JP7568704B2 - Bonding device, bonding system, bonding method, program, and computer storage medium - Google Patents

Description

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

In recent years, semiconductor devices have become increasingly highly integrated. When multiple highly integrated semiconductor devices are arranged in a horizontal plane and connected with wiring to produce a product, the wiring length increases, which raises concerns about increased wiring resistance and wiring delays.

Therefore, it has been proposed to use a three-dimensional integration technology that stacks semiconductor devices three-dimensionally. In this three-dimensional integration technology, for example, a bonding system described in Patent Document 1 is used to bond two semiconductor wafers (hereinafter referred to as "wafers"). For example, the bonding system has 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 together. 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 the surfaces, and then the bonding device bonds the wafers together using van der Waals forces and hydrogen bonds (intermolecular forces).

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 wafer and the lower wafer into contact with each other, bonding the centers together to form a bonding area. After that, a so-called bonding wave is generated, in which the bonding area expands from the center of the wafer toward the outer periphery. The upper wafer and the lower wafer are then bonded.

JP 2016-039364 A

In order to suppress distortion of the laminated wafers after bonding, it is preferable for the bonding wave to expand evenly, i.e., concentrically, from the center of the wafer to the outer periphery. However, the bonding device described in the above-mentioned Patent Document 1 does not monitor the bonding wave, and therefore cannot grasp the uneven expansion of the bonding wave. Therefore, there is room for improvement in conventional wafer bonding processes.

The present invention was made in consideration of these points, and aims to inspect the state of the substrate bonding process and perform the bonding process appropriately.

In order to achieve the above-mentioned object, the present invention provides a bonding device for bonding substrates together, comprising a first holding section which adsorbs and holds a first substrate on its underside, a second holding section which is provided below the first holding section and which adsorbs and holds a second substrate on its upper surface, a pressing member which is provided on the first holding section and presses a center of the first substrate, a substrate detection section which is provided on the first holding section and detects detachment of the first substrate from the first holding section , and a control section, wherein the substrate detection section measures the flow rate or pressure of gas flowing through a suction tube for vacuuming the first substrate, and the control section grasps a bonding wave in which the bonding areas of the first substrate and the second substrate expand from the center to the outer periphery based on the detection result of the substrate detection section .

According to the present invention, the substrate detection unit can detect the detachment of the first substrate held by the first holding unit from the first holding unit. When the detachment of the first substrate occurs, the first substrate falls onto the second substrate and comes into contact with it, 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.

In the bonding device, the substrate detection unit may measure a change in airflow in the suction tube when the first substrate is detached from the first holding unit, and detect the contact state between the first substrate and the second substrate. The first holding unit may have a suction unit that sucks the first substrate by vacuum drawing, and the substrate detection unit may be provided in a suction tube connected to the suction unit.

In the bonding device, the substrate detection unit may be provided in a plurality of locations on a circumference concentric with the first holding unit. The substrate detection unit may also be provided on a plurality of circumferences.

In the bonding device, the substrate detection unit may be positioned based on the anisotropy of the Young's modulus or Poisson's ratio of the first substrate.

The present invention from another aspect is a bonding system equipped with the bonding device, comprising a processing station equipped with the bonding device, and a loading/unloading station that holds a plurality of the first substrate, the second substrate, or a laminated substrate in which the first substrate and the second substrate are bonded, and that loads and unloads the first substrate, the second substrate, or the laminated substrate to and from the processing station, the processing station having a surface modification device that modifies the surface of the first substrate or the second substrate to be bonded, a surface hydrophilization device that hydrophilizes the surface of the first substrate or the second substrate modified by the surface modification device, and 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, and the bonding device is characterized in that the bonding device bonds the first substrate and the second substrate whose surfaces have been hydrophilized by the surface hydrophilization device.

According to still another aspect, the present invention is a method for bonding substrates, comprising: an arrangement step of arranging a first substrate held on a lower surface of a first holding part and a second substrate held on an upper surface of a second holding part so as to face each other; a pressing step of lowering a pressing member provided on the first holding part and pressing a center portion of the first substrate, and pressing the center portions of the first substrate and the second substrate against each other with the pressing member; and a pressing step of removing a portion of the first substrate from the center portion of the first substrate while the center portions of the first substrate and the second substrate are in contact with each other. and a bonding process of sequentially bonding the first substrate and the second substrate toward the outer periphery, wherein in the bonding process, a substrate detection unit that measures the flow rate or pressure of gas flowing through a suction tube for vacuuming the first substrate provided in the first holding unit detects detachment of the first substrate from the first holding unit , and a control unit grasps a bonding wave in which the bonding area of the first substrate and the second substrate expands from the center toward the outer periphery based on the detection result of the substrate detection unit .

