Exposure method

Abstract

To provide a technique capable of properly calculating a position of an alignment mark from an x-ray image, even when the alignment mark formed inside a substrate is distanced from an optical axis of an X-ray source.SOLUTION: The position of a second stage 25 is adjusted so that the height of an upper surface of a substrate 9 in a Z-axis direction becomes a reference height Zh (first adjustment step S12). An X-ray camera 60 is moved by a depth Δz of an alignment mark 90 (second adjustment step S14). The alignment mark 90 is imaged by the X-ray camera 60 (imaging step S15). From the position of the alignment mark 90 in an X-ray image D1, the position of the alignment mark 90 in the X-axis and Y-axis directions is calculated (mark position calculation step S16). Based on the calculated position of the alignment mark, the substrate 9 is exposed (exposure step S18).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to an exposure method. [Background technology]

[0002] Conventionally, exposure apparatuses that expose a pattern onto the upper surface of a substrate for manufacturing a substrate such as a printed circuit board have been known. In this type of exposure apparatus, alignment marks formed on the substrate are detected, and the exposure position on the substrate is adjusted based on the positions of the alignment marks. For example, in Patent Document 1, the positions of alignment marks present inside the substrate are identified by capturing an image of the alignment marks using X-rays. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-022099 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when imaging an alignment mark using X-rays, the X-rays are emitted radially, resulting in differences in the magnification of the image depending on the X-ray irradiation position. In particular, in the case of a multilayer substrate, the alignment mark is formed inside the substrate, so deviations in the position and size of the alignment mark in the X-ray image occur depending on the depth of the alignment mark from the top surface. This deviation becomes larger the further away from the X-ray optical axis. Therefore, when an alignment mark formed inside the substrate is farther away from the X-ray optical axis, it is difficult to accurately calculate the position of the alignment mark.

[0005] An object of the present invention is to provide a technology that can properly calculate the position of an alignment mark formed inside a substrate from an X-ray image, even if the alignment mark is away from the optical axis of the X-ray source. [Means for solving the problem]

[0006] In order to solve the above problem, a first aspect is an exposure method including: a first adjustment step of adjusting the position of a stage holding a substrate so that the height of the top surface of the substrate in a first direction becomes a reference height; a depth acquisition step of acquiring the depth from the top surface of the substrate to an alignment mark inside the substrate in the first direction; a second adjustment step of, after the first adjustment step, moving an X-ray camera including an X-ray source and an X-ray detector relatively to the stage by the depth; an imaging step of, after the second adjustment step, imaging the alignment mark with the X-ray camera to obtain an X-ray image of the alignment mark; a mark position calculation step of calculating the position of the alignment mark in a second direction intersecting the first direction from the position of the alignment mark in the X-ray image; and an exposure step of exposing the substrate based on the position of the alignment mark calculated by the mark position calculation step.

[0007] A second aspect is the exposure method of the first aspect, wherein the reference height is a height of a reference mask that can be imaged by the X-ray camera.

[0008] A third aspect is the exposure method of the second aspect, further comprising, prior to the second adjustment step, a step of adjusting the height of the X-ray camera in the first direction to match the reference mask.

[0009] A fourth aspect is the exposure method according to the first or second aspect, wherein the imaging step is a step of simultaneously imaging a plurality of alignment marks with X-rays.

[0010] A fifth aspect is an exposure method of the first or second aspect, further comprising a correction step of correcting drawing data based on the position of the alignment mark calculated by the mark position calculation step, and the exposure step includes a step of performing exposure based on the corrected drawing data.

[0011] A sixth aspect is an exposure method including: a first adjustment step of adjusting the position of a stage holding the substrate so that the height of the top surface of the substrate in a first direction becomes a reference height; a step of acquiring the depth in the first direction from the top surface of the substrate to an alignment mark formed inside the substrate; after the first adjustment step, an imaging step of capturing an image of the alignment mark located inside the substrate with an X-ray camera to obtain an X-ray image of the alignment mark; a step of calculating the position of the alignment mark in a second direction intersecting the first direction based on the position of the alignment mark in the X-ray image and the depth; and a step of exposing the substrate based on the position of the alignment mark in the second direction. [Effects of the Invention]

[0012] According to the exposure methods of the first to fifth aspects, even if the alignment mark is provided inside the substrate, by moving the X-ray source and the X-ray detector relative to the substrate by the depth of the alignment mark, it is possible to perform X-ray photography in a state equivalent to when the alignment mark is formed on the upper surface of the substrate. This makes it possible to correct the positional deviation of the projection position of the alignment mark on the X-ray detector according to the depth of the alignment mark, thereby enabling the position of the alignment mark to be calculated with high accuracy.

