Wafer bonding device and wafer bonding method

Abstract

A substrate bonding device (1) comprises a control unit (80) that acquires the state of inclination of at least one of a first stage (51) and a second stage (61) on the basis of the degree of focus of an overlap image (G) in which a first reference mark (MA1) and a second reference mark (MA2) imaged by a reference mark imaging unit (72) that images the first reference mark (MA1) and the second reference mark (MA2) overlap, the first reference mark (MA1) and the second reference mark (MA2) overlapping when viewed from the vertical direction.

Description

Substrate bonding apparatus and substrate bonding method

[0001] The present invention relates to a substrate bonding apparatus and a substrate bonding method, and more particularly to a substrate bonding apparatus and a substrate bonding method that include a first stage that holds a first substrate and a second stage that holds a second substrate.

[0002] A substrate bonding apparatus including a first stage for holding a first substrate and a second stage for holding a second substrate is known. Such a substrate bonding apparatus is disclosed, for example, in Japanese Patent Application Laid-Open No. 2014-168089.

[0003] The aforementioned Japanese Patent Application Laid-Open Publication No. 2014-168089 discloses a substrate superposition apparatus (substrate bonding apparatus) including a first stage for holding a first substrate, a second stage for holding a second substrate disposed opposite the first substrate, a spherical pedestal disposed below the first stage, and a drive device for driving the spherical pedestal. This substrate superposition apparatus is capable of adjusting the tilt of the first stage relative to a horizontal plane by driving the spherical pedestal with the drive device. This substrate superposition apparatus also includes a first interferometer for detecting the tilt of the first substrate held on the first stage and a second interferometer for detecting the tilt of the second substrate held on the second stage. The first interferometer detects the tilt of the first substrate based on a change in the distance to the first substrate held on the first stage when the first stage is moved relative to the first interferometer. Similarly to the first interferometer, the second interferometer detects the tilt of the second substrate based on a change in the distance to the second substrate held by the second stage when the second stage is moved relative to the second interferometer. The first and second stages are then moved relatively in the horizontal direction so that the first and second substrates face each other. Based on the detected tilt of the first and second substrates, the spherical base is driven by the driving device to adjust the tilt of the first stage relative to the horizontal plane so that the first and second substrates are parallel to each other. The first and second stages are then moved in directions approaching each other, thereby bonding the first and second substrates.

[0004] JP 2014-168089 A

[0005] However, in JP 2014-168089 A, after the tilt of the first substrate and the tilt of the second substrate are detected, the first stage and the second stage are moved relatively in the horizontal direction so that the first substrate and the second substrate face each other at a horizontal joining position. That is, the position where the tilt of the first substrate and the tilt of the second substrate are detected is different from the horizontal joining position of the first substrate and the second substrate. Therefore, due to the influence of the relative horizontal movement of the first stage and the second stage, the relative tilt relationship between the first stage and the second stage may be different between the position where the tilt is detected and the state where the first stage and the second stage are positioned so that the first substrate and the second substrate are positioned at the horizontal joining position. In this case, when the first substrate and the second substrate are facing each other at the horizontal joining position, even if the tilt adjustment is performed based on the tilt of the first substrate and the tilt of the second substrate detected before the horizontal movement, the first substrate and the second substrate will no longer be parallel to each other.

[0006] One object of the present invention is to provide a substrate bonding apparatus and a substrate bonding method that can more accurately obtain information about the inclination of the first stage and the second stage when the first substrate and the second substrate are facing each other at a horizontal bonding position.

[0007] A substrate bonding apparatus according to a first aspect of the present invention comprises a first stage capable of holding a first substrate and on which a first reference mark is arranged, a second stage capable of holding a second substrate and on which a second reference mark is arranged, a reference mark imaging unit that images the first reference mark and the second reference mark from the vertical direction while the first stage and the second stage are arranged so that the first reference mark and the second reference mark overlap when viewed from the vertical direction, and a control unit that acquires the tilt state of at least one of the first stage and the second stage based on the degree of focus of an overlapping image, which is an image of the overlapping first reference mark and the second reference mark imaged by the reference mark imaging unit.

[0008] According to the first aspect of the present invention, information on the inclination of the first stage and the second stage can be obtained when the first stage and the second stage are opposed to each other, so that information on the inclination of the first stage and the second stage when the first substrate and the second substrate are in a horizontal joining position can be obtained more accurately.

[0009] In the substrate bonding apparatus according to the first aspect, preferably, a plurality of first fiducial marks are arranged on the first stage, a plurality of second fiducial marks are arranged on the second stage so as to correspond to the plurality of first fiducial marks, and the control unit acquires the tilt state based on the degree of focus of overlapping images of a plurality of sets of corresponding first fiducial marks and second fiducial marks. With this configuration, since a plurality of first fiducial marks and a plurality of second fiducial marks are arranged, the tilt state can be acquired at a plurality of locations on the first stage and the second stage. As a result, information on the direction of tilt of the entire first stage and the second stage can be obtained based on the tilt state at the plurality of locations.

[0010] In the substrate bonding apparatus according to the first aspect, the control unit preferably executes control to acquire the tilt state based on a change in brightness value of an edge portion of at least one of the first fiducial mark and the second fiducial mark in the overlapping image. When the overlapping image is in focus, the change in brightness value of the edge portion is large, and when the overlapping image is out of focus, the change in brightness value of the edge portion is small. This allows the control unit to easily acquire the tilt state based on the change in brightness value of the edge portion.

[0011] In the substrate bonding apparatus according to the first aspect, the control unit preferably estimates, as the tilt state, an amount of vertical deviation of at least one of the first stage and the second stage from a reference horizontal plane, based on a plurality of overlapping images previously captured by the reference mark imaging unit in an in-focus state and an out-of-focus state and the overlapping image currently captured by the reference mark imaging unit. With this configuration, the amount of vertical deviation of at least one of the first stage and the second stage can be estimated without providing a separate sensor for detecting tilt, etc.

[0012] In this case, preferably, a plurality of first reference marks are arranged on the first stage, a plurality of second reference marks are arranged on the second stage so as to correspond to the plurality of first reference marks, and the control unit estimates the amount of vertical deviation for each pair of corresponding first and second reference marks. With this configuration, since a plurality of first reference marks and a plurality of second reference marks are arranged, it is possible to obtain the amount of vertical deviation at a plurality of locations on the first stage and the second stage.

[0013] In the substrate bonding apparatus that estimates the amount of vertical misalignment for each pair of corresponding first and second fiducial marks, preferably, the control unit causes the display unit to display a message urging the user to adjust at least one of the first and second stages when the amount of vertical misalignment for at least one of the plurality of pairs is equal to or greater than a threshold misalignment amount, thereby making it easy to recognize that tilt adjustment of the substrate bonding apparatus is necessary.

[0014] In the substrate bonding apparatus that estimates the amount of vertical deviation for each pair of corresponding first and second reference marks, preferably, the control unit causes the display unit to display the amount of vertical deviation for each of the plurality of pairs when the amount of vertical deviation for at least one of the plurality of pairs is equal to or greater than a deviation threshold. With this configuration, the amount of vertical deviation is displayed on the display unit, so that a maintenance worker can easily determine by visually checking the display unit how much tilt adjustment should be performed at which location on at least one of the first stage and the second stage, thereby efficiently performing the tilt adjustment work.

