Joining device and joining method

Abstract

To improve the bonding accuracy of the circuit board. [Solution] A bonding apparatus according to one aspect of the present disclosure comprises a first holding part, a second holding part, and a striker. The first holding part holds the first substrate from above. The second holding part is positioned below the first holding part and holds the second substrate to be bonded to the first substrate from below. The second holding part comprises a main body facing the lower surface of the second substrate, a first rib provided circumferentially on the main body and in contact with the outer circumference of the lower surface of the second substrate, a second rib provided circumferentially on the central side of the main body relative to the first rib, a heating part for heating the first rib, and an insulating space located between the first rib and the second rib. The striker presses the center of the first substrate held by the first holding part from above.

Description

Technical Field

[0001] The present disclosure relates to a bonding device and a bonding method.

Background Art

[0002] Patent Document 1 discloses a bonding device for bonding substrates to each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique for improving the bonding accuracy of substrates.

Means for Solving the Problems

[0005] The bonding device according to one aspect of the present disclosure includes a first holding portion, a second holding portion, and a striker. The first holding portion holds a first substrate from above. The second holding portion is disposed below the first holding portion and holds a second substrate to be bonded to the first substrate from below. The second holding portion includes a main body portion facing the lower surface of the second substrate, a first rib provided circumferentially on the main body portion and contacting the outer peripheral portion of the lower surface of the second substrate, a second rib provided circumferentially on the central side of the main body portion with respect to the first rib, a heating portion for heating the first rib, and a heat insulation space located between the first rib and the second rib. The striker presses the central portion of the first substrate held by the first holding portion from above.

Effects of the Invention

[0006] According to the present disclosure, the bonding accuracy of substrates can be improved.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of the joining system according to the embodiment. [Figure 2] Figure 2 is a schematic diagram showing the state of the first substrate and the second substrate before bonding according to the embodiment. [Figure 3] Figure 3 is a schematic diagram illustrating an example of how the bonding area expands. [Figure 4] Figure 4 is a schematic diagram showing the configuration of a joining device according to an embodiment. [Figure 5] Figure 5 is a plan view of the second holding part according to the embodiment, viewed from above. [Figure 6] Figure 6 is a schematic diagram showing the configuration of the outer periphery of the second retaining part according to the embodiment. [Figure 7] Figure 7 is a plan view of the second holding part according to the embodiment, viewed from below. [Figure 8] Figure 8 is a flowchart showing the steps of the process performed by the joining system according to the embodiment. [Modes for carrying out the invention]

[0008] The embodiments for implementing the joining apparatus according to this disclosure (hereinafter referred to as "embodiments") will be described in detail below with reference to the drawings. Note that these embodiments do not limit the joining apparatus and joining method according to this disclosure. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0009] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations, for example, in manufacturing accuracy or installation accuracy.

[0010] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown with the positive Z axis as the vertically upward direction. Also, the direction of rotation with the vertical axis as the center of rotation is sometimes referred to as the θ direction.

[0011] <Configuration of the joining system> First, the configuration of the bonding system according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the configuration of the bonding system according to the embodiment. Figure 2 is a schematic diagram showing the state of the first substrate and the second substrate before bonding according to the embodiment.

[0012] The bonding system 1 shown in Figure 1 forms a polymerized substrate T by bonding a first substrate W1 and a second substrate W2 (see Figure 2).

[0013] The first substrate W1 and the second substrate W2 are, for example, single-crystal silicon wafers, and multiple electronic circuits are formed on their surfaces. The first substrate W1 and the second substrate W2 are approximately the same diameter. One of the first substrate W1 and the second substrate W2 may be, for example, a substrate on which no electronic circuits are formed.

[0014] In the following, as shown in Figure 2, the side of the first substrate W1 that is joined to the second substrate W2 will be referred to as the "joining surface W1j," and the side opposite to the joining surface W1j will be referred to as the "non-joining surface W1n." Similarly, the side of the second substrate W2 that is joined to the first substrate W1 will be referred to as the "joining surface W2j," and the side opposite to the joining surface W2j will be referred to as the "non-joining surface W2n."

[0015] As shown in Figure 1, the joining system 1 comprises an input / output station 2 and a processing station 3. The input / output station 2 is located on the negative X-axis side of the processing station 3 and is integrally connected to the processing station 3.

[0016] The loading / unloading station 2 includes a mounting table 10 and a transfer area 20. The mounting table 10 includes a plurality of mounting plates 11. On each mounting plate 11, cassettes C1 to C4 for accommodating a plurality of (for example, 25) substrates in a horizontal state are respectively placed. Cassette C1 can accommodate a plurality of first substrates W1, cassette C2 can accommodate a plurality of second substrates W2, and cassette C3 can accommodate a plurality of laminated substrates T. Cassette C4 is, for example, a cassette for collecting substrates with defects. Note that the number of cassettes C1 to C4 placed on the mounting plate 11 is not limited to that shown in the figure.

[0017] The transfer area 20 is arranged adjacent to the positive X-axis side of the mounting table 10. In the transfer area 20, a transfer path 21 extending in the Y-axis direction and a transfer device 22 movable along the transfer path 21 are provided. The transfer device 22 is movable not only in the Y-axis direction but also in the X-axis direction and is rotatable around the Z-axis. The transfer device 22 transfers the first substrate W1, the second substrate W2, and the laminated substrate T between the cassettes C1 to C4 placed on the mounting plate 11 and the third processing block G3 of the processing station 3 described later.

