are projected into different scanning band regions according to the sub-scanning direction.

[0004] In addition, a split optical system is proposed that combines a prism having an incident plane at the position of the image plane with a reflective optical system (see Patent Document 2). In this case, the image position on the exposure plane of the split pattern is moved by moving a part of the reflective optical system in parallel or by rotating it. In addition, the image position can be adjusted (changed) in the same way by placing a pair of prisms that are relatively movable instead of the reflective optical system.

[0005] When a split optical system is placed in a projection optical system, it is necessary to focus the split pattern light on the exposure plane. For this reason, an optical member for adjusting the optical path length of the pattern light emitted from the split optical system is placed on the substrate side. Prior art literature

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-247711 [Patent Document 2] Japanese Patent Publication No. 2021-96300 The problem to be solved

[0007] With the increase in pattern resolution, a higher NA of the projection optical system is required. However, increasing the NA leads to a larger projection optical system. Since reflected light from optical modulation arrays such as DMDs spreads out as it travels, if the optical path length within the split optical system increases, the size of the split optical system itself also increases.

[0008] Meanwhile, the split optical system must be positioned between the imaging plane of the reflected light from the optical modulation element array and the incident plane of the imaging optical system installed below the split optical system, and there are constraints on the placement space.

[0009] Therefore, in an exposure device equipped with an array of optical modulation elements such as a DMD, it is required to configure a segmented optical system adapted to high resolution of the pattern. means of solving the problem

[0010] The exposure head for an exposure device according to the present invention comprises a projection optical system that divides light modulated in an array of optical modulation elements and forms a plurality of divided lights on an exposure surface. In the exposure device, light modulated in an array of optical modulation elements is divided, and a plurality of divided lights are formed on different scanning band regions according to the sub-scanning direction of the exposure surface.

[0011] The projection optical system comprises a split optical system having an incident plane at the position of the image plane of the light modulated in the optical modulation element array. Furthermore, the split optical system of the present invention aligns the optical path length from a predetermined image plane to an exposure plane for each of a plurality of split lights.

[0012] Here, "the optical path length from the imaging plane to the exposure plane for each of the multiple divided lights" refers to the optical path length to each exposure area (here, referred to as the divided exposure area) of each divided light, which is determined at the stage where the exposure head for the exposure device is embedded in the exposure device, without modulating or adjusting the optical path length of any divided light by a movable mirror such as an axis rotation or parallel translation.

[0013] In this sense, the split optical system of the present invention relates to at least an optical system for splitting light, and can be regarded as an optical system that does not include a movable mirror capable of changing the optical path length, or does not include an optical path length adjustment member. It can be said that the relative positional relationship of a plurality of split exposure areas on the exposure plane is predetermined.

[0014] In addition, the split optical system of the present invention, which does not include a movable mirror or an optical path length adjustment member, can be described as being configured as an optical system that aligns the optical path lengths so that the imaging positions on the exposure plane of a plurality of split lights are on the same plane.

[0015] The form of a splitting optical system is diverse, and it can be constructed using mirrors, prisms, or a combination thereof. For example, a splitting optical system can be configured to have multiple reflective surfaces that guide multiple split lights to the exposure plane from different paths. Additionally, multiple reflective surfaces are installed so that the optical path lengths from the imaging plane to the exposure plane are equal for each.

[0016] For example, the splitting optical system can be configured to have a pair of reflective surfaces that are in a parallel plane relationship and reflect the central splitting light. In this case, the optical path lengths can be aligned by determining the distance between and the position of the pair of reflective surfaces corresponding to the central splitting light to match the optical path lengths of the other splitting light.

[0017] The pair of reflective surfaces can be configured, for example, as the inner reflective surfaces of a pair of mirrors or a pair of prisms. When the pair of reflective surfaces is configured as the inner reflective surfaces of a pair of prisms, the split optical system can be configured to have a parallel planar plate interposed between the pair of prisms.

[0018] In the configuration of a split optical system equipped with a pair of reflective surfaces, the reflective surfaces can be configured such that, considering the diffusion of light from the incident surface of the split optical system downwards, the width of the reflective surface located below the image plane expands toward the lower part of the image plane.