[0015] In the substrate bonding apparatus that estimates the amount of misalignment in the up-down direction for each pair of corresponding first and second reference marks, the control unit preferably stops the bonding operation of the first substrate and the second substrate when the amount of misalignment of at least one pair of the plurality of pairs is equal to or greater than the misalignment threshold. With this configuration, if the amount of misalignment of at least one pair is equal to or greater than the misalignment threshold during operation of the substrate bonding apparatus, the control unit automatically stops the bonding operation, thereby preventing the bonding operation from being continued in a state where the first stage and the second stage are not parallel to each other.

[0016] In the substrate bonding apparatus according to the first aspect, preferably, at least one of the first stage and the second stage includes a base portion and a stack portion stacked on the base portion, and an adjustment sheet member for adjusting the tilt of at least one of the first stage and the second stage can be arranged between the base portion and the stack portion. With this configuration, the tilt of at least one of the first stage and the second stage can be easily adjusted simply by placing the adjustment sheet member between the base portion and the stack portion.

[0017] A substrate bonding method according to a second aspect of the present invention comprises the steps of: positioning the first stage and the second stage so that, when viewed from the vertical direction, a first reference mark provided on the first stage holding the first substrate and a second reference mark provided on the second stage holding the second substrate overlap; capturing an image of the overlapping first reference mark and second reference mark from the vertical direction; and acquiring the tilt state of at least one of the first stage and the second stage based on the degree of focus of an overlapping image, which is an image in which the captured first reference mark and second reference mark overlap.

[0018] According to the substrate bonding method of the second aspect of the present invention, it is possible to obtain information about the tilt of the first stage and the second stage when the first stage and the second stage are opposed to each other, thereby providing a substrate bonding method that can more accurately obtain information about the tilt of the first stage and the second stage when the first substrate and the second substrate are in a horizontal bonding position.

[0019] According to the present invention, as described above, it is possible to more accurately obtain information about the tilt of the first stage and the second stage when the first substrate and the second substrate are in a horizontal joining position.

[0020] 1 is a block diagram showing the configuration of a substrate bonding apparatus according to an embodiment; FIG. 2 is a perspective view showing the configuration of a bonding unit according to an embodiment; FIG. 3 is a side view of an upper stage (first stage) of a bonding unit according to an embodiment; FIG. 4 is a side view of an upper stage (first stage) and a lower stage (second stage) of a bonding unit according to an embodiment; FIG. 5 is a top view of the upper stage (first stage) of a bonding unit according to an embodiment; FIG. 6 is a view showing an upper reference mark (first reference mark) according to an embodiment; FIG. 7 is a top view of the lower stage (second stage) of a bonding unit according to an embodiment; FIG. 8 is a view showing a lower reference mark (second reference mark) according to an embodiment; FIG. 9 is a top view of the upper stage of a bonding unit according to an embodiment; FIG. 10 is a view showing an upper alignment mark (first alignment mark) arranged on the first substrate; FIG. 11 is a top view of a second substrate (lower substrate); FIG. 12 is a view showing a lower alignment mark (second alignment mark) arranged on the second substrate; and FIG. 13 is a view showing a process flow of a substrate bonding apparatus according to an embodiment. FIG. 14 is a view for explaining an alignment mark / reference mark detection process (a process of detecting a lower alignment mark and a lower reference mark) of the process flow of a substrate bonding apparatus according to an embodiment. 1 is a diagram illustrating an alignment mark / reference mark detection step (a step of detecting an upper alignment mark and an upper reference mark) in the process flow of the substrate bonding apparatus according to an embodiment. FIG. 2 is a diagram illustrating an alignment step in the process flow of the substrate bonding apparatus according to an embodiment. FIG. 3 is a diagram illustrating a substrate bonding step in the process flow of the substrate bonding apparatus according to an embodiment. FIG. 4 is a diagram illustrating an inspection step in the process flow of the substrate bonding apparatus according to an embodiment. FIG. 5 is a flow diagram illustrating a method for acquiring the tilt state of a stage of the substrate bonding apparatus according to an embodiment. FIG. 6 is a diagram illustrating a brightness gradient in an overlapping image of an upper reference mark (first reference mark) and a lower reference mark (second reference mark). FIG. 7 is a diagram illustrating overlapping images in an in-focus state and an out-of-focus state stored in a memory unit. FIG. 8 is a diagram illustrating an upper stage and a lower stage in a state where the overlapping images are in focus. FIG. 9 is a diagram illustrating an upper stage and a lower stage in a state where the overlapping images are out-of-focus (when the lower stage is tilted).FIG. 1 is a diagram showing the upper stage and lower stage in a state where the overlapping images are out of focus (the upper stage is tilted); FIG. 2 is a diagram showing a state where a message is displayed on the display unit to prompt the maintenance worker to request that at least one of the upper stage and the lower stage be adjusted; FIG. 3 is a diagram showing a state where a message is displayed on the display unit to prompt the maintenance worker to perform an adjustment operation (parallel adjustment operation) to adjust at least one of the upper stage and the lower stage from an inclined state to a horizontal state (parallel state); FIG. 4 is a diagram showing an image displayed on the display unit when the adjustment operation of the upper stage and the lower stage is not required; and FIG. 5 is a diagram for explaining the operation of adjusting the tilt of the lower stage by arranging an adjustment sheet member.

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings.

[0022] [Embodiment] The configuration of a substrate bonding apparatus 1 according to this embodiment will be described with reference to Figure 1. In the following description, the up-down direction is referred to as the Z direction. The upward direction is referred to as the Z1 direction, and the downward direction is referred to as the Z2 direction. The direction perpendicular to the Z direction is referred to as the X direction. One side of the X direction is referred to as the X1 direction, and the other side is referred to as the X2 direction. The direction perpendicular to the Z direction and the X direction is referred to as the Y direction. One side of the Y direction is referred to as the Y1 direction, and the other side is referred to as the Y2 direction.

[0023] The substrate bonding apparatus 1 is an apparatus that bonds a first substrate W1 (upper substrate) and a second substrate W2 (lower substrate). Hereinafter, the first substrate W1 and the second substrate W2 will be collectively referred to as the substrate W. The substrate W may be made of a silicon wafer, a compound semiconductor wafer, a glass substrate, or the like, and may have elements formed thereon. The substrate bonding apparatus 1 includes a bonding unit 5 and a display unit 31. The substrate bonding apparatus 1 may also include a plasma processing unit for activating the surfaces (bonding surfaces) of the substrates W by plasma processing, a cleaning unit for cleaning the surfaces of the substrates W with a cleaning liquid, and a transport robot for transporting the substrates W between the units.

[0024] The display unit 31 is, for example, a liquid crystal display, an organic EL display, a micro LED display, etc. The display unit 31 includes a display unit 31 a attached to the substrate bonding apparatus 1 itself and a display unit 31 b such as a portable tablet terminal.