[0013] According to the exposure method of the second aspect, the alignment marks can be X-ray photographed at a magnification that matches the reference mask, thereby enabling the positions of the alignment marks to be determined with high precision.

[0014] According to the exposure method of the fourth aspect, by imaging a plurality of alignment marks simultaneously with X-rays, the time required for alignment can be reduced compared to imaging the alignment marks one by one.

[0015] According to the exposure method of the sixth aspect, even if the alignment mark is formed inside the substrate, the position of the alignment mark can be calculated with high precision based on the X-ray image and the depth of the alignment mark. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing the overall configuration of an exposure apparatus. [Figure 2] FIG. 2 is a YZ plan view showing the alignment configuration of the exposure apparatus. [Figure 3] FIG. 2 is an XZ plan view showing the alignment configuration of the exposure apparatus. [Figure 4] FIG. [Figure 5] FIG. 2 is a control block diagram of the exposure apparatus. [Figure 6] FIG. 2 is a diagram conceptually illustrating functions realized in a control unit. [Figure 7] 5 is a flowchart showing the flow of operations of the exposure apparatus according to the first embodiment. [Figure 8] FIG. 2 is a diagram showing the positional relationship between an X-ray camera and a substrate. [Figure 9] FIG. 10 is a diagram showing a substrate with one surface mounted thereon as a comparison example. [Figure 10] FIG. 1 shows a 12-sided substrate. [Figure 11] 10 is a flowchart showing the flow of operations of the exposure apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the components described in the embodiment are merely examples and are not intended to limit the scope of the present invention. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary to facilitate understanding.

[0018] In FIG. 1 and the subsequent figures, an XYZ Cartesian coordinate system is defined to explain the positional relationships. Here, the X-axis direction and the Y-axis direction are defined as horizontal directions. The Y-axis direction and the X-axis direction are perpendicular to each other. The vertical direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction. In the following explanation, in the Z-axis direction, the +Z direction is defined as the vertically upward direction, and the -Z direction is defined as the vertically downward direction.

[0019] 1. First embodiment FIG. 1 is a perspective view showing the overall configuration of exposure apparatus 1. FIG. 2 is a YZ plan view showing the alignment configuration of exposure apparatus 1. FIG. 3 is an XZ plan view showing the alignment configuration of exposure apparatus 1. Exposure apparatus 1 is an apparatus that irradiates light onto the upper surface of substrate 9, which is coated with a photosensitive material, to expose a pattern onto the upper surface of substrate 9. Substrate 9 is, for example, a printed circuit board or a semiconductor substrate. For example, in the manufacturing process of a printed circuit board, a process of forming a layer on the upper surface of substrate 9 in another apparatus and a process of exposing a pattern onto the upper surface of substrate 9 in this exposure apparatus 1 are repeatedly performed. In this way, a multilayer printed circuit board (hereinafter also simply referred to as a "multilayer board") is manufactured.

[0020] As shown in FIG. 1, the exposure apparatus 1 includes a base 10, a gantry 15, a first stage 21, a first moving mechanism 23, a second stage 25, a second moving mechanism 27, an exposure unit 40, an X-ray camera 60, and a control unit 70.

[0021] The base 10 is a support platform that supports the gantry 15, first stage 21, first moving mechanism 23, second stage 25, second moving mechanism 27, exposure unit 40, and X-ray camera 60. The base 10 has a flat plate-like outer shape that extends along a horizontal plane. The base 10 is formed from stone material such as granite. The base 10 is fixed to the floor of the factory.

[0022] The base 10 has a rectangular shape when viewed from above. In the following, among the horizontal directions, the direction along the long side of the base 10 is the Y-axis direction, and the direction along the short side of the base 10 is the X-axis direction.

[0023] The gantry 15 is fixed to the upper surface of the base 10. The gantry 15 has a pair of legs 151 and a bridge portion 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 10. The bridge portion 152 connects the upper ends of the legs 151 to each other in the X-axis direction. A through hole 18 is formed between the upper surface of the base 10 and the gantry 15, allowing the substrate 9 to pass through in the Y-axis direction.

