Coating unit and substrate bonding device comprising same

Abstract

This coating unit comprises: a chuck that, while holding a substrate having a bonding surface which is to be bonded to another substrate, rotates about an axis which is orthogonal to the main surface of the substrate and which passes through the center of the main surface; and a filling liquid nozzle that, by ejecting a filling liquid which changes to a solid or semisolid filler toward the bonding surface of substrate held by the chuck, supplies the filling liquid only to an outer peripheral part of the bonding surface of the substrate.

Description

Coating unit and substrate bonding device equipped with same

[0001] The present invention relates to a coating unit for coating one or both of two substrates with a filler liquid before they are bonded, and to a substrate bonding apparatus including the same. The substrates include, for example, semiconductor wafers, substrates for FPDs (Flat Panel Displays) such as liquid crystal displays and organic electroluminescence (EL) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells.

[0002] Patent Document 1 discloses an edge condition checking device capable of determining whether or not there is an internal defect in a protective member formed on the outer peripheral edge of a substrate. Paragraph 0089 of Patent Document 1 states, "A coating liquid for the protective member is filled into the space between the bevel portion of single substrate w1 and the bevel portion of single substrate w2. The filled coating liquid hardens to form protective member w4."

[0003] JP 2023-43003 A

[0004] In the edge condition checking device described in Patent Document 1, after two substrates are bonded together, a coating liquid is filled into the space between the outer peripheries of the two substrates. The width of the space between the outer peripheries of the bonded two substrates (the length of the space in the thickness direction of the two substrates) decreases as the bottom of the space approaches. Therefore, it is difficult for the coating liquid to reach the bottom of the space.

[0005] At least one embodiment of the present invention provides an application unit that can place a filling liquid at a deeper position in the space between the outer peripheries of two bonded substrates, and a substrate bonding apparatus equipped with the application unit.

[0006] One embodiment of the present invention provides a coating unit including: a chuck that holds a substrate having a bonding surface to be bonded to another substrate and rotates about an axis that is perpendicular to the main surface of the substrate and passes through the center of the main surface; and a filling liquid nozzle that supplies filling liquid only to the outer periphery of the bonding surface of the substrate held by the chuck by ejecting filling liquid that changes into a solid or semi-solid filler toward the bonding surface of the substrate held by the chuck. The substrate includes a front surface and a back surface that are two planes parallel to each other. The main surface of the substrate may be either the front surface or the back surface of the substrate. One of the front surface and the back surface of the substrate is a bonding surface to be bonded to another substrate, and the other of the front surface and the back surface of the substrate is a non-bonding surface that is not bonded to another substrate.

[0007] In the above embodiment, at least one of the following features may be added to the application unit.

[0008] The joining surface of the substrate includes a flat portion that is joined to another substrate, and the outer periphery that is recessed from the outer periphery of the flat portion toward the non-joining surface of the substrate opposite the joining surface.

[0009] The filling liquid nozzle is a droplet nozzle that supplies the filling liquid only to the outer periphery of the joining surface of the substrate by spraying multiple droplets of the filling liquid toward the outer periphery of the joining surface of the substrate held by the chuck.

[0010] The droplet nozzle includes a large-diameter nozzle that sprays multiple droplets of the filling liquid from a spray port toward the outer periphery of the bonding surface of the substrate held by the chuck, and a small-diameter nozzle that sprays multiple droplets of the filling liquid from a spray port having an area smaller than the spray port of the large-diameter nozzle toward the outer periphery of the bonding surface of the substrate held by the chuck.

[0011] The coating unit further includes a position detector that detects the position of the outer periphery of the substrate held by the chuck, and a nozzle actuator that moves the filling liquid nozzle in accordance with the position of the outer periphery detected by the position detector.

[0012] The coating unit further includes a control device that performs at least one of the following, in accordance with the position of the outer periphery of another substrate detected by the position detector: position control that causes the nozzle actuator to move the filling liquid nozzle; and flow rate control that changes the amount of filling liquid sprayed from the filling liquid nozzle per unit time in accordance with the position of the outer periphery detected by the position detector while causing the position detector to detect the position of the outer periphery of the substrate held by the chuck.

[0013] Another embodiment of the present invention provides a substrate bonding device including: an application unit that applies a filling liquid that changes into a solid or semi-solid filler to a substrate; and a bonding unit that bonds two substrates, at least one of which has the filling liquid applied thereto, wherein the application unit includes a chuck that holds a substrate having a bonding surface to be bonded to another substrate and rotates about an axis that is perpendicular to a main surface of the substrate and passes through the center of the main surface; and a filling liquid nozzle that supplies the filling liquid only to the outer periphery of the bonding surface of the substrate by discharging the filling liquid toward the bonding surface of the substrate held by the chuck.

[0014] 1 is a schematic diagram showing an example of the appearance of two substrates before and after bonding; FIG. 2 is a schematic diagram showing an example of cross sections of two substrates before and after bonding; FIG. 3 is a schematic diagram showing an example of cross sections of substrates before and after supplying a filler liquid to the bonding surfaces of the substrates; FIG. 4 is a schematic diagram showing an example of cross sections of two bonded substrates before and after thinning the two substrates; FIG. 5 is a process diagram for explaining a substrate bonding method according to an embodiment of the present invention; FIG. 6 is a schematic plan view of a substrate bonding apparatus according to an embodiment of the present invention; FIG. 7 is a schematic diagram showing the interior of a pre-activation aligner viewed horizontally; FIG. 8 is a schematic diagram showing the interior of a pre-activation aligner viewed from directly above; FIG. 9 is a schematic diagram showing the interior of an activation unit viewed horizontally; FIG. 10 is a schematic diagram showing the interior of an activation unit viewed from directly above; FIG. 11 is a schematic diagram showing the interior of a pre-bonding cleaning unit viewed horizontally; FIG. 12 is a schematic diagram showing the interior of a pre-bonding cleaning unit viewed from directly above; FIG. 13 is a schematic diagram showing the interior of a coating unit viewed horizontally; FIG. 14 is a schematic diagram of a filling liquid nozzle; FIG. 15 is a schematic diagram showing the interior of a bonding unit viewed horizontally; FIG. 16 is a schematic diagram showing the interior of a bonding unit viewed horizontally; FIG. 17 is a schematic diagram showing the interior of a grinding unit viewed horizontally; FIG. 18 is a schematic diagram showing the interior of a grinding unit viewed from directly above. FIG. 1 is a block diagram showing the electrical configuration of a substrate bonding apparatus. FIG. 2 is a schematic cross-sectional view of the outer periphery of a substrate. FIG. 3 is a schematic horizontal view of the inside of a coating unit. FIG. 4 is a schematic cross-sectional view showing a state in which a filler liquid is being supplied to the outer periphery of the bonding surface of a substrate. FIG. 5 is a schematic cross-sectional view showing a state in which a void in a filler on a substrate is being detected by a void detector. FIG. 6 is a schematic cross-sectional view showing a state in which a void between two bonded substrates is being detected by a void detector. FIG. 7 is a schematic plan view of a substrate showing a device region and a non-device region.

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] In the following description, a bonded substrate W refers to two bonded substrates W, a pre-bonded substrate W refers to one substrate W before bonding, and a bonded substrate W refers to one substrate W after bonding. Bonding is synonymous with bonding.

[0017] The first substrate W1 refers to a pre-bonded substrate W. The second substrate W2 refers to another pre-bonded substrate W. The bonded first substrate W1 and second substrate W2 refer to a bonded substrate W. Two bonded substrates W also refer to a bonded substrate W. When it does not matter whether it is a bonded substrate W, a pre-bonded substrate W, or a bonded substrate W, it is simply referred to as a substrate W.

[0018] Fig. 1A is a schematic diagram showing an example of the appearance of two substrates W before and after bonding. Fig. 1B is a schematic diagram showing an example of the cross section of two substrates W before and after bonding. Fig. 1C is a schematic diagram showing an example of the cross section of a substrate W before and after supplying a filling liquid FL to a bonding surface WA of the substrate W. Fig. 1D is a schematic diagram showing an example of the cross section of two bonded substrates W before and after thinning the two substrates W.

[0019] As shown in FIG. 1A , the first substrate W1 and the second substrate W2 are flat, circular plates with the same diameter. The diameters of the first substrate W1 and the second substrate W2 may be 300 mm or other diameters. The thermal expansion coefficient of the first substrate W1 may be the same as or different from the thermal expansion coefficient of the second substrate W2. The first substrate W1 includes a circular substrate WD1, and the second substrate W2 includes a circular substrate WD2. The substrate WD1 and the substrate WD2 are made of a semiconductor such as single crystal silicon. The substrate WD1 and the substrate WD2 may also be made of a material other than a semiconductor.

[0020] Both the substrate WD1 and the substrate WD2 include a circular front surface and a back surface that are parallel to each other, and an annular end surface that connects the outer edges of the front surface and the back surface. The front surface and the back surface of the substrate WD1 are flat surfaces that are parallel to each other. The front surface and the back surface of the substrate WD2 are similar. The front surfaces of the substrate WD1 and the substrate WD2 are device formation surfaces on which devices such as transistors are formed. The back surfaces of the substrate WD1 and the substrate WD2 are non-device formation surfaces on which devices are not formed. Both the front surface and the back surface of the substrate WD1 or the substrate WD2 may be device formation surfaces.

