Bonding system and bonding method

Abstract

To provide a technique capable of improving the bonding quality of a polymerization substrate.SOLUTION: A bonding system comprises a surface reforming device and a bonding device. The surface reforming device reforms surfaces of a first substrate and a second substrate. The bonding device bonds together, by intermolecular force, the first substrate and the second substrate thus reformed by the surface reforming device. The surface reforming device has a surface reforming unit, a conveyance unit, and a processing gas supply unit. The surface reforming unit reforms the surfaces of the first substrate and the second substrate one by one. In a condition separated from an external atmosphere, the conveyance unit conveys the first substrate or the second substrate between the outside and the surface reforming unit. The processing gas supply unit supplies moisture-containing processing gas into the conveyance unit.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present disclosure relates to bonding systems and methods. [Background technology]

[0002] Conventionally, a 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 by van der Waals forces and hydrogen bonds (intermolecular forces) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-073455 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can improve the bonding quality of laminated substrates. [Means for solving the problem]

[0005] A bonding system according to an embodiment of the present disclosure includes a surface modification device and a bonding device. The surface modification device modifies the surfaces of a first substrate and a second substrate. The bonding device bonds the first substrate and the second substrate modified by the surface modification device by intermolecular forces. The surface modification device also includes a surface modification unit, a transport unit, and a processing gas supply unit. The surface modification unit modifies the surfaces of the first substrate and the second substrate one by one. The transport unit transports the first substrate or the second substrate between an outside and the surface modification unit in a state isolated from the outside atmosphere. The processing gas supply unit supplies a processing gas containing moisture to the inside of the transport unit. Effect of the Invention

[0006] According to the present disclosure, the bonding quality of laminated substrates can be improved. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic plan view showing the configuration of a joining system according to an embodiment. [Diagram 2] FIG. 2 is a schematic side view showing the configuration of the joining system according to the embodiment. [Diagram 3] FIG. 3 is a schematic side view of the upper wafer and the lower wafer according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a processing gas supply unit according to this embodiment. [Diagram 5] FIG. 5 is a diagram illustrating another example of the configuration of the processing gas supply unit according to this embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing the configuration of the surface modification unit according to the embodiment. [Figure 7] FIG. 7 is a schematic plan view showing the configuration of the bonding device according to the embodiment. [Figure 8] FIG. 8 is a schematic side view showing the configuration of the joining device according to the embodiment. [Figure 9] FIG. 9 is a schematic side view showing the configurations of the upper chuck and the lower chuck of the joining device according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating a part of a processing procedure of the processing executed by the bonding system according to the embodiment. [Figure 11] FIG. 11 is a diagram for explaining details of the procedure of the surface modification process executed by the surface modification apparatus according to the embodiment. [Figure 12] FIG. 12 is a diagram for explaining details of the procedure of the surface modification process executed by the surface modification apparatus according to the embodiment. [Figure 13] FIG. 13 is a diagram for explaining details of the procedure of the surface modification process executed by the surface modification apparatus according to the embodiment. [Figure 14]FIG. 14 is a diagram for explaining details of the procedure of the surface modification process executed by the surface modification apparatus according to the embodiment. [Figure 15A] FIG. 15A is a diagram for explaining the transition of the surface state of the wafer in the reference example. [Figure 15B] FIG. 15B is a diagram for explaining the transition of the surface state of the wafer in the reference example. [Figure 15C] FIG. 15C is a diagram for explaining the transition of the surface state of the wafer in the reference example. [Figure 15D] FIG. 15D is a diagram for explaining the transition of the surface state of the wafer in the reference example. [Figure 15E] FIG. 15E is a diagram for explaining the transition of the surface state of the wafer in the reference example. [Figure 16A] FIG. 16A is a diagram for explaining the transition of the surface state of the wafer according to the embodiment. [Figure 16B] FIG. 16B is a diagram for explaining the transition of the surface state of the wafer according to the embodiment. [Figure 16C] FIG. 16C is a diagram for explaining the transition of the surface state of the wafer according to the embodiment. [Figure 16D] FIG. 16D is a diagram for explaining the transition of the surface state of the wafer according to the embodiment. [Figure 17] FIG. 17 is a diagram showing an example of a transition of pressure during pressure increase in the load lock chamber in the process gas supply process according to the embodiment. [Figure 18] FIG. 18 is a diagram showing an example of a transition of pressure during pressure increase in the load lock chamber in the process gas supply process according to the embodiment. [Figure 19] FIG. 19 is a schematic side view showing a configuration of a joint system according to a modified example of the embodiment. [Figure 20] FIG. 20 is a flowchart illustrating a part of a processing procedure executed by a joining system according to a modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the attached drawings, an embodiment of the bonding system and bonding method disclosed in the present application will be described in detail. Note that the present disclosure is not limited to the embodiment shown below. It should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from reality. Furthermore, there may be parts in which the dimensional relationship and ratio differ between the drawings.

[0009] Conventionally, a known 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).

[0010] On the other hand, if the surface of the substrate with the modified surface is exposed to the atmosphere before being hydrophilized, some of the dangling bonds of silicon atoms formed on the surface may be terminated by impurities in the atmosphere, which may reduce the bonding strength between the substrates and thus the bonding quality of the laminated substrate.

[0011] Therefore, there is a need for a technology that can overcome the above-mentioned problems and improve the bonding quality of laminated substrates.

[0012] <Configuration of the joining system> First, the configuration of a bonding system 1 according to an embodiment will be described with reference to Figs. 1 to 5. 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.

[0013] The bonding system 1 shown in FIGS. 1 and 2 forms a laminated substrate T by bonding a first substrate W1 and a second substrate W2 as shown in FIG.

[0014] The first substrate W1 is a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer on which a plurality of electronic circuits are formed. The second substrate W2 is a bare wafer on which no electronic circuits are formed. The first substrate W1 and the second substrate W2 have approximately the same diameter. The second substrate W2 may have electronic circuits formed thereon.

[0015] Hereinafter, the first substrate W1 will be referred to as the "upper wafer W1," the second substrate W2 will be referred to as the "lower wafer W2," and the overlapped substrate T will be referred to as the "overlapped wafer T." In other words, the upper wafer W1 is an example of the first substrate, the lower wafer W2 is an example of the second substrate, and the overlapped wafer T is an example of the overlapped substrate.

[0016] In the following, as shown in FIG. 3, the surface of the upper wafer W1 that is bonded to the lower wafer W2 will be referred to as the "bonding surface W1j," and the surface opposite the bonding surface W1j will be referred to as the "non-bonding surface W1n."

[0017] In addition, among the surfaces of the lower wafer W2, the surface on the side to be bonded to the upper wafer W1 is referred to as a “bonding surface W2j,” and the surface on the opposite side to the bonding surface W2j is referred to as a “non-bonding surface W2n.” The bonding surfaces W1j and W2j are examples of surfaces.

[0018] 1, the bonding 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 connected together.

[0019] The loading / unloading station 2 includes a mounting table 10 and a transfer area 20. The mounting table 10 includes a plurality of mounting plates 11. Cassettes C1, C2, and C3, each of which stores a plurality of substrates (e.g., 25 substrates) in a horizontal state, are placed on each of the mounting plates 11. For example, the cassette C1 is a cassette that stores an upper wafer W1, the cassette C2 is a cassette that stores a lower wafer W2, and the cassette C3 is a cassette that stores a laminated wafer T.

