Alignment device and exposure device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SCREEN HOLDINGS CO LTD
- Filing Date
- 2026-01-15
- Publication Date
- 2026-07-30
Smart Images
Figure JP2026001066_30072026_PF_FP_ABST
Abstract
Description
Alignment Device and Exposure Device
[0001] The subject matter disclosed in this specification relates to an alignment device and an exposure device.
[0002] Conventional exposure devices have a visible light alignment system for observing marks on the substrate surface and correcting the exposure position. This alignment system is calibrated by a reference scale mounted on the device. Particularly in the case of a multilayer substrate, since the inside or the bottommost surface of the substrate serves as the reference for exposure, in order to perform accurate exposure, the substrate needs to be drilled to expose the reference mark and alignment is performed using the visible light alignment system. However, this drilling process takes time and leads to an increase in the manufacturing process.
[0003] Patent Document 1 discloses a positioning technique that uses marks or structures inside the substrate as the reference for the exposure position. In Patent Document 1, a reference mark located in the inner layer of a multilayer substrate is photographed with X-rays, and the position of the reference mark is obtained from the acquired X-ray photographic image for exposure alignment. Specifically, while moving the XY stage that holds the substrate, the reference mark is positioned within the field of view of the X-ray camera, and the position of the mark is calculated from the X-ray reference mark photographic image.
[0004] Japanese Patent Application Laid-Open No. 2004-012903
[0005] However, in Patent Document 1, when obtaining the positional relationship between the exposure device and the reference mark, there is no reference on the device side. Therefore, the positional relationship between the exposure device and the reference mark is calculated based on the coordinate information of the XY stage. However, in this method, the accuracy of obtaining the positional relationship between the reference mark and the device side depends on the accuracy of the XY stage.
[0006] Particularly, when the stage is movable in both the X and Y directions, there is a problem that the accuracy of the measurement result tends to decrease because errors in the movement accuracy of each movement mechanism of the stage are added to the detected coordinate information. Therefore, there is a demand for a technique to achieve more accurate alignment (positioning) of the substrate.
[0007] An object of the present invention is to provide a technique capable of achieving high-precision alignment of a substrate disposed on a moving stage.
[0008] To solve the above problems, the first embodiment is an alignment apparatus comprising: a base portion; a first stage provided on the base portion and movable in a first direction relative to the base portion; a first reference scale provided on the first stage; a first stage moving unit for moving the first stage in a first direction relative to the base portion; a second stage provided on the first stage and movable in a second direction intersecting the first direction relative to the first stage, and holding a substrate; a second stage moving unit for moving the second stage in a second direction relative to the first stage; a second reference scale provided on the second stage; and the first reference scale, the second base The apparatus comprises an imaging unit for imaging a quasi-scale and marks provided on the substrate held in the second stage, and a control unit for controlling the first stage moving unit, the second stage moving unit, and the imaging unit, wherein the control unit can perform a first reference scale imaging process for imaging the first reference scale with the imaging unit, a second reference scale imaging process for imaging the second reference scale with the imaging unit, a mark imaging process for imaging marks provided on the substrate with the imaging unit, and a position coordinate calculation process for calculating the position coordinates of the marks based on the images obtained by the first reference scale imaging process, the second reference scale imaging process, and the mark imaging process.
[0009] The second embodiment is an alignment apparatus according to the first embodiment, wherein the control unit performs the second reference scale imaging process and the mark imaging process while fixing the position of the second stage in the second direction relative to the first stage.
[0010] A third embodiment is the alignment apparatus of the first embodiment, wherein the imaging unit has an X-ray camera.
[0011] A fourth embodiment is an alignment apparatus according to the third embodiment, wherein the imaging unit further comprises a visible light camera, the first reference scale imaging process includes imaging the first reference scale with the visible light camera, the second reference scale imaging process includes imaging the second reference scale with the visible light camera and the X-ray camera respectively, the mark imaging process includes imaging the mark with the X-ray camera, and the coordinate calculation process includes a relative position calculation process that calculates the relative position of the second reference scale with respect to the first reference scale based on the images obtained by the visible light camera in the first reference scale imaging process and the second reference scale imaging process.