[0021] The outer periphery of the substrate WD1 forms a V-shaped notch that opens at the end face of the substrate WD1 when the substrate WD1 is viewed in a direction perpendicular to the surface of the substrate WD1. The outer periphery of the substrate WD1 may form an orientation flat (so-called orientation flat) instead of a notch. The notch and orientation flat indicate the crystal orientation of the substrate WD1 or the substrate WD2. The first substrate W1 is positioned in the circumferential direction of the first substrate W1 based on the notch or orientation flat of the first substrate W1. The same applies to the second substrate W2.

[0022] As shown in FIG. 1B , the first substrate W1 includes a device layer WC1 covering the surface of the substrate WD1 and a bonding layer WB1 covering the surface of the device layer WC1. The second substrate W2 includes a device layer WC2 covering the surface of the substrate WD2 and a bonding layer WB2 covering the surface of the device layer WC2. Devices such as transistors are disposed in the device layers WC1 and WC2. The devices are covered by the bonding layers WB1 and WB2. The bonding layers WB1 and WB2 are transparent or semi-transparent insulating layers. The bonding layers WB1 and WB2 may be silicon oxide films or thin films made of a material other than silicon oxide. In the former case, the bonding layers WB1 and WB2 may be silicon oxide films made using TEOS (tetraethoxysilane).

[0023] The surface of the bonding layer WB1 of the first substrate W1 is the bonding surface WA1 of the first substrate W1. The surface of the bonding layer WB2 of the second substrate W2 is the bonding surface WA2 of the second substrate W2. The first substrate W1 and the second substrate W2 are bonded so that the bonding surface WA1 of the first substrate W1 faces the bonding surface WA2 of the second substrate W2. The surface of the first substrate W1 is the bonding surface WA1 that comes into contact with the atmosphere in the space in which the first substrate W1 is placed. The surface of the second substrate W2 is the bonding surface WA2 that comes into contact with the atmosphere in the space in which the second substrate W2 is placed.

[0024] 2 is a process diagram illustrating a substrate bonding method according to one embodiment of the present invention. When bonding a first substrate W1 and a second substrate W2, an activation step (step S1 in FIG. 2 ) is performed to activate the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2, followed by a cleaning step (step S2 in FIG. 2 ) to clean and dry the two activated substrates W. This is followed by an application step (step S3 in FIG. 2 ) to apply a filler liquid FL to at least one of the first substrate W1 and the second substrate W2. FIG. 1C shows an example in which the filler liquid FL is applied to the outer periphery of the bonding surface WA2 of the second substrate W2 before it is bonded to the first substrate W1.

[0025] After the application of the filling liquid FL, an inversion process (step S4 in FIG. 2 ) is performed to invert one of the first substrate W1 and the second substrate W2. This is followed by an alignment confirmation process (step S5 in FIG. 2 ) to confirm the alignment, which indicates the relative position and angle of the first substrate W1 and the second substrate W2. This is followed by an alignment adjustment process (step S6 in FIG. 2 ) to adjust the alignment of the first substrate W1 and the second substrate W2 based on the confirmed alignment. This is followed by a substrate contact process (step S7 in FIG. 2 ) to bond the first substrate W1 and the second substrate W2 by bringing the aligned first substrate W1 and the second substrate W2 into contact with each other. This is followed by an inspection process (step S8 in FIG. 2 ) to inspect the bonding accuracy of the first substrate W1 and the second substrate W2, i.e., the amount of misalignment between the two bonded substrates W and the amount of misalignment between the two bonded substrates W (the angle around the center of the substrate W).

[0026] The activation step may be a plasma treatment in which plasma such as oxygen plasma is applied to the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2. In this case, moisture in the air or moisture supplied to the substrate W during the cleaning step comes into contact with the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2 that have been irradiated with the plasma, forming hydrophilic groups such as hydroxyl groups (OH groups) on the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2. The plasma treatment is an example of surface modification that modifies the surface of the substrate W. The activation step may also be a wet treatment in which a hydrophilizing liquid that forms hydrophilic groups is supplied to the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2.

[0027] The substrate contacting step may be a step of directly bonding two substrates W in the atmosphere at room temperature (e.g., 20 to 30°C). The substrate contacting step may be a step of performing face-to-face bonding in which the two substrates W are bonded together so that their surfaces face each other. In this case, the surfaces of the two substrates W correspond to the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2. The substrate contacting step may be a step of bonding two substrates W together without pressing one of the two substrates W against the other of the two substrates W, or by pressing one of the two substrates W against the other of the two substrates W with a pressure that does not damage devices formed on the two substrates W.

[0028] 1B shows a cross section of the first substrate W1 and the second substrate W2 cut along a plane perpendicular to the first substrate W1 and the second substrate W2. The ratio of the thickness of the device layer WC1 and the device layer WC2 to the thickness of the bonding layer WB1 and the bonding layer WB2 shown in FIG. 1B is not necessarily the same as the actual ratio. FIG. 1B shows an example in which hydroxyl groups, which are an example of hydrophilic groups, are formed on the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2 before bonding. In this example, oxygen atoms (O) in the hydroxyl groups are bonded to silicon atoms (Si) in the bonding layers WB1 and WB2.

[0029] Before bonding, the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2 are terminated with multiple hydroxyl groups. When the bonding surface WA1 of the first substrate W1 and the bonding surface WA2 of the second substrate W2 are brought into contact, the first substrate W1 and the second substrate W2 are bonded together due to the intermolecular force acting between the two hydroxyl groups. In some cases, water molecules are released from the two hydroxyl groups, and silicon atoms in the bonding layer WB1 of the first substrate W1 and silicon atoms in the bonding layer WB2 of the second substrate W2 are bonded together via oxygen atoms. In this manner, the first substrate W1 and the second substrate W2 are bonded together.

[0030] After the first substrate W1 and the second substrate W2 are bonded, as shown in Fig. 1D , a grinding process (step S9 in Fig. 2 ) is performed to thin the bonded first substrate W1 and second substrate W2, i.e., the bonded substrate W, by grinding one of the bonded first substrate W1 and second substrate W2, and a cleaning process (step S10 in Fig. 2 ) is performed to clean and dry the thinned bonded substrate W. Fig. 1D shows an example in which the thickness of the bonded substrate W is reduced by grinding the first substrate W1. Instead of reducing the thickness of the first substrate W1, the thickness of the second substrate W2 may be reduced.

[0031] The inspection process (step S8 in FIG. 2 ) may be performed after the grinding process (step S9 in FIG. 2 ) rather than before, or may be performed both before and after the grinding process. In the latter case, the bonding accuracy before and after the grinding process may be compared. A pass / fail judgment may be made based on whether the amount of change in bonding accuracy exceeds a threshold. A pass rate may be calculated based on the pass / fail judgment, or a pass map may be created showing the relationship between substrates W that have been passed or failed and those that have passed, and at least one of the pass rate and the pass map may be recorded or displayed.

[0032] As shown in Figures 1C and 1D, the filler liquid FL is a liquid that changes into a solid or semi-solid filler FS. The filler liquid FL may be a solution in which the filler FS (corresponding to the solute) is dissolved in a solvent, or a liquid of the filler FS (a liquid in which the concentration of the filler FS is 100% or nearly 100%), or it may be any other liquid. When the filler liquid FL is a solution containing the filler FS and a solvent, the solvent may be a liquid of a substance more volatile than water, such as IPA (isopropyl alcohol). For example, the filler liquid FL may be a spin-on-glass (SOG) liquid containing a siloxane component (corresponding to the solute) and an alcohol (corresponding to the solvent).

[0033] When the grinding process is initiated, the filler liquid FL in the annular groove WG formed between the outer periphery of the first substrate W1 and the outer periphery of the second substrate W2 has transformed into a filler FS. If necessary, a process for initiating or accelerating the transformation of the filler liquid FL into a filler FS may be performed before the grinding process. For example, when the filler liquid FL transforms into a filler FS by evaporation, a portion of the filler liquid FL may be evaporated by at least one of heating the filler liquid FL and lowering the air pressure. When the filler liquid FL transforms into a filler FS by hardening the filler liquid FL, the filler liquid FL may be hardened by at least one of heating the filler liquid FL and irradiating the filler liquid FL with light. These processes may be performed while the filler liquid FL is being supplied, after the supply of the filler liquid FL has been stopped, or both.

[0034] Next, the substrate bonding apparatus 1 that bonds two substrates W as described above will be described.

[0035] 3 is a schematic plan view of a substrate bonding apparatus 1 according to one embodiment of the present invention. In the following description, the up-down direction, left-right direction, and front-rear direction refer to the up-down direction, left-right direction, and front-rear direction of the substrate bonding apparatus 1 unless otherwise specified. The up-down direction is the vertical direction. The left-right direction and the front-rear direction are two horizontal directions that are perpendicular to each other. The left-right direction is the arrangement direction of multiple carriers CA held on multiple load ports LP. Each carrier CA is held on the load port LP with the opening of the carrier CA facing rearward.