[0019] The splitting optical system can be configured according to the number of splits (number of branches) of light. For example, the splitting optical system can split the light into odd numbers of patterns, i.e., 2n+1 (where n is an integer greater than or equal to 1), modulated by an optical modulation element array. In this case, the splitting optical system can be configured to form an image of the central split light at the position furthest from the optical axis of the projection optical system.

[0020] In addition, the splitting optical system can split the light modulated by the optical modulation element array into 2n pattern lights (where n is an integer greater than or equal to 1). In this case, the splitting optical system can be configured to split the light by excluding the light that is formed in a predetermined central area by installing a gap near the center of the incident plane.

[0021] An exposure method according to another embodiment of the present invention is an exposure method that exposes an exposure surface of a photographic body using light modulated in an array of light modulating elements, and divides the light modulated in the array of light modulating elements by a projection optical system and forms a plurality of divided lights in different scanning band regions according to the sub-scanning direction of the exposure surface, and aligns the light path lengths from the imaging surface to a plurality of divided exposure regions, the relative positional relationship on the exposure surface is predetermined, by means of a splitting optical system having an incident plane at the position of the imaging surface of the light modulated in the array of light modulating elements. Effects of the invention

[0022] According to the present invention, in an exposure apparatus equipped with an array of optical modulation elements such as a DMD, a segmented optical system adapted to high resolution of the pattern can be provided. Brief explanation of the drawing

[0023] [Fig. 1] This is a schematic perspective view of an exposure device of the first embodiment. [Fig. 2] This is a schematic diagram showing the internal configuration of an exposure head. [Fig. 3] This figure shows the divided area in the DMD according to the three divided patterns, and the position on the three divided patterns projected onto the exposure plane. [Fig. 4] This is a schematic perspective view of a segmented optical system. [Fig. 5] This is a schematic exploded perspective view of a segmented optical system. [Fig. 6] This is a schematic cross-sectional view of the central part of the split optical system. [Fig. 7] This is a perspective view showing a part of a reflective optical system that is a modified example of a branching optical system. [Fig. 8] This is a cross-sectional view of a reflective optical system, a modified example. [Fig. 9] This is a perspective view showing a reflective optical system that is a modified example of a branching optical system. [Fig. 10] This is a schematic perspective view of a split optical system in a second embodiment. [Fig. 11] This is a schematic cross-sectional view of the central part of the split optical system in the second embodiment. [Fig. 12] This is a figure showing the positions on the five divided patterns projected onto the exposure plane in the second embodiment. [Fig. 13] This is a schematic perspective view of a split optical system in the third embodiment. [Fig. 14] This is a figure showing the positions on the six divided patterns projected onto the exposure plane in the third embodiment. Specific details for implementing the invention

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of an exposure apparatus according to a first embodiment.

[0025] The exposure device (10) is a maskless exposure device that directly projects pattern light onto a substrate W coated or mounted with a photosensitive material such as photoresist, and is equipped with a gate-type structure (12) and a base (14). The substrate W is mounted on a drawing table (15) supported by the base (14).

[0026] The drawing table (15) can be moved in the main scanning direction (hereinafter also referred to as the X direction) and the secondary scanning direction (hereinafter also referred to as the Y direction) by means of a stage driving mechanism (not shown). For the drawing table (15), mutually orthogonal XYZ coordinate systems are defined.

[0027] A light source unit (16) is installed in a gate-type structure (12) arranged to cross the base (14). The light source unit (16) is composed of a mercury lamp, an LED, or a laser diode, etc. Also, a plurality of exposure heads (20) (here, two) are installed side by side at a predetermined interval in the base (14). A pattern is projected onto the substrate W by an exposure operation by the exposure heads (20).

[0028] FIG. 2 is a schematic diagram showing the internal configuration of an exposure head (20).

[0029] The exposure head (20) is equipped with a Digital Micro-mirror Device (DMD) (22) and a projection optical system (25). Illumination light irradiated from the light source unit (16) is guided to the DMD (22) through the illumination optical system (17). The DMD (22) can be configured as a device in which micro-mirrors of a size of several μm to tens of μm are arranged in a two-dimensional matrix shape.

