Alignment device and exposure device

Abstract

The present invention provides technology capable of achieving highly precise positioning even when the position of a mark inside a substrate has shifted. A control unit (70) images, with an X-ray camera (60), a mark (90) of a substrate (9) held by a holding stage (25), and acquires the approximate position of the mark (90). The control unit (70) moves the holding stage (25) on the basis of the approximate position to bring the mark (90) of the substrate (9) closer to the optical axis (XL1) of an X-ray source (61). In this state, the mark (90) is imaged with the X-ray camera (60), and the position of the mark (90) is acquired.

Description

Alignment apparatus and exposure apparatus

[0001] The subject matter disclosed herein relates to alignment apparatus and exposure apparatus.

[0002] Conventionally, in exposure apparatuses for exposing substrates, a technique disclosed in Patent Document 1 is known as a positioning technique for exposure based on marks or structures provided inside the substrate. This technique uses an X-ray projection system to photograph marks inside the substrate and identify the position of the substrate, thereby enabling high-precision exposure.

[0003] Japanese Patent Application Publication No. 11-330710

[0004] Incidentally, since X-rays are emitted from the X-ray source while spreading at a predetermined angle, in order to accurately obtain the position of a mark, it is necessary to bring the mark as close as possible to the optical axis of the X-rays. For example, in actual manufacturing sites, when photographing marks on a substrate, positional errors of the marks relative to the reference edge of the substrate may occur. Since marks are not always placed on the substrate according to the design drawings, if photography is performed based on the design drawings, it may result in a situation where the X-rays are not irradiated perpendicularly to the marks. If a positional shift occurs in the XY direction between the mark and the X-ray source, the geometric magnification during photography will fluctuate due to the positional variation of the mark in the Z-axis direction within the substrate. As a result, it becomes difficult to obtain the accurate position of the mark, and there was a problem in that high-precision positioning could not be achieved.

[0005] The objective of the present invention is to provide a technology that enables high-precision positioning even when misalignment occurs of marks inside the substrate.

[0006] To solve the above problems, the first embodiment provides an alignment apparatus comprising: a stage for holding a substrate on which marks are formed; an X-ray camera having an X-ray source positioned on one side of the stage for irradiating with X-rays and an X-ray detector positioned on the other side of the stage for detecting the X-rays; a stage moving unit for moving the stage; and a control unit for controlling the X-ray source and the stage moving unit. The control unit performs an approximate position acquisition process in which it photographs the marks on the substrate held on the stage with the X-ray camera and acquires the approximate position of the marks; and a position acquisition process in which, based on the approximate position, the stage is moved so that the marks on the substrate approach the optical axis of the X-ray source, and the marks are photographed with the X-ray camera to acquire the position of one or more marks. This reduces geometrical scaling fluctuations caused by positional fluctuations of the marks in the Z-axis direction within the substrate, allowing for accurate acquisition of the mark positions. Therefore, alignment accuracy can be improved.

[0007] The second embodiment is an alignment apparatus according to the first embodiment, wherein the exposure time of the X-ray camera in the approximate position acquisition process is shorter than the exposure time of the X-ray camera in the position acquisition process.

[0008] A third embodiment is an alignment device according to the first or second embodiment, wherein the number of marks whose approximate position is acquired in the approximate position acquisition process is less than the number of marks whose position is acquired in the position acquisition process.

[0009] A fourth embodiment is an alignment apparatus according to the first or second embodiment, wherein the approximate position acquisition process includes a process for acquiring the approximate positions of two or more marks, and the position acquisition process includes a process for moving the stage based on the approximate positions of the two or more marks.

[0010] A fifth embodiment is an alignment apparatus according to the first or second embodiment, wherein the stage moving unit is capable of moving the stage in a first direction and in a second direction intersecting the first direction, the substrate has a row of marks consisting of a plurality of marks arranged in the first direction, the approximate position acquisition process includes a process of acquiring the approximate positions of two or more marks in the row of marks, and the position acquisition process includes a process of moving the stage so that the two or more marks whose approximate positions have been acquired approach the optical axis of the X-ray source.

[0011] The sixth embodiment is an alignment apparatus according to the fifth embodiment, wherein the substrate has a first row of marks arranged in a line and a second row of marks arranged in the first direction and separated from the first row of marks in the second direction, and the control unit performs the approximate position acquisition process and the position acquisition process for the first row of marks, then moves the stage in the second direction, and performs the approximate position acquisition process and the position acquisition process for the second row of marks.

[0012] The seventh embodiment is an alignment apparatus according to the first or second embodiment, wherein the stage comprises a metal frame having an opening on its interior, and an X-ray transparent reinforcing member provided in the frame to close at least a portion of the opening.

