JP7546403B2 - Bonding device and bonding method - Google Patents

Description

This disclosure relates to a joining device and a joining method.

A conventional method for bonding substrates such as semiconductor wafers involves modifying the surfaces of the substrates to be bonded, making the modified substrate surfaces hydrophilic, and bonding the hydrophilized substrates together using van der Waals forces and hydrogen bonds (intermolecular forces) (see Patent Document 1).

JP 2017-005058 A

This disclosure provides technology that can improve the bonding quality of laminated substrates.

A bonding device according to one aspect of the present disclosure includes a first holding unit, a second holding unit, a striker, a processing vessel, a gas discharge unit, and a control unit. The first holding unit adsorbs and holds the first substrate from above. The second holding unit adsorbs and holds the second substrate from below. The striker presses the center of the first substrate from above to contact the second substrate. The processing vessel accommodates the first holding unit, the second holding unit, and the striker. The gas discharge unit discharges a gas having a humidity different from that of the atmosphere in the processing vessel. The control unit controls each unit. In addition, the control unit discharges the gas from the gas discharge unit between the first substrate and the second substrate immediately before the first substrate facing the second substrate is pressed by the striker.

This disclosure makes it possible to improve the bonding quality of laminated substrates.

FIG. 1 is a schematic plan view showing a configuration of a joining system according to an embodiment. FIG. 2 is a schematic side view showing the configuration of the joining system according to the embodiment. FIG. 3 is a schematic side view of the upper wafer and the lower wafer according to the embodiment. FIG. 4 is a schematic cross-sectional view showing the configuration of a surface modification apparatus according to an embodiment. FIG. 5 is a schematic plan view showing the configuration of the joining device according to the embodiment. FIG. 6 is a schematic side view showing the configuration of the joining device according to the embodiment. FIG. 7 is a schematic side view showing the configuration of an upper chuck and a lower chuck of the joining device according to the embodiment. FIG. 8 is an enlarged side view showing the configuration of the suction and discharge mechanism according to the embodiment. FIG. 9 is a flowchart illustrating a part of a processing procedure of the processing executed by the bonding system according to the embodiment. FIG. 10 is a timing chart showing the operation of each unit in the joining process according to the embodiment. FIG. 11 is a diagram for explaining details of the joining process according to the embodiment. FIG. 12 is a timing chart showing the operation of each unit in the joining process according to the modified example of the embodiment. FIG. 13 is a top view showing an example of an arrangement of a gas suction section and a gas discharge section according to a modified example of the embodiment. FIG. 14 is a top view showing another example of the arrangement of the gas suction section and the gas discharge section according to the modified example of the embodiment. FIG. 15 is a flowchart illustrating a procedure of the joining process executed by the joining device according to the embodiment.

Below, with reference to the attached drawings, an embodiment of the joining device and joining method disclosed in the present application will be described in detail. Note that the present disclosure is not limited to the embodiment described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from reality. Furthermore, there may be parts in which the dimensional relationships and ratios differ between the drawings.

A conventional method for bonding substrates such as semiconductor wafers involves modifying the surfaces of the substrates to be bonded, making the modified substrate surfaces hydrophilic, and bonding the hydrophilized substrates together using van der Waals forces and hydrogen bonds (intermolecular forces).

On the other hand, when hydrophilized substrates are bonded together to form a polymerized substrate, voids (hereinafter referred to as edge voids) may occur on the periphery of the polymerized substrate. In addition, when forming such a polymerized substrate, variations in the state of the bonded interface may occur, resulting in significant distortion of the polymerized substrate.

If the bonding quality of the laminated substrate deteriorates in this way, there is a risk that the yield of elements formed in the laminated substrate will decrease.

Therefore, there is a need to develop technology that can overcome the above-mentioned problems and improve the bonding quality of laminated substrates.

<Configuration of the joining system>
First, the configuration of a bonding system 1 according to an embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a schematic plan view showing the configuration of the bonding system 1 according to the embodiment, and Fig. 2 is a schematic side view of the same. Fig. 3 is a schematic side view of an upper wafer and a lower wafer according to the embodiment. Note that, in order to make the description easier to understand, each of the drawings referred to below may show an orthogonal coordinate system in which the vertical upward direction is the positive direction of the Z axis.

The bonding system 1 shown in FIG. 1 forms a laminated wafer T by bonding a first substrate W1 and a second substrate W2.

The first substrate W1 is, for example, a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer, on which multiple electronic circuits are formed. The second substrate W2 is, for example, a bare wafer on which no electronic circuits are formed. The first substrate W1 and the second substrate W2 have approximately the same diameter. Note that electronic circuits may be formed on the second substrate W2.

In the following, the first substrate W1 will be referred to as the "upper wafer W1" and the second substrate W2 will be referred to as the "lower wafer W2." In other words, the upper wafer W1 is an example of a first substrate, and the lower wafer W2 is an example of a second substrate. Furthermore, when referring to the upper wafer W1 and the lower wafer W2 collectively, they may be referred to as "wafer W."

Furthermore, in the following, as shown in FIG. 3, of the surfaces of the upper wafer W1, the surface that is bonded to the lower wafer W2 is referred to as the "bonding surface W1j," and the surface opposite the bonding surface W1j is referred to as the "non-bonding surface W1n." Furthermore, of the surfaces of the lower wafer W2, the surface that is bonded to the upper wafer W1 is referred to as the "bonding surface W2j," and the surface opposite the bonding surface W2j is referred to as the "non-bonding surface W2n."

As shown in FIG. 1, the joining system 1 includes a loading/unloading station 2 and a processing station 3. The loading/unloading station 2 and the processing station 3 are arranged in the positive direction of the X-axis in the order of the loading/unloading station 2 and the processing station 3. The loading/unloading station 2 and the processing station 3 are also connected together.

The loading/unloading station 2 includes a mounting table 10 and a transfer area 20. The mounting table 10 includes multiple mounting plates 11. Each mounting plate 11 is loaded with a cassette C1, C2, or C3 that stores multiple substrates (e.g., 25 substrates) in a horizontal position. For example, cassette C1 is a cassette that stores an upper wafer W1, cassette C2 is a cassette that stores a lower wafer W2, and cassette C3 is a cassette that stores a laminated wafer T.

The transport area 20 is disposed adjacent to the mounting table 10 on the positive side of the X-axis. The transport area 20 is provided with a transport path 21 extending in the Y-axis direction and a transport device 22 movable along the transport path 21.

The transfer device 22 can move not only in the Y-axis direction but also in the X-axis direction and can rotate around the Z-axis. The transfer device 22 transfers the upper wafer W1, the lower wafer W2, and the overlapped wafer T between the cassettes C1 to C3 placed on the mounting plate 11 and the third processing block G3 of the processing station 3, which will be described later.

The number of cassettes C1 to C3 placed on the loading plate 11 is not limited to that shown in the figure. In addition to the cassettes C1, C2, and C3, cassettes for recovering defective substrates may also be placed on the loading plate 11.

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

The first processing block G1 is provided with a surface modification device 30 that modifies the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 using plasma of a processing gas. The surface modification device 30 modifies the bonding surfaces W1j, W2j by breaking the SiO2 bonds on the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 to single-bonded SiO, thereby making the bonding surfaces W1j, W2j more easily hydrophilized thereafter.

