Bonding device, bonding system, bonding method, program and computer storage media

Abstract

To inspect the condition of the substrate bonding process and to properly perform the bonding process.SOLUTION: A bonding device for bonding an upper wafer WU and a lower wafer WL has an upper chuck 140 that draws a vacuum, and sucks and holds the upper wafer WU on its lower surface, a lower chuck 141 that is provided below the upper chuck 140 and draws a vacuum, and sucks and holds the lower wafer WL on its upper surface, a pushing member 190 that is provided on the upper chuck 140 and presses the center of the upper wafer WU, and a sensor 175 provided on the upper chuck 140 and detects the state of contact between the upper wafer WU and the lower wafer WL. The sensor 175 measures the flow rate or pressure of gas flowing through the suction pipe for drawing a vacuum to the upper wafer WU.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a bonding apparatus for bonding substrates together. [Background technology]

[0002] In recent years, semiconductor devices have become increasingly highly integrated. When multiple highly integrated semiconductor devices are arranged in a horizontal plane and connected to each other by wiring to produce a product, the wiring length increases, which can lead to higher wiring resistance and wiring delays.

[0003] Therefore, it has been proposed to use a three-dimensional integration technique for stacking semiconductor devices three-dimensionally. In this three-dimensional integration technique, two semiconductor wafers (hereinafter referred to as "wafers") are bonded using a bonding system described in Patent Document 1, for example. For example, the bonding system includes a surface modification device for modifying the surfaces of the wafers to be bonded, a surface hydrophilization device for hydrophilizing the surfaces of the wafers modified by the surface modification device, and a bonding device for bonding the wafers whose surfaces have been hydrophilized by the surface hydrophilization device. In this bonding system, the surface modification device performs plasma processing on the surfaces of the wafers to modify the surfaces, and the surface hydrophilization device supplies pure water to the surfaces of the wafers to hydrophilize the surfaces, and then the bonding device bonds the wafers to each other by van der Waals forces and hydrogen bonds (intermolecular forces).

[0004] The bonding device has an upper chuck that holds one wafer (hereinafter referred to as "upper wafer") on its lower surface, a lower chuck that is provided below the upper chuck and holds another wafer (hereinafter referred to as "lower wafer") on its upper surface, and a pressing member that is provided on the upper chuck and presses the center of the upper wafer. In this bonding device, the upper wafer held by the upper chuck and the lower wafer held by the lower chuck are arranged facing each other, and the pressing member presses the center of the upper wafer and the center of the lower wafer to bring them into contact with each other, and the centers are bonded to each other to form a bonding region. After that, a so-called bonding wave is generated in which the bonding region expands from the center of the wafer to the outer periphery. Then, the upper wafer and the lower wafer are bonded. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-039364 A Summary of the Invention [Problem to be solved by the invention]

[0006] In order to suppress distortion of the laminated wafers after bonding, it is preferable that the bonding wave expands evenly, i.e., concentrically, from the center of the wafer to the outer periphery. However, in the bonding device described in the above-mentioned Patent Document 1, the bonding wave is not monitored, and even if the bonding wave expands non-uniformly, it cannot be grasped. Therefore, there is room for improvement in the conventional wafer bonding process.

[0007] The present invention has been made in view of the above-mentioned points, and has an object to inspect the state of a bonding process for substrates and to perform the bonding process appropriately. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a bonding device for bonding substrates together, comprising a first holding section for adsorbing and holding a first substrate by its underside, a second holding section provided below the first holding section for adsorbing and holding a second substrate by its upper surface, a pressing member provided on the first holding section for pressing a center of the first substrate, a substrate detection section provided on the first holding section for detecting a contact state between the first substrate and the second substrate, and the substrate detection section measures the flow rate or pressure of gas flowing through a suction tube for vacuuming the first substrate.

[0009] According to the present invention, the substrate detection unit can detect the first substrate held by the first holding unit being detached from the first holding unit. When the first substrate is detached, the first substrate falls onto the second substrate and comes into contact with the second substrate, and the first substrate and the second substrate are bonded by intermolecular forces. Therefore, by detecting the detachment of the first substrate, the bonding wave can be grasped, and the state of the wafer bonding process can be inspected. Then, for example, if the bonding wave is uniform (if the state of the bonding process is normal), the bonding process can be continued under the same processing conditions. On the other hand, for example, if the bonding wave is non-uniform (if the state of the bonding process is abnormal), the processing conditions can be corrected and the bonding process can be performed. Therefore, according to the present invention, the substrate bonding process can be performed appropriately. Effect of the Invention

[0010] According to the present invention, the state of the bonding process of the substrates can be inspected and the bonding process can be performed appropriately. [Brief description of the drawings]

[0011] [Figure 1] 1 is a plan view showing an outline of a configuration of a joining system according to an embodiment of the present invention. [Diagram 2] 1 is a side view showing an outline of an internal configuration of a joining system according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a side view showing an outline of the configuration of an upper wafer and a lower wafer. [Figure 4] FIG. 2 is a cross-sectional view showing an outline of the configuration of a joining device. [Diagram 5] FIG. 2 is a vertical cross-sectional view showing an outline of the configuration of a joining device. [Figure 6] 2 is a longitudinal cross-sectional view showing an outline of the configuration of an upper chuck, an upper chuck holding portion, and a lower chuck. FIG. [Figure 7] FIG. [Figure 8] FIG. 13 is an explanatory diagram showing the expansion of a bonding area between wafers in a conventional method. [Figure 9] 11 is a graph showing an example of an output result of a sensor. [Figure 10] 1 is a flowchart showing main steps of a wafer bonding process. [Figure 11] FIG. 2 is an explanatory diagram showing a state in which an upper wafer and a lower wafer are arranged opposite each other. [Figure 12] 11 is an explanatory diagram showing a state in which the central portion of the upper wafer and the central portion of the lower wafer are pressed into contact with each other. FIG. [Figure 13] 1 is an explanatory diagram showing a state in which the bonding between the upper wafer and the lower wafer is diffused from the center to the outer periphery. FIG. [Figure 14] 1 is an explanatory diagram showing a state in which the surface of the upper wafer and the surface of the lower wafer are brought into contact with each other; [Figure 15] FIG. 2 is an explanatory diagram showing a state in which the upper wafer and the lower wafer are bonded together. [Figure 16] FIG. 13 is a plan view of an upper chuck showing an arrangement of sensors according to another embodiment. [Figure 17] FIG. 13 is a plan view of an upper chuck showing an arrangement of sensors according to another embodiment. [Figure 18] 13 is a longitudinal sectional view showing an outline of the configuration of an upper chuck, an upper chuck holding portion, and a lower chuck according to another embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to the embodiment described below.