[0013] The eighth aspect is an alignment device according to the seventh aspect, wherein the drive unit of the stage moving part is fixed to the frame.

[0014] The ninth aspect is an alignment device according to the seventh aspect, wherein the reinforcing member is a flat plate member fixed to the outer surface of the frame and closing the opening.

[0015] The tenth embodiment is an exposure apparatus comprising an alignment apparatus according to the first or second embodiment and an exposure unit for exposing the substrate.

[0016] According to the first to tenth embodiments, the stage is moved based on the approximate position of the mark obtained in a pre-imaging, and imaging is performed with the mark closer to the X-ray optical axis. This reduces the geometric magnification fluctuation caused by the positional fluctuation of the mark in the Z-axis direction within the substrate, thereby enabling accurate acquisition of the mark's position. Consequently, alignment accuracy can be improved.

[0017] According to the alignment device of the second embodiment, the position of the mark can be acquired efficiently by shortening the exposure time.

[0018] According to the alignment device of the third embodiment, the position of the mark can be acquired efficiently and with high precision.

[0019] According to the alignment apparatus of the fourth embodiment, by acquiring the approximate positions of two or more marks, the misalignment of the entire substrate can be detected, allowing for appropriate stage movement. This enables the marks to be brought closer to the X-ray optical axis with high precision, and the position of the marks can be acquired with high accuracy.

[0020] According to the alignment device of the fifth embodiment, the position of each mark in a row of marks arranged in the first direction can be acquired with high precision.

[0021] According to the alignment apparatus of the seventh embodiment, by performing X-ray imaging through the opening, interference with X-ray imaging can be suppressed. Furthermore, by providing a reinforcing member in the opening, the rigidity of the stage is improved, and deformation during movement can be suppressed.

[0022] According to the alignment device of the eighth embodiment, when the drive unit moves together with the frame, the deformation of the frame due to the weight of the drive unit can be effectively suppressed by the reinforcing member.

[0023] According to the alignment device of the ninth embodiment, by fixing a flat reinforcing member to the outer surface, the out-of-plane bending rigidity is improved, and deformation during movement can be effectively suppressed.

[0024] This is a perspective view showing the overall configuration of the exposure apparatus according to the embodiment. This is a schematic side view showing the main part of the exposure apparatus for X-ray imaging of marks provided on a substrate. This is a schematic top view of the X-stage. This is a schematic exploded view of the X-stage. This is a control block diagram of the exposure apparatus. This is a diagram showing a flowchart of the alignment process. This is a top view showing a substrate 9 on which multiple marks are provided. This is a diagram conceptually showing the pre-imaging process for the first row of marks. This is a diagram conceptually showing the mark imaging process for the first row of marks. This is a diagram conceptually showing the pre-imaging process for the second row of marks. This is a diagram conceptually showing the mark imaging process for the second row of marks.

[0025] Embodiments of the present invention will be described below with reference to the attached drawings. Note that in the drawings, dimensions and numbers of parts may be exaggerated or simplified for ease of understanding. Figure 1 and subsequent figures define an XYZ Cartesian coordinate system to explain positional relationships. Here, the X-axis and Y-axis directions are defined as horizontal. The Y-axis direction and X-axis direction are orthogonal to each other. Furthermore, the vertical direction perpendicular to the X-axis and Y-axis directions is defined as the Z-axis direction. In the following description, the +Z direction is defined as vertically upward, and the -Z direction is defined as vertically downward.

[0026] <1. Embodiment> Figure 1 is a perspective view showing the overall configuration of an exposure apparatus 1 according to an embodiment. The exposure apparatus 1 is a device that irradiates light onto the upper surface of a substrate 9 coated with a photosensitive material to expose a pattern onto the upper surface of the substrate 9. The substrate 9 is, for example, a printed circuit board or a semiconductor substrate. For example, in the manufacturing process of a printed circuit board, the process of forming a layer on the upper surface of the substrate 9 in another device and the process of exposing a pattern onto the upper surface of the substrate 9 in this exposure apparatus 1 are repeatedly performed. As a result, a multilayer printed circuit board (hereinafter also simply referred to as a "multilayer substrate") is manufactured.

[0027] As shown in Figure 1, the exposure apparatus 1 comprises a base unit 10, two gantry units 15, a Y-stage 21, a Y-stage moving unit 21M, an X-stage 23, an X-stage moving unit 23M, a holding stage 25, a Zθ stage 27, an exposure unit 40, a visible light camera 50, an X-ray camera 60, and a control unit 70. The base unit 10, Y-stage 21, Y-stage moving unit 21M, X-stage 23, X-stage moving unit 23M, holding stage 25, Zθ stage 27, X-ray camera 60, and control unit 70 of the exposure apparatus 1 constitute an alignment apparatus.