In the surface modification device 30, for example, a given process gas is excited to be turned into plasma and ionized in a reduced pressure atmosphere. Ions of elements contained in the process gas are then irradiated onto the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2, whereby the bonding surfaces W1j, W2j are subjected to plasma processing and modified. Details of the surface modification device 30 will be described later.

The second processing block G2 is provided with a surface hydrophilization device 40 and a bonding device 41. The surface hydrophilization device 40 hydrophilizes the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2, for example, using pure water, and cleans the bonding surfaces W1j, W2j.

In the surface hydrophilization device 40, for example, while rotating the upper wafer W1 or the lower wafer W2 held by a spin chuck, pure water is supplied onto the upper wafer W1 or the lower wafer W2. As a result, the pure water supplied onto the upper wafer W1 or the lower wafer W2 spreads over the bonding surfaces W1j, W2j of the upper wafer W1 or the lower wafer W2, and the bonding surfaces W1j, W2j are hydrophilized.

The bonding device 41 bonds the upper wafer W1 and the lower wafer W2. Details of the bonding device 41 will be described later.

As shown in FIG. 2, the third processing block G3 has transition (TRS) devices 50, 51 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T arranged in two stages from the bottom up.

As shown in FIG. 1, a transport area 60 is formed in the area surrounded by the first processing block G1, the second processing block G2, and the third processing block G3. A transport device 61 is disposed in the transport area 60. The transport device 61 has a transport arm that is movable, for example, in the vertical direction, the horizontal direction, and around the vertical axis.

The transfer device 61 moves within the transfer area 60 and transfers the upper wafer W1, the lower wafer W2, and the overlapped wafer T to given devices within the first processing block G1, the second processing block G2, and the third processing block G3 adjacent to the transfer area 60.

The bonding system 1 also includes a control device 4. The control device 4 controls the operation of the bonding system 1. The control device 4 is, for example, a computer, and includes a control unit 5 and a memory unit 6. The memory unit 6 stores programs that control various processes such as the bonding process. The control unit 5 controls the operation of the bonding system 1 by reading and executing the programs stored in the memory unit 6.

The program may be recorded on a computer-readable recording medium and installed from the recording medium into the memory unit 6 of the control device 4. Examples of computer-readable recording media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

<Configuration of Surface Modification Device>
Next, the configuration of the surface modification device 30 will be described with reference to Fig. 4. Fig. 4 is a schematic cross-sectional view showing the configuration of the surface modification device 30.

As shown in FIG. 4, the surface modification device 30 has a processing vessel 70 whose interior can be sealed. A loading/unloading port 71 for the upper wafer W1 or the lower wafer W2 is formed on the side of the processing vessel 70 facing the transfer area 60 (see FIG. 1), and a gate valve 72 is provided at the loading/unloading port 71.

A stage 80 is disposed inside the processing vessel 70. The stage 80 is, for example, a lower electrode, and is made of a conductive material such as aluminum. A plurality of driving units 81, each equipped with, for example, a motor, are provided below the stage 80. The plurality of driving units 81 raise and lower the stage 80.

An exhaust ring 103 with multiple baffle holes is disposed between the stage 80 and the inner wall of the processing vessel 70. The exhaust ring 103 allows the atmosphere in the processing vessel 70 to be exhausted uniformly from within the processing vessel 70.

A power supply rod 104 made of a conductor is connected to the underside of the stage 80. A first high-frequency power supply 106 is connected to the power supply rod 104 via a matching device 105, which may be, for example, a blocking capacitor. During plasma processing, a given high-frequency voltage is applied to the stage 80 from the first high-frequency power supply 106.

An upper electrode 110 is disposed inside the processing vessel 70. The upper surface of the stage 80 and the lower surface of the upper electrode 110 are disposed parallel to each other and facing each other with a given distance in between. The distance between the upper surface of the stage 80 and the lower surface of the upper electrode 110 is adjusted by the driving unit 81.

The upper electrode 110 is grounded and connected to the ground potential. Because the upper electrode 110 is grounded in this manner, damage to the underside of the upper electrode 110 during plasma processing can be suppressed.

In this way, a high-frequency voltage is applied from the first high-frequency power supply 106 to the stage 80, which is the lower electrode, to generate plasma inside the processing vessel 70.

In the embodiment, the stage 80, the power supply rod 104, the matching box 105, the first high frequency power supply 106, the upper electrode 110, and the matching box are an example of a plasma generation mechanism that generates plasma of the processing gas in the processing vessel 70. The first high frequency power supply 106 is controlled by the control unit 5 of the control device 4 described above.

A hollow portion 120 is formed inside the upper electrode 110. A gas supply pipe 121 is connected to the hollow portion 120. The gas supply pipe 121 is connected to a gas supply source 122 that stores a processing gas and a static elimination gas inside. The gas supply pipe 121 is also provided with a group of supply devices 123 including valves and flow rate regulators that control the flow of the processing gas and the static elimination gas.

The process gas and static elimination gas supplied from the gas supply source 122 are flow-controlled by a supply device group 123 and introduced into the hollow portion 120 of the upper electrode 110 via a gas supply pipe 121. For example, oxygen gas, nitrogen gas, argon gas, etc. are used as the process gas. For example, inert gas such as nitrogen gas or argon gas is used as the static elimination gas.

Inside the hollow portion 120, a baffle plate 124 is provided to promote uniform diffusion of the processing gas and the static elimination gas. The baffle plate 124 has a large number of small holes. The lower surface of the upper electrode 110 has a large number of gas outlets 125 formed therein for ejecting the processing gas and the static elimination gas from the hollow portion 120 into the inside of the processing vessel 70.

The processing vessel 70 is provided with an intake port 130. The intake port 130 is connected to an intake pipe 132 that communicates with a vacuum pump 131 that reduces the pressure inside the processing vessel 70 to a given vacuum level.

The upper surface of the stage 80, i.e., the surface facing the upper electrode 110, is a horizontal surface that is circular in plan view and has a diameter larger than the upper wafer W1 and the lower wafer W2. A stage cover 90 is placed on the upper surface of the stage 80, and the upper wafer W1 or the lower wafer W2 is placed on the placement portion 91 of the stage cover 90.

<Configuration of the bonding device>
Next, the configuration of the joining device 41 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a schematic plan view showing the configuration of the joining device 41 according to the embodiment, and Fig. 6 is a schematic side view showing the configuration of the joining device 41 according to the embodiment.

As shown in FIG. 5, the bonding device 41 has a processing vessel 190 whose interior can be sealed. A loading/unloading port 191 for the upper wafer W1, the lower wafer W2, and the overlapping wafer T is formed on the side of the processing vessel 190 facing the transfer area 60, and an opening/closing shutter 192 is provided at the loading/unloading port 191.

The interior of the processing vessel 190 is divided into a transfer region T1 and a processing region T2 by an inner wall 193. The above-mentioned loading/unloading port 191 is formed on the side of the processing vessel 190 in the transfer region T1. In addition, loading/unloading ports 194 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T are also formed in the inner wall 193.

The inside of the processing vessel 190 is maintained at a given constant humidity by a humidity retention mechanism (not shown). This allows the bonding device 18 to perform the bonding process between the upper wafer W1 and the lower wafer W2 in a stable environment.