[0024] The first stage 21 is movable along the Y-axis direction. The first stage 21 has a flat plate-like outer shape. When viewed from above, the first stage 21 has a rectangular shape that is smaller than the base 10. The first stage 21 is disposed above the base 10 in a substantially horizontal position. The first stage 21 is made of a material such as carbon that is transmissive to X-rays irradiated from an X-ray source 61, which will be described later.

[0025] The first movement mechanism 23 is a mechanism for moving the first stage 21 in the Y-axis direction relative to the base 10 and the gantry 15. The first movement mechanism 23 is a linear motor mechanism having a pair of guide rails and a linear motor. The pair of guide rails guide the first stage 21 in the main scanning direction. The pair of guide rails are provided on the upper surface of the base 10 with a gap in 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 10 and a slider fixed to the underside of the first stage 21. When a drive signal is supplied from the control unit 70 to the linear motor, the slider moves along the stator in the Y-axis direction due to magnetic attraction and repulsion forces generated between the stator and slider. As a result, the first stage 21 moves in the Y-axis direction relative to the base 10. Note that the drive source of the first movement mechanism 23 is not limited to a linear motor. The first movement mechanism 23 may be, for example, a mechanism that converts the rotational motion of a servo motor into linear motion using a ball screw.

[0026] The second stage 25 is movable along the X-axis direction. The second stage 25 has a flat plate-like outer shape. When viewed from above, the second stage 25 has a rectangular shape that is smaller than the first stage 21. The second stage 25 is disposed above the first stage 21 in a substantially horizontal position. The second stage 25 is made of a material such as carbon that is transmissive to X-rays irradiated from an X-ray source 61, which will be described later.

[0027] The second movement mechanism 27 is a mechanism that moves the second stage 25 in the sub-scanning direction relative to the first stage 21. The second movement mechanism 27 is a linear motor mechanism that has a pair of guide rails and a linear motor. The pair of guide rails are rails that guide the second stage 25 in the sub-scanning direction. The pair of guide rails are provided on the upper surface of the first stage 21 with a gap between them in the main scanning direction. Each guide rail extends linearly along the sub-scanning direction. However, the second movement mechanism 27 is not limited to a linear motor mechanism and may be a ball screw mechanism.

[0028] The substrate 9 is supported in a substantially horizontal position on the upper surface of the second stage 25. The second stage 25 may have chuck pins for fixing the substrate 9 and a plurality of suction holes for adsorbing the substrate 9. The exposure apparatus 1 operates the first movement mechanism 23 and the second movement mechanism 27 to move the substrate 9 in the Y-axis direction (main scanning direction) and the X-axis direction (sub-scanning direction), respectively.

[0029] 2, the second stage 25 has a holding stage 250 and a third movement mechanism 251. The holding stage 250 is an upper part of the second stage 25, and has an upper surface that holds the substrate 9. The third movement mechanism 251 is a mechanism that moves the holding stage 250 in the Z-axis direction. The third movement mechanism 251 is configured with, for example, a ball screw mechanism or a linear motor mechanism, and is controlled by the control unit 70. Note that the exposure apparatus 1 may further include a mechanism that rotates the substrate 9 around an axis extending in the Z-axis direction.

[0030] Returning to FIG. 1, the exposure unit 40 is a unit that exposes the substrate 9 supported by the second 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 bridge portion 152 of the gantry 15. The plurality of heads 41 are arranged at intervals along the X-axis direction. Note that light sources other than laser oscillators, such as mercury lamps and LEDs, may also be used.

[0031] The laser oscillator 43 emits light in accordance with a drive signal supplied from the control unit 70. The light emitted from the laser oscillator 43 is introduced into each head 41 via an illumination optical system 42. A spatial modulator is provided inside each head 41. For example, a GLV (Grating Light Valve) (registered trademark), which is a diffraction grating type spatial light modulator, can be used as the spatial modulator. The light introduced into 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. Note that a spatial light modulator such as a DMD may be used instead of the GLV.

[0032] When the exposure apparatus 1 is in operation, the substrate 9 is moved by the first movement mechanism 23 and the second movement mechanism 27 while being irradiated with light from each head 41. As a result, a pattern is exposed onto the upper surface of the substrate 9.