[0013] <1. Configuration of the joining system> First, a description will be given of the configuration of a joint system according to the present embodiment. Fig. 1 is a plan view showing an outline of the configuration of a joint system 1. Fig. 2 is a side view showing an outline of the internal configuration of the joint system 1.

[0014] In the bonding system 1, as shown in Fig. 3, for example, two substrates, wafers WU and WL, are bonded. Hereinafter, the wafer arranged on the upper side is referred to as the "upper wafer WU" as the first substrate, and the wafer arranged on the lower side is referred to as the "lower wafer WL" as the second substrate. The bonding surface to which the upper wafer WU is bonded is referred to as the "front surface WU1," and the surface opposite the front surface WU1 is referred to as the "back surface WU2." Similarly, the bonding surface to which the lower wafer WL is bonded is referred to as the "front surface WL1," and the surface opposite the front surface WL1 is referred to as the "back surface WL2." Then, in the bonding system 1, the upper wafer WU and the lower wafer WL are bonded to form an overlapped wafer WT as an overlapped substrate.

[0015] As shown in FIG. 1, the bonding system 1 has a configuration in which, for example, a loading / unloading station 2 through which cassettes CU, CL, and CT capable of housing multiple wafers WU, WL and multiple overlapping wafers WT, respectively, are loaded and unloaded from the outside, and a processing station 3 equipped with various processing devices that perform predetermined processing on the wafers WU, WL, and overlapping wafers WT, are integrally connected.

[0016] The carry-in / out station 2 is provided with a cassette placement table 10. The cassette placement table 10 is provided with a plurality of, for example, four, cassette placement plates 11. The cassette placement plates 11 are arranged in a row in the horizontal X direction (the up-down direction in FIG. 1). The cassettes CU, CL, and CT can be placed on these cassette placement plates 11 when carrying the cassettes CU, CL, and CT into and out of the bonding system 1. In this way, the carry-in / out station 2 is configured to be able to hold a plurality of upper wafers WU, a plurality of lower wafers WL, and a plurality of overlapped wafers WT. The number of cassette placement plates 11 is not limited to this embodiment and can be set arbitrarily. Also, one of the cassettes may be used for recovering abnormal wafers. That is, it is a cassette that can separate a wafer in which an abnormality has occurred in the bonding between the upper wafer WU and the lower wafer WL due to various factors from other normal overlapped wafers WT. In this embodiment, of the multiple cassettes CT, one cassette CT is used for recovering abnormal wafers, and the other cassettes CT are used for storing normal overlapped wafers WT.

[0017] The loading / unloading station 2 is provided with a wafer transport section 20 adjacent to the cassette mounting table 10. The wafer transport section 20 is provided with a wafer transport device 22 that is movable on a transport path 21 extending in the X direction. The wafer transport device 22 is also movable in the vertical direction and around the vertical axis (θ direction), and can transport wafers WU, WL, and overlapped wafers WT between the cassettes CU, CL, and CT on each cassette mounting plate 11 and transition devices 50 and 51 in a third processing block G3 of the processing station 3, which will be described later.

[0018] In the processing station 3, a plurality of processing blocks, for example three processing blocks G1, G2, G3 equipped with various devices are provided. For example, a first processing block G1 is provided on the front side of the processing station 3 (the negative side in the X direction in FIG. 1), and a second processing block G2 is provided on the rear side of the processing station 3 (the positive side in the X direction in FIG. 1). In addition, a third processing block G3 is provided on the loading / unloading station 2 side of the processing station 3 (the negative side in the Y direction in FIG. 1).

[0019] For example, the first processing block G1 is provided with a surface modification device 30 for modifying the surfaces WU1, WL1 of the wafers WU, WL. In the surface modification device 30, for example, in a reduced pressure atmosphere, oxygen gas or nitrogen gas, which is a processing gas, is excited to be turned into plasma and ionized. The oxygen ions or nitrogen ions are irradiated onto the surfaces WU1, WL1, so that the surfaces WU1, WL1 are subjected to plasma processing and modified.

[0020] For example, in the second processing block G2, a surface hydrophilization device 40 that hydrophilizes the surfaces WU1, WL1 of the wafers WU, WL using, for example, pure water and cleans the surfaces WU1, WL1, and a bonding device 41 that bonds the wafers WU, WL are arranged in this order in the horizontal Y direction from the load / unload station 2 side. The configuration of the bonding device 41 will be described later.

[0021] In the surface hydrophilization device 40, pure water is supplied onto the wafers WU, WL while rotating the wafers WU, WL held by, for example, a spin chuck. Then, the supplied pure water diffuses over the surfaces WU1, WL1 of the wafers WU, WL, and the surfaces WU1, WL1 are hydrophilized.

[0022] For example, in the third processing block G3, transition devices 50 and 51 for the wafers WU and WL and the overlapped wafer WT are provided in two stages in this order from the bottom as shown in FIG.

[0023] 1, a region surrounded by the first processing block G1 to the third processing block G3 defines a wafer transfer region 60. In the wafer transfer region 60, a wafer transfer device 61, for example, is disposed.

[0024] The wafer transfer device 61 has a transfer arm that is movable, for example, in the vertical direction, horizontal direction (Y direction, X direction), and around the vertical axis. The wafer transfer device 61 moves within the wafer transfer region 60 and can transfer the wafers WU, WL, and overlapped wafer WT to predetermined devices within the surrounding first processing block G1, second processing block G2, and third processing block G3.

[0025] The bonding system 1 described above is provided with a control unit 70 as shown in FIG. The control unit 70 is, for example, a computer, and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the wafers WU, WL, and overlapped wafer WT in the bonding system 1. The program storage unit also stores a program for controlling the operation of the drive systems of the above-mentioned various processing devices and transport devices, and for realizing a wafer bonding process described below in the bonding system 1. The program may be recorded in a computer-readable storage medium H, such as a computer-readable hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), or a memory card, and may be installed in the control unit 70 from the storage medium H.

[0026] <2. Configuration of the bonding device> Next, the configuration of the above-mentioned joining device 41 will be described.

[0027] <2-1. Overall configuration of the bonding device> The bonding apparatus 41 has a processing vessel 100 whose interior can be sealed as shown in Fig. 4 and Fig. 5. A loading / unloading port 101 for the wafers WU, WL, and overlapping wafer WT is formed on the side of the processing vessel 100 on the wafer transfer region 60 side, and an opening / closing shutter 102 is provided at the loading / unloading port 101.

[0028] The inside of the processing vessel 100 is divided into a transfer region T1 and a processing region T2 by an inner wall 103. The above-mentioned loading / unloading port 101 is formed on a side surface of the processing vessel 100 in the transfer region T1. The inner wall 103 also has loading / unloading ports 104 for the wafers WU, WL, and the overlapped wafer WT.

