Exposure head and exposure apparatus for exposure equipment

Abstract

To provide an exposure device with an image segmentation optical system that facilitates throughput improvement.SOLUTION: An exposure device 10 has a first imaging optical system 25, an image segmentation optical system 30, and a second imaging optical system 26. The image segmentation optical system 30 has a prism 32 and a reflection optical system 34. The reflection optical system 34 comprises a mirror pair 34A, 34B, a mirror pair 34C, 34D, a mirror pair 34E, 34F, and a mirror pair 34G, 34H, each of which comprises Galvano mirrors.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a maskless exposure apparatus that directly draws a pattern by an optical modulation element array such as a DMD (Digital Micro-mirror Device), and particularly relates to an optical system that projects a pattern image onto an exposure surface.

Background Art

[0002] In a maskless exposure apparatus equipped with a DMD, it is possible to divide the pattern light reflected by the DMD and project a plurality of divided pattern images along the sub-scanning direction. For example, an exposure apparatus equipped with a splitting optical system having a pair of reflecting optical systems is known (see Patent Document 1). In that case, a pair of mirrors in a parallel plane relationship are arranged by the number of divisions, and the mirrors are arranged so as not to intersect the imaging surface (conjugate surface) that becomes the image splitting surface, and a divided pattern image is formed.

[0003] In an exposure apparatus equipped with such a splitting optical system, the divided pattern images are projected onto the exposure surface so as to be spaced apart from each other along the main scanning direction. Therefore, in order to effectively execute the raster data generation process for each scanning band (scanning region) and the exposure data generation process for the optical modulation element array, based on the projection position of a specific divided pattern image, from a series of raster data sequentially generated according to each scanning band, the raster data corresponding to a series of divided pattern images is extracted and integrated to generate exposure data (see Patent Document 2).

[0004] On the other hand, as a splitting optical system that forms a large number of divided pattern images, a splitting optical system is known in which a pair of mirrors in a parallel plane relationship are prepared by the number of divisions and the mirrors are arranged so as to intersect the imaging surface (conjugate surface) (see Patent Document 3). In that case, the splitting mirrors are inclined with respect to the conjugate surface so as to be spaced apart from each other in the main scanning direction and the sub-scanning direction, and are arranged so as to intersect.

[0005] Furthermore, maskless exposure apparatuses are also known that include a split optical system (see Patent Document 4) equipped with multiple triangular prism-shaped optical elements each having a different inclination angle with respect to the optical axis of the projection optical system, or a split optical system (see Patent Document 5) that splits the light reflected by the DMD into two using two mirrors. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5881314 [Patent Document 2] Patent No. 5881313 [Patent Document 3] Patent No. 6590638 [Patent Document 4] Japanese Patent Publication No. 2014-92707 [Patent Document 5] Japanese Patent Publication No. 2009-87995 [Overview of the project] [Problems that the invention aims to solve]

[0007] When it is necessary to form a large number of segmented pattern images (for example, a four-segmented pattern image) and to project clear segmented pattern images onto an exposure surface without insufficient light, it is conceivable to construct a segmentation optical system that combines the above-mentioned Patent Documents 1 and 3. Even in such cases, it is desirable to construct an image segmentation optical system that enables raster data generation processing and exposure data generation processing as shown in Patent Document 2, thereby facilitating improved throughput. [Means for solving the problem]