[0036] The substrate bonding apparatus 1 is an apparatus for bonding two disk-shaped substrates W. The substrate bonding apparatus 1 includes a plurality of load ports LP on each of which a plurality of carriers CA, such as FOUPs (Front-Opening Unified Pods), are placed, each carrier CA accommodating a plurality of substrates W, a plurality of processing units 2 for processing the substrates W transferred from the plurality of load ports LP, a transport system TS for transporting the substrates W between the plurality of load ports LP and the plurality of processing units 2, and an outer wall 1a forming an enclosed space accommodating the plurality of processing units 2 and the transport system TS. The substrate bonding apparatus 1 further includes a control device 3 for controlling the substrate bonding apparatus 1.

[0037] 3 shows an example in which three load ports LP are provided. The three load ports LP include a first load port LP1 on which a carrier CA accommodating a first substrate W1 is placed, a second load port LP2 on which a carrier CA accommodating a second substrate W2 is placed, and a third load port LP3 on which a carrier CA accommodating the bonded first and second substrates W1 and W2 is placed. The first load port LP1 and the second load port LP2 are load ports on which carriers CA accommodating substrates W to be bonded in the substrate bonding apparatus 1 are placed. The third load port LP3 is an unload port on which a carrier CA accommodating two substrates W bonded in the substrate bonding apparatus 1 is placed.

[0038] The multiple processing units 2 include a pre-activation aligner 10, an activation unit 20, a pre-bonding cleaning unit 30, a pre-bonding aligner, a coating unit 40, a bonding unit 50, a grinding unit 60, and a post-grinding cleaning unit 70. Fig. 3 shows an example in which two pre-activation aligners 10, two activation units 20, two pre-bonding cleaning units 30, two pre-bonding aligners, and two coating units 40 are provided, and the pre-bonding aligner is integrated with the coating unit 40.

[0039] The pre-activation aligner 10 is a unit that positions the substrate W in the circumferential direction of the substrate W based on the notch or orientation flat. The same is true for the pre-bonding aligner. The activation unit 20 is a unit that performs plasma treatment to activate the front or back surface of the substrate W by bringing plasma into contact with the front or back surface of the substrate W. The pre-bonding cleaning unit 30 is a unit that cleans the substrate W by supplying a cleaning liquid to the substrate W.

[0040] The bonding unit 50 is a unit that bonds two substrates W by bringing them into contact with each other. The coating unit 40 is a unit that supplies a filler liquid to an annular groove WG (see FIG. 1C ) formed between the outer peripheries of the two bonded substrates W. The grinding unit 60 is a unit that thins the two bonded substrates W by grinding the two bonded substrates W. The post-grinding cleaning unit 70 is a unit that cleans the two substrates W by supplying a cleaning liquid to the two substrates W that have been thinned by grinding.

[0041] The transport system TS transports substrates W from the first load port LP1 and the second load port LP2 to the plurality of processing units 2, and transports substrates W from the plurality of processing units 2 to the third load port LP3. The transport system TS further transports substrates W between the plurality of processing units 2. The transport system TS may include at least one transport robot TR that transports one or more substrates W in a horizontal position on a transport path TP indicated by a thick line in Figure 3.

[0042] The transport robot TR includes at least one hand TH that holds one substrate W in a horizontal position. The transport robot TR moves along the transport path TP while holding the substrate W horizontally with the hand TH. Figure 3 shows an example in which the transport path TP extends from each of the first load port LP1 and the second load port LP2 to a plurality of processing units 2, and returns from the plurality of processing units 2 to the third load port LP3.

[0043] The following describes the processing units 2. First, the pre-activation aligner 10 will be described.

[0044] 4A is a schematic diagram showing the interior of the aligner 10 as seen horizontally before activation, and FIG. 4B is a schematic diagram showing the interior of the aligner 10 as seen from directly above before activation.

[0045] 4A and 4B, the pre-activation aligner 10 includes a chamber 11 that forms an internal space in which the substrate W is placed and a passage opening through which the substrate W passes to enter and exit the internal space, and a chuck 14 that holds the substrate W horizontally within the chamber 11. The chamber 11 includes a partition wall 12 that forms the internal space and the passage opening, and a door 13 that moves relative to the partition wall 12 to open and close the passage opening.

[0046] The pre-activation aligner 10 further includes an electric motor 15 that rotates the chuck 14 to rotate the substrate W around a vertical center of rotation A1 that passes through the center of the substrate W held on the chuck 14, an outer periphery position sensor 16 that identifies the orientation of the notch or orientation flat by detecting the contour shape of the substrate W, and a control device 3 that causes the electric motor 15 to rotate the chuck 14 based on the detection value of the outer periphery position sensor 16, thereby stopping the substrate W at a position where the orientation of the notch or orientation flat coincides with a reference direction.

[0047] The chuck 14 may be a mechanical chuck that holds the substrate W horizontally by pressing multiple chuck pins horizontally against the edge surface of the substrate W, or a vacuum chuck that holds the substrate W horizontally by attracting the lower surface of the substrate W to the upper surface of a spin base arranged below the substrate W. Figures 4A and 4B show an example of the latter. In the latter case, the outer periphery position sensor 16 may identify the position of the center of the substrate W by detecting the contour shape of the substrate W. In this case, the pre-activation aligner 10 may further include a centering actuator that moves the chuck 14 horizontally to bring the center of the substrate W closer to the center of rotation A1 of the substrate W.

[0048] An actuator is a device that converts driving energy, such as electrical, fluid, magnetic, thermal, or chemical energy, into mechanical work, i.e., the movement of a tangible object. Actuators include electric motors (rotary motors), linear motors, air cylinders, and other devices. When the movement of the actuator differs from the movement of the object, a motion converter may be provided to convert the movement of the actuator into linear or rotational motion. For example, if the actuator is an electric motor that moves the object linearly, the rotation of the electric motor may be converted into linear motion by a motion converter such as a ball screw and ball nut.

[0049] Next, the activation unit 20 will be described.

[0050] Fig. 5A is a schematic diagram showing the inside of the activation unit 20 as seen horizontally. Fig. 5B is a schematic diagram showing the inside of the activation unit 20 as seen from directly above.

[0051] 5A and 5B , the activation unit 20 includes a chamber 21 that defines an internal space in which the substrate W is placed and a passage through which the substrate W passes to enter and exit the internal space, a lower electrode 24L that horizontally supports the substrate W within the chamber 21, an upper electrode 24u that is positioned above the substrate W held by the lower electrode 24L, a gas pipe 25p that supplies a processing gas between the upper electrode 24u and the lower electrode 24L, a gas valve 25v that opens and closes the gas pipe 25p, a power supply 26 that converts the processing gas between the upper electrode 24u and the lower electrode 24L into plasma, and a vacuum pump 27 that exhausts gas from the internal space. The chamber 21 includes a partition wall 22 that defines the internal space and the passage, and a door 23 that moves relative to the partition wall 22 to open and close the passage.

[0052] Although not shown, the gas valve 25v includes a valve body provided with an annular valve seat through which gas passes, a valve element movable relative to the valve seat, and an actuator that moves the valve element between a closed position in which the valve element contacts the valve seat and an open position in which the valve element is spaced from the valve seat. The actuator may be a pneumatic actuator, an electric actuator, or another type of actuator. The control device 3 (see FIG. 3) controls the actuator to open and close the gas valve 25v.

[0053] Next, the pre-bonding cleaning unit 30 will be described.

[0054] Fig. 6A is a schematic diagram showing the interior of the pre-bonding cleaning unit 30 as viewed horizontally. Fig. 6B is a schematic diagram showing the interior of the pre-bonding cleaning unit 30 as viewed from directly above.

[0055] 6A and 6B , the pre-bonding cleaning unit 30 includes a chamber 31 forming an internal space in which the substrate W is placed and a passage port through which the substrate W passes to enter and exit the internal space, a chuck 34 for horizontally holding the substrate W within the chamber 31, an electric motor 35 for rotating the chuck 34 to rotate the substrate W about a vertical rotation center A1 passing through the center of the substrate W held by the chuck 34, and one or more processing liquid nozzles 36 for discharging a processing liquid such as a cleaning liquid toward the substrate W held by the chuck 34. The chamber 31 includes a partition wall 32 forming the internal space and the passage port, and a door 33 that moves relative to the partition wall 32 to open and close the passage port. The cleaning liquid may be pure water (deionized water (DIW)) or a liquid other than pure water.

[0056] Although not shown, the post-grinding cleaning unit 70 (see FIG. 3) has a configuration similar to that of the pre-bonding cleaning unit 30. Therefore, the post-grinding cleaning unit 70 includes a chamber 31, a chuck 34, an electric motor 35, and a processing liquid nozzle 36. The chamber 31 includes a partition wall 32 and a door 33. The pre-bonding cleaning unit 30 and the post-grinding cleaning unit 70 differ from each other in that the pre-bonding cleaning unit 30 cleans the first substrate W1 or the second substrate W2, whereas the post-grinding cleaning unit 70 cleans the first substrate W1 or the second substrate W2 that has been bonded and ground.

[0057] Next, the coating unit 40 will be described.

[0058] Fig. 7A is a schematic diagram of the interior of the coating unit 40 as viewed horizontally. Fig. 7B is a schematic diagram of the interior of the coating unit 40 as viewed from directly above. Figs. 7C and 7D are schematic diagrams of the filling liquid nozzle 49.