[0028] The base portion 10 is a support base that supports components of the exposure apparatus 1, such as the gantry 15 and the Y-stage 21. The base portion 10 is made of a stone material such as granite. The base portion 10 is fixed to the floor surface of a factory, for example. The base portion 10 has a flat, plate-like outer shape that extends along the horizontal plane. In this case, the base portion 10 is rectangular in shape when viewed from above. In the horizontal direction, the direction along the short side of the base portion 10 is the X-axis direction, and the direction along the long side is the Y-axis direction.

[0029] The two gantry units 15 are fixed to the upper surface of the base unit 10. The two gantry units 15 are spaced apart in the Y-axis direction. Each gantry unit 15 has a pair of legs 151 and a bridging section 152. The pair of legs 151 are spaced apart in the X-axis direction. Each leg 151 extends upward (in the +Z direction) from the upper surface of the base unit 10. The bridging section 152 connects the upper ends of the legs 151 in the X-axis direction. A through-hole 18 is formed between the upper surface of the base unit 10 and each gantry unit 15, through which the substrate 9 can pass in the Y-axis direction.

[0030] The Y-stage 21 is mounted on the base portion 10 in a substantially horizontal position. The Y-stage 21 is a platform that can move along the Y-axis direction (first direction) relative to the base portion 10. The Y-stage 21 has a flat plate-like outer shape. When viewed from above, the outer shape of the Y-stage 21 is rectangular, smaller than the base portion 10.

[0031] The Y-stage moving unit 21M is a mechanism capable of controlling the movement of the Y-stage 21 in the Y-axis direction relative to the base unit 10. The Y-stage moving unit 21M is a linear motor mechanism having a pair of guide rails and a linear motor. The pair of guide rails are rails for guiding the Y-stage 21 in the Y-axis direction, which is the main scanning direction. The pair of guide rails are provided on the upper surface of the base unit 10 at intervals in the X-axis direction, which is the sub-scanning direction. The pair of guide rails extend linearly along the Y-axis direction. The linear motor has a stator provided on the upper surface of the base unit 10 and a movable element fixed to the lower surface of the Y-stage 21. When a drive signal is supplied to the linear motor from the control unit 70, the movable element moves along the stator in the Y-axis direction due to the magnetic attractive and repulsive forces generated between the stator and the movable element. As a result, the Y-stage 21 moves in the Y-axis direction relative to the base unit 10. Note that the drive source of the Y-stage moving unit 21M is not limited to a linear motor. The Y-stage moving section 21M may be, for example, a mechanism that converts the rotational motion of a servo motor into linear motion using a ball screw.

[0032] The X-stage 23 is mounted on the Y-stage 21 in a substantially horizontal position. The X-stage 23 is a stage that can move along the X-axis direction (second direction) relative to the Y-stage 21. The X-stage 23 has a flat plate-like outer shape. Its outer shape in a top view is rectangular, smaller than the outer shape of the Y-stage 21.

[0033] The X-stage moving unit 23M can control the movement of the X-stage 23 relative to the Y-stage 21 in the X-axis direction, which is the sub-scanning direction. The X-stage moving unit 23M is a linear motor mechanism having a pair of guide rails and a linear motor. The pair of guide rails are rails for guiding the X-stage 23 in the sub-scanning direction. The pair of guide rails are provided on the upper surface of the Y-stage 21 at intervals in the main scanning direction. Each guide rail extends linearly along the sub-scanning direction. However, the X-stage moving unit 23M is not limited to a linear motor mechanism and may be a ball screw mechanism.

[0034] The holding stage 25 is a member that holds the substrate 9. The holding stage 25 is disposed on the X stage 23 via the Zθ stage 27. The holding stage 25 has a plurality of suction holes in the upper part, and adsorbs and holds the substrate 9 by sucking air through the plurality of suction holes. Note that the holding stage 25 may have chuck pins for fixing the substrate 9. The holding stage 25 is formed of a material such as carbon that can transmit X-rays irradiated from the X-ray source 61 of the X-ray camera 60.

[0035] The Zθ stage 27 is fixed on the X stage 23. The Zθ stage 27 is configured to be able to control the movement of the holding stage 25 along the Z-axis direction with respect to the X stage 23 and to be able to control the rotation about the θ-axis extending along the Z-axis direction. The Zθ stage 27 is formed of a material such as carbon that can transmit X-rays irradiated from the X-ray source 61 of the X-ray camera 60.