In the bonding process, the substrate detection unit may measure a change in airflow in the suction tube when the first substrate is detached from the first holding unit, and detect the contact state between the first substrate and the second substrate. In the bonding method, the first holding unit may have a suction unit that sucks the first substrate by vacuum drawing, and the substrate detection unit may be provided in a suction tube connected to the suction unit.

In the joining method, the substrate detection unit may be provided in a plurality of locations on a circumference concentric with the first holding unit. The substrate detection unit may also be provided on a plurality of circumferences.

In the bonding method, the substrate detection unit may be positioned based on the anisotropy of the Young's modulus or Poisson's ratio of the first substrate.

According to another aspect of the present invention, a program is provided that runs on a computer of a control unit that controls the joining device so as to cause the joining method to be performed by the joining device.

According to yet another aspect of the present invention, a readable computer storage medium storing the program is provided.

The present invention makes it possible to inspect the state of the substrate bonding process and perform the bonding process appropriately.

1 is a plan view showing an outline of a configuration of a joining system according to an embodiment of the present invention. 1 is a side view showing an outline of an internal configuration of a joining system according to an embodiment of the present invention. FIG. 2 is a side view showing an outline of the configuration of an upper wafer and a lower wafer. FIG. 2 is a cross-sectional view showing an outline of the configuration of a joining device. FIG. 2 is a vertical cross-sectional view showing an outline of the configuration of a joining device. 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. FIG. FIG. 13 is an explanatory diagram showing the expansion of a bonding area between wafers in a conventional method. 11 is a graph showing an example of an output result of a sensor. 1 is a flowchart showing main steps of a wafer bonding process. FIG. 2 is an explanatory diagram showing a state in which an upper wafer and a lower wafer are arranged opposite each other. 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. 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. 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; FIG. 2 is an explanatory diagram showing a state in which the upper wafer and the lower wafer are bonded together. FIG. 13 is a plan view of an upper chuck showing an arrangement of sensors according to another embodiment. FIG. 13 is a plan view of an upper chuck showing an arrangement of sensors according to another embodiment. 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.

The following describes an embodiment of the present invention with reference to the attached drawings. Note that the present invention is not limited to the embodiment described below.

1. Configuration of the joining system
First, a configuration of a bonding system according to the present embodiment will be described. Fig. 1 is a plan view showing an outline of a configuration of a bonding system 1. Fig. 2 is a side view showing an outline of an internal configuration of the bonding system 1.

In the bonding system 1, as shown in FIG. 3, for example, two substrates, wafers WU and WL, are bonded. Hereinafter, the wafer placed on the upper side is referred to as the "upper wafer WU" as the first substrate, and the wafer placed 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.

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 housing multiple wafers WU, WL, and multiple overlapping wafers WT, are loaded and unloaded between the station and 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.

The loading/unloading 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 loading and unloading the cassettes CU, CL, and CT from and to the outside of the bonding system 1. In this way, the loading/unloading 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 overlapping wafers WT. The number of cassette placement plates 11 is not limited to this embodiment and can be set arbitrarily. In addition, 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 overlapping wafers WT. In this embodiment, of the multiple cassettes CT, one cassette CT is used to collect abnormal wafers, and the other cassettes CT are used to store normal overlapped wafers WT.

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 overlapping wafers WT between cassettes CU, CL, and CT on each cassette mounting plate 11 and transition devices 50 and 51 in the third processing block G3 of processing station 3, which will be described later.

Processing station 3 is provided with multiple, for example three, processing blocks G1, G2, G3 equipped with various devices. For example, a first processing block G1 is provided on the front side of processing station 3 (negative side in the X direction in FIG. 1), and a second processing block G2 is provided on the rear side of processing station 3 (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 processing station 3 (negative side in the Y direction in FIG. 1).

For example, the first processing block G1 is provided with a surface modification device 30 that modifies the surfaces WU1, WL1 of the wafers WU, WL. In the surface modification device 30, for example, in a reduced pressure atmosphere, the processing gas, oxygen gas or nitrogen gas, is excited and turned into plasma and ionized. The oxygen ions or nitrogen ions are irradiated onto the surfaces WU1, WL1, and the surfaces WU1, WL1 are plasma-processed and modified.