A transition 200 is provided on the negative Y-axis side of the transfer region T1 for temporarily placing the upper wafer W1, the lower wafer W2, and the overlapped wafer T. The transition 200 is formed, for example, in two stages, and any two of the upper wafer W1, the lower wafer W2, and the overlapped wafer T can be placed thereon at the same time.

A transfer mechanism 201 is provided in the transfer region T1. The transfer mechanism 201 has a transfer arm that is movable, for example, in the vertical direction, the horizontal direction, and around a vertical axis. The transfer mechanism 201 transfers the upper wafer W1, the lower wafer W2, and the overlapped wafer T within the transfer region T1 or between the transfer region T1 and the processing region T2.

A position adjustment mechanism 210 that adjusts the horizontal orientation of the upper wafer W1 and the lower wafer W2 is provided on the positive Y-axis side of the transfer region T1. This position adjustment mechanism 210 detects the positions of the notches of the upper wafer W1 and the lower wafer W2 with a detection unit (not shown) while rotating the upper wafer W1 and the lower wafer W2 that are held by suction on a holding unit (not shown).

As a result, the position adjustment mechanism 210 adjusts the position of the notch portion to adjust the horizontal orientation of the upper wafer W1 and the lower wafer W2. In addition, an inversion mechanism 220 that inverts the front and back sides of the upper wafer W1 is provided in the transfer region T1.

As shown in FIG. 6, an upper chuck 230 and a lower chuck 231 are provided in the processing region T2. The upper chuck 230 suction-holds the upper wafer W1 from above. The lower chuck 231 is provided below the upper chuck 230 and suction-holds the lower wafer W2 from below. The upper chuck 230 is an example of a first holding part, and the lower chuck 231 is an example of a second holding part.

As shown in FIG. 6, the upper chuck 230 is supported by a support member 300 provided on the ceiling surface of the processing vessel 190. The support member 300 is provided with an upper imaging unit (not shown) that images the bonding surface W2j of the lower wafer W2 held by the lower chuck 231. The upper imaging unit is provided adjacent to the upper chuck 230.

As shown in Figs. 5 and 6, the lower chuck 231 is supported by a first lower chuck moving part 310 provided below the lower chuck 231. The first lower chuck moving part 310 moves the lower chuck 231 in the horizontal direction (Y-axis direction) as described below. The first lower chuck moving part 310 is configured to be able to move the lower chuck 231 vertically and to rotate it around a vertical axis.

As shown in FIG. 5, the first lower chuck moving part 310 is provided with a lower imaging part (not shown) that images the bonding surface W1j of the upper wafer W1 held by the upper chuck 230. The lower imaging part is provided adjacent to the lower chuck 231.

As shown in Figs. 5 and 6, the first lower chuck moving part 310 is attached to a pair of rails 315 that are provided on the underside of the first lower chuck moving part 310 and extend in the horizontal direction (Y-axis direction). The first lower chuck moving part 310 is configured to be freely movable along the rails 315.

The pair of rails 315 are provided on the second lower chuck moving part 316. The second lower chuck moving part 316 is attached to a pair of rails 317 that are provided on the underside of the second lower chuck moving part 316 and extend in the horizontal direction (X-axis direction).

The second lower chuck moving part 316 is configured to be movable along the rails 317, i.e., to move the lower chuck 231 in the horizontal direction (X-axis direction). The pair of rails 317 are provided on a mounting table 318 provided on the bottom surface of the processing vessel 190.

Next, the configuration of the upper chuck 230 and the lower chuck 231 in the joining device 41 will be described with reference to FIG. 7. FIG. 7 is a schematic side view showing the configuration of the upper chuck 230 and the lower chuck 231 of the joining device 41 according to the embodiment.

The upper chuck 230 is generally disk-shaped and, as shown in FIG. 7, is partitioned into multiple, for example, three, regions 230a, 230b, and 230c. These regions 230a, 230b, and 230c are provided in this order from the center of the upper chuck 230 toward the periphery (outer periphery). Region 230a has a circular shape in a plan view, and regions 230b and 230c have annular shapes in a plan view.

Each of the regions 230a, 230b, and 230c is provided with a central suction pipe 240a, an intermediate suction pipe 240b, and a peripheral suction pipe 240c for suction-holding the upper wafer W1, as shown in FIG. 7.

The central suction pipe 240a suction-holds the central portion of the upper wafer W1. The peripheral suction pipe 240c suction-holds the peripheral portion W1e of the upper wafer W1. The intermediate suction pipe 240b suction-holds the intermediate portion between the central portion and the peripheral portion W1e of the upper wafer W1.

A vacuum pump 241a is connected to the central suction pipe 240a, a vacuum pump 241b is connected to the intermediate suction pipe 240b, and a vacuum pump 241c is connected to the peripheral suction pipe 240c. In this way, the upper chuck 230 is configured to be able to set the vacuum suction of the upper wafer W1 for each of the regions 230a, 230b, and 230c.

In addition, the bonding device 41 can determine whether the upper wafer W1 and the lower wafer W2 are bonded at each position by monitoring the suction status of the suction pipes at each position. For example, when the vacuum pump 241b is operating, if the pressure inside the intermediate suction pipe 240b changes from negative to atmospheric pressure, it can be considered that the upper wafer W1 has separated from the intermediate suction pipe 240b.

Then, the control unit 5 can determine that the upper wafer W1 has been bonded to the lower wafer W2 at the middle of the wafer W because the upper wafer W1 has been separated from the middle suction pipe 240b.

A through hole 243 is formed in the center of the upper chuck 230, penetrating the upper chuck 230 in the thickness direction. The center of the upper chuck 230 corresponds to the center W1c of the upper wafer W1 that is held by suction on the upper chuck 230. The pressure pin 253 of the striker 250 is inserted into the through hole 243.

The striker 250 is provided on the upper surface of the upper chuck 230 and presses the center W1c of the upper wafer W1 with a pressing pin 253. The pressing pin 253 is provided so as to be movable linearly along a vertical axis by a cylinder part 251 and an actuator part 252, and presses the opposing substrate (the upper wafer W1 in this embodiment) with its tip.

Specifically, the pressure pin 253 serves as a starter that first brings the center W1c of the upper wafer W1 and the center W2c of the lower wafer W2 into contact when bonding the upper wafer W1 and the lower wafer W2, as described below.

The lower chuck 231 is generally disk-shaped and is partitioned into multiple regions, for example, two regions 231a and 231b. These regions 231a and 231b are provided in this order from the center of the lower chuck 231 toward the periphery. Region 231a has a circular shape in a plan view, and region 231b has an annular shape in a plan view.

As shown in FIG. 7, suction pipes 260a, 260b for suctioning and holding the lower wafer W2 are provided independently in each of the regions 231a, 231b. Different vacuum pumps 261a, 261b are connected to each of the suction pipes 260a, 260b. In this way, the lower chuck 231 is configured to be able to set the vacuum suction of the lower wafer W2 for each of the regions 231a, 231b.

Stopper members 263 are provided at multiple locations, for example five locations, on the periphery of the lower chuck 231 to prevent the upper wafer W1, the lower wafer W2, and the laminated wafer T from jumping out or slipping off the lower chuck 231.