[0059] The application unit 40 includes a pre-bonded aligner. The pre-bonded aligner has a configuration similar to the pre-activated aligner 10 (see FIGS. 4A and 4B ). Therefore, the application unit 40 includes a chamber 11, a partition 12, a door 13, a chuck 14, an electric motor 15, and an outer periphery position sensor 16. In the following, to distinguish between the configuration of the pre-activated aligner 10 and the configuration of the application unit 40, the chamber 11, partition 12, door 13, chuck 14, electric motor 15, and outer periphery position sensor 16 for the application unit 40 will be referred to as a chamber 41, a partition 42, a door 43, a chuck 44, an electric motor 45, and an outer periphery position sensor 46. The chuck 44 is the vacuum chuck described above.

[0060] The coating unit 40 includes at least one filling liquid nozzle 49 that ejects filling liquid toward the substrate W held by the chuck 44. Fig. 7B shows an example in which two filling liquid nozzles 49 are provided. The two filling liquid nozzles 49 are arranged at an interval in the rotation direction Dr of the chuck 44. The two filling liquid nozzles 49 eject filling liquid toward two target positions that are spaced apart in the rotation direction Dr of the chuck 44. Each target position is a position within the outer periphery of the top surface of the substrate W held by the chuck 44.

[0061] 7A and 7B show an example in which the filling liquid nozzle 49 is disposed above the substrate W and ejects the filling liquid in a direction perpendicular to the upper surface of the substrate W. The ejection direction of the filling liquid, which is the direction in which the filling liquid nozzle 49 ejects the filling liquid, may not be vertical, but may be inclined with respect to the upper surface of the substrate W. The ejection direction of the filling liquid may be inclined inward or outward in the radial direction of the substrate W (a direction perpendicular to the center line of the substrate W), or may be inclined upstream or downstream in the rotation direction Dr of the substrate W. The ejection direction of the filling liquid may be inclined in both the radial direction and the rotation direction Dr of the substrate W.

[0062] Filler liquid nozzle 49 is a droplet nozzle that generates multiple droplets of filler liquid that are sprayed toward the object to be coated. The droplet nozzle may be a mist nozzle that ejects liquid in a mist, an inkjet nozzle that forms a line of multiple droplets, or other types of nozzles. Figures 7C and 7D show an example in which filler liquid nozzle 49 is an inkjet nozzle.

[0063] The mist nozzle may be an external-mixing or internal-mixing two-fluid nozzle that generates mist by colliding liquid and gas, or a spray nozzle that generates mist by discharging compressed liquid from an orifice or by utilizing the Venturi effect.

[0064] The inkjet nozzle may be a piezoelectric or thermal inkjet nozzle, or may be an inkjet nozzle other than a piezoelectric or thermal type. The inkjet nozzle may be a large-diameter nozzle 49X having a relatively large diameter nozzle 49x for ejecting droplets, or a small-diameter nozzle 49Y having a relatively small diameter nozzle 49y for ejecting droplets.

[0065] FIG. 7C shows an example of a large-diameter nozzle 49X. FIG. 7D shows an example of a small-diameter nozzle 49Y. The diameter of the injection port 49x of the large-diameter nozzle 49X may be within any of the ranges of 10 μm or less, 8 μm or less, and 3 μm or less, or may be outside these ranges. The same applies to the diameter of the injection port 49y of the small-diameter nozzle 49Y. The area of ​​the injection port 49y of the small-diameter nozzle 49Y is smaller than the area of ​​the injection port 49x of the large-diameter nozzle 49X. When the diameter of the injection port 49x of the large-diameter nozzle 49X exceeds 10 μm, the diameter of the injection port 49y of the small-diameter nozzle 49Y may be within the range of 0.01 μm to 10 μm.

[0066] The filling liquid nozzle 49 may be fixed to the partition wall 42 or may be movable relative to the partition wall 42. When multiple filling liquid nozzles 49 are provided in one application unit 40, at least one filling liquid nozzle 49 may be fixed to the partition wall 42 and the remaining at least one filling liquid nozzle 49 may be movable relative to the partition wall 42.

[0067] 7A and 7B , when the filling liquid nozzles 49 are movable relative to the partition walls 42, the application unit 40 may include nozzle actuators 49a that move the filling liquid nozzles 49 relative to the partition walls 42. One nozzle actuator 49a may be provided for each filling liquid nozzle 49, or one nozzle actuator 49a may be provided for each of a plurality of filling liquid nozzles 49. FIGS. 7A and 7B show an example of the former.

[0068] The nozzle actuator 49a may include at least one of a horizontal actuator that moves the filling liquid nozzle 49 horizontally, a vertical actuator that moves the filling liquid nozzle 49 vertically, and an attitude-changing actuator that changes the attitude of the filling liquid nozzle 49. When moving the filling liquid nozzle 49 in the horizontal and vertical directions, the filling liquid nozzle 49 may be directly or indirectly connected to the horizontal actuator, and the horizontal actuator may be directly or indirectly connected to the vertical actuator.

[0069] 7A and 7B, the coating unit 40 includes a height sensor 47 that measures the height of the substrate W held by the chuck 44. The height sensor 47 measures the height of the upper or lower surface of the substrate W held by the chuck 44. Fig. 7A shows an example in which the height sensor 47 is disposed above the substrate W held by the chuck 44 and measures the height of the upper surface of the substrate W. The height sensor 47 may be a laser sensor or another sensor.

[0070] The height sensor 47 is an optical non-contact sensor that detects the vertical position of the substrate W. When the chuck 44 rotates around the rotation center A1 of the chuck 44 while holding the substrate W, the substrate W moves in the rotation direction Dr of the chuck 44 relative to the height sensor 47, and the position detected by the height sensor 47 moves in the opposite direction to the rotation direction Dr of the chuck 44 relative to the substrate W. Therefore, if the substrate W and the chuck 44 are rotated 360 degrees or more while the height sensor 47 is measuring the height of the substrate W, the height of the substrate W can be measured around the entire circumference of the substrate W.

[0071] By measuring the height of the upper surface of the substrate W over the entire circumference of the substrate W, it is possible to measure the shape of the upper surface of the substrate W over the entire circumference of the substrate W. For example, by measuring the height of the outer periphery of the upper surface of the substrate W, more specifically, the height in the range from the edge of the substrate W to a position inside the edge, over the entire circumference of the substrate W, it is possible to measure the shape of the outer periphery of the upper surface of the substrate W including the edge of the substrate W. Because the shape of the outer periphery of the upper surface of the substrate W is measured for each rotation angle about the rotation center A1 of the chuck 44, it is also possible to measure how the shape of the outer periphery of the upper surface of the substrate W changes depending on the position in the circumferential direction of the substrate W.

[0072] The outer periphery position sensor 46 is an optical non-contact sensor that detects the horizontal position of the outer periphery of the substrate W. When the chuck 44 rotates around the rotation center A1 of the chuck 44 while holding the substrate W, the substrate W moves in the rotation direction Dr of the chuck 44 relative to the outer periphery position sensor 46, and the position detected by the outer periphery position sensor 46 moves in the opposite direction to the rotation direction Dr of the chuck 44 relative to the substrate W. Therefore, if the substrate W and the chuck 44 are rotated 360 degrees or more while the outer periphery position sensor 46 is detecting the outer periphery position of the substrate W, the outer periphery position of the substrate W in the horizontal direction can be detected all around the circumference of the substrate W. This makes it possible to measure the shape of the outer periphery of the substrate W.

[0073] By measuring the shape of the outer periphery of the substrate W held by the chuck 44, it is possible to measure the amount and direction of eccentricity of the substrate W relative to the rotation center A1 of the chuck 44. It is also possible to measure the orientation of the notch or orientation flat relative to the chuck 44. In addition, because the position of the outer periphery of the substrate W is measured for each rotation angle about the rotation center A1 of the chuck 44, it is also possible to measure how the position of the outer periphery of the substrate W in the horizontal direction changes depending on the position of the substrate W in the circumferential direction.

[0074] The coating unit 40 includes a void detector 48 that captures an image of voids in at least one of the filling liquid and the filler on the substrate W held by the chuck 44. The void detector 48 may be an infrared camera or a camera other than an infrared camera, as long as it can capture an image of voids in the filling liquid and the filler. When the void detector 48 is a camera, the image sensor may be either a charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS).

[0075] When the void detector 48 is an infrared camera, the coating unit 40 may include a light source 48s (see FIG. 7A ) that irradiates the outer periphery of the substrate W held by the chuck 44 with infrared light. The light source 48s may be disposed inside or outside the coating unit 40. In the latter case, the light from the light source 48s may be guided into the coating unit 40 by a guide such as an optical fiber. If the presence or absence of voids in the filling liquid and the filling body can be detected without the light source 48s, the light source 48s is not necessary.

[0076] 7B shows an example in which one void detector 48 is provided for each filling liquid nozzle 49. Therefore, in this example, two void detectors 48 are provided. However, this is not limited to this, and one void detector 48 may be provided for each of a plurality of filling liquid nozzles 49. In the example shown in FIG. 7B, the void detector 48 is disposed upstream of the filling liquid nozzle 49 in the rotation direction Dr of the chuck 44. The filling liquid nozzle 49 and the void detector 48 may be disposed within a range of less than 45 degrees with respect to the angle around the rotation center A1 of the chuck 44.