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.

In the surface hydrophilization device 40, for example, while rotating the wafer WU, WL held by a spin chuck, pure water is supplied onto the wafer WU, WL. The supplied pure water then diffuses over the surfaces WU1, WL1 of the wafer WU, WL, making the surfaces WU1, WL1 hydrophilic.

For example, in the third processing block G3, transition devices 50 and 51 for wafers WU, WL, and overlapping wafer WT are provided in two stages from the bottom as shown in FIG. 2.

As shown in FIG. 1, a wafer transport area 60 is formed in the area surrounded by the first processing block G1 to the third processing block G3. In the wafer transport area 60, for example, a wafer transport device 61 is disposed.

The wafer transport device 61 has a transport arm that can move, for example, vertically, horizontally (Y direction, X direction), and around a vertical axis. The wafer transport device 61 moves within the wafer transport area 60 and can transport wafers WU, WL, and overlapped wafers WT to predetermined devices within the surrounding first processing block G1, second processing block G2, and third processing block G3.

The above bonding system 1 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 wafers 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 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), magnet optical disk (MO), or memory card, and may be installed in the control unit 70 from the storage medium H.

2. Configuration of the joining device
Next, the configuration of the above-mentioned joining device 41 will be described.

<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 the overlapped wafer WT is formed on a side surface 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.

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 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.

A transition 110 is provided on the positive Y-direction side of the transfer area 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 it at the same time.

A wafer transfer mechanism 111 is provided in the transfer region T1. The wafer transfer mechanism 111 has a transfer arm that can move, 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 wafers WU, WL, and overlapping wafers WT within the transfer region T1 or between the transfer region T1 and the processing region T2.

On the negative Y-direction side of the transfer region T1, a position adjustment mechanism 120 is provided to adjust the horizontal orientation of the wafers WU and WL. The position adjustment mechanism 120 has a base 121 equipped with a holding unit (not shown) that holds and rotates the wafers WU and WL, and a detection unit 122 that detects the position of the notch portion 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 position of the notch portion of the wafers WU and WL with the detection unit 122, thereby adjusting the position of the notch portion and adjusting the horizontal orientation of the wafers WU and WL. Note that 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.

The transfer area T1 is also provided with an inversion mechanism 130 that inverts the front and back sides of the upper wafer WU. 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.

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 can also rotate around the drive unit 133 and move in the horizontal direction (X direction). Below the drive unit 133, another drive unit (not shown) having, for example, a motor is provided. 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 around a horizontal axis and move vertically and horizontally. 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 the upper chuck 140 described later.

In the processing region T2, there are provided an upper chuck 140 as a first holding part that holds the upper wafer WU by suction on its underside, and a lower chuck 141 as a second holding part 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 so that it can be positioned 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 positioned opposite each other.

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. In other words, the upper chuck 140 is fixed to the processing vessel 100 via the upper chuck holder 150.

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. For example, a CCD camera is used as the upper imaging part 151.

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 surface WU1 of the upper wafer WU held by the upper chuck 140. In other words, 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.

The lower chuck stage 160 is supported by a first lower chuck moving part 162 provided below the lower chuck stage 160, which 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. The first lower chuck moving part 162 is also configured to be able to move the lower chuck 141 in the vertical direction and rotate around a vertical axis.

The support table 163 is attached to a pair of rails 164, 164 that are provided on the underside of the support table 163 and extend 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.

The pair of rails 164, 164 are disposed on the second lower chuck moving part 165. The second lower chuck moving part 165 is attached to a pair of rails 166, 166 that are provided on the lower surface side of the second lower chuck moving part 165 and extend in the horizontal direction (Y direction). The second lower chuck moving part 165 is configured to be freely 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 are disposed on a mounting table 167 provided on the bottom surface of the processing vessel 100.

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

The upper chuck 140 employs a pin chuck system as shown in Figs. 6 and 7. The upper chuck 140 has a main body 170 having a diameter equal to or greater than the diameter of the upper wafer WU in a plan view. The lower surface of the main body 170 is provided with a plurality of pins 171 that contact the rear surface WU2 of the upper wafer WU. Note that the pins 171 are not shown in Fig. 7.

