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

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] The present invention relates to a bonding apparatus for bonding substrates together. , a joining system including the joining device, a joining method using the joining device, a program, and a computer storage medium Regarding.

[0003] Therefore, the use of 3D integration technology for stacking semiconductor devices in three dimensions has been proposed. In this 3D integration technology, two semiconductor wafers (hereinafter referred to as "wafers") are bonded using a bonding system, such as that described in Patent Document 1. For example, the bonding system includes a surface modification device that modifies the surfaces of the wafers to be bonded, a surface hydrophilization device that hydrophilizes the surfaces of the wafers modified by the surface modification device, and a bonding device that bonds 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 wafer surfaces to modify the surfaces, and the surface hydrophilization device supplies pure water to the wafer surfaces to hydrophilize them. After that, the wafers are bonded to each other in the bonding device using 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 the "upper wafer") on its lower surface, a lower chuck that is provided below the upper chuck and holds another wafer (hereinafter referred to as the "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 centers of the upper and lower wafers together, bonding the centers together 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 toward the outer periphery. The upper and lower wafers are then bonded. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-039364 Summary of the Invention [Problem to be solved by the invention]

[0006] To minimize distortion of the bonded overlapped wafers, it is preferable for the bonding wave to expand evenly, i.e., concentrically, from the center to the periphery of the wafer. However, the bonding apparatus described in Patent Document 1 does not monitor the bonding wave, and therefore cannot detect uneven expansion of the bonding wave. Therefore, there is room for improvement in conventional wafer bonding processes.

[0007] The present invention has been made in view of the above points, and has as its 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 object, the present invention provides a bonding device for bonding substrates together, comprising: a first holding section that sucks and holds a first substrate on its underside; a second holding section that is provided below the first holding section and sucks and holds a second substrate on its upper surface; a pressing member that is provided on the first holding section and has an actuator section that comes into contact with the center of the first substrate and is movable up and down, and presses the center of the first substrate; a substrate detection section that is provided on the first holding section and detects a contact state between the first substrate and the second substrate; and a displacement meter that measures a displacement of the actuator section. The substrate detection units are arranged concentrically with the first holding unit, and the substrate detection units are capacitance sensors or distance measurement sensors. It is characterized by the following.

[0009] According to the present invention, the substrate detection unit can detect when a first substrate held by a first holder is released from the first holder. When this release of the first substrate occurs, the first substrate falls onto and contacts the second substrate, and the first and second substrates are bonded together by intermolecular forces. Therefore, by detecting the release 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. [Effects 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 carried out appropriately. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view showing an outline of the configuration of a joining system according to an embodiment of the present invention; [Figure 2] 1 is a side view showing an outline of the internal configuration of a joining system according to an embodiment of the present invention. [Figure 3] FIG. 2 is a side view showing an outline of the configuration of the upper wafer and the lower wafer. [Figure 4] FIG. 2 is a cross-sectional view showing an outline of the configuration of a joining device. [Figure 5] FIG. 2 is a longitudinal sectional view showing an outline of the configuration of a joining device. [Figure 6] FIG. 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. [Figure 7] FIG. 2 is a plan view of the upper chuck as seen from below. [Figure 8] FIG. 10 is an explanatory diagram showing the expansion of a bonding area between wafers in a conventional method. [Figure 9]10 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. 10 is an explanatory diagram showing a state in which an upper wafer and a lower wafer are arranged opposite each other. [Figure 12] 10 is an explanatory diagram showing a state in which the center of the upper wafer and the center of the lower wafer are pressed against each other to bring them into contact with each other. FIG. [Figure 13] 10 is an explanatory diagram showing how the bonding between the upper wafer and the lower wafer is diffused from the center to the outer periphery. FIG. [Figure 14] FIG. 10 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. 10 is an explanatory diagram showing a state in which the upper wafer and the lower wafer are bonded together. [Figure 16] FIG. 10 is a plan view of an upper chuck showing the arrangement of sensors according to another embodiment. [Figure 17] FIG. 10 is a plan view of an upper chuck showing the arrangement of sensors according to another embodiment. [Figure 18] FIG. 10 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 according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0013] <1. Configuration of the joining system> First, a description will be given of the configuration of the bonding system according to this embodiment. Fig. 1 is a plan view showing an outline of the configuration of the bonding system 1. Fig. 2 is a side view showing an outline of the internal configuration of the bonding 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 upper wafer will be referred to as the "upper wafer WU" as the first substrate, and the lower wafer will be referred to as the "lower wafer WL" as the second substrate. The bonding surface to which the upper wafer WU is bonded will be referred to as the "front surface WU1," and the surface opposite the front surface WU1 will be referred to as the "back surface WU2." Similarly, the bonding surface to which the lower wafer WL is bonded will be referred to as the "front surface WL1," and the surface opposite the front surface WL1 will be 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, each capable of accommodating a plurality of wafers WU, WL, and a plurality of overlapping wafers WT, 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 mounting table 10. The cassette mounting table 10 is provided with a plurality of, for example, four, cassette mounting plates 11. The cassette mounting 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 mounting plates 11 when they are carried in or out of the bonding system 1. In this manner, the carry-in / out station 2 is configured to hold a plurality of upper wafers WU, a plurality of lower wafers WL, and a plurality of overlapped wafers WT. Note that the number of cassette mounting plates 11 is not limited to this embodiment and can be set arbitrarily. Furthermore, one of the cassettes may be used for recovering abnormal wafers. In other words, this cassette 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 the other normal overlapped wafers WT. In this embodiment, one cassette CT out of the plurality of cassettes CT is used to collect abnormal wafers, and the other cassettes CT are used to store normal overlapped wafers WT.