[0030] In the DMD (22), each micromirror is selectively controlled ON / OFF based on a control signal (exposure data) stored in a memory cell. Light reflected from the ON micromirror, i.e., modulated light, is guided to a projection optical system (25) through a mirror (not shown).

[0031] The projection optical system (25) is an optical system that forms a pattern light onto the exposure surface of the substrate W, and is equipped with a first forming optical system (30), a split optical system (40), and a second forming optical system (50). The first forming optical system (30) forms the light modulated by the DMD (22) onto the forming surface (hereinafter also referred to as the first forming surface) at the focal position, and at the same time magnifies the entire pattern image by a predetermined magnification.

[0032] The splitting optical system (40) splits the pattern light formed on the first imaging plane into a plurality of pattern lights. Here, the splitting optical system (40) branches the pattern light into three on the first imaging plane. In other words, the entire pattern image is divided into three pattern images (hereinafter referred to as split pattern images). The second imaging optical system (50) forms the three pattern lights (hereinafter also referred to as split lights) formed by the splitting optical system (40) on the exposure plane of the substrate W.

[0033] The split optical system (40) can be considered as an optical system embedded in the second imaging optical system (50). The imaging plane at the front focal position of the second imaging optical system (50) coincides with the imaging plane (focal position) of the first imaging optical system (30), and the imaging plane at the rear focal position coincides with the exposure plane of the substrate W.

[0034] The exposure head (20) is positioned at a small angle of inclination with respect to the main projection direction (X direction). By moving the drawing table (15) along the -X direction, as the substrate W moves, the projection area (exposure area) by the DMD (22) moves relative to the main projection direction (+X direction). Then, an exposure operation that irradiates pattern light according to the position of the projection area is executed according to a predetermined exposure pitch.

[0035] Here, a multi-exposure (overlap exposure) operation is performed according to the step-and-repeat method or the continuous movement method. When scanning along the X direction is finished, the drawing table (15) is moved in the sub-scanning direction and the drawing table (15) is moved back and forth. By doing so, a pattern is formed over the entire substrate W.

[0036] FIG. 3 is a figure showing the segmented regions in the DMD according to the three segmented patterns, and the positions on the three segmented patterns projected onto the exposure plane. Using FIG. 3, the segmentation and projection positions on the patterns will be explained.

[0037] As shown in FIG. 3, the reflective surface of the DMD (22) is defined with three divided portions DM1, DM2, and DM3 (hereinafter referred to as divided portions) along the transverse direction corresponding to the main direction (X direction). The pattern image of the entire DMD (22) is projected to different positions for each divided portion DM1, DM2, and DM3 by the divided optical system (40).

[0038] The three divided pattern images MP1, MP2, and MP3 formed by the divided optical system (40) are projected onto different scanning band regions B1 to B3 according to the sub-scanning direction Y on the exposure plane of the substrate W. The central divided pattern image MP2 formed on the first imaging plane FS, that is, the incident plane of the divided optical system (40), is projected onto scanning band region B1. Also, the divided pattern image MP1 on the left is projected onto scanning band region B2, and the divided pattern image MP3 on the right is projected onto scanning band region B3. Additionally, it is acceptable to project the three divided pattern images MP1, MP2, and MP3 while overlapping parts of each other.

[0039] The split optical system (40) enables simultaneous pattern formation across consecutive scanning band regions B1 to B3 during the exposure operation. In the split regions DM1, DM2, and DM3 of the DMD (22), each micromirror is controlled ON / OFF based on the drawing data of the pattern to be formed in the respective scanning band regions B1, B2, and B3.

[0040] During the exposure operation, projection areas (divided exposure areas) TA1, TA2, and TA3, in which MP1, MP2, and MP3 are formed on three divided patterns, are separated from each other by a predetermined distance L along the projection direction (X direction). The relative positional relationship of projection areas TA1, TA2, and TA3, that is, the distance interval between them along the X and Y directions, is predetermined. Here, projection area TA3 corresponds to the leading projection position, and projection areas TA2 and TA1 pass through the same X-coordinate position with a predetermined time delay. A control unit (not shown) of the exposure device (10) performs exposure operation control according to the positions of projection areas TA1, TA2, and TA3. Furthermore, regarding data processing during the exposure operation, it is possible to apply data processing such as that described in Patent Document 1, and a detailed description is omitted here.

