Exposure head for exposure device, and exposure device

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 writes a pattern using a light modulation element array such as a DMD (Digital Micro-mirror Device), and in particular to an optical system that projects a pattern image onto an exposure surface. [Background technology]

[0002] In a maskless exposure device equipped with a DMD, it is possible to split the pattern light reflected by the DMD and project multiple split pattern images along the sub-scanning direction. For example, an exposure device equipped with a splitting optical system that has a pair of reflecting optical systems is known (see Patent Document 1). In this device, a pair of mirrors in a parallel plane relationship is arranged in the same number as the number of splits, and the mirrors are arranged so as not to intersect with the imaging plane (conjugate plane) that is the image splitting plane, to form split pattern images.

[0003] In an exposure apparatus equipped with such a split optical system, the split pattern images are projected onto the exposure surface at intervals along the main scanning direction. Therefore, in order to effectively execute the raster data generation process for each scanning band (scanning area) and the exposure data generation process for the light modulation element array, the projection position of a specific split pattern image is used as a reference, and from the series of raster data generated sequentially according to each scanning band, raster data corresponding to a series of split pattern images is extracted and integrated to generate exposure data (see Patent Document 2).

[0004] On the other hand, a split optical system that forms a large number of split pattern images is known in which mirror pairs in a parallel plane relationship are prepared for the number of divisions, and the mirrors are arranged so as to intersect with the image formation plane (conjugate plane) (see Patent Document 3). In this system, the split mirrors are arranged to be inclined with respect to the conjugate plane and to intersect with each other at a predetermined interval in the main scanning direction and the sub-scanning direction.

[0005] Furthermore, maskless exposure apparatuses are also known that include a splitting optical system (see Patent Document 4) that has multiple triangular prism-shaped optical elements, each with a different inclination angle relative to the optical axis of the projection optical system, or a splitting optical system (see Patent Document 5) that splits the light reflected by the DMD into two parts 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] JP 2014-92707 A [Patent Document 5] JP 2009-87995 A Summary of the Invention [Problem to be solved by the invention]

[0007] When it is necessary to form a large number of divided pattern images (for example, a four-divided pattern image) and to project clear divided pattern images without insufficient light onto an exposure surface, it is possible to configure a division optical system that combines the above-mentioned Patent Documents 1 and 3. Even in such a case, it is required to configure an image division optical system that makes it possible to execute the raster data generation process and exposure data generation process as shown in the above-mentioned Patent Document 2 and facilitates improvement of throughput. [Means for solving the problem]

[0008] The exposure head for an exposure apparatus of the present invention comprises a light modulation element array in which a plurality of light modulation elements are arranged two-dimensionally, and a projection optical system that images the light reflected by the light modulation element array on an exposure surface of an object to be drawn, the projection optical system comprising a first optical system that images the light of a pattern image reflected by the light modulation element array on a first image surface, an image division optical system that divides the pattern image formed on the first image surface according to boundary lines defined in the sub-scanning direction on the first image surface to form a plurality of divided pattern images, a reflection optical system that moves the light of the plurality of divided pattern images on the exposure surface, and a second optical system that images the light of the plurality of divided pattern images moved by the reflection optical system on the exposure surface. The reflection optical system comprises a plurality of mirror pairs that are in a mutually parallel plane relationship, and at least one mirror of each mirror pair moves in accordance with the projection positions of the plurality of determined divided pattern images. and rotate or translate around an axis.

[0009] There are various configurations of the mirror pairs. As a configuration of the mirror pairs that can rotate about an axis, for example, multiple mirror pairs can be configured by a pair of galvanometer mirrors that rotate about an axis while maintaining a parallel plane relationship. Also, as a configuration of a mirror pair that moves in parallel, it is possible to configure one mirror of each mirror pair to move in parallel (relatively) along a direction perpendicular to its reflecting surface. In either configuration, it is possible to move the divided pattern image in a predetermined direction, for example, in a direction inclined with respect to the main scanning direction and the sub-scanning direction. Alternatively, it is also possible to configure one mirror of each mirror pair to rotate about an axis.

[0010] According to such an image division optical system, a pattern image formed by light reflected by the light modulation element array can be divided to form a plurality of divided pattern images arranged at a predetermined interval along the main scanning direction and at different positions along the sub-scanning direction. For example, in an exposure device including an exposure operation processing unit that converts pattern data, which is vector data, into raster data and controls each light modulation element according to the raster data, the exposure operation processing unit can include a raster data generating unit that generates a plurality of raster data for a plurality of scanning bands according to a common reference position, the position of one partial projection area in the main scanning direction among a plurality of partial projection areas formed by a plurality of divided pattern images and moving relatively along a plurality of scanning bands, and an exposure data generating unit that extracts and integrates raster data corresponding to the positions of the plurality of partial projection areas from a series of a plurality of raster data sequentially generated during scanning, and generates exposure data for the entire light modulation element array.