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

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

[0019] For example, the first processing block G1 is provided with a surface modification device 30 that modifies the surfaces WU1 and WL1 of the wafers WU and WL. In the surface modification device 30, for example, in a reduced pressure atmosphere, oxygen gas or nitrogen gas serving as a processing gas is excited to form plasma and ionized. These oxygen ions or nitrogen ions are irradiated onto the surfaces WU1 and WL1, and the surfaces WU1 and 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 side of the load / unload station 2. 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 the wafers WU, WL are rotated, for example, while being held by a spin chuck. Then, the supplied pure water spreads 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 wafers WU and WL and overlapping 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 to third processing blocks G1 to G3 forms 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, vertically, horizontally (Y-direction, X-direction), and around a 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. 1. 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 drive systems for the various processing devices and transport devices described above to realize the wafer bonding process described below in the bonding system 1. The program may be recorded on a computer-readable storage medium H, such as a computer-readable hard disk (HD), flexible disk (FD), compact disk (CD), magnetic optical disk (MO), or memory card, and installed into the control unit 70 from the storage medium H.

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

[0027] <2-1. Overall configuration of the joining device> 4 and 5, the bonding apparatus 41 has a processing vessel 100 whose interior can be sealed. 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 interior 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 the side surface of the processing vessel 100 in the transfer region T1. In addition, loading / unloading ports 104 for the wafers WU, WL, and overlapping wafer WT are also formed in the inner wall 103.

[0029] A transition 110 is provided on the positive Y-direction side of the transfer region T1 for temporarily placing the wafers WU, WL, and overlapping wafer WT. 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 on the transition 110 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, horizontal directions (X direction and Y direction), and around a vertical axis. The wafer transfer mechanism 111 can transfer wafers WU, WL, and overlapping wafers WT within the transfer region T1 or between the transfer region T1 and the processing region T2.