The bonding device 41 also includes a suction and discharge mechanism 270 that sucks in the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other, and further discharges low-humidity gas between the upper wafer W1 and the lower wafer W2 facing each other.

The suction and discharge mechanism 270 has a main body 271, a gas suction section 272 (see FIG. 8), and a gas discharge section 273. The main body 271 has, for example, a circular ring shape and is disposed so as to surround the peripheral portion of the upper chuck 230.

The gas suction unit 272 sucks in the atmosphere between the upper wafer W1 and the lower wafer W2 that face each other. Details of the gas suction unit 272 will be described later.

The gas discharge unit 273 discharges low-humidity gas between the upper wafer W1 and the lower wafer W2 facing each other from a plurality of discharge ports 273d (see FIG. 8) formed in the main body 271. In the embodiment, the low-humidity gas is a gas having a lower humidity than the atmosphere in the processing vessel 190, for example, an inert gas (such as nitrogen gas) having a lower humidity than the atmosphere in the processing vessel 190.

The gas discharge section 273 has a gas supply source 273a, a valve 273b, a flow regulator 273c, and a number of discharge ports 273d. The low humidity gas supplied from the gas supply source 273a is flow-controlled by the valve 273b and the flow regulator 273c, and is discharged from the discharge ports 273d.

<Configuration of suction and discharge mechanism>
Next, a detailed configuration of the suction and discharge mechanism 270 will be described with reference to Fig. 8. Fig. 8 is an enlarged side view showing the configuration of the suction and discharge mechanism 270 according to the embodiment. Fig. 8 is an enlarged cross-sectional view showing a case where the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 are brought close to each other by a preset distance and the lower chuck 231 is located at the home position.

As described above, the suction and discharge mechanism 270 has a main body 271, a gas suction section 272, and a gas discharge section 273. The suction and discharge mechanism 270 further has a support section 274, a sealing section 275, and a sensor section 276.

The main body 271 has, for example, a circular ring shape and is positioned to surround the peripheral edge of the upper chuck 230 while maintaining a given distance from the peripheral edge of the upper chuck 230.

The gas suction section 272 has a plurality of suction ports 272a, a valve 272b, and a suction mechanism 272c. The plurality of suction ports 272a are formed on the inner peripheral surface of the main body section 271 at equal intervals in the circumferential direction.

The suction mechanism 272c is, for example, a pump, and is connected to the multiple suction ports 272a via the valve 272b. The control unit 5 can operate the valve 272b and the suction mechanism 272c to suck the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other through the multiple suction ports 272a.

The gas discharge section 273 has a gas supply source 273a (see FIG. 7), a valve 273b, a flow rate regulator 273c (see FIG. 7), and a plurality of discharge ports 273d. The plurality of discharge ports 273d are formed on the inner peripheral surface of the main body section 271 at equal intervals in the circumferential direction. In the example of FIG. 8, the discharge ports 273d and the suction port 272a are disposed close to each other.

The control unit 5 can discharge low-humidity gas between the upper wafer W1 and the lower wafer W2 facing each other from the multiple discharge ports 273d by operating the valve 273b and the flow rate regulator 273c.

The support portion 274 supports the main body portion 271 on the upper chuck 230. The sealing portion 275 has, for example, a circular ring shape and is attached to the underside of the main body portion 271. The sealing portion 275 is made of a material that is elastically deformable.

Here, in the bonding apparatus 41 according to the embodiment, when the lower wafer W2 held by the lower chuck 231 is located at the home position relative to the upper wafer W1 held by the upper chuck 230, the upper wafer W1 and the lower wafer W2 are sealed from the outside.

In other words, when the lower wafer W2 is located at the home position, the upper wafer W1 and the lower wafer W2 are shielded from the outside (the atmosphere inside the processing vessel 190 (see FIG. 5)) by the upper chuck 230, the lower chuck 231, the main body 271, the support portion 274, and the sealing portion 275.

In addition, since the sealing portion 275 is elastically deformable, when the upper wafer W1 and the lower wafer W2 are brought even closer to each other from the state shown in FIG. 8 and the lower wafer W2 is positioned at the bond position, the sealing portion 275 does not become an obstructing factor.

In this disclosure, the bond position refers to the position of the lower chuck 231 when the process of pressing the center W1c of the upper wafer W1 with the striker 250 is performed. When the lower chuck 231 is in the bond position, the gap between the upper wafer W1 and the lower wafer W2 is, for example, about 50 μm.

In addition, in this disclosure, the home position is a position where the lower chuck 231 is temporarily placed on standby when starting the process of placing the lower chuck 231 at the bond position. When the lower chuck 231 is in the home position, the horizontal position adjustment of the upper wafer W1 and the lower wafer W2 is complete, and the distance between the upper wafer W1 and the lower wafer W2 is, for example, approximately 80 μm to 100 μm.

The sensor unit 276 is provided adjacent to at least one of the upper wafer W1 and the lower wafer W2 (upper wafer W1 in the figure). The sensor unit 276 is provided, for example, at a position in the upper chuck 230 adjacent to the upper wafer W1. The sensor unit 276 has a humidity sensor, etc.

The control unit 5 can measure the humidity of the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other by operating the sensor unit 276.

<Processing performed by the joining system>
Next, the details of the processes executed by the bonding system 1 according to the embodiment will be described with reference to Fig. 9 to Fig. 11. Note that the various processes described below are executed based on the control by the control unit 5 of the control device 4.

Figure 9 is a flowchart showing a part of the processing procedure executed by the bonding system 1 according to the embodiment. First, a cassette C1 containing multiple upper wafers W1, a cassette C2 containing multiple lower wafers W2, and an empty cassette C3 are placed on a given placement plate 11 of the loading/unloading station 2.

Then, the upper wafer W1 is removed from the cassette C1 by the 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 W1 is transported by the transport device 61 to the surface modification device 30 in the first processing block G1. At this time, the gate valve 72 is open, and the inside of the processing vessel 70 is exposed to atmospheric pressure. In the surface modification device 30, the processing gas is excited to become plasma and ionized in a given reduced pressure atmosphere.

The ions thus generated are irradiated onto the bonding surface W1j of the upper wafer W1, and the bonding surface W1j is plasma-treated. As a result, dangling bonds of silicon atoms are formed on the outermost surface of the bonding surface W1j, and the bonding surface W1j of the upper wafer W1 is modified (step S101).

Next, the upper wafer W1 is transported by the 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 W1 while rotating the upper wafer W1 held by the spin chuck.

The supplied pure water then diffuses over the bonding surface W1j of the upper wafer W1. As a result, in the surface modification device 30, OH groups (silanol groups) are attached to the dangling bonds of silicon atoms on the modified bonding surface W1j of the upper wafer W1, making the bonding surface W1j hydrophilic (step S102). The pure water also cleans the bonding surface W1j of the upper wafer W1.

Next, the upper wafer W1 is transferred by the transfer device 61 to the bonding device 41 in the second processing block G2. The upper wafer W1 that has been transferred to the bonding device 41 is transferred to the position adjustment mechanism 210 via the transition 200. The horizontal orientation of the upper wafer W1 is then adjusted by the position adjustment mechanism 210 (step S103).