[0041] In this embodiment, the splitting optical system (40) splits the light modulated by the DMD (22) into three pattern lights and branches the split lights to form images in scanning band areas B1 to B3, respectively. At this time, the split pattern light in the central part is formed in scanning band area B1, which is furthest from the optical axis C of the projection optical system (25). In addition, the splitting optical system (40) aligns the optical path lengths from the imaging plane (first imaging plane) FS of the three split pattern lights to the projection areas TA1 to TA3. That is, each split light passes through a different path and forms an image on a different scanning band, and the optical path lengths of each split light become equal. In addition, each reflective surface of the splitting optical system (40) is installed so that the optical path lengths from the first imaging plane FS to the projection areas TA1 to TA3 become equal.

[0042] FIG. 4 is a schematic perspective view of a split optical system (40). FIG. 5 is a schematic exploded perspective view of a split optical system (40). FIG. 6 is a schematic cross-sectional view of the central part of the split optical system (40). Using FIG. 4 to 6, the configuration of the split optical system (40) will be explained.

[0043] As described above, the incident plane MP of the split optical system (40) is located at the position of the first image plane FS along the optical axis C, and the split optical system (40) divides the entire pattern image of the DMD (22) into three split pattern images MP1 to PM3 at the incident plane MP. In addition, the split optical system (40) is equipped with an optical system (hereinafter referred to as a split optical system) (42) that propels the light of the split pattern image MP2 in the central part toward the projection area TA2, and optical systems (hereinafter referred to as split optical systems) (46, 48) that propel the light of the split pattern images MP2 and PM3 on both sides toward the projection areas TA2 and TA3, respectively.

[0044] The branching optical system (42) and the branching optical system (46, 48) are configured as prisms. As shown in FIG. 5, the branching optical system (42) is composed of a triangular prism-shaped prism (43) and a prism (44) in which the cross-section along the optical axis C is trapezoidal, the side along the main scanning direction is triangular, and the side along the secondary scanning direction is trapezoidal.

[0045] As shown in FIG. 6, the side surface (43S) of the prism (43) and the side surface (44S) of the prism (44) are in contact with each other over the entire surface. Additionally, the prism (44) has an incident surface MP02 where reflected light is formed according to the divided area DM2 of the DMD (22), and the inner surface of the prism (44R) located below the incident surface MP02 is configured as a reflective surface. Additionally, the inner surface (43R) of the prism (43) is configured as a reflective surface. The reflective surfaces (43R, 44R) are in a parallel plane relationship with each other.

[0046] The branching optical system (46) is composed of two prisms (46A, 46B). Prism (46A) has a pair of reflective surfaces (47R1, 47R2) that are in a plane-like relationship with each other. One side of the reflective surface (47R1) extends along the plane of incidence MP and defines a boundary line R1 that divides the pattern image in a direction along the sub-scanning direction (Y direction). Prism (46B), which is in contact with the bottom surface of prism (46A), has a pair of reflective surfaces (47R3, 47R4) that are in a plane-like relationship with each other.

[0047] The branching optical system (48) is also composed of a prism (48A) and a prism (48B) having an incident plane MP03 in which the boundary line R2 of the pattern division is defined, just like the branching optical system (46). In addition, the prisms (48A, 48B) each have a pair of reflective surfaces, just like the prisms (46A, 46B). Furthermore, regarding the configuration of the pair of reflective surfaces of the branching optical system (46, 48), the configuration is the same as that of the pair of reflective optical systems described in Patent Document 1, and a detailed description is omitted.

[0048] In this embodiment, the splitting optical system (40) is configured such that the optical path lengths from the incident planes MP01, MP02, and MP03 of each of the splitting optical systems (42, 46, 48) to the exposure plane are equal to each other. Specifically, the prisms (43, 44) of the splitting optical system (42) are configured such that the optical path length PL2 to the projection area TA2 of the splitting light incident on the incident plane MP02 of the splitting optical system (42) is equal to the optical path lengths PL1 and PL3 to the projection areas TA1 and TA3 of the splitting light incident on the incident planes MP01 and MP03 of the splitting optical system (46, 48).