[0008] The exposure head for an exposure apparatus of the present invention comprises an optical modulation element array in which a plurality of optical modulation elements are arranged in a two-dimensional array, and a projection optical system that images the light reflected by the optical modulation element array onto the exposure surface of the object to be drawn, wherein the projection optical system comprises a first optical system that images the light of the pattern image reflected by the optical modulation element array onto a first imaging surface, and the pattern image formed on the first imaging surfaceDivide The system comprises an image division optical system that forms multiple divided pattern images, and a second optical system that focuses the light from the multiple divided pattern images onto the exposure surface. The splitting optical system comprises a plurality of pairs of splitting mirrors that split a pattern image formed on a first imaging surface such that a plurality of split pattern images are projected onto the exposure surface at positions separated from each other by a predetermined distance with respect to the main scanning direction and the sub-scanning direction, the plurality of pairs of splitting mirrors being inclined and intersecting with respect to the first imaging surface and in a parallel planar relationship, a reflective optical system that moves the light of the plurality of split pattern images on the exposure surface, and an optical path length modulating optical member that adjusts the optical path length of the light of the split pattern images. The reflective optical system comprises a plurality of pairs of mirrors that are in a parallel plane relationship with respect to each other, and at least one mirror in each pair of mirrors rotates or translates on an axis according to the projection positions of a predetermined plurality of segmented pattern images.

[0009] Mirror pairs can be configured in various ways. For example, a rotatable mirror pair can be configured with multiple mirror pairs, each consisting of a pair of galvanometer mirrors that rotate on an axis while maintaining a parallel plane relationship. Alternatively, a mirror pair that moves in translation can be configured such that one mirror in each mirror pair moves (relatively) along a direction perpendicular to its reflective surface. In either configuration, the segmented pattern image can be moved in a predetermined direction, such as a direction inclined with respect to the main scanning direction or the sub-scanning direction. Alternatively, one mirror in each mirror pair can be configured to rotate on an axis.

[0010] With such an image splitting optical system, a pattern image formed by light reflected by an array of optical modulation elements can be split, and multiple split pattern images can be formed so that they are arranged at predetermined intervals along the main scanning direction and have different positions along the sub-scanning direction. For example, in an exposure apparatus, if there is an exposure operation processing unit that converts pattern data, which is vector data, into raster data and controls each optical modulation element according to the raster data, the exposure operation processing unit may include a raster data generation unit that sets the position of one of the multiple partial projection areas along the main scanning direction as a common reference position among the multiple partial projection areas formed by the multiple split pattern images, which move relative to each other along the multiple scanning bands, and generates multiple raster data for the multiple scanning bands in accordance with that reference position, and an exposure data generation unit that extracts and integrates raster data corresponding to the positions of the multiple partial projection areas from a series of multiple raster data sequentially generated during scanning, and generates exposure data for the entire array of optical modulation elements.

[0011] For example, the exposure data generation unit has multiple memories in which multiple raster data are temporarily stored, each of which is composed of a buffer memory, each having a different memory capacity based on the distance interval between multiple partial projection areas, and multiple raster data corresponding to a reference position are input to the multiple memories simultaneously, while multiple raster data corresponding to the positions of multiple partial projection areas are output from each of the multiple memories. The exposure data generation unit has multiple FIFO-type buffer memories, each of which has a different memory size based on the distance interval along the main scanning direction from the reference position of each of the multiple partial projection areas.

[0012] The system may further include an imaging unit that captures the projection position of the segmented pattern image formed by the image segmentation optical system. Alternatively, it may include an optical path length modulation optical member that adjusts the optical path length of the segmented pattern image formed by the image segmentation optical system. [Effects of the Invention]

[0013] According to the present invention, an image splitting optical system that facilitates the improvement of throughput can be configured. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic perspective view of the exposure apparatus according to this embodiment. [Figure 2] This diagram schematically shows the internal structure of an exposure head. [Figure 3] This figure shows the configuration of the image splitting optical system 30. [Figure 4] This diagram shows the configuration of a mirror pair in a reflective optical system. [Figure 5] This figure shows the reflective surface in DMD22. [Figure 6] This diagram shows the projection position of the segmented pattern image. [Figure 7] This is a block diagram of the exposure apparatus.

Best Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a perspective view schematically showing the exposure apparatus according to the present embodiment.

[0017] The exposure apparatus 10 is a maskless exposure apparatus that directly irradiates a substrate W coated (or attached) with a photosensitive material such as photoresist with pattern light, and includes a gate-shaped structure 12 and a base 14. An X-Y stage drive mechanism 56 that supports a drawing table 18 is mounted on the base 14, and the substrate W is placed on the drawing table 18.