[0029] A transition 110 for temporarily placing the wafers WU, WL, and overlapping wafer WT is provided on the positive side of the transfer region T1 in the Y direction. The transition 110 is formed, for example, in two stages, and any two of the wafers WU, WL, and overlapping wafer WT can be placed thereon at the same time.

[0030] A wafer transfer mechanism 111 is provided in the transfer region T1. The wafer transfer mechanism 111 has a transfer arm that is movable, for example, in the vertical direction, the horizontal direction (X direction, Y direction), and around the vertical axis. The wafer transfer mechanism 111 can transfer the wafers WU, WL, and overlapped wafers WT within the transfer region T1 or between the transfer region T1 and the processing region T2.

[0031] A position adjustment mechanism 120 for adjusting the horizontal orientation of the wafers WU and WL is provided on the negative Y-direction side of the transfer region T1. The position adjustment mechanism 120 has a base 121 equipped with a holder (not shown) for holding and rotating the wafers WU and WL, and a detector 122 for detecting the positions of the notches of the wafers WU and WL. The position adjustment mechanism 120 rotates the wafers WU and WL held on the base 121 while detecting the positions of the notches of the wafers WU and WL with the detector 122, thereby adjusting the positions of the notches to adjust the horizontal orientation of the wafers WU and WL. The structure for holding the wafers WU and WL on the base 121 is not particularly limited, and various structures such as a pin chuck structure or a spin chuck structure may be used.

[0032] Further, an inversion mechanism 130 that inverts the front and back sides of the upper wafer WU is provided in the transfer region T1. The inversion mechanism 130 has a holding arm 131 that holds the upper wafer WU. The holding arm 131 extends in the horizontal direction (X direction). Furthermore, the holding arm 131 is provided with holding members 132 that hold the upper wafer WU at, for example, four locations.

[0033] The holding arm 131 is supported by a drive unit 133 having, for example, a motor. The drive unit 133 allows the holding arm 131 to rotate around a horizontal axis. The holding arm 131 is also rotatable around the drive unit 133 and is also movable in the horizontal direction (X direction). Below the drive unit 133, another drive unit (not shown) having, for example, a motor is provided. The other drive unit allows the drive unit 133 to move in the vertical direction along a support column 134 extending in the vertical direction. In this way, the drive unit 133 allows the upper wafer WU held by the holding member 132 to rotate around a horizontal axis and move in the vertical and horizontal directions. The upper wafer WU held by the holding member 132 can also rotate around the drive unit 133 and move between the position adjustment mechanism 120 and an upper chuck 140, which will be described later.

[0034] In the processing region T2, there are provided an upper chuck 140 as a first holding part which adsorbs and holds the upper wafer WU on its lower surface, and a lower chuck 141 as a second holding part which places the lower wafer WL on its upper surface and adsorbs and holds it. The lower chuck 141 is provided below the upper chuck 140 and is configured so as to be able to be arranged opposite the upper chuck 140. In other words, the upper wafer WU held by the upper chuck 140 and the lower wafer WL held by the lower chuck 141 can be arranged so as to face each other.

[0035] The upper chuck 140 is held by an upper chuck holding part 150 provided above the upper chuck 140. The upper chuck holding part 150 is provided on the ceiling surface of the processing vessel 100. That is, the upper chuck 140 is fixed to the processing vessel 100 via the upper chuck holding part 150.

[0036] The upper chuck holding part 150 is provided with an upper imaging part 151 which captures an image of the front surface WL1 of the lower wafer WL held by the lower chuck 141. That is, the upper imaging part 151 is provided adjacent to the upper chuck 140. The upper imaging part 151 may be, for example, a CCD camera.

[0037] The lower chuck 141 is supported by a lower chuck stage 160 provided below the lower chuck 141. The lower chuck stage 160 is provided with a lower imaging unit 161 that images the front surface WU1 of the upper wafer WU held by the upper chuck 140. That is, the lower imaging unit 161 is provided adjacent to the lower chuck 141. The lower imaging unit 161 may be, for example, a CCD camera.

[0038] The lower chuck stage 160 is supported by a first lower chuck moving part 162 provided below the lower chuck stage 160, and the first lower chuck moving part 162 is further supported by a support base 163. The first lower chuck moving part 162 is configured to move the lower chuck 141 in the horizontal direction (X direction) as described below. In addition, the first lower chuck moving part 162 is configured to be able to move the lower chuck 141 freely in the vertical direction and to rotate it around a vertical axis.

[0039] The support table 163 is provided on the lower surface side of the support table 163 and attached to a pair of rails 164, 164 extending in the horizontal direction (X direction). The support table 163 is configured to be freely movable along the rails 164 by a first lower chuck moving part 162. The first lower chuck moving part 162 is moved by, for example, a linear motor (not shown) provided along the rails 164.

[0040] The pair of rails 164, 164 is disposed on a second lower chuck moving part 165. The second lower chuck moving part 165 is provided on the lower surface side of the second lower chuck moving part 165 and is attached to a pair of rails 166, 166 extending in the horizontal direction (Y direction). The second lower chuck moving part 165 is configured to be movable along the rails 166, that is, configured to move the lower chuck 141 in the horizontal direction (Y direction). The second lower chuck moving part 165 is moved by, for example, a linear motor (not shown) provided along the rails 166. The pair of rails 166, 166 is disposed on a mounting table 167 provided on the bottom surface of the processing vessel 100.

[0041] <2-2. Upper chuck configuration> Next, the detailed configuration of the upper chuck 140 of the joining device 41 will be described.

[0042] The upper chuck 140 employs a pin chuck system as shown in Fig. 6 and Fig. 7. The upper chuck 140 has a main body 170 having a diameter equal to or larger than the diameter of the upper wafer WU in a plan view. A plurality of pins 171 that come into contact with the back surface WU2 of the upper wafer WU are provided on the lower surface of the main body 170. Note that the pins 171 are not shown in Fig. 7.

[0043] Further, a plurality of suction parts 172 to 174 that suck the upper wafer WU by vacuum drawing are provided on the lower surface of the main body part 170. The suction parts 172 to 174 each have the same height as the pin 171, and come into contact with the back surface WU2 of the upper wafer WU.

[0044] The first suction portion 172 has an arc shape in a plan view. A plurality of the first suction portions 172 (e.g., eight first suction portions 172) are arranged at predetermined intervals in the circumferential direction on the outer periphery of the main body portion 170 concentrically with the main body portion 170.

[0045] A first vacuum pump 172b is connected via a first suction pipe 172a to each of the eight first suction parts 172. The eight first suction parts 172 can individually suction the upper wafer WU by vacuum drawing by the first vacuum pump 172b.