[0049] To explain more specifically, the distance between the reflective surfaces (43R, 44R) of the branching optical system (42), i.e., the thickness of the prisms (43, 44), is determined so that the optical path length PL2 becomes equal to the optical path lengths PL1 and PL3. In addition, the position of the reflective surfaces (43R, 44R), i.e., the angle of inclination (reflection angle), is determined. For example, the optical path length PL can be adjusted by configuring the prisms (43, 44) with the position of the reflective surfaces (43R, 44R) adjusted (see symbol AY in FIG. 6).

[0050] As described above, the projection areas TA1, TA2, and TA3 of the three split lights have a predetermined relative positional relationship, and the distance between them according to the main projection direction and the secondary projection direction is constant. Since the optical path lengths PL1 to PL3 are the same, an optical member for individually adjusting the optical path for each split light is not placed below the branching optical system (42, 46, 48).

[0051] As described above, in this embodiment, the exposure head (20) is equipped with a projection optical system (25) including a DMD (22), a first imaging optical system (30), a splitting optical system (40), and a second imaging optical system (50). The splitting optical system (40) projects a pattern image divided by an incident plane located on the imaging plane of the first imaging optical system (30) into different scanning band regions B1 to B3. Then, a branching optical system (42) is configured so that the optical path lengths from the imaging plane of each divided pattern image to the projection areas TA1 to TA3 become equal to each other. By configuring a compact split optical system (40) along the optical axis C direction of the projection optical system (25), the projection optical system (25) becomes larger for high NA, and even if there is a constraint on the space between the first image plane FS of the first image optical system (30) and the incident plane of the second image optical system (50), the split optical system (40) can be arranged.

[0052] The split optical system (40) described above is composed of a split optical system (42, 46, 48) each composed of a prism. However, it is also possible to compose it with a mirror instead of a prism.

[0053] FIG. 7 is a perspective view showing a part of a reflective optical system that is a substitute and modified example of the branching optical system (42). FIG. 8 is a cross-sectional view of the reflective optical system that is a modified example. FIG. 9 is a perspective view showing a reflective optical system that is a substitute and modified example of the branching optical system (46).

[0054] As shown in FIG. 8, the branching optical system (42') is composed of a pair of mirrors (43'R, 44'R) that are in a plane-like relationship with each other. The distance between them and their positions are the same as those of the branching optical system (42) described above, and the optical path lengths L1, L2, and L3 are set to be equal to each other.

[0055] As shown in FIG. 9, the branching optical system (46') is composed of a pair of mirrors (47'R1, 47'R2) that are in a plane-to-plane relationship with each other, and a pair of mirrors (47'R3, 47'R4) that are in a plane-to-plane relationship with each other. The pair of mirrors (47'R1, 47'R2) correspond to the pair of reflective surfaces (47R1, 47R2) of the branching optical system (46) described above, and the pair of mirrors (47'R3, 47'R4) correspond to the pair of reflective surfaces (47R3, 47R4) of the branching optical system (46) described above. The branching optical system (not shown here) on the opposite side of the branching optical system (42') is also composed of two mirrors in the same way.

[0056] FIG. 7 shows one mirror (44'R) in the branching optical system (42'). The mirror (44'R) is extended downwards in size (width) to account for the diffusion of the split light incident from the first imaging plane FS.

[0057] By configuring a split optical system using a branching optical system composed of such mirrors, changes in optical path length due to differences in wavelength do not occur. Therefore, it can be adapted to light sources that irradiate multi-band light.

[0058] Next, using FIGS. 10 to 12, an exposure apparatus of the second embodiment will be described. In the second embodiment, light modulated by a DMD is divided into five pattern lights and projected.

[0059] FIG. 10 is a schematic perspective view of a split optical system in a second embodiment. FIG. 11 is a schematic cross-sectional view of the central portion of the split optical system in a second embodiment.