[0036] The exposure apparatus 1 moves the substrate 9 held by the holding stage 25 in the Y-axis direction (main scanning direction) and the X-axis direction (sub-scanning direction) respectively by operating the Y stage moving unit 21M and the X stage moving unit 23M.

[0037] The exposure unit 40 is a unit that exposes the substrate 9 supported by the holding stage 25. The exposure unit 40 has a plurality of heads 41, an illumination optical system 42, and a laser oscillator 43. The plurality of heads 41, the illumination optical system 42, and the laser oscillator 43 are fixed to the cross-bridge portion 152 of the gantry 15 disposed on the +Y side among the two gantries 15. The plurality of heads 41 are disposed between the two gantries 15 in the Y-axis direction. The plurality of heads 41 are arranged at intervals along the X-axis direction.

[0038] The laser oscillator 43 emits light based on a drive signal supplied from the control unit 70. The light emitted from the laser oscillator 43 is introduced to each head 41 via the illumination optical system 42. A spatial modulator is provided inside each head 41. For the spatial modulator, for example, a diffraction grating type spatial light modulator such as GLV (Grating Light Valve) (registered trademark) can be used. The light introduced to each head 41 is modulated into a predetermined pattern by the spatial modulator and irradiated onto the upper surface of the substrate 9. This exposes the photosensitive material on the upper surface of the substrate 9. A DMD (Digital Micromirror Device) may be used instead of a GLV. Also, a mercury lamp or LED may be used as the light source instead of the laser oscillator 43.

[0039] When the exposure apparatus 1 is in operation, the Y-stage 21 moves the substrate 9 in the Y-axis direction while irradiating it with light from each head 41. As a result, a pattern is exposed on the upper surface of the substrate 9 in a stripe-like area consisting of multiple band-shaped regions extending in the Y-axis direction. In addition, the X-stage 23 moves the substrate 9 by a predetermined distance in the X-axis direction, causing the exposure position of each head 41 relative to the substrate 9 to shift in the X-axis direction. In this way, the movement of the substrate 9 in the Y-axis direction and the movement in the X-axis direction relative to each head 41 are repeated alternately, so that the pattern is exposed over the entire upper surface of the substrate 9.

[0040] The visible light camera 50 is located on the +Y side of the bridging portion 152 in the gantry 15, which is positioned on the +Y side of the two gantry 15s. The visible light camera 50 has an image sensor made of a CCD (Charge-Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) and an optical system for introducing light to the image sensor. The visible light camera 50 may also have a light source for illuminating the object to be photographed. The visible light camera 50 transmits the captured visible light image to the control unit 70. The visible light image is a two-dimensional image composed of a large number of pixels arranged in two directions corresponding to the X-axis and Y-axis directions, respectively.

[0041] The visible light camera 50 is configured to be movable along the X-axis direction by a visible light camera moving unit (not shown) provided at the cross-bridge portion 152 of the gantry 15. The position of the visible light camera 50 in the X-axis direction can be controlled by the control unit 70. As the driving method of the visible light camera moving unit, various methods such as a linear motor method, a ball screw method, or a belt driving method can be adopted.

[0042] The X-ray camera 60 is a camera that takes pictures using X-rays. The X-ray camera 60 includes an X-ray source 61 and two X-ray detectors 63. The X-ray source 61 is provided on the -Y side surface of the cross-bridge portion 152 of the gantry 15 on the -Y side among the two gantries 15. The X-ray source 61 irradiates an X-ray beam downward. The X-ray camera 60 is an example of an imaging unit.

[0043] The two X-ray detectors 63 are arranged below the X-ray source 61 and are fixed to the upper surface of the base portion 10 here. The two X-ray detectors 63 are arranged at intervals in the X-axis direction. The X-ray detector 63 has an X-ray image sensor that detects X-rays emitted from the X-ray source 61. The X-ray image sensor has a detection surface that extends in the X-axis direction and the Y-axis direction. The X-ray detector 63 generates an X-ray image based on the intensity of the X-rays detected at each position of the detection surface and transmits the obtained X-ray image to the control unit 70. The X-ray image is a two-dimensional image composed of a large number of pixels arranged in two directions corresponding to the X-axis direction and the Y-axis direction respectively.

[0044] The X-ray source 61 is configured to be movable in the X-axis direction by an X-ray source moving unit 65 provided at the cross-bridge portion 152 of the gantry 15. The position of the X-ray source 61 in the X-axis direction can be controlled by the control unit 70. That is, the X-ray source 61 can be controlled to move in the X-axis direction with respect to the base portion 10. As the method of the X-ray source moving unit 65, various methods such as a linear motor method, a ball screw method, or a belt driving method can be adopted.