[0020] The transport area 20 is disposed adjacent to the mounting table 10 on the positive side in the X-axis direction. In the transport area 20, a transport path 21 extending in the Y-axis direction and a transport device 22 movable along the transport path 21 are provided.

[0021] The transfer device 22 is movable not only in the Y-axis direction but also in the X-axis direction and rotatable 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 a third processing block G3 of the processing station 3, which will be described later.

[0022] The number of cassettes C1 to C3 placed on the placement plate 11 is not limited to that shown in the figure. In addition to the cassettes C1, C2, and C3, a cassette for recovering defective substrates may be placed on the placement plate 11.

[0023] In the processing station 3, a plurality of processing blocks, for example three processing blocks G1, G2, G3 equipped with various devices are provided. For example, a first processing block G1 is provided on the rear side (positive Y-axis side in FIG. 1) of the processing station 3, and a second processing block G2 is provided on the front side (negative Y-axis side in FIG. 1) of the processing station 3. In addition, a third processing block G3 is provided on the loading / unloading station 2 side of the processing station 3 (negative X-axis side in FIG. 1).

[0024] A transfer area 60 is formed in an area surrounded by the first processing block G1 to the third processing block G3. The transfer area 60 is an example of an exterior. A transfer device 61 is disposed in the transfer area 60. The transfer device 61 has a transfer arm that is movable, for example, in the vertical direction, the horizontal direction, and around the vertical axis.

[0025] The transfer device 61 moves within the transfer region 60 to transfer the upper wafer W1, the lower wafer W2, and the overlapping 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 region 60.

[0026] Here, the upper wafer W1, the lower wafer W2, and the overlapped wafer T are transported by the transport device 61 in an air atmosphere at atmospheric pressure. Note that the atmospheric pressure does not need to be exactly the same as the atmospheric pressure at the location where the bonding system 1 is located, and may include a pressure range of, for example, ±10 kPa with respect to the atmospheric pressure.

[0027] The first processing block G1 is provided with a surface modification apparatus 30. The surface modification apparatus 30 has a surface modification unit 31 and a transfer unit 32. The transfer unit 32 has a load lock chamber 33 and a transfer chamber .

[0028] The surface modification unit 31 is disposed, for example, at a position closest to the load / unload station 2 in the first processing block G1, and is connected to the transfer unit 32 via a gate valve 35c on the positive X-axis direction side.

[0029] The transfer unit 32 transfers the upper wafer W1 or the lower wafer W2 between the outside (e.g., transfer area 60) and the surface modification unit 31 while being isolated from the atmospheric atmosphere present outside the surface modification apparatus 30. In the transfer unit 32, for example, a load lock chamber 33 is located on the positive side of the X-axis, and a transfer chamber 34 is located on the negative side of the X-axis.

[0030] The load lock chamber 33 and the transfer chamber 34 are connected via a gate valve 35b. The load lock chamber 33 and the transfer region 60 are connected via a gate valve 35a.

[0031] The load lock chamber 33 receives and delivers the upper wafer W1 and the lower wafer W2 between the transfer region 60 and the surface modification unit 31. In detail, as shown in Fig. 2, a plurality of transitions 33a1, 33a2 are provided inside the load lock chamber 33. The upper wafer W1 or the lower wafer W2 is placed on the plurality of transitions 33a1, 33a2.

[0032] For example, the transition 33a1 places the upper wafer W1 or the lower wafer W2 that is carried from the transfer region 60 to the surface modification unit 31. The transition 33a2 places the upper wafer W1 or the lower wafer W2 that is carried out from the surface modification unit 31 to the transfer region 60.

[0033] In the example of FIG. 2, the transitions 33a1 and 33a2 are arranged to be stacked in the vertical direction, but this is not limiting, and for example, they may be arranged to be adjacent to each other in a plan view.

[0034] A vacuum pump (not shown) is connected to the load lock chamber 33 via a suction pipe (not shown). When the gate valves 35a and 35b are closed and the vacuum pump is operated, the pressure inside the load lock chamber 33 is reduced to create a reduced pressure atmosphere.

[0035] In addition, a nitrogen gas supply unit 36 ​​and a process gas supply unit 37 are connected to the load lock chamber 33. The nitrogen gas supply unit 36 ​​has a nitrogen gas supply source 36a and a nitrogen gas supply pipe 36b, and supplies nitrogen gas into the inside of the load lock chamber 33.

[0036] The process gas supply unit 37 includes a process gas supply source 37 a and a process gas supply pipe 37 b , and supplies a process gas containing moisture into the load lock chamber 33 .

[0037] Fig. 4 is a diagram showing an example of the configuration of the processing gas supply unit 37 according to the embodiment. As shown in Fig. 4, the processing gas supply source 37a of the processing gas supply unit 37 includes a storage portion 37a1, a carrier gas supply source 37a2, and a carrier gas supply path 37a3. The storage portion 37a1 stores water. A processing gas supply pipe 37b is connected to the storage portion 37a1.

[0038] The process gas supply pipe 37b is provided at a position higher than the water surface in the storage section 37a1. The storage section 37a1 is, for example, a sealed container. The carrier gas supply path 37a3 connects the carrier gas supply source 37a2 and the storage section 37a1. The tip of the carrier gas supply path 37a3 (corresponding to the carrier gas discharge portion) is provided at a position lower than the water surface in the storage section 37a1.

[0039] The process gas supply source 37a configured as described above bubbles the water stored in the storage portion 37a1 with the carrier gas supplied from the carrier gas supply source 37a2 through the carrier gas supply path 37a3 to the storage portion 37a1.

[0040] As a result, a process gas containing moisture and components of the carrier gas is generated inside the storage portion 37a1. The process gas generated inside the storage portion 37a1 is supplied into the load lock chamber 33 via the process gas supply pipe 37b.

[0041] Fig. 5 is a diagram illustrating another example of the configuration of the processing gas supply unit 37 according to the embodiment. As illustrated in Fig. 5, the processing gas supply source 37a of the processing gas supply unit 37 may include a water supply source 37a4, a water supply passage 37a5, and a vaporizer 37a6.

[0042] Water supply source 37a4 supplies water. Water supply passage 37a5 connects water supply source 37a4 and vaporizer 37a6. Vaporizer 37a6 directly vaporizes the water supplied from water supply source 37a4 via water supply passage 37a5.

[0043] For example, the vaporizer 37a6 can vaporize water by applying heat to the water supplied from the water supply source 37a4 through the water supply passage 37a5. Any known technology may be used for the vaporizer 37a6. The vaporizer 37a6 is connected to the process gas supply pipe 37b.

[0044] The process gas supply source 37a configured as described above directly vaporizes water supplied from the water supply source 37a4 through the water supply path 37a5 using the vaporizer 37a6. This generates a process gas containing moisture but not carrier gas, and the generated process gas is supplied into the load lock chamber 33 through the process gas supply pipe 37b.