[0012] The fifth aspect is the alignment apparatus of the fourth aspect, wherein the first reference scale and the second reference scale are formed of thin films, and the film thickness of the first reference scale is smaller than that of the second reference scale.
[0013] The sixth aspect is an alignment device according to the fourth aspect, wherein the first reference scale is made of a light metal.
[0014] The seventh embodiment is an exposure apparatus comprising an alignment apparatus according to the first or second embodiment, and an exposure unit for exposing the substrate held on the second stage.
[0015] According to the first to seventh embodiments, the relative position coordinates of the mark with respect to the second reference mark can be calculated by photographing the second reference scale and the mark. Furthermore, the position coordinates of the second reference scale with respect to the first reference scale can be determined by photographing the first reference scale and the second reference scale. Therefore, regardless of the positional accuracy of the second stage, the relative position coordinates of the mark with respect to the first reference scale can be obtained with high accuracy.
[0016] According to the alignment device of the second embodiment, the occurrence of positional errors caused by the movement of the second stage between the image of the second reference scale and the image of the mark is suppressed. Therefore, the relative position coordinates of the mark with respect to the second reference scale can be captured with high accuracy.
[0017] According to the alignment apparatus of the third embodiment, marks formed inside the substrate can be photographed.
[0018] According to the alignment device of the fourth embodiment, by photographing the first reference scale and the second reference scale with a visible light camera, a clearer image can be obtained than when photographing with an X-ray camera. Therefore, the relative position of the second reference scale with respect to the first reference scale can be obtained with higher precision.
[0019] According to the alignment device of the fifth embodiment, the scale accuracy of the first reference scale can be improved by reducing the film thickness of the first reference scale.
[0020] This is a perspective view showing the overall configuration of the exposure apparatus according to the embodiment. This is a control block diagram of the exposure apparatus. This is a flowchart of the alignment process. This is a schematic plan view showing the imaging field area of the X-ray camera, the first reference scale, the second reference scale, and the displacement of the substrate during the alignment process. This is a schematic side view showing the X-ray camera that images the first reference scale. This is a schematic side view showing the X-ray camera that images a mark provided on the substrate. This is a schematic side view showing the visible light camera that images the first reference scale. This is a schematic side view showing the visible light camera that images the second reference scale. This is a schematic side view showing the X-ray camera that images the second reference scale. This is a schematic side view showing the X-ray camera that images a mark on the substrate.
[0021] 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.
[0022] <1. First 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.
[0023] 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 table 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, X-ray camera 60, and control unit 70 of the exposure apparatus 1 constitute an alignment apparatus.
[0024] 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.
[0025] 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.
[0026] The Y-stage 21 (first stage) 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. In a top view, the outer shape of the Y-stage 21 is rectangular, smaller than the base portion 10.
[0027] The Y-stage moving unit 21M (first stage moving unit) 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.
[0028] The X-stage 23 (second stage) 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. When viewed from above, its outer shape is a rectangle smaller than that of the Y-stage 21.
[0029] The X-stage moving unit 23M (second stage moving unit) is capable of controlling 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 also be a ball screw mechanism.
[0030] The holding table 25 is a component that holds the substrate 9. The holding table 25 is positioned on the X stage 23 via the Zθ stage 27. The holding table 25 has a plurality of suction holes on its upper part, and holds the substrate 9 by sucking air through these suction holes. The holding table 25 may also have chuck pins for fixing the substrate 9.
[0031] The Zθ stage 27 is fixed on the X stage 23. The Zθ stage 27 is configured such that the holding table 25 can be controlled to move along the Z-axis relative to the X stage 23, and can also be controlled to rotate about the θ axis extending along the Z-axis.
[0032] The Y-stage 21, X-stage 23, holding table 25, and Zθ-stage 27 are made of a material such as carbon that can transmit X-rays irradiated from the X-ray source 61 of the X-ray camera 60.