[0045] Figure 2 is a schematic side view showing the main parts of an exposure apparatus 1 for X-ray imaging of a mark 90 provided on a substrate 9. The substrate 9 shown in Figure 2 is a multilayer substrate having multiple layers on a substrate body, and one or more marks 90 are formed inside. The mark 90 is a reference mark for alignment and is a mark that can be photographed by an X-ray camera 60. The mark 90 is, for example, a hole formed in the copper foil layer of the substrate 9. The shape of the mark 90 in a top view is, for example, circular. However, the mark 90 may be a shape other than circular, such as a rectangle or a cross.

[0046] As shown in Figure 2, the X-ray source 61 of the X-ray camera 60 is positioned on the +Z side of the holding stage 25. The X-ray detector 63 is positioned on the -Z side of the Y stage 21. Therefore, when imaging the mark 90 on the substrate 9 with the X-ray camera 60, the X-rays irradiated by the X-ray source 61 pass through the substrate 9, the holding stage 25, the Zθ stage 27, the X stage 23, and the Y stage 21 before entering the X-ray detector 63. In order to obtain a clear X-ray image, the Y stage 21, X stage 23, holding stage 25, and Zθ stage 27 are required to have high X-ray transmittance.

[0047] Figure 3 is a schematic top view of the X-stage 23. Figure 4 is a schematic exploded view of the X-stage 23. The X-stage 23 has a frame 231 and reinforcing members 233. In a top view, the frame 231 has two beam sections along the Y-axis and two beam sections along the X-axis. The frame 231 has a rectangular opening 231P that penetrates through the center in the Z-axis direction. The frame 231 is made of a metal such as aluminum or iron.

[0048] The reinforcing member 233 is a member provided to increase the rigidity of the frame 231. The reinforcing member 233 is fixed to the frame 231 and closes the opening 231P of the frame 231. The reinforcing member 233 is a rectangular flat plate member that is larger than the outer dimensions of the opening 231P in the X-axis and Y-axis directions. The reinforcing member 233 is fixed to the outer surface, the +Z side, of the frame 231 via fasteners such as screws or adhesive. A carbon plate made of carbon fiber reinforced plastic (CFRP) can be used as the reinforcing member 233.

[0049] The reinforcing member 233 may be fixed to the inside of the opening 231P, or it may be provided to fill the inside of the opening 231P, for example. For example, the reinforcing member 233 may be a resin member that fills the inside of the opening 231P. Also, the reinforcing member 233 may be configured to close only a part of the opening 231P, rather than the entire opening 231P.

[0050] By providing an opening 231P in the frame 231, X-rays irradiated from above the X-stage 23 can be allowed to pass through. This prevents the X-stage 23 from interfering with X-ray imaging.

[0051] As shown in Figure 3, the drive source (e.g., a motor) for the X-stage moving section 23M is fixed to the -Y side end of the frame 231. In this case, when the Y-stage 21 moves, the drive source pushes and pulls the frame 231 on one side (the -Y side), which can cause an uneven distribution of force on the frame 231 and potentially deform the frame 231. In contrast, by providing a reinforcing member 233 to the frame 231, the rigidity of the frame 231 can be improved, thereby suppressing deformation of the frame 231. Furthermore, since the reinforcing member 233 has an X-ray transparent material, it is possible to prevent the reinforcing member 233 from interfering with X-ray imaging.

[0052] In particular, by using a high-strength and lightweight carbon plate as the reinforcing member 233, it is possible to improve the rigidity of the frame 231 while suppressing weight increase. Furthermore, carbon has a very low X-ray absorption coefficient and hardly absorbs or scatters X-rays. Therefore, even if a carbon plate is attached to the opening 231P of the frame 231, it does not obstruct the passage of X-rays through the opening 231P. In addition, carbon is an expensive material and is difficult to process due to its high strength. Therefore, if the entire X-stage 23 were made of carbon, it would lead to increased costs. In contrast, as in this embodiment, costs can be reduced by using a metal such as aluminum or iron for the frame 231 with an opening. Therefore, with the X-stage 23, it is possible to achieve both the acquisition of clear X-ray images and the securing of rigidity of the stage section while maintaining an inexpensive configuration.

[0053] The Y-stage 21, the holding stage 25, and the Zθ stage 27 may also be composed of a frame with an opening and a reinforcing member fixed to the frame, similar to the X-stage 23. However, the Y-stage 21 is relatively larger than the X-stage 23. Therefore, the proportion of the total size of the opening required to allow X-rays to pass through is smaller than that of the X-stage 23. For this reason, the Y-stage 21 may only have an opening and no reinforcing member.