[0046] The second suction portion 173 has an arc shape in a plan view, similar to the first suction portion 172. The second suction portion 173 is arranged at predetermined intervals in the circumferential direction on a concentric circle with the main body portion 170, on the inner periphery side of the main body portion 170 relative to the first suction portion 172, in a plurality of units (e.g., eight units). The centers of the first suction portion 172 and the second suction portion 173 are arranged on the center line of the main body portion 170.

[0047] A second vacuum pump 173b is connected via a second suction pipe 173a to each of the eight second suction units 173. By drawing a vacuum with the second vacuum pump 173b, the eight second suction units 173 can individually suction the upper wafer WU.

[0048] The third suction unit 174 has a circular ring shape in a plan view. The third suction unit 174 is arranged concentrically with the main body unit 170, closer to the inner circumference of the main body unit 170 than the second suction unit 173. A third vacuum pump 174b is connected to the third suction unit 174 via a third suction pipe 174a. The third suction unit 174 can adsorb the upper wafer WU by vacuuming using the third vacuum pump 174b.

[0049] The main body 170 is provided with a sensor 175 as a substrate detection unit that detects the separation of the upper wafer WU from the main body 170. A plurality of sensors 175, for example, eight sensors 175, are arranged at predetermined intervals in the circumferential direction on a concentric circle with the main body 170 between the first suction unit 172 and the second suction unit 173. That is, the sensor 175, the center of the first suction unit 172, and the center of the second suction unit 173 are arranged on the same center line of the main body 170. Details of the types and arrangements of these sensors 175 will be described later.

[0050] A through hole 176 is formed in the center of the main body 170, penetrating the main body 170 in the thickness direction. The center of the main body 170 corresponds to the center of the upper wafer WU attracted and held by the upper chuck 140. A tip end of an actuator portion 191 of a pressing member 190, which will be described later, is inserted into the through hole 176.

[0051] <2-3. Details of the upper chuck sensor> Next, details of the above-mentioned sensor 175 and a method of controlling the suction units 172 to 174 using the inspection results of the sensor 175 will be described.

[0052] As described below, when bonding the upper wafer WU and the lower wafer WL, first, the center of the upper wafer WU is pressed down to contact the center of the lower wafer WL, and the centers of the upper wafer WU and the lower wafer WL are bonded by intermolecular forces to form a bonding region at the center of both wafers. After that, a bonding wave is generated in which the bonding region expands from the center of both wafers WU and WL toward the outer periphery, and the surfaces WU1 and WL1 of the upper wafer WU and the lower wafer WL are bonded together over the entire surfaces.

[0053] A sensor 175 is provided on the main body 170 to detect the bonding wave.

[0054] Various sensors can be used for the sensor 175. For example, a reflective fiber sensor can be used for the sensor 175. In this case, the sensor 175 emits light toward the upper wafer WU, and the sensor 175 receives the reflected light and measures the amount of received light. Then, by measuring the amount of received reflected light, the orthogonality between the optical axis and the upper wafer WU can be grasped. That is, when the amount of reflected light is small, the orthogonality between the optical axis and the upper wafer WU is large (the inclination of the upper wafer WU is large), which means that the upper wafer WU is separated from the upper chuck 140 but is not in contact with the lower wafer WL. On the other hand, when the amount of reflected light is large, the orthogonality between the optical axis and the upper wafer WU is small (the inclination of the upper wafer WU is small), which means that the upper wafer WU is separated from the upper chuck 140 and is in contact with the lower wafer WL. Therefore, by measuring the amount of reflected light with the sensor 175, the contact state between the upper wafer WU and the lower wafer WL at the sensor 175 (in other words, the release state of the upper wafer WU from the upper chuck 140) can be detected, and the bonding wave can be grasped.

[0055] Also, for example, a capacitance sensor or a distance measuring sensor may be used as the sensor 175. When a capacitance sensor is used, the distance between the upper chuck 140 and the upper wafer WU can be measured by measuring the capacitance with the upper wafer WU. When a distance measuring sensor is used, the sensor 175 emits laser light to the upper wafer WU and the sensor 175 receives the reflected light, thereby measuring the distance between the upper chuck 140 and the upper wafer WU. By measuring the distance between the upper chuck 140 and the upper wafer WU in this manner, the sensor 175 can detect the contact state between the upper wafer WU and the lower wafer WL (in other words, the release state of the upper wafer WU from the upper chuck 140) and grasp the bonding wave.

[0056] Also, for example, a fluid sensor may be used for the sensor 175. In this case, a suction pad (not shown) is provided on the main body 170, that is, a suction pad is provided at the position of the reference symbol "175" shown in Figs. 6 and 7, and the sensor 175 is provided on a suction tube (not shown) connected to the suction pad. The suction pad is not intended to hold the upper wafer WU by suction, but to suction the upper wafer WU with a minute pressure, for example, about -10 kPa, that does not affect the bonding wave. The sensor 175 measures the flow rate or pressure of the gas flowing through each suction tube. For example, when the upper wafer WU is detached from the upper chuck 140, the flow of the gas in the suction tube changes, and the flow rate and pressure of the gas change. The sensor 175 measures the change in the air flow in the suction tube, and can detect the detachment of the upper wafer WU from the upper chuck 140 (in other words, the abutting state of the upper wafer WU and the lower wafer WL), and can grasp the bonding wave. The sensor 175 may be provided in the first suction tube 172a of the first suction unit 172 and the second suction tube 173a of the second suction unit 173, respectively.

[0057] As described above, the sensors 175 are arranged at predetermined intervals in the circumferential direction on a circle concentric with the main body 170 between the first suction part 172 and the second suction part 173. Next, the arrangement of the sensors 175 will be described.

[0058] The arrangement of the sensor 175 is determined according to the physical properties of the upper wafer WU, such as anisotropy of Young's modulus and Poisson's ratio. Fig. 8 is an explanatory diagram showing the expansion of the bonding area between wafers in the conventional method. The present inventors have found that, as shown in Fig. 8, when performing a bonding process, the bonding area A does not expand concentrically but expands unevenly. Fig. 8 is a plan view of the upper wafer WU held by the upper chuck 140 as viewed from below.

[0059] The upper wafer WU is a single crystal silicon wafer with a crystal orientation of

[0100] in a direction perpendicular to the surface WU1. The notch portion N of the upper wafer WU is formed on the outer edge of the

[0011] crystal orientation of the upper wafer WU. The bonding region A expands faster in a 45° periodic direction (45°, 135°, 225°, 315° directions shown in FIG. 8, hereinafter sometimes referred to as a 45° direction) based on a direction from the center of the upper wafer WU toward the

[0010] crystal orientation parallel to the surface WU1 of the upper wafer WU, compared to a 90° periodic direction (0°, 90°, 180°, 270° directions shown in FIG. 8, hereinafter sometimes referred to as a 90° direction) based on a direction from the center of the upper wafer WU toward the

[0010] crystal orientation parallel to the surface WU1 of the upper wafer WU. As a result, the shape of the welded area A, which was circular at the start of welding (when the center is welded), approaches a rectangle with vertices at 45° angles as it expands.