[0018] The processing station 3 is provided with, for example, three processing blocks G1, G2, and G3. The first processing block G1 is arranged on the back side (the positive Y-axis side in FIG. 1) of the processing station 3. Also, the second processing block G2 is arranged on the front side (the negative Y-axis side in FIG. 1) of the processing station 3, and the third processing block G3 is arranged on the loading / unloading station 2 side (the negative X-axis side in FIG. 1) of the processing station 3.

[0019] In the first processing block G1, a surface modification device 30 for modifying the bonding surfaces W1j and W2j of the first substrate W1 and the second substrate W2 is arranged. The surface modification device 30 modifies the bonding surfaces W1j and W2j so that they are easily hydrophilized by cutting the SiO2 bonds on the bonding surfaces W1j and W2j of the first substrate W1 and the second substrate W2 to form single-bonded SiO.

[0020] Specifically, in the surface modification apparatus 30, for example, under a reduced pressure atmosphere, oxygen gas or nitrogen gas, which is the processing gas, is excited, plasma-generated, and ionized. Then, these oxygen ions or nitrogen ions are irradiated onto the bonding surfaces W1j and W2j of the first substrate W1 and the second substrate W2, thereby plasma-treated and modified the bonding surfaces W1j and W2j. Note that the processing gas is not limited to oxygen gas, but may also be nitrogen gas, argon gas, helium gas, etc.

[0021] Furthermore, a surface hydrophilization device 40 is located in the first processing block G1. The surface hydrophilization device 40 hydrophilizes the bonding surfaces W1j and W2j of the first substrate W1 and the second substrate W2 with, for example, pure water, and also cleans the bonding surfaces W1j and W2j. Specifically, the surface hydrophilization device 40 supplies pure water onto the first substrate W1 or the second substrate W2 while rotating the substrate, for example, the first substrate W1 or the second substrate W2 held in a spin chuck. As a result, the pure water supplied onto the first substrate W1 or the second substrate W2 diffuses over the bonding surfaces W1j and W2j of the first substrate W1 or the second substrate W2, and the bonding surfaces W1j and W2j are hydrophilized.

[0022] Here, an example is shown where the surface modification device 30 and the surface hydrophilization device 40 are arranged side by side, but the surface hydrophilization device 40 may be stacked above or below the surface modification device 30.

[0023] A bonding device 41 is located in the second processing block G2. The bonding device 41 bonds the hydrophilized first substrate W1 and the second substrate W2 by intermolecular forces. The specific configuration of the bonding device 41 will be described later.

[0024] A transport area 60 is formed in the region enclosed by the first processing block G1, the second processing block G2, and the third processing block G3. A transport device 61 is arranged in the transport area 60. The transport device 61 has a transport arm that is movable, for example, in the vertical direction, horizontal direction, and around the vertical axis. The transport device 61 moves within the transport area 60 and transports the first substrate W1, the second substrate W2, and the polymer substrate T to predetermined devices in the first processing block G1, the second processing block G2, and the third processing block G3 adjacent to the transport area 60.

[0025] The bonding system 1 also includes a control unit 70. The control unit 70 controls the operation of the bonding system 1. This control unit 70 is, for example, a computer and includes a control unit and a memory unit (not shown). The control unit includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), input / output ports, and various circuits. The CPU of this microcomputer realizes the control described later by reading and executing a program stored in the ROM. The memory unit is realized by, for example, semiconductor memory elements such as RAM and flash memory, or storage devices such as hard disks and optical discs.

[0026] Such a program may have been recorded on a computer-readable recording medium and installed from that recording medium into the memory unit of the control unit 70. Examples of computer-readable recording media include hard disks (HDs), flexible disks (FDs), compact discs (CDs), magnetic optical discs (MOs), and memory cards.

[0027] <Overview of joining process> Next, an overview of the joining process performed by the joining device 41 will be described with reference to Figure 3. Figure 3 is a schematic diagram showing an example of how the joining area expands. Note that while a negative Miller exponent is usually indicated by placing a "-" (bar) above the number, in this specification it is indicated by placing a negative sign before the number.

[0028] As shown in Figure 3, the first substrate W1 and the second substrate W2 are single-crystal silicon wafers with a crystal orientation

[0100] perpendicular to the surface. The notches N of the first substrate W1 and the second substrate W2 are formed on the outer edges of the first substrate W1 and the second substrate W2 in the

[0011] crystal orientation. The diameters of the first substrate W1 and the second substrate W2 are, for example, 300 mm.

[0029] The bonding apparatus 41 positions the first substrate W1 and the second substrate W2 facing each other with a gap between them, and then presses down the center of the first substrate W1 to bring it into contact with the center of the second substrate W2. As a result, as shown in Figure 3, the centers of the first substrate W1 and the second substrate W2 are joined by intermolecular forces, and a bonding region A is formed in the centers of both substrates W1 and W2. Subsequently, a bonding wave is generated as the bonding region A expands from the centers outward from the edges of both substrates, and the bonding surfaces W1j and W2j of the first substrate W1 and the second substrate W2 are joined together over their entire surfaces.

[0030] The first substrate W1 and the second substrate W2 have different physical properties, such as Young's modulus and Poisson's ratio, in the 90-degree direction and the 45-degree direction. The 90-degree direction is a 90-degree periodic direction (0, 90, 180, and 270-degree directions shown in Figure 3) based on the direction from the center of the first substrate W1 toward the [0-11] crystal direction parallel to the surface of the first substrate W1. The 45-degree direction is a 90-degree periodic direction (45, 135, 225, and 315-degree directions shown in Figure 3) based on the direction from the center of the first substrate W1 toward the

[0010] crystal direction parallel to the surface of the first substrate W1.

[0031] Specifically, the