The lower surface of the main body 170 is provided with a number of suction sections 172-174 that suction the upper wafer WU by vacuuming it. Each of the suction sections 172-174 has the same height as the pin 171 and contacts the back surface WU2 of the upper wafer WU.

The first suction portion 172 has an arc shape in a plan view. A plurality of first suction portions 172 (e.g., eight) 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.

A first vacuum pump 172b is connected to each of these eight first suction parts 172 via a first suction pipe 172a. By drawing a vacuum with the first vacuum pump 172b, the eight first suction parts 172 can individually suction the upper wafer WU.

The second suction portion 173, like the first suction portion 172, has an arc shape in a plan view. The second suction portion 173 is arranged on a concentric circle with the main body portion 170, closer to the inner circumference of the main body portion 170 than the first suction portion 172, with multiple second suction portions 173 (e.g., eight of them) lined up in the circumferential direction at predetermined intervals. Note that the center of the first suction portion 172 and the center of the second suction portion 173 are arranged on the center line of the main body portion 170.

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

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 drawing a vacuum with the third vacuum pump 174b.

The main body 170 is provided with a sensor 175 as a substrate detection unit that detects the detachment 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.

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 tip of an actuator portion 191 of a pressing member 190 (described later) is inserted into the through hole 176.

<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.

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 area at the center of both wafers. After that, a bonding wave is generated in which the bonding area expands from the center of both wafers WU, WL toward the outer periphery, and the surfaces WU1, WL1 of the upper wafer WU and the lower wafer WL are bonded together over the entire surface.

A sensor 175 is provided in the main body 170 to detect this bonding wave.

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, light is emitted from the sensor 175 toward the upper wafer WU, and the sensor 175 receives the reflected light and measures the amount of light received. Then, by measuring the amount of light received, 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), 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 inclination of the upper wafer WU is small), meaning that the upper wafer WU is separated from the upper chuck 140 and in contact with the lower wafer WL. Therefore, by measuring the amount of reflected light with the sensor 175, the contact state of 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.

For example, the sensor 175 may be a capacitance sensor or a distance measurement sensor. 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 measurement 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 way, the contact state of 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.

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 FIG. 6 and FIG. 7, and the sensor 175 is provided on a suction tube (not shown) connected to the suction pad. Note that the suction pad is not intended to suction and hold the upper wafer WU, 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 abutment state of the upper wafer WU and the lower wafer WL), and can grasp the bonding wave. The sensor 175 may be provided in each of the first suction tube 172a of the first suction unit 172 and the second suction tube 173a of the second suction unit 173.

As described above, the sensors 175 are arranged at predetermined intervals between the first suction section 172 and the second suction section 173, concentrically with the main body section 170. Next, the arrangement of the sensors 175 will be described.

The arrangement of the sensor 175 is determined according to the physical properties of the upper wafer WU, such as the anisotropy of Young's modulus and Poisson's ratio. Figure 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 Figure 8, when performing a bonding process, the bonding area A does not expand concentrically but expands unevenly. Note that Figure 8 is a plan view of the upper wafer WU held by the upper chuck 140, viewed from below.

The upper wafer WU is a single crystal silicon wafer with a [100] crystal direction perpendicular to the surface WU1. The notch N of the upper wafer WU is formed on the outer edge of the [011] crystal direction of the upper wafer WU. The bonding area A expands faster in a 45° periodic direction (45°, 135°, 225°, 315° directions shown in FIG. 8, hereinafter sometimes referred to as the 45° direction) based on a direction from the center of the upper wafer WU toward the [010] crystal direction 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 the 90° direction) based on a direction from the center of the upper wafer WU toward the [010] crystal direction parallel to the surface WU1 of the upper wafer WU. As a result, the shape of the joining area A, which was circular when joining began (center joining), approaches a rectangle with vertices at 45° angles as it expands.

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

The detection results of the sensor 175 are output to the control unit 70. The control unit 70 controls the operation of the suction units 172 to 174 based on the detection results of the sensor 175.

Figure 9 is a graph showing an example of the output result of the sensor 175. The horizontal axis of Figure 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 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 area A has not yet been reached. 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 is in contact with the lower wafer WL, and the bonding area A has been reached.

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

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.