[0025] (Joining Unit) Next, the structure of the joining unit 5 will be described in detail with reference to FIGS.

[0026] As shown in FIG. 2 , the bonding unit 5 includes an upper stage 51, a lower stage 61, and a base 70. The bonding unit 5 also includes an alignment mark imaging unit 71, a reference mark imaging unit 72, and an inspection imaging unit 73. The bonding unit 5 also includes a bonding unit control unit 80. The bonding unit 5 is housed, for example, in a chamber. The upper stage 51 is an example of a "first stage" in the claims, and the lower stage 61 is an example of a "second stage" in the claims. The bonding unit control unit 80 is an example of a "control unit" in the claims.

[0027] The pedestal 70 supports the upper stage 51 and the lower stage 61. The pedestal 70 is disposed, for example, on the floor of a clean room in which the substrate bonding apparatus 1 is disposed. As shown in FIG. 3 , a gate-shaped frame 64 is provided on the pedestal 70. A Z-direction linear motor 64a is attached to each of two pillars of the frame 64, and a shaft 65b is attached to the Z-direction linear motor 64a. The upper stage 51 is supported by the shaft 65b. The Z-direction linear motor 64a attached to the frame 64 moves the shaft 65b in the Z direction, thereby raising and lowering the upper stage 51 in the Z direction. In addition, a rotation motor 65a is provided on the shaft 65b, and the upper stage 51 can be turned upside down by driving the rotation motor 65a.

[0028] 4, the upper stage 51 includes an upper chuck 51a, an upper rotation motor 51b, an upper base unit 51c, an upper stack unit 51d, and an upper reference mark MA1. The upper base unit 51c is an example of a "base unit" in the claims, and the upper stack unit 51d is an example of a "stack unit" in the claims. The upper reference mark MA1 is an example of a "first reference mark" in the claims.

[0029] The upper chuck 51a is, for example, a vacuum chuck or an electrostatic chuck. As shown in Fig. 5, the upper chuck 51a has, for example, a disk shape. As shown in Fig. 4, the upper rotation motor 51b is an electric motor that rotates the disk-shaped upper chuck 51a about a central axis L1. The upper base 51c supports the upper chuck 51a and the upper stack unit 51d. The upper base 51c can be inverted by rotating about an axis L2 by being driven by the rotation motor 65a.

[0030] As shown in Fig. 4, the upper laminate 51d is laminated on the upper base 51c. In this embodiment, an adjustment sheet member 90 (see Fig. 29) for adjusting the tilt of the upper stage 51 can be arranged between the upper base 51c and the upper laminate 51d. The upper base 51c and the upper laminate 51d are fixed together by, for example, a fastening member (not shown). Details of the tilt adjustment will be described later.

[0031] As shown in FIG. 5, the upper reference marks MA1 are disposed on the upper stage 51. For example, four upper reference marks MA1 are disposed on the surface of the upper stack 51d. The upper reference marks MA1 are formed on a transparent quartz plate member 51e. For example, two of the four upper reference marks MA1 are formed on one rectangular plate member 51e. The remaining two upper reference marks MA1 are each formed on one square plate member 51e. The four upper reference marks MA1 are disposed at the four corners of the square-shaped upper stack 51d. As shown in FIG. 6, the upper reference mark MA1 is formed by, for example, two rectangular portions ma1. The two rectangular portions ma1 are diagonally spaced apart from each other.

[0032] 4, the lower stage 61 includes a lower chuck 61a, a lower rotation motor 61b, a lower base 61c, a lower stack 61d, and a lower reference mark MA2. The lower base 61c is an example of a "base" in the claims, and the lower stack 61d is an example of a "stack" in the claims. The lower reference mark MA2 is an example of a "second reference mark" in the claims.

[0033] As shown in FIG. 4 , the lower chuck 61a is, for example, a vacuum chuck or an electrostatic chuck. The lower chuck 61a has, for example, a disk shape (see FIG. 7 ). The lower rotation motor 61b is an electric motor that rotates the disk-shaped lower chuck 61a around the central axis L3, as shown in FIG. 4 . The lower base 61c supports the lower chuck 61a and the lower stack 61d. The lower base 61c has, for example, a box shape. The lower base 61c is supported by an XY stage 62 (see FIG. 2 ). As shown in FIG. 2 , the XY stage 62 includes an X-direction linear slider 62a and a Y-direction linear slider 62b. The X-direction linear slider 62a moves the lower stage 61 along the X direction, and the Y-direction linear slider 62b moves the lower stage 61 along the Y direction.

[0034] As shown in Fig. 4, the lower laminate 61d is laminated on the lower base 61c. In this embodiment, an adjustment sheet member 90 (see Fig. 29) for adjusting the tilt of the lower stage 61 can be arranged between the lower base 61c and the lower laminate 61d. The lower base 61c and the lower laminate 61d are fixed together by, for example, a fastening member (not shown). Details of the tilt adjustment will be described later.

[0035] As shown in FIG. 7 , the lower reference marks MA2 are disposed on the lower stage 61. For example, four lower reference marks MA2 are disposed on the surface of the lower laminate 61d. The lower reference marks MA2 are formed on a transparent quartz plate member 61e. For example, two of the four lower reference marks MA2 are formed on one rectangular plate member 61e. The remaining two lower reference marks MA2 are each formed on one square plate member 61e. The four lower reference marks MA2 are disposed at the four corners of the square-shaped lower laminate 61d. Furthermore, as shown in FIG. 8 , the lower reference marks MA2 are formed, for example, by cross-shaped portions ma2.

[0036] 2, the alignment mark imaging unit 71 is configured to capture images of alignment marks (upper alignment mark AM1 and lower alignment mark AM2, which will be described later) arranged on the substrate W. The alignment mark imaging unit 71 is, for example, a microscope camera that captures images using visible light. The alignment mark imaging unit 71 also includes an upper alignment mark imaging unit 71a and a lower alignment mark imaging unit 71b.

[0037] The upper alignment mark imaging unit 71a is attached to the gate-shaped frame 63. The upper alignment mark imaging unit 71a is positioned so that its imaging direction faces the Z2 direction (downward). The upper alignment mark imaging unit 71a images the lower alignment mark AM2 (see FIG. 12) that is arranged on the second substrate W2 (lower substrate) held on the lower stage 61. The upper alignment mark imaging unit 71a also includes an upper wide-field alignment mark imaging unit 711a and an upper narrow-field alignment mark imaging unit 712a. While the upper narrow-field alignment mark imaging unit 712a has a narrower imaging range than the upper wide-field alignment mark imaging unit 711a, it is able to image the lower alignment mark AM2 with higher accuracy.

[0038] The lower alignment mark imaging unit 71b is attached to the Y-direction linear slider 62b of the XY stage 62. This allows the lower alignment mark imaging unit 71b to move in the Y direction together with the Y-direction linear slider 62b. The lower alignment mark imaging unit 71b is positioned so that its imaging direction faces the Z1 direction (upward). The lower alignment mark imaging unit 71b images the upper alignment mark AM1 (see FIG. 10) that is arranged on the first substrate W1 (upper substrate) held by the upper stage 51. The lower alignment mark imaging unit 71b also includes a lower wide-field alignment mark imaging unit 711b and a lower narrow-field alignment mark imaging unit 712b. The lower narrow-field alignment mark imaging section 712b has a narrower imaging range than the lower wide-field alignment mark imaging section 711b, but is capable of imaging the upper alignment mark AM1 with higher accuracy.