Then, the upper wafer W1 is transferred from the position adjustment mechanism 210 to the inversion mechanism 220. Next, in the transfer region T1, the inversion mechanism 220 is operated to invert the front and back surfaces of the upper wafer W1 (step S104). That is, the bonding surface W1j of the upper wafer W1 is directed downward.

Then, the inversion mechanism 220 rotates and moves to below the upper chuck 230. Then, the upper wafer W1 is transferred from the inversion mechanism 220 to the upper chuck 230. The upper wafer W1 is held by suction at its non-bonding surface W1n on the upper chuck 230 (step S105).

While the upper wafer W1 is being processed in the above-mentioned steps S101 to S105, the lower wafer W2 is being processed. First, the lower wafer W2 is removed from the cassette C2 by the transfer device 22 and transferred to the transition device 50 in the processing station 3.

Next, the lower wafer W2 is transferred by the transfer device 61 to the surface modification device 30, where the bonding surface W2j of the lower wafer W2 is modified (step S106). Note that step S106 is the same process as step S101 described above.

Then, the lower wafer W2 is transferred by the transfer device 61 to the surface hydrophilization device 40, where the bonding surface W2j of the lower wafer W2 is hydrophilized (step S107). Note that step S107 is the same process as step S102 described above.

Then, the lower wafer W2 is transported to the bonding device 41 by the transport device 61. The lower wafer W2 that has been transported to the bonding device 41 is transported to the position adjustment mechanism 210 via the transition 200. The horizontal orientation of the lower wafer W2 is then adjusted by the position adjustment mechanism 210 (step S108).

Then, the lower wafer W2 is transferred to the lower chuck 231 and adsorbed and held by the lower chuck 231 (step S109). The lower wafer W2 has its non-bonding surface W2n adsorbed and held by the lower chuck 231 with the notch facing in a predetermined direction.

Next, the horizontal positions of the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 are adjusted (step S110).

Next, the lower chuck 231 is moved vertically upward by the first lower chuck moving part 310 to adjust the vertical positions of the upper chuck 230 and the lower chuck 231. This adjusts the vertical positions of the upper wafer W1 held by the upper chuck 230 and the lower wafer W2 held by the lower chuck 231 (step S111).

At this time, the distance between the bonding surface W2j of the lower wafer W2 and the bonding surface W1j of the upper wafer W1 is a preset distance, for example, 80 μm to 100 μm.

Then, a bonding process is performed to bond the upper wafer W1 and the lower wafer W2 with a given gap maintained (step S112), and the bonding process in the bonding device 41 is completed.

Figure 10 is a timing chart showing the operation of each part in the bonding process according to the embodiment. Note that Figure 10 shows the timing chart from the point in time when the above-mentioned step S110 (adjusting the horizontal positions of the upper wafer W1 and the lower wafer W2) is completed.

First, from time T11, the control unit 5 controls the gas suction unit 272 to suction the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other.

In addition, from time T11, the control unit 5 repeats the operation of raising the lower chuck 231 from the home position to the bond position and the operation of lowering the lower chuck 231 from the bond position to the home position. In other words, from time T11, the control unit 5 expands or contracts the gap between the upper wafer W1 and the lower wafer W2.

In this way, by expanding and contracting the gap between the upper wafer W1 and the lower wafer W2, the control unit 5 can efficiently suck in the atmosphere between the upper wafer W1 and the lower wafer W2.

Then, at time T12, a given time after time T11, the control unit 5 stops the gas suction unit 272 and operates the gas discharge unit 273 to discharge low-humidity gas between the upper wafer W1 and the lower wafer W2. This allows the control unit 5 to replace the atmosphere between the upper wafer W1 and the lower wafer W2 with a low-humidity atmosphere.

The control unit 5 also continues the operation of expanding or contracting the gap between the upper wafer W1 and the lower wafer W2 even after time T12. This allows the control unit 5 to efficiently replace the atmosphere between the upper wafer W1 and the lower wafer W2 with a low humidity atmosphere.

Next, at time T13 when the humidity between the upper wafer W1 and the lower wafer W2 reaches a given humidity, the control unit 5 stops the gas discharge unit 273 and raises the lower chuck 231 to the bond position.

The control unit 5 can obtain information from the sensor unit 276 as to whether or not the humidity between the upper wafer W1 and the lower wafer W2 has reached a given humidity. That is, the control unit 5 ends the process of expanding or contracting the gap between the upper wafer W1 and the lower wafer W2 based on the detection result of the sensor unit 276.

Then, when the lower chuck 231 reaches the bond position, the control unit 5 lowers the pressing pin 253 of the striker 250. As a result, the striker 250 presses down the center W1c of the upper wafer W1, pressing the center W1c of the upper wafer W1 and the center W2c of the lower wafer W2 with a given force.

This starts bonding between the center W1c of the pressed upper wafer W1 and the center W2c of the pressed lower wafer W2. Specifically, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 have been modified in steps S101 and S106, respectively, van der Waals forces (intermolecular forces) are first generated between the bonding surfaces W1j and W2j, and the bonding surfaces W1j and W2j are bonded together.

Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 have been made hydrophilic in steps S102 and S107, respectively, the OH groups between the bonding surfaces W1j and W2j form hydrogen bonds, and the bonding surfaces W1j and W2j are firmly bonded to each other.

Then, the bonding area between the upper wafer W1 and the lower wafer W2 expands from the center W1c of the upper wafer W1 and the center W2c of the lower wafer W2 toward the outer periphery. That is, the bonding between the bonding surfaces W1j and W2j described above due to van der Waals forces and hydrogen bonds expands sequentially from the centers W1c and W2c toward the outer periphery.

First, at time T13, the striker 250 presses down the center W1c of the upper wafer W1, thereby separating the upper wafer W1 from the center suction pipe 240a. That is, at time T13, the upper wafer W1 is bonded to the lower wafer W2 at the center of the wafer W.

Then, as a result of the bonding area gradually expanding toward the outer periphery, at time T14, the upper wafer W1 is separated from the peripheral suction pipe 240c. At this point, the bonding area has reached the peripheral portions W1e and W2e of the wafer W, so that the upper wafer W1 and the lower wafer W2 are bonded together over their entire surfaces, forming an overlapped wafer T.

Next, at time T15, which is a given time that has elapsed since time T14, the control unit 5 lowers the position of the lower chuck 231 from the bond position to the home position. Then, at time T16, the control unit 5 lowers the lower chuck 231 to the home position, thereby enabling the control unit 5 to remove the laminated wafer T that is held by suction on the lower chuck 231 from the bonding device 41.

In the embodiment, the various processes described above can improve the bonding quality of the laminated wafer T. The reasons for this are described below.

Figure 11 is a diagram for explaining the details of the bonding process according to the embodiment. As shown in (a) of Figure 11, the upper wafer W1 and the lower wafer W2 are arranged to face each other, and then, as shown in (b) of Figure 11, low-humidity gas is discharged from the gas discharge portion 273 between the upper wafer W1 and the lower wafer W2.

As a result, the space between the upper wafer W1 and the lower wafer W2 is replaced with a low-humidity atmosphere, causing the moisture adsorbed on the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 to evaporate, as shown in FIG. 11(c).

In the embodiment, less moisture is adsorbed to the bonding surfaces W1j and W2j, which reduces hydrogen bonds on the bonding surfaces W1j and W2j, and therefore the speed at which the bonding area advances when bonding the upper wafer W1 and the lower wafer W2 can be slowed down.