[0018] The gate-shaped structure 12 is provided with light sources 20a and 20b, and exposure heads 201 and 202 for pattern formation are arranged side by side above the substrate W. The exposure head 201 includes a DMD (Digital Micro-mirror Device) and a projection optical system (not shown here). Based on the light emitted from the light source 20a, a pattern image is projected onto the substrate W. The exposure head 202 has the same configuration, and projects a pattern image by the light of the light source 20b.

[0019] The rectangular substrate W is a substrate for an electronic circuit such as a printed circuit board, a dry film, or a glass substrate, and is mounted on the drawing table 18 in the state of blanks that have been subjected to pre-baking treatment, coating / attachment treatment of a photosensitive material, etc. An X-Y-Z coordinate system orthogonal to each other is defined for the substrate W (drawing table 18), and the drawing table 18 is movable along the X and Y directions, and is further rotatable around the Z axis. Here, the X direction is defined as the main scanning direction, and the Y direction is defined as the sub-scanning direction.

[0020] The exposure apparatus 10 includes a drawing control unit (not shown here) that controls the exposure operation. A monitor, keyboard, etc. (not shown here) are connected to the drawing control unit, and settings related to the drawing process are performed according to the operator's input. The CCD 19 provided on the protrusion 31 detects the deformation state of the substrate W, and the exposure operation is performed after the alignment is adjusted.

[0021] Figure 2 is a schematic diagram showing the internal configuration of the exposure head 201. The exposure head 202 has a similar internal configuration.

[0022] The illumination light emitted from light sources 20a and 20b shown in Figure 1 is guided to the DMD22 via an illumination optical system (not shown). The DMD22 is an optical modulation device in which tiny rectangular micromirrors ranging from a few micrometers to tens of micrometers in size are arranged in a two-dimensional matrix, and is composed of, for example, 1024 × 768 micromirrors.

[0023] In the DMD22, each micromirror is selectively controlled ON / OFF based on control signals (exposure data) stored in the memory cell. The light reflected by the ON micromirror is a luminous beam corresponding to the pattern to be projected, and is guided to the projection optical system 24 via a mirror (not shown).

[0024] The projection optical system 24 comprises a first imaging optical system 25, a second imaging optical system 26, and an image splitting optical system 30, and images the light from the DMD 22 onto the exposure surface of the substrate W. The first imaging optical system 25 images the light from the DMD 22 according to the pattern onto the imaging surface CS (first imaging surface) at the focal position, and magnifies the entire pattern image at a predetermined magnification.

[0025] The image splitting optical system 30 divides the pattern image formed on the imaging surface of the first imaging optical system 25 into multiple parts. Here, it forms a pattern image divided into four parts (hereinafter referred to as the split pattern image). The light from the split pattern image formed by the image splitting optical system 30 is then imaged onto the exposure surface of the substrate W by the second imaging optical system 26.

[0026] The imaging plane at the front focal position of the second imaging optical system 26 coincides with the imaging plane (focal position) of the first imaging optical system 25, and the imaging plane at the rear focal position coincides with the exposure surface of the substrate W. Hereafter, the imaging plane of the first imaging optical system 25 will be referred to as the conjugate plane as needed.

[0027] As the substrate W moves along the main scanning direction X, the projection area (exposure area) of the DMD22 moves relative to the substrate W. The exposure operation is performed according to a predetermined exposure pitch so that pattern light is irradiated according to the position of the projection area. As a result, a pattern is formed along the main scanning direction.

[0028] The other exposure heads 202 operate similarly, performing exposure while raster scanning, and forming a pattern across the entire substrate. Once the drawing process is complete, development, etching or plating, resist stripping, etc., are performed to produce a substrate with the pattern formed on it.