[0045] 1 and 2. The load-lock chamber 33 has its interior pressure increased to atmospheric pressure by nitrogen gas or the like supplied from a nitrogen gas supply unit 36, and when the gate valve 35a is opened, the interior communicates with the transfer region 60, which is under atmospheric pressure, and the interior atmosphere becomes atmospheric. In this way, the load-lock chamber 33 is configured so that the interior pressure can be adjusted from atmospheric pressure to a pressure lower than atmospheric pressure.

[0046] 1, a transfer device 34a is disposed in the transfer chamber 34. The transfer device 34a has a transfer arm that is movable, for example, in the vertical direction, the horizontal direction, and around a vertical axis.

[0047] The transfer device 34a receives, for example, the upper wafer W1 or the lower wafer W2 before modification placed on the transition 33a1 of the load lock chamber 33, and transfers it to the surface modification unit 31. In addition, the transfer device 34a transfers the upper wafer W1 or the lower wafer W2 modified in the surface modification unit 31 to the load lock chamber 33 and places it on the transition 33a2.

[0048] A vacuum pump (not shown) is connected to the transfer chamber 34 via a suction pipe (not shown). When the vacuum pump is operated, the pressure inside the transfer chamber 34 is reduced to create a reduced pressure atmosphere. The gate valve 35b is opened when the load lock chamber 33 is in a reduced pressure atmosphere. Similarly, the gate valve 35c is opened when the surface modification unit 31 is in a reduced pressure atmosphere.

[0049] Therefore, the transfer chamber 34 is constantly maintained at a reduced pressure by the vacuum pump. In this manner, the transfer device 34a of the transfer chamber 34 is disposed adjacent to the load lock chamber 33, and transfers the upper wafer W1 and the lower wafer W2 between the load lock chamber 33 and the surface modification unit 31 in a reduced pressure atmosphere.

[0050] The surface modification unit 31 modifies the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 one by one. A vacuum pump 131 (see FIG. 6) is connected to the surface modification unit 31 via a suction pipe 132 (see FIG. 6). When the vacuum pump 131 is operated, the interior of the surface modification unit 31 is depressurized to create a reduced pressure atmosphere. The surface modification unit 31 is also constantly in a reduced pressure atmosphere, similar to the transfer chamber 34.

[0051] Therefore, the surface modification unit 31 modifies the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 in a reduced pressure atmosphere. In detail, the surface modification unit 31 cuts the bonds of SiO2 on the bonding surfaces W1j, W2j of the upper wafer W1 and the lower wafer W2 to form single-bonded SiO, thereby modifying the bonding surfaces W1j, W2j so that they are easily hydrophilized thereafter.

[0052] In the surface modification unit 31, for example, oxygen gas, which is a processing gas, is excited to plasma and ionized in a reduced pressure atmosphere. The oxygen ions 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. The configuration of the surface modification unit 31 will be described in detail later.

[0053] The second processing block G2 is provided with a bonding device 41. The bonding device 41 bonds the upper wafer W1 and the lower wafer W2. The bonding device 41 will be described in detail later.

[0054] As shown in FIG. 2, in the third processing block G3, transition devices 50, 51 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T are provided in two stages in this order from the bottom.

[0055] 1, the bonding system 1 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 storage unit 6. The storage unit 6 stores programs for controlling 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 storage unit 6.

[0056] Such a program may be recorded on a computer-readable recording medium and installed from the recording medium into the storage 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 magnet optical disk (MO), and a memory card.

[0057] <Configuration of the surface modification unit> Next, the configuration of the surface modification unit 31 provided in the surface modification apparatus 30 will be described with reference to Fig. 6. Fig. 6 is a schematic cross-sectional view showing the configuration of the surface modification unit 31.

[0058] 6, the surface modification unit 31 has a processing container 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 surface of the processing container 70 on the transfer chamber 34 side, and a gate valve 35c is provided at the loading / unloading port 71.

[0059] 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 including, for example, a motor, are provided below the stage 80. The plurality of driving units 81 raise and lower the stage 80.

[0060] An exhaust ring 103 having a plurality of 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 uniformly exhausted from within the processing vessel 70.

[0061] A power feed rod 104 made of a conductor is connected to the underside of the stage 80. A high-frequency power supply 106 is connected to the power feed rod 104 via a matching device 105 formed of, for example, a blocking capacitor. During plasma processing, a given high-frequency voltage is applied to the stage 80 from the high-frequency power supply 106.

[0062] 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 gap therebetween. The gap between the upper surface of the stage 80 and the lower surface of the upper electrode 110 is adjusted by a driving unit 81.

[0063] The upper electrode 110 is grounded and connected to a ground potential. Since the upper electrode 110 is grounded in this manner, damage to the lower surface of the upper electrode 110 during plasma processing can be suppressed.

[0064] In this manner, a high frequency voltage is applied from the high frequency power supply 106 to the stage 80 serving as the lower electrode, whereby plasma is generated within the processing vessel 70 .

[0065] In the embodiment, the stage 80, the power feed rod 104, the matching box 105, the high frequency power supply 106, and the upper electrode 110 are an example of a plasma generating mechanism that generates plasma of the processing gas in the processing vessel 70. The high frequency power supply 106 is controlled by the control unit 5 of the control device 4 described above.

[0066] 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 therein. The gas supply pipe 121 is provided with a supply device group 123 including valves and flow rate regulators that control the flow of the processing gas and the static elimination gas.

[0067] The processing gas and the 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 processing gas. For example, an inert gas such as nitrogen gas or argon gas is used as the static elimination gas.

[0068] A baffle plate 124 for promoting uniform diffusion of the processing gas and the static elimination gas is provided inside the hollow portion 120. A large number of small holes are provided in the baffle plate 124. A large number of gas outlets 125 for ejecting the processing gas and the static elimination gas from the hollow portion 120 into the processing vessel 70 are formed on the lower surface of the upper electrode 110.

[0069] An intake port 130 is formed in the processing vessel 70. The intake port 130 is connected to a suction pipe 132 that communicates with a vacuum pump 131 that reduces the pressure inside the processing vessel 70 to a given vacuum level.

[0070] 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 those of 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 a placement portion 91 of the stage cover 90.

[0071] <Configuration of the joining device> Next, the configuration of the joining device 41 will be described with reference to Fig. 7 to Fig. 9. Fig. 7 is a schematic plan view showing the configuration of the joining device 41 according to the embodiment, and Fig. 8 is a schematic side view showing the configuration of the joining device 41 according to the embodiment.

[0072] 7, the bonding apparatus 41 has a processing container 190 whose interior can be sealed. A loading / unloading port 191 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T is formed on a side surface of the processing container 190 facing the transfer region 60, and an opening / closing shutter 192 is provided at the loading / unloading port 191.

[0073] The inside 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 a side surface of the processing vessel 190 in the transfer region T1. In addition, a loading / unloading port 194 for the upper wafer W1, the lower wafer W2, and the overlapped wafer T is also formed in the inner wall 193.

[0074] The inside of the processing vessel 190 is maintained at a given constant humidity by a humidity maintaining mechanism (not shown), so that the bonding device 41 can perform the bonding process of the upper wafer W1 and the lower wafer W2 in a stable environment.

[0075] A transition 200 is provided on the Y-axis negative direction 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.

[0076] 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.

[0077] A position adjustment mechanism 210 that adjusts the horizontal orientation of the upper wafer W1 and the lower wafer W2 is provided on the Y-axis positive side of the transfer region T1. The 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).