As a result, in this embodiment, it is possible to reduce edge voids that occur in the laminated wafer T. The reason why such edge voids can be reduced is explained below.

When the upper wafer W1 and the lower wafer W2 are bonded together, the central portions W1c and W2c are bonded by intermolecular forces to form a bonded region, and then a wave (so-called bonding wave) is generated as the bonded region expands toward the peripheral portions W1e and W2e of the wafer W.

Here, one of the causes of edge voids is thought to be a sudden change in pressure at the peripheral portions W1e and W2e of the wafer W when the bonding wave reaches these peripheral portions W1e and W2e of the wafer W.

This is because such a sudden pressure fluctuation causes a sudden drop in the ambient temperature near the peripheral portions W1e and W2e, causing condensation to form on the peripheral portion W1e of the upper wafer W1 and the peripheral portion W2e of the lower wafer W2, resulting in the formation of edge voids.

On the other hand, in the embodiment, the speed of progression of the bonding area when bonding the upper wafer W1 and the lower wafer W2 is slowed down, which makes it possible to suppress sudden pressure fluctuations near the peripheral portions W1e and W2e of the wafer W.

As a result, the control unit 5 can prevent a sudden drop in temperature at the peripheral portions W1e and W2e of the wafer W, thereby preventing condensation from occurring at the peripheral portion W1e of the upper wafer W1 and the peripheral portion W2e of the lower wafer W2.

Therefore, according to the embodiment, it is possible to reduce edge voids that occur in the laminated wafer T, thereby improving the bonding quality of the laminated wafer T.

In addition, in the embodiment, prior to the process of discharging low-humidity gas between the upper wafer W1 and the lower wafer W2 by the gas discharge unit 273, it is preferable to suck the atmosphere between the upper wafer W1 and the lower wafer W2 by the gas suction unit 272.

This allows the control unit 5 to efficiently inject low-humidity gas into the gap between the upper wafer W1 and the lower wafer W2, which is relatively narrow and where replacement with low-humidity gas is difficult to progress in this state.

Therefore, according to the embodiment, the overall bonding process time can be shortened, and the laminated wafer T can be manufactured efficiently.

In addition, in the embodiment, when the lower wafer W2 held by the lower chuck 231 is located at the home position, the upper wafer W1 and the lower wafer W2 may be sealed from the outside by a sealing portion 275 made of an elastically deformable material.

As a result, the control unit 5 can create a negative pressure in the gap between the upper wafer W1 and the lower wafer W2 when the gas suction unit 272 suctions the atmosphere between the upper wafer W1 and the lower wafer W2. In other words, the control unit 5 can more efficiently inject low-humidity gas into the relatively narrow gap between the upper wafer W1 and the lower wafer W2.

Therefore, according to the embodiment, the overall bonding process time can be further shortened, and the laminated wafer T can be manufactured more efficiently.

In addition, in the embodiment, when the suction/discharge mechanism 270 is used to suction the atmosphere between the upper wafer W1 and the lower wafer W2 or to discharge gas between the upper wafer W1 and the lower wafer W2, it is preferable to expand or contract the gap between the upper wafer W1 and the lower wafer W2.

This allows the control unit 5 to obtain a pumping effect that circulates the atmosphere between the upper wafer W1 and the lower wafer W2, allowing the low-humidity gas to be more efficiently injected into the gap between the upper wafer W1 and the lower wafer W2, which is relatively narrow.

Therefore, according to the embodiment, the overall bonding process time can be further shortened, and the laminated wafer T can be manufactured more efficiently.

In the above embodiment, the control unit 5 performs a process to expand or contract the gap between the upper wafer W1 and the lower wafer W2 for the entire period from time T11 to time T13, but this expansion or contraction process does not necessarily have to be performed for the entire period from time T11 to time T13.

For example, the control unit 5 may perform a process to expand or contract the gap between the upper wafer W1 and the lower wafer W2 during a portion of the period from time T11 to time T13. For example, the control unit 5 may perform a process to expand or contract the gap between the upper wafer W1 and the lower wafer W2 during the period from time T11 to time T12, or may perform a process to expand or contract the gap between the upper wafer W1 and the lower wafer W2 during the period from time T12 to time T13.

In addition, the control unit 5 does not need to perform a process to expand or contract the gap between the upper wafer W1 and the lower wafer W2 between time T11 and time T13.

In the above case, during the period when the expansion/contraction process is not being performed, the control unit 5 may operate the suction/discharge mechanism 270 while maintaining the position of the lower chuck 231 in the home position.

This allows the gap between the upper wafer W1 and the lower wafer W2 to be wider than when the lower chuck 231 is in the bond position, so replacement with low humidity gas can be continued even if this expansion/contraction process is not performed.

In addition, in the above embodiment, the striker 250 performs the pressing process on the upper wafer W1 based on the humidity information between the upper wafer W1 and the lower wafer W2 obtained from the sensor unit 276, but the method of controlling the striker 250 in the embodiment is not limited to this example.

For example, when the operation time of the suction and discharge mechanism 270 (corresponding to times T11 to T13) reaches a given time, the control unit 5 may determine that the desired low humidity has been reached between the upper wafer W1 and the lower wafer W2, and may perform a pressing process on the upper wafer W1 using the striker 250. This given time may be stored in advance in the memory unit 6.

In addition, in the above embodiment, an example is shown in which a low-humidity gas having a lower humidity than the atmosphere inside the processing vessel 190 is discharged from the gas discharge portion 273 of the suction and discharge mechanism 270, but a high-humidity gas having a higher humidity than the atmosphere inside the processing vessel 190 may also be discharged from the gas discharge portion 273.

This allows for more hydrogen bonds to be formed on the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 immediately before the bonding process, thereby reducing distortion of the laminated wafer T, for example.

That is, in the embodiment, a gas having a humidity different from that of the atmosphere inside the processing vessel 190 (low humidity gas or high humidity gas) may be discharged from the gas discharge portion 273 of the suction and discharge mechanism 270.

This allows for various control over the hydrogen bonding state of the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 immediately before the bonding process, thereby improving the bonding quality of the laminated wafer T in various ways.

<Modification>
Next, a modified example of the embodiment will be described with reference to Fig. 12 to Fig. 14. Fig. 12 is a timing chart showing the operation of each part in the bonding process according to the modified example of the embodiment. Fig. 12 shows the timing chart from the point in time when the above-mentioned step S110 (adjustment of the horizontal positions of the upper wafer W1 and the lower wafer W2) is completed.

First, from time T21, the control unit 5 controls the gas suction unit 272 to suck in the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other, and operates the gas discharge unit 273 to discharge low-humidity gas between the upper wafer W1 and the lower wafer W2.

That is, in this modified example, from time T21, the control unit 5 performs a process of sucking the atmosphere from between the upper wafer W1 and the lower wafer W2 and a process of ejecting low-humidity gas between the upper wafer W1 and the lower wafer W2 in parallel.

This allows the control unit 5 to more efficiently inject low-humidity gas into the gap between the upper wafer W1 and the lower wafer W2, which is relatively narrow. Therefore, according to the modified example, the overall bonding process time can be further shortened, and the laminated wafer T can be manufactured more efficiently.