[0033] The exposure apparatus 1 moves the substrate 9 held on the holding table 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.
[0034] The exposure unit 40 is a unit that exposes a substrate 9 supported by a holding table 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 a bridging portion 152 in one of the two gantry units 15, the gantry unit 15 located on the +Y side. The plurality of heads 41 are arranged between the two gantry units 15 in the Y-axis direction. The plurality of heads 41 are arranged spaced apart from each other along the X-axis direction.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] The visible light camera 50 is configured to move along the X-axis direction by a visible light camera movement unit (not shown) provided on the bridging 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. Various methods can be used to drive the visible light camera movement unit, such as a linear motor system, a ball screw system, or a belt drive system.
[0039] The X-ray camera 60 is a camera that takes images using X-rays. The X-ray camera 60 has an X-ray source 61 and two X-ray detectors 63. The X-ray source 61 is installed on the -Y side of the bridging portion 152 of the -Y side gantry 15 of the two gantry 15s. The X-ray source 61 irradiates an X-ray beam downwards. The X-ray camera 60 is an example of an imaging unit.
[0040] The two X-ray detectors 63 are positioned below the X-ray source 61 and are fixed to the upper surface of the base 10. The two X-ray detectors 63 are spaced apart in the X-axis direction. Each 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 detectors 63 generate an X-ray image based on the intensity of the X-rays detected at each position on the detection surface and transmit 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.
[0041] The X-ray source 61 is configured to be movable in the X-axis direction by an X-ray source moving unit 65 provided in 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 drive method can be adopted.
[0042] As shown in FIG. 1, the Y stage 21 has a first reference scale 211. The X stage 23 has a second reference scale 231. The first reference scale 211 is disposed on the upper surface of the Y stage 21. The second reference scale 231 is disposed on the upper surface of the X stage 23. The second reference scale 231 is disposed away from the +Y side of the holding table 25. The first reference scale 211 is disposed away from the +Y side of the second reference scale 231. The positions (heights) of the first reference scale 211 and the second reference scale 231 in the Z-axis direction are substantially the same.
[0043] The first reference scale 211 and the second reference scale 231 are indicators showing the reference for aligning the positions of the respective elements. The first reference scale 211 and the second reference scale 231 extend along the X-axis direction and have graduations indicating the scale. The graduations of the first reference scale 211 and the second reference scale 231 are formed of a material with a high X-ray absorption rate such as gold or lead on a substrate such as glass so that they can be photographed by the visible light camera 50 and the X-ray camera 60, respectively.
[0044] In order to form the exposure pattern at an accurate position, it is necessary to align the position of the substrate 9 with high precision. Particularly in the case of a multilayer substrate, in order to form a multilayer structure, it is necessary to accurately overlap the patterns of each layer. The first reference scale 211 and the second reference scale 231 are used as absolute reference points during the alignment.
[0045] Figure 2 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. 2, 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 include an auxiliary storage device such as a hard disk drive. The memory 72 stores a detection program P1 for detecting the mark 90 and an exposure program P2 for performing an exposure process. The detection program P1 and the exposure program P2 may be recorded on a recording medium readable by the control unit 70 which is a computer.
[0046] The control unit 70 is electrically connected to the Y-stage moving unit 21M, the X-stage moving unit 23M, the visible light camera 50, the X-ray camera 60, the X-ray source moving unit 65, and the exposure unit 40, and can communicate with them.
[0047] The control unit 70 of the exposure apparatus 1 performs alignment (positioning) of the substrate 9 based on each image obtained by photographing with the visible light camera 50 and the X-ray camera 60. Next, the alignment process of the control unit 70 will be described.
[0048] <Alignment Process> Figure 3 is a diagram showing a flowchart of the alignment process. Figure 4 is a plan view schematically showing the imaging field region 60R of the X-ray camera 60, the first reference scale 211, the second reference scale 231, and the displacement of the substrate 9 in the alignment process. The imaging field region 60R indicates the range of X-rays incident on the X-ray detector 63 of the X-ray camera 60. Also, FIG. 5A is a schematic side view showing the X-ray camera 60 that photographs the first reference scale 211. FIG. 5B is a schematic side view showing the X-ray camera 60 that photographs the mark 90 provided on the substrate 9.
