Wafer bonding equipment

Abstract

This invention provides a wafer bonding apparatus that enables in-situ measurement and evaluation of wafer bonding. [Solution] The wafer bonding apparatus 1 includes a bonding section 10 that bonds the first wafer and the second wafer by adsorbing and holding the first wafer W1 and the second wafer W2 with a first chuck 110 and a second chuck 120, and bringing the first wafer and the second wafer into contact with each other while at least one of the first wafer and the second wafer is bent; a light source 50 positioned to the side of the first chuck and the second chuck and irradiating light into the region between the first chuck and the second chuck; a plurality of cameras 60 positioned on the opposite side of the light source with the first chuck and the second chuck in between and imaging the region where light is irradiated; and a generation section that generates three-dimensional image data showing the bonding scene of the first wafer and the second wafer by three-dimensionally reconstructing image data obtained by imaging the region with the plurality of cameras during the bonding of the first wafer and the second wafer.

Description

Technical Field

[0001] The present invention relates to a wafer bonding apparatus.

Background Art

[0002] Wafer bonding technology is a very important technology for realizing three-dimensional mounting of semiconductor devices.

[0003] Bonding of two wafers is performed by bringing the wafers into contact with each other in a state where the wafers are warped by pressing the central portion of the wafer from the back side to suppress the generation of voids between the wafers (for example, Patent Document 1). Regarding the presence or absence of voids between the bonded wafers, inspection is performed using an IR camera or the like in an inspection apparatus (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, inspection using an IR camera or the like in an inspection apparatus has a problem that it takes time to feedback the inspection result because it is necessary to move the wafer from the wafer bonding apparatus to the inspection apparatus. Therefore, development of a technology for measuring and evaluating wafer bonding in-situ is desired.

[0006] [[ID=4I]]The present invention has been made in view of the above problems. Therefore, an object of the present invention is to provide a wafer bonding apparatus that enables in-situ measurement and evaluation of wafer bonding.

Means for Solving the Problems

[0007] The above objectives of the present invention are achieved by the following means.

[0008] (1) A wafer bonding apparatus comprising: a bonding section that joins a first wafer and a second wafer by adsorbing and holding the first wafer and the second wafer with a first chuck and a second chuck arranged opposite each other, and bringing the first wafer and the second wafer into contact with each other while bending at least one of the first wafer and the second wafer so that the central portions of the first wafer and the second wafer are close together; a light source arranged to the side of the first chuck and the second chuck and irradiating light into the region between the first chuck and the second chuck; a plurality of cameras arranged on opposite sides of the light source with the first chuck and the second chuck in between, and each imaging the region irradiated by light from the light source; and a generation unit that generates three-dimensional image data showing the bonding scene of the first wafer and the second wafer by three-dimensionally reconstructing image data obtained by imaging the region with the plurality of cameras during the bonding of the first wafer and the second wafer.

[0009] (2) The wafer bonding apparatus according to (1), wherein each camera continuously images the region at a predetermined imaging period, and the generation unit generates a plurality of three-dimensional image data showing the behavior of the first wafer and the second wafer during the bonding process of the first wafer and the second wafer based on image data that is continuous at predetermined time intervals.

[0010] (3) The wafer bonding apparatus according to (1) or (2) above, wherein the number of cameras is greater than the number of light sources.

[0011] (4) The wafer bonding apparatus according to (1) or (2) above, further comprising: a first drive unit for bringing the first chuck and the second chuck closer together and further apart; and a first control unit for adjusting the distance between the first wafer and the second wafer by controlling the first drive unit based on image data obtained by imaging the region with the camera.

[0012] (5) The wafer bonding apparatus according to (1) or (2) above, further comprising: a second drive unit for changing the inclination of at least one of the first chuck and the second chuck; and a second control unit for adjusting the inclination of at least one of the first wafer and the second wafer by controlling the second drive unit based on image data obtained by imaging the region with the camera.

[0013] (6) The wafer bonding apparatus according to (1) or (2) above, further comprising: an adjustment unit for adjusting the suction holding force of at least one of the first chuck and the second chuck; and a third control unit for adjusting the warpage of at least one of the first wafer and the second wafer by controlling the adjustment unit based on image data obtained by imaging the region with the camera.