Specifically, the control unit 70 controls the second suction unit 173 to delay the timing at which it releases the upper wafer WU in the 45° direction, and to speed up the timing at which it releases the upper wafer WU in the 90° direction. This makes it possible to make the timing at which the bonding area A arrives at the positions of the eight sensors 175 almost the same. This makes it possible to make the expansion of the bonding area A uniform, and to make the bonding wave uniform (close to a concentric shape).

In this embodiment, the suction timing of the second suction unit 173 is controlled based on the detection result of the sensor 175. However, the suction force of the second suction unit 173 may be controlled. The other suction units 172 and 174 may also be controlled based on the detection result of the sensor 175.

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

The upper chuck holding part 150 has an upper chuck stage 180 provided on the upper surface of the main body part 170 of the upper chuck 140 as shown in FIG. 5. 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.

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 as shown in FIG. 6. The pressing member 190 has an actuator portion 191 and a cylinder portion 192.

The actuator unit 191 generates a constant pressure in a fixed direction using air supplied from an electro-pneumatic regulator (not shown), and can generate a constant pressure regardless of the position of the pressure application point. The air from the electro-pneumatic regulator allows the actuator unit 191 to contact 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 can be raised and lowered vertically by passing through the through hole 176 using the air from the electro-pneumatic regulator.

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

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. The pressing member 190 can press the center of the upper wafer WU and the center of the lower wafer WL by abutting them together when bonding the wafers WU and WL, which will be described later.

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

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. The upper surface of the main body 200 is provided with a plurality of pins 201 that contact the back surface WL2 of the lower wafer WL. 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.

In addition, an inner rib 203 is provided on the upper surface of the main body 200 inside the outer rib 202. The inner rib 203 has the same height as the pin 201 and 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. The 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.

A first suction port 205a is formed on the upper surface of the main body 200 in the first suction region 204a to suction the lower wafer WL. 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.

In addition, a second suction port 205b is formed on the upper surface of the main body 200 in the second suction region 204b to suction the lower wafer WL. 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.

Then, the 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 the 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 also configured to be able to evacuate the lower wafer WL for each of the first suction region 204a and the second suction region 204b.

In the lower chuck 141, near the center of the main body 200, through holes (not shown) that penetrate the main body 200 in the thickness direction are formed in, for example, three places. The through holes are adapted to receive lifting pins provided below the first lower chuck moving part 162.

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 of 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.

The operation of each part of the joining device 41 is controlled by the control unit 70 described above.

3. Joining Treatment Method
Next, a description will be given of a bonding method for the wafers WU and WL 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.

First, a cassette CU containing multiple upper wafers WU, a cassette CL containing multiple lower wafers WL, and an empty cassette CT are placed on a predetermined cassette placement plate 11 in the loading/unloading station 2. After that, 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.

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 and 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 plasma-processed. Then, the surface WU1 of the upper wafer WU is modified (step S1 in FIG. 10).

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).

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

Then, 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 area 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.

Then, 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 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, and the upper wafer WU is vacuum-drawn by the suction units 172, 173, and 174, and the upper wafer WU is adsorbed and held by the upper chuck 140.

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 in the processing station 3.

Next, the lower wafer WL is transferred to the surface modification device 30 by the wafer transfer device 61, and 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.

Then, 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 the surface WL1 is 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 the same as in step S2 described above.

The lower wafer WL is then transferred to the bonding device 41 by the wafer transfer device 61. The lower wafer WL that has been transferred to the bonding device 41 is transferred to the position adjustment mechanism 120 by the wafer transfer mechanism 111 via the transition 110. The horizontal orientation of the lower wafer WL is then adjusted by the position adjustment mechanism 120 (step S8 in FIG. 10).

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

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 horizontally (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 captured images are output to the control part 70. In the control part 70, the lower chuck 141 is moved 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 based on the images captured by the upper imaging part 151 and the images captured by the lower imaging part 161. In this way, the horizontal positions of the upper wafer WU and the lower wafer WL are adjusted (step S10 in Figure 10).

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.

Then, 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.

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.

In this embodiment, the case will be described where the suction timing of the second suction unit 173 is set in advance so that the bonding wave is uniform as described above. That is, for example, the sensor 175 detects the expansion of the bonding area 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.

First, as shown in FIG. 12, the actuator part 191 is lowered by the cylinder part 192 of the pressing member 190. As the actuator part 191 is lowered, the center 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 electro-pneumatic regulator. Then, the pressing member 190 abuts and presses the center of the upper wafer WU and the center of the lower wafer WL (step S13 in FIG. 10).