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

[0012] The optical system may further include an imaging unit that images a projection position of the divided pattern image formed by the image splitting optical system. Also, the optical system may further include an optical path length modulation optical member that adjusts the optical path length of the light of the divided pattern image formed by the image splitting optical system. Effect of the Invention

[0013] According to the present invention, it is possible to configure an image splitting optical system that facilitates improvement of throughput. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view that shows a schematic diagram of an exposure apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating an internal configuration of an exposure head. [Diagram 3] FIG. 2 is a diagram showing a configuration of an image splitting optical system 30. [Figure 4] FIG. 2 is a diagram showing a configuration of a mirror pair of a reflective optical system. [Diagram 5] FIG. 2 is a diagram showing a reflecting surface of the DMD 22. [Figure 6] FIG. 13 is a diagram showing projection positions of divided pattern images. [Figure 7] FIG. 2 is a block diagram of an exposure apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0016] FIG. 1 is a perspective view that shows a schematic diagram of an exposure apparatus according to the present embodiment.

[0017] The exposure apparatus 10 is a maskless exposure apparatus that directly irradiates a pattern light onto a substrate W coated (or attached) with a photosensitive material such as photoresist, and includes a gate-shaped structure 12 and a base 14. An XY stage driving 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 forming a pattern 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 a similar configuration, and projects a pattern image using the light from the light source 20b.

[0019] The rectangular substrate W is, for example, a substrate for electronic circuits such as a printed circuit board, dry film, or glass substrate, and is mounted on the drawing table 18 in a blank state after undergoing pre-baking, coating / attachment of photosensitive material, etc. A mutually orthogonal XYZ coordinate system is defined for the substrate W (drawing table 18), and the drawing table 18 is movable along the X and Y directions and can also rotate 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, a keyboard, and the like (not shown here) are connected to the drawing control unit, and settings related to the drawing process are made according to the operation of an operator. A CCD 19 provided on the protruding portion 31 detects the deformation state of the substrate W, and the exposure operation is performed after the alignment is adjusted.

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

[0022] 1 is guided via an illumination optical system (not shown) to the DMD 22. The DMD 22 is an optical modulation device in which minute rectangular micromirrors of several μm to several tens of μm are two-dimensionally arranged in a matrix, and is composed of, for example, 1024 × 768 micromirrors.

[0023] In the DMD 22, each micromirror is selectively controlled to be turned ON / OFF based on a control signal (exposure data) stored in a memory cell. The light reflected by the micromirror in the ON state is a light 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 includes 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 an imaging surface CS (first imaging surface) located at a focal position, and enlarges the entire pattern image by a predetermined magnification.

[0025] The image splitting optical system 30 splits the pattern image formed on the imaging plane of the first imaging optical system 25 into multiple parts. Here, a pattern image split into four parts (hereinafter, referred to as split pattern images) is formed. The light of the split pattern images formed by the image splitting optical system 30 is imaged on the exposure plane 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 back focal position coincides with the exposure surface of the substrate W. Hereinafter, the imaging plane of the first imaging optical system 25 will be referred to as a conjugate plane as necessary.

[0027] As the substrate W moves along the main scanning direction X, the projection area (exposure area) of the DMD 22 moves relative to the substrate W. An exposure operation is performed according to a determined exposure pitch so as to irradiate a pattern light 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 are similarly configured, performing exposure operations while performing raster scanning, and forming a pattern over the entire substrate. After the drawing process is completed, development, etching or plating, resist stripping, and other processes are performed to produce a substrate on which a pattern has been formed.

[0029] Here, the movement direction of the substrate W is aligned with the main scanning direction, but the substrate W may be placed on the drawing table 18 in a state where it is slightly tilted with respect 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 relatively while being tilted with respect to the longitudinal direction (X direction) of the substrate W. As an exposure method, a multiple exposure method using a step & repeat method or a continuous movement method can be applied.

[0030] Next, the image splitting optical system will be described with reference to Figures 3 and 4. Figure 3 is a diagram showing the configuration of the image splitting optical system 30. Figure 4 is a diagram showing the configuration of a mirror pair of the reflective optical system.

[0031] The image splitting optical system 30 includes a prism 32, a reflecting optical system 34, and an optical path length adjusting optical member 36. Fig. 2 shows the prism 32 as viewed from above (the first imaging optical system 25 side), and is composed of four rectangular optical members 32A, 32B, 32C, and 32D, and has a substantially trapezoidal shape as viewed from the side. The optical members 32A and 32B and the optical members 32C and 32D are symmetrical with respect to the center line C.