[0054] Returning to Figure 1, the Y-stage 21 has a reference scale SC1. The reference scale SC1 is located on the upper surface of the Y-stage 21. The reference scale SC1 is an index that indicates the reference when aligning the position of each element. The reference scale SC1 extends along the X-axis direction and has a scale marking. The scale markings of the reference scale SC1 are formed on a substrate such as glass from a material with high X-ray absorption, such as gold or lead, so that they can be photographed by the visible light camera 50 and the X-ray camera 60, respectively.

[0055] To form the exposure pattern in the correct position, the substrate 9 must be aligned with high precision. Especially in the case of a multilayer substrate, the patterns of each layer must be precisely superimposed to form the multilayer structure. The reference scale SC1 is used as an absolute reference point during this alignment process.

[0056] Figure 5 is a control block diagram of the exposure apparatus 1. The control unit 70 is a unit for controlling the operation of each part of the exposure apparatus 1. As shown in Figure 5, the control unit 70 is a computer equipped with a processor 71 such as a CPU (Central Processing Unit) and a memory 72 such as RAM (Random Access Memory) or ROM (Read Only Memory). The memory 72 may also include an auxiliary storage device such as a hard disk drive. The memory 72 stores a detection program P1 for detecting the marks 90 and an exposure program P2 for performing the exposure process. The detection program P1 and the exposure program P2 may be recorded on a recording medium that can be read by the control unit 70, which is a computer.

[0057] The control unit 70 is electrically connected to the Y-stage moving unit 21M, the X-stage moving unit 23M, the Zθ-stage 27, the visible light camera 50, the X-ray camera 60, the X-ray source moving unit 65, and the exposure unit 40, and is capable of communicating with them.

[0058] The control unit 70 of the exposure apparatus 1 performs alignment (positioning) of the substrate 9 based on each image obtained by capturing images with the X-ray camera 60. Next, the alignment process performed by the control unit 70 will be described.

[0059] <Alignment Process> Figure 6 is a flowchart of the alignment process. Figure 7 is a top view showing a substrate 9 on which multiple marks 90 are provided. The imaging field area 60R shown in Figure 7 conceptually represents the range that the X-ray camera 60 can image. The center of this imaging field area 60R corresponds to the position of the X-ray optical axis XL1.

[0060] As shown in Figure 7, the substrate 9 is provided with multiple marks 90. These marks 90 form a grid-like arrangement structure with spacing dx in the X-axis direction and spacing dy in the Y-axis direction. Here, a group of four marks 90 arranged in a row in the Y-axis direction is called a mark row ML. In Figure 7, the mark row ML is located on the substrate 9 from the -X side to the +X side. １ , ML ２ , ML ３ There are three rows of markers. In the design data, these rows of markers are arranged with a spacing of dx in the X-axis direction.

[0061] Based on the design data, the control unit 70 uses the X-ray camera 60 to photograph two marks 90 in the target column ML (mark sequence) whose positions are to be acquired (Figure 6: Pre-imaging process S1). Then, the control unit 70 calculates the approximate positions of the two marks 90 based on the images obtained in the pre-imaging process S1 (Figure 6: Approximate position calculation process S2). Furthermore, the control unit 70 moves the holding stage 25 based on the calculated approximate positions (Figure 6: Stage movement process S3). This movement is performed so that marks 90a and 90b approach the optical axis XL1 (Figure 2) in the X-axis direction, as will be described later. The movement of the holding stage 25 is achieved by linear movement by the Y-stage movement unit 21M and the X-stage movement unit 23M, and rotational movement by the Zθ stage 27. Following the stage movement process S3, the control unit 70 takes X-ray images of each mark 90 in the target column ML (Figure 6: Main imaging process S4). Then, based on the image obtained in the main shooting process S4, the position of each mark in the target mark sequence ML is calculated (Figure 6: Mark position calculation process S5). The positions of the marks 90 obtained by the mark position calculation process S5 are stored in the memory 72 as appropriate.

[0062] Figure 8A shows the first mark column ML １ This figure conceptually shows the pre-shooting process S1 for the following. Figure 8B shows the first mark column ML １ This figure conceptually shows the main shooting process S4 for the mark row ML. In the example shown in Figure 8A, in the pre-shooting process S1, the holding stage 25 is moved in the Y-axis direction to move the mark row ML １At the +Y end of the field of view, two adjacent marks 90a and 90b are photographed one by one. If both marks 90a and 90b fit within a single imaging field of view 60R, these marks 90a and 90b may be photographed only once.