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 part 172, while the second vacuum pump 173b and the third vacuum pump 174b are kept operating to vacuum the upper wafer WU by the second suction part 173 and the third suction part 174.

When the center of the upper wafer WU and the center of the lower wafer WL are brought into contact and pressed, bonding begins between the centers. 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 form hydrogen bonds (intermolecular forces), and the surfaces WU1 and WL1 are firmly bonded to each other. In this way, the bonding region A is formed.

After that, a bonding wave is generated between the upper wafer WU and the lower wafer WU, in which the bonding area A expands from the center of the upper wafer WU and the lower wafer WU toward the outer periphery.

As shown in FIG. 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 suction of the upper wafer WU from the second suction part 173. At this time, as described above, the suction timing of the eight second suction parts 173 is made different. That is, the timing at which the second suction part 173 in the 45° direction releases the upper wafer WU is delayed, and the timing at which the second suction part 173 in the 90° direction releases the upper wafer WU is advanced. This makes it possible to make the timing at which the bonding area A arrives almost the same at the positions of the eight sensors 175, and to make the bonding wave uniform.

Furthermore, as shown in FIG. 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 and contacted sequentially onto the lower wafer WL, and the bonding between the above-mentioned surfaces WU1, WL1 due to the van der Waals forces and hydrogen bonds gradually spreads. In this way, the surface WU1 of the upper wafer WU and the surface WL1 of the lower wafer WL contact each other over their entire surfaces, and the upper wafer WU and the lower wafer WL are bonded (step S14 in FIG. 10). At this time, since the bonding wave is uniform, distortion of the bonded overlapped wafers WT can be suppressed.

In step S14, the eight sensors 175 are used to detect the bonding area A, 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 cases, a warning can be issued to improve 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 subsequent upper wafer WU and lower wafer WL.

Then, as shown in FIG. 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.

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 load/unload station 2 to the cassette CT on the specified cassette mounting plate 11. In this way, the series of bonding processes for the wafers WU and WL is completed.

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.

In addition, since the bonding system 1 of this embodiment includes a surface modification device 30, a surface hydrophilization device 40, and a bonding device 41, the bonding of the wafers WU and WL can be performed efficiently within a single system. Therefore, the throughput of the wafer bonding process can be improved.

4. Other embodiments
Next, another embodiment of the present invention will be described.

In the above embodiment of the upper chuck 140, the sensors 175 are arranged at predetermined intervals between the first suction portion 172 and the second suction portion 173, on a concentric circle with the main body portion 170, but the arrangement of the sensors 175 is not limited to this.

As shown in FIG. 16, in addition to being between the first suction portion 172 and the second suction portion 173, the sensor 175 may be arranged in a plurality of positions, for example eight, concentrically with the main body portion 170 and spaced apart from each other at a predetermined interval on the inner periphery 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 periphery side of the second suction portion 173 is referred to as sensor 175b.

In such a 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.

Sensor 175a may be omitted and only sensor 175b may be provided. However, since sensor 175a is positioned away from the center of main body 170, it can more clearly grasp the uneven diffusion of bonding region A than sensor 175b. Specifically, for example, if the diameter of upper wafer WU is 300 mm, sensor 175a is preferably positioned more than 240 mm outside the center of main body 170.

Also, as shown in FIG. 8, the conventional joint area A expands to a substantially rectangular shape. Considering the symmetry of the expansion of this joint area A, it is possible to reduce the number of sensors 175.

For example, as shown in Figures 17(a) and (b), 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° and 90° directions. In such a case, the sensor 175 in the 45° direction may be used to estimate the expansion of the joining area A in the other 45° direction, and the sensor 175 in the 90° direction may be used to estimate the expansion of the joining area A in the other 90° direction.

However, as shown in FIG. 7, if the sensors 175 are provided around the entire circumference of the main body 170, it is possible to grasp 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 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 will expand more 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, the bonding wave can be properly grasped.

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.

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 of the upper wafer WU and the center of the lower wafer WL have come into contact.

In this way, the start of the bonding area A can be grasped based on the measurement results by the laser displacement meter 300, so the bonding wave can be grasped more appropriately. In addition, it is also possible to control the suction timing of the suction parts 172 to 174 based on the measurement results by the laser displacement meter 300.

The displacement meter provided on the pressing member 190 is not limited to the laser displacement meter 300, and can be any meter that can measure the displacement of the actuator part 191.