[0039] The reference mark imaging unit 72 images the upper reference mark MA1 and the lower reference mark MA2 from the vertical direction when the upper stage 51 and the lower stage 61 are positioned so that the upper reference mark MA1 and the lower reference mark MA2 overlap when viewed from the Z direction (vertical direction) (see FIG. 4). The reference mark imaging unit 72 is, for example, a visible light camera. The reference mark imaging unit 72 also has an autofocus function. The autofocus function is a function that automatically adjusts the focus to a subject.

[0040] A plurality of reference mark imaging units 72 are arranged. As shown in FIG. 9 , for example, three reference mark imaging units 72 are arranged. The three reference mark imaging units 72 are arranged on the back surface side (see FIG. 4 ) of the upper base portion 51 c of the upper stage 51. The back surface side of the upper base portion 51 c refers to the side opposite to the side on which the first substrate W1 (upper substrate) is held. The three reference mark imaging units 72 are arranged at three corners of the square-shaped upper base portion 51 c. As shown in FIG. 4 , the reference mark imaging units 72 are arranged so as to penetrate the upper base portion 51 c and the upper stack portion 51 d of the upper stage 51. The upper reference mark MA1 is arranged at the end where the reference mark imaging unit 72 penetrates the upper stack portion 51 d. This allows the reference mark imaging unit 72 to image the upper reference mark MA1. Furthermore, the three reference mark imaging units 72 each capture images of three of the four upper reference marks MA1.

[0041] 2, the inspection imaging unit 73 images the first substrate W1 (upper substrate) and the second substrate W2 (lower substrate) in a bonded state. The inspection imaging unit 73 is, for example, an infrared camera. The inspection imaging unit 73 is attached to the gate-shaped frame 63.

[0042] As shown in Fig. 2, the joining unit control unit 80 includes a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The joining unit control unit 80 controls the operation of the joining unit 5. The joining unit control unit 80 includes a storage unit 80a. The storage unit 80a is, for example, a flash memory, a solid state drive, or a hard disk. The storage unit 80a stores programs to be executed by the joining unit control unit 80.

[0043] (Substrate) The structure of the substrate W will be described.

[0044] As shown in FIG. 10 , the first substrate W1 (upper substrate) has a disk shape. A V-shaped notch N is formed in the first substrate W1. Note that an orientation flat may be formed instead of the notch N. The notch N and the orientation flat are intended to indicate the crystal orientation of the first substrate W1. An upper alignment mark AM1 is also arranged on the first substrate W1. For example, a plurality of upper alignment marks AM1 are arranged. FIG. 10 shows an example in which four upper alignment marks AM1 are arranged. As shown in FIG. 11 , the upper alignment mark AM1 is formed, for example, by a cross-shaped portion am1.

[0045] As shown in Figure 12, the second substrate W2 (lower substrate) has the same configuration as the first substrate W1. That is, the second substrate W2 has a disk shape. A V-shaped notch N is formed in the second substrate W2. Note that an orientation flat may be formed instead of the notch N. Also, a lower alignment mark AM2 is arranged on the second substrate W2. For example, a plurality of lower alignment marks AM2 are arranged. Figure 12 shows an example in which four lower alignment marks AM2 are arranged. Also, as shown in Figure 13, the lower alignment mark AM2 is composed of, for example, four L-shaped portions am2.

[0046] (Processing Flow of Substrate Bonding Apparatus) A schematic processing flow of the substrate bonding apparatus 1 will be described with reference to FIGS.

[0047] (Inversion Process) The first substrate W1 and the second substrate W2 are transported to the bonding unit 5 by an external transport robot. Here, the first substrate W1 (upper substrate) is held by the upper chuck 51a of the upper stage 51 facing upward. Meanwhile, the second substrate W2 (lower substrate) is held by the lower chuck 61a of the lower stage 61 facing upward. Here, the surfaces (bonding surfaces) of the first substrate W1 and the second substrate W2 may be hydrophilized in advance by plasma treatment, cleaning treatment, or the like. Thereafter, in step S1 of FIG. 14 , the upper stage 51 is rotated and inverted so that the upper chuck 51a faces downward.

[0048] 15, in step S2, the lower alignment mark AM2 of the second substrate W2 (lower substrate) held by the lower chuck 61a of the lower stage 61 is imaged by the upper alignment mark imaging unit 71a fixed to the frame 63. For example, the lower alignment mark AM2 is imaged by the upper wide-field alignment mark imaging unit 711a of the upper alignment mark imaging unit 71a to detect the rough position of the lower alignment mark AM2, and then the lower alignment mark AM2 is imaged by the upper narrow-field alignment mark imaging unit 712a to detect the position of the lower alignment mark AM2 with high accuracy. In addition, a plurality of lower alignment marks AM2 are arranged on the second substrate W2, and the upper alignment mark imaging unit 71a images the plurality of lower alignment marks AM2. Similarly, the upper alignment mark imaging unit 71a images the lower reference mark MA2 arranged on the lower stage 61. This allows the positions (coordinates) of the lower alignment mark AM2 and the lower reference mark MA2 to be detected.

[0049] 16 , the upper alignment mark AM1 of the first substrate W1 held by the upper chuck 51 a of the upper stage 51 is imaged by the lower alignment mark imaging unit 71 b fixed to the XY stage 62. A plurality of upper alignment marks AM1 are arranged on the first substrate W1, and the lower alignment mark imaging unit 71 b images the plurality of upper alignment marks AM1. Similarly, the upper reference mark MA1 arranged on the upper stage 51 is imaged by the lower alignment mark imaging unit 71 b. This allows the positions (coordinates) of the upper alignment mark AM1 and the upper reference mark MA1 to be detected.

[0050] 17, the first substrate W1 (upper substrate) and the second substrate W2 (lower substrate) are aligned so that they are positioned at a horizontal joining position based on the detected positions (coordinates) of the lower alignment mark AM2, lower reference mark MA2, upper alignment mark AM1, and upper reference mark MA1. Specifically, by operating the XY stage 62, the upper rotation motor 51b of the upper stage 51, and the lower rotation motor 61b of the lower stage 61, the first substrate W1 and the second substrate W2 are aligned so that the positional deviation between the first substrate W1 and the second substrate W2 at the horizontal joining position is minimized.

[0051] (Substrate Bonding Process) In step S4, the upper stage 51 is lowered to the Z2 side by driving the Z-direction linear motor 64a, as shown in Fig. 18. This bonds the first substrate W1 and the second substrate W2 together.