[0031] A position adjustment mechanism 120 that adjusts the horizontal orientations of the wafers WU and WL is provided on the negative Y-direction side of the transfer region T1. The position adjustment mechanism 120 includes a base 121 equipped with a holder (not shown) that holds and rotates the wafers WU and WL, and a detector 122 that detects 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 using the detector 122, thereby adjusting the positions of the notches and thereby adjusting the horizontal orientations of the wafers WU and WL. The structure that holds 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] The transfer region T1 is also provided with an inversion mechanism 130 that inverts the upper wafer WU upside down. 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). The holding arm 131 is also 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 equipped with, for example, a motor. The drive unit 133 allows the holding arm 131 to rotate about a horizontal axis. The holding arm 131 is also rotatable about the drive unit 133 and movable in the horizontal direction (X direction). Another drive unit (not shown) equipped with, for example, a motor is provided below the drive unit 133. This other drive unit allows the drive unit 133 to move vertically along a support column 134 extending vertically. In this way, the drive unit 133 allows the upper wafer WU held by the holding member 132 to rotate about a horizontal axis and move vertically and horizontally. The upper wafer WU held by the holding member 132 can also rotate about the drive unit 133 and move between the position adjustment mechanism 120 and an upper chuck 140 (described later).

[0034] The processing region T2 is provided with an upper chuck 140 as a first holding unit that suction-holds the upper wafer WU on its lower surface, and a lower chuck 141 as a second holding unit that places the lower wafer WL on its upper surface and holds it by suction. The lower chuck 141 is provided below the upper chuck 140 and is configured 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 opposite each other.

[0035] The upper chuck 140 is held by an upper chuck holder 150 provided above the upper chuck 140. The upper chuck holder 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 holder 150.

[0036] The upper chuck holding part 150 is provided with an upper imaging part 151 that 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 is, 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 captures an image of the front surface WU1 of the upper wafer WU held on 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 will be described later. In addition, the first lower chuck moving part 162 is configured to be able to move the lower chuck 141 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 is attached to a pair of rails 164, 164 extending in the horizontal direction (X direction). The support table 163 is configured to be 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 are 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, i.e., 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 are 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] 6 and 7, the upper chuck 140 employs a pin chuck system. 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] Furthermore, a plurality of suction parts 172 to 174 that suck the upper wafer WU by vacuuming 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 pins 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 first suction portions 172, for example, 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 units 172. The eight first suction units 172 can individually suck the upper wafer WU by vacuuming using the first vacuum pump 172b.

[0046] Similar to the first suction portion 172, the second suction portion 173 has an arc shape in a plan view. A plurality of second suction portions 173, for example, eight second suction portions 173, are arranged circumferentially at predetermined intervals on a concentric circle with the main body portion 170, closer to the inner periphery of the main body portion 170 than the first suction portion 172. 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 periphery 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 suck the upper wafer WU by vacuuming with the third vacuum pump 174b.

[0049] The main body 170 is provided with a sensor 175 as a substrate detection unit that detects separation of the upper wafer WU from the main body 170. A plurality of sensors 175, for example, eight sensors 175, are arranged circumferentially at predetermined intervals 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 that is held by suction on the upper chuck 140. The through-hole 176 is adapted to receive the tip of an actuator portion 191 of a pressing member 190, which will be described later.

[0051] <2-3. Details of the upper chuck sensor> Next, the 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 will be described later, 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, forming a bonded region at the centers of both wafers. After that, a bonding wave is generated that expands the bonded region from the centers of both wafers WU and WL toward their outer peripheries, and the surfaces WU1 and WL1 of the upper wafer WU and the lower wafer WL are bonded together over their entire surfaces.

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

[0054] Various sensors can be used for the sensor 175. For example, a reflective fiber sensor may be used for the sensor 175. In such a 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. By measuring the amount of received reflected light, the orthogonality between the optical axis and the upper wafer WU can be determined. That is, when the amount of reflected light is small, the orthogonality between the optical axis and the upper wafer WU is large (the upper wafer WU is tilted large), meaning 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 upper wafer WU is tilted small), meaning 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 detachment state of the upper wafer WU from the upper chuck 140) can be detected, and the bonding wave can be grasped.

[0055] Furthermore, 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 toward 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 the bonding wave can be grasped.