[0063] During the pre-imaging process S1, the actual positions of the multiple marks 90 (shown by solid lines) are shifted in the X-axis and Y-axis directions, as well as tilted around the Z-axis, relative to their positions in the design data (shown by dashed lines). In other words, a positional error occurs in the marks 90 relative to the reference edge 9E of the substrate 9. Therefore, in the pre-imaging process S1, marks 90a and 90b are photographed off-center from the X-ray optical axis XL1 (the center of the imaging field of view 60R). Consequently, the positions of marks 90a and 90 calculated from the images obtained in the pre-imaging process S1 are approximate positions with low accuracy.

[0064] Therefore, in the stage movement process S3, the control unit 70 moves the holding stage 25 to bring the marks 90a and 90b closer to the optical axis XL1 in the X-axis direction. Specifically, the deviation between the approximate positions of the marks 90a and 90b and their positions in the design data is corrected by moving the stage. As a result, as shown in Figure 8B, each mark 90 is aligned with the position in the design data. In the imaging process S4, the holding stage 25 is stepped up by an interval Dy in the Y-axis direction (-Y direction) in conjunction with the imaging of each mark 90 by the X-ray camera 60. This step-by-step movement brings each mark 90 closer to the X-ray optical axis XL1 in the Y-axis direction. That is, imaging of each mark 90 is performed when each mark 90 is close to the optical axis XL1 in both the X-axis and Y-axis directions. By imaging in this optimal positional relationship, the mark position calculation process S5 can obtain the accurate position of the mark 90 from the obtained image. Therefore, high-precision positioning can be performed based on the obtained position of the mark 90.

[0065] Returning to FIG. 6, following the mark position calculation process S5, the control unit 70 determines whether the positions of all the marks 90 have been acquired (end determination step S6). When the positions of all the marks 90 have been acquired (Yes in the end determination step S6), the control unit 70 ends the alignment process. When there are marks 90 for which the positions have not been acquired (No in the end determination step S6), the control unit 70 moves the holding stage 25 in the X-axis direction in order to capture the unacquired marks 90 with the X-ray camera 60 (stage feed process S7). Then, the control unit 70 executes the pre-capture process S1 to the mark position calculation process S5 again. In this way, the control unit 70 acquires the positions of all the marks 90 by repeatedly executing the pre-capture process S1 to the mark position calculation process S5 for all the mark columns ML.

[0066] FIG. 9A is a diagram conceptually showing the pre-capture process S1 for the second mark column ML ２ FIG. 9B is a diagram conceptually showing the main capture process S4 for the second mark column ML ２ In the example shown in FIG. 9A, X-ray imaging is performed on two adjacent marks 90c and 90d at the -Y side end among the second mark column ML ２ Also, in the example shown in FIG. 9B, X-ray imaging is performed in order from the mark 90c at the -Y side end. That is, the feed direction (+Y direction) of the stage during imaging of the second mark column ML ２ is opposite to the feed direction (-Y direction) during imaging of the first mark column ML １ By performing X-ray imaging with such a stage feed, the movement of the holding stage 25 can be minimized. For this reason, the alignment process can be performed efficiently.

[0067] Based on the position of each mark 90 acquired by the alignment process, the control unit 70 controls the exposure unit 40 to perform pattern exposure on the substrate 9. For example, the control unit 70 may correct the shape of the pattern to be exposed on the substrate 9 based on the position coordinates of each mark 90. By performing exposure by the exposure unit 40 based on such correction data, exposure with less positional deviation can be realized.

[0068] As described above, according to this embodiment, in the alignment process, the stage is moved based on the approximate position of the mark 90 obtained in the pre-imaging, and X-ray imaging is performed with the mark 90 closer to the X-ray optical axis XL1. This suppresses fluctuations in the geometric magnification of the X-ray image caused by positional fluctuations of the mark 90 in the Z-axis direction within the substrate 9, thereby enabling accurate acquisition of the position of the mark 90. ​​Consequently, alignment accuracy can be improved.

[0069] Furthermore, in the above embodiment, the number of marks 90 whose approximate positions are obtained in the approximate position calculation process S2 (two in Figure 8A) is less than the number of marks 90 whose positions are obtained in the mark position calculation process S5 (four in Figure 8B). Therefore, the positions of the marks 90 can be obtained efficiently and with high accuracy.

[0070] The pre-imaging process S1 is for calculating the approximate position of mark 90. ​​On the other hand, the main imaging process S4 is for calculating the precise position of mark 90. ​​For this reason, the X-ray exposure time in the pre-imaging process S1 may be shorter than the exposure time in the main imaging process S4. By shortening the exposure time, the position of mark 90 can be acquired more efficiently.

[0071] <2. Modifications> Although embodiments have been described above, the present invention is not limited to those described above, and various modifications are possible.