[0032] As shown in the above Patent Document 1, the optical members 32A, 32B, 32C, and 32D each have a reflecting surface that is in a parallel plane relationship. Also, on the plane of the prism 32 (see FIG. 2), which is the imaging plane of the first imaging optical system 25 and is configured by the surfaces of the optical members 32A, 32B, 32C, and 32D, the pattern image formed on the imaging plane of the first imaging optical system 26 is divided, as in the above Patent Document 1. Here, the pattern image is divided into four, and the light of the four divided pattern images is guided to the reflection optical system 34.

[0033] The reflection optical system 34 includes pairs of mirrors 34A and 34B, mirrors 34C and 34D, mirrors 34E and 34F, and mirrors 34G and 34H. Each pair of mirrors is parallel to each other, and the light of the four divided pattern images is guided to an optical path length adjustment optical member 36.

[0034] FIG. 4 shows mirror pairs 34A and 34B. The mirror pairs 34A and 34B are formed of galvanometer mirrors, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-100434, and each of them can rotate about its axis. The mirror pairs 34A and 34B rotate about their axes while maintaining their reflecting surfaces in a parallel plane relationship, and can change the optical path of the light of the divided pattern image without changing the direction of the optical axis toward the exposure surface. In other words, the projection position of the divided pattern image can be changed. The other mirror pairs 34C and 34D, mirror pairs 34E and 34F, and mirrors 34G and 34H are also formed in the same manner.

[0035] 5 is a diagram showing the reflecting surface of the DMD 22. According to the image splitting optical system 30, the reflecting surface of the DMD 22 is divided into four equal partial regions DM1, DM2, DM3, and DM4 in the horizontal direction (according to the main scanning direction). The pattern image of the entire DMD 22 is projected by the image splitting optical system 30 onto different positions for each of the partial regions DM1, DM2, DM3, and DM4.

[0036] Fig. 6 is a diagram showing the projection positions of the divided pattern images. When the mirror pairs 34A and 34B, the mirror pairs 34C and 34D, the mirror pairs 34E and 34F, and the mirrors 34G and 34H are positioned so as not to rotate about their axes, the four divided pattern images DA1 to DA4 are projected at the positions shown by the dashed lines in Fig. 6.

[0037] The divided pattern images DA1 to DA4 are pattern images corresponding to the partial regions DM1, DM2, DM3, and DM4, respectively. In this description, the center point of the exposure area when the pattern image is not divided (when the dividing optical system is not provided), that is, the projection point of the center position of the 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.

[0038] In this embodiment, the four divided pattern images DA1 to DA4 are projected at positions indicated by solid lines by adjusting the positions (tilt angles) of the mirror pairs 34A, 34B, mirror pairs 34C, 34D, mirror pairs 34E, 34F, and mirrors 34G, 34H of the reflection optical system 34. The four divided pattern images DA1 to DA4 are positioned at equal intervals in the main scanning direction, and the projection positions are symmetrical with respect to the origin. The four divided pattern images DA1 to DA4 are projected in accordance with the positions of the scanning bands SB1, SB2, SB3, SB4 aligned along the sub-scanning direction Y. The arrangement angles of the mirror pairs 34A, 34B, mirror pairs 34C, 34D, mirror pairs 34E, 34F, and mirrors 34G, 34H are determined such that the divided pattern images can be moved in an oblique direction as shown in FIG. 6 with respect to the exposure surface on which the XY coordinate system is defined and the vertical direction (Z axis) to the exposure surface.

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

[0040] In addition, instead of configuring the reflection optical system 34 with a galvanometer mirror, it is possible to use a configuration in which one mirror of each mirror pair is moved in a direction perpendicular to the reflection surface (normal direction) while maintaining a parallel plane relationship. A known mechanism can be used as a means for moving the mirror, and for example, the mirror movement mechanism disclosed in Japanese Patent Application Laid-Open No. 1-049015 can be used.

[0041] Furthermore, it is also possible to provide a new mirror pair in combination with each mirror pair. This allows the positions of the divided pattern images DA1 to DA4 to be freely adjusted with respect to the XY coordinate system. Alternatively, the positions of the divided pattern images DA1 to DA4 may be adjusted by providing an angle-adjustable optical member as disclosed in JP 2001-215718 A, JP 2001-042223 A, JP 2012-524988 A, etc. Alternatively, the image positions may be adjusted by adjusting the distance between wedge prisms as shown in JP 2009-244446 A.

[0042] Regarding the optical path length modulation optical member 36, the optical member described in the above Patent Document 1 or a wedge prism as described in Japanese Patent No. 4244156 may be used to adjust the focal position.