[0056] Alternatively, 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, i.e., at the position indicated by reference numeral "175" in FIGS. 6 and 7, and the sensor 175 is provided on a suction pipe (not shown) connected to the suction pad. Note that the suction pad is not intended to suction and hold the upper wafer WU, but rather to evacuate the upper wafer WU at a minute pressure, for example, approximately -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 pipe. For example, when the upper wafer WU is released from the upper chuck 140, the gas flow in the suction pipe changes, causing changes in the gas flow rate and pressure. The sensor 175 measures the change in the air flow in the suction pipe to detect the release of the upper wafer WU from the upper chuck 140 (in other words, the contact state between the upper wafer WU and the lower wafer WL) and thereby detect the bonding wave. The sensor 175 may be provided in the first suction tube 172a of the first suction part 172 and the second suction tube 173a of the second suction part 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 location of the sensor 175 is determined depending on 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 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. Note that FIG. 8 is a plan view of the upper wafer WU held by the upper chuck 140, viewed from below.

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

[0100] crystal orientation perpendicular to the surface WU1. The notch 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 more rapidly in directions with a 45-degree period (45°, 135°, 225°, and 315° directions shown in FIG. 8 , hereinafter referred to as the 45° direction) based on the 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 directions with a 90-degree period (directions of 0°, 90°, 180°, and 270° shown in FIG. 8 , hereinafter referred to as the 90° direction) based on the 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 joining area A, which was circular at the start of joining (when the center is joined), 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 region 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 represents the elapsed time of the bonding process, and the vertical axis represents 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 close to the upper chuck 140), this 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 far from the upper chuck 140), this indicates that the upper wafer WU is away from the upper chuck 140 at the position of the sensor 175 and in contact with the lower wafer WL, and the bonding region A has arrived.

[0063] 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 arrival of the bonding area A in the 45° direction and the arrival of the bonding area A 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 value 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 value of ΔT is set based on the allowable range of 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 the eight sensors 175 almost the same. Therefore, the expansion of the bonding region A can be made uniform, and the bonding wave can be made uniform (in a shape close to concentric circles).

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

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

[0068] 5, the upper chuck holder 150 has an upper chuck stage 180 provided on the upper surface of the main body 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 170 in a plan view, and is fixed to the main body 170 by, for example, screws. 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 part 191 and a cylinder part 192.

[0070] The actuator unit 191 generates a constant pressure in a fixed direction using air supplied from an electropneumatic regulator (not shown), and can generate the pressure at a constant level regardless of the position of the pressure application point. The air from the electropneumatic regulator allows the actuator unit 191 to abut against the center of the upper wafer WU and control the pressure load applied to the center of the upper wafer WU. The tip of the actuator unit 191 is inserted through the through-hole 176 and can be raised and lowered vertically using the air from the electropneumatic regulator.

[0071] The actuator part 191 is supported by a cylinder part 192. The cylinder part 192 can move the actuator part 191 in the vertical direction by a drive part 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, when bonding the wafers WU and WL as described below, the pressing member 190 can abut and press the center of the upper wafer WU and the center of the lower wafer WL.

[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 come into contact with 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 around the outer periphery of the plurality of pins 201.

[0075] Furthermore, an inner rib 203 is provided on the upper surface of the main body 200, inside the outer rib 202, and has the same height as the pins 201. The inner rib 203 supports the back surface WL2 of the lower wafer WL. The inner rib 203 is provided in a ring shape concentric with the outer rib 202. An inner region 204 of the outer rib 202 (hereinafter sometimes referred to as the suction region 204) is divided 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, for example, at one location in the first suction region 204a. 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, second suction ports 205b for evacuating the lower wafer WL are formed in the second suction region 204b on the upper surface of the main body 200. The second suction ports 205b are 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 and 204b formed by the lower wafer WL, the main body 200, and the outer rib 202 are evacuated through suction ports 205a and 205b, respectively, to reduce the pressure in the suction regions 204a and 204b. At this time, because the atmosphere outside the suction regions 204a and 204b is atmospheric pressure, the lower wafer WL is pressed toward the suction regions 204a and 204b by the atmospheric pressure by the reduced pressure, and the lower wafer WL is suction-held by the lower chuck 141. The lower chuck 141 is configured to be able to evacuate the lower wafer WL at 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 locations, penetrating the main body 200 in the thickness direction. 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 overlapping wafer WT from jumping out or sliding 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 joining device 41 is controlled by the control unit 70 described above.