[0077] When the substrate W and chuck 44 are rotated 360 degrees or more while the void detector 48 is photographing the filler liquid and filler on the substrate W held by the chuck 44, images of the filler liquid and filler are captured all around the circumference of the substrate W. This makes it possible to inspect the presence or absence of voids in the filler liquid or filler all around the circumference of the substrate W. Furthermore, the void detector 48 can observe how the shape and position of the filler liquid or filler on the substrate W change depending on the position in the circumferential direction of the substrate W (the direction around the center line of the substrate W).

[0078] Next, a description will be given of the bonding unit 50. Unless otherwise specified, the bonding unit 50 described in this specification bonds substrates under atmospheric pressure.

[0079] 8A and 8B are horizontal schematic views of the inside of the bonding unit 50. Fig. 8A shows the state before the first substrate W1 and the second substrate W2 are bonded, and Fig. 8B shows the state after the first substrate W1 and the second substrate W2 have been bonded.

[0080] 8A and 8B , the bonding unit 50 includes a chamber 51 that forms a passage opening through which the first substrate W1 and the second substrate W2 pass before and after bonding and an internal space in which the first substrate W1 and the second substrate W2 that have passed through the passage opening are placed, a first chuck 54A that holds the first substrate W1 horizontally within the chamber 51, and a second chuck 54B that holds the second substrate W2 horizontally within the chamber 51. The chamber 51 includes a partition wall 52 that forms the internal space and the passage opening, and a door 53 that moves relative to the partition wall 52 to open and close the passage opening.

[0081] The bonding unit 50 further includes a plurality of bonding actuators 55 that bond the first substrate W1 and the second substrate W2 by moving the first chuck 54A and the second chuck 54B relative to each other while they are holding the first substrate W1 and the second substrate W2, and at least one camera 56 that detects the alignment of the first substrate W1 and the second substrate W2 at least either before or after bonding the first substrate W1 and the second substrate W2 by photographing at least one of the first substrate W1 and the second substrate W2.

[0082] The multiple joining actuators 55 may include a horizontal actuator that moves the first chuck 54A and the second chuck 54B relatively in the horizontal direction, a vertical actuator that moves the first chuck 54A and the second chuck 54B relatively in the vertical direction, and a rotational actuator that rotates the first chuck 54A and the second chuck 54B relatively around a vertical line.

[0083] The multiple bonding actuators 55 may include an inversion actuator that rotates the first chuck 54A about a horizontal line to invert the first substrate W1 held by the first chuck 54A upside down. The inversion actuator may also invert the first substrate W1 held by a chuck other than the first chuck 54A upside down. The inversion actuator may also invert the first substrate W1 upside down outside the bonding unit 50. When the hand TH (see FIG. 3) of the transport robot TR can hold the first substrate W1 horizontally facing downward (when the hand TH is a vacuum hand, Bernoulli hand, or the like), the inversion actuator may be part of the transport robot TR.

[0084] The at least one camera 56 may include a first camera 56A that photographs the first substrate W1 before it is bonded to the second substrate W2, a second camera 56B that photographs the second substrate W2 before it is bonded to the first substrate W1, and a third camera 56C that photographs the bonded first substrate W1 and second substrate W2. The first camera 56A may photograph the first substrate W1 held by the first chuck 54A, or may photograph the first substrate W1 held by a chuck other than the first chuck 54A. The same applies to the second camera 56B. The third camera 56C may photograph the bonded substrate W (bonded first substrate W1 and second substrate W2) held by the first chuck 54A or the second chuck 54B, or may photograph the bonded substrate W held by a chuck other than the first chuck 54A or the second chuck 54B. At least one camera 56 may capture an image of at least one of the first substrate W1 and the second substrate W2 outside the bonding unit 50.

[0085] The first camera 56A and the second camera 56B are alignment cameras used to check and adjust the alignment of the first substrate W1 and the second substrate W2 before they are bonded. The third camera 56C is an inspection camera used to check the alignment of the bonded first substrate W1 and the second substrate W2. The inspection camera is an infrared camera that converts infrared light into an electrical signal to generate electronic data of still images or videos. The alignment camera may be an infrared camera or a visible light camera that converts visible light into an electrical signal to generate electronic data of still images or videos.

[0086] Next, the grinding unit 60 will be described.

[0087] Fig. 9A is a schematic diagram showing the interior of the grinding unit 60 as seen horizontally. Fig. 9B is a schematic diagram showing the interior of the grinding unit 60 as seen from directly above.

[0088] 9A and 9B , grinding unit 60 includes a chamber 61 that forms a passage opening through which bonded substrate W, i.e., bonded first substrate W1 and second substrate W2, passes and an internal space in which bonded substrate W that has passed the passage opening is placed, a chuck 64 that holds bonded substrate W horizontally within chamber 61, and an electric motor 65 that rotates chuck 64 to rotate bonded substrate W about a vertical center of rotation A1 that passes through the center of bonded substrate W held by chuck 64. Chamber 61 includes a partition wall 62 that forms the internal space and the passage opening, and a door 63 that moves relative to partition wall 62 to open and close the passage opening.

[0089] Grinding unit 60 further includes a grindstone 66 that is pressed against the upper surface of bonded substrate W held by chuck 64, a horizontal, disc-shaped wheel 67 that holds grindstone 66, an electric motor 68 that rotates grindstone 66 and wheel 67 around a vertical center of rotation that passes through the center of wheel 67, and an elevation actuator 69 that vertically moves grindstone 66 and wheel 67. When grindstone 66 is brought into contact with the upper surface of bonded substrate W while rotating chuck 64 and wheel 67, the entire upper surface of bonded substrate W is ground by grindstone 66.

[0090] Next, the electrical configuration of the substrate bonding apparatus 1 will be described.

[0091] 10 is a block diagram showing the electrical configuration of the substrate bonding apparatus 1. The substrate bonding apparatus 1 includes a control device 3 that controls the electrical and electronic devices provided in the substrate bonding apparatus 1. The control device 3 controls the substrate bonding apparatus 1 to operate as described below. In other words, the control device 3 is programmed to perform the operations described below.

[0092] The control device 3 includes at least one computer. The computer includes a computer main body 3a and a peripheral device 3d connected to the computer main body 3a. The computer main body 3a includes a CPU 3b (central processing unit) that executes various instructions and a memory 3c that stores information. The peripheral device 3d includes a storage 3e that stores information to be transmitted and received between the memory 3c, such as a program P, a reader 3f that reads information from removable media RM, and a communication device 3g that communicates with other devices, such as a host computer HC. The memory 3c and the storage 3e are both examples of storage devices that store information to be transmitted and received between the CPU 3b and the CPU 3b.

[0093] The control device 3 is connected to an input device 3h and a display device 3i. The input device 3h is operated when an operator such as a user or a maintenance technician inputs information into the substrate bonding apparatus 1. The information is displayed on the screen of the display device 3i. The input device 3h may be any of a keyboard, a pointing device, and a touch panel, or may be a device other than these. The substrate bonding apparatus 1 may be provided with a touch panel display that serves as both the input device 3h and the display device 3i.

[0094] The CPU 3b executes a program P stored in the storage 3e. The program P in the storage 3e may be one that has been pre-installed in the control device 3, one that has been sent from a removable medium RM to the storage 3e via the reader 3f, or one that has been sent to the storage 3e from an external device such as a host computer HC via a communication device 3g.

[0095] The memory 3c is a volatile memory that retains its memory only when power is supplied. The storage 3e and the removable medium RM are non-volatile memories that retain their memory even when power is not supplied. The storage 3e is, for example, a magnetic storage device such as a hard disk drive. The removable medium RM is, for example, an optical disk such as a compact disk or a semiconductor memory such as a memory card. The removable medium RM is an example of a computer-readable recording medium on which the program P is recorded. The removable medium RM is a non-transitory tangible recording medium.

[0096] The storage 3e stores a plurality of recipes RC. The recipes RC are information that specifies the processing content, processing conditions, and processing procedures for the substrates W. The plurality of recipes RC differ from one another in at least one of the processing content, processing conditions, and processing procedures for the substrates W. The control device 3 controls the substrate bonding apparatus 1 so that the substrates W are processed in accordance with the recipes RC specified by the host computer HC. The control device 3 is programmed to execute each of the processes described below.

[0097] The recipe RC includes the application amount (total amount of filler liquid supplied to one pre-bonding substrate W), the application start position (position at which supply of filler liquid to the substrate W starts), and the application end position (position at which supply of filler liquid to the substrate W starts to end). In other words, the application amount, etc. are specified in the recipe RC. When the filling liquid nozzle 49 is moved, the path through which the filling liquid nozzle 49 passes is also included in the recipe RC. The user can change the application amount, etc. by editing the recipe RC. The recipe RC may be edited by the user operating the input device 3h, or by the user operating a device other than the substrate bonding apparatus 1, such as a personal computer. In the latter case, the edited recipe RC can be sent to the control device 3 via the communication device 3g.

[0098] Next, a description will be given of application of the filler liquid to the substrate W. First, the shape of the substrate W will be described, and then application of the filler liquid to the substrate W will be described.