[0029] Here, the movement direction of the substrate W is aligned with the main scanning direction, but the substrate W may also be placed on the drawing table 18 with a slight inclination relative to the main scanning direction X. In this case, when the drawing table 18 moves along the main scanning direction X, the exposure area moves relative to the substrate W with an inclination relative to the longitudinal direction (X direction). As for the exposure method, a step-and-repeat method or a continuous movement method with multiple exposure can be applied.

[0030] Next, the image-splitting optical system will be explained using Figures 3 and 4. Figure 3 shows the configuration of the image-splitting optical system 30. Figure 4 shows the configuration of the mirror pair of the reflective optical system.

[0031] The image splitting optical system 30 comprises a prism 32, a reflective optical system 34, and an optical path length adjustment optical member 36. Figure 2 shows a view of the prism 32 from above (towards the first imaging optical system 25), and is composed of four rectangular optical members 32A, 32B, 32C, and 32D, which are roughly trapezoidal when viewed from the side. Furthermore, the optical members 32A, 32B and optical members 32C, 32D are symmetrical with respect to the central line C.

[0032] As shown in Patent Document 1, the optical elements 32A, 32B, 32C, and 32D each have reflective surfaces that are in a parallel plane relationship. Furthermore, on the imaging surface of the first imaging optical system 25, which is the plane of the prism 32 composed of the surfaces of the optical elements 32A, 32B, 32C, and 32D (see Figure 2), the pattern image formed on the imaging surface of the first imaging optical system 26 is divided, just as in Patent Document 1. Here, the pattern image is divided into four parts, and the light from the four divided pattern images is guided to the reflective optical system 34.

[0033] The reflective optical system 34 comprises mirrors 34A, 34B, 34C, 34D, 34E, 34F, 34G, and 34H, each configured in pairs. Each pair of mirrors is parallel to the others, and the light from the four segmented pattern images is guided to the optical path length adjustment optical member 36.

[0034] Figure 4 shows mirror pairs 34A and 34B. Mirror pairs 34A and 34B are composed of galvanometer mirrors, such as those disclosed in Japanese Patent Publication No. 5-100434, and are rotatable on an axis. By rotating the mirror pairs 34A and 34B on an axis while maintaining their reflective surfaces in a parallel plane relationship, the optical path of the segmented pattern image can be changed without changing the optical axis direction toward the exposure surface. In other words, the projection position of the segmented pattern image can be changed. Other mirror pairs 34C and 34D, mirror pairs 34E and 34F, and mirrors 34G and 34H are configured similarly.

[0035] Figure 5 shows the reflective surface of the DMD22. According to the image division optical system 30, the reflective surface of the DMD22 is defined as four sub-regions DM1, DM2, DM3, and DM4, which are divided into four equal parts in the transverse direction (corresponding to the main scanning direction). The pattern image from the entire DMD22 is projected by the image division optical system 30 to different positions for each sub-region DM1, DM2, DM3, and DM4.

[0036] Figure 6 shows the projection positions of the segmented pattern images. When mirror pairs 34A, 34B, 34C, 34D, 34E, 34F, 34G, and 34H are positioned without axial rotation, the four segmented pattern images DA1 to DA4 are projected at the positions indicated by the dashed lines in Figure 6.

[0037] The divided pattern images DA1 to DA4 are pattern images corresponding to the sub-regions DM1, DM2, DM3, and DM4, respectively. Here, the projection point of the center of the exposure area when the pattern image is not divided (when there is no dividing optical system), i.e., the center position of DMD22, is defined as the origin of the XY coordinate system when the main scanning direction is X and the sub-scanning direction is Y, and this is explained accordingly.