[0014] (7) The wafer bonding apparatus according to (1) or (2) above, further comprising a third drive unit for moving the light source and the camera between a measurement position in which the light source and the camera are located around the first chuck and the second chuck, and a retracted position in which the light source and the camera are located away from the measurement position.

[0015] (8) The wafer bonding apparatus according to (1) or (2) above, wherein the light source is configured to irradiate P-polarized or S-polarized light.

[0016] (9) The wafer bonding apparatus according to (1) or (2) above, wherein the light source is configured to be adjustable in at least one of the angle of light spread and the amount of light.

[0017] (10) The light source is a laser light source with a central wavelength within the range of 200 nm or more and 800 nm or less, and the wafer bonding apparatus according to (1) or (2) above.

[0018] (11) The wafer bonding apparatus according to (1) or (2) above further includes an infrared camera that images the alignment marks of the first wafer and the second wafer.

[0019] (12) The wafer bonding apparatus according to (1) or (2) above further includes a distance sensor that detects the distance between the first chuck and the second chuck.

[0020] (13) The wafer bonding apparatus according to (1) or (2) above further includes a plasma irradiation unit that is provided separately from the bonding portion and irradiates the first wafer and the second wafer with plasma before being adsorbed and held by the first chuck and the second chuck.

Advantages of the Invention

[0021] According to the present invention, it becomes possible to measure and evaluate the bonding of wafers in situ.

Brief Description of the Drawings

[0022] [Figure 1] It is a block diagram showing a schematic configuration of a wafer bonding apparatus. [Figure 2] It is a diagram showing a schematic configuration of a bonding portion and a measurement portion. [Figure 3] It is a plan view showing a schematic configuration of a measurement portion. [Figure 4] It is a flowchart showing a procedure of a wafer bonding process. [Figure 5A] It is a diagram showing an example of a wafer bonding scene. [Figure 5B] It is a figure following FIG. 5A. [Figure 5C] It is a figure following FIG. 5B. [Figure 5D] It is a figure following FIG. 5C. [Figure 5E]This figure follows Figure 5D. [Figure 6] This figure shows an example of an captured image. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings is exaggerated for clarity and convenience of explanation. On the other hand, the embodiments described below are merely illustrative, and various modifications are possible from such embodiments.

[0024] In the following, "upper part" or "top" may include not only items that are directly above and in contact, but also items that are above but not in contact. Similarly, "lower part" or "bottom" may include not only items that are directly below and in contact, but also items that are below but not in contact.

[0025] A singular expression includes plural expressions unless the context clearly indicates that it is singular. Furthermore, when a part "includes," "companies," or "has" a component, it does not exclude other components, but rather may include other components, unless otherwise specified.

[0026] Unless explicitly stated otherwise, the steps constituting the method shall be performed in the appropriate order. This order is not necessarily limited to the order in which the steps are described. The use of any examples or illustrative terms is solely for the purpose of illustrating a technical idea and is not limited by the scope of the claims.

[0027] In the following explanations, when ordinal numbers such as "1st" and "2nd" are used, they are for convenience only and do not prescribe any particular order unless otherwise specified.

[0028] A wafer bonding apparatus according to one embodiment of the present invention will be described below with reference to Figures 1 to 6.

[0029] Figure 1 is a block diagram showing the schematic configuration of the wafer bonding apparatus 1 according to this embodiment. As shown in Figure 1, the wafer bonding apparatus 1 comprises a bonding unit 10, a measurement unit 20, a plasma irradiation unit 30, and a control unit 40.

[0030] The bonding section 10 joins two wafers. The bonding section 10 is connected to an external vacuum pump via an adjustment valve 15, and joins the two wafers while holding them by suction. The bonding section 10 joins the two wafers by bending each wafer so that their centers are close together, and then bringing the two wafers into contact.

[0031] The measurement unit 20 measures the bonding process of two wafers. The measurement unit 20 has a light source 50 and a camera 60, and while irradiating the boundary region of the two wafers being bonded with light, it images the boundary region.

[0032] The plasma irradiation unit 30 irradiates two wafers with plasma to activate the bonding surface of each wafer. The wafers irradiated with plasma by the plasma irradiation unit 30 are transported to the bonding unit 10 by a transport robot (not shown).