[0049] The substrate 9 shown in Figures 5A and 5B is a multilayer substrate having multiple layers on a substrate body, and has one or more marks 90 formed inside. The marks 90 are alignment reference marks and are marks that can be photographed with an X-ray camera 60. The marks 90 are, for example, holes formed in the copper foil layer of the substrate 9. The shape of the marks 90 in a top view is, for example, circular. However, the marks 90 may have shapes other than circular, such as rectangles or crosses.
[0050] In the following description, the substrate 9 is provided with multiple marks 90. As shown in Figure 4, the multiple marks 90 are arranged in a grid pattern with intervals Dx and Dy between them in both the X-axis and Y-axis directions, and a total of nine marks 90 are provided on the substrate 9 in three rows in the Y-axis direction and three columns in the X-axis direction. Note that it is not necessary to have multiple marks 90; there may be just one.
[0051] First, the control unit 70 moves the X-stage 23 to match the position of the unphotographed mark 90 in the X-axis direction (Figure 3: X-axis direction movement process S1). This movement causes the position of the unphotographed mark 90 to coincide with the position of the imaging field area 60R of the X-ray camera 60 in the X-axis direction. By moving the X-stage 23 and the Y-stage 21 only in the Y-axis direction while keeping the X-stage 23 fixed relative to the Y-stage 21, it is possible to photograph the first reference scale 211, the second reference scale 231, and the mark 90 using the X-axis direction movement process S1.
[0052] Following the X-axis movement process S1, the control unit 70 photographs the first reference scale 211 with the X-ray camera 60 (Figure 3: First reference scale imaging process S2). Specifically, as shown in Figure 4, the control unit 70 controls the Y-stage movement unit 21M to move the Y-stage 21 in the Y-axis direction so that the first reference scale 211 enters the imaging field of view 60R of the X-ray camera 60. As a result, as shown in Figure 5A, the first reference scale 211 is positioned below the X-ray source 61. In this state, the control unit 70 photographs the first reference scale 211 with the X-ray camera 60 and acquires an X-ray image of the first reference scale 211 (first reference scale image).
[0053] Following the first reference scale imaging process S2, the control unit 70 images the second reference scale 231 with the X-ray camera 60 (Figure 3: second reference scale imaging process S3). Specifically, as shown in Figure 4, the Y stage 21 is moved in the +Y direction so that the second reference scale 231 enters the imaging field of view 60R. This amount of movement is specifically the distance between the first reference scale 211 and the second reference scale 231 in the Y axis direction. Once the movement of the Y stage 21 is complete, the control unit 70 images the second reference scale 231 with the X-ray camera 60 and acquires an X-ray image of the second reference scale 231 (second reference scale image).
[0054] Following the second reference scale imaging process S3, the control unit 70 images a row of marks 90 arranged along the Y-axis (Figure 3: Mark imaging process S4). Specifically, as shown in Figure 4, the control unit 70 moves the Y-stage 21 in the +Y direction so that the mark 90 closest to the second reference scale 231 is within the imaging field of view 60R. As a result, as shown in Figure 5B, the marks 90 are positioned below the X-ray source 61. In this state, the control unit 70 images the marks 90 with the X-ray camera 60 and acquires an X-ray image (mark image) of the marks 90. The control unit 70 also alternates between X-ray imaging of the marks 90 and moving the Y-stage 21 in the +Y direction by an interval Dy. This completes the X-ray imaging of the three marks 90 arranged in a row.
[0055] Following the mark imaging process S4, the control unit 70 determines whether X-ray imaging of all marks 90 has been completed (Figure 3: determination process S5). If it is determined that X-ray imaging of all marks 90 has been completed (Yes in determination process S5), the marks 90 execute the position coordinate calculation process S11, which will be described later.