[0078] Thereby, 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. Further, in the transfer region T1, an inversion mechanism 220 that inverts the front and back surfaces of the upper wafer W1 is provided.

[0079] 8, an upper chuck 230 and a lower chuck 231 are provided in the processing region T2. ​​The upper chuck 230 adsorbs and holds the upper wafer W1 from above. The lower chuck 231 is provided below the upper chuck 230 and adsorbs and 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.

[0080] 8, 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.

[0081] 7 and 8, 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 capable of moving the lower chuck 231 in the vertical direction and to be rotatable around a vertical axis.

[0082] 7, 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.

[0083] 7 and 8, the first lower chuck moving part 310 is provided on the lower surface side of the first lower chuck moving part 310 and attached to a pair of rails 315 extending in the horizontal direction (Y-axis direction). The first lower chuck moving part 310 is configured to be movable along the rails 315.

[0084] The pair of rails 315 is provided on a 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 lower surface side of the second lower chuck moving part 316 and extend in the horizontal direction (X-axis direction).

[0085] The second lower chuck moving part 316 is configured to be movable along the rails 317, that is, to move the lower chuck 231 in the horizontal direction (X-axis direction). The pair of rails 317 is provided on a mounting table 318 provided on the bottom surface of the processing vessel 190.

[0086] 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. 9. Fig. 9 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.

[0087] 9, the upper chuck 230 is partitioned into a plurality of, for example, three, regions 230a, 230b, and 230c. These regions 230a, 230b, and 230c are provided in this order from the center toward the peripheral portion (outer periphery) of the upper chuck 230. The region 230a has a circular shape in a plan view, and the regions 230b and 230c have annular shapes in a plan view.

[0088] As shown in Fig. 9, suction pipes 240a, 240b, 240c for suction-holding the upper wafer W1 are provided independently in the respective regions 230a, 230b, 230c. Different vacuum pumps 241a, 241b, 241c are connected to the respective suction pipes 240a, 240b, 240c. In this manner, 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, 230c.

[0089] 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 W1a of the upper wafer W1 attracted and held by the upper chuck 230. A pressing pin 253 of a substrate pressing mechanism 250 is inserted into the through hole 243.

[0090] The substrate pressing mechanism 250 is provided on the upper surface of the upper chuck 230, and presses the center portion W1a of the upper wafer W1 with a pressing pin 253. The pressing pin 253 is provided so as to be linearly movable along a vertical axis by a cylinder portion 251 and an actuator portion 252, and presses the opposing substrate (in this embodiment, the upper wafer W1) with its tip.

[0091] Specifically, the pressing pin 253 serves as a starter that first brings the center W1a of the upper wafer W1 and the center W2a of the lower wafer W2 into contact with each other when bonding the upper wafer W1 and the lower wafer W2 together, as described below.

[0092] The lower chuck 231 is substantially disk-shaped and is partitioned into a plurality of regions, for example, two regions 231a and 231b. These regions 231a and 231b are provided in this order from the center toward the periphery of the lower chuck 231. The region 231a has a circular shape in a plan view, and the region 231b has an annular shape in a plan view.

[0093] 9, suction pipes 260a, 260b for suction-holding the lower wafer W2 are provided independently in the respective regions 231a, 231b. Different vacuum pumps 261a, 261b are connected to the respective suction pipes 260a, 260b. In this manner, 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.

[0094] On the periphery of the lower chuck 231, stopper members 263 for preventing the upper wafer W1, the lower wafer W2 and the overlapped wafer T from jumping out or slipping off the lower chuck 231 are provided at a plurality of positions, for example, five positions.

[0095] <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. 10 to Fig. 18. Note that the various processes described below are executed based on the control by the control unit 5 of the control device 4.

[0096] 10 is a flowchart showing a part of a processing procedure executed by the bonding system 1 according to the embodiment. First, the cassette C1 containing a plurality of upper wafers W1, the cassette C2 containing a plurality of lower wafers W2, and the empty cassette C3 are placed on a given placement plate 11 of the carry-in / out station 2.

[0097] Thereafter, 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.

[0098] Next, the upper wafer W1 is transferred by the transfer device 61 to the surface modification device 30 in the first processing block G1, where the surface modification processing of the upper wafer W1 is performed (step S101). The details of the surface modification processing in the surface modification device 30 will be described with reference to FIGS. 11 to 14.

[0099] 11 to 14 are diagrams for explaining details of the procedure of the surface modification process performed by the surface modification apparatus 30 according to the embodiment. In the following explanation, the upper wafer W1 and the lower wafer W2 may be collectively referred to as "wafer W", and the bonding surface W1j and the bonding surface W2j may be collectively referred to as "bonding surface Wj".

[0100] First, as shown in Fig. 11, the control unit 5 (see Fig. 1) opens the gate valve 35a in the load lock chamber 33 whose pressure has been increased to atmospheric pressure, and loads the wafer W from the transfer region 60 (see Fig. 1) into the load lock chamber 33 via the gate valve 35a (step S01). The wafer W loaded into the load lock chamber 33 is placed on, for example, the transition 33a1.

[0101] Next, the control unit 5 closes the gate valve 35a and controls a vacuum pump (not shown) connected to the load lock chamber 33 to reduce the pressure inside the load lock chamber 33 to a given pressure (for example, about several tens of Pa) (step S02). Details of this depressurization step will be described later.

[0102] Next, as shown in FIG. 12, the control unit 5 (see FIG. 1) opens the gate valves 35b and 35c, and controls the transfer device 34a to transfer the wafer W placed on the transition 33a1 into the surface modification unit 31 (step S03).

[0103] Next, the control unit 5 closes the gate valves 35b and 35c, and modifies the bonding surface Wj of the wafer W with plasma in the surface modification unit 31 (step S04). As a result, dangling bonds of silicon atoms are formed on the outermost surface of the bonding surface Wj.

[0104] 13, the control unit 5 (see FIG. 1) opens the gate valves 35b and 35c, and controls the transfer device 34a to transfer the wafer W whose bonding surface Wj has been modified into the load lock chamber 33 (step S05). The wafer W transferred to the load lock chamber 33 is placed on, for example, the transition 33a2.

[0105] Next, the control unit 5 closes the gate valves 35b and 35c, and controls the processing gas supply unit 37 (see FIG. 2) to supply the processing gas containing moisture into the load-lock chamber 33 (step S06). The effect of step S06 will be described later.

[0106] Next, as shown in FIG. 14, the control unit 5 (see FIG. 1) controls the nitrogen gas supply unit 36 ​​(see FIG. 2) and the like to increase the pressure inside the load lock chamber 33 to atmospheric pressure (step S07).

[0107] Next, the control unit 5 opens the gate valve 35a in the load lock chamber 33, which has been pressurized to atmospheric pressure, and transfers the wafer W from the load lock chamber 33 to the transfer area 60 (see FIG. 1) via the gate valve 35a (step S08), thereby completing the series of surface modification processes.

[0108] When the wafer W whose bonding surface Wj has not yet been modified is carried into the load lock chamber 33, a wafer W whose bonding surface Wj has already been modified in a previous process may be placed on the transition 33a2. In this case, the transfer device 61 may place the wafer W before modification on the transition 33a1, and then receive the modified wafer W on the transition 33a2 and carry it out of the load lock chamber 33.