[0033] The control unit 40 controls each of the above-mentioned parts and performs various calculations. The control unit 40 is composed of a computer and includes a CPU, memory (ROM, RAM), storage unit (HDD, SSD), display, and input unit (keyboard, etc.).

[0034] The memory unit of the control unit 40 stores programs for controlling the operation of each of the above-mentioned parts, a program for 3D reconstruction of image data obtained by imaging the boundary region of two wafers with the camera 60, and a program (learning model) for determining the quality of the bonding of the two wafers. In this embodiment, the control unit 40 functions as a generation unit that generates 3D image data by reconstructing 2D image data into 3D data through the execution of a program for 3D reconstruction of image data by the CPU. Note that 3D reconstruction refers to a technique for restoring a 3D model (3D image data) of a scene from 2D image data obtained by imaging the scene from multiple viewpoints.

[0035] The wafer bonding apparatus 1 may also include components other than those described above, and may not include some of the components described above. For example, the control unit 40 may further include a GPU (Graphics Processing Unit) for performing 3D reconstruction of image data. Alternatively, the wafer bonding apparatus 1 may include a computer separate from the control unit 40 for performing 3D reconstruction of image data and determining the quality of wafer bonding.

[0036] Next, the joint 10 and the measuring section 20 will be described in more detail with reference to Figures 2 and 3. Figure 2 is a diagram showing the schematic configuration of the joint 10 and the measuring section 20, and Figure 3 is a plan view showing the schematic configuration of the measuring section 20.

[0037] <Joint part 10> The joint 10 includes first and second chucks 110 and 120 arranged facing each other, and a drive unit 130 for changing the position and orientation of the first and second chucks 110 and 120.

[0038] The first and second chucks 110 and 120 hold the first and second wafers W1 and W2 by suction. The first and second chucks 110 and 120 are made of, for example, ceramics, and hold the first and second wafers W1 and W2 by suction applied to suction grooves (not shown) formed on the wafer holding surface. The suction grooves are independently provided for each divided region obtained by dividing the wafer holding surface of the first and second chucks 110 and 120 into multiple sections, and the wafer bonding apparatus 1 can adjust the suction holding force of the wafer holding surface of the first and second chucks 110 and 120 on a divided region basis.

[0039] The first and second chucks 110 and 120 are provided with first and second pressing members 111 and 121 for pressing the first and second wafers W1 and W2. The first and second pressing members 111 and 121 press the central portions of the first and second wafers W1 and W2 from the back side through openings provided in the first and second chucks 110 and 120. The tips of the first and second pressing members 111 and 121 are provided with load sensors (not shown) for detecting contact with the first and second wafers W1 and W2.

[0040] Furthermore, the first chuck 110 is equipped with multiple infrared cameras 112 and multiple distance sensors 113. The infrared cameras 112 are, for example, InGaAs cameras and are configured to be movable in the vertical and horizontal directions by a drive mechanism (not shown). The infrared cameras 112 capture alignment marks on the first and second wafers W1 and W2 while irradiating them with infrared light from an infrared light source (not shown). The distance sensors 113 are, for example, capacitance sensors and detect the distance between the wafer holding surface of the first chuck 110 and the wafer holding surface of the second chuck 120. The distance sensors 113 are provided at a position on the periphery of the first chuck 110 that does not overlap with the first wafer W1.

[0041] Furthermore, multiple alignment marks 114 and 124 are provided on the sides of the first and second chucks 110 and 120, respectively, for positioning the camera 60. The alignment marks 114 and 124 are provided at predetermined positions on the sides of the first and second chucks 110 and 120 so as to fit within the field of view (imaging range) of the camera 60.

[0042] The drive unit 130 includes an XY stage 131, a Z stage 132, a theta stage 133, and a tilt stage 134. The XY stage 131 changes the horizontal position (in the X-axis and Y-axis directions) of the second chuck 120 relative to the first chuck 110. The Z stage 132 changes the vertical position (in the Z-axis direction) of the second chuck 120 relative to the first chuck 110. The theta stage 133 adjusts the inclination of the second chuck 120 in the horizontal plane (around the Z-axis) relative to the first chuck 110. The tilt stage 134 adjusts the vertical inclination (around the X-axis and Y-axis) of the second chuck 120 relative to the first chuck 110.