[0052] 19 , in step S5, the upper and lower reference marks MA1 and MA2, which overlap each other, are imaged by the inspection imaging section 73 fixed to the frame 63. The bonding unit control section 80 acquires the bonding accuracy of the first substrate W1 and the second substrate W2 based on the image acquired by the inspection imaging section 73. Then, based on the currently acquired bonding accuracy, the bonding unit control section 80 corrects the amount of movement when the first substrate W1 and the second substrate W2 are moved relative to each other in the next alignment process of the first substrate W1 and the second substrate W2.

[0053] (Method for Acquiring Stage Tilt State) Next, with reference to FIGS. 1 , 2 , 5 , 7 , 17 , and 20 to 28 , a method for acquiring the tilt state between the upper stage 51 and the lower stage 61 will be described in detail. After the alignment mark / reference mark detection process described above, in the alignment process, the first substrate W1 (upper substrate) and the second substrate W2 (lower substrate) are moved so that they face each other. At this time, the relative tilt relationship between the upper stage 51 and the lower stage 61 may be shifted as the first substrate W1 and the second substrate W2 move. Therefore, in this embodiment, information on the tilt between the upper stage 51 and the lower stage 61 is acquired when the first substrate W1 and the second substrate W2 face each other at the horizontal bonding position. Below, a method for acquiring the tilt state between the upper stage 51 and the lower stage 61 will be described in detail. The tilt state is acquired, for example, before the processes of the substrate bonding apparatus 1 from step S1 to step S5 are performed.

[0054] 20 , the upper stage 51 and the lower stage 61 are positioned so that, as viewed from the Z1 direction (vertical direction), an upper reference mark MA1 provided on the upper stage 51 holding the first substrate W1 and a lower reference mark MA2 provided on the lower stage 61 holding the second substrate W2 overlap. That is, similar to the alignment process shown in FIG. 17 , the upper stage 51 and the lower stage 61 are positioned so as to face each other at the joining position in the horizontal direction. Furthermore, the Z-direction linear motor 64 a is driven to lower the upper stage 51 to a predetermined position and bring it close to the lower stage 61. The predetermined position is, for example, a position that is set in advance based on design information so that both the upper reference mark MA1 and the lower reference mark MA2 are within the imaging focus (i.e., within the depth of field) of the reference mark imaging unit 72.

[0055] In step S12, the overlapping upper and lower reference marks MA1 and MA2 are imaged in the Z1 direction (vertical direction) by the reference mark imaging unit 72. For example, of the four upper and four lower reference marks MA1 and MA2, three upper and three lower reference marks MA1 and MA2 are imaged by the three reference mark imaging units 72. Hereinafter, an image captured by the reference mark imaging unit 72 in which the upper and lower reference marks MA1 and MA2 overlap is referred to as an overlap image G.

[0056] In step S13, the joining unit control unit 80 (see FIG. 1) acquires a pixel profile for the overlapping image G captured by the fiducial mark capturing unit 72. As shown in FIG. 21 , the pixel profile represents changes in luminance values ​​(graph) for the captured image, with the horizontal axis representing pixel coordinates and the vertical axis representing luminance values. For example, the overlapping image G captured by the fiducial mark capturing unit 72 is grayscaled. In the upper diagram of FIG. 21 , the upper and lower fiducial marks MA1 and MA2 are shown in white, and the surrounding areas are shown in black. The change in luminance values ​​when the grayscaled overlapping image G is scanned horizontally is plotted. The lower diagram of FIG. 21 shows the change in luminance values ​​when the grayscaled image is scanned in the direction indicated by the arrow. The pixel profile is acquired for all regions of the grayscaled image. Furthermore, a pixel profile is acquired for each of the three overlapping images G captured by the three fiducial mark capturing units 72.

[0057] In step S14, the joining unit control unit 80 (see FIG. 1) acquires a change in brightness value of an edge portion E of at least one of the upper and lower reference marks MA1 and MA2 in the overlapping image G. The edge portion E is the boundary between the upper and lower reference marks MA1 and MA2 and their surrounding areas in the overlapping image G. The joining unit control unit 80 differentiates the change in brightness value of the edge portion E to acquire a brightness gradient λ as the rate of change in brightness value. In this embodiment, the reference mark imaging unit 72 is attached to the upper stage 51, and the positional relationship between the reference mark imaging unit 72 and the upper stage 51 does not change, so the upper reference mark MA1 is always imaged in focus. Therefore, it is not necessary to acquire the brightness gradient λ of the edge portion E of the upper reference mark MA1.

[0058] In step S15, the joining unit control unit 80 determines whether the absolute value of the brightness gradient λ, which is the rate of change in brightness values, is equal to or less than a predetermined threshold λth. If the answer is No in step S15, the overlapping image G is considered to be in focus, and the tilt state between the upper stage 51 and the lower stage 61 is not acquired. If the absolute value of the brightness gradient λ, which is the rate of change in brightness values ​​of the edge portion E, is equal to or less than the threshold λth (if the answer is Yes in step S15), the joining unit control unit 80 executes control to acquire the tilt state between the upper stage 51 and the lower stage 61. That is, if the answer is Yes in step S15, the joining unit control unit 80 proceeds to step S16.

[0059] In step S16, in this embodiment, when the absolute value of the luminance gradient λ, which is the rate of change of the luminance value of the edge portion E, is equal to or less than the threshold value λth, the joining unit control unit 80 executes control to acquire the tilt state of the upper stage 51 and the lower stage 61. Specifically, the joining unit control unit 80 estimates, as the tilt state, the amount of vertical deviation d of at least one of the upper stage 51 and the lower stage 61 from a reference horizontal plane, based on a plurality of overlap images G previously acquired by being captured by the reference mark imaging unit 72 in an in-focus state and an out-of-focus state, and the overlap image G currently captured by the reference mark imaging unit 72. 22(a) when the upper reference mark MA1 and the lower reference mark MA2 are in focus (when the amount of deviation d of the upper stage 51 and the lower stage 61 is 0), as shown in FIG. 22(b) and FIG. 22(c) when the upper reference mark MA1 is in focus but the lower reference mark MA2 is out of focus (when the amount of deviation d of the lower stage 61 is xx μm and yy μm), as shown in FIG. 22(d) and FIG. 22(e) when the upper reference mark MA1 is out of focus but the lower reference mark MA2 is in focus (when the amount of deviation d of the upper stage 51 is xx μm and yy μm), and so on. Furthermore, the amount of deviation d in the vertical direction from the reference horizontal plane of the overlapping images G stored in the storage unit 80a is known. The storage unit 80a stores the overlapping image G and the amount of deviation d in association with each other.

[0060] The joining unit control unit 80 then performs pattern matching between the currently captured overlap image G and the overlap image G stored in the storage unit 80a. The joining unit control unit 80 estimates the amount of deviation d associated with the overlap image G with the highest degree of pattern matching (similarity) as the amount of deviation d of the currently captured overlap image G (the current upper stage 51 or lower stage 61). In Figure 22, the state in which the upper fiducial mark MA1 and the lower fiducial mark MA2 are in focus (clear and not blurred) is represented by no hatching, and the state in which the upper fiducial mark MA1 and the lower fiducial mark MA2 are out of focus (blurred) is represented by hatching. The more out of focus the images are, the greater the amount of deviation d.