[0043] FIG. 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 an exposure data generation unit 76, a timing control circuit 73, a drawing table control circuit 53, and a light source control unit 61. A program for controlling the exposure operation process is stored in a ROM (not shown) in the exposure control unit 52.

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

[0046] The first, second, third and fourth raster data generating units 72A, 72B, 72C and 72D convert the vector data and sequentially generate raster data of the patterns to be drawn on the scan bands SB1, SB2, SB3 and SB4, respectively. The generated raster data are 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 in accordance with the exposure pitch. That is, when the partial projection area moves by the exposure pitch and the next exposure operation can be performed, the raster data is output. The output control of the raster data in the first, second, third and fourth raster data generating 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 exposure data generation unit 76 integrates the raster data and generates a signal that controls the ON / OFF of each micromirror of the DMD 22 as one exposure data for the entire DMD 22. In the DMD 22, the micromirrors are controlled to be turned 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 for adjusting timing to the buffer memories 74A, 74B, 74C, 74D, the exposure data generation unit 76, etc. Also, based on the image signal output from the CCD sensor 19, the image processing unit 62 detects the position of an alignment mark 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 moving speed of the drawing table 18, the substrate feed direction, etc. A position detection sensor 55 detects the relative position with respect to the drawing table 18. Similarly, circuits (not shown) related to raster data conversion processing, DMD drive processing, etc. are provided for the exposure head 202, and similar exposure operation processing is performed.

[0051] The buffer memory structure, raster data generation processing, and exposure data generation processing are performed in the same manner as in the above-mentioned Patent Documents 1 and 2. This makes it possible to form a high-resolution divided pattern image while performing data processing with excellent throughput.

[0052] Regarding image division, the pattern image may be divided into five or more parts. The divided pattern images may be arranged along the sub-scanning direction so as to overlap each other along the sub-scanning direction, or the projection positions may be moved so as to provide intervals between each other along the sub-scanning direction.

[0053] Regarding the buffer memory, it is possible to adjust the output timing of each of the multiple raster data by using a FIFO type buffer memory that makes the input timing and the output timing asynchronous instead. Also, as shown in JP2012-15718A, an imaging unit such as a camera may be provided to observe, detect, and adjust the position of the divided pattern image. [Explanation of symbols]

[0054] 10 Exposure equipment 22 DMD (Digital Modulator Array) 24 Projection optical system 25 First imaging optical system 26 Second imaging optical system 30 Image division optical system 32 Prism 34 Reflective optical system 36 Optical path length modulation optical components

Claims

1. a light modulation element array in which a plurality of light modulation elements are arranged two-dimensionally; a projection optical system that forms an image of the light reflected by the light modulation element array on an exposure surface of an object to be drawn, The projection optical system comprises: a first optical system that forms an image of the pattern image reflected by the light modulation element array on a first image forming plane; an image splitting optical system that splits a pattern image formed on the first image forming plane to form a plurality of split pattern images; a second optical system that focuses the light of the plurality of divided pattern images onto the exposure surface, The splitting optical system is a plurality of split mirror pairs that split a pattern image formed on the first image forming plane so that the plurality of split pattern images are projected on the exposure plane at positions spaced apart from each other by a predetermined distance in the main scanning direction and the sub-scanning direction, the plurality of split mirror pairs being inclined and intersecting with the first image forming plane and each being in a parallel plane relationship; a reflection optical system that moves light of the plurality of divided pattern images on the exposure surface; an optical path length modulation optical member for adjusting an optical path length of the light of the divided pattern image; The reflection optical system includes a plurality of mirror pairs that are in a plane-parallel relationship with each other, An exposure head for an exposure apparatus, wherein at least one mirror of each mirror pair rotates axially or moves parallel to the substrate in accordance with the projection positions of a plurality of determined divided pattern images.

2. 2. An exposure head for an exposure apparatus according to claim 1, wherein each of said plurality of mirror pairs is constituted by a pair of galvanometer mirrors which rotate on an axis while maintaining a parallel plane relationship.

3. 2. An exposure head for an exposure apparatus according to claim 1, wherein one mirror of each mirror pair translates in a direction perpendicular to its reflecting surface.

4. 2. An exposure head for an exposure apparatus according to claim 1, wherein one mirror of each mirror pair rotates about an axis.

5. 2. The exposure head for an exposure apparatus according to claim 1, further comprising an image pickup unit that picks up an image of a projection position of a divided pattern image formed by the image division optical system.

6. An exposure head for an exposure apparatus as described in claim 1, characterized in that the optical path length modulating optical element has a wedge-shaped prism.

7. 7. An exposure apparatus comprising an exposure head for an exposure apparatus according to claim 1.

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