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

[0083] First, a cassette CU containing a plurality of upper wafers WU, a cassette CL containing a plurality of lower wafers WL, and an empty cassette CT are placed on a predetermined cassette mounting plate 11 in the carry-in / out 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 transferred by the wafer transfer 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 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 transferred by the wafer transfer 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 the upper wafer WU held by the spin chuck is being rotated. The supplied pure water then diffuses over 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 hydrophilizing the surface WU1. The surface WU1 of the upper wafer WU is also cleaned with 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. After being transferred into the bonding device 41, the upper wafer WU 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 reversing mechanism 130. Subsequently, in the transfer region T1, the holding arm 131 is reversed to reverse 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 faces downward.

[0088] Thereafter, the holding arm 131 of the inversion mechanism 130 rotates around the drive unit 133 and moves below the upper chuck 140. Then, the upper wafer WU is transferred from the inversion mechanism 130 to the upper chuck 140. The back surface WU2 of the upper wafer WU is suction-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 suction-held by the upper chuck 140.

[0089] While the upper wafer WU is being processed through the above-described 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 in 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 the same as in step S1 described above.

[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 transferred to the bonding device 41 by the wafer transfer device 61. The lower wafer WL transferred 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 lower wafer WL is adjusted by the position adjustment mechanism 120 (step S8 in FIG. 10).

[0093] Thereafter, the lower wafer WL is transferred to the lower chuck 141 by the wafer transfer mechanism 111, 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 in the suction regions 204a and 204b through the suction ports 205a and 205b, 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 first lower chuck moving unit 162 and the second lower chuck moving unit 165 move the lower chuck 141 in the horizontal direction (X direction and Y direction), and the upper imaging unit 151 sequentially captures images of predetermined reference points on the surface WL1 of the lower wafer WL. At the same time, the lower imaging unit 161 sequentially captures images of predetermined reference points on the surface WU1 of the upper wafer WU. The captured images are output to the control unit 70. Based on the images captured by the upper imaging unit 151 and the lower imaging unit 161, the control unit 70 controls the first lower chuck moving unit 162 and the second lower chuck moving unit 165 to move the lower chuck 141 to a position where the reference points of the upper wafer WU and the lower wafer WL coincide with each other. In this way, 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 horizontally as described above, and the lower chuck 141 is rotated by the first lower chuck moving unit 162, so that the rotational position of the lower chuck 141 (the orientation of the lower chuck 141) is also adjusted.

[0096] Thereafter, the first lower chuck moving unit 162 moves the lower chuck 141 vertically upward to adjust the vertical positions of the upper chuck 140 and the lower chuck 141, and also adjust 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 (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, the upper wafer WU held by the upper chuck 140 and the lower wafer WL held by the lower chuck 141 are bonded together.

[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 the 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 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 at the second suction section 173 and the third suction section 174.

[0101] When the centers of the upper wafer WU and the lower wafer WL are brought into contact and pressed together, bonding begins between the centers. Specifically, because 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, bonding the surfaces WU1 and WL1 together. Furthermore, because 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 form hydrogen bonds (intermolecular forces), firmly bonding the surfaces WU1 and WL1 together. In this way, a bonding region A is formed.

[0102] Thereafter, a bonding wave is generated between the upper wafer WU and the lower wafer WU, with the bonding region A expanding 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, and the vacuum pumping of the upper wafer WU from the second suction unit 173 is stopped. At this time, as described above, the suction timing of the eight second suction units 173 is made different. That is, the timing at which the second suction unit 173 in the 45° direction releases the upper wafer WU is made slower, and the timing at which the second suction unit 173 in the 90° direction releases the upper wafer WU is made faster. This makes it possible to make the timing at which the bonding region A arrives at the positions of the eight sensors 175 approximately the same, thereby making the bonding wave uniform.