[0061] As shown in Figure 23, when the upper stage 51 and the lower stage 61 are parallel to the reference horizontal plane, the edge portions E of the upper reference mark MA1 and the lower reference mark MA2 are clear and not blurred, as shown in Figure 22(a). As shown in Figure 24, when the lower stage 61 is tilted with respect to the reference horizontal plane and the upper stage 51 is parallel to the reference horizontal plane, the edge portion E of the upper reference mark MA1 is clear and not blurred, but the edge portion E of the lower reference mark MA2 is blurred, as shown in Figures 22(b) and 22(c). As shown in Figure 25, when the upper stage 51 is tilted with respect to the reference horizontal plane and the lower stage 61 is parallel to the reference horizontal plane, the edge portion E of the lower reference mark MA2 is clear and not blurred, but the edge portion E of the upper reference mark MA1 is blurred, as shown in Figures 22(d) and 22(e). 22 shows only five overlapping image G patterns, but in reality, many more overlapping images G are stored in the storage unit 80a. Furthermore, pattern matching of the overlapping images G is a process of determining the degree of match (similarity) between the current overlapping image G and the overlapping images G stored in the storage unit 80a. In this embodiment, the reference mark imaging unit 72 is attached to the upper stage 51, and the positional relationship between the reference mark imaging unit 72 and the upper stage 51 does not change. Therefore, the edge portion E of the upper reference mark MA1 is clear and not blurred, regardless of whether the upper stage 51 is tilted with respect to the reference horizontal plane. Therefore, there is no need to perform pattern matching with the overlapping images G, in which the edge portion of the upper reference mark MA1 is blurred.

[0062] Furthermore, in this embodiment, as described above, a plurality of (e.g., three) upper reference marks MA1 are arranged on the upper stage 51, and a plurality of (e.g., three) lower reference marks MA2 are arranged on the lower stage 61 so as to correspond to the plurality of upper reference marks MA1. The joining unit control unit 80 then acquires the tilt state based on the degree of focus of overlapping images G of multiple pairs of corresponding upper reference marks MA1 and lower reference marks MA2. That is, the joining unit control unit 80 estimates the vertical deviation amount d for each pair of corresponding upper reference marks MA1 and lower reference marks MA2. Here, the pair of upper reference marks MA1 and lower reference marks MA2 refers to the pair of upper reference marks MA1 and lower reference marks MA2 provided at corresponding positions on the upper stage 51 and lower stage 61. For example, the upper reference mark MA1 provided at the upper left corner of the upper stage 51 shown in FIG. 5 and the lower reference mark MA2 provided at the upper left corner of the lower stage 61 shown in FIG. 7 form a pair.

[0063] In step S17, in this embodiment, the bonding unit control unit 80 determines whether the vertical displacement d (absolute value) of at least one of the multiple pairs is equal to or greater than the displacement threshold dth. If the displacement d (absolute value) is equal to or greater than the displacement threshold dth, in step S18, the bonding unit control unit 80 causes the display unit 31a (see FIG. 1) to display a message urging the maintenance worker to adjust at least one of the upper stage 51 and the lower stage 61, as shown in FIG. 26. For example, the display unit 31a displays a message stating, "A malfunction in the bonding unit has been detected. Please contact our service department."

[0064] In step S19, in this embodiment, the bonding unit control unit 80 displays a message on the portable display unit 31b (see FIG. 1 ) such as a tablet terminal, urging the maintenance worker to perform an inclination adjustment operation (parallel adjustment operation) to adjust at least one of the upper stage 51 and the lower stage 61 from an inclined state to a horizontal state (parallel state). For example, as shown in FIG. 27 , a message saying "Please check the maintenance screen and perform the stage parallel adjustment of the bonding unit" is displayed on the display unit 31b.

[0065] In this embodiment, when the vertical displacement d (absolute value) of at least one of the plurality of pairs is equal to or greater than the displacement threshold dth, the joining unit control unit 80 controls the display unit 31b to display each of the plurality of pairs of overlapping images G and the vertical displacement d for each of the plurality of pairs. For example, as shown in FIG. 27 , each of three pairs of overlapping images G and their respective displacements d are displayed on the display unit 31b. In FIG. 27 , the displacement d1 of the first pair of overlapping images G is +3 μm, the displacement d2 of the second pair of overlapping images G is −10 μm, and the displacement d3 of the third pair of overlapping images G is −15 μm.

[0066] In this embodiment, the joining unit control unit 80 also displays information on whether the vertical displacement d (absolute value) is equal to or greater than the displacement threshold dth on the display unit 31b, along with the vertical displacement d. For example, as shown in FIG. 27 , the display unit 31b indicates that the displacement d of the overlapping image G is within the displacement threshold dth, indicating "OK." Furthermore, the display unit 31b indicates that the displacement d of each of the three sets of overlapping images G exceeds the displacement threshold dth, indicating "NG." The displacement threshold dth is, for example, 4 μm. Furthermore, the display unit 31b displays simulated images of the upper stage 51 and the lower stage 61, corresponding to the inclination of each stage. The display unit 31b also displays the displacements d1, d2, and d3 of each of the three sets of overlapping images G relative to the reference horizontal plane.

[0067] Also, if the answer is No in step S17, as shown in FIG. 28, three sets of overlapping images G and simulated images of the upper stage 51 and lower stage 61 that are horizontal to each other are displayed on the display unit 31b.

[0068] (Tilt Adjustment Work by Maintenance Worker) Next, with reference to FIG. 29 , tilt adjustment work by a maintenance worker will be described. As described above, based on the message displayed on the display unit 31a (see FIG. 26 ) prompting the user to request a maintenance worker to adjust at least one of the upper stage 51 and the lower stage 61, the user requests a maintenance worker to adjust the tilt. The maintenance worker places an adjustment sheet member 90 based on the vertical deviation amount d of multiple pairs of upper reference marks MA1 and lower reference marks MA2 displayed on the display unit 31b (see FIG. 27 ). For example, as shown in FIG. 29 , if the lower stage 61 is tilted, the adjustment sheet member 90 is placed between the lower base portion 61c and the lower stack portion 61d of the lower stage 61. This adjusts the relative tilt of the lower stack portion 61d of the lower stage 61 with respect to the upper stage 51, so that the first substrate W1 held by the upper stage 51 and the second substrate W2 held by the lower stage 61 become parallel. The adjustment sheet member 90 is made of, for example, carbon steel or stainless steel, etc. Furthermore, adjustment sheet members 90 are available in various thicknesses ranging from several μm to several hundred μm, and the thickness of the adjustment sheet member 90 used in the tilt adjustment work is selected depending on the degree of tilt adjustment.

[0069] [Effects of this embodiment] In this embodiment, the following effects can be obtained.