[0099] Fig. 11A is a schematic cross-sectional view of the outer periphery of a substrate W. Fig. 11B is a schematic horizontal view of the interior of the coating unit 40. Fig. 11C is a schematic cross-sectional view showing a state in which filler liquid FL is being supplied to the outer periphery O1 of the bonding surface WA of the substrate W. Fig. 11D is a schematic cross-sectional view showing a state in which a void V1 in a filler FS on the substrate W is being detected by a void detector 48. Fig. 11E is a schematic cross-sectional view showing a state in which a void V1 and a void V2 between two bonded substrates W are being detected by the void detector 48.

[0100] The outer periphery of the substrate W is also referred to as a bevel portion. Fig. 11A shows an example in which the cross section of the outer periphery of the substrate W is semicircular or parabolic. The cross section of the outer periphery of the substrate W may have a shape other than semicircular or parabolic, such as a trapezoidal shape. The following describes a state in which the front and back surfaces of the substrate W are horizontal.

[0101] The outer surface of the substrate W includes a bonding surface WA that comes into contact with another substrate W, a non-bonding surface WN that does not come into contact with another substrate W, and a tip WE that is located outermost on the outer surface of the substrate W. The tip WE of the substrate W is a circular line or surface that connects the outer periphery of the bonding surface WA and the outer periphery of the non-bonding surface WN. The edge surface of the substrate W is a region of a predetermined range that includes the tip WE of the substrate W.

[0102] The bonding surface WA of the substrate W includes a horizontal, flat, circular flat portion F1 and an annular outer periphery O1 extending from the outer periphery of the flat portion F1 to the tip WE so as to descend as it approaches the tip WE. The non-bonding surface WN of the substrate W includes a horizontal, flat, circular flat portion F2 and an annular outer periphery O2 extending from the outer periphery of the flat portion F2 to the tip WE so as to ascend as it approaches the tip WE.

[0103] The flat portion F1 of the bonding surface WA corresponds to a device formation region where a device is formed. The flat portion F1 of the bonding surface WA is parallel to the flat portion F2 of the non-bonding surface WN. The center of the flat portion F1 of the bonding surface WA is located on the center line of the substrate W. The same is true for the center of the flat portion F2 of the non-bonding surface WN. When the cross section of the outer periphery of the substrate W is semicircular or parabolic, the cross sections of the outer periphery O1 and O2 are arc-shaped. When the cross section of the outer periphery of the substrate W is trapezoidal, the cross sections of the outer periphery O1 and O2 are linear.

[0104] 11A , when two substrates W are bonded together, the outer peripheries of the two bonded substrates W form an annular groove WG that opens at the edge faces of the two substrates W. The annular groove WG is formed between the two bonded substrates W by the outer peripheries of the two substrates W. The annular groove WG is continuous around the entire periphery of the bonded substrate W. The thickness direction of the two bonded substrates W corresponds to the width direction of the annular groove WG, and the radial direction of the two bonded substrates W (the direction perpendicular to the center line of the substrates W) corresponds to the depth direction of the annular groove WG. The depth of the annular groove WG increases continuously or stepwise as one approaches the center of the annular groove WG in the width direction of the annular groove WG.

[0105] As described above, after two substrates W are bonded together, the bonded substrate W, i.e., one of the two bonded substrates W, is ground down using a grindstone 66 (see FIG. 9A ). The thickness of the outer periphery of the substrate W decreases toward the edge of the substrate W. Near the edge of the substrate W, the outer peripheries of the two bonded substrates W are separated from each other, forming a gap corresponding to the annular groove WG. If the bonded substrate W is ground without a filler FS (see FIG. 1D ) in the annular groove WG, a force is applied to the outer periphery of the substrate W from the grindstone 66, which may cause the outer periphery of one substrate W to bend toward the outer periphery of the other substrate W. To mitigate this, a filler liquid FL that changes into a solid or semi-solid filler FS must be supplied to the annular groove WG.

[0106] However, when the filler liquid FL is supplied to the annular groove WG after two substrates W are bonded together, it may be difficult for the filler liquid FL to reach the bottom of the annular groove WG. Figure 11A shows an example of a cross section of a substrate W in which such a phenomenon occurs.

[0107] 11A , a step Wb is formed by an outer periphery O1 of the bonding surface WA of the substrate W. The outer periphery O1 of the bonding surface WA corresponds to a step forming portion that forms the annular step Wb on the bonding surface WA. The outer periphery O1 of the bonding surface WA is concentric with the flat portion F1 of the bonding surface WA and has a continuous annular shape around the entire circumference of the substrate W. The outer periphery O1 of the bonding surface WA is recessed from the flat portion F1 of the bonding surface WA toward the non-bonding surface WN. The height of the step Wb is less than ¼ of the thickness of the substrate W. The height of the step Wb is, for example, within a range of 0.1 μm to 1.0 μm.

[0108] The black circle in Figure 11A indicates the position of the outer periphery (outer edge) of the flat portion F2 of the non-bonding surface WN. The outer periphery (outer edge) of the flat portion F1 of the bonding surface WA is located more inward than the outer periphery (outer edge) of the flat portion F2 of the non-bonding surface WN. Therefore, the diameter of the flat portion F1 of the bonding surface WA is smaller than the diameter of the flat portion F2 of the non-bonding surface WN. The outer periphery of the flat portion F1 of the bonding surface WA may be located more inward than or more outward than the outer periphery of the flat portion of the bonding surface of another substrate W (first substrate W1 in Figure 11A).

[0109] When two substrates W having a step Wb as shown in Figure 11A, or when one substrate W having a step Wb and another substrate W without a step Wb are bonded together, a long, thin gap is formed between the two substrates W. This gap forms the bottom of the annular groove WG. Even if a filler liquid is supplied to the annular groove WG having such a gap, it is difficult for the filler liquid to reach the bottom of the annular groove WG. Therefore, the filler liquid is applied to the bonding surface WA of one or both of the two substrates W before, rather than after, the two substrates W are bonded together.

[0110] 11B, when the filling liquid FL is to be applied to the outer periphery O1 of the bonding surface WA of the substrate W before it is bonded, the substrate W is carried into the coating unit 40 by the transport robot TR (see FIG. 3) and held horizontally by the chuck 44. This allows the substrate W to be held horizontally with the front surface of the substrate W, which is the bonding surface WA, facing upward. In this state, while the substrate W is being rotated by the chuck 44, the filling liquid FL is discharged from the filling liquid nozzle 49 toward the outer periphery O1 of the bonding surface WA of the substrate W.

[0111] The filling liquid FL ejected from the filling liquid nozzle 49 is applied to the outer periphery of the upper surface of the substrate W. The outer periphery of the upper surface of the substrate W corresponds to the outer periphery O1 of the bonding surface WA, which is an example of a step-forming portion. FIG. 11C shows an example in which the filling liquid nozzle 49 is an inkjet nozzle. In this example, multiple droplets of the filling liquid FL ejected from the filling liquid nozzle 49 are scattered in approximately the same direction toward the outer periphery of the upper surface of the substrate W. These droplets collide with the outer periphery of the upper surface of the substrate W. As a result, the filling liquid FL is applied to the outer periphery of the upper surface of the substrate W.

[0112] The droplets of the fill liquid FL applied to the outer periphery of the upper surface of the substrate W remain at or near the position where they collided with the substrate W due to the viscosity of the fill liquid FL and the force acting on the fill liquid FL from the substrate W. Subsequent droplets of the fill liquid FL collide with at least one of the upper surface of the substrate W and the fill liquid FL adhering to the upper surface of the substrate W, and remain at or near the position where they collided. As a result, the fill liquid FL is deposited on the outer periphery of the upper surface of the substrate W.

[0113] The filler liquid FL on the substrate W changes into the filler FS while remaining in contact with the substrate W. If the filler liquid FL has changed into the filler FS when grinding of the bonded substrate W begins, the filler liquid FL may change into the filler FS while the filler liquid nozzle 49 is discharging the filler liquid FL, or may change into the filler FS after the filler liquid nozzle 49 stops discharging the filler liquid FL. In either case, a process may be performed to cause or promote the change from the filler liquid FL to the filler FS.

[0114] The filling liquid nozzle 49 ejects the filling liquid FL toward the annular step Wb formed by the outer periphery of the top surface of the substrate W, i.e., toward the inner periphery of the outer periphery O1 of the bonding surface WA, which coincides with the outer periphery of the flat portion F1 of the bonding surface WA. If the filling liquid nozzle 49 is a droplet nozzle such as an inkjet nozzle, the control device 3 causes the nozzle actuator 49a to move the filling liquid nozzle 49 in the radial direction of the substrate W, while injecting droplets of the filling liquid FL, so that the filling liquid FL does not collide with the top surface of the substrate W at a position inside the step Wb. This causes the filling liquid FL to deposit on the outer periphery of the top surface of the substrate W so as to eliminate or reduce the step Wb.

[0115] The area to which the filler liquid FL is applied may be the entire area from the step Wb on the upper surface of the substrate W to the leading edge WE of the substrate W, or a portion of the area. Figure 11C shows an example of the latter. In the latter case, the filler liquid FL may be applied to at least a portion of the area outside the outer periphery of the flat portion F1 of the bonding surface WA and inside the outer periphery of the flat portion F2 of the non-bonding surface WN. As long as the step Wb is eliminated or reduced and there is no problem in bonding the two substrates W, the thickness of the filler liquid FL on the substrate W may be uniform or may vary depending on the position in at least one of the circumferential and radial directions of the substrate W. Figure 11D shows an example of the latter. The thickness of the filler FS is equal to or approximately equal to the thickness of the filler liquid FL.