[0109] Next, the effect of the process of bringing a moisture-containing process gas into contact with the modified wafer W inside the load lock chamber 33 in the series of surface modification processes described above will be described with reference to FIGS. 15A to 16D.

[0110] 15A to 15E are diagrams for explaining the transition of the surface state of the wafer W in a reference example. This reference example is an example in which the process of supplying a processing gas containing moisture to the inside of the load lock chamber 33 is not performed.

[0111] As shown in FIG. 15A, on the bonding surface Wj of the wafer W before the surface modification process, silicon atoms on the outermost surface are terminated with various atoms and molecules.

[0112] Therefore, by modifying the bonding surface Wj of the wafer W with plasma in the surface modification unit 31 (step S04 described above), dangling bonds of silicon atoms are formed on the outermost surface of the bonding surface Wj, as shown in Fig. 15B. Then, while the wafer W stays inside the surface modification unit 31 and the transfer unit 32 under reduced pressure, the dangling bonds are maintained in almost the same state.

[0113] However, when the silicon wafer is transported from the load lock chamber 33 to the outside, such as the transfer region 60, a large amount of impurities A (hydrogen molecules, organic matter, etc.) are present in the atmospheric air, and as shown in FIG. 15C, at least a portion of the dangling bonds of the silicon atoms are terminated by these impurities A.

[0114] In this reference example, after the surface modification process in the surface modification apparatus 30, the bonding surface Wj is hydrophilized by a surface hydrophilization apparatus (not shown). As a result, as shown in Fig. 15D, OH groups (silanol groups) are attached to the dangling bonds of the remaining silicon atoms on the bonding surface Wj of the modified wafer W, and the bonding surface Wj is hydrophilized.

[0115] Finally, as shown in Fig. 15E, van der Waals forces (intermolecular forces) are generated between the upper wafer W1, whose bonding surface W1j has been hydrophilized, and the lower wafer W2, whose bonding surface W2j has been hydrophilized, in the bonding device 41 (see Fig. 1), and the bonding surfaces W1j and W2j are bonded together. Furthermore, OH groups between the bonding surfaces W1j and W2j form hydrogen bonds, and the bonding surfaces W1j and W2j are firmly bonded together.

[0116] However, in the reference example, since the dangling bonds of silicon atoms are terminated by the impurity A in no small amount before the surface hydrophilization treatment, the hydrogen bonds between the OH groups at the interface are reduced, and the bonding strength between the upper wafer W1 and the lower wafer W2 is reduced. This may result in a deterioration in the bonding quality of the overlapped wafer T.

[0117] 16A to 16D are diagrams for explaining the transition of the surface state of the wafer W according to the embodiment. As shown in Fig. 16A, as in the above-described reference example, on the bonding surface Wj of the wafer W before the surface modification process, silicon atoms on the outermost surface are terminated with various atoms and molecules.

[0118] Therefore, by modifying the bonding surface Wj of the wafer W with plasma in the surface modification unit 31 (step S04 described above), dangling bonds of silicon atoms are formed on the outermost surface of the bonding surface Wj, as shown in Fig. 16B. Then, while the wafer W stays inside the surface modification unit 31 and the transfer unit 32 under reduced pressure, the dangling bonds are maintained in almost the same state.

[0119] In the embodiment, the control unit 5 (see FIG. 1) brings a process gas containing moisture into contact with the wafer W inside the load lock chamber 33 under reduced pressure. As a result, as shown in FIG. 16C, OH groups are attached to the dangling bonds of many silicon atoms, and the dangling bonds are terminated.

[0120] Once the OH groups have terminated the dangling bonds of the silicon atoms, they are unlikely to leave even if the surface modification apparatus 30 is subsequently exposed to the air atmosphere outside the apparatus.

[0121] Therefore, when the upper wafer W1 and the lower wafer W2 are bonded in the bonding apparatus 41 (see FIG. 1), many OH groups between the bonding surfaces W1j and W2j are hydrogen-bonded as shown in FIG. 16D, so that the bonding surfaces W1j and W2j are bonded more firmly to each other. Therefore, according to the embodiment, the bonding quality of the overlapped wafer T can be improved.

[0122] In addition, in the embodiment, a surface hydrophilization device that was used in the conventional technology to perform hydrophilization treatment on the bonding surface Wj is not required, so that the bonding process of the overlapped wafers T can be simplified and the manufacturing cost of the bonding system 1 can be reduced.

[0123] In the embodiment, the wafer W after the surface modification process may be brought into contact with the moisture-containing process gas inside the load lock chamber 33, rather than inside the surface modification unit 31 or the transfer chamber 34. In other words, in the embodiment, the process gas supply unit 37 that supplies the moisture-containing process gas may be connected to the load lock chamber 33.

[0124] If a processing gas is supplied to the transfer chamber 34, the molecular density inside the transfer chamber 34 is too low because the transfer chamber 34 is maintained at a high vacuum (for example, about 10 Pa), so that water molecules have difficulty in reaching the dangling bonds, and it is relatively difficult to efficiently terminate them with OH groups. The same is true for the surface modification unit 31.

[0125] On the other hand, since the load lock chamber 33 operates in a wide pressure range from high vacuum to atmospheric pressure, the dangling bonds of silicon atoms can be efficiently terminated with OH groups by supplying a process gas containing moisture in an appropriate pressure range. Therefore, according to the embodiment, the bonding quality of the laminated wafer T can be further improved.

[0126] 17 is a diagram showing an example of pressure transition during pressure increase in the load lock chamber 33 in the process gas supply process according to the embodiment. As shown in Fig. 17, in the embodiment, after the wafer W after the surface modification process is transferred into the load lock chamber 33 and the gate valve 35b (see Fig. 1) is closed, the pressure inside the load lock chamber 33 is increased from time T10.

[0127] In this embodiment, the control unit 5 (see FIG. 1) increases the pressure inside the load lock chamber 33 only with nitrogen gas from the nitrogen gas supply unit 36 ​​(see FIG. 2) from pressure P0 at time T10 to a given pressure P1 (for example, about 1000 Pa) at time T11. Pressure P1 is an example of a first pressure.

[0128] Then, from time T11 when the pressure reaches the given pressure P1, the control unit 5 increases the pressure inside the load lock chamber 33 using the processing gas from the processing gas supply unit 37. In this case, the pressure inside the load lock chamber 33 may be increased using nitrogen gas from the nitrogen gas supply unit 36 ​​as well, or the pressure inside the load lock chamber 33 may be increased only by the processing gas from the processing gas supply unit 37.

[0129] In this manner, by supplying the processing gas under a pressure higher than the given pressure P1, the dangling bonds of the silicon atoms can be efficiently terminated with OH groups. Therefore, according to the embodiment, the bonding quality of the overlapped wafer T can be further improved.

[0130] In the embodiment, the controller 5 increases the pressure inside the load lock chamber 33 by using the process gas from the process gas supply unit 37 until time T12 when the pressure reaches a given pressure P2 (for example, about 2000 Pa). The pressure P2 is an example of a second pressure.

[0131] Then, from time T12 when the pressure reaches the given pressure P2, the control unit 5 again increases the pressure inside the load lock chamber 33 to atmospheric pressure using only the nitrogen gas from the nitrogen gas supply unit .