[0043] <Measurement unit 20> The measurement unit 20 includes first and second light sources 50a and 50b, and first to eighth cameras 60a to 60h. The first and second light sources 50a and 50b and the first to eighth cameras 60a to 60h are arranged on an annular member 71 that surrounds the first and second chucks 110 and 120. The annular member 71 is configured to be movable in the vertical direction (Z-axis direction) by a drive unit 72. The drive unit 72 moves the light sources 50a and 50b and cameras 60a to 60h between a measurement position where the light sources 50a and 50b and cameras 60a to 60h are located around the first and second chucks 110 and 120, and a retracted position where the light sources 50a and 50b and cameras 60a to 60h are located below the first and second chucks 110 and 120.

[0044] The first and second light sources 50a and 50b are positioned to the sides of the first and second chucks 110 and 120, and irradiate light into the area between the first and second chucks 110 and 120. The first and second light sources 50a and 50b are, for example, laser light sources that emit blue light, and irradiate slit light having a predetermined divergence angle in the horizontal direction parallel to the wafer holding surfaces of the first and second chucks 110 and 120. From the standpoint of suppressing the output of the light source 50, it is preferable that the slit width (vertical height) of the slit light be set to a value less than or equal to the distance between the first and second wafers W1 and W2 held by the first and second chucks 110 and 120 (approximately 10 μm to 100 μm).

[0045] Furthermore, the first and second light sources 50a and 50b emit linearly polarized light (P-polarized or S-polarized). The first and second light sources 50a and 50b are equipped with various filters 51, such as a polarizing filter that can switch between P-polarized and S-polarized light, an ND filter that can adjust the light intensity, and a spatial filter that can adjust the light divergence angle. These parameters are set appropriately according to the Brewster angle and scattering characteristics of the wafer surfaces W1 and W2.

[0046] The first to eighth cameras 60a to 60h are positioned on the opposite side of the first and second light sources 50a and 50b, with the first and second chucks 110 and 120 in between, and image the area illuminated by the first and second light sources 50a and 50b. The first to eighth cameras 60a to 60h are positioned at regular angular intervals so as to surround half (180 degrees) of the first and second chucks 110 and 120. The first to eighth cameras 60a to 60h are, for example, image sensors such as CCD or CMOS, and image the above area at a predetermined imaging period (for example, 1 kHz).

[0047] The configuration of the joint 10 and the measurement unit 20 is not limited to the above configuration. For example, the measurement unit 20 may be equipped with nine or more or seven or fewer cameras 60. Alternatively, the measurement unit 20 may be equipped with a single light source 50.

[0048] With the wafer bonding apparatus 1 configured as described above, the bonding of the first and second wafers W1 and W2 is measured and evaluated in situ. More specifically, the bonding process of the first and second wafers W1 and W2 is captured by multiple cameras 60, and the bonding scene of the first and second wafers W1 and W2 is restored as a three-dimensional model (three-dimensional image data) by three-dimensional reconstruction of the obtained image data. Then, the quality of the bonding of the first and second wafers W1 and W2 is determined based on the three-dimensional image data of the bonding scene of the first and second wafers W1 and W2. The operation of the wafer bonding apparatus 1 will be described below with reference to Figures 4 to 6.

[0049] Figure 4 is a flowchart showing the procedure for the wafer bonding process performed by the wafer bonding apparatus 1. The process shown in the flowchart in Figure 4 is realized by the control unit 40 controlling the operation of each part of the wafer bonding apparatus 1 according to the program, or by the control unit 40 performing various calculation processes.

[0050] (Step S101) First, the wafer bonding apparatus 1 uses first and second chucks 110 and 120 to hold the first and second wafers W1 and W2 by suction. More specifically, the wafer bonding apparatus 1 irradiates the first and second wafers W1 and W2 with plasma using a plasma irradiation unit 30, and then uses a transport robot (not shown) to transport the first and second wafers W1 and W2 to the vicinity of the first and second chucks 110 and 120. Then, the wafer bonding apparatus 1 generates negative pressure on the wafer holding surfaces of the first and second chucks 110 and 120 to hold the first and second wafers W1 and W2 by suction.

[0051] While the first and second wafers W1 and W2 are being transported from the plasma irradiation unit 30 to the bonding unit 10, the light source 50 and camera 60 wait in a retracted position below the first and second chucks 110 and 120. Then, once the first and second wafers W1 and W2 are held by the first and second chucks 110 and 120, the light source 50 and camera 60 move from the retracted position below the first and second chucks 110 and 120 to a measurement position around the first and second chucks 110 and 120.