[0070] In the present embodiment, as described above, the bonding unit control unit 80 acquires the tilt state of at least one of the upper stage 51 and the lower stage 61 based on the degree of focus of the overlap image G, which is an image of the upper reference mark MA1 and the lower reference mark MA2 overlapped and captured by the reference mark imaging unit 72. In this manner, it is possible to acquire information about the tilt of the upper stage 51 and the lower stage 61 as described above when the upper stage 51 and the lower stage 61 are facing each other at the horizontal bonding position. Therefore, unlike when information about the tilt of the upper stage 51 and the lower stage 61 is acquired at a position other than the position where the upper stage 51 and the lower stage 61 are facing each other, it is possible to acquire the tilt state of the upper stage 51 and the lower stage 61 in a state close to when the first substrate W1 and the second substrate W2 are at the horizontal bonding position. As a result, it is possible to more accurately acquire information about the tilt of the upper stage 51 and the lower stage 61 when the first substrate W1 and the second substrate W2 are at the horizontal bonding position.

[0071] In this embodiment, as described above, multiple upper reference marks MA1 and multiple lower reference marks MA2 are arranged, so it is possible to acquire the tilt state at multiple locations on the upper stage 51 and the lower stage 61. As a result, it is also possible to obtain information on the direction in which the entire upper stage 51 and the lower stage 61 are tilted, based on the tilt state at multiple locations.

[0072] In this embodiment, as described above, the joining unit control unit 80 executes control to acquire the tilt state when the rate of change in the brightness value of the edge portion E (brightness gradient λ) is equal to or less than the change rate threshold (λth). Here, when the rate of change in the brightness value of the edge portion E is equal to or less than the change rate threshold, the overlap image G is relatively out of focus. On the other hand, when the rate of change in the brightness value of the edge portion E exceeds the change rate threshold, the overlap image G is relatively in focus. Therefore, when the rate of change in the brightness value of the edge portion E exceeds the change rate threshold, tilt adjustment is not necessary. Therefore, by not executing control to acquire the tilt state by the joining unit control unit 80, the control burden on the joining unit control unit 80 can be reduced.

[0073] In this embodiment, as described above, the joining unit control unit 80 performs pattern matching between a plurality of overlapping images G acquired in advance and the overlapping image G captured currently, and estimates the amount of vertical deviation d of at least one of the upper stage 51 and the lower stage 61 from the reference horizontal plane based on the pattern-matched image. As a result, it is possible to estimate the amount of vertical deviation d of at least one of the upper stage 51 and the lower stage 61 without providing a separate sensor for detecting tilt, etc.

[0074] In this embodiment, as described above, multiple upper reference marks MA1 and multiple lower reference marks MA2 are arranged, so that the vertical deviation amount d can be obtained at multiple locations on the upper stage 51 and the lower stage 61. As a result, a maintenance worker or the like who performs the tilt adjustment can easily determine how much tilt adjustment is required at each of the multiple locations on the upper stage 51 and the lower stage 61.

[0075] In this embodiment, as described above, when it is necessary to adjust the tilt of at least one of the upper stage 51 and the lower stage 61, a message is displayed on the display unit 31a urging the user to request a maintenance worker to do so. Therefore, by looking at the display unit 31a, the user can easily recognize that it is necessary to adjust the tilt of the substrate bonding apparatus 1.

[0076] In this embodiment, as described above, when the vertical deviation d of at least one of the plurality of pairs is equal to or greater than the deviation threshold dth, the bonding unit control unit 80 causes the display unit 31b to display a message urging the maintenance worker to perform tilt adjustment work to adjust at least one of the upper stage 51 and the lower stage 61 from an inclined state to a horizontal state. This allows the maintenance worker to easily recognize that tilt adjustment is necessary.

[0077] In this embodiment, as described above, when the vertical displacement d of at least one of the plurality of pairs is equal to or greater than the displacement threshold dth, the bonding unit control unit 80 causes the display unit 31b to display the vertical displacement d of each of the plurality of pairs. This makes it easy to know at which location on at least one of the upper stage 51 and the lower stage 61 the tilt adjustment should be performed and to what extent, and allows the tilt adjustment work to be performed efficiently.

[0078] In this embodiment, as described above, the joining unit control unit 80 causes the display unit 31b to display information on whether the vertical deviation d for each of the plurality of pairs is equal to or greater than the deviation threshold dth. This allows the maintenance worker to easily identify the locations that require tilt adjustment by visually checking the display unit 31b, thereby enabling the tilt adjustment work to be performed more efficiently.

[0079] As described above, in this embodiment, an adjustment sheet member 90 for adjusting the tilt of the upper stage 51 is configured to be able to be arranged between the upper base portion 51c and the upper stack portion 51d. Similarly, an adjustment sheet member 90 for adjusting the tilt of the lower stage 61 is configured to be able to be arranged between the lower base portion 61c and the lower stack portion 61d. This makes it possible to easily adjust the tilt of at least one of the upper stage 51 and the lower stage 61 simply by arranging the adjustment sheet member 90 between the upper base portion 51c (61c) and the upper stack portion 51d (61d).

[0080] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0081] In the above embodiment, an example was shown in which a plurality (four) of upper reference marks MA1 were arranged on the upper stage 51 and a plurality (four) of lower reference marks MA2 were arranged on the lower stage 61 so as to correspond to the plurality of upper reference marks MA1, but the present invention is not limited to this. For example, one upper reference mark MA1 and one lower reference mark MA2 may be arranged. Furthermore, a plurality of three or more upper reference marks MA1 and three or more lower reference marks MA2 may be arranged.

[0082] Furthermore, in the above embodiment, an example was shown in which the reference mark imaging unit 72 was disposed on the upper stage 51 and the upper reference mark MA1 disposed on the upper stage 51 was always imaged in focus, but the present invention is not limited to this. For example, the reference mark imaging unit 72 may be disposed at a position separated from the upper stage 51 and the lower stage 61. In this case, since the upper reference mark MA1 disposed on the upper stage 51 is not always imaged in focus, it is necessary to obtain the tilt state based on changes in the brightness values ​​of the edge portions E of both the upper reference mark MA1 and the lower reference mark MA2 in the overlap image G.

[0083] In the above embodiment, an example was shown in which the luminance gradient λ was used as the rate of change of the luminance value of the edge portion E, but the present invention is not limited to this. For example, an index other than the luminance gradient λ may be used as the rate of change of the luminance value of the edge portion E. Furthermore, the state of the slope may be acquired based on the amount of change in the luminance value, rather than the rate of change in the luminance value.

[0084] In the above embodiment, the joining unit control unit 80 estimates the vertical displacement d based on pattern matching between the overlapping image G captured in the current image and multiple overlapping images G previously captured by the reference mark image capturing unit 72 in an in-focus state and an out-of-focus state. However, the present invention is not limited to this. For example, the joining unit control unit 80 may estimate the vertical displacement d of the currently captured overlapping image G using a learning model previously trained by machine learning. Furthermore, the joining unit control unit 80 may estimate the vertical displacement d based on an index indicating matching other than pattern matching. Alternatively, the joining unit control unit 80 may estimate the vertical displacement d based on a change in the brightness value of the edge portion E.

[0085] In the above embodiment, the joining unit control unit 80 estimates the vertical displacement amount d for each pair of corresponding upper and lower reference marks MA1 and MA2, but the present invention is not limited to this. For example, the joining unit control unit 80 may learn multiple pairs of overlapping images G in advance through machine learning and use the learned model to collectively estimate the displacement amounts d for multiple pairs of overlapping images G.