[0033] FIG. 4 is a cross-sectional view of a substrate 9. The substrate 9 shown in FIG. 4 is a multilayer substrate having a plate-shaped substrate main body 91 and a plurality of upper layers 92 formed on the substrate main body 91. One or more alignment marks 90 are formed inside the substrate 9. The alignment marks 90 are, for example, holes formed in a copper foil layer included in the upper layer 92. The shape of the alignment marks 90 when viewed from above is, for example, circular. However, the alignment marks 90 may have other shapes, such as a rectangle or a cross.

[0034] As shown in Fig. 2, exposure apparatus 1 further includes two cameras 501 and 503. Cameras 501 and 503 are visible light cameras that capture images using visible light. Camera 501 is a camera for adjusting the distance between heads 41. Camera 503 is a camera for aligning exposure with respect to a substrate (e.g., a single-layer substrate) having an alignment mark on its upper surface.

[0035] The camera 501 is attached to the first stage 21 and can move in the Y-axis direction together with the first stage 21. The camera 503 is fixed to the base 10 and is attached to the bridge portion 152 of the gantry 15, for example.

[0036] The cameras 501 and 503 each have an imaging element such as a CCD or CMOS, and an optical system that introduces light to the imaging element. The cameras 501 and 503 may also have a light source that illuminates the imaging target. The cameras 501 and 503 transmit the captured visible light images 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. The cameras 501 and 503 may also be infrared cameras that capture images using infrared light.

[0037] The optical systems of the cameras 501 and 503 are preferably telecentric optical systems, which allow the cameras 501 and 503 to acquire visible light images with small changes in magnification from the center of the field of view to the edges of the field of view.

[0038] 3, the exposure apparatus 1 further includes a fourth movement mechanism 31 and a fifth movement mechanism 32. The fourth movement mechanism 31 moves the camera 501 in the X-axis direction relative to the first stage 21. The fifth movement mechanism 32 moves the camera 503 in the X-axis direction relative to the gantry 15. The fourth movement mechanism 31 and the fifth movement mechanism 32 are configured, for example, with a ball screw mechanism or a linear motor mechanism, and are controlled by a control unit 70. The control unit 70 moves the camera 501 to match the positions of the multiple heads 41 in the X-axis direction, thereby causing the camera 501 to capture images of the light emitted from the multiple heads 41.

[0039] The X-ray camera 60 is a camera that takes images using X-rays. The X-ray camera 60 takes an image of, for example, an alignment mark 90 formed inside the substrate 9 using X-rays. As shown in FIGS. 2 and 3 , the X-ray camera 60 has an X-ray source 61 and an X-ray detector 63.

[0040] The X-ray source 61 is a unit that irradiates the substrate 9 with X-rays, which are radiation. The X-ray source 61 is attached to the bridge portion 152 of the gantry 15. The X-ray source 61 emits X-rays downward. That is, the X-ray source 61 emits X-rays from above the substrate 9 toward the substrate 9. The X-rays emitted from the X-ray source 61 spread radially, pass through the substrate 9, the second stage 25, and the first stage 21 in this order, and are irradiated onto the X-ray detector 63.

[0041] The X-ray detector 63 is an X-ray image sensor that detects X-rays irradiated from the X-ray source 61. The X-ray detector 63 is fixed to the upper surface of the base 10. Therefore, the position of the X-ray detector 63 relative to the X-ray camera 60 is fixed. The X-ray detector 63 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 X-rays detected at each position on the detection surface. Then, the X-ray detector 63 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.

[0042] As shown in FIG. 2, the exposure apparatus 1 includes a sixth movement mechanism 33 that moves the X-ray source 61 in the Z-axis direction, and a seventh movement mechanism 34 that moves the X-ray detector 63 in the Z-axis direction. The sixth movement mechanism 33 and the seventh movement mechanism are configured by, for example, a linear motor mechanism or a ball screw mechanism, and are controlled by the control unit .

[0043] 3, the exposure apparatus 1 further includes an eighth movement mechanism 36 that moves the X-ray source 61 in the X-axis direction, and a ninth movement mechanism 37 that moves the X-ray detector 63 in the X-axis direction. The eighth movement mechanism 36 and the ninth movement mechanism 37 are configured by, for example, a linear motor mechanism or a ball screw mechanism, and are controlled by a control unit 70.