[0116] If the radial distance from the center of rotation A1 of the substrate W is the same, the thickness of the filler liquid FL on the substrate W is constant or approximately constant. Near the step Wb, the thickness of the filler liquid FL is constant or approximately constant regardless of the radial position of the substrate W. The thickness of the filler liquid FL on the substrate W increases and then decreases as it approaches the front end WE of the substrate W. Near the step Wb, the thickness of the filler liquid FL on the substrate W is equal to or approximately equal to the height of the step Wb, or is smaller than the height of the step Wb. Therefore, when two substrates W are bonded together, excess filler liquid FL can be prevented from moving between the joining surfaces WA of the two substrates W.

[0117] The radial distance from the center of rotation A1 of the substrate W to the leading edge WE of the substrate W can change depending on the angle around the center of rotation A1 of the substrate W. The height of the outer periphery of the substrate W can also change depending on the angle around the center of rotation A1 of the substrate W. Therefore, the position of the outer periphery of the top surface of the substrate W can change in at least one of the radial and vertical directions depending on the angle around the center of rotation A1 of the substrate W.

[0118] The control device 3 may reduce the change in the distance from the filling liquid nozzle 49 to the outer periphery of the top surface of the substrate W by causing the nozzle actuator 49a to move the filling liquid nozzle 49 in accordance with the change in the position of the outer periphery of the top surface of the substrate W in at least one of the radial and vertical directions. In this case, the control device 3 may measure the change in the position of the outer periphery of the top surface of the substrate W over the entire circumference of the substrate W and then cause the filling liquid nozzle 49 to start spraying the filling liquid FL toward the rotating substrate W, or may cause the filling liquid nozzle 49 to spray the filling liquid FL toward the rotating substrate W while measuring the change in the position of the outer periphery of the top surface of the substrate W.

[0119] 11B are examples of position detectors that detect the position of the outer periphery of the substrate W. Changes in the position of the outer periphery of the top surface of the substrate W may be detected by any one of the outer periphery position sensor 46, the height sensor 47, and the void detector 48, or by two or more of them. The height sensor 47 detects heights within a certain range in the radial direction, and therefore can also detect the shape of the outer periphery of the top surface of the substrate W and changes therein.

[0120] 11B shows an example in which the filling liquid nozzle 49 is caused to spray the filling liquid FL toward the rotating substrate W while the void detector 48 measures changes in the position and shape of the outer periphery of the top surface of the substrate W. In this example, the void detector 48 is disposed upstream of the filling liquid nozzle 49 in the rotation direction of the substrate W (see FIG. 7B ). Since the difference in rotation angle between the void detector 48 and the filling liquid nozzle 49 (the difference in angle around the center of rotation A1 of the substrate W) and the rotation speed of the substrate W are known, the filling liquid nozzle 49 can be moved relative to the substrate W in accordance with these and the amount and direction of change in the position of the outer periphery of the top surface of the substrate W.

[0121] Not only the position of the outer periphery of the upper surface of the substrate W, but also the shape of the outer periphery of the upper surface of the substrate W may change depending on the angle around the center of rotation A1 of the substrate W. When measuring changes in the shape of the outer periphery of the upper surface of the substrate W using at least one of the height sensor 47 and the void detector 48, the flow rate of the fill liquid FL sprayed from the fill liquid nozzle 49 (the amount of fill liquid FL sprayed from the fill liquid nozzle 49 per unit time) may be changed in accordance with the changes. In this way, it is possible to reduce variations in the height of the surface of the fill liquid FL at multiple positions on a circle concentric with the substrate W. The control device 3 may change the flow rate of the fill liquid FL regardless of whether or not changes in the shape of the outer periphery of the upper surface of the substrate W are measured.

[0122] When applying the filler liquid FL to a plurality of substrates W, the positions of the outer peripheries of the upper surfaces of the substrates W may vary in a similar manner among these substrates W. Therefore, the control device 3 may reduce the variation in the distance from the filler liquid nozzle 49 to the outer periphery of the upper surface of the substrate W by causing the nozzle actuator 49a to move the filler liquid nozzle 49 in accordance with the change in the position of the outer periphery of the upper surface of another substrate W. That is, as shown in FIG. 11C , the control device 3 may store measurement data D1 obtained when measuring the change in the position of the outer periphery of the upper surface of another substrate W, and cause the nozzle actuator 49a to move the filler liquid nozzle 49 based on this measurement data D1. Alternatively, the control device 3 may cause the void detector 48 or the like to measure the change in the position of the outer periphery of the upper surface of the substrate W each time a different substrate W is placed on the chuck 44.

[0123] After the filler liquid FL is applied to the outer periphery of the upper surface of the substrate W, this substrate W is bonded to another substrate W. If a step Wb is formed not only on the outer periphery O1 of the bonding surface WA of one substrate W but also on the outer periphery O1 of the bonding surface WA of the other substrate W, the two substrates W may be bonded together after applying the filler liquid FL to the outer periphery O1 of the bonding surface WA of the other substrate W, or the two substrates W may be bonded together without applying the filler liquid FL to the outer periphery O1 of the bonding surface WA of the other substrate W. In either case, the filler liquid FL or filler FS is disposed between the outer peripheries of the two substrates W, thereby reducing the space within the annular groove WG formed between the outer peripheries of the two substrates W.

[0124] In this way, the filling liquid FL is applied to the outer peripheral portion O1 of the bonding surface WA of the substrate W so that the filling liquid does not adhere to the flat portion F1 of the bonding surface WA of the substrate W. As shown in Fig. 11D, after the supply of the filling liquid FL is stopped, the presence or absence of a coating defect may be detected by observing the inside of the filler FS on the substrate W with a void detector 48. Fig. 11D shows an example in which a void V1 in the filler FS is detected by the void detector 48.

[0125] After the two substrates W are bonded together, the bonded substrate W may be held by the chuck 44. As shown in FIG. 11E , the void detector 48 can detect a void V1 in the filler liquid FL or filler FS in the annular groove WG of the bonded substrate W held by the chuck 44. The void detector 48 can also detect a void V2 between the bonding surfaces WA of the two bonded substrates W. To detect the void V2, the void detector 48 may be moved above or below the bonded substrate W held by the chuck 44, or another void detector 48 may be positioned above or below the bonded substrate W held by the chuck 44. The third camera 56C of the bonding unit 50 (see FIG. 8A ) can also detect the void V1 and the void V2 in the bonded substrate W held by the second chuck 54B.

[0126] Filler liquid is applied only to the outer periphery O1 of the bonding surface WA of each substrate W, and after the two substrates W are bonded together, the bonded substrate W is ground. When grinding of the bonded substrate W begins, the filler liquid FL in the annular groove WG has changed into filler FS. When the bonded substrate W, i.e., one of the two bonded substrates W, is ground with a grindstone 66, the outer periphery of the bonded substrate W is supported by the filler FS. This prevents or reduces chipping, which occurs when the edge of the thinned substrate W breaks off, and the associated generation of particles. As a result, the number of particles adhering to devices can be reduced, thereby increasing device yield.

[0127] Next, the effects of this embodiment will be described.

[0128] In this embodiment, filler liquid is not supplied after bonding the two substrates W, but is supplied only to the outer periphery O1 of the bonding surfaces WA of the substrates W before bonding the two substrates W. Then, the two substrates W to which filler liquid has been applied are bonded, or a substrate W to which filler liquid has been applied and a substrate W to which filler liquid has not been applied are bonded. Therefore, filler liquid can be placed at a deeper position in the annular groove WG than when filler liquid is supplied to the annular groove WG formed between the outer peripheries of the two substrates W after bonding the two substrates W.

[0129] In this embodiment, the outer periphery O1 of the bonding surface WA of the substrate W is recessed from the outer periphery of the flat portion F1 of the bonding surface WA of the substrate W, forming a step Wb. If such a step Wb is present on the bonding surface WA of the substrate W, when this substrate W is bonded to another substrate W, a long, narrow gap is formed between the two substrates W. This gap corresponds to the bottom of the annular groove WG. If such a gap exists, even if filler liquid is supplied after the two substrates W are bonded, the filler liquid will not easily reach the bottom of the annular groove WG. The filler liquid nozzle 49 supplies filler liquid only to the outer periphery O1 of the bonding surface WA of the substrates W before bonding the two substrates W. This allows the filler liquid to be placed at the bottom of the annular groove WG, even if the bottom of the annular groove WG is long and narrow.

[0130] In this embodiment, multiple droplets of filler liquid are sprayed toward the outer periphery O1 of the bonding surface WA of the substrate W held by the chuck 44. This allows for more precise control of the amount of filler liquid supplied to the outer periphery O1 of the bonding surface WA of the substrate W than when the filler liquid is continuously sprayed. If the outer periphery O1 of the bonding surface WA of the substrate W forms a step Wb recessed from the outer periphery of the flat portion F1 of the bonding surface WA of the substrate W, when a large amount of filler liquid is supplied to the outer periphery O1 of the bonding surface WA of the substrate W, excess filler liquid may move to the flat portion F1 of the bonding surface WA of the substrate W. By precisely controlling the amount of filler liquid, it is possible to eliminate or reduce such filler liquid.