In the upper chuck 140 of 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 operation of 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.

Similarly, for the eight first suction sections 172, one first vacuum pump 172b may collectively control the operation of multiple first suction sections 172.

Furthermore, 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. Furthermore, in main body unit 170, three or more suction units may be provided.

In the above embodiment of the joining device 41, 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.

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.

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.

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

Although the preferred embodiment of the present invention has been described above with reference to the attached drawings, the present invention is not limited to such an example. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these 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) and mask reticles for photomasks, other than wafers.

REFERENCE SIGNS LIST 1 Bonding system 2 Loading/unloading station 3 Processing station 30 Surface modification device 40 Surface hydrophilization device 41 Bonding device 61 Wafer transfer device 70 Control unit 140 Upper chuck 141 Lower chuck 172 First suction unit 173 Second suction unit 174 Third suction unit 175 Sensor 190 Pressing member 300 Laser displacement meter WU Upper wafer WL Lower wafer WT Overlapped wafer

Claims (15)

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 removal of the first substrate from the first holding unit ;
A control unit,
the substrate detection unit measures a flow rate or a pressure of a gas flowing through a suction pipe for evacuating the first substrate ;
A bonding apparatus characterized in that the control unit grasps a bonding wave in which the bonding area of the first substrate and the second substrate expands from the center toward the outer periphery based on the detection result of the substrate detection unit .
The bonding device according to claim 1, characterized in that the substrate detection unit measures the change in the airflow in the suction tube when the first substrate is detached from the first holding unit, and detects the contact state between the first substrate and the second substrate. the first holding unit has a suction unit that suctions the first substrate by vacuum,
3. The bonding apparatus according to claim 1, wherein the substrate detection unit is provided on a suction pipe connected to the suction unit. The bonding device according to any one of claims 1 to 3, characterized in that the substrate detection units are provided in multiple units on a concentric circle with the first holding unit. The bonding device according to claim 4, characterized in that the substrate detection units are provided on multiple circumferences. The bonding device according to any one of claims 1 to 5, characterized in that the substrate detection unit is positioned based on the anisotropy of the Young's modulus or Poisson's ratio of the first substrate. A bonding system comprising the bonding device according to any one of claims 1 to 6,
a processing station including the bonding device;
a loading/unloading station that holds a plurality of the first substrates, the second substrates, or a laminated substrate in which the first substrate and the second substrate are bonded, and that loads/unloads the first substrates, the second substrates, or the laminated substrate into/from the processing station,
The processing station comprises:
a surface modification device for modifying a 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, the surfaces of which have been hydrophilized by the surface hydrophilization apparatus. A 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;
thereafter, a pressing step of lowering a pressing member provided on the first holding part and pressing the center portion of the first substrate, and pressing the center portion of the first substrate and the center portion of the second substrate against each other by the pressing member;
thereafter, a bonding process of sequentially bonding the first substrate and the second substrate from the center portion of the first substrate toward the outer periphery thereof while the center portion of the first substrate and the center portion of the second substrate are in contact with each other,
a substrate detection unit that measures a flow rate or pressure of gas flowing through a suction tube provided on the first holding unit for vacuuming the first substrate in the bonding process, and a control unit that grasps a bonding wave in which the bonding area of the first substrate and the second substrate expands from the center to the outer periphery based on the detection result of the substrate detection unit .
The bonding method according to claim 8, characterized in that in the bonding process, the substrate detection unit measures the change in the airflow in the suction tube when the first substrate is detached from the first holding unit, and detects the contact state between the first substrate and the second substrate. the first holding unit has a suction unit that suctions the first substrate by vacuum,
10. The bonding method according to claim 8, wherein the substrate detection unit is provided on a suction pipe connected to the suction unit. The joining method according to any one of claims 8 to 10, characterized in that the substrate detection unit is provided in a plurality of units on a concentric circle with the first holding unit. The joining method according to claim 11, characterized in that the substrate detection units are provided on multiple circumferences. The bonding method according to any one of claims 8 to 12, characterized in that the substrate detection unit is positioned based on the anisotropy of the Young's modulus or Poisson's ratio of the first substrate. A program that runs on a computer of a control unit that controls a joining device to cause the joining device to execute the joining method described in any one of claims 8 to 13. A readable computer storage medium storing the program according to claim 14.

Images