[0044] It is not essential that the X-ray source 61 and the X-ray detector 63 be moved independently in the Z-axis direction. That is, the X-ray source 61 and the X-ray detector 63 may be moved integrally by a common moving mechanism. The same applies to the movement of the X-ray source 61 and the X-ray detector 63 in the X-axis direction.

[0045] The exposure apparatus 1 has a reference mask Ms. The reference mask Ms is an index that indicates a reference when aligning the position of each element. In this example, the reference mask Ms extends along the X-axis direction and has scales that indicate dimensions. The scales on the reference mask Ms are formed of a material with high X-ray absorption, such as gold or lead, on a substrate such as glass so that they can be imaged by the visible light cameras 501 and 503 and the X-ray camera 60. However, the exposure apparatus 1 may also have a reference mask for each of the cameras 501 and 503 and a reference mask for the X-ray camera 60. The alignment of the cameras 501 and 503 and the X-ray camera 60 is performed based on the images obtained by imaging the reference mask Ms with each camera.

[0046] FIG. 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 FIG. 5, the control unit 70 is a computer including a processor 71 such as a CPU (Central Processing Unit) and a memory 72 such as a RAM (Random Access Memory) or a 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 alignment mark 90 and an exposure program P2 for performing exposure processing. The detection program P1 and the exposure program P2 are The control unit 70, which is a computer, may be recorded on a readable recording medium. The control unit 70 is electrically connected to the first moving mechanism 23, the second moving mechanism 27, the third moving mechanism 251, the fourth moving mechanism 31, the fifth moving mechanism 32, the sixth moving mechanism 33, the seventh moving mechanism 34, the eighth moving mechanism 36, the ninth moving mechanism 37, the exposure unit 40, the cameras 501 and 503, the X-ray source 61, and the X-ray detector 63.

[0047] Fig. 6 is a diagram conceptually showing the functions realized in the control unit 70. As shown in Fig. 6, the control unit 70 has an alignment unit 74 and an exposure control unit 75. The alignment unit 74 also has a depth acquisition unit 740, a mark position calculation unit 741, and a correction unit 742.

[0048] The function of the alignment unit 74 is realized by the control unit 70 executing the detection program P1. The exposure apparatus 1 operates as a detection device that detects the position of the alignment mark 90 formed on the substrate 9 in order to align the exposure position using the alignment unit 74. The function of the exposure control unit 75 is realized by the control unit 70 operating in accordance with the exposure program P2 described above. The exposure apparatus 1 performs an exposure process on the substrate 9 by controlling the operation of the first movement mechanism 23, the second movement mechanism 27, and the exposure unit 40 using the exposure control unit 75.

[0049] The depth acquisition unit 740 acquires the depth Δz of the alignment mark 90 formed inside the substrate 9 from the top surface of the substrate 9. To take into account the contraction and expansion of the substrate 9, the depth Δz is desirably calculated from the designed position of the alignment mark 90 in the Z-axis direction (design value) and the measured value of the thickness d of the substrate 9. The thickness d of the substrate 9 is obtained by measuring the distance from the top surface of the holding stage 250 of the second stage 25 to the top surface of the substrate 9, for example, using the camera 503. Specifically, by moving the holding stage 250 in the Z-axis direction while keeping the camera 503 fixed, a position where the focus of the camera 503 is aligned with the top surface of the holding stage 250 and the top surface of the substrate 9 (for example, a mark or circuit pattern other than the alignment mark 90) can be found. Note that an autofocus mechanism (not shown) provided in the head 41 may be used instead of the camera 503. The autofocus mechanism is configured to detect the height of the top surface of the substrate 9, which is the surface to be exposed, and focus light on the detected height. In addition, in calculating the depth Δz, it is not essential to use the measured value of the thickness d of the substrate 9, and only the design value may be used.

[0050] As will be described later, the alignment unit 74 controls the sixth movement mechanism 33 and the seventh movement mechanism 34 to raise the X-ray source 61 and the X-ray detector 63 in the +Z direction by the depth Δz acquired by the depth acquisition unit 740. This allows the magnification of the X-ray image obtained when the alignment mark 90 is imaged by the X-ray camera 60 to match the magnification when the alignment mark 90 is formed on the upper surface of the substrate 9. This will be described later.