[0086] In the above embodiment, an example is shown in which the display unit 31 a displays (notifies) a message prompting the maintenance worker to adjust at least one of the upper stage 51 and the lower stage 61. However, the present invention is not limited to this. For example, the bonding unit control unit 80 may notify the user by sound or light that at least one of the upper stage 51 and the lower stage 61 needs to be adjusted. Furthermore, the above message may be displayed on a display unit (not shown) provided in the bonding unit 5 that is provided separately from the display unit 31 a of the substrate bonding apparatus 1.

[0087] In the above embodiment, an example is shown in which a message urging the maintenance worker to perform the tilt adjustment work is displayed on the display unit 31, but the present invention is not limited to this. For example, the maintenance worker may be notified by sending a message urging the maintenance worker to perform the tilt adjustment work by email or the like to a mobile terminal or PC of the maintenance worker.

[0088] In the above embodiment, the joining unit control unit 80 displays the overlapping image G of each of the plurality of pairs and the vertical displacement amount d for each of the plurality of pairs on the display unit 31b, but the present invention is not limited to this. For example, the joining unit control unit 80 may display only the vertical displacement amount d for each of the plurality of pairs on the display unit 31b without displaying the overlapping image G.

[0089] In the above embodiment, the joining unit control unit 80 displays information (OK or NG) about whether the vertical deviation amount d is equal to or greater than the deviation amount threshold dth on the display unit 31a together with the vertical deviation amount d, but the present invention is not limited to this. For example, the maintenance worker may determine whether tilt adjustment work is necessary based on the deviation amount d without displaying information about whether the vertical deviation amount d is equal to or greater than the deviation amount threshold dth on the display unit.

[0090] Furthermore, in the above embodiment, the tilt state is acquired before the processes of the substrate bonding apparatus 1 (bonding unit 5) in steps S1 to S5 are performed. However, the present invention is not limited to this. For example, in step S4 of FIG. 14 , the tilt state may be acquired before or during the upper stage 51 descends toward the Z2 side. Here, if the bonding unit control unit 80 detects that the deviation amount d is equal to or greater than the deviation amount threshold dth, the bonding operation of the first substrate W1 and the second substrate W2 may be stopped. In this way, if the deviation amount d of at least one pair is equal to or greater than the deviation amount threshold dth during operation of the substrate bonding apparatus 1, the bonding operation is automatically stopped by the bonding unit control unit 80. This prevents the bonding operation from being continued in a state where the upper stage 51 and the lower stage 61 are not parallel to each other.

[0091] Furthermore, in the above embodiment, an example was shown in which the maintenance worker adjusted the tilt of the lower stage 61 by placing the adjustment sheet member 90 between the lower base portion 61c and the lower stack portion 61d of the lower stage 61, but the present invention is not limited to this. For example, a spherical pedestal may be placed below the lower stage 61, and the bonding unit control unit 80 may drive the spherical pedestal to automatically adjust the tilt of the lower stage 61. Note that when the bonding unit control unit 80 performs automatic tilt adjustment, it is preferable to adjust the tilt of the first substrate W1 and the second substrate W2 for each bonding process.

[0092] DESCRIPTION OF SYMBOLS 1 Substrate bonding apparatus 31a Display unit 31b Display unit 51 Upper stage (first stage) 51c Upper base unit (base unit) 51d Upper stacking unit (stacking unit) 61 Lower stage (second stage) 61c Lower base unit (base unit) 61d Lower stacking unit (stacking unit) 72 Reference mark imaging unit 80 Bonding unit control unit (control unit) 90 Adjustment sheet member d Misalignment amount G Overlap image W1 First substrate (upper substrate) W2 Second substrate (lower substrate) MA1 Upper reference mark (first reference mark) MA2 Lower reference mark (second reference mark)

Claims

1. A substrate bonding device comprising: a first stage capable of holding a first substrate and on which a first reference mark is arranged; a second stage capable of holding a second substrate and on which a second reference mark is arranged; a reference mark imaging unit that images the first reference mark and the second reference mark from the vertical direction while the first stage and the second stage are arranged so that the first reference mark and the second reference mark overlap when viewed from the vertical direction; and a control unit that obtains the tilt state of at least one of the first stage and the second stage based on the degree of focus of an overlapping image, which is an image of the overlapping first reference mark and the second reference mark captured by the reference mark imaging unit.

2. The substrate bonding apparatus of claim 1, wherein a plurality of the first reference marks are arranged on the first stage, a plurality of the second reference marks are arranged on the second stage so as to correspond to the plurality of first reference marks, and the control unit acquires the tilt state based on the degree of focus of the overlapping images of the plurality of sets of the corresponding first reference marks and the second reference marks.

3. The substrate bonding apparatus of claim 1, wherein the control unit executes control to acquire the tilt state based on changes in the brightness value of the edge portion of at least one of the first reference mark and the second reference mark in the overlapping image.

4. The substrate bonding apparatus of claim 1, wherein the control unit estimates the amount of vertical deviation of at least one of the first stage and the second stage from a reference horizontal plane as the tilt state based on multiple overlapping images previously captured by the reference mark imaging unit in in-focus and out-of-focus states and the overlapping image currently captured by the reference mark imaging unit.

5. A substrate bonding apparatus as described in claim 4, wherein a plurality of the first reference marks are arranged on the first stage, a plurality of the second reference marks are arranged on the second stage so as to correspond to the plurality of first reference marks, and the control unit estimates the amount of deviation in the vertical direction for each pair of the first reference mark and the second reference mark that correspond to each other.

6. The substrate bonding apparatus of claim 5, wherein the control unit causes a display unit to display a message prompting adjustment of at least one of the first stage and the second stage when the vertical deviation of at least one of the plurality of groups is equal to or greater than a deviation threshold.

7. A substrate bonding apparatus as described in claim 5, wherein the control unit causes a display unit to display information regarding the amount of vertical deviation for each of the plurality of groups when the amount of vertical deviation for at least one of the plurality of groups is equal to or greater than a deviation threshold.

8. The substrate bonding apparatus of claim 5, wherein the control unit stops the bonding operation of the first substrate and the second substrate when the amount of deviation of at least one of the plurality of pairs is equal to or greater than a deviation amount threshold.

9. A substrate bonding device as described in claim 1, wherein at least one of the first stage and the second stage includes a base portion and a stack portion stacked on the base portion, and an adjustment sheet member for adjusting the inclination of at least one of the first stage and the second stage can be arranged between the base portion and the stack portion.

10. A substrate bonding method comprising the steps of: positioning a first stage and a second stage so that a first reference mark provided on a first stage capable of holding a first substrate and a second reference mark provided on a second stage capable of holding a second substrate overlap when viewed from the vertical direction; capturing an image of the overlapping first reference mark and second reference mark from the vertical direction; and acquiring the tilt state of at least one of the first stage and the second stage based on the degree of focus of an overlapping image, which is an image in which the captured first reference mark and second reference mark overlap.

Images