[0052] (Step S102) Next, the wafer bonding apparatus 1 adjusts the position and orientation of the first and second chucks 110 and 120. More specifically, the wafer bonding apparatus 1 first detects the distance between the first and second chucks 110 and 120 using a plurality of distance sensors 113. Then, based on the output of the plurality of distance sensors 113, the wafer bonding apparatus 1 controls the Z stage 132 and the tilt stage 134 to adjust the distance between the first and second chucks 110 and 120, as well as the inclination of the second chuck 120 relative to the first chuck 110. In this embodiment, the wafer bonding apparatus 1 adjusts the position and orientation of the first and second chucks 110 and 120 so that the distance and parallelism between them fall within a predetermined allowable range.

[0053] (Step S103) Next, the wafer bonding apparatus 1 adjusts the position, orientation, and curvature of the first and second wafers W1 and W2. More specifically, the wafer bonding apparatus 1 first uses the camera 60 to image the area between the first and second chucks 110 and 120. Then, based on the image data obtained by the camera 60, the wafer bonding apparatus 1 controls the Z stage 132 and the tilt stage 134 to adjust the distance between the first and second wafers W1 and W2 and the inclination of the second wafer W2 relative to the first wafer W1. In this embodiment, the wafer bonding apparatus 1 adjusts the position and orientation of the first and second wafers W1 and W2 so that the distance and parallelism between the first and second wafers W1 and W2 are within a predetermined allowable range, and so that light from the light source 50 is properly incident on the camera 60. By adjusting the distance between the first and second wafers W1 and W2 to within an allowable range, wafers of various thicknesses can be accommodated.

[0054] Furthermore, the wafer bonding apparatus 1 adjusts the curvature of the first and second wafers W1 and W2 by controlling the adjustment valve 15, which acts as an adjustment unit, based on image data obtained by imaging the above region with the camera 60, thereby adjusting the suction holding force of the first and second chucks 110 and 120 in units of divided regions. For example, if the first wafer W1 is bending downward due to its own weight, the control unit 40 selectively increases the suction holding force of the central divided region of the first chuck 110 to eliminate the bending (curvature) of the first wafer W1.

[0055] (Step S104) Next, the wafer bonding apparatus 1 aligns the first and second wafers W1 and W2. More specifically, the wafer bonding apparatus 1 first images the alignment marks of the first and second wafers W1 and W2 using multiple infrared cameras 112. Then, based on the image data obtained by imaging the alignment marks with the infrared cameras 112, the wafer bonding apparatus 1 controls the XY stage 131 and the theta stage 133 to align the first and second wafers W1 and W2.

[0056] (Step S105) Next, the wafer bonding apparatus 1 starts imaging the bonding process of the first and second wafers W1 and W2. More specifically, the wafer bonding apparatus 1 starts capturing video of the bonding process of the first and second wafers W1 and W2 using the camera 60.

[0057] (Step S106) The wafer bonding apparatus 1 then bonds the first and second wafers W1 and W2. More specifically, the wafer bonding apparatus 1 controls the bonding section 10 to bond the first wafer W1 and the second wafer W2.

[0058] Figures 5A to 5E illustrate an example of the wafer bonding process. In the wafer bonding process, first, with the first and second wafers W1 and W2 held by the first and second chucks 110 and 120, the first and second pressing members 111 and 121 move toward the back surfaces of the first and second wafers (see Figure 5A). Then, the first and second pressing members 111 and 121 come into contact with the back surfaces of the first and second wafers W1 and W2, respectively (see Figure 5B).

[0059] Next, the first and second pressing members 111 and 121 press the central portions of the first and second wafers W1 and W2, causing them to bend so that their central portions are close together (see Figure 5C). Then, the second chuck 120 rises, bringing the central portions of the first wafer W1 and the second wafer W2 into contact (see Figure 5D). Subsequently, the suction holding of the first wafer W1 by the first chuck 110 is released, causing the contact area between the first wafer W1 and the second wafer W2 to expand from the center towards the periphery, and the first wafer W1 and the second wafer W2 are joined together (see Figure 5E).