[0104] 14, the operation of the third vacuum pump 174b is stopped, and the evacuation of the upper wafer WU from the third suction unit 174 is stopped. Then, the upper wafer WU is successively dropped onto the lower wafer WL and abuts against it, and the bonding between the surfaces WU1 and WL1 due to the van der Waals forces and hydrogen bonds described above gradually spreads. Thus, the entire surfaces WU1 of the upper wafer WU and the surface WL1 of the lower wafer WL abut against each other, and the upper wafer WU and the lower wafer WL are bonded together (step S14 in FIG. 10). At this time, because the bonding wave is uniform, distortion of the bonded overlapped wafers WT can be suppressed.

[0105] In step S14, the bonding region A is detected using eight sensors 175, the bonding wave is monitored, and the bonding state of the upper wafer WU and the lower wafer WL is inspected. 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. However, various disturbances may cause the bonding wave to become non-uniform. In such cases, a warning is issued, thereby improving 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 results of the sensors 175 when bonding the subsequent 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, the vacuum pumping of the lower wafer WL in the suction region 204 is stopped, 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 way, the series of bonding processes for the wafers WU and WL is completed.

[0108] According to the above embodiment, the sensor 175 can detect when the upper wafer WU held by the upper chuck 140 is released from the upper chuck 140, and the bonding wave can be grasped. 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 makes it possible to make the bonding wave uniform and suppress distortion of the overlapped wafer WT.

[0109] Furthermore, since the bonding system 1 of this embodiment includes the surface modification device 30, the surface hydrophilization device 40, and the bonding device 41, the wafers WU and WL can be bonded efficiently within one system, thereby improving the throughput of the wafer bonding process.

[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, aligned circumferentially on a concentric circle with the main body portion 170 and spaced apart at a predetermined interval, but the arrangement of the sensors 175 is not limited to this.

[0112] 16 , in addition to being located between first suction portion 172 and second suction portion 173, a plurality of sensors 175 (e.g., eight sensors) may be arranged concentrically with main body portion 170 and at predetermined intervals in the circumferential direction, further on the inner circumferential side of second suction portion 173. That is, the two sensors 175, the center of first suction portion 172, and the center of second suction portion 173 are arranged on the same center line of main body portion 170. Note that, hereinafter, sensor 175 between first suction portion 172 and second suction portion 173 will be referred to as sensor 175a, and sensor 175 on the inner circumferential side of second suction portion 173 will be referred to as sensor 175b.

[0113] In this case, the suction timing of the second suction part 173, which is 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 can more clearly grasp the uneven 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 this 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 the 45° direction and one in 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 another 45° direction, and the sensor 175 in the 90° direction can be used to estimate the expansion of the bonding area A in another 90° direction.

[0117] However, if the sensors 175 are provided around the entire 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, but may be tilted by a small 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, if the sensors 175 are provided around the entire 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 section 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 section 191, and thereby measures the displacement of the actuator section 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, it is detected that the center of the upper wafer WU and the center 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 results of the laser displacement meter 300, and therefore the bonding wave can be grasped more appropriately. Also, based on the measurement results of the laser displacement meter 300, it becomes possible to control the suction timing of the suction units 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 units 173 are connected to individual second vacuum pumps 173b. However, one second vacuum pump 173b may collectively control the operation of multiple second suction units 173. For example, four second suction units 173 located at 45° angles may be controlled by one second vacuum pump 173b. Alternatively, four second suction units 173 located at 90° angles may be controlled by one second vacuum pump 173b.

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

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

[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] Furthermore, 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 in 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 heat treatment, the bonding interface can be bonded more firmly.