[0056] In the determination process S5, if it is determined that there are uncaptured marks 90 (No in the determination process S5), the control unit 70 moves the X-stage 23 in the X-axis direction to match the position of the uncaptured marks 90 in the X-axis direction (Figure 3: X-axis direction movement process S6). Specifically, as shown in Figure 4, the control unit 70 moves the X-stage 23 in the X-axis direction (in the -X direction in Figure 4) by an interval Dx relative to the Y-stage 21. As a result, the shooting field of view area 60R is aligned with the uncaptured marks 90 that are adjacent to the last captured marks 90 in the X-axis direction.
[0057] Following the X-axis movement process S6, the control unit 70 photographs a row of marks 90 aligned along the Y-axis (Figure 3: Mark photography process S7). Specifically, similar to the mark photography process S4, the control unit 70 alternately performs X-ray photography of the marks 90 and movement of the Y-stage 21 in the -Y direction by an interval Dy. This completes the X-ray photography of the three marks 90 aligned in a row.
[0058] Following the mark imaging process S7, the control unit 70 performs X-ray imaging of the second reference scale 231 (Figure 3: Second reference scale imaging process S8). Specifically, as shown in Figure 4, the Y stage 21 is moved in the -Y direction so that the second reference scale 231 enters the imaging field of view 60R. Once the movement of the Y stage 21 is complete, the control unit 70 uses the X-ray camera 60 to image the second reference scale 231 and acquire an X-ray image of the second reference scale 231.
[0059] Following the second reference scale imaging process S8, the control unit 70 images the first reference scale 211 with the X-ray camera 60 (Figure 3: First reference scale imaging process S9). Specifically, as shown in Figure 4, the Y stage 21 is moved in the -Y direction so that the first reference scale 211 enters the imaging field of view area 60R. Once the movement of the Y stage 21 is complete, the control unit 70 images the first reference scale 211 with the X-ray camera 60.
[0060] Following the first reference scale imaging process S9, the control unit 70 determines whether X-ray imaging of all marks 90 has been completed (Figure 3: determination process S10). The marks 90 perform the position coordinate calculation process S11, which will be described later. If the determination process S10 determines that there are marks 90 that have not been photographed (No in the determination process S10), the control unit 70 performs the X-axis direction movement process S1 again.
[0061] In the determination process S10, if it is determined that X-ray imaging of all marks 90 has been completed (Yes in the determination process S10), the control unit 70 calculates the position coordinates of each mark 90 (more specifically, the relative position coordinates with respect to the first reference scale 211) based on the acquired images.
[0062] Specifically, in the position coordinate calculation process S11, the positions of the first reference scale 211, the second reference scale 231, and the mark 90 on each image obtained in the first reference scale shooting process S2, the second reference scale shooting process S3, and the mark shooting process S4 are calculated using known methods such as pattern matching. In addition, the relative positional relationship between the images is calculated from the amount of movement of the Y stage 21 when acquiring each image (more specifically, the target movement amount given to the Y stage movement unit 21M). From these calculation results, the position coordinates of the mark 90 captured in the mark shooting process S4 are calculated. Similarly, the position coordinates of the mark 90 captured in the mark shooting process S7 are calculated using the images obtained in the mark shooting process S7, the second reference scale shooting process S8, and the first reference scale shooting process S9, along with the amount of movement of the Y stage.
[0063] The relative position coordinates of each mark 90 with respect to the second reference scale 231 can be obtained from the image of the second reference scale 231 obtained in the second reference scale imaging process S3 and the images of each mark 90 obtained in the mark imaging process S4. In addition, the relative position of the second reference scale 231 with respect to the first reference scale 211 can be obtained from the image of the first reference scale 211 obtained in the first reference scale imaging process S2 and the image of the second reference scale 231 obtained in the second reference scale imaging process S3. Therefore, regardless of the positional accuracy of the X stage 23 with respect to the Y stage 21, the relative position coordinates of the marks 90 with respect to the first reference scale 211 can be obtained with high accuracy.