[0060] (Step S107) Subsequently, the wafer bonding apparatus 1 terminates imaging of the bonding process of the first and second wafers W1 and W2. More specifically, the wafer bonding apparatus 1 stops capturing video with the camera 60. The image data obtained by imaging the bonding process of the first and second wafers W1 and W2 with the camera 60 is stored in the storage unit of the control unit 40.

[0061] (Step S108) Next, the wafer bonding apparatus 1 performs a three-dimensional reconstruction of the image data. More specifically, the wafer bonding apparatus 1 generates three-dimensional image data showing the bonding process of the first and second wafers W1 and W2 by applying a radon transformation to image data obtained by imaging the first and second wafers W1 and W2 during bonding using multiple cameras 60. Furthermore, the wafer bonding apparatus 1 generates multiple three-dimensional image data (three-dimensional moving image data) showing the behavior of the first and second wafers W1 and W2 during the bonding process by repeatedly applying the radon transformation to consecutive image data at predetermined time intervals (for example, every 10 milliseconds). Note that the radon transformation itself is a well-known technique, so a detailed explanation is omitted.

[0062] Figure 6 shows an example of an image 200 captured by camera 60. As shown in Figure 6, the image 200 includes images of the sides of the first and second chucks 110 and 120, and images of the first and second wafers W1 and W2. The images of the sides of the first and second chucks 110 and 120 include images of alignment marks 114 and 124 for aligning multiple cameras 60.

[0063] In the wafer bonding apparatus 1 of this embodiment, the image of the region G between the first wafer W1 and the second wafer W2 has higher brightness than the images of the first and second chucks 110, 120 and the first and second wafers W1, W2, due to the light from the light source 50. Therefore, according to the wafer bonding apparatus 1 of this embodiment, the captured image 200 obtained by imaging the region between the first and second chucks 110, 120 with the camera 60 is an image in which the boundary B1 between the first wafer W1 and region G and the boundary B2 between the second wafer W2 and region G are clearly defined.

[0064] Furthermore, according to the wafer bonding apparatus 1 of this embodiment, eight image data obtained by simultaneously imaging the first and second wafers W1 and W2 from different angles using eight cameras 60 are reconstructed in three dimensions to generate three-dimensional image data (three-dimensional model) showing the bonding scene between the first wafer W1 and the second wafer W2. In addition, three-dimensional reconstruction is repeatedly performed on consecutive image data at predetermined time intervals (for example, every 10 milliseconds) to generate three-dimensional dynamic image data showing the behavior of the first and second wafers W1 and W2 during the bonding process (approximately 1 second).

[0065] (Step S109) Next, the wafer bonding apparatus 1 determines whether the bonding of the first and second wafers W1 and W2 is successful. More specifically, the wafer bonding apparatus 1 inputs the 3D video data generated in step S108 into a learning model that has learned the relationship between the behavior of the two wafers and the bonding success or failure of the two wafers, and determines whether the bonding of the first and second wafers W1 and W2 is successful.

[0066] (Step S110) Then, the wafer bonding apparatus 1 displays the bonding success or failure result on the display and terminates the process. More specifically, the wafer bonding apparatus 1 displays the bonding success or failure result determined by the learning model in step S109 on the display along with a video image based on 3D video data, and terminates the process.

[0067] As described above, according to the flowchart shown in Figure 4, the bonding process of the first and second wafers W1 and W2 is captured by multiple cameras 60, and three-dimensional video data showing the behavior of the first and second wafers W1 and W2 during the bonding process is generated. Based on the three-dimensional video data, the quality of the bonding of the first and second wafers W1 and W2 is determined. In other words, the bonding of the first and second wafers W1 and W2 is measured and evaluated in situ.

[0068] In the embodiment described above, the bonding quality of the first and second wafers W1 and W2 was determined by a learning model that learned the relationship between three-dimensional video data showing the behavior of the two wafers and the bonding quality of the wafers. However, unlike the embodiment described above, the bonding quality of the first and second wafers W1 and W2 may be determined by an operator by displaying a video based on the three-dimensional video data on a display.

[0069] <Reference example> In the embodiment described above, the region between the first chuck 110 and the second chuck 120 was imaged by multiple cameras 60, and the resulting image data was reconstructed in three dimensions to generate three-dimensional image data showing the bonding scene of the first and second wafers W1 and W2. However, the bonding scene of the first and second wafers may be imaged without performing three-dimensional reconstruction.