[0060] The splitting optical system (140) is equipped with a prism (150) and a reflecting optical system (160). At the incident plane MP, which is located at the same position as the first image plane FS, the entire pattern image of the DMD (22) is divided into five pattern images. The branching optical system (142) is an optical system that branches the light of the divided pattern image in its central part, and is equipped with a prism (143) and a prism (144) having the same shape as the first embodiment, and further equipped with a parallel plane plate (145). A part of the prism (143) is embedded in the prism (150).

[0061] As shown in FIG. 11, the prisms (143, 144) each have reflective surfaces (143R, 144R) that are in a plane relationship parallel to each other. Also, a parallel plane plate (145) is interposed between the prisms (143, 144) and is in contact with the side surfaces (143S, 144S) of the prisms (143, 144).

[0062] FIG. 12 is a figure showing the positions on five divided patterns projected onto the exposure plane in the second embodiment.

[0063] As shown in FIG. 12, MP'1 to MP'5 on the five segmented patterns are each projected onto different scanning band regions B1 to B5. The relative positional relationships of the projection regions TA'1 to TA'5 of MP'1 to MP'5 on the five segmented patterns are predetermined.

[0064] MP'3 on the central part of the divided pattern is projected onto the scanning band area B1 furthest from the optical axis C of the projection optical system (25). Then, as in the first embodiment, the distance spacing, position, and thickness T of the parallel plane plate (see FIG. 12) of the reflective surfaces (143R, 144R) are determined so that the optical path lengths from the incident plane MP (first imaging plane FS) to the projection areas TA'1 to TA'5 of the five divided patterns become equal to each other. In particular, in the second embodiment, the optical path length PL' is adjusted by adjusting the thickness T of the parallel plane plate (145).

[0065] In addition, the configuration of the part excluding the branching optical system (142) of the prism (150) and the configuration of the reflecting optical system (160) can be configured by the prism and mirror pair shown in Patent Document 2, and a detailed description thereof is omitted.

[0066] In this way, by projecting MP'1 to MP'5 on five divided patterns onto consecutive scanning band regions B1 to B5, it is possible to perform simultaneous exposure with a wider exposure width, thereby improving throughput even for large substrates. In addition, since optical members for adjusting the optical path length are not required, a compact divided optical system can be constructed.

[0067] Next, using FIGS. 13 and 14, an exposure apparatus of the third embodiment will be described. In the third embodiment, light modulated by a DMD is divided into six pattern lights and projected.

[0068] FIG. 13 is a schematic perspective view of a split optical system in a third embodiment. The split optical system (240) is provided with a prism (250), a reflection optical system not shown located below it, and a branching optical system (242, 242'). However, only the prism (244, 244') embedded in the prism (250) is shown here. Furthermore, regarding the configuration of the prism (250) excluding the branching optical system (242, 242') and the reflection optical system not shown, it is possible to apply the configuration of the prism and reflection optical system described in Patent Document 2, as in the second embodiment.

[0069] The prism (244, 244') has the same shape as the prism (44) of the first embodiment, and also has an unillustrated triangular prism shaped like a prism (44) of the first embodiment, and furthermore has an unillustrated parallel flat plate interposed in between, just like the first embodiment.

[0070] Prisms (244, 244') are arranged with a gap of a predetermined distance GS according to the direction X of the main prism. And, the inner reflective surface located below the incident surfaces MP03 and MP04 of the prisms (244, 244') expands its size (width) downwards.

[0071] The prisms (244, 244') are arranged so that their directions are opposite to each other with respect to the auxiliary scanning direction. Therefore, the direction of propagation of the split light in the branching optical system (242, 242') is opposite to each other. Meanwhile, the optical path lengths are the same. The cross-section of each of the branching optical system (242, 242') has the same cross-sectional shape as in the second embodiment.

[0072] As in the first and second embodiments, the distance interval and position of the reflective surfaces in a parallel plane relationship and the thickness of the parallel plane plates are determined so that the optical path length of the branching optical system (242, 242') becomes the same as the optical path length on a different split pattern. In addition, in order to install a gap of a predetermined distance interval GS in the central part of the splitting optical system (240), in the exposure process, it is acceptable to set OFF data for the DMD area corresponding to that part.

[0073] FIG. 14 is a figure showing the positions on the six divided patterns projected onto the exposure plane in the third embodiment.