[0064] Furthermore, the X-stage 23 is fixed relative to the Y-stage 21 from the second reference scale imaging process S3 to the mark imaging process S4. This suppresses the occurrence of positional errors caused by the movement of the X-stage 23 between the images of the second reference scale 231 and the mark 90. Therefore, the relative position coordinates of the mark 90 with respect to the second reference scale 231 can be calculated with high accuracy.
[0065] Furthermore, the X-stage 23 is fixed relative to the Y-stage 21 during the period from the mark acquisition process S7 to the second reference scale acquisition process S8. This suppresses the occurrence of positional errors caused by the movement of the X-stage 23 between the images of the second reference scale 231 and the mark 90. Therefore, the relative position coordinates of the mark 90 with respect to the second reference scale 231 can be calculated with high accuracy.
[0066] Furthermore, if it is necessary to move the X-ray source 61 in order to photograph multiple marks 90 at different positions in the X-axis direction during the alignment process, the control unit 70 may control the X-ray source moving unit 65 to move the X-ray source 61 during the alignment process. In this case, the control unit 70 may measure the movement error caused by the X-ray source moving unit 65 based on the X-ray image of the first reference scale 211, and correct the position coordinates of the marks 90 in the position coordinate calculation process S11, taking into account the measured movement error.
[0067] The control unit 70 adjusts the position of the substrate 9 based on the position coordinates of each mark 90 obtained by the alignment process. For example, the control unit 70 corrects the tilt of the substrate in the horizontal plane (XY plane) by controlling the Zθ stage 27. The control unit 70 may also correct the shape of the pattern data to be exposed on the substrate 9 based on the position coordinates of each mark 90. By having the exposure unit 40 perform exposure based on such corrected data, exposure with minimal positional misalignment can be achieved.
[0068] <2. Second Embodiment> Next, a second embodiment will be described. In the following description, elements having the same function as those already described will be given the same reference numeral or a reference numeral with an additional alphabetic character, and detailed descriptions may be omitted.
[0069] In the first embodiment, alignment processing is performed using only the X-ray camera 60, but a visible light camera 50 may also be used. Figure 6A is a schematic side view showing the visible light camera 50 that photographs the first reference scale 211. Figure 6B is a schematic side view showing the visible light camera 50 that photographs the second reference scale 231. Figure 6C is a schematic side view showing the X-ray camera 60 that photographs the second reference scale 231. Figure 6D is a schematic side view showing the X-ray camera 60 that photographs the mark 90 on the substrate 9.
[0070] In this embodiment, the control unit 70 uses the visible light camera 50 to capture visible light images of the first reference scale 211 and the second reference scale 231 during the first reference scale imaging processes S2, S9 and the second reference scale imaging processes S3, S8 shown in Figure 3 (Figures 6A and 6B). The control unit 70 also uses the X-ray camera 60 to capture X-ray images of the second reference scale 231 during the second reference scale imaging processes S3, S8 (Figure 6C). Furthermore, the control unit 70 uses the X-ray camera 60 to capture X-ray images of the marks 90 on the substrate 9 during the mark imaging processes S4, S7 (Figure 6D).
[0071] When the first reference scale 211 and the second reference scale 231 are imaged with X-rays, the scale markings of these reference scales must be made of a material that absorbs X-rays well (a heavy metal such as Au). If the scale markings of the reference scales are made of a light metal such as chromium (Cr), the low X-ray absorption rate will result in insufficient contrast when imaged with X-rays. Furthermore, if the scale markings are made of Au, the film thickness of the markings must be increased to obtain sufficient contrast during X-ray imaging. However, increasing the film thickness makes it impossible to ensure sufficient accuracy in line width and scale interval of the scale markings, making it unusable as an absolute scale.
[0072] The first reference scale 211 is formed from a thin film of a light metal, such as Cr. The second reference scale 231 is formed from a thin film of a heavy metal, such as Au. This reduces manufacturing costs compared to forming the first reference scale 211 from a heavy metal such as Au. Furthermore, the film thickness of the first reference scale 211 is smaller than that of the second reference scale 231. This improves the scale accuracy of the first reference scale 211.