[0070] The wafer bonding apparatus according to the reference example includes a bonding portion that bonds the first wafer and the second wafer by adsorbing and holding the first wafer and the second wafer with first chucks and second chucks arranged facing each other, and bringing the first wafer and the second wafer into contact with each other while bending at least one of the first wafer and the second wafer so that the central portions of the first wafer and the second wafer are close together; a light source arranged to the side of the first chuck and the second chuck and irradiating light into the area between the first chuck and the second chuck; and a camera arranged on the opposite side of the light source with the first chuck and the second chuck in between and imaging the area irradiated by light from the light source.

[0071] Except for the fact that the image data obtained by imaging the above region with a camera is not reconstructed in three dimensions, the configuration of the wafer bonding apparatus according to the reference example is the same as the configuration of the wafer bonding apparatus 1 according to the above embodiment, so a detailed explanation will be omitted. According to the wafer bonding apparatus according to the reference example, the distribution of the spacing between the unbonded portions of the first wafer and the second wafer at the bonding scene of the first and second wafers (shape of region G shown in Figure 6) can be determined from the image data obtained by imaging the region between the first and second chucks with a camera.

[0072] The present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the claims.

[0073] For example, in the embodiment described above, 3D reconstruction was performed after the imaging of the bonding process of the two wafers was completed, and 3D image data showing the bonding scene of the first and second wafers was generated. However, the timing of 3D reconstruction is not limited to after the imaging of the bonding process is completed, and 3D reconstruction may be performed concurrently with the video imaging of the bonding process.

[0074] Furthermore, in the embodiments described above, when joining the first and second wafers W1 and W2, the first and second wafers W1 and W2 are pressed by the first and second pressing members 111 and 121 to bend both wafers W1 and W2 as an example. However, the method of bringing the central portions of the first and second wafers close together is not limited to the embodiments described above, and only one of the first and second wafers W1 and W2 may be pressed by the pressing member to bend only one of the first and second wafers W1 and W2. Alternatively, the central portion of at least one of the wafer holding surfaces of the first and second chucks may be bulging, and the wafer may be bent by adsorbing and holding the wafer along the bulging wafer holding surface.

[0075] Furthermore, the above-described embodiment explained the case in which a blue laser light source emitting blue light is used as the light source. However, the light source is not limited to a blue laser light source, and various laser light sources with a central wavelength in the range of 200 nm to 800 nm can be used. Note that if the central wavelength of the laser light source is less than 200 nm, a vacuum environment is required, which is undesirable. Also, if the central wavelength of the laser light source exceeds 800 nm, it is undesirable because general image sensors such as CCDs and CMOSs ​​cannot be used. In addition, the light source is not limited to a laser light source, and a white light source may be used as the light source. In this case, light of the desired wavelength is selectively used by a wavelength selective filter or the like.

[0076] Furthermore, the above-described embodiment was explained using the case where slit light is emitted from the light source as an example. However, the light emitted from the light source is not limited to slit light, and may be light that has a vertical spread. Also, the light emitted from the light source may be light other than linearly polarized light (P-polarized or S-polarized light).

[0077] Furthermore, in the embodiments described above, the case in which multiple distance sensors 113 are provided on the first chuck 110 was explained as an example. However, it is not necessary to provide multiple distance sensors 113, and a single distance sensor may be provided on the first chuck 110. In this case, in the process of step S102, the parallelism of the first and second chucks 110, 120 is not adjusted, and only the distance between the first and second chucks 110, 120 is adjusted.

[0078] Furthermore, in the embodiment described above, alignment marks were imaged using the infrared camera 112 to perform horizontal alignment of the first and second wafers W1 and W2. However, in addition to horizontal alignment, the distance between the first and second wafers W1 and W2 may also be adjusted based on the focal position when the alignment marks are imaged using the infrared camera 112.