[0132] This makes it possible to suppress condensation that occurs when a processing gas containing moisture is supplied under reduced pressure closer to atmospheric pressure. That is, it is possible to suppress the need for a long time for evacuation due to condensation remaining inside the load lock chamber 33 when the next wafer W is loaded into the surface modification apparatus 30.

[0133] Therefore, according to the embodiment, the throughput of the surface modification apparatus 30 can be improved.

[0134] 18 is a diagram showing an example of pressure transition during decompression inside the load lock chamber 33 in the process gas supply process according to the embodiment. As shown in Fig. 18, when decompressing the inside of the load lock chamber 33 into which the unmodified wafer W has been loaded, the control unit 5 (see Fig. 1) reduces the capacity of the vacuum pump to reduce the pressure from atmospheric pressure to a given pressure P3 (e.g., about 2000 Pa) without fully opening the vacuum pump.

[0135] After the pressure reaches a given pressure P3, the control unit 5 operates the vacuum pump to full capacity to reduce the pressure inside the load lock chamber 33.

[0136] This makes it possible to prevent moisture remaining inside the load lock chamber 33, which is caused by the processing gas supplied to the wafer W that was previously modified, from solidifying into water droplets due to a sudden reduction in pressure from atmospheric pressure.

[0137] That is, it is possible to prevent a long time from being required for evacuation when the next wafer W is carried into the surface modification apparatus 30. Therefore, according to the embodiment, the throughput of the surface modification apparatus 30 can be improved.

[0138] In addition, in the embodiment, the surface modification apparatus 30 has a load lock chamber 33 in which the upper wafer W1 and the lower wafer W2 are transferred between the transport area 60 and the surface modification unit 31, and in which the atmosphere in the chamber can be switched between atmospheric atmosphere and reduced pressure atmosphere.

[0139] This makes it possible to shorten the processing time of the upper wafer W1 and the lower wafer W2 in the bonding system 1. That is, if the internal pressure of the load lock chamber 33 is switched when the upper wafer W1 and the lower wafer W2 are carried in and out of the surface modification unit 31, the surface modification unit 31 can perform the modification process while maintaining a reduced pressure atmosphere.

[0140] Therefore, in the surface modification unit 31, since the process of switching from the air atmosphere to a reduced pressure atmosphere is not required, the time required for the modification process of the upper wafer W1 and the lower wafer W2 can be shortened.

[0141] In addition, the load lock chamber 33 is preferably set so that its internal volume is smaller than the internal volumes of the surface modification unit 31 and the transfer chamber 34. This makes it possible to shorten the time required to switch the internal pressure of the load lock chamber 33 compared to the time required to switch the internal pressure of the surface modification unit 31.

[0142] Furthermore, it is preferable that the transfer device 34a that transfers the wafer W inside the transfer unit 32 is disposed not in the load lock chamber 33 but in the transfer chamber 34 adjacent to the load lock chamber 33. This allows the load lock chamber 33 to be made smaller than when the transfer device 34a is disposed therein, and as a result, the time required to switch the pressure inside the chamber can be further shortened.

[0143] In the embodiment described above, the example in which the processing gas containing moisture is brought into contact with the modified wafer W in the load lock chamber 33 has been shown, but the present disclosure is not limited to this example.

[0144] For example, a processing gas containing moisture may be brought into contact with the modified wafer W in the transfer chamber 34, or the modified wafer W may be brought into contact with the processing gas containing moisture when passing through the gate valve 35c or the gate valve 35b.

[0145] In addition, a separate processing chamber that is isolated from the atmospheric air and has an internal pressure of atmospheric pressure may be provided between the transfer region 60 and the load lock chamber 33, and a processing gas containing moisture may be brought into contact with the modified wafer W transferred from the load lock chamber 33 to this processing chamber.

[0146] With these measures, the bonding quality of the overlapped wafer T can be improved by contacting the modified wafer W with a processing gas containing moisture before the modified wafer W comes into contact with the air atmosphere outside the surface modification apparatus 30.

[0147] Returning to the explanation of Fig. 10, the upper wafer W1 that has been subjected to the surface modification treatment (step S101) described above 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 carried into the bonding device 41 is transferred to the position adjustment mechanism 210 via the transition 200. Then, the horizontal orientation of the upper wafer W1 is adjusted by the position adjustment mechanism 210 (step S102).

[0148] Thereafter, 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 S103). That is, the bonding surface W1j of the upper wafer W1 faces downward.

[0149] Thereafter, the inversion mechanism 220 rotates and moves to a position below the upper chuck 230. Then, the upper wafer W1 is delivered from the inversion mechanism 220 to the upper chuck 230. The upper wafer W1 has its non-bonding surface W1n attracted and held by the upper chuck 230 (step S104).

[0150] While the upper wafer W1 is being subjected to the processes in the above-mentioned steps S101 to S104, the lower wafer W2 is being processed. First, the transfer device 22 takes out the lower wafer W2 from the cassette C2 and transfers it to the transition device 50 of the processing station 3.

[0151] Next, the lower wafer W2 is transferred to the surface modification device 30 by the transfer device 61, and the bonding surface W2j of the lower wafer W2 is modified by plasma of the processing gas (step S105). Note that since step S105 is the same process as step S101 described above, detailed description thereof will be omitted.

[0152] Thereafter, the lower wafer W2 is transferred to the bonding apparatus 41 by the transfer device 61. The lower wafer W2 carried into the bonding apparatus 41 is transferred to the position adjustment mechanism 210 via the transition 200. Then, the horizontal orientation of the lower wafer W2 is adjusted by the position adjustment mechanism 210 (step S106).

[0153] Thereafter, the lower wafer W2 is transferred to the lower chuck 231 and adsorbed and held by the lower chuck 231 (step S107). The lower wafer W2 has its non-bonding surface W2n adsorbed and held by the lower chuck 231 with the notch portion facing a predetermined direction.

[0154] 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 S108).

[0155] 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. As a result, 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 are adjusted (step S109).

[0156] 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.

[0157] Next, the pressing pin 253 of the substrate pressing mechanism 250 is lowered to press down the center W1a of the upper wafer W1, thereby pressing the center W1a of the upper wafer W1 and the center W2a of the lower wafer W2 with a given force (step S110).

[0158] This starts bonding between the center W1a of the pressed upper wafer W1 and the center W2a 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 are modified in steps S101 and S105, respectively, van der Waals force (intermolecular force) is generated between the bonding surfaces W1j and W2j, and the bonding surfaces W1j and W2j are bonded to each other.

[0159] Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are 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.

[0160] Thereafter, the bonding area between the upper wafer W1 and the lower wafer W2 expands from the center to the outer periphery of the upper wafer W1 and the lower wafer W2. Thereafter, while the center W1a of the upper wafer W1 and the center W2a of the lower wafer W2 are pressed by the pressing pin 253, the operation of the vacuum pump 241b is stopped to stop the vacuum suction of the upper wafer W1 from the suction pipe 240b in the region 230b.

[0161] Then, the upper wafer W1 held in the region 230b falls onto the lower wafer W2. After that, the operation of the vacuum pump 241c is stopped to stop the evacuation of the upper wafer W1 from the suction pipe 240c in the region 230c.