[0038] In this embodiment, by adjusting the positions (tilt angles) of each mirror pair 34A, 34B, mirror pair 34C, 34D, mirror pair 34E, 34F, and mirrors 34G and 34H of the reflective optical system 34, four segmented pattern images DA1 to DA4 are projected at the positions shown by the solid lines. The four segmented pattern images DA1 to DA4 are positioned at equal intervals from each other with respect to the main scanning direction, and their projection positions are symmetrical with respect to the origin. Furthermore, the four segmented pattern images DA1 to DA4 are projected in accordance with the positions of the scanning bands SB1, SB2, SB3, and SB4, which are connected along the sub-scanning direction Y. The arrangement angles of each mirror pair 34A, 34B, mirror pair 34C, 34D, mirror pair 34E, 34F, and mirrors 34G and 34H are determined so that the segmented pattern images can move diagonally as shown in Figure 6, with respect to the exposure surface where the XY coordinate system is defined, and the direction perpendicular to the exposure surface (Z axis).

[0039] By configuring the reflective optical system 34 in this way, it becomes easy to perform raster data generation processing and exposure data generation processing as shown in Patent Document 2 above.

[0040] Furthermore, instead of using galvanometer mirrors for the reflective optical system 34, it is possible to replace it with a configuration in which one of the mirrors in each pair of mirrors is moved in a direction perpendicular to its reflective surface (normal direction) while maintaining a parallel plane relationship. A known mechanism can be used for the means of moving the mirrors; for example, the mirror moving mechanism disclosed in Japanese Patent Publication No. 1-049015 can be used.

[0041] Furthermore, it is possible to combine and provide a new pair of mirrors with each pair of mirrors. This makes it possible to freely adjust the positions of the divided pattern images DA1 to DA4 with respect to the XY coordinate system. Alternatively, the positions of the divided pattern images DA1 to DA4 may be adjusted by providing angle-adjustable optical members as disclosed in Japanese Patent Publication No. 2001-215718, Japanese Patent Publication No. 2001-042223, Japanese Patent Publication No. 2012-524988, etc. Alternatively, as shown in Japanese Patent Publication No. 2009-244446, the image position may be adjusted by adjusting the distance between the wedge prisms.

[0042] With respect to the optical path length modulating optical member 36, the focal position can be adjusted using an optical member described in the above-mentioned Patent Document 1, or a wedge-shaped prism as described in Japanese Patent No. 4244156.

[0043] Figure 7 is a block diagram of the exposure apparatus.

[0044] The drawing control unit 50 is connected to an external workstation (not shown) and includes an exposure control unit 52 to which a monitor 50B and a keyboard 50C are connected. The exposure control unit 52 controls the exposure operation process and outputs control signals to circuits such as the exposure data generation unit 76, timing control circuit 73, drawing table control circuit 53, and light source control unit 61. The program that controls the exposure operation process is stored in a ROM (not shown) within the exposure control unit 52.

[0045] The pattern data input to the exposure control unit 52 from the workstation (not shown) is vector data (CAD / CAM data) containing positional information (contour positional information) of the drawing pattern, and is represented as positional coordinate data based on the XY coordinate system.

[0046] The first, second, third, and fourth raster data generation units 72A, 72B, 72C, and 72D convert vector data and sequentially generate raster data for patterns to be drawn on scan bands SB1, SB2, SB3, and SB4, respectively. The generated raster data is temporarily stored in the first, second, third, and fourth buffer memories 74A, 74B, 74C, and 74D, respectively.

[0047] The raster data temporarily stored in each buffer memory is output according to the exposure pitch. That is, when the partial projection area moves by the exposure pitch and the next exposure operation becomes possible, the raster data is output. The output control of raster data in the first, second, third, and fourth raster data generation units 72A, 72B, 72C, and 72D is performed based on a control signal output from an address control circuit (not shown) provided in the exposure control unit 52.

[0048] When the raster data is sent to the exposure data generation unit 76, the raster data is integrated in the exposure data generation unit 76, and a signal to control the ON / OFF state of each micromirror of the DMD22 is generated as a single exposure data for the entire DMD22. In the DMD22, the micromirrors are controlled ON / OFF based on the exposure data output from the exposure data generation unit 76.

[0049] The timing control circuit 73 outputs a clock pulse signal as a synchronization signal to the buffer memories 74A, 74B, 74C, 74D, the exposure data generation unit 76, etc., for timing adjustment. In addition, based on the image signal output from the CCD sensor 19, the image processing unit 62 detects the position of the alignment marks formed on the substrate W.