[0060] In this embodiment, eight sensors 175 are provided concentrically with the main body 170, i.e., provided at 90° and 45° angles. Therefore, by using these sensors 175 to detect the separation of the upper wafer WU from the upper chuck 140 and to detect the bonding area A shown in FIG. 8, the bonding wave can be grasped.

[0061] The detection result of the sensor 175 is output to the control unit 70. The control unit 70 controls the operations of the suction units 172 to 174 based on the detection result of the sensor 175.

[0062] 9 is a graph showing an example of the output result of the sensor 175. The horizontal axis of FIG. 9 indicates the elapsed time of the bonding process, and the vertical axis indicates the output result of the sensor 175, i.e., the position of the upper wafer WU relative to the upper chuck 140. When the output result of the sensor 175 is P1 (the upper wafer WU is closer to the upper chuck 140), it indicates that the upper wafer WU is in contact with the upper chuck 140 at the position of the sensor 175, and the bonding region A has not yet arrived. When the detection result of the sensor 175 is P2 (the upper wafer WU is farther from the upper chuck 140), it indicates that the upper wafer WU is away from the upper chuck 140 at the position of the sensor 175, and is in contact with the lower wafer WL, and the bonding region A has arrived.

[0063] Fig. 9(a) shows the case where the bonding area A expands non-uniformly, i.e., into a substantially rectangular shape, as shown in Fig. 8. As described above, the bonding area A expands faster in the 45° direction than in the 90° direction. Therefore, the time difference ΔT between the timing at which the bonding area A arrives in the 45° direction and the timing at which the bonding area A arrives in the 90° direction becomes large.

[0064] Therefore, in order to uniformly expand the bonding area A, the control unit 70 controls the time difference ΔT to fall within a predetermined threshold as shown in FIG. 9(b). Here, there is a correlation between the time difference ΔT and the distortion of the overlapped wafer WT after bonding. The predetermined threshold of ΔT is set based on the allowable range of the distortion of the overlapped wafer WT.

[0065] Specifically, the control unit 70 delays the timing at which the second suction unit 173 releases the upper wafer WU in the 45° direction and advances the timing at which the second suction unit 173 releases the upper wafer WU in the 90° direction. This makes it possible to make the timing at which the bonding region A arrives substantially the same at the positions of the eight sensors 175. This makes it possible to make the expansion of the bonding region A uniform and to make the bonding wave uniform (in a shape close to concentric circles).

[0066] In the present embodiment, the case has been described where the suction timing of second suction unit 173 is controlled based on the detection result of sensor 175, but the suction force of second suction unit 173 may also be controlled. Also, the other suction units 172 and 174 may be controlled based on the detection result of sensor 175.

[0067] <2-4. Structure of the upper chuck holding part> Next, a detailed configuration of the upper chuck holding portion 150 of the joining device 41 will be described.

[0068] 5, the upper chuck holding part 150 has an upper chuck stage 180 provided on an upper surface of the main body part 170 of the upper chuck 140. The upper chuck stage 180 is provided so as to cover at least the upper surface of the main body part 170 in a plan view, and is fixed to the main body part 170 by, for example, screwing. The upper chuck stage 180 is supported by a plurality of support members 181 provided on the ceiling surface of the processing vessel 100.

[0069] 6, a pressing member 190 that presses the center of the upper wafer WU is further provided on the upper surface of the upper chuck stage 180. The pressing member 190 has an actuator portion 191 and a cylinder portion 192.

[0070] The actuator unit 191 generates a constant pressure in a fixed direction by air supplied from an electropneumatic regulator (not shown), and can generate the pressure at a constant level regardless of the position of the point of application of the pressure. The actuator unit 191 contacts the center of the upper wafer WU by air from the electropneumatic regulator, and can control the pressing load applied to the center of the upper wafer WU. The tip of the actuator unit 191 is movable vertically through the through hole 176 by air from the electropneumatic regulator.

[0071] The actuator portion 191 is supported by a cylinder portion 192. The cylinder portion 192 can move the actuator portion 191 in the vertical direction by a drive portion having a built-in motor, for example.

[0072] As described above, the pressing member 190 controls the pressing load by the actuator portion 191, and controls the movement of the actuator portion 191 by the cylinder portion 192. Then, the pressing member 190 can abut and press the central portion of the upper wafer WU and the central portion of the lower wafer WL when bonding the wafers WU and WL, which will be described later.

[0073] <2-5. Configuration of the lower chuck> Next, the detailed configuration of the lower chuck 141 of the joining device 41 will be described.

[0074] As shown in Fig. 6, the lower chuck 141 employs a pin chuck system similar to the upper chuck 140. The lower chuck 141 has a main body 200 having a diameter equal to or larger than the diameter of the lower wafer WL in a plan view. A plurality of pins 201 that contact the back surface WL2 of the lower wafer WL are provided on the upper surface of the main body 200. In addition, an outer rib 202 that has the same height as the pins 201 and supports the outer periphery of the back surface WL2 of the lower wafer WL is provided on the outer periphery of the upper surface of the main body 200. The outer rib 202 is provided in a ring shape on the outside of the plurality of pins 201.

[0075] Further, on the upper surface of the main body 200, an inner rib 203 is provided inside the outer rib 202. The inner rib 203 has the same height as the pins 201 and supports the back surface WL2 of the lower wafer WL. The inner rib 203 is provided in an annular shape concentric with the outer rib 202. An inner region 204 (hereinafter sometimes referred to as the suction region 204) of the outer rib 202 is partitioned into a first suction region 204a inside the inner rib 203 and a second suction region 204b outside the inner rib 203.

[0076] A first suction port 205a for evacuating the lower wafer WL is formed in the first suction region 204a on the upper surface of the main body 200. The first suction port 205a is formed at one location in the first suction region 204a, for example. A first suction pipe 206a provided inside the main body 200 is connected to the first suction port 205a. Furthermore, a first vacuum pump 207a is connected to the first suction pipe 206a.

[0077] Further, a second suction port 205b for evacuating the lower wafer WL in the second suction region 204b is formed on the upper surface of the main body 200. The second suction port 205b is formed, for example, at two locations in the second suction region 204b. A second suction pipe 206b provided inside the main body 200 is connected to the second suction port 205b. Furthermore, a second vacuum pump 207b is connected to the second suction pipe 206b.

[0078] Then, suction regions 204a, 204b formed by being surrounded by the lower wafer WL, the main body 200, and the outer rib 202 are evacuated from suction ports 205a, 205b, respectively, to reduce the pressure in the suction regions 204a, 204b. At this time, since the atmosphere outside the suction regions 204a, 204b is at atmospheric pressure, the lower wafer WL is pushed toward the suction regions 204a, 204b by the atmospheric pressure by the reduced pressure, and the lower wafer WL is suctioned and held by the lower chuck 141. The lower chuck 141 is configured to be able to evacuate the lower wafer WL for each of the first suction region 204a and the second suction region 204b.