[0162] In this manner, the vacuum pumping of the upper wafer W1 is stopped stepwise from the center W1a of the upper wafer W1 toward the outer periphery, and the upper wafer W1 drops stepwise onto and comes into contact with the lower wafer W2. Then, the bonding between the bonding surfaces W1j and W2j by the van der Waals forces and hydrogen bonds gradually spreads from the center W1a and W2a toward the outer periphery.

[0163] In this manner, the entire bonding surface W1j of the upper wafer W1 and the entire bonding surface W2j of the lower wafer W2 are brought into contact with each other, and the upper wafer W1 and the lower wafer W2 are bonded together (step S111).

[0164] Thereafter, the pressing pin 253 is raised to the upper chuck 230. Moreover, the suction of the lower wafer W2 from the suction pipes 260a and 260b in the lower chuck 231 is stopped, and the suction and holding of the lower wafer W2 by the lower chuck 231 is released. This ends the bonding process in the bonding system 1.

[0165] <Modification> Next, a modified example of the embodiment will be described with reference to Fig. 19 and Fig. 20. Fig. 19 is a schematic side view showing the configuration of a joint system 1 according to a modified example of the embodiment, and corresponds to Fig. 2 of the embodiment.

[0166] 19, the bonding system 1 according to the modified example is different from the above embodiment in that it is provided with a surface hydrophilization device 38. The surface hydrophilization device 38 is located, for example, on the positive Z-axis side of the surface modification device 30 in the first processing block G1.

[0167] In the surface hydrophilization device 38, pure water is supplied onto the upper wafer W1 or the lower wafer W2 while rotating the upper wafer W1 or the lower wafer W2 held by, for example, a spin chuck. 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.

[0168] 20 is a flowchart showing a part of a processing procedure executed by the bonding system 1 according to the modified example of the embodiment. Note that the various processes shown below are executed based on the control by the control unit 5 of the control device 4.

[0169] First, the cassette C1 accommodating a plurality of upper wafers W1, the cassette C2 accommodating a plurality of lower wafers W2, and the empty cassette C3 are placed on a given placement plate 11 of the carry-in / out station 2.

[0170] Thereafter, 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.

[0171] Next, the upper wafer W1 is transferred by the transfer device 61 to the surface modification device 30 in the first processing block G1, where the surface modification processing of the upper wafer W1 is performed (step S201). The processing of step S201 is similar to the processing of step S101 described above, and therefore a detailed description thereof will be omitted.

[0172] Next, the upper wafer W1 is transferred to the surface hydrophilization device 38 in the first processing block G1 by the transfer device 61. In the surface hydrophilization device 38, pure water is supplied onto the upper wafer W1 while the upper wafer W1 held by a spin chuck is being rotated.

[0173] Then, the supplied pure water is diffused on the bonding surface W1j of the upper wafer W1. As a result, in the surface hydrophilization device 38, OH groups (silanol groups) are attached to the dangling bonds of the remaining silicon atoms on the modified bonding surface W1j of the upper wafer W1, and the bonding surface W1j is hydrophilized (step S202). In addition, the bonding surface W1j of the upper wafer W1 is cleaned by the pure water.

[0174] Next, the upper wafer W1 is transferred to the bonding device 41 in the second processing block G2 by the transfer device 61. The upper wafer W1 carried into the bonding device 41 is transferred to the position adjustment mechanism 210 via the transition 200. Then, the horizontal orientation of the upper wafer W1 is adjusted by the position adjustment mechanism 210 (step S203).

[0175] Thereafter, 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 S204). That is, the bonding surface W1j of the upper wafer W1 faces downward.

[0176] Thereafter, the inversion mechanism 220 rotates and moves to a position below the upper chuck 230. Then, the upper wafer W1 is delivered from the inversion mechanism 220 to the upper chuck 230. The upper wafer W1 has its non-bonding surface W1n attracted and held by the upper chuck 230 (step S205).

[0177] While the upper wafer W1 is being subjected to the processes in the above-mentioned steps S201 to S205, the lower wafer W2 is being processed. First, the transfer device 22 takes out the lower wafer W2 from the cassette C2 and transfers it to the transition device 50 of the processing station 3.

[0178] Next, the lower wafer W2 is transferred to the surface modification device 30 by the transfer device 61, and the bonding surface W2j of the lower wafer W2 is modified by plasma of the processing gas (step S206). Note that since step S206 is the same process as step S101 described above, detailed description thereof will be omitted.

[0179] Next, the lower wafer W2 is transferred to the surface hydrophilization device 38 in the first processing block G1 by the transfer device 61. In the surface hydrophilization device 38, pure water is supplied onto the lower wafer W2 while the lower wafer W2 held by a spin chuck is being rotated.

[0180] Then, the supplied pure water is diffused on the bonding surface W2j of the lower wafer W2. As a result, in the surface hydrophilization device 38, OH groups (silanol groups) are attached to the dangling bonds of the remaining silicon atoms on the modified bonding surface W2j of the lower wafer W2, and the bonding surface W2j is hydrophilized (step S207). In addition, the bonding surface W2j of the lower wafer W2 is cleaned by the pure water.

[0181] Thereafter, the lower wafer W2 is transferred to the bonding apparatus 41 by the transfer device 61. The lower wafer W2 carried into the bonding apparatus 41 is transferred to the position adjustment mechanism 210 via the transition 200. Then, the horizontal orientation of the lower wafer W2 is adjusted by the position adjustment mechanism 210 (step S208).

[0182] Thereafter, the lower wafer W2 is transferred to the lower chuck 231 and adsorbed and held by the lower chuck 231 (step S209). The lower wafer W2 has its non-bonding surface W2n adsorbed and held by the lower chuck 231 with the notch portion facing a predetermined direction.

[0183] 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 S210).

[0184] 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. As a result, 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 are adjusted (step S211).

[0185] Next, the pressing pin 253 of the substrate pressing mechanism 250 is lowered to press down the center W1a of the upper wafer W1, thereby pressing the center W1a of the upper wafer W1 and the center W2a of the lower wafer W2 with a given force (step S212).

[0186] This starts bonding between the center W1a of the pressed upper wafer W1 and center W2a of the lower wafer W2. Thus, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 come into full contact with each other, and the upper wafer W1 and the lower wafer W2 are bonded together (step S213). The processes in steps S210 to S213 are similar to the processes in steps S108 to S111 described above, and therefore detailed description thereof will be omitted.

[0187] Thereafter, the pressing pin 253 is raised to the upper chuck 230. Moreover, the suction of the lower wafer W2 from the suction pipes 260a and 260b in the lower chuck 231 is stopped, and the suction and holding of the lower wafer W2 by the lower chuck 231 is released. This ends the bonding process in the bonding system 1 according to the modified example.

[0188] Here, in the modified example, as described above, a wafer W in which many of the dangling bonds of silicon atoms have been terminated by a moisture-containing processing gas in the surface modification apparatus 30 is subjected to a hydrophilization process of the bonding surface Wj in a separate surface hydrophilization apparatus 38.

[0189] This makes it possible to terminate dangling bonds of silicon atoms that were not terminated by the surface modification device 30. Furthermore, in the modified example, the bonding process of the upper wafer W1 and the lower wafer W2 can be performed while a water film is formed between the bonding surfaces W1j and W2j, so that the influence of slight unevenness present on the bonding surfaces W1j and W2j can be reduced by this water film.