[0051] The mark position calculation unit 741 calculates the position of the alignment mark 90 in real space (the position in the X-axis direction and the position in the Y-axis direction) by detecting the position of the alignment mark 90 on the X-ray image D1. The correction unit 742 corrects the drawing data based on the position of the alignment mark 90. ​​The drawing data is data expressing a drawing pattern to be exposed on the upper surface of the substrate 9, and is stored in the memory 72.

[0052] <Operation of exposure equipment> A series of processes for detecting the position of an alignment mark 90 formed on a substrate 9 and exposing the substrate 9 based on the detection results will be described. FIG. 7 is a flowchart showing the flow of operations of the exposure apparatus 1 according to the first embodiment. FIG. 8 is a diagram showing the positional relationship between the X-ray camera 60 and the substrate 9. Note that the flowchart shown in FIG. 7 is executed under the control of the control unit 70 unless otherwise specified. Also, the procedure shown in FIG. 7 is one example and can be changed as desired. The same applies to the subsequent flowcharts.

[0053] The depth acquisition unit 740 of the alignment unit 74 acquires the depth Δz of the alignment mark 90 from the upper surface of the substrate (depth acquisition step S11). As described above, the depth acquisition unit 740 calculates the depth Δz based on the design value of the mark position of the alignment mark 90 and the actual measured value of the thickness of the substrate 9.

[0054] Next, the control unit 70 controls the third movement mechanism 251 to adjust the height of the second stage 25 (more specifically, the holding stage 250) so that the height of the upper surface of the substrate 9 in the Z-axis direction (first direction) becomes the reference height Zh (see FIG. 8), which is the height of the reference mask Ms (first adjustment step S12). Specifically, the camera 503 is aligned in advance with the reference mask Ms. Then, while the third movement mechanism 251 moves the second stage 25 in the Z-axis direction, the camera 503 captures an image of a mark or circuit pattern other than the alignment mark 90 formed on the upper surface of the substrate 9. As a result, the height of the upper surface of the substrate 9 is adjusted to the reference height Zh.

[0055] Next, the control unit 70 adjusts the heights of the X-ray source 61 and the X-ray detector 63 in the Z-axis direction so that the projection magnification (geometric magnification) of the reference mask Ms on the X-ray camera 60 becomes the desired magnification M (X-ray camera adjustment step S13). Through the first adjustment step S12 and the X-ray camera adjustment step S13, the positional relationship between the X-ray camera 60 and the substrate 9 becomes the positional relationship shown in FIG.

[0056] Here, if the distance DD from the X-ray source 61 (X-ray focal point) to the X-ray detector 63 in the Z-axis direction and the distance OD1 from the X-ray source 61 (X-ray focal point) to the reference mask Ms in the Z-axis direction are taken as the magnification M, then the magnification M is expressed by the following equation: M = DD / OD1 (1)

[0057] If the alignment mark 90 is located on the upper surface of the substrate 9, the alignment mark 90 will be at the reference height Zh, and therefore the projection position MI′ of the alignment mark 90 on the X-ray detector 63 will be a position according to the magnification M. That is, if the distance from the optical axis Ax (center of the field of view) of the X-ray source 61 to the alignment mark 90 is LO, and the distance from the intersection OA of the X-ray detector 63 and the optical axis Ax to the projection position MI′ of the alignment mark 90 is LD′, the following equation holds: LO = 1 / M * LD′ = OD1 / DD * LD′ (2)

[0058] However, when the alignment mark 90 is formed inside the substrate 9, the distance LD from the optical axis Ax to the projection position MI becomes smaller than the aforementioned distance LD′ by a deviation amount ΔD, depending on the depth Δz of the alignment mark 90 from the upper surface of the substrate, as shown in Fig. 8. In other words, the magnification of the alignment mark 90 in the X-ray image D1 deviates from the known magnification M, making it difficult to accurately calculate the distance LD. Note that the depth Δz is the difference (Δz = OD2 - OD1) between the distance OD2 from the X-ray source 61 to the alignment mark 90 in the Z-axis direction and the distance OD1 from the X-ray source 61 to the upper surface of the substrate 9 (i.e., the reference height Zh) in the Z-axis direction.