In addition, from time T21, the control unit 5 repeats the operation of raising the lower chuck 231 from the home position to the bond position and the operation of lowering the lower chuck 231 from the bond position to the home position. In other words, from time T21, the control unit 5 expands or contracts the gap between the upper wafer W1 and the lower wafer W2.

In this way, by expanding or contracting the gap between the upper wafer W1 and the lower wafer W2, the control unit 5 can more efficiently replace the atmosphere between the upper wafer W1 and the lower wafer W2 with low humidity gas.

Next, at time T22 when the humidity between the upper wafer W1 and the lower wafer W2 reaches a given humidity, the control unit 5 stops the gas suction unit 272 and the gas discharge unit 273 and raises the lower chuck 231 to the bond position.

When the operation time of the suction and discharge mechanism 270 reaches a given time, the control unit 5 may determine that the desired low humidity has been reached between the upper wafer W1 and the lower wafer W2, and may perform the next process (pressing the upper wafer W1 with the striker 250).

Then, when the lower chuck 231 reaches the bond position, the control unit 5 lowers the pressing pin 253 of the striker 250. As a result, the striker 250 presses down the center W1c of the upper wafer W1, pressing the center W1c of the upper wafer W1 and the center W2c of the lower wafer W2 with a given force.

This starts bonding between the center W1c of the pressed upper wafer W1 and the center W2c of the pressed lower wafer W2. The following process is the same as in the embodiment, so a detailed description is omitted.

In addition, in this modified example, since the process of sucking in the atmosphere and the process of discharging the low humidity gas are performed in parallel, it is preferable that the suction port 272a of the gas suction unit 272 and the discharge port 273d of the gas discharge unit 273 are arranged at a distance from each other.

This prevents the low-humidity gas discharged from the discharge port 273d from being immediately sucked in through the nearby suction port 272a, preventing the replacement with low-humidity gas from progressing.

For example, as shown in FIG. 13, in a plan view, a plurality of suction ports 272a may be arranged in a group in the circumferential direction, and a plurality of discharge ports 273d may be arranged in a group in the circumferential direction. Also, as shown in FIG. 14, in a plan view, the suction ports 272a and the discharge ports 273d may be arranged alternately in the circumferential direction.

Figure 13 is a top view showing an example of the arrangement of the gas suction section 272 and the gas discharge section 273 according to a modified embodiment, and Figure 14 is a top view showing another example of the arrangement of the gas suction section 272 and the gas discharge section 273 according to a modified embodiment.

This arrangement allows a flow of low-humidity gas to be formed throughout the entire space between the upper wafer W1 and the lower wafer W2, allowing the control unit 5 to more efficiently replace the atmosphere between the upper wafer W1 and the lower wafer W2 with low-humidity gas.

In addition, in the modified example, the arrangement of the suction port 272a and the discharge port 273d is not limited to the example in FIG. 13 and the example in FIG. 14.

The bonding device 41 according to the embodiment includes a first holding part (upper chuck 230), a second holding part (lower chuck 231), a striker 250, a processing vessel 190, a gas discharge part 273, and a control part 5. The first holding part (upper chuck 230) suction-holds the first substrate (upper wafer W1) from above. The second holding part (lower chuck 231) suction-holds the second substrate (lower wafer W2) from below. The striker 250 presses the center part W1c of the first substrate (upper wafer W1) from above to contact the second substrate (lower wafer W2). The processing vessel 190 accommodates the first holding part (upper chuck 230), the second holding part (lower chuck 231), and the striker 250. The gas discharge part 273 discharges a gas having a humidity different from that of the atmosphere in the processing vessel 190. The control unit 5 controls each unit. The control unit 5 also ejects gas from the gas ejection unit 273 between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) just before the first substrate (upper wafer W1) facing the second substrate (lower wafer W2) is pressed by the striker 250. This improves the bonding quality of the overlapped wafer T.

In addition, in the bonding apparatus 41 according to the embodiment, the gas discharge unit 273 discharges a low-humidity gas having a lower humidity than the atmosphere inside the processing vessel 190 between the first substrate (upper wafer W1) and the second substrate (lower wafer W2). This makes it possible to reduce edge voids that occur in the overlapped wafer T.

In addition, in the bonding apparatus 41 according to the embodiment, the control unit 5 expands or contracts the gap between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) just before the first substrate (upper wafer W1) facing the second substrate (lower wafer W2) is pressed by the striker 250. This allows the laminated wafer T to be manufactured more efficiently.

The bonding apparatus 41 according to the embodiment further includes a sensor unit 276 that detects the humidity of the atmosphere between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) facing each other. The control unit 5 also terminates the process of expanding or contracting the gap between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) based on the detection result of the sensor unit 276. This allows the pressing process to be performed after the humidity between the upper wafer W1 and the lower wafer W2 has reached a given humidity level, thereby further improving the bonding quality of the overlapped wafers T.

In addition, in the bonding apparatus 41 according to the embodiment, the control unit 5 discharges gas from the gas discharge unit 273 between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) when the position of the second holding unit (lower chuck 231) is in the bond position. The bond position is the position of the second holding unit (lower chuck 231) when the first substrate (upper wafer W1) facing the second substrate (lower wafer W2) is pressed by the striker 250. This makes it possible to reduce edge voids that occur in the overlapped wafer T.

In addition, the bonding apparatus 41 according to the embodiment further includes a gas suction section 272 that sucks in the atmosphere between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) that face each other. This allows the laminated wafer T to be manufactured efficiently.

In addition, in the bonding apparatus 41 according to the embodiment, the control unit 5 causes the gas suction unit 272 to suck in the atmosphere between the first substrate (upper wafer W1) and the second substrate (lower wafer W2), and then discharges gas from the gas discharge unit 273. This allows the laminated wafer T to be manufactured efficiently.

In addition, in the bonding apparatus 41 according to the embodiment, the control unit 5 discharges gas from the gas discharge unit 273 in parallel with the operation of sucking the atmosphere between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) with the gas suction unit 272. This allows the laminated wafer T to be manufactured more efficiently.

The bonding apparatus 41 according to the embodiment further includes a sensor unit 276 that detects the humidity of the atmosphere between the first substrate (upper wafer W1) and the second substrate (lower wafer W2) facing each other. Based on the detection result of the sensor unit 276, the control unit 5 presses the first substrate (upper wafer W1) facing the second substrate (lower wafer W2) with the striker 250. This allows the pressing process to be performed after the humidity between the upper wafer W1 and the lower wafer W2 reaches a given humidity level, thereby further improving the bonding quality of the overlapped wafer T.

<Details of the joining process>
Next, details of the joining process performed by the joining device 41 according to the embodiment will be described with reference to Fig. 15. Fig. 15 is a flowchart showing the procedure of the joining process performed by the joining device 41 according to the embodiment.

Note that FIG. 15 shows a flowchart from the point where step S110 (adjusting the horizontal positions of the upper wafer W1 and the lower wafer W2) shown in FIG. 9 is completed.

First, the control unit 5 controls the bonding device 41 to move the lower chuck 231 to the home position (step S201). Next, the control unit 5 controls the bonding device 41 to repeat the operation of raising the lower chuck 231 from the home position to the bond position and the operation of lowering the lower chuck 231 from the bond position to the home position. That is, the control unit 5 expands or contracts the gap between the upper wafer W1 and the lower wafer W2 (step S202).