[0190] Therefore, according to the modified example, the bonding quality of the overlapped wafer T can be further improved.

[0191] The bonding system 1 according to the embodiment includes a surface modification device 30 and a bonding device 41. The surface modification device 30 modifies the surfaces (bonding surfaces W1j, W2j) of the first substrate (upper wafer W1) and the second substrate (lower wafer W2). The bonding device 41 bonds the first substrate (upper wafer W1) and the second substrate (lower wafer W2) modified by the surface modification device 30 by intermolecular forces. The surface modification device 30 also includes a surface modification unit 31, a transfer unit 32, and a processing gas supply unit 37. The surface modification unit 31 modifies the surfaces (bonding surfaces W1j, W2j) of the first substrate (upper wafer W1) and the second substrate (lower wafer W2) one by one. The transfer unit 32 transfers the first substrate (upper wafer W1) or the second substrate (lower wafer W2) between the outside (transfer area 60) and the surface modification unit 31 in a state isolated from the outside atmosphere. The processing gas supply unit 37 supplies a processing gas containing moisture to the inside of the transfer unit 32. This makes it possible to improve the bonding quality of the laminated wafers T.

[0192] Moreover, in the bonding system 1 according to the embodiment, the transfer unit 32 has a load lock chamber 33 configured so that the pressure inside can be adjusted from atmospheric pressure to a pressure lower than atmospheric pressure. Moreover, the process gas supply unit 37 supplies a process gas to the load lock chamber 33. This can further improve the bonding quality of the laminated wafers T.

[0193] The bonding system 1 according to the embodiment further includes a control unit 5 that controls each unit. When the first substrate (upper wafer W1) and the second substrate (lower wafer W2) whose surfaces (bonding surfaces W1j, W2j) have been modified by the surface modification unit 31 are carried into the load lock chamber 33, the control unit 5 supplies a processing gas to the load lock chamber 33 via the processing gas supply unit 37.

[0194] In the bonding system 1 according to the embodiment, the surface modification device 30 further includes a nitrogen gas supply unit 36 ​​that supplies nitrogen gas to the inside of the load lock chamber 33. The control unit 5 executes a first process and a second process. In the first process, after the first substrate (upper wafer W1) and the second substrate (lower wafer W2) whose surfaces (bonding surfaces W1j, W2j) have been modified by the surface modification unit 31 are carried into the load lock chamber 33, the load lock chamber 33 is pressurized to a given first pressure (pressure P1) using only the nitrogen gas from the nitrogen gas supply unit 36. In the second process, the load lock chamber 33 is pressurized from the first pressure (pressure P1) using a process gas. This can further improve the bonding quality of the overlapped wafers T.

[0195] Moreover, in the bonding system 1 according to the embodiment, the control unit 5 increases the pressure in the load lock chamber 33 to a given second pressure (pressure P2) using a processing gas in the second process. Moreover, the control unit 5 further executes a third process in which the pressure in the load lock chamber 33 is increased from the second pressure (pressure P2) to atmospheric pressure using only nitrogen gas from the nitrogen gas supply unit 36. This can improve the throughput in the surface modification apparatus 30.

[0196] Moreover, the bonding system 1 according to the embodiment further includes a surface hydrophilization device 38 that hydrophilizes the surfaces of the first substrate (upper wafer W1) and the second substrate (lower wafer W2) modified by the surface modification device 30. This can further improve the bonding quality of the laminated wafer T.

[0197] The bonding method according to the embodiment includes a surface modification step (steps S101 and S105) and a bonding step (step S111). The surface modification step (steps S101 and S105) modifies the surfaces (bonding surfaces W1j and W2j) of the first substrate (upper wafer W1) and the second substrate (lower wafer W2). The bonding step (step S111) bonds the first substrate (upper wafer W1) and the second substrate (lower wafer W2) modified in the surface modification step (steps S101 and S105) by intermolecular forces. In addition, in the surface modification process (steps S101, S105), a processing gas containing moisture is brought into contact with the surface (bonding surface W1j, W2j) of the first substrate (upper wafer W1) or the second substrate (lower wafer W2) whose surface (bonding surface W1j, W2j) has been modified, before the first substrate (upper wafer W1) or the second substrate (lower wafer W2) comes into contact with the atmospheric air.

[0198] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0199] The disclosed embodiments should be considered to be illustrative and not restrictive in all respects. 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. [Explanation of symbols]

[0200] 1 Joining System 5. Control section 30 Surface modification equipment 31 Surface Modification Unit 32 Transport unit 33 Load Lock Chamber 34 Transport Room 36 Nitrogen gas supply unit 37 Process gas supply unit 41 Joining equipment 60 Transport area (example of exterior) W1 Upper wafer (an example of the first substrate) W2 Lower wafer (an example of the second substrate) W1j Joint surface (example of surface) W2j joint surface (example of surface)

Claims

1. a surface modification device for modifying the surfaces of the first substrate and the second substrate; a bonding device that bonds the first substrate and the second substrate modified by the surface modification device by intermolecular forces; Equipped with The surface modification device includes: a surface modification unit for modifying the surfaces of the first substrate and the second substrate one by one; a transport unit that transports the first substrate or the second substrate between an outside and the surface modification unit while being isolated from an external atmosphere; a process gas supply unit for supplying a process gas containing moisture to the inside of the transport unit; Joining system.

2. the transfer unit has a load lock chamber configured so that the inside pressure can be adjusted from atmospheric pressure to a pressure lower than atmospheric pressure; The process gas supply unit supplies the process gas to the load lock chamber. The joint system of claim 1 .

3. A control unit for controlling each unit is further provided. The control unit supplies the processing gas to the load lock chamber by the processing gas supply unit when the first substrate and the second substrate, the surfaces of which have been modified by the surface modification unit, are carried into the load lock chamber. The joint system of claim 2 .

4. The surface modification apparatus further includes a nitrogen gas supply unit for supplying nitrogen gas into the load lock chamber. The control unit is a first process of increasing a pressure in the load lock chamber to a given first pressure using only nitrogen gas from the nitrogen gas supply unit after the first substrate and the second substrate, the surfaces of which have been modified in the surface modification unit, are carried into the load lock chamber; and performing a second process of increasing the pressure in the load lock chamber from the first pressure by using the process gas. The joint system of claim 3 .

5. The control unit is pressurizing the load lock chamber with the process gas to a second predetermined pressure during the second process; and a third process of increasing the pressure in the load lock chamber from the second pressure to atmospheric pressure using only the nitrogen gas from the nitrogen gas supply unit. The joint system of claim 4.

6. a surface hydrophilization device for hydrophilizing the surfaces of the first substrate and the second substrate modified by the surface modification device. The joint system according to any one of claims 1 to 4.

7. a surface modification step of modifying the surfaces of the first substrate and the second substrate; a bonding step of bonding the first substrate and the second substrate modified in the surface modification step by intermolecular forces; Including, The surface modification step includes contacting a moisture-containing process gas with the surface of the first substrate or the second substrate before the first substrate or the second substrate, the surface of which has been modified, is brought into contact with the air. Joining method.

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