[0079] In the lower chuck 141, near the center of the main body 200, through holes (not shown) are formed in, for example, three places, penetrating the main body 200 in the thickness direction. And, lifting pins provided below the first lower chuck moving part 162 are adapted to be inserted into the through holes.

[0080] Guide members (not shown) are provided on the outer periphery of the main body 200 to prevent the wafers WU, WL, and overlapped wafer WT from jumping out or slipping off the lower chuck 141. The guide members are provided at multiple locations, for example, four locations, at equal intervals on the outer periphery of the main body 200.

[0081] The operation of each part of the bonding device 41 is controlled by the control unit 70 described above.

[0082] <3. Joining method> Next, a description will be given of a method for bonding the wafers WU and WL, which is performed using the bonding system 1 configured as above. Fig. 10 is a flow chart showing an example of main steps of such a wafer bonding process.

[0083] First, a cassette CU accommodating a plurality of upper wafers WU, a cassette CL accommodating a plurality of lower wafers WL, and an empty cassette CT are placed on a predetermined cassette mounting plate 11 in the load / unload station 2. Thereafter, the upper wafer WU in the cassette CU is removed by the wafer transfer device 22 and transferred to the transition device 50 in the third processing block G3 of the processing station 3.

[0084] Next, the upper wafer WU is transported by the wafer transport device 61 to the surface modification device 30 in the first processing block G1. In the surface modification device 30, the processing gas, oxygen gas or nitrogen gas, is excited to be turned into plasma and ionized in a predetermined reduced pressure atmosphere. The oxygen ions or nitrogen ions are irradiated onto the surface WU1 of the upper wafer WU, and the surface WU1 is subjected to plasma processing. Then, the surface WU1 of the upper wafer WU is modified (step S1 in FIG. 10).

[0085] Next, the upper wafer WU is transported by the wafer transport device 61 to the surface hydrophilization device 40 in the second processing block G2. In the surface hydrophilization device 40, pure water is supplied onto the upper wafer WU while rotating the upper wafer WU held by the spin chuck. The supplied pure water then diffuses onto the surface WU1 of the upper wafer WU, and hydroxyl groups (silanol groups) adhere to the surface WU1 of the upper wafer WU modified in the surface modification device 30, thereby making the surface WU1 hydrophilic. The surface WU1 of the upper wafer WU is also cleaned by the pure water (step S2 in FIG. 10).

[0086] Next, the upper wafer WU is transferred to the bonding device 41 in the second processing block G2 by the wafer transfer device 61. The upper wafer WU carried into the bonding device 41 is transferred to the position adjustment mechanism 120 by the wafer transfer mechanism 111 via the transition 110. Then, the horizontal orientation of the upper wafer WU is adjusted by the position adjustment mechanism 120 (step S3 in FIG. 10).

[0087] Thereafter, the upper wafer WU is transferred from the position adjustment mechanism 120 to the holding arm 131 of the inversion mechanism 130. Next, in the transfer region T1, the holding arm 131 is inverted to invert the front and back surfaces of the upper wafer WU (step S4 in FIG. 10). That is, the front surface WU1 of the upper wafer WU is faced downward.

[0088] Thereafter, the holding arm 131 of the inversion mechanism 130 rotates around the drive unit 133 and moves to below the upper chuck 140. Then, the upper wafer WU is delivered from the inversion mechanism 130 to the upper chuck 140. The upper wafer WU has its back surface WU2 adsorbed and held by the upper chuck 140 (step S5 in FIG. 10). Specifically, the vacuum pumps 172b, 173b, and 174b are operated to suction the upper wafer WU by the suction units 172, 173, and 174, and the upper wafer WU is adsorbed and held by the upper chuck 140.

[0089] While the upper wafer WU is being processed in the above-mentioned steps S1 to S5, the lower wafer WL is processed following the upper wafer WU. First, the lower wafer WL is removed from the cassette CL by the wafer transfer device 22 and transferred to the transition device 50 of the processing station 3.

[0090] Next, the lower wafer WL is transferred by the wafer transfer device 61 to the surface modification device 30, where the surface WL1 of the lower wafer WL is modified (step S6 in FIG. 10). Note that the modification of the surface WL1 of the lower wafer WL in step S6 is similar to the above-mentioned step S1.

[0091] Thereafter, the lower wafer WL is transferred by the wafer transfer device 61 to the surface hydrophilization device 40, where the surface WL1 of the lower wafer WL is hydrophilized and cleaned (step S7 in FIG. 10). Note that the hydrophilization and cleaning of the surface WL1 of the lower wafer WL in step S7 are similar to those in step S2 described above.

[0092] Thereafter, the lower wafer WL is transported to the bonding apparatus 41 by the wafer transport device 61. The lower wafer WL carried into the bonding apparatus 41 is transported to the position adjustment mechanism 120 by the wafer transport mechanism 111 via the transition 110. Then, the horizontal orientation of the lower wafer WL is adjusted by the position adjustment mechanism 120 (step S8 in FIG. 10).

[0093] Thereafter, the lower wafer WL is transported by the wafer transport mechanism 111 to the lower chuck 141, and its back surface WL2 is suction-held by the lower chuck 141 (step S9 in FIG. 10). Specifically, the vacuum pumps 207a and 207b are operated to suction the lower wafer WL through the suction ports 205a and 205b in the suction regions 204a and 204b, and the lower wafer WL is suction-held by the lower chuck 141.

[0094] Next, the horizontal positions of the upper wafer WU held by the upper chuck 140 and the lower wafer WL held by the lower chuck 141 are adjusted. Specifically, the lower chuck 141 is moved in the horizontal direction (X direction and Y direction) by the first lower chuck moving part 162 and the second lower chuck moving part 165, and predetermined reference points on the surface WL1 of the lower wafer WL are sequentially imaged by the upper imaging part 151. At the same time, predetermined reference points on the surface WU1 of the upper wafer WU are sequentially imaged by the lower imaging part 161. The imaged images are output to the control part 70. Based on the images imaged by the upper imaging part 151 and the images imaged by the lower imaging part 161, the control part 70 moves the lower chuck 141 by the first lower chuck moving part 162 and the second lower chuck moving part 165 to a position where the reference points of the upper wafer WU and the reference points of the lower wafer WL coincide with each other. In this manner, the horizontal positions of the upper wafer WU and the lower wafer WL are adjusted (Step S10 in FIG. 10).