[0074] As shown in FIG. 14, the segmented pattern MP''3 and MP''4, which are close to the center, are projected into scanning band regions B1 and B6, which are furthest from the optical axis C of the projection optical system (25). Then, the segmented pattern MP''1, MP''2, MP''5, and MP''6 on both sides are projected into scanning band regions B2 to B5, respectively. Regarding the projection areas TA''1 to TA''6 of the segmented pattern MP''1 to MP''6, their relative positional relationships are predetermined.

[0075] In this way, according to the third embodiment, light modulated by the DMD can be divided into six divided lights and projected onto the substrate W. By doing so, throughput can be further improved while forming a compact divided optical system.

[0076] In the second and third embodiments, the splitting optical system is configured with prisms, but it may also be configured with a pair of mirrors as in the modified example of the first embodiment. Furthermore, it is not limited to 3 divisions or 5 divisions, and it is possible to configure a splitting optical system that projects an odd number of divided lights. In addition, it is possible to configure a splitting optical system that projects an even number of divided lights other than 6 divisions. Explanation of the symbols

[0077] 10 Exposure device 20 exposure heads 25 Projection optical system 30 First imaging optical system 40-segment optical system 50 Second imaging optical system FS 1st phase plane (phase plane)

Claims

Claim 1 An exposure head for an exposure device, characterized in that it comprises a projection optical system that divides light modulated in an optical modulation element array and forms a plurality of divided lights on an exposure plane, wherein the projection optical system comprises a splitting optical system having an incident plane that coincides with the formation plane of the light modulated in the optical modulation element array, wherein the splitting optical system divides the light modulated in the optical modulation element array at the incident plane to generate the plurality of divided lights, and wherein the splitting optical system aligns the optical path length from the formation plane to the exposure plane determined for each of the plurality of divided lights. Claim 2 An exposure head for an exposure device according to claim 1, wherein the split optical system has a plurality of reflective surfaces that guide the plurality of split lights to the exposure surface from different paths, and the plurality of reflective surfaces are installed such that the optical path lengths from the imaging surface to the exposure surface of the plurality of split lights are each equal. Claim 3 An exposure head for an exposure device according to claim 1, wherein the split optical system has a pair of reflective surfaces that are in a parallel plane relationship and reflect the central split light, and the distance between the pair of reflective surfaces and their positions are determined according to the optical path length of the other split light. Claim 4 An exposure head for an exposure device, characterized in that, in paragraph 3, the width of the reflective surface located below the image plane is expanded toward the downward direction of the image plane. Claim 5 An exposure head for an exposure device, characterized in that, in paragraph 3, a pair of reflective surfaces is configured as the inner reflective surfaces of a pair of mirrors or a pair of prisms. Claim 6 An exposure head for an exposure device according to claim 1, wherein the splitting optical system splits the light modulated in the optical modulation element array into 2n+1 pattern lights (where n is an integer greater than or equal to 1), and the splitting optical system forms an image of the central split light at the position furthest from the optical axis of the projection optical system on the exposure plane. Claim 7 An exposure head for an exposure device according to claim 1, characterized in that the split optical system divides the light modulated by the optical modulation element array into 2n pattern lights (where n is an integer greater than or equal to 1), excluding the light that forms an image in a predetermined central area. Claim 8 An exposure device characterized by having an exposure head for an exposure device described in any one of claims 1 to 7, dividing light modulated in the optical modulation element array, and forming a plurality of divided lights in different scanning band regions according to the sub-scanning direction of the exposure surface. Claim 9 An exposure method for exposing an exposure surface of a photographic body using light modulated in an array of light modulating elements, wherein the light modulated in the array of light modulating elements is divided by a projection optical system and a plurality of divided lights are formed in different scanning band regions according to the sub-scanning direction of the exposure surface, wherein the light modulated in the array of light modulating elements is divided at the incident surface by a splitting optical system having an incident surface that corresponds to the position of the formation surface of the light modulated in the array of light modulating elements to generate the plurality of divided lights, and simultaneously, by the splitting optical system, the light modulated in the array of light modulating elements is aligned at the incident surface to a plurality of divided exposure regions whose relative positional relationship on the exposure surface is predetermined.

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