In parallel with the processing of step S202, the control unit 5 controls the gas suction unit 272 to suction the atmosphere between the upper wafer W1 and the lower wafer W2 facing each other (step S203).

Next, the control unit 5 controls the gas suction unit 272 to stop suction of the atmosphere between the upper wafer W1 and the lower wafer W2 (step S204). Then, the control unit 5 controls the gas discharge unit 273 to discharge gas (low humidity gas or high humidity gas) between the upper wafer W1 and the lower wafer W2 facing each other (step S205).

Next, the control unit 5 determines whether or not a given humidity has been reached between the upper wafer W1 and the lower wafer W2 (step S206). If the given humidity has not been reached between the upper wafer W1 and the lower wafer W2 (step S206, No), the control unit 5 repeats the process of step S206.

On the other hand, if the given humidity has been reached between the upper wafer W1 and the lower wafer W2 (step S206, Yes), the control unit 5 controls the gas discharge unit 273 to stop discharging gas between the upper wafer W1 and the lower wafer W2 (step S207).

Then, the control unit 5 controls the bonding device 41 to move the lower chuck 231 to the bonding position (step S208). Finally, the control unit 5 presses the center of the upper wafer W1 with the striker 250 (step S209), completing the series of processes.

The bonding method according to the embodiment includes a first holding step (step S105), a second holding step (step S109), a substrate facing step (step S110), a gas ejection step (step S205), and a pressing step (step S209). The first holding step (step S105) uses a first holding part (upper chuck 230) that adsorbs and holds the first substrate (upper wafer W1) from above, and adsorbs and holds the first substrate (upper wafer W1) from above. The second holding step (step S109) uses a second holding part (lower chuck 231) that adsorbs and holds the second substrate (lower wafer W2) from below, and adsorbs and holds the second substrate (lower wafer W2) from below. In the substrate facing process (step S110), the first substrate (upper wafer W1) held by the first holding part (upper chuck 230) and the second substrate (lower wafer W2) held by the second holding part (lower chuck 231) are made to face each other. In the gas discharge process (step S205), a gas having a humidity different from that of the atmosphere in the processing vessel 190 that contains the first holding part (upper chuck 230) and the second holding part (lower chuck 231) is discharged between the first substrate (upper wafer W1) and the second substrate (lower wafer W2). In the pressing process (step S209), the striker 250 presses the center part W1c of the first substrate (upper wafer W1) from above immediately after the gas discharge process (step S205). This improves the bonding quality of the overlapped wafer T.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

REFERENCE SIGNS LIST 1 Bonding system 5 Control unit 41 Bonding device 190 Processing vessel 230 Upper chuck (an example of a first holding unit)
231 Lower chuck (an example of a second holding portion)
250 striker 270 suction/discharge mechanism 272 gas suction section 273 gas discharge section 276 sensor section W1 upper wafer (an example of a first substrate)
W2 Lower wafer (an example of a second substrate)

Claims (9)

a first holding portion that suction-holds the first substrate from above;
a second holding portion that suction-holds the second substrate from below;
a striker that presses a center portion of the first substrate from above to bring the center portion into contact with the second substrate;
a processing vessel that accommodates the first holding part, the second holding part, and the striker;
a gas discharge unit that discharges a gas having a humidity different from that of the atmosphere in the processing vessel;
a sensor unit for detecting the humidity of an atmosphere between the first substrate and the second substrate facing each other;
A control unit for controlling each unit;
Equipped with
The control unit is
immediately before the first substrate facing the second substrate is pressed by the striker, the gas is discharged from the gas discharge portion between the first substrate and the second substrate;
Immediately before the first substrate facing the second substrate is pressed by the striker, the interval between the first substrate and the second substrate is expanded or contracted;
The process of expanding or contracting the gap between the first substrate and the second substrate is terminated based on the detection result of the sensor unit.
Joining device. The bonding apparatus according to claim 1 , wherein the gas discharge unit discharges a low-humidity gas having a humidity lower than that of an atmosphere in the processing chamber between the first substrate and the second substrate. 3. The bonding apparatus according to claim 1, wherein the control unit ejects the gas from the gas ejection unit between the first substrate and the second substrate when the second holding unit is in a bonding position when the first substrate facing the second substrate is pressed by the striker. The bonding apparatus according to claim 1 , further comprising a gas suction unit that sucks in an atmosphere between the first substrate and the second substrate facing each other. The bonding apparatus according to claim 4 , wherein the control unit causes the gas suction unit to suck in an atmosphere between the first substrate and the second substrate, and then discharges the gas from the gas discharge unit. The bonding apparatus according to claim 4 , wherein the control unit discharges the gas from the gas discharge unit in parallel with an operation of the gas suction unit to suck in the atmosphere between the first substrate and the second substrate. a first holding portion that suction-holds the first substrate from above;
a second holding portion that suction-holds the second substrate from below;
a striker that presses a center portion of the first substrate from above to bring the center portion into contact with the second substrate;
a processing vessel that accommodates the first holding part, the second holding part, and the striker;
a gas discharge unit that discharges a gas having a humidity different from that of the atmosphere in the processing vessel;
a sensor unit for detecting the humidity of an atmosphere between the first substrate and the second substrate facing each other ;
A control unit for controlling each unit;
Equipped with
The control unit is
immediately before the first substrate facing the second substrate is pressed by the striker, the gas is discharged from the gas discharge portion between the first substrate and the second substrate;
The first substrate facing the second substrate is pressed by the striker based on a detection result of the sensor unit.
Joining device. a first holding step of suction-holding the first substrate from above using a first holding unit that suction-holds the first substrate from above;
a second holding step of suction-holding the second substrate from below using a second holding unit that suction-holds the second substrate from below;
a substrate facing step of aligning the first substrate held by the first holding portion and the second substrate held by the second holding portion to face each other;
a gas discharge step of discharging a gas having a humidity different from that of an atmosphere in a processing vessel accommodating the first holding unit and the second holding unit between the first substrate and the second substrate;
an expansion/contraction step of expanding/contracting a gap between the first substrate and the second substrate in parallel with the gas discharge step;
a pressing step of pressing a center portion of the first substrate from above with a striker immediately after the gas discharge step and the expansion/contraction step ;
Including,
The expansion/contraction step is a step of expanding/contracting a space between the first substrate and the second substrate based on the humidity of the atmosphere between the first substrate and the second substrate facing each other.
Joining method. a first holding step of suction-holding the first substrate from above using a first holding unit that suction-holds the first substrate from above;
a second holding step of suction-holding the second substrate from below using a second holding unit that suction-holds the second substrate from below;
a substrate facing step of aligning the first substrate held by the first holding portion and the second substrate held by the second holding portion to face each other;
a gas discharge step of discharging a gas having a humidity different from that of an atmosphere in a processing vessel accommodating the first holding unit and the second holding unit between the first substrate and the second substrate;
a pressing step of pressing a central portion of the first substrate from above with a striker immediately after the gas discharge step;
Including,
The pressing step starts a step of pressing the center portion of the first substrate from above with the striker based on the humidity of the atmosphere between the first substrate and the second substrate facing each other.
Joining method .

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