[0095] In step S10, the lower chuck 141 is moved in the horizontal direction as described above, and the lower chuck 141 is rotated by the first lower chuck moving part 162 to adjust the rotational position of the lower chuck 141 (the orientation of the lower chuck 141).

[0096] Thereafter, the lower chuck 141 is moved vertically upward by the first lower chuck moving part 162 to adjust the vertical positions of the upper chuck 140 and the lower chuck 141, and the vertical positions of the upper wafer WU held by the upper chuck 140 and the lower wafer WL held by the lower chuck 141 are adjusted (step S11 in FIG. 10). The distance between the surface WU1 of the lower wafer WU and the surface WU1 of the upper wafer WU is adjusted to a predetermined distance, for example, 50 μm to 200 μm. Then, the upper wafer WU and the lower wafer WL are disposed opposite each other at predetermined positions, as shown in FIG. 11.

[0097] Next, a bonding process is performed on the upper wafer WU held by the upper chuck 140 and the lower wafer WL held by the lower chuck 141.

[0098] In this embodiment, a case will be described in which the suction timing of the second suction unit 173 is set in advance so that the bonding wave becomes uniform as described above. That is, for example, the sensor 175 detects the expansion of the bonding region A for the upper wafer WU of the previous lot, and based on the detection result, the suction timing of the second suction unit 173 for the upper wafer WU of the current lot is set.

[0099] First, as shown in Fig. 12, the actuator part 191 is lowered by the cylinder part 192 of the pressing member 190. Then, as the actuator part 191 is lowered, the center part of the upper wafer WU is pressed and lowered. At this time, a predetermined pressing load is applied to the actuator part 191 by air supplied from an electropneumatic regulator. Then, the pressing member 190 brings the center part of the upper wafer WU and the center part of the lower wafer WL into contact with each other and presses them (step S13 in Fig. 10).

[0100] In step S13, the operation of the first vacuum pump 172b is stopped to stop the vacuum pumping of the upper wafer WU from the first suction section 172, while the second vacuum pump 173b and the third vacuum pump 174b are left operating to vacuum the upper wafer WU by the second suction section 173 and the third suction section 174.

[0101] When the center of the upper wafer WU and the center of the lower wafer WL are pressed against each other, bonding between the centers begins. That is, since the surface WU1 of the upper wafer WU and the surface WL1 of the lower wafer WL have been modified in steps S1 and S6, respectively, van der Waals forces (intermolecular forces) are first generated between the surfaces WU1 and WL1, and the surfaces WU1 and WL1 are bonded to each other. Furthermore, since the surface WU1 of the upper wafer WU and the surface WL1 of the lower wafer WL have been hydrophilized in steps S2 and S7, respectively, the hydrophilic groups between the surfaces WU1 and WL1 are hydrogen-bonded (intermolecular forces), and the surfaces WU1 and WL1 are firmly bonded to each other. In this way, the bonding region A is formed.

[0102] Thereafter, a bonding wave is generated between the upper wafer WU and the lower wafer WU, in which a bonding region A expands from the center of the upper wafer WU and the lower wafer WU toward the outer periphery thereof.

[0103] 13, while the pressing member 190 is pressing the center of the upper wafer WU and the center of the lower wafer WL, the operation of the second vacuum pump 173b is stopped to stop the vacuum pumping of the upper wafer WU from the second suction unit 173. At this time, the suction timing of the eight second suction units 173 is made different as described above. That is, the timing at which the second suction unit 173 in the 45° direction releases the upper wafer WU is delayed, and the timing at which the second suction unit 173 in the 90° direction releases the upper wafer WU is advanced. This makes it possible to make the timing at which the bonding region A arrives at the positions of the eight sensors 175 almost the same, and to make the bonding wave uniform.

[0104] 14, the operation of the third vacuum pump 174b is stopped to stop the vacuum pumping of the upper wafer WU from the third suction unit 174. Then, the upper wafer WU is dropped onto the lower wafer WL in sequence and comes into contact with it, and the bonding between the surfaces WU1 and WL1 by the van der Waals force and hydrogen bonds described above spreads in sequence. Thus, the surface WU1 of the upper wafer WU and the surface WL1 of the lower wafer WL come into contact with each other over their entire surfaces, and the upper wafer WU and the lower wafer WL are bonded together (step S14 in FIG. 10). At this time, since the bonding wave is uniform, it is possible to suppress distortion of the bonded overlapped wafers WT.

[0105] In step S14, the bonding region A is detected using eight sensors 175 to monitor the bonding wave and inspect the bonding state of the upper wafer WU and the lower wafer WL. As described above, in this embodiment, the suction timing of the second suction unit 173 is set in advance to make the bonding wave uniform, but the bonding wave may become non-uniform due to various disturbances. In such a case, a warning is issued to improve the product yield. Furthermore, when the bonding wave becomes non-uniform in this way, the suction timing of the second suction unit 173 is corrected based on the detection result of the sensors 175 when bonding the succeeding upper wafer WU and lower wafer WL.

[0106] 15, the actuator portion 191 of the pushing member 190 is raised to the upper chuck 140. In addition, the operation of the vacuum pumps 207a and 207b is stopped to stop the evacuation of the lower wafer WL in the suction region 204, and the suction and holding of the lower wafer WL by the lower chuck 141 is stopped.

[0107] The overlapped wafer WT in which the upper wafer WU and the lower wafer WL are bonded together is transferred by the wafer transfer device 61 to the transition device 51, and then transferred by the wafer transfer device 22 of the carry-in / out station 2 to a cassette CT on a predetermined cassette mounting plate 11. In this manner, a series of bonding processes for the wafers WU and WL is completed.

[0108] According to the embodiment described above, the sensor 175 can detect the release of the upper wafer WU held by the upper chuck 140 from the upper chuck 140, and can grasp the bonding wave. Then, the control unit 70 controls the suction timing of the second suction unit 173 based on the detection result of the sensor 175. This can make the bonding wave uniform, and suppress distortion of the overlapped wafer WT.

[0109] In addition, since the bonding system 1 of the present embodiment includes the surface modification device 30, the surface hydrophilization device 40, and the bonding device 41, the bonding of the wafers WU and WL can be efficiently performed within one system, and therefore the throughput of the wafer bonding process can be improved.

[0110] <4. Other embodiments> Next, another embodiment of the present invention will be described.

[0111] In the upper chuck 140 of the above embodiment, the sensors 175 are arranged between the first suction portion 172 and the second suction portion 173, concentrically arranged with the main body portion 170 and spaced apart from each other at a predetermined interval, but the arrangement of the sensors 175 is not limited to this.