[0072] For example, in the alignment process of the above embodiment, the approximate positions of two marks in the same mark sequence ML are calculated, but the approximate positions of three or more marks may be calculated. This allows for more accurate detection of positional misalignment of the marks 90, thereby enabling appropriate stage movement.

[0073] Alternatively, the approximate position of only one mark 90 may be calculated. However, by calculating the approximate positions of two or more marks 90, positional deviations of the marks 90 can be detected with high accuracy.

[0074] Furthermore, in the alignment process, it is not mandatory to perform the pre-shooting process S1 to the stage movement process S3 for all mark rows ML. For example, the first mark row ML １ Regarding this, the pre-shooting process S1 is executed, followed by the stage movement process S3, and the second and subsequent mark columns ML ２， ML ３ In this case, the pre-shooting process S1 and the stage movement process S3 may be omitted.

[0075] In the above embodiment, the case in which the substrate processing apparatus processes a glass substrate for a liquid crystal display device was described. However, the substrate to be processed may also be a substrate for electronic equipment such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a plasma display, a glass or ceramic substrate for a magnetic or optical disk, a glass substrate for an organic EL display, a glass substrate or silicon substrate for a solar cell, or other flexible substrates or printed circuit boards.

[0076] Although this invention has been described in detail, the above description is illustrative in all respects, and the invention is not limited thereto. It is understood that countless variations not illustrated can be conceived without falling outside the scope of this invention. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other.

[0077] 1: Exposure apparatus 9: Substrate 21: Y stage 21M: Y stage moving unit 23: X stage 23M: X stage moving unit 25: Holding stage 27: Zθ stage 40: Exposure unit 60: X-ray camera 61: X-ray source 63: X-ray detector 70: Control unit 90: Mark 213: Reinforcement member 231: Frame 231P: Aperture 233: Reinforcement member ML: Mark row XL1: Optical axis

Claims

1. Alignment apparatus comprising: a stage for holding a substrate on which marks are formed; an X-ray camera having an X-ray source positioned on one side of the stage for irradiating with X-rays and an X-ray detector positioned on the other side of the stage for detecting the X-rays; a stage moving unit for moving the stage; and a control unit for controlling the X-ray source and the stage moving unit, wherein the control unit performs: approximate position acquisition processing, which involves photographing the marks on the substrate held on the stage with the X-ray camera and acquiring the approximate positions of the marks; and position acquisition processing, which involves moving the stage so that the marks on the substrate are closer to the optical axis of the X-ray source based on the approximate positions, photographing the marks with the X-ray camera, and acquiring the positions of one or more marks.

2. An alignment apparatus according to claim 1, wherein the exposure time of the X-ray camera in the approximate position acquisition process is shorter than the exposure time of the X-ray camera in the position acquisition process.

3. An alignment device according to claim 1 or claim 2, wherein the number of marks whose approximate positions are acquired in the approximate position acquisition process is less than the number of marks whose positions are acquired in the position acquisition process.

4. Alignment apparatus according to any one of claims 1 to 3, wherein the approximate position acquisition process includes a process for acquiring the approximate positions of two or more marks, and the position acquisition process includes a process for moving the stage based on the approximate positions of the two or more marks.

5. Alignment apparatus according to any one of claims 1 to 4, wherein the stage moving unit is capable of moving the stage in a first direction and in a second direction intersecting the first direction, the substrate has a row of marks consisting of a plurality of marks arranged in the first direction, the approximate position acquisition process includes a process for acquiring the approximate positions of two or more marks in the row of marks, and the position acquisition process includes a process for moving the stage so that the two or more marks whose approximate positions have been acquired approach the optical axis of the X-ray source.

6. Alignment apparatus according to claim 5, wherein the substrate has a first row of marks arranged in a line and a second row of marks arranged in the first direction and separated from the first row of marks in the second direction, and the control unit performs the approximate position acquisition process and the position acquisition process for the first row of marks, then moves the stage in the second direction, and performs the approximate position acquisition process and the position acquisition process for the second row of marks.

7. An alignment apparatus according to any one of claims 1 to 6, wherein the stage comprises: a metal frame having an opening on its inner side; and an X-ray transparent reinforcing member provided in the frame to close at least a portion of the opening.

8. Alignment device according to claim 7, wherein the drive unit of the stage moving unit is fixed to the frame.

9. Alignment device according to claim 7 or claim 8, wherein the reinforcing member is a flat plate member fixed to the outer surface of the frame and closing the opening.

10. An exposure apparatus comprising: an alignment apparatus according to any one of claims 1 to 9; and an exposure unit for exposing the substrate.

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