[0079] The means and methods for performing various processing in the wafer bonding apparatus 1 according to the above embodiment can be implemented by either a dedicated hardware circuit or a programmed computer. The program may be provided, for example, on a computer-readable recording medium such as a USB memory or DVD-ROM, or it may be provided online via a network such as the Internet. In this case, the program recorded on the computer-readable recording medium is usually transferred to and stored in a storage unit such as an HDD. Furthermore, the program may be provided as a standalone application software, or it may be incorporated into the software of the wafer bonding apparatus 1 as a function of the apparatus. [Explanation of symbols]

[0080] 1. Wafer bonding apparatus, 10 joints, 15 Adjustment valve (adjustment part), 20 Measurement unit, 30 Plasma irradiation section, 40 Control Unit (Generation Unit, 1st to 3rd Control Units), 50,50a,50b light source, 60, 60a~60h camera, 71 Annular member, 72 Drive mechanism (third drive unit), 110,120 Chuck, 111,121 Pressing member, 112 Infrared camera, 113 Distance sensor, 114,124 alignment marks, 130 Drive unit, 131 XY Stages, 132 Z-stage (first drive unit), 133 Theta Stage, 134 Tilt stage (second drive unit), 200 captured images, B1,B2 boundary, G area, W1, W2 wafers.

Claims

1. A joining portion is formed by bringing the first wafer and the second wafer into contact with each other, while holding the first wafer and the second wafer by adsorption using a first chuck and a second chuck arranged opposite each other, and bending at least one of the first wafer and the second wafer so that their central portions are close together, and bringing the first wafer and the second wafer into contact. A light source is positioned to the side of the first chuck and the second chuck, and illuminates the area between the first chuck and the second chuck with light. Multiple cameras are positioned on opposite sides of the light source, with the first and second chucks in between, and each camera captures the area illuminated by the light source. A generation unit generates three-dimensional image data showing the bonding scene between the first wafer and the second wafer by three-dimensionally reconstructing image data obtained by imaging the region with the plurality of cameras during the bonding of the first wafer and the second wafer, A wafer bonding apparatus having the following features.

2. Each camera continuously images the region at a predetermined imaging cycle. The wafer bonding apparatus according to claim 1, wherein the generation unit generates a plurality of three-dimensional image data showing the behavior of the first wafer and the second wafer during the bonding process of the first wafer and the second wafer, based on image data that is continuous at predetermined time intervals.

3. The wafer bonding apparatus according to claim 1 or 2, wherein the number of cameras is greater than the number of light sources.

4. A first drive unit that moves the first chuck and the second chuck closer together and further apart, A first control unit adjusts the distance between the first wafer and the second wafer by controlling the first drive unit based on image data obtained by imaging the region with the camera, A wafer bonding apparatus according to claim 1 or 2, further comprising the above.

5. A second drive unit that changes the tilt of at least one of the first chuck and the second chuck, A second control unit adjusts the tilt of at least one of the first wafer and the second wafer by controlling the second drive unit based on image data obtained by imaging the region with the camera, A wafer bonding apparatus according to claim 1 or 2, further comprising the above.

6. An adjustment unit for adjusting the suction holding force of at least one of the first chuck and the second chuck, A third control unit controls the adjustment unit based on image data obtained by imaging the region with the camera, thereby adjusting the warpage of at least one of the first wafer and the second wafer. A wafer bonding apparatus according to claim 1 or 2, further comprising the above.

7. The wafer bonding apparatus according to claim 1 or 2, further comprising a third drive unit for moving the light source and the camera between a measurement position in which the light source and the camera are located around the first chuck and the second chuck, and a retracted position in which the light source and the camera are located away from the measurement position.

8. The wafer bonding apparatus according to claim 1 or 2, wherein the light source is configured to irradiate with P-polarized or S-polarized light.

9. The wafer bonding apparatus according to claim 1 or 2, wherein the light source is configured to be adjustable in at least one of the light divergence angle and light intensity.

10. The wafer bonding apparatus according to claim 1 or 2, wherein the light source is a laser light source having a central wavelength in the range of 200 nm to 800 nm.

11. The wafer bonding apparatus according to claim 1 or 2, further comprising an infrared camera for imaging alignment marks on the first wafer and the second wafer.

12. The wafer bonding apparatus according to claim 1 or 2, further comprising a distance sensor for detecting the distance between the first chuck and the second chuck.

13. The wafer bonding apparatus according to claim 1 or 2, further comprising a plasma irradiation unit provided separately from the bonding unit for irradiating the first wafer and the second wafer with plasma before they are held by the first chuck and the second chuck.

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