[0059] Therefore, in this embodiment, the alignment unit 74 controls the sixth movement mechanism 33 and the seventh movement mechanism 34 to move the X-ray source 61 and the X-ray detector 63 by a depth Δz while maintaining the distance DD in a direction in which the X-ray source 61 approaches the substrate 9 (second adjustment step S14). Then, the alignment unit 74 acquires an X-ray image D1 by capturing an image of the alignment mark 90 with X-rays (X-ray imaging step S15). By the second adjustment step S14, the position of the alignment mark 90 as viewed from the X-ray camera 60 becomes equivalent to a state in which the alignment mark 90 is on the upper surface of the substrate 9, i.e., at the reference height Zh. In other words, the projection position of the alignment mark 90 becomes MI′, and the magnification of the alignment mark 90 in the X-ray image D1 can be made to match the previously set M-times.

[0060] The mark position calculation unit 741 of the alignment unit 74 calculates the mark position of the alignment mark 90 in real space from the position of the alignment mark 90 in the X-ray image D1 (mark position calculation step S16). Specifically, the mark position calculation unit 741 calculates the distance LO by substituting the distance LD′ obtained from the X-ray image D1 and the magnification M into the above formula (2).

[0061] The distance LD' is expressed by the following equation, where PR is the size of one pixel of the X-ray detector 63, and PX is the number of pixels from the optical axis Ax to the projected image of the alignment mark 90. LD′ = PX * PR (3)

[0062] By performing such calculations for the X-axis direction and the Y-axis direction, the positions of the alignment mark 90 in the X-axis direction and the Y-axis direction are calculated. The X-axis direction and the Y-axis direction correspond to a second direction that intersects with the Z-axis direction (first direction).

[0063] The correction unit 742 corrects the drawing data based on the mark positions calculated in the mark position calculation step S16 (correction step S17). The correction unit 742 translates or deforms the drawing pattern indicated by the drawing data in accordance with the deviation of the mark positions from the design values. As a result, correction data is generated that represents a drawing pattern that corresponds to the actual deformation of the substrate 9, etc.

[0064] When the correction data is generated, the exposure control unit 75 of the control unit 70 controls the operation of the first moving mechanism 23, the second moving mechanism 27, and the exposure unit 40 based on the correction data, thereby performing an exposure process on the substrate 9 (exposure step S18). As a result, a drawing pattern is formed on the upper surface of the substrate 9.

[0065] Next, we will explain the case where alignment is performed on a multi-faceted substrate 9 in order to manufacture multiple small substrates from a single substrate. Fig. 9 is a diagram showing a substrate 9 with one face attached. Fig. 10 is a diagram showing a substrate 9 with twelve faces attached. The alignment marks 90 shown on the substrate 9 in each figure are present inside each substrate 9. Also, the dashed lines indicate the observation field (X-ray imaging field).

[0066] In the example shown in FIG. 9 , multiple alignment marks 90 cannot be included in the observation field simultaneously. Therefore, by placing one alignment mark 90 in the center of the observation field (near the optical axis Ax), the deviation ΔD (see FIG. 8 ) can be sufficiently reduced. On the other hand, as shown in FIG. 10 , in the case of multi-surface mounting, two or four alignment marks 90 on different surfaces can be included in the observation field simultaneously. However, when multiple alignment marks 90 are simultaneously X-rayed, the positions of at least some of the alignment marks 90 will be shifted from the optical axis Ax, resulting in a deviation ΔD. Therefore, as described above, by offsetting the X-ray source 61 and the X-ray detector 63 downward by the depth Δz of the alignment marks 90 while maintaining the distance DD, the alignment marks 90 are positioned equivalent to the reference height Zh, enabling accurate alignment of the exposure position. Furthermore, by simultaneously X-raying multiple alignment marks 90, the alignment time can be reduced compared to X-raying each alignment mark 90 one by one.

[0067] 2. Second embodiment Next, a second embodiment will be described. In the following description, elements having the same functions as elements already described will be given the same reference numerals or reference numerals with an additional alphabetical character, and detailed description thereof may be omitted.

[0068] FIG. 11 is a flowchart showing the flow of operations of the exposure apparatus 1 according to the second embodiment. In the first embodiment, as shown in FIG. 7, the X-ray source 61 and the X-ray detector 63 are moved by a depth Δz relative to the substrate 9 in the second adjustment step S14. In this embodiment, as shown in FIG. 11, the second adjustment step S14 is not performed, and an X-ray imaging step S15 is performed. Then, in a mark position calculation step S16a, the mark position of the alignment mark 90 is calculated based on the X-ray image D1 and the depth Δz. Then, after the mark position calculation step S16a, a correction step S17 and an exposure step S18 are performed, as in the first embodiment.