[0131] In this embodiment, the position of the outer periphery of the substrate W held by the chuck 44 is detected, and the nozzle actuator 49a is caused to move the filling liquid nozzle 49 in accordance with the detected position. As a result, the filling liquid nozzle 49 moves in at least one of the horizontal and vertical directions in accordance with changes in the position of the outer periphery of the substrate W, thereby making it possible to reduce changes in the distance from the filling liquid nozzle 49 to the substrate W that occur as the substrate W rotates. Therefore, it is possible to accurately control the position to which the filling liquid is supplied. If the amount of filling liquid FL discharged per unit time from the filling liquid nozzle 49 is changed in accordance with the detected position, it is possible to reduce variations in the height of the surface of the filling liquid FL at multiple positions on a circle concentric with the substrate W.

[0132] In this embodiment, the outer periphery position sensor 46, the height sensor 47, and the void detector 48 correspond to the position detector. The control device 3 stores measurement data D1 (see FIG. 11C ) obtained when the position detector detects the position of the outer periphery of another substrate W. The control device 3 controls the nozzle actuator 49a to move the filler liquid nozzle 49 based on this measurement data D1. When filling liquid is applied to multiple substrates W, the positions of the outer peripheries of the substrates W may change in the same manner between these substrates W. In such a case, by using the measurement data D1 of the other substrate W, it is possible to reduce the change in the distance from the filler liquid nozzle 49 to the substrate W while shortening the time required to complete the supply of filler liquid, compared to detecting the position of the outer periphery of the substrate W each time.

[0133] In this embodiment, a substrate bonding apparatus 1 that bonds two substrates W is provided with a coating unit 40. As described above, the coating unit 40 supplies filler liquid only to the outer periphery O1 of the bonding surfaces WA of the substrates W. This not only shortens the time from when the filler liquid is applied to one or both of the two substrates W until the two substrates W are bonded together, but also allows the filler liquid to be disposed at a deeper position within the annular groove WG.

[0134] In this embodiment, the substrate bonding apparatus 1 is provided with not only the bonding unit 50 and the coating unit 40, but also a grinding unit 60 that grinds the bonded substrates W coated with the filler liquid. This reduces the time required from bonding two substrates W to grinding the two bonded substrates W. The filler liquid applied to the bonded substrates W changes into a solid or semi-solid filler. This allows the bonded substrates W to be ground while preventing the outer peripheries of the substrates W from being bent by the force applied by the grindstone 66.

[0135] Next, another embodiment will be described.

[0136] Instead of applying the filler liquid to the entire circumference of the substrate W, the filler liquid may be applied to only a partial area in the circumferential direction of the substrate W. The area surrounded by the two-dot chain line in Fig. 12 indicates the area to which the filler liquid is applied. In this example, the filler liquid is applied to only four areas spaced apart in the circumferential direction of the substrate W.

[0137] Devices such as transistors are formed on the surface of the substrate W, which corresponds to the device formation surface. The device region and non-device region are both regions within the surface of the substrate W. In FIG. 12 , the outer edge of the device region is indicated by a thick line. The device region is a region where devices such as transistors and patterns exist. The non-device region is a region where no devices or patterns exist. The non-device region is a ring-shaped region around the device region.

[0138] The shortest distance from the outer periphery of the substrate W to the outer edge of the device region may vary depending on the position on the outer periphery of the substrate W. If this shortest distance is relatively short, a relatively large force is likely to be applied from the grinding wheel 66 (see FIG. 9A ) to devices located at the edge of the device region when the bonded substrate W is being ground. If cracks or chips that occur on the outer periphery of the bonded substrate W during grinding reach devices located at the edge of the device region, the devices (including the cracks, etc.) will become defective. The shorter this shortest distance, the more likely device defects will occur. As shown in FIG. 12 , filler liquid may be applied only to multiple areas (areas surrounded by two-dot chain lines) where the shortest distance is relatively short. This prevents large forces from being applied to devices located at the edge of the device region, while shortening the time required to apply filler liquid compared to applying filler liquid to the entire circumference of the substrate W.

[0139] The filling liquid nozzle 49 may continuously eject the filling liquid so as to form a continuous liquid column from the filling liquid nozzle 49 to the substrate W, or may spray a plurality of droplets of the filling liquid toward the substrate W and then continuously eject the filling liquid so as to form a continuous liquid column from the filling liquid nozzle 49 to the substrate W. In the latter case, a droplet nozzle that sprays a plurality of droplets of the filling liquid toward the substrate W and a liquid column nozzle that continuously ejects the filling liquid so as to form a continuous liquid column from the filling liquid nozzle 49 to the substrate W may be provided.

[0140] If the filling liquid is continuously discharged so as to form a continuous liquid column from the filling liquid nozzle 49 to the substrate W after a plurality of droplets of the filling liquid are sprayed toward the substrate W, the position to which the filling liquid is supplied can be precisely controlled at first, and the filling liquid can be supplied at high speed thereafter. Therefore, the time required to complete the supply of the filling liquid can be shortened compared to the case where a plurality of droplets of the filling liquid are sprayed from start to finish.

[0141] 7C and 7D , the filling liquid nozzle 49 may be composed of a large-diameter nozzle 49X and a small-diameter nozzle 49Y. In this case, droplets of the filling liquid sprayed from the spray port 49y of the small-diameter nozzle 49Y may be supplied to the outer periphery O1 of the bonding surface WA of the substrate W. Then, droplets of the filling liquid sprayed from the spray port 49x of the large-diameter nozzle 49X may be supplied to the outer periphery O1 of the bonding surface WA of the substrate W. In this way, it is possible to make it difficult for voids to occur at the interface between the filling liquid and the substrate W, and to shorten the time required to apply the filling liquid.

[0142] Grinding unit 60 may be omitted from substrate bonding apparatus 1. Coating unit 40 may be omitted from substrate bonding apparatus 1. In other words, coating unit 40 may be a device separate from substrate bonding apparatus 1 and arranged outside outer wall 1 a of substrate bonding apparatus 1.

[0143] The substrate bonding apparatus 1 is not limited to an apparatus for bonding two disk-shaped substrates W, but may also be an apparatus for bonding two polygonal substrates W.

[0144] Any two or more of the above-described features may be combined. Any two or more of the above-described steps may be combined.

[0145] Although the embodiments of the present invention have been described in detail, these are merely examples used to clarify the technical contents of the present invention, and the present invention should not be construed as being limited to these examples. The spirit and scope of the present invention are limited only by the appended claims.

[0146] This application claims priority from Japanese Patent Application No. 2023-188939 filed on November 2, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A coating unit comprising: a chuck that holds a substrate having a bonding surface to be bonded to another substrate and rotates about an axis that is perpendicular to a main surface of the substrate and passes through the center of the main surface; and a filling liquid nozzle that supplies filling liquid only to the outer periphery of the bonding surface of the substrate by ejecting filling liquid that changes into a solid or semi-solid filling body toward the bonding surface of the substrate held by the chuck.

2. The coating unit of claim 1, wherein the joining surface of the substrate includes a flat portion that is joined to another substrate, and an outer periphery that is recessed from the outer periphery of the flat portion toward the non-joining surface of the substrate opposite the joining surface.

3. The coating unit described in claim 1 or 2, wherein the filling liquid nozzle is a droplet nozzle that supplies the filling liquid only to the outer periphery of the joining surface of the substrate by spraying multiple droplets of the filling liquid toward the outer periphery of the joining surface of the substrate held by the chuck.

4. The coating unit described in claim 3, wherein the droplet nozzle includes a large-diameter nozzle that sprays multiple droplets of the filling liquid from a nozzle toward the outer periphery of the joining surface of the substrate held by the chuck, and a small-diameter nozzle that sprays multiple droplets of the filling liquid from a nozzle having an area smaller than the nozzle of the large-diameter nozzle toward the outer periphery of the joining surface of the substrate held by the chuck.

5. A coating unit according to any one of claims 1 to 4, further comprising: a position detector that detects the position of the outer periphery of the substrate held by the chuck; and a nozzle actuator that moves the filling liquid nozzle in accordance with the position of the outer periphery detected by the position detector.

6. A coating unit as described in claim 5, further including a control device which performs at least one of the following in response to the position of the outer periphery of another substrate detected by the position detector: position control which causes the nozzle actuator to move the filling liquid nozzle; and flow rate control which changes the amount of the filling liquid sprayed from the filling liquid nozzle per unit time in accordance with the position of the outer periphery detected by the position detector while causing the position detector to detect the position of the outer periphery of the substrate held by the chuck.

7. A substrate bonding device comprising: an application unit which applies a filling liquid which changes into a solid or semi-solid filling body to a substrate; and a bonding unit which bonds two substrates, at least one of which has the filling liquid applied thereto; wherein the application unit includes: a chuck which holds a substrate having a bonding surface to be bonded to another substrate, and which rotates about an axis which is perpendicular to a main surface of the substrate and passes through the center of the main surface; and a filling liquid nozzle which supplies the filling liquid only to the outer periphery of the bonding surface of the substrate by discharging the filling liquid toward the bonding surface of the substrate held by the chuck.

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