[0073] In this embodiment, the first reference scale 211 is precisely fabricated using a Cr thin film or the like, and photographed with a visible light camera 50. Furthermore, the second reference scale 231 is also photographed with the visible light camera 50 to obtain the relative positions of both scales. In addition, the relative positions of the second reference scale 231 and each mark 90 are obtained by imaging them with an X-ray camera 60. As a result, the relative position coordinates of each mark 90 can be accurately obtained using the first reference scale 211 as a reference.
[0074] <3. Modifications> Although embodiments have been described above, the present invention is not limited to those described above, and various modifications are possible.
[0075] For example, if mark 90 is a mark that can be photographed with the visible light camera 50, it may be photographed with the visible light camera 50 instead of the X-ray camera 60. In this case, in the alignment process shown in Figure 3, the control unit 70 may photograph all of the first reference scale 211, the second reference scale 231, and mark 90 with the visible light camera 50.
[0076] Furthermore, the imaging unit is not limited to a visible light camera 50 or an X-ray camera 60; an infrared camera or the like may also be used.
[0077] 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.
[0078] 1: Exposure apparatus 9: Substrate 10: Base unit 21: Y-stage (first stage) 21M: Y-stage moving unit (first stage moving unit) 23: X-stage (second stage) 23M: X-stage moving unit (second stage moving unit) 40: Exposure unit 50: Visible light camera (imaging unit) 60: X-ray camera (imaging unit) 70: Control unit 90: Mark 211: First reference scale 231: Second reference scale
Claims
1. An alignment device comprising: a base portion; a first stage provided on the base portion and movable in a first direction relative to the base portion; a first reference scale provided on the first stage; a first stage moving portion for moving the first stage in the first direction relative to the base portion; a second stage provided on the first stage and movable in a second direction intersecting the first direction relative to the first stage, and holding a substrate; a second stage moving portion for moving the second stage in the second direction relative to the first stage; a second reference scale provided on the second stage; an imaging portion for imaging the first reference scale, the second reference scale, and a mark provided on the substrate held by the second stage; and a control unit for controlling the first stage moving portion, the second stage moving portion, and the imaging portion, wherein the control unit comprises: a first reference scale imaging process for imaging the first reference scale with the imaging portion; a second reference scale imaging process for imaging the second reference scale with the imaging portion, An alignment device capable of performing a mark imaging process in which a mark provided on the substrate is imaged by the imaging unit, and a position coordinate calculation process in which the position coordinates of the mark are calculated based on the images obtained by the first reference scale imaging process, the second reference scale imaging process, and the mark imaging process.
2. Alignment apparatus according to claim 1, wherein the control unit performs the second reference scale imaging process and the mark imaging process while fixing the position of the second stage in the second direction relative to the first stage.
3. Alignment apparatus according to claim 1 or claim 2, wherein the imaging unit has an X-ray camera.
4. Alignment apparatus according to claim 3, wherein the imaging unit further comprises a visible light camera, the first reference scale imaging process includes imaging the first reference scale with the visible light camera, the second reference scale imaging process includes imaging the second reference scale with the visible light camera and the X-ray camera, the mark imaging process includes imaging the mark with the X-ray camera, and the coordinate calculation process includes a relative position calculation process that calculates the relative position of the second reference scale with respect to the first reference scale based on the images obtained by the visible light camera in the first reference scale imaging process and the second reference scale imaging process.
5. Alignment apparatus according to claim 4, wherein the first reference scale and the second reference scale are formed of thin films, and the film thickness of the first reference scale is smaller than that of the second reference scale.
6. Alignment apparatus according to claim 4 or claim 5, wherein the first reference scale is made of a light metal.
7. An exposure apparatus comprising: an alignment apparatus according to any one of claims 1 to 6; and an exposure unit for exposing the substrate held on the second stage.