[0069] Specifically, in the mark position calculation step S16a, the distance OD2 from the X-ray source 61 to the alignment mark 90 in the Z-axis direction is calculated by the following equation. OD2 = OD1 + Δz (4)

[0070] Further, the distance LO from the optical axis Ax to the alignment mark 90 is calculated by the following equation. LO = OD2 / DD * LD (5)

[0071] The distance LD is expressed by the following equation, where PR is the size of one pixel of the X-ray detector 63, and PX is the number of pixels from the optical axis Ax to the projected image of the alignment mark 90. LD = PX * PR (6)

[0072] As described above, in this embodiment, the step of moving the X-ray camera 60 by the depth Δz relative to the substrate 9 (second adjustment step S14) can be omitted, and therefore the time required for alignment for exposure can be reduced.

[0073] <3. Modifications> Although the embodiments have been described above, the present invention is not limited to the above and various modifications are possible.

[0074] For example, in the second adjustment step S14 of the first embodiment, the X-ray camera 60 is moved by a depth Δz in the direction in which the X-ray source 61 approaches the substrate 9. However, the substrate 9 may also be moved by a depth Δz in the direction in which the substrate 9 approaches the X-ray source 61. In this case, the upper surface of the substrate 9 is positioned above the reference height Zh. Therefore, after the second adjustment step S14 and before the exposure step S18, the upper surface of the substrate 9 (surface to be exposed) is adjusted to the reference height Zh.

[0075] Although the present invention has been described in detail, the above description is merely illustrative in all respects and does not limit the present invention. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present invention. The configurations described in the above embodiments and variations can be combined or omitted as appropriate as long as they are not mutually inconsistent. [Explanation of symbols]

[0076] 9: Circuit board 25: Second Stage 60: X-ray camera 61 :X-ray source 63: X-ray detector 250: Holding stage Ax: Optical axis D1:X-ray image Ms: Reference mask

Claims

1. An exposure method comprising: a first adjustment step of adjusting a position of a stage that holds the substrate so that the height of an upper surface of the substrate in a first direction is equal to a reference height; a depth acquiring step of acquiring a depth from an upper surface of the substrate to an alignment mark inside the substrate in the first direction; a second adjusting step of moving an X-ray camera including an X-ray source and an X-ray detector relative to the stage by the depth after the first adjusting step; an imaging step of imaging the alignment mark with the X-ray camera after the second adjusting step to obtain an X-ray image of the alignment mark; a mark position calculation step of calculating a position of the alignment mark in a second direction intersecting the first direction from the position of the alignment mark in the X-ray image; an exposure step of exposing the substrate based on the positions of the alignment marks calculated in the mark position calculation step; An exposure method comprising:

2. 2. The exposure method according to claim 1, The exposure method, wherein the reference height is a height of a reference mask that can be imaged by the X-ray camera.

3. 3. The exposure method according to claim 2, a step of adjusting the height of the X-ray camera in the first direction to match the reference mask before the second adjustment step; The exposure method further comprises:

4. 3. The exposure method according to claim 1 or 2, The exposure method, wherein the imaging step is a step of simultaneously imaging a plurality of alignment marks with X-rays.

5. 3. The exposure method according to claim 1 or 2, a correction step of correcting drawing data based on the positions of the alignment marks calculated in the mark position calculation step; further comprising The exposure method, wherein the exposure step includes a step of performing exposure based on the corrected drawing data.

6. An exposure method comprising: a first adjustment step of adjusting a position of a stage that holds the substrate so that the height of an upper surface of the substrate in a first direction is equal to a reference height; acquiring a depth in the first direction from an upper surface of the substrate to an alignment mark formed inside the substrate; an imaging step of imaging the alignment mark located inside the substrate with an X-ray camera after the first adjusting step to obtain an X-ray image of the alignment mark; calculating a position of the alignment mark in a second direction intersecting with the first direction based on the position of the alignment mark in the X-ray image and the depth; exposing a substrate based on the position of the alignment mark in the second direction; An exposure method comprising:

Images