[0129] Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It will be apparent to those skilled in the art that various modifications and alterations can be made within the scope of the concepts set forth in the claims, and it will be understood that such modifications and alterations naturally fall within the technical scope of the present invention. The present invention is not limited to these examples and can take on various forms. The present invention can also be applied to substrates other than wafers, such as FPDs (flat panel displays) and mask reticles for photomasks. [Explanation of symbols]

[0130] 1. Joint System 2 Loading / unloading station 3 Processing Stations 30 Surface modification equipment 40 Surface hydrophilization device 41 Joining equipment 61 Wafer transport device 70 Control Unit 140 Upper chuck 141 Lower zipper 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 polymerized wafer

Claims

1. A bonding apparatus for bonding substrates together, a first holding unit that suction-holds the first substrate on a lower surface thereof; a second holding portion provided below the first holding portion and configured to suction-hold a second substrate on an upper surface thereof; a pressing member provided in the first holding portion, the pressing member having an actuator portion that is in contact with a center portion of the first substrate and can be raised and lowered, and that presses the 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; a displacement meter for measuring the displacement of the actuator unit, a plurality of the substrate detection units are arranged concentrically with the first holding unit; The bonding apparatus is characterized in that the substrate detection unit is a capacitance sensor or a distance measurement sensor.

2. A bonding device as described in claim 1, characterized in that it has a control unit that detects that the center of the first substrate and the center of the second substrate have come into contact when the displacement measured by the displacement meter reaches a threshold value, and thereby determines the start of the bonding area between the first substrate and the second substrate.

3. The first holding unit has a plurality of suction units that vacuum-suck and adsorb the first substrate, 3. The welding apparatus according to claim 1, further comprising a control unit that controls a suction timing of the suction unit based on a measurement result of the displacement meter.

4. A joining device described in any one of claims 1 to 3, characterized in that the displacement meter measures the displacement of a target provided on the actuator unit to measure the displacement of the actuator unit.

5. A joining system comprising the joining device according to any one of claims 1 to 4, a processing station equipped with the joining device; a loading / unloading station that holds a plurality of the first substrates, the second substrates, or laminated substrates in which the first substrate and the second substrate are bonded, and that loads / unloads the first substrates, the second substrates, or the laminated substrates into / from the processing station; The processing station comprises: a surface modification device that modifies the surface to be bonded of the first substrate or the second substrate; a surface hydrophilization device that hydrophilizes the surface of the first substrate or the second substrate modified by the surface modification device; a transport device for transporting the first substrate, the second substrate, or the laminated substrate to the surface modification device, the surface hydrophilization device, and the bonding device, A bonding system, characterized in that the bonding apparatus bonds the first substrate and the second substrate whose surfaces have been hydrophilized by the surface hydrophilization apparatus.

6. A bonding method for bonding substrates, comprising the steps of: a positioning step of positioning the first substrate held on the lower surface of the first holding part and the second substrate held on the upper surface of the second holding part so as to face each other; a pressing step of lowering an actuator part of a pressing member provided on the first holding part and pressing the central part of the first substrate, and causing the pressing member to press the central part of the first substrate and the central part of the second substrate to come into contact with each other; thereafter, a bonding step of sequentially bonding the first substrate and the second substrate from the center toward the outer periphery of the first substrate while the center of the first substrate and the center of the second substrate are in contact with each other, In the pressing step, a displacement of the actuator unit is measured by a displacement meter, and when the displacement measured by the displacement meter reaches a threshold value, abutment between the center of the first substrate and the center of the second substrate is detected, thereby grasping the start of a bonding region between the first substrate and the second substrate; In the bonding step, a substrate detector provided in the first holding unit detects a contact state between the first substrate and the second substrate; a plurality of the substrate detection units are arranged concentrically with the first holding unit; The bonding method, wherein the substrate detection unit is a capacitance sensor or a distance measurement sensor.

7. The first holding unit has a plurality of suction units that vacuum-suck and adsorb the first substrate, 7. The joining method according to claim 6, wherein the suction timing of the suction part is controlled based on the measurement result of the displacement meter.

8. A joining method as described in claim 6 or 7, characterized in that in the pressing process, the displacement of a target provided on the actuator unit is measured by the displacement meter to measure the displacement of the actuator unit.

9. A program that runs on a computer of a control unit that controls a joining device so as to cause the joining device to perform the joining method described in any one of claims 6 to 8.

10. A readable computer storage medium storing the program described in claim 9.

Images