[0112] 16, in addition to being located between the first suction portion 172 and the second suction portion 173, a plurality of sensors 175, for example, eight sensors, may be arranged at predetermined intervals in the circumferential direction on a concentric circle with the main body portion 170 on the inner circumferential side of the main body portion 170 relative to the second suction portion 173. That is, the two sensors 175, the center of the first suction portion 172, and the center of the second suction portion 173 are arranged on the same center line of the main body portion 170. In the following, the sensor 175 between the first suction portion 172 and the second suction portion 173 is referred to as sensor 175a, and the sensor 175 on the inner circumferential side of the second suction portion 173 is referred to as sensor 175b.

[0113] In this case, the suction timing of the second suction part 173 on the same center line as the sensor 175b can be controlled based on the detection result of the sensor 175b. Therefore, the second suction part 173 can be feedforward controlled in real time, and the bonding wave can be made more reliably uniform.

[0114] It is also possible to omit the sensor 175a and provide only the sensor 175b. However, since the sensor 175a is disposed away from the center of the main body 170, it is possible to more clearly grasp the non-uniform diffusion in the bonding region A than the sensor 175b. Specifically, for example, when the diameter of the upper wafer WU is 300 mm, the sensor 175a is preferably disposed outside the center of the main body 170 by a diameter of 240 mm.

[0115] 8, the conventional bonding area A expands into a substantially rectangular shape. Considering the symmetry of the expansion of the bonding area A, it is possible to reduce the number of sensors 175.

[0116] 17(a)-(b), for example, two sensors 175 may be arranged on the same circumference of the main body 170. That is, at least one sensor 175 may be arranged in each of the 45° direction and the 90° direction. In this case, the sensor 175 in the 45° direction can be used to estimate the expansion of the bonding area A in the other 45° direction, and the sensor 175 in the 90° direction can be used to estimate the expansion of the bonding area A in the other 90° direction.

[0117] However, when the sensor 175 is provided all around the circumference of the main body 170 as shown in FIG. 7, it is possible to grasp even the size of the gap between the upper wafer WU and the lower wafer WL. Here, the upper wafer WU and the lower wafer WL are not strictly parallel, and may be tilted by a minute distance, for example, a few μm. In such a case, the larger the gap between the upper wafer WU and the lower wafer WL, the easier it is for air to escape to the outside, and the bonding area A expands quickly. Even if there is a difference in the expansion of the bonding area A, when the sensor 175 is provided all around the circumference of the main body 170, it is possible to appropriately grasp the bonding wave.

[0118] In the above embodiment, the sensor 175 is used to detect the contact state between the upper wafer WU and the lower wafer WL and grasp the bonding wave, but the bonding wave may also be grasped by measuring the displacement of the actuator part 191. As shown in Fig. 19, the pressing member 190 is provided with a laser displacement meter 300. The laser displacement meter 300 measures the displacement of a target 301 provided on the actuator part 191 to measure the displacement of the actuator part 191.

[0119] In such a case, in step S13 (FIG. 12) of the above embodiment, when the actuator part 191 of the pressing member 190 is lowered, the displacement of the actuator part 191 is measured by the laser displacement meter 300. Then, when the displacement measured by this laser displacement meter 300 reaches a predetermined threshold value, it is detected that the center part of the upper wafer WU and the center part of the lower wafer WL have come into contact with each other.

[0120] In this way, the start of the bonding region A can be grasped based on the measurement result by the laser displacement meter 300, so that the bonding wave can be grasped more appropriately. Also, based on the measurement result by the laser displacement meter 300, it becomes possible to control the suction timing of the suction parts 172 to 174.

[0121] The displacement meter provided on the pushing member 190 is not limited to the laser displacement meter 300, and any type can be selected as long as it can measure the displacement of the actuator portion 191.

[0122] In the upper chuck 140 according to the above embodiment, the eight second suction parts 173 are connected to individual second vacuum pumps 173b, but one second vacuum pump 173b may collectively control the operations of the multiple second suction parts 173. For example, four second suction parts 173 located in 45° directions may be controlled by one second vacuum pump 173b. Also, four second suction parts 173 located in 90° directions may be controlled by one second vacuum pump 173b.

[0123] Similarly, for the eight first suction parts 172, one first vacuum pump 172b may collectively control the operations of the multiple first suction parts 172.

[0124] Moreover, the number and arrangement of suction units 172 to 174 are not limited to the example shown in Fig. 7. The number of suction units on the same circumference in main body unit 170 may be other than eight. Moreover, in main body unit 170, three or more suction units may be provided.

[0125] In the joining device 41 of the above embodiment, the lower chuck 141 is configured to be movable in the horizontal direction, but the upper chuck 140 may be configured to be movable in the horizontal direction, or both the upper chuck 140 and the lower chuck 141 may be configured to be movable in the horizontal direction.

[0126] In addition, in the joining device 41 of the above embodiment, the lower chuck 141 is configured to be movable in the vertical direction, but the upper chuck 140 may be configured to be movable in the vertical direction, or both the upper chuck 140 and the lower chuck 141 may be configured to be movable in the vertical direction.

[0127] Furthermore, in the joining device 41 of the above embodiment, the lower chuck 141 is configured to be rotatable, but the upper chuck 140 may be configured to be rotatable, or both the upper chuck 140 and the lower chuck 141 may be configured to be rotatable.

[0128] In the bonding system 1 according to the above embodiment, after the wafers WU and WL are bonded by the bonding apparatus 41, the bonded overlapped wafer WT may be further heated (annealed) at a predetermined temperature. By subjecting the overlapped wafer WT to such a heating treatment, the bonding interface can be bonded more firmly.

[0129] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person skilled in the art can conceive of various modified or altered examples within the scope of the ideas described in the claims, and it is understood that such examples also naturally fall within the technical scope of the present invention. The present invention is not limited to this example, and can take various forms. The present invention can also be applied to cases where the substrate is other substrates such as FPDs (flat panel displays) other than wafers, mask reticles for photomasks, etc. [Explanation of symbols]

[0130] 1 Joining System 2 Loading / unloading station 3 Processing Station 30 Surface modification equipment 40 Surface hydrophilization device 41 Joining equipment 61 Wafer transport device 70 Control section 140 Upper chuck 141 Lower chuck 172 First suction part 173 Second suction part 174 Third suction part 175 Sensors 190 Pushing member 300 Laser Displacement Meter WU Upper Wafer WL Lower wafer WT Polymer Wafer

Claims

[Claim 1] A bonding apparatus for bonding substrates, comprising: a first holding portion that holds the first substrate by suction on a lower surface of the first substrate; a second holding part provided below the first holding part and configured to suction-hold a second substrate on an upper surface of the second holding part; a pressing member provided in the first holding portion and configured to press a center portion of the first substrate; a substrate detection unit provided in the first holding unit and configured to detect a contact state between the first substrate and the second substrate; The bonding apparatus according to claim 1, wherein the substrate detection unit measures a flow rate or a pressure of a gas flowing through a suction pipe for evacuating the first substrate.

Images