[0050] The drawing table control circuit 53 controls an XY stage drive mechanism 56 equipped with a motor (not shown) via a drive circuit 54, thereby controlling the movement speed of the drawing table 18, the substrate feeding direction, etc. The position detection sensor 55 detects the relative position to the drawing table 18. Similarly, the exposure head 202 is also provided with circuits (not shown) related to raster data conversion processing, DMD drive processing, etc., and performs similar exposure operation processing.

[0051] The buffer memory structure, raster data generation process, and exposure data generation process are the same as those described in Patent Documents 1 and 2. This enables the formation of high-resolution segmented pattern images while performing data processing with excellent throughput.

[0052] Regarding image segmentation, the pattern image may be divided into five or more parts. The segmented pattern images can be arranged along the sub-scanning direction so that they overlap each other along the sub-scanning direction, or their projection positions can be moved so that they are spaced apart along the sub-scanning direction.

[0053] Regarding the buffer memory, it is also possible to adjust the output timing of multiple raster data by using a FIFO-type buffer memory that makes the input timing and output timing asynchronous. Furthermore, as shown in Japanese Patent Application Publication No. 2012-15718, the position of the divided pattern image may be observed, detected, and adjusted by providing an imaging unit such as a camera. [Explanation of symbols]

[0054] 10. Exposure apparatus 22 DMD (Optical Modulation Array) 24 Projection optical system 25. First imaging optical system 26. Second imaging optical system 30-image segmentation optical system 32 Prisms 34 Reflective optical system 36 Optical path length modulating optical components

Claims

1. An optical modulation element array in which multiple optical modulation elements are arranged in a two-dimensional array, The system includes a projection optical system that projects the light reflected by the aforementioned optical modulation element array onto the exposure surface of the object to be drawn, The aforementioned projection optical system, A first optical system that focuses the light of the pattern image reflected by the aforementioned optical modulation element array onto a first imaging plane, An image splitting optical system that splits a pattern image formed on the first imaging plane to form a plurality of split pattern images, The system includes a second optical system that images the light from the plurality of segmented pattern images onto the exposure surface, The aforementioned divided optical system A plurality of pairs of dividing mirrors for dividing the pattern image formed on the first imaging surface such that the plurality of divided pattern images are projected on the exposure surface at positions separated from each other by a predetermined distance with respect to the main scanning direction and the sub-scanning direction, wherein the plurality of pairs of dividing mirrors are inclined and intersect with respect to the first imaging surface and are in a parallel planar relationship, A reflective optical system that moves the light of the plurality of divided pattern images on the exposure surface, The system includes an optical path length modulation optical member that adjusts the optical path length of the light of the divided pattern image, The aforementioned reflective optical system comprises a plurality of pairs of mirrors that are in a parallel planar relationship with each other, An exposure head for an exposure apparatus, characterized in that at least one mirror of each pair of mirrors rotates on an axis or moves in translation according to the projection positions of a predetermined number of segmented pattern images.

2. The exposure head for an exposure apparatus according to claim 1, characterized in that each of the plurality of mirror pairs is composed of a pair of galvanometer mirrors that rotate on an axis while maintaining a parallel plane relationship.

3. The exposure head for an exposure apparatus according to claim 1, characterized in that one of the mirrors in each pair of mirrors moves in parallel along a direction perpendicular to its reflective surface.

4. The exposure head for an exposure apparatus according to claim 1, characterized in that one of the mirrors in each pair of mirrors rotates on an axis.

5. The exposure head for an exposure apparatus according to claim 1, further comprising an imaging unit for capturing the projection position of a segmented pattern image formed by the image segmentation optical system.

6. The exposure head for an exposure apparatus according to claim 1, characterized in that the optical path length modulating optical member has a wedge-shaped prism.

7. An exposure apparatus characterized by comprising an exposure head for an exposure apparatus according to any one of claims 1 to 6.

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