Substrate bonding method and substrate bonding system

Abstract

The present invention suppresses adhesion of particles to a substrate surface before bonding substrates to each other.　Provided is a substrate bonding method for bonding substrates including a dielectric surface in at least a part of a bonding surface, the method comprising: a step for preparing a first substrate having a first bonding surface including a dielectric surface in at least a part thereof; a step for immersing at least the first bonding surface of the first substrate in a liquid; a step for subjecting the first bonding surface of the first substrate to underwater plasma treatment in a state where the first bonding surface is immersed in the liquid; a step for preparing a second substrate having a second bonding surface including a dielectric surface in at least a part thereof; and a step for affixing the first bonding surface of the first substrate subjected to the underwater plasma treatment onto the second bonding surface of the second substrate.

Description

Substrate bonding method and substrate bonding system

[0001] The present invention relates to a substrate bonding method and a substrate bonding system for bonding substrates together.

[0002] A known method for bonding substrates such as semiconductor wafers is to activate the bonding surfaces of the substrates by gas plasma treatment, then introduce OH groups into the substrate surfaces, and bond the substrates together through van der Waals forces and hydrogen bonds (intermolecular forces). In this method, OH groups are introduced into and cleaned from the activated substrate surfaces / bonding surfaces using pure water. Note that OH groups can also be introduced by exposing the substrate surfaces to water vapor in the atmosphere. For example, Patent Document 1 and Non-Patent Document 1 describe a method in which substrate surfaces are activated by gas plasma treatment, then hydrophilized, and then bonded together.

[0003] Japanese Patent Application Laid-Open No. 2019-186288

[0004] Fumihiro Inoue et al., “Area-Selective Electroless Deposition of Cu for Hybrid Bonding,” IEEE ELECTRON DEVICE LETTERS, VOL. 42, NO. 12, pp. 1826-1829, DECEMBER 2021

[0005] In the methods described in Patent Document 1 and Non-Patent Document 1, the substrate surfaces are exposed to the atmosphere after plasma activation, raising concerns about contamination of the substrate bonding surfaces in the atmosphere. For example, there is a risk of particles adhering or adhering to the substrate surfaces in the plasma processing chamber and during transfer of the substrates from the plasma processing chamber to the hydrophilization processing chamber. If a substrate with particles adhering or adhering to the bonding surface is bonded to another substrate, there is a risk of a decrease in the adhesive strength between the substrates. An object of the present invention is to solve at least part of the above-mentioned problems. One object of the present invention is to suppress particle adhesion to the substrate surfaces before bonding the substrates.

[0006] According to one aspect of the present invention, there is provided a substrate bonding method for bonding substrates each having a dielectric surface on at least a portion of their bonding surfaces, the method comprising: preparing a first substrate having a first bonding surface having a dielectric surface on at least a portion thereof; immersing at least the first bonding surface of the first substrate in a liquid; subjecting the first bonding surface of the first substrate to an underwater plasma treatment while the first bonding surface is immersed in the liquid; preparing a second substrate having a second bonding surface having a dielectric surface on at least a portion thereof; and bonding the first bonding surface of the first substrate that has been subjected to the underwater plasma treatment to the second bonding surface of the second substrate.

[0007] Schematic diagrams of substrates to be bonded. Schematic diagrams of substrates to be bonded. Schematic diagrams explaining the state of metal surfaces of substrates. Schematic diagrams explaining types of substrates to be bonded. Schematic diagrams explaining types of substrates to be bonded. Schematic diagrams showing a flow of substrate bonding according to an embodiment. Schematic diagrams showing a flow of substrate bonding according to an embodiment. Flowchart showing a flow of substrate bonding according to an embodiment. Schematic diagrams showing a flow of film formation processing and polishing processing for substrates. Schematic diagram of a substrate bonding system according to an embodiment. Schematic diagram of a substrate bonding system according to an embodiment. Schematic diagram of a substrate bonding system according to an embodiment. Plan view of a substrate bonding system according to an embodiment. Side view of a substrate bonding system according to an embodiment. Cross-sectional view of an underwater plasma processing module according to an embodiment. Cross-sectional view of an underwater plasma processing module according to an embodiment. Cross-sectional view of an underwater plasma processing module according to an embodiment. Cross-sectional view of a plasma generator according to an embodiment. Cross-sectional view of a plasma generator according to an embodiment. Top cross-sectional view of a ring nozzle according to an embodiment. Top cross-sectional view of a ring nozzle according to an embodiment. Side cross-sectional view of a ring nozzle according to an embodiment. An explanatory diagram explaining generation of active species at a gas-liquid interface. Flowchart showing a flow of underwater plasma processing according to an embodiment. 1 is a cross-sectional view of an underwater plasma processing module that controls plasma based on an optical emission spectrum, and FIG. 2 is a flowchart showing a flow of plasma control based on an optical emission spectrum.

[0008] An embodiment of the present invention will be described below with reference to the drawings. In the following embodiments, identical or corresponding components are designated by the same reference numerals, and redundant description will be omitted. Furthermore, expressions such as "upper," "lower," "left," and "right" are used in this specification, but these are for the sake of convenience and indicate positions and directions on the paper surface of the illustrative drawings, and may differ in actual placement when the device is in use, etc.

[0009] This embodiment relates to the bonding of substrates having bonding surfaces including at least a dielectric surface. Figures 1A and 1B show schematic diagrams of the substrates to be bonded. Figure 2 shows a schematic diagram illustrating the state of the metal surfaces of the substrates. Figures 3A and 3B show schematic diagrams illustrating the types of substrates to be bonded.

[0010] 1A shows an example of bonding substrates Wf1 and Wf2, each having a bonding surface including only a dielectric surface. In the figure, the substrate Wf1 has a substrate body 11 and a dielectric film (dielectric surface) 12 formed on the substrate body 11. The substrate body 11 includes any base material, such as Si, and may or may not have an electronic circuit formed thereon. In this example, the bonding surface of the substrate Wf1 includes only the dielectric surface 12. As shown in FIG. 1A, the substrate Wf2 also has a similar configuration to the substrate Wf1. In this case, when the substrates Wf1 and Wf2 are bonded, the dielectric surfaces 12 of the substrates Wf1 and Wf2 are bonded to each other.

[0011] 1B shows an example of bonding substrates that further include a region made of a metal material adjacent to the dielectric region (so-called hybrid bonding). In the figure, the substrate Wf1 has a substrate body 11 and a dielectric film (dielectric surface) 12 and a metal film (metal surface) 13 formed on the substrate body 11. As shown in FIG. 1B, the substrate Wf2 also has a similar configuration to the substrate Wf1. In this case, when the substrates Wf1 and Wf2 are bonded, the dielectric surfaces 12 of the substrates Wf1 and Wf2 are bonded to each other, and the metal surfaces 13 of the substrates Wf1 and Wf2 are bonded to each other.

[0012] The material of the dielectric film (dielectric surface) 12 is a silicon oxide film (SiO ２), silicon carbonitride (SiCN), silicon carbonate (SiCO), silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), aluminum gallium nitride (AlGaN), or any other dielectric material used in semiconductor manufacturing processes, panel manufacturing processes, etc.

[0013] The material of the metal film (metal surface) 13 may be copper (Cu) or any other metal material used in semiconductor manufacturing processes, panel manufacturing processes, and the like.

[0014] In this embodiment, at least one of the substrates to be bonded is subjected to surface treatment (surface activation treatment and surface hydrophilization treatment) using underwater plasma treatment. The surface activation treatment is a treatment to form dangling bonds on the dielectric surface by plasma treatment or the like. The surface hydrophilization treatment is a treatment to modify the dielectric surface with OH groups.

[0015] In other words, the surface treatment by underwater plasma treatment according to this embodiment (surface activation treatment and surface hydrophilization treatment) may be performed on the bonding surfaces of both substrates to be bonded, or may be performed on only the bonding surface of one of the substrates. When the surface treatment by underwater plasma treatment is performed on only one of the substrates, the other substrate may be subjected to another surface treatment (such as a surface treatment including a dry plasma treatment), or may not be subjected to a plasma treatment.

[0016] As shown in Figure 2, the surface of the substrate to be joined may be such that the metal surface 13 is convex relative to the dielectric surface 12 (Figure 2(a)), such that the metal surface 13 is flush with the dielectric surface 12 (Figure 2(b)), or such that the metal surface 13 is concave relative to the dielectric surface 12 (Figure 2(c)).

[0017] The substrates Wf1 and Wf2 can be bonded together by wafer bonding (FIG. 3A). That is, the substrates Wf1 and Wf2 can be wafers.

[0018] Furthermore, one of the substrates to be bonded may be a die (chip) obtained by dividing a wafer ( FIG. 3B ). That is, one of the substrates Wf1 and Wf2 may be a wafer, and the other may be a die. Furthermore, both of the substrates to be bonded may be dies obtained by dividing a wafer. That is, both the substrate Wf1 and the substrate Wf2 may be dies.

[0019] Alternatively, a substrate may be one in which a plurality of individual dies are attached (pasted) to a tape frame. That is, one of the substrate Wf1 and the substrate Wf2 may be one in which a plurality of dies are attached to a tape frame, and the other may be a die.

[0020] Alternatively, a laminated substrate in which a plurality of substrates have already been bonded together may be used, that is, the substrate Wf1 and / or the substrate Wf2 may be a laminated substrate in which a plurality of substrates have already been bonded together.

[0021] 4 is a schematic diagram showing the flow of substrate bonding according to one embodiment. This example illustrates the bonding (hybrid bonding) of a substrate Wf having a bonding surface including a dielectric surface 12 and a metal surface 13. In this specification, any of the substrates Wf1 and Wf2 may be referred to as the substrate Wf.

[0022] The example of FIG. 4 shows a case where the substrate Wf (Wf1 and / or Wf2) is subjected to a polishing process prior to surface treatment (surface activation process and surface hydrophilization process). In a CMP apparatus, the substrate Wf is subjected to a polishing process (CMP), a cleaning process, and a drying process. The polishing process, cleaning process, and drying process are performed, for example, in a polishing module, a cleaning module, and a drying module, respectively, within the CMP apparatus. This example shows a case where the metal surface 13 becomes recessed from the dielectric surface 12 due to dishing during CMP processing. In FIG. 4, "Roll" indicates cleaning with a roll-shaped sponge, "Pen" indicates cleaning with a pencil-shaped sponge, and "2FJ" indicates cleaning with a two-fluid nozzle. The same applies to FIG. 5.

[0023] As shown in Fig. 4, the substrate Wf after processing by the CMP apparatus is subjected to surface treatment (surface activation treatment and surface hydrophilization treatment). In this surface treatment, the surface activation treatment and surface hydrophilization treatment are performed in the same chamber and in the same process by underwater plasma treatment. In this underwater plasma treatment, the bonding surface of the substrate Wf is plasma-treated while the bonding surface of the substrate Wf is immersed in a liquid (treatment liquid). As shown in Fig. 4, in the surface activation treatment, dangling bonds are formed on the bonding surface of the substrate. In the hydrophilization treatment, the bonding surface of the substrate is modified with OH groups.

[0024] According to the underwater plasma treatment, the substrate Wf can be subjected to the surface activation treatment and the hydrophilization treatment in the same process (one process) while being kept in a wet state, and therefore the adhesion or fixation of particles to the substrate Wf can be suppressed. Moreover, since the underwater plasma treatment is performed while the substrate Wf is immersed in a liquid, the underwater plasma treatment may also serve as a cleaning treatment for cleaning the substrate Wf (particularly the bonding surface) with the liquid.

[0025] The surface treatment (underwater plasma treatment) is performed, for example, in an underwater plasma treatment module. The underwater plasma treatment module may be included in a CMP apparatus, a bonding apparatus that performs the bonding step, or an underwater plasma treatment apparatus that is independent of the CMP apparatus and the bonding apparatus.

[0026] The substrates Wf1 and Wf2 are subjected to surface activation and surface hydrophilization treatment using underwater plasma treatment, and then bonded together. At this time, the dielectric surfaces 12 of the substrates Wf1 and Wf2 are bonded together by intermolecular forces (van der Waals forces, hydrogen bonds). Meanwhile, because the metal surfaces 13 of the substrates Wf1 and Wf2 are concave, gaps exist between the metal surfaces 13 of the substrates Wf1 and Wf2 at this stage.

[0027] The bonded substrates Wf1 and Wf2 are then subjected to a heat treatment (annealing treatment), which expands the metal surfaces 13 of the substrates Wf1 and Wf2 and bonds the metal surfaces 13 of the substrates Wf1 and Wf2 together by metal diffusion bonding. Furthermore, the annealing treatment removes moisture from the dielectric surfaces 12 of the substrates Wf1 and Wf2, forming Si—O bonds and / or Si—Si bonds between the bonding surfaces, firmly bonding the bonding surfaces together. In this manner, the substrates Wf1 and Wf2 are bonded together.

[0028] The bonding step and the annealing step can be performed, for example, in a bonding module and an annealing module in a bonding apparatus. The bonding step and the annealing step may be performed in the bonding module in a bonding apparatus.

[0029] In FIG. 4, after the surface treatment (surface activation treatment and surface hydrophilization treatment) is performed on the substrate Wf, the substrate Wf may be subjected to a drying treatment before the bonding step.

[0030] Furthermore, in the underwater plasma treatment, the liquid used as the treatment liquid may be degassed, which reduces the concentration of dissolved oxygen in the liquid and suppresses oxidation of the metal surface.

[0031] In addition, in order to improve the bonding strength between the substrates, the liquid used as the processing liquid contains a small amount of hydrogen fluoride (HF) and ammonium hydroxide (NH ４ An additive containing at least one of substances such as CF, ... ４ , N.F. ３ , SF ６ , N.H. ３ One or more of the following components can be added:

[0032] 5 is a schematic diagram showing a flow of substrate bonding according to one embodiment. In this example, an underwater plasma processing module for performing surface treatment is incorporated into a CMP apparatus or is in-line connected to the CMP apparatus. In the CMP apparatus, the substrate Wf is subjected to a polishing process (CMP), a cleaning process, a surface treatment (surface activation process and surface hydrophilization process), and a drying process. In the underwater plasma treatment, the substrate is immersed in a liquid (treatment liquid) to achieve a cleaning effect simultaneously with surface activation and surface hydrophilization, so that post-polishing cleaning (post-CMP cleaning in the figure) may be omitted or simplified.

[0033] According to this configuration, the polishing process and the underwater plasma treatment can be performed in the polishing apparatus while keeping the substrate wet, thereby preventing particles from adhering or adhering to the substrate due to drying of the substrate.

[0034] 5, a CMP apparatus (a CMP apparatus incorporating an underwater plasma processing module) and a bonding apparatus (a bonding module and / or an annealing module) may be further in-line connected. Furthermore, the CMP apparatus and the underwater plasma processing module may be in-line connected, and the underwater plasma processing module and the bonding apparatus (a bonding module and / or an annealing module) may also be in-line connected.

[0035] In the configuration of FIG. 4, the CMP apparatus and the underwater plasma processing module and / or the underwater plasma processing module and the bonding apparatus (bonding module and / or annealing module) may be connected in-line.

[0036] In FIG. 5 , to prevent the substrate from drying out during transport, an anti-drying module may be provided in the substrate transport path between the CMP process and the post-CMP cleaning process, between the post-CMP cleaning process and the underwater plasma treatment process, and / or between the underwater plasma treatment process and the drying process. Examples of anti-drying modules include those that supply liquid to the substrate during transport, those that immerse the substrate in liquid during transport, those that humidify the air in the transport path (air around the substrate), and any other method to prevent the substrate from drying out during transport. Specifically, (1) the above method can be implemented using a liquid supply nozzle or the like. (2) A tank for immersing the substrate may be provided on the transport robot. Furthermore, in a load lock chamber, the substrate support stage may serve as a tank for storing liquid. (3) The entire transport path may serve as a tank for storing liquid, and the substrate may be transported immersed in the liquid. (4) Humidified air using a humidifier or the like may be supplied to the transport path. (5) A liquid may be placed in the transport path and humidified by evaporation of the liquid. (6) In addition to the above, any method may be used to prevent the substrate from drying out along the transport path. The liquid used in the anti-drying module may be a degassed liquid. By using a degassed liquid, oxidation of the metal surface of the substrate can be suppressed. In particular, when a liquid is supplied by the anti-drying module, for example, in a load lock chamber of an underwater plasma processing module, it is preferable to use a degassed liquid. The liquid used in the anti-drying module may be, for example, pure water.

[0037] In Fig. 4, an anti-drying module may be provided on the substrate transport path between the CMP step and the post-CMP cleaning step, between the post-CMP cleaning step and the drying step, and / or between the surface treatment step and the bonding step. In addition, when a step is added in Figs. 4 and 5, a similar anti-drying module may be provided on the transport path between each step.

[0038] (Flowchart of substrate bonding process) Fig. 6 is a flowchart showing the flow of substrate bonding according to one embodiment. Fig. 7 is a schematic diagram showing the flow of film formation and polishing processes on substrates. Here, an example is shown in which a substrate Wf1 is subjected to film formation and polishing processes, and then subjected to underwater plasma treatment, and then bonded to another substrate Wf2. The other substrate Wf2 may or may not be subjected to underwater plasma treatment, or other surface treatment (dry plasma treatment, hydrophilization treatment).

[0039] In step S11, the dielectric surface 12 of the substrate Wf1 is subjected to a process such as etching to form an opening in the dielectric surface 12 (FIG. 7A).

[0040] In step S12, a thin film 14 (barrier layer, seed layer, etc.) is formed on the surface of the substrate Wf1 using a method such as PVD, CVD, or ALD (FIG. 7B).

[0041] In step S13, metal is deposited in the openings of the substrate Wf1 by plating or other methods (FIG. 7C). A step of cleaning the substrate after film formation may also be provided.

[0042] In step S14, the surface of the substrate Wf1 is subjected to a polishing process such as CMP (FIG. 7(d)). As a result, a surface (bonding surface) including a dielectric surface 12 and a metal surface 13 is formed on the substrate Wf1. A process of cleaning the substrate after polishing may be added. In addition to cleaning, an example of an additional process may include a process of processing the outer periphery (edge ​​and bevel) of the substrate. For example, the edge and bevel may be polished / ground with a grinding stone while supplying pure water. Also, a process of wet etching the dielectric film (to make the metal film protrude from the dielectric film) may be added.

[0043] In step S15, the bonding surface of the substrate Wf1 is subjected to surface activation and surface hydrophilization by underwater plasma treatment (see FIGS. 4 and 5). The underwater plasma treatment simultaneously activates and hydrophilizes the surface of the substrate.

[0044] In step S16, the bonding surface of the substrate Wf1 is bonded to the bonding surface of another substrate Wf2 (see FIGS. 4 and 5).

[0045] In step S17, the bonded substrates Wf are subjected to an annealing treatment to complete the bonding of the substrates Wf (see FIGS. 4 and 5).

[0046] Steps S14 to S15 (polishing to hydrophilization) can be performed while the bonding surfaces of the substrates are kept continuously wet. Steps S13 to S15 (plating to hydrophilization) may also be performed while the bonding surfaces of the substrates are kept continuously wet.

[0047] The flowchart in FIG. 6 is an example, and the present invention is not limited to the configuration of the flowchart shown in the figure.

[0048] (Configuration Example of Substrate Bonding System) FIG. 8A is a schematic diagram of a substrate bonding system according to one embodiment. The substrate bonding system shown in FIG. 8A includes a first apparatus (polishing apparatus 200) and a second apparatus (bonding apparatus 400). A substrate Wf on which an electronic circuit has been formed and other processes has been carried into the first apparatus. After being processed by the first apparatus, the substrate Wf is further processed by the second apparatus. As shown in FIG. 8A , the first apparatus includes a polishing module 206 and a cleaning module 208. The first apparatus may also include a plating module 700. The plating module 700 may be omitted from the first apparatus. The second apparatus includes an underwater plasma treatment module 340 and a bonding module 410. In this configuration, the substrate Wf is transported between the first apparatus and the second apparatus in a cassette, such as a FOUP.

[0049] 8B is a schematic diagram of a substrate bonding system according to one embodiment. In this example, the output of a first apparatus (polishing apparatus 200) and the input of a second apparatus (bonding apparatus 400) are connected inline, and the substrate Wf is transported inline from the first apparatus to the second apparatus while being kept wet. This configuration effectively prevents particles from adhering to the substrate Wf during transport between the first and second apparatuses (in this example, between the cleaning module 208 of the first apparatus and the underwater plasma processing module 340 of the second apparatus).

[0050] 8C is a schematic diagram of a substrate bonding system according to one embodiment. In this example, an underwater plasma treatment module 340 is incorporated into a first apparatus (polishing apparatus 200), and the underwater plasma treatment module 340 of the first apparatus is connected in-line to a bonding module 410 of a bonding apparatus 400. The substrate Wf is in-line transported from the first apparatus to the second apparatus while being kept wet. This configuration can prevent particles from adhering to the substrate Wf during transport between the underwater plasma treatment module 340 of the first apparatus and the bonding module 410 of the second apparatus.

[0051] (Specific Configuration Example of Substrate Bonding System) Figure 9 is a plan view of a substrate bonding system according to an embodiment. Figure 10 is a side view of the substrate bonding system according to an embodiment.

[0052] The substrate bonding system 100 includes a polishing apparatus 200, an underwater plasma processing apparatus 300, and a bonding apparatus 400. In this embodiment, the polishing apparatus 200 and the underwater plasma processing apparatus 300 are connected in-line at a carry-in section 310. The underwater plasma processing apparatus 300 and the bonding apparatus 400 are connected in-line at an unloading section 320. The substrate bonding system 100 also includes a control module 220 that controls each section of the system.

[0053] The control module 220 may be configured to include a memory (not shown) that stores various setting data such as machine parameters and various programs, and a CPU (not shown) that executes the programs stored in the memory. The control module 220 may also include an input / output interface that includes an output device such as a display, and input devices such as a keyboard and a mouse. The storage medium constituting the memory may include any volatile storage medium and / or any non-volatile storage medium. The storage medium may include one or more of any storage medium, such as a ROM, RAM, flash memory, hard disk, CD-ROM, DVD-ROM, or flexible disk. Some or all of the functions of the control module 220 may be configured using hardware such as an ASIC. Some or all of the functions of the control module 800 may be configured using a PLC, sequencer, or the like. Some or all of the control module 220 may be located inside and / or outside the housing of the polishing apparatus 200, the underwater plasma treatment apparatus 300, and / or the bonding apparatus 400. Some or all of the control module 220 is communicatively connected to each part of the substrate bonding system 100 via wires and / or wirelessly.

[0054] The polishing apparatus 200 includes one or more (four in this example) load ports 201, an EFFEM 202, linear transporters 204 and 205, one or more (four in this example) polishing modules 206, and one or more cleaning modules 208. A cassette (e.g., a FOUP) capable of storing a plurality of substrates is placed on each load port 201. A transfer robot 203 is disposed in the EFFEM 202, and the transfer robot 203 is configured to be movable along the row of cassettes on a traveling mechanism (not shown). The transfer robot 203 removes a substrate from the cassette and transfers the substrate to the linear transporter 204 via a lifter (not shown).

[0055] The linear transporter 204 is arranged along two polishing modules 206 (polishing modules 206A and 206B) close to the loading side, and transports the substrates received from the transport robot 203 to a plurality of transport positions. The two polishing modules 206 close to the loading side receive the substrates at predetermined transport positions of the linear transporter 204, polish the substrates, and then return the substrates to the same or another transport position of the linear transporter 204.

[0056] A swing transporter 207 is disposed between the linear transporter 204, the linear transporter 205, and the transfer robot 210. The swing transporter 207 has a hand that can move between the linear transporter 204, the linear transporter 205, and the transfer robot 210, and the transfer of substrates among these is performed by the swing transporter 207.

[0057] The linear transporter 205 is arranged along two polishing modules 206 (polishing modules 206C and 206D) farthest from the loading side, and transports substrates received from the swing transporter 207 to multiple transfer positions. The two polishing modules 206 farthest from the loading side receive substrates at predetermined transfer positions on the linear transporter 205, polish the substrates, and then return the substrates to the same or another transfer position on the linear transporter 205. Each polishing module 206 can have a known configuration in which a top ring holds the substrate, and a polishing liquid is supplied onto a polishing pad while the substrate and polishing pad are rotated and brought into contact with each other for polishing.

[0058] The substrates polished in one or more of the polishing modules 206A to 206D are transferred to the transfer robot 210 by the swing transporter 207 and then cleaned in one or more cleaning modules 208. In this example, two cleaning modules 208 are shown, but any number of cleaning modules 208 may be provided. After the cleaning process, the substrates are transported to the underwater plasma processing apparatus 300 by the transfer robot 211.

[0059] The underwater plasma treatment apparatus 300 includes a loading section 310, a treatment section 330 in which one or more (two in this embodiment) underwater plasma treatment modules 340 are arranged, and an unloading section 320. The treatment section 330 (underwater plasma treatment module 340) is inline connected to the polishing apparatus 200 via the loading section 310, and is inline connected to the bonding apparatus 400 via the unloading section 320. The number of underwater plasma treatment modules 340 may be one, or three or more. Details of the underwater plasma treatment module 340 will be described later.

[0060] The loading section 310 is configured as a load lock chamber, has a configuration in which the chamber is sealed and the pressure therein can be adjusted. The loading section 310 has gates (not shown) on the polishing apparatus 200 side and the processing section 330 side, and substrates are transferred between the polishing apparatus 200 and the processing section 330 (underwater plasma processing module 340) by opening and closing the gates. When the underwater plasma processing module 340 is depressurized, the loading section 310 is also depressurized to the same level of pressure. Note that if there is no need to depressurize the loading section 310, the loading section 310 does not need to be configured as a load lock chamber.

[0061] A stage 311 on which a substrate is placed is disposed in the loading section 310, and the stage 311 is configured to be movable along a traveling mechanism 312. The stage 311 is configured to move along the traveling mechanism 312 between a position where the substrate is received from the polishing apparatus 200 (transfer robot 211) and a position where the substrate is handed over to the underwater plasma processing module 340.

[0062] An anti-drying module 313 (not shown) is installed in the loading section 310, and the anti-drying module 313 keeps the substrates in the loading section 310 wet. The anti-drying module 313 can be, for example, a mechanism for supplying liquid to the substrates during transport, a mechanism for immersing the substrates in liquid during transport, a mechanism for humidifying the air in the transport path, a combination of two or more of these, or any other mechanism for preventing the substrates from drying out during transport. Specifically, the above mechanism can be realized using any of the configurations (1) to (6) described above with reference to FIG. 5. Note that the anti-drying module 313 may be omitted in some cases.

[0063] The processing section 330 is provided with a transfer robot (for loading) (not shown) for receiving the substrate from the stage 311 of the loading section 310 and loading the substrate into the underwater plasma processing module 340. The processing section 330 is also provided with a transfer robot (for unloading) (not shown) for receiving the substrate from the underwater plasma processing module 340 and transferring the substrate to the stage 321 of the unloading section 320. The substrate on the stage 311 of the loading section 310 is loaded into the underwater plasma processing module 340 by the transfer robot (for loading) (not shown). The substrate that has been subjected to underwater plasma processing in the underwater plasma processing module 340 is transferred to the stage 321 of the unloading section 320 by the transfer robot (for unloading) (not shown). Note that the stages 311, 321 of the loading section 310 and the unloading section 320 may themselves be transfer robots having hands for supporting the substrate. In this case, the transfer robot (not shown) in the processing section 330 can be omitted, and the transfer robots (311, 321) directly transfer substrates into and out of the underwater plasma processing module.

[0064] In the underwater plasma treatment module 340, the substrate may be subjected to a dry plasma treatment prior to the underwater plasma treatment. In this case, the substrate may be subjected to a drying treatment prior to the dry plasma treatment. The drying treatment prior to the dry plasma treatment may be performed by providing a drying module in the polishing apparatus 200, or by providing a drying module in the underwater plasma treatment apparatus 300. In the underwater plasma treatment module 340, the substrate may be subjected to a cleaning treatment using pure water or the like after the underwater plasma treatment of the substrate. In the underwater plasma treatment module 340, the substrate may be subjected to a drying treatment after the underwater plasma treatment or after cleaning of the substrate. A drying module separate from the underwater plasma treatment module 340 may be provided to perform the drying treatment on the substrate. The drying treatment of the substrate may include, for example, rotating the substrate under atmospheric pressure or reduced pressure.

[0065] The unloading unit 320 is configured as a load lock chamber, has a configuration in which the chamber is sealed and the pressure therein can be adjusted. The unloading unit 320 has gates (not shown) on the processing unit 330 side and the bonding apparatus 400 side, and substrates are transferred between the processing unit 330 (underwater plasma processing module 340) and the bonding apparatus 400 by opening and closing the gates. When the underwater plasma processing module 340 is depressurized, the unloading unit 320 is also depressurized to the same degree of pressure. Note that if it is not necessary to depressurize the unloading unit 320, the unloading unit 320 does not have to be configured as a load lock chamber.

[0066] A stage 321 on which a substrate is placed is disposed in the unloading section 320, and the stage 321 is configured to be movable along a traveling mechanism 322. The stage 321 is configured to move along the traveling mechanism 322 between a position where the substrate is received from the underwater plasma processing apparatus 300 and a position where the substrate is delivered to the bonding apparatus 400. An anti-dry module 323 similar to the anti-dry module 313 in the loading section 310 is disposed in the unloading section 320. However, the anti-dry module 313 and the anti-dry module 323 do not need to have the same configuration. The anti-dry module 323 may be omitted in some cases.

[0067] The bonding apparatus 400 is in-line connected to the processing section 330 of the underwater plasma processing apparatus 300 via the unloading section 320. In this embodiment, the bonding apparatus 400 includes a bonding module 410 and a transfer robot 420. In this embodiment, the bonding apparatus 400 includes one bonding module, but may include multiple bonding modules 410. The transfer robot 420 receives the substrates on the stage 321 of the unloading section 320 and transfers them into the bonding module 410. The bonding module 410 has the function of bonding two substrates together and the function of performing an annealing treatment on the bonded substrates. For example, the bonding module 410 can be configured to include a chuck that holds each of the two substrates and a drive mechanism that moves the chuck to bond the two substrates together. The bonding module 410 can also be configured to include a heater for the annealing treatment.

[0068] An annealing module for annealing treatment may be provided in the bonding apparatus 400 separately from the bonding module 410, or an annealing apparatus for annealing treatment may be provided inside or outside the bonding apparatus 400. When an annealing apparatus is provided outside the bonding apparatus 400, it is preferable to connect the bonding apparatus and the annealing apparatus in-line.

[0069] Since this substrate bonding system 100 includes multiple underwater plasma treatment modules 340, the first and second substrates (substrate Wf1, substrate Wf2) to be bonded together may be subjected to underwater plasma treatment (surface activation treatment, surface hydrophilization treatment) at the same time in the first and second underwater plasma treatment modules 340 among the multiple underwater plasma treatment modules 340. In this case, the bonding surfaces of both substrates Wf1 and Wf2 to be bonded together can be treated at the same time, making this method more suitable for bonding. In other words, since the substrates Wf1 and Wf2 are not left unattended before bonding, it is possible to suppress or prevent contamination of the bonding surfaces of the substrates Wf1 and Wf2.

[0070] In the illustrated example, two underwater plasma treatment modules 340 are arranged on a horizontal plane, but they may be stacked vertically. In the illustrated example, two underwater plasma treatment modules 340 are provided, but one, or three or more underwater plasma treatment modules 340 may be provided. Note that the two substrates to be bonded together may be treated sequentially in the same underwater plasma treatment module 340. In this case, the number of underwater plasma treatment modules 340 may be one.

[0071] 10, a transfer line 450 may be provided to return the substrate from the bonding apparatus 400 to the EFEM 202. The transfer space constituting this transfer line 450 is preferably isolated from the polishing / cleaning modules 206 and 208. The transfer device provided on the transfer line 450 may be a linear transporter or other known transfer device.

[0072] 11 is a cross-sectional view of an underwater plasma processing module according to one embodiment. The underwater plasma processing module 340 mainly includes a chamber 341, a stage 600, and a plasma generator (plasma generating unit) 500.

[0073] The chamber 341 is provided with a gas inlet 342 for introducing a process gas 540 via a fluid line 345, a gas outlet 343 for exhausting the process gas 540 from the chamber 341 via a fluid line 346, and an outlet 344 for exhausting the process liquid 650 from the chamber 341 to a circulation line 348. A pump 347 is disposed on the fluid line 346, and the process gas 540 is exhausted from the chamber 341 by the pump 347. The pressure in the chamber 341 may be reduced arbitrarily by balancing the exhaust flow rate of the pump 347 and the inflow flow rate of the process gas 540. The inner walls of the chamber 341 may be anodized, coated with TiN, or coated with a ceramic film to protect against plasma damage and electromagnetic noise.

[0074] The stage 600 includes a disk-shaped mounting portion having a mounting surface for the substrate Wf and a rotation axis provided at the center of the lower surface of the mounting portion. The upper surface of the mounting portion of the stage 600 forms the mounting surface on which the substrate Wf is placed. The stage 600 is equipped with an electrostatic chuck mechanism, an adsorption mechanism, etc., and is configured to electrostatically chuck or adsorb and fix the substrate Wf using the electrostatic chuck mechanism, adsorption mechanism, etc. When a high-frequency power supply and an electrostatic chuck are combined, the stage 600 cannot be at ground potential. Therefore, when the stage 600 is connected to a high-frequency power supply, the substrate Wf is adsorbed and fixed to the stage 600. This is because when a high-frequency power supply and an electrostatic chuck are combined, dielectric loss due to the ceramic of the electrostatic chuck increases.

[0075] The rotation axis of the stage 600 is connected to a drive mechanism (not shown), allowing the stage 600 to rotate and move up and down. The drive mechanism can be a known actuator such as a motor, a rack and pinion, or a ball screw. The stage 600 may be configured to rotate eccentrically via a cam mechanism or the like. The plasma generator 500 is similarly connected to a drive mechanism (a known actuator such as a motor, a rack and pinion, or a ball screw, or a cam mechanism) (not shown), and is configured to rotate, move up and down, and / or rotate eccentrically.

[0076] The rotational movement of the plasma generator 500 and / or the stage 600 can disperse and homogenize the plasma concentration area. The elevation movement of the plasma generator 500 and / or the stage 600 can adjust the distance between the plasma generator 500 (electrode 503) and the substrate Wf. When the plasma region (plasma 550) is smaller than the substrate Wf, the eccentric rotation of the plasma generator 500 and / or the stage 600 can bring the plasma region into contact with the entire substrate Wf.

[0077] One or more flow channels 603 are provided in the wall surface of a cylindrical portion 602 provided on the outer periphery of the stage 600 , and the flow channels 603 are fluidly connected to the circulation line 348 .

[0078] A ring nozzle 604 is disposed on the upper surface of the mounting portion of the stage 600 so as to surround the substrate Wf. The ring nozzle 604 has a height greater than the height of the substrate Wf on the stage 600. That is, the processing liquid 650 accumulated inside the ring nozzle 604 completely covers the surface (bonding surface) of the substrate Wf, allowing the substrate Wf to be immersed in it. A flow path 605 is formed inside the ring nozzle 604 and is fluidly connected to a flow path 603 inside the cylindrical portion 602 of the stage 600, and a nozzle opening 605A is provided at the outlet of the flow path 605. The processing liquid 650 is discharged from the nozzle opening 605A.

[0079] The mounting portion of the stage 600 is provided with a discharge hole 601 that penetrates from the upper surface to the lower surface. The processing liquid 650 discharged from the ring nozzle 604 toward the substrate Wf immerses the substrate Wf and is then discharged from the discharge hole 601 to the lower part of the mounting portion of the stage 600. The discharged processing liquid 650 accumulates at the bottom of the chamber 341 and is discharged from the discharge port 344 to the circulation line 348. The inside and outside of the cylindrical portion 602 are fluidly connected by a flow path (not shown).

[0080] The processing liquid 650 discharged from the outlet 344 is returned to the ring nozzle 604 (flow path 605) via the circulation line 348 and the flow path 603 in the stage 600 by a pump 349 provided in the circulation line 348. Note that new processing liquid is supplied to the circulation line 348 from a supply path (not shown). New processing liquid may be supplied to the circulation line 348 via a reservoir.

[0081] The stage 600 of this embodiment is made of a conductor, and is connected to a high frequency power supply 351. The stage 600 may also be connected to a ground potential.

[0082] The plasma generator 500 includes a conductive portion (waveguide) 502 and a dielectric portion 501 surrounding the conductive portion 502. The lower end of the conductive portion 502 constitutes an antenna (electrode) 503. The electrode 503 is connected to the high-frequency power supply 350 via the conductive portion 502. An electric field is induced between the electrode 503 and the substrate Wf, thereby generating plasma 550 near the electrode 503. The plasma generator 500 is connected to a drive mechanism (not shown) so that the plasma generator 500 can be rotated and elevated. The drive mechanism can be a known actuator such as a motor, rack and pinion, or ball screw. The stage 600 may be configured to rotate eccentrically via a cam mechanism or the like. By raising and lowering the plasma generator 500 and / or the stage 600, the distance between the electrode 503 and the substrate Wf is adjusted to a predetermined distance (approximately 10 mm).

[0083] In the example of Fig. 11, the electrode 503 is formed in an uneven shape. The electrode 503 may be covered with a dielectric layer 504 as shown in Fig. 14A. An electrode 503 having such a shape is sometimes called a slot antenna. The electrode 503 may also be a radial line slot antenna. Note that the electrode 503 is not limited to an uneven shape and may have any shape.

[0084] The composition of the processing gas 540 is a rare gas (Ar, He, etc.) + H ２ O (gas) and / or H ２ O ２ (gas), and / or H ２ Noble gases are also called inert gases. Noble gases (Ar, He, etc.), H ２ The composition of the processing solution 650 is ultrapure water or H ２ O ２ The pressure in the chamber 341 is preferably equal to or higher than the saturated vapor pressure of water, and can be set to 2 to 101.3 kPa.

[0085] The discharge method can be, for example, CCP (Capacitively Coupled Plasma) or DBD (Dielectric-Barrier Discharge). The stage 600 may be at ground potential. The plasma generator 500 and the stage 600 may be connected to different power supplies, and a different bias may be applied to the substrate.

[0086] The high frequency power supplies 350 and 351 may be high frequency power supplies that output high frequency power of 13.56 MHz to 2.4 GHz. The high frequency power supply 350 and the plasma generator 500 (conductive portion 502) are preferably connected via a matching network (impedance matching device). Similarly, the high frequency power supply 351 and the stage 600 are preferably connected via a matching network (impedance matching device).

[0087] An AC power supply or a DC power supply may be used instead of the high frequency power supply 350 and / or the high frequency power supply 351. Also, a pulse generator may be attached to the DC power supply to apply a voltage / current with a pulse waveform to the plasma generator 500 side and / or the stage 600 side.

[0088] In the underwater plasma treatment module 340 described above, a treatment liquid 650 is supplied from the ring nozzle 604 to the substrate Wf placed on the stage 600, and the surface (bonding surface) of the substrate Wf is immersed in the treatment liquid 650. In addition, a treatment gas 540 is supplied into the chamber 341, and plasma 550 is generated by the plasma generator 500. As a result, for example, underwater plasma treatment (surface activation treatment and hydrophilization treatment) of the substrate Wf is performed as shown in FIGS. 4 and 5 .

[0089] FIG. 12 is a cross-sectional view of an underwater plasma processing module according to one embodiment. In this embodiment, instead of the gas inlet 342 in the configuration of FIG. 11 , a process gas 540 is introduced into a chamber 341 through a gas inlet path 510 provided along a conductive portion (waveguide) 502 in a plasma generator 500. As shown in FIG. 14B , the gas inlet path 510 includes a flow path 511 passing through the conductive portion 502 and a plurality of through-holes 512 penetrating the electrode 503 and forming a gas inlet into the chamber 341. The process gas 540 passes through the gas inlet path 510 in the plasma generator 500 and is introduced into the space between the electrode 503 and the substrate Wf. In this way, by introducing the process gas 540 into the chamber 341 from above, the process gas 540 can be efficiently introduced near the substrate Wf. The other configurations are the same as those of FIG. 11 . In FIGS. 12 and 14B, through-holes 512 are provided in the recesses of electrode 503, but through-holes 512 may be provided in the protrusions of electrode 503, or through-holes 512 may be provided in both the recesses and protrusions.

[0090] Fig. 13 is a cross-sectional view of an underwater plasma processing module according to one embodiment. In this embodiment, an ICP (Inductively Coupled Plasma) discharge method is employed. The configuration of Fig. 13 corresponds to the configuration of Fig. 12, in which the plasma generator 500 is replaced with a plasma generator 500A for ICP. In the configuration of Fig. 11, the plasma generator 500 may also be replaced with a plasma generator 500A for ICP.

[0091] 13, a processing gas 540 is supplied from above to a gas introduction path 510A in a dielectric pipe 505, and a high frequency is applied to a coil 515 to induce an induced current, thereby generating plasma 550 in the form of a plasma jet. The plasma 550 in the form of a plasma jet comes into contact with the liquid surface of a processing liquid 650 covering the surface (bonding surface) of the substrate Wf, and active species (radicals) OH * is generated.

[0092] 11 and 12, the high frequency power supplies 350 and 351 can be high frequency power supplies of 13.56 MHz to 2.4 GHz. It is preferable to connect the high frequency power supply 350 and the coil 515, and the high frequency power supply 351 and the stage 600 via a matching network (impedance matching device). Furthermore, a pulse generator may be attached to the DC power supply to apply a pulse waveform voltage / current to the stage 600.

[0093] In this embodiment, since the area of ​​the plasma 550 is relatively narrow, the plasma generator 500 is preferably configured to be movable up and down, front and back, and / or left and right in order to supply the plasma 550 to the entire surface of the substrate Wf. A known actuator such as a motor, a rack and pinion, or a ball screw can be used as a drive mechanism for moving the plasma generator 500. Note that instead of or in addition to moving the plasma generator 500 up and down, front and back, or left and right, the stage 600 may be rotated or eccentrically rotated.

[0094] (Plasma Generator) Fig. 14A is a cross-sectional view of a plasma generator according to one embodiment. As shown in the figure, a plasma generator 500 can be configured to include a conductive portion (waveguide) 502 and a dielectric portion 501 that covers the periphery of the conductive portion 502. The lower end (on the substrate Wf side) of the conductive portion 502 has an uneven shape, and this portion serves as an electrode 503. The electrode 503 is covered with a dielectric layer 504. An electrode 503 having such a shape is sometimes called a slot antenna.

[0095] Since the electrode 503 is generally circular when viewed from the bottom, the irregularities can be provided on the circular bottom surface in, for example, a grid pattern. The irregularities may also be provided in any other pattern.

[0096] According to this configuration, the electrode 503 has an uneven shape, and thus the discharge threshold voltage can be reduced by concentrating the electric field at the convex portions. Furthermore, the electrode 503 is covered with the dielectric layer 504, which can prevent the electrode 503 from wearing and causing metal contamination inside the chamber 341. Furthermore, by covering the electrode 503 with the dielectric layer 504, the region and shape of the plasma 550 can be stabilized. The electrode 503 is not limited to an uneven shape, and can have any shape.

[0097] 14B is a cross-sectional view of a plasma generator according to one embodiment. This embodiment differs from the configuration shown in FIG. 14A in that a gas inlet path 510 is provided within the plasma generator 500. The gas inlet path 510 includes a flow path 511 passing through the conductive portion 502 and a plurality of through-holes 512 that penetrate the electrode 503 and form gas inlets into the chamber 341. This configuration allows the processing gas 540 to be efficiently supplied to the space between the electrode 503 and the substrate Wf, where the plasma 550 is generated.

[0098] (Ring Nozzle) Fig. 15A is a top cross-sectional view of a ring nozzle according to an embodiment. Fig. 15B is a top cross-sectional view of a ring nozzle according to an embodiment. Fig. 16 is a side cross-sectional view of a ring nozzle according to an embodiment. Although not shown in Figs. 15A and 15B, a substrate Wf is placed in the space inside the ring nozzle 604 (see Figs. 11-13 and 16). The configurations of Figs. 15A, 15B, and 16 can be applied to any of the configurations of the underwater plasma processing module 340 described above.

[0099] In the example of FIG. 15A , the nozzle openings 605A are positioned so as to face approximately in the circumferential direction of the ring nozzle 604 (the nozzle openings 605A are positioned so as to face at an angle closer to the circumferential direction than the radial direction of the ring nozzle 604). This creates a spiral flow of the processing liquid 650 on the surface of the substrate Wf, forming a liquid film on the surface of the substrate Wf and immersing the surface of the substrate Wf in the processing liquid 650. This allows the processing liquid to be supplied uniformly over the entire substrate surface. This configuration is particularly suitable when adding a chemical solution to the processing liquid 650, as it allows the chemical solution to be supplied uniformly over the entire substrate surface. In the example of FIG. 15B , the nozzle openings 605A are positioned so as to face in the radial direction of the ring nozzle 604. This allows the processing liquid 650 to be supplied toward the center of the substrate Wf, forming a liquid film of the processing liquid 650 on the surface of the substrate Wf and immersing the surface of the substrate Wf in the processing liquid 650. This configuration also allows the processing liquid to be supplied uniformly over the entire substrate surface. This configuration also simplifies the configuration of the ring nozzle 604. 15A and 15B, the processing liquid 650 can be supplied to the surface of the substrate Wf from obliquely above, as shown in Fig. 16. Note that the configurations shown in Fig. 15A, 15B, and 16 are examples of the ring nozzle 604, and other configurations may be adopted for the ring nozzle 604.

[0100] 17 is an explanatory diagram for explaining generation of active species (radicals) at the gas-liquid interface. As shown in the figure, plasma 550 generated in the gas phase comes into contact with the processing liquid 650, and electrons in the plasma are converted to H ２ O and / or H ２ O ２ By colliding with the active species OH ＊ The generated active species OH ＊ comes into contact with the surface of the substrate Wf, and the surface of the substrate is modified with OH groups.

[0101] When a pulsed DC power supply or an AC power supply is used and the stage 600 for the substrate Wf is set to the ground potential side, H ２ An electrolytic reaction of O occurs, and O ２ Gas is generated and O ２ Gas and H ２The gas (when H2 gas is added) is ionized by the plasma, and activated species O ＊ , H ＊ is generated, and the active species O ＊ , H ＊ By OH ＊ The generated active species OH ＊ comes into contact with the surface of the substrate Wf, and the surface of the substrate is modified with OH groups. ＊ Since the OH groups have a short life span, they are not consumed by the OH group modification of the substrate Wf. ＊ is inactivated and H ２ O ２ is generated. The generated H ２ O ２ collide with the electrons at the gas-liquid interface again, and OH ＊ Generate.

[0102] 18 is a flowchart showing the flow of the underwater plasma treatment according to one embodiment. The underwater plasma treatment is controlled by the control module 220.

[0103] In step S21, the substrate Wf is placed on the stage 600, and the pressure inside the chamber 341 is reduced to a predetermined pressure.

[0104] In step S22, plasma is generated in a dry environment by supplying Ar gas into the chamber 341. The substrate Wf to be subjected to the dry plasma treatment is preferably a dried substrate that has been subjected to a drying treatment in advance. However, the substrate may be a substrate that has been carried in a wet state (before being dried) from a previous process.

[0105] In step S23, the substrate Wf is subjected to dry plasma treatment using the plasma generated in step S22. This forms dangling bonds on the surface (bonding surface) of the substrate Wf (preliminary surface activation). At the same time, the dry plasma treatment increases surface roughness, thereby improving the adsorption of water molecules to the substrate surface. The dry plasma treatments in steps S22 and S23 are performed before the underwater plasma treatment in order to form dangling bonds on the substrate surface and / or strengthen the adsorption of water molecules. However, the dry plasma treatments in steps S22 and S23 may be omitted.

[0106] In step S24, the supply of the processing liquid 650 to the surface of the substrate Wf is started. The processing liquid 650 is ultrapure water or H ２ O ２ It can be an aqueous solution.

[0107] In step S25, a processing gas 540 is supplied into the chamber 341. Since the plasma has already been generated in step S22, the substrate Wf is subjected to an underwater plasma process in steps S24 and S25, and the substrate surface is activated and hydrophilized (surface activation and surface hydrophilization are performed in the same process).

[0108] In step S26, after a certain period of time, the generation of plasma is stopped and the supply of the processing gas 540 is stopped.

[0109] In step S27, a cleaning liquid is supplied to the surface of the substrate Wf to clean the surface of the substrate. The supply of the cleaning liquid can be performed by switching the liquid flowing through the supply path (ring nozzle 604) of the processing liquid 650 from the processing liquid 650 to the cleaning liquid. The cleaning liquid can be pure water (e.g., pure water containing bubbles).

[0110] In step S28, the supply of the cleaning liquid is stopped, and the substrate Wf is transported. Note that the substrate Wf may be dried before being transported. The drying process of the substrate Wf may include rotating the substrate Wf under atmospheric pressure or reduced pressure. The drying process of the substrate Wf may be performed in the chamber 341.

[0111] (Plasma Control) Fig. 19 is a cross-sectional view of an underwater plasma processing module that controls plasma based on the emission spectrum, and Fig. 20 is a flowchart showing the flow of plasma control based on the emission spectrum.

[0112] As shown in Fig. 19, when control based on the optical emission spectrum is performed in the underwater plasma treatment module 340, an optical fiber 552 inserted into the chamber 341 is connected to an optical emission spectrometer 551, and an optical signal detected by the optical fiber 552 is input to the optical emission spectrometer 551. Note that Fig. 19 shows a configuration in which the optical fiber 552 and the optical emission spectrometer 551 are added to the configuration of Fig. 11, but the optical fiber 552 and the optical emission spectrometer 551 can also be added to the configurations of Figs. 12 and 13 in the same way.

[0113] 20 , in step S31, the optical emission spectrometer 551 analyzes the optical signal detected by the optical fiber 552 to obtain an optical emission spectrum. This optical emission spectrum is data that changes depending on the dielectric wear (wear of the dielectric layer 504) of the plasma generator (plasma generating unit) 500 and the material / surface condition of the target substrate Wf.

[0114] In step S32, the control module 220 calculates the relative intensity (peak area) of the main active species, the electron temperature and the electron density in the plasma. Hereinafter, the relative intensity (peak area) is also referred to as the active species intensity. In this embodiment, the main active species is, for example, OH ＊ , H ＊ is.

[0115] In step S34, a database of correlations (influence indices) between each equipment parameter and the active species intensity, electron temperature, and electron density is referenced, and the adjustment values ​​of the equipment parameters are predicted by data analysis. The database is created in advance by machine learning or the like. For example, haze estimation or the like can be used to predict the adjustment values ​​of the equipment parameters.

[0116] The equipment parameters include, for example, the output / frequency of the plasma power supply, the distance from the plasma generator to the substrate bonding surface, the chamber pressure, and the gas flow rate / composition. Some of these equipment parameters may be omitted, or other equipment parameters may be added to these equipment parameters.

[0117] In step S33, the active species intensity, electron temperature, and electron density calculated in step S32 are compared with the recommended values ​​for the substrate surface treatment, and if the deviation between the calculated values ​​and the recommended values ​​exceeds a threshold, the process proceeds to step S35. If the deviation between the calculated values ​​and the recommended values ​​does not exceed the threshold, the process returns to step S31, and the process from step S31 is repeated.

[0118] In determining the deviation between the calculated value and the recommended value, if any one of the active species intensity, the electron temperature, and the electron density exceeds a threshold, it may be determined that the deviation between the calculated value and the recommended value exceeds the threshold. Alternatively, the active species intensity, the electron temperature, and the electron density may be treated as vectors, and the distance (deviation) between the vector of the calculated value and the vector of the recommended value may be calculated, and if the distance exceeds the threshold, it may be determined that the deviation between the calculated value and the recommended value exceeds the threshold.

[0119] In step S35, the apparatus parameters are automatically adjusted based on the adjustment values ​​of the apparatus parameters predicted in step S34, and the active species intensity, electron temperature, and electron density are corrected. Then, the process returns to step S31, and the process from step S31 is repeated.

[0120] Other Embodiments (1) While the above embodiment illustrates an example of bonding wafers, the above embodiment can be applied to bonding any type of substrates having bonding surfaces that include at least a portion of a dielectric surface. (2) While the above embodiment illustrates an example of bonding circular wafers, one or both of the substrates to be bonded may be polygonal (e.g., rectangular) or any other shape. (3) While the above embodiment illustrates an example in which the bonding surfaces of the bonded substrates Wf1 and Wf2 have the same pattern (the same pattern of the metal surface 13) (e.g., FIG. 1B), the bonding surfaces of the bonded substrates may have different patterns, as described in, for example, Non-Patent Document 1. For example, some or all of the metal surface area on one substrate may have different dimensions (area) from the corresponding metal surface area on the other substrate (see Fig. 1 in Non-Patent Document 1). (4) The above embodiment can also be applied to bonding power semiconductor-related substrates and forming transistors by substrate stacking (substrate bonding).

[0121] At least the following technical ideas can be grasped from the above embodiments. [1] According to one aspect, there is provided a substrate bonding method for bonding substrates each having a dielectric surface at least in a portion thereof, the method comprising the steps of: preparing a first substrate having a first bonding surface at least in a portion thereof including a dielectric surface; immersing at least the first bonding surface of the first substrate in a liquid; subjecting the first bonding surface of the first substrate, while the first bonding surface is immersed in the liquid, to an underwater plasma treatment; preparing a second substrate having a second bonding surface at least in a portion thereof including a dielectric surface; and bonding the first bonding surface of the first substrate, which has been subjected to the underwater plasma treatment, to the second bonding surface of the second substrate.

[0023] Examples of materials for the dielectric film (dielectric surface) include a silicon oxide film (SiO ２ ), silicon carbonitride (SiCN), silicon carbonate (SiCO), silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), aluminum gallium nitride (AlGaN), or any other dielectric material used in semiconductor manufacturing processes, panel manufacturing processes, etc. The second bonding surface of the second substrate may be subjected to an underwater plasma treatment before the bonding step, or may be subjected to a surface activation treatment other than the underwater plasma treatment (e.g., dry plasma treatment) and / or a hydrophilization treatment. Alternatively, the second bonding surface of the second substrate may not be subjected to a surface treatment (surface activation treatment, hydrophilization treatment) before the bonding step.

[0122] According to this embodiment, the surface modification treatment (surface activation treatment) and hydrophilization treatment of the substrate bonding surfaces can be performed in a single process (in a single chamber). Because the substrate bonding surfaces are plasma-treated in a liquid, particle adhesion or fixation to the substrate bonding surfaces during plasma treatment can be suppressed. Furthermore, because the substrate bonding surfaces are not exposed to the atmosphere after plasma activation and before hydrophilization treatment, particle adhesion or fixation to the substrate bonding surfaces in the atmosphere can be suppressed. Furthermore, because the surface modification treatment and hydrophilization treatment are performed in a single process (in a single chamber), the number of processing steps and the number of modules used for processing can be reduced. The reduced number of modules can reduce the equipment footprint. Furthermore, because the reduced number of modules can be installed, throughput can be improved by installing multiple modules capable of parallel processing. Furthermore, this embodiment can be expected to strengthen the adhesive strength of the substrates when bonding them together. In conventional methods, the substrate bonding surfaces are exposed to the atmosphere after plasma activation, which can expose the substrate bonding surfaces to atmospheric contamination and prevent the substrate bonding surfaces from being satisfactorily hydrophilized. On the other hand, according to this embodiment, the bonding surfaces of the substrates are covered with liquid water until hydrophilic groups (OH groups, etc.) are introduced by the hydrophilization treatment, so that the bonding surfaces of the substrates can be made hydrophilic well.

[0123] [2] According to one embodiment, the underwater plasma treatment is carried out under reduced pressure.

[0124] According to this aspect, by performing underwater plasma processing under reduced pressure, the processing gas can be easily excited, and plasma can be easily generated.

[0125] [3] According to one embodiment, the method further includes a step of drying the first bonding surface of the first substrate after the underwater plasma treatment.

[0126] According to this aspect, the substrates can be bonded together while the bonding surfaces of the substrates are dry, and the substrates can be bonded more satisfactorily.

[0127] [4] According to one embodiment, the drying step includes rotating the first substrate under atmospheric pressure or reduced pressure.

[0128] According to this aspect, the substrate can be dried efficiently by rotating the substrate.

[0129] [5] According to one aspect, the step of drying the first bonding surface is performed in the chamber in which the underwater plasma treatment is performed.

[0130] According to this aspect, the underwater plasma treatment and drying are carried out in the same chamber, so that the configuration of the apparatus can be simplified.

[0131] [6] According to one embodiment, the step of preparing the first substrate includes the steps of polishing the first substrate before performing the underwater plasma treatment, and cleaning the polished first substrate.

[0132] According to this embodiment, it is possible to use wet processes from at least the polishing step (e.g., CMP) to the step of making the bonding surfaces hydrophilic, which allows the substrate surfaces before bonding to be continuously treated in a wet state, thereby suppressing the adhesion or fixation of particles to the substrate bonding surfaces.

[0133] [7] According to one embodiment, the method further includes a first transfer step of transferring the first substrate between the polishing step and the cleaning step, and a second transfer step of transferring the first substrate between the cleaning step and the underwater plasma treatment step, wherein the first transfer step and the second transfer step are performed in a state where at least the first bonding surface of the first substrate is kept wet by an anti-dry module.

[0134] According to this aspect, by carrying out a process of keeping the substrate wet even during transportation between the polishing process, cleaning process, and underwater plasma treatment process, adhesion of particles to the substrate bonding surface can be further suppressed.

[0135] [8] According to one embodiment, in the first transfer step and the second transfer step, the anti-drying module supplies a liquid to the first bonding surface of the first substrate during transfer, or humidifies the air around the first substrate. The air may be humidified by supplying humidified air around the substrate, or by supplying a liquid (e.g., pure water) to the air around the substrate. Any other configuration or method for maintaining the substrate in a wet state may be employed as the anti-drying module. It is preferable that the liquid supplied by the anti-drying module be degassed.

[0136] According to this aspect, the bonding surfaces of the substrates can be kept wet during transportation in a simple manner. Furthermore, supplying liquid to the substrates during transportation provides the liquid with fluidity on the substrate bonding surfaces, which has the effect of suppressing particle adhesion.

[0137] [9] According to one embodiment, the liquid supplied by the anti-drying module is degassed.

[0138] According to this aspect, since the liquid in contact with the substrate is degassed, oxidation of the substrate can be suppressed.

[0139]

[10] According to one embodiment, the polishing step is performed by a polishing module, the cleaning step is performed by a cleaning module, the underwater plasma treatment step is performed by an underwater plasma treatment module, the bonding step is performed by a bonding module, the cleaning module is connected to the bonding module via the underwater plasma treatment module, and the first substrate is cleaned by the cleaning module and then transported to the bonding module via the underwater plasma treatment module.

[0140] According to this aspect, by connecting the cleaning module after the polishing module and the bonding module via the underwater plasma treatment module, it is possible to control the airflow between the cleaning module and the bonding module and to prevent particles and chemical atmosphere from flowing into the bonding apparatus. Furthermore, by reducing the pressure in the underwater plasma treatment module (underwater plasma treatment apparatus), it is possible to more effectively prevent particles and chemical atmosphere from flowing into the bonding apparatus.

[0141]

[11] According to one embodiment, the method further includes a step of performing an underwater plasma treatment on the second bonding surface of the second substrate before the bonding step.

[0142] According to this embodiment, the second substrate can also achieve the same effects (such as suppression of particle adhesion) as those described above for the first substrate. Furthermore, since each substrate to be bonded is subjected to underwater plasma treatment, the bonding of the substrates is improved.

[0143]

[12] According to one embodiment, the underwater plasma treatment is performed on the second bonding surface of the second substrate while the underwater plasma treatment is being performed on the first bonding surface of the first substrate, even if the start and end timings of the treatments on both substrates are somewhat different.

[0144] According to this embodiment, the bonding surfaces of both substrates to be bonded can be processed at the same time, which is more suitable for bonding. In other words, since both substrates are not left unattended before bonding, it is possible to suppress or prevent contamination of the bonding surfaces of both substrates.

[0145]

[13] According to one embodiment, the dielectric surfaces formed on the first bonding surface of the first substrate and the second bonding surface of the second substrate are made of SiO ２ , SiCN, SiCO, SiC, GaN, AlN, and AlGaN.

[0146] According to this aspect, the above-mentioned effects can be exerted on the dielectric surface included in the bonding surface of the substrate used in the semiconductor manufacturing process.

[0147]

[14] According to one embodiment, the first bonding surface of the first substrate and the second bonding surface of the second substrate further include a metal surface region.

[0148] According to this aspect, the above-described advantageous effects can be achieved in hybrid bonding for joining substrates including a dielectric surface and a metal surface.

[0149]

[15] According to one aspect, after the first bonding surface of the first substrate is bonded to the second bonding surface of the second substrate, an annealing treatment is performed.

[0150] According to this embodiment, the annealing process removes moisture from between the substrate bonding surfaces, thereby achieving good bonding of the substrates. Furthermore, if the metal surfaces are concave due to polishing or other processes, the annealing process thermally expands the metal, allowing the metal surfaces to be bonded together.

[0151]

[16] According to one embodiment, the method further comprises a step of degassing the liquid used in the underwater plasma treatment step before the underwater plasma treatment step.

[0152] According to this embodiment, in hybrid bonding, the concentration of dissolved oxygen in the liquid can be reduced, and oxidation of the metal surface can be suppressed.

[0153]

[17] According to one embodiment, the temperature of the liquid used in the underwater plasma treatment step is higher than 0°C and lower than 100°C.

[0154] According to this embodiment, by setting the temperature within the above range suitable for underwater plasma treatment under atmospheric pressure or reduced pressure, surface modification and hydrophilization by underwater plasma treatment can be carried out satisfactorily.

[0155]

[18] According to one embodiment, the method further includes adding a chemical solution to the liquid before, during, or after the underwater plasma treatment.

[0156] According to this aspect, by adding an appropriate chemical to the liquid in which the substrate bonding surfaces are immersed, the bonding strength of the substrates can be improved.

[0157]

[19] According to one aspect, after the underwater plasma treatment step, the chemical solution is supplied to the first bonding surface of the first substrate while the first substrate is being rotated under atmospheric pressure or reduced pressure.

[0158] According to this embodiment, the chemical solution can be supplied uniformly to the substrate bonding surfaces.

[0159]

[20] According to one embodiment, the chemical solution contains at least one of F (fluorine) or N (nitrogen).

[0160] According to this embodiment, hydrogen bonding between the substrates when they are bonded together can be strengthened, thereby improving the bonding strength.

[0161]

[21] According to one aspect, in the underwater plasma treatment, a gas having a molecular structure containing F (fluorine) or N (nitrogen) is supplied into a chamber in which the plasma treatment is performed.

[0162] According to this embodiment, hydrogen bonding between the substrates when they are bonded together can be strengthened, and the bonding strength between the substrates can be improved.

[0163]

[22] According to one embodiment, the method further includes a step of plasma treating the first bonding surface of the first substrate with an inert gas before immersing the first bonding surface in the liquid.

[0164] According to this embodiment, by performing dry plasma treatment before performing underwater plasma treatment, the formation of dangling bonds at the substrate bonding surface and the adsorption of water molecules can be further improved, thereby improving the surface modification and hydrophilization of the substrate bonding surface.

[0165]

[23] According to one embodiment, an underwater plasma processing module that performs the underwater plasma processing is provided with a measuring device that optically measures the intensity (density) of active species generated by the plasma, the electron temperature, which is the temperature and density of electrons in the plasma, and the electron density, and the underwater plasma processing module is adjusted to optimize the intensity, electron temperature, and electron density of the active species based on the intensity, electron temperature, and electron density measured by the measuring device, by adjusting the output and frequency of a power source for plasma generation, the distance between a plasma generator and the first bonding surface of the first substrate, the flow rate and composition ratio of the gas supplied to the underwater plasma processing module, and the pressure within the underwater plasma processing module.

[0166] According to this embodiment, each equipment parameter of the underwater plasma processing module is adjusted to optimize the intensity, electron temperature, and electron density of activated species generated by the plasma based on measured values ​​thereof, thereby enabling highly accurate underwater plasma processing.

[0167]

[24] According to one embodiment, there is provided a substrate bonding system for bonding substrates together that include a dielectric surface on at least a portion of their bonding surfaces, the substrate bonding system comprising: an underwater plasma treatment module that performs underwater plasma treatment on at least a first bonding surface of a first substrate, the first bonding surface having a first bonding surface that includes a dielectric surface at least in a state where the first bonding surface is immersed in a liquid; and a bonding module that bonds the first bonding surface of the first substrate that has been subjected to the underwater plasma treatment to a second bonding surface of a second substrate, the second bonding surface having a second bonding surface that includes a dielectric surface at least in a portion thereof.

[0168] According to this embodiment, the same effects as those described in [1] above can be achieved.

[0169]

[25] According to one embodiment, the bonding system further includes a polishing module that polishes the first substrate, and a cleaning module that cleans the polished first substrate, wherein the cleaning module is connected to the bonding module via the underwater plasma treatment module.

[0170] According to this aspect, by connecting the cleaning module after the polishing module and the bonding module via the underwater plasma treatment module, it is possible to control the airflow between the cleaning module and the bonding module and to prevent particles and chemical atmosphere from flowing into the bonding apparatus. Furthermore, by reducing the pressure in the underwater plasma treatment module (underwater plasma treatment apparatus), it is possible to more effectively prevent particles and chemical atmosphere from flowing into the bonding apparatus.

[0171]

[26] According to one embodiment, the apparatus further includes: a first transport path for transporting the first substrate between the polishing module and the cleaning module; a second transport path for transporting the first substrate between the cleaning module and the underwater plasma treatment module; a first anti-drying module provided on the first transport path for keeping at least the first bonding surface of the first substrate wet; and a second anti-drying module provided on the second transport path for keeping at least the first bonding surface of the first substrate wet.

[0172] According to this aspect, by carrying out a process of keeping the substrate wet even during transportation between the polishing process, cleaning process, and underwater plasma treatment process, adhesion of particles to the substrate bonding surface can be further suppressed.

[0173]

[27] According to one embodiment, the underwater plasma treatment module comprises: a stage on which the first substrate is placed; a plasma generator facing the stage; and a ring nozzle arranged on the stage surrounding the first substrate, the ring nozzle having a height higher than the first substrate, and having a plurality of nozzle openings on its inner surface for ejecting the liquid.

[0174] According to this aspect, by supplying the liquid to the substrate bonding surfaces from the periphery of the substrates using the ring nozzle, the liquid can be dispersed uniformly over the substrate bonding surfaces.

[0175]

[28] According to one aspect, the underwater plasma processing module further performs underwater plasma processing on the second bonding surface of the second substrate while the second bonding surface is immersed in a liquid.

[0176] According to this embodiment, the second substrate can also achieve the same effects (such as suppression of particle adhesion) as those described above for the first substrate. Furthermore, since each substrate to be bonded is subjected to underwater plasma treatment, the bonding of the substrates is improved.

[0177]

[29] According to one embodiment, the method further includes a second underwater plasma processing module that performs underwater plasma processing on the second bonding surface of the second substrate while the second bonding surface is immersed in a liquid.

[0178] This configuration allows the first and second substrates to be simultaneously subjected to underwater plasma treatment in multiple underwater plasma treatment modules, making it more suitable for bonding. In other words, the first and second substrates are not left unattended before bonding, which reduces or prevents contamination of the bonding surfaces of the first and second substrates. Furthermore, there is no need to provide a configuration and / or procedure for keeping the substrates wet while waiting for underwater plasma treatment.

[0179] Although embodiments of the present invention have been described above based on several examples, the above-described embodiments of the invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified and improved without departing from its spirit, and of course, equivalents thereof are included in the present invention. Furthermore, any combination or omission of the components described in the claims and specification is possible to the extent that at least part of the above-described problems can be solved or at least part of the effects can be achieved. This application claims priority to Japanese Patent Application No. 2024-060537, filed April 4, 2024. The entire disclosure of Japanese Patent Application No. 2024-060537, filed April 4, 2024, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety. The entire disclosure of Japanese Patent Application No. 2019-186288 (Patent Document 1), including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety. The entire disclosure of Fumihiro Inoue et al., “Area-Selective Electroless Deposition of Cu for Hybrid Bonding,” IEEE ELECTRON DEVICE LETTERS, VOL. 42, NO. 12, pp. 1826-1829, DECEMBER 2021 (Non-Patent Document 1) is incorporated herein by reference.

[0180] REFERENCE SIGNS LIST 11 Substrate body 12 Dielectric film (dielectric surface) 13 Metal film (metal surface) 14 Thin film (barrier layer, seed layer, etc.) 100 Substrate bonding system 200 Polishing apparatus 201 Load port 202 EFFEM 203 Transfer robot (loader) 204, 205 Linear transporter 206 Polishing module 207 Swing transporter 208 Cleaning module 210, 211 Transfer robot 300 Underwater plasma processing apparatus 310 Loading section 320 Unloading section 330 Processing section 311, 321 Stage 312, 322 Traveling mechanism 340 Underwater plasma processing module 341 Chamber 342 Gas inlet 343 Gas outlet 344 Exhaust port 345, 346 Fluid line 347 Pump 348 Circulation line 349 Pump 350, 351 High frequency power supply 400 Bonding device 410 Bonding module 420 Transfer robot 450 Transfer line 500, 500A Plasma generator 501 Dielectric part 502 Conductive part (waveguide) 503 Antenna (electrode) 504 Dielectric layer 510, 510A Gas introduction path 511 Flow path 512 Through hole (gas inlet) 540 Processing gas 550 Plasma 551 Optical emission spectrometer 552 Optical fiber 600 Stage 601 Discharge hole 602 Cylindrical part 603 Flow path 604 Ring nozzle 605 Flow path 605A Nozzle opening 650 Processing liquid

Claims

1. A method for bonding substrates, at least a portion of which includes a dielectric surface, comprising the steps of: preparing a first substrate having a first bonding surface, at least a portion of which includes a dielectric surface; immersing at least the first bonding surface of the first substrate in a liquid; subjecting the first bonding surface of the first substrate, while the first bonding surface is immersed in the liquid, to an underwater plasma treatment; preparing a second substrate having a second bonding surface, at least a portion of which includes a dielectric surface; and bonding the first bonding surface of the first substrate, which has been subjected to the underwater plasma treatment, to the second bonding surface of the second substrate.

2. The method for bonding substrates according to claim 1, wherein the underwater plasma treatment is carried out under reduced pressure.

3. The method for bonding substrates according to claim 1, further comprising the step of drying the first bonding surface of the first substrate after the underwater plasma treatment.

4. A substrate bonding method according to claim 3, wherein the drying step includes rotating the first substrate under atmospheric pressure or reduced pressure.

5. A substrate bonding method according to claim 1, wherein the step of drying the first bonding surface is carried out in the chamber in which the underwater plasma treatment is carried out.

6. A substrate bonding method according to claim 1, wherein the step of preparing the first substrate includes the steps of polishing the first substrate before performing the underwater plasma treatment, and cleaning the polished first substrate.

7. A substrate bonding method according to claim 6, further comprising: a first transport step of transporting the first substrate between the polishing step and the cleaning step; and a second transport step of transporting the first substrate between the cleaning step and the underwater plasma treatment step, wherein the first transport step and the second transport step are carried out in a state where at least the first bonding surface of the first substrate is kept wet by an anti-dry module.

8. A substrate bonding method according to claim 7, wherein in the first transfer step and the second transfer step, the anti-drying module supplies a liquid to the first bonding surface of the first substrate during transfer, or humidifies the air around the first substrate.

9. The method for bonding substrates according to claim 8, wherein the liquid supplied by the anti-drying module is degassed.

10. A substrate bonding method according to claim 6, wherein the polishing step is performed by a polishing module, the cleaning step is performed by a cleaning module, the underwater plasma treatment step is performed by an underwater plasma treatment module, the bonding step is performed by a bonding module, the cleaning module is connected to the bonding module via the underwater plasma treatment module, and the first substrate is cleaned by the cleaning module and then transported to the bonding module via the underwater plasma treatment module.

11. The method for bonding substrates according to claim 1, further comprising the step of subjecting the second bonding surface of the second substrate to underwater plasma treatment before the bonding step.

12. A substrate bonding method according to claim 11, wherein the step of performing the underwater plasma treatment on the second bonding surface of the second substrate is performed while the underwater plasma treatment is being performed on the first bonding surface of the first substrate.

13. The substrate bonding method according to claim 1, wherein the dielectric surfaces formed on the first bonding surface of the first substrate and the second bonding surface of the second substrate are made of SiO ２ , SiCN, SiCO, SiC, GaN, AlN, AlGaN.

14. The method for bonding substrates according to claim 1, wherein the first bonding surface of the first substrate and the second bonding surface of the second substrate further include metal surface regions.

15. A substrate bonding method according to claim 1, wherein after the first bonding surface of the first substrate is bonded to the second bonding surface of the second substrate, an annealing treatment is performed.

16. The method for bonding substrates according to claim 14, further comprising a step of degassing the liquid used in the underwater plasma treatment step before the underwater plasma treatment step.

17. A substrate bonding method according to claim 1, wherein the temperature of the liquid used in the underwater plasma treatment step is higher than 0°C and lower than 100°C.

18. The method for bonding substrates according to claim 1, further comprising the step of adding a chemical liquid to the liquid before, during, or after the underwater plasma treatment.

19. A substrate bonding method according to claim 18, wherein, after the underwater plasma treatment step, the chemical solution is supplied to the first bonding surface of the first substrate while the first substrate is rotated under atmospheric pressure or reduced pressure.

20. A substrate bonding method according to claim 18 or 19, wherein the chemical solution contains at least one of F (fluorine) and N (nitrogen).

21. A substrate bonding method according to claim 1, wherein in the underwater plasma treatment, a gas having a molecular structure containing F (fluorine) or N (nitrogen) is supplied into a chamber in which the plasma treatment is carried out.

22. The method for bonding substrates according to claim 1, further comprising the step of plasma treating the first bonding surface of the first substrate with an inert gas before immersing the first bonding surface in the liquid.

23. A substrate bonding method according to claim 1, comprising providing an underwater plasma processing module in which the underwater plasma processing is carried out with a measuring device that optically measures the intensity (density) of active species generated by the plasma, the electron temperature, which is the temperature and density of electrons in the plasma, and the electron density, and adjusting, in the underwater plasma processing module, the output and frequency of the power source for generating plasma, the distance between a plasma generator and the first bonding surface of the first substrate, the flow rate and composition ratio of the gas supplied to the underwater plasma processing module, and the pressure within the underwater plasma processing module, so as to optimize the intensity, electron temperature, and electron density of the active species based on the intensity, electron temperature, and electron density measured by the measuring device.

24. A substrate bonding system for bonding substrates each having a dielectric surface on at least a portion of their bonding surfaces, comprising: an underwater plasma treatment module that performs underwater plasma treatment on at least a first bonding surface of a first substrate having a first bonding surface at least a portion of which includes a dielectric surface while the first bonding surface is immersed in a liquid; and a bonding module that bonds the first bonding surface of the first substrate that has been subjected to the underwater plasma treatment to a second bonding surface of a second substrate having a second bonding surface at least a portion of which includes a dielectric surface.

25. A substrate bonding system according to claim 24, further comprising: a polishing module for polishing the first substrate; and a cleaning module for cleaning the polished first substrate, wherein the cleaning module is connected to the bonding module via the underwater plasma processing module.

26. A substrate bonding system according to claim 25, further comprising: a first transport path for transporting the first substrate between the polishing module and the cleaning module; a second transport path for transporting the first substrate between the cleaning module and the underwater plasma treatment module; a first anti-drying module provided on the first transport path for keeping at least the first bonding surface of the first substrate wet; and a second anti-drying module provided on the second transport path for keeping at least the first bonding surface of the first substrate wet.

27. A substrate bonding system according to claim 24, wherein the underwater plasma processing module comprises: a stage on which the first substrate is placed; a plasma generator facing the stage; and a ring nozzle arranged on the stage surrounding the first substrate, the ring nozzle having a height greater than that of the first substrate, and having a plurality of nozzle openings on its inner surface for discharging the liquid.

28. A substrate bonding system according to any one of claims 24 to 27, wherein the underwater plasma processing module further performs underwater plasma processing on the second bonding surface of the second substrate while the second bonding surface is immersed in a liquid.

29. A substrate bonding system according to any one of claims 24 to 27, further comprising a second underwater plasma treatment module that performs underwater plasma treatment on the second bonding surface of the second substrate while the second bonding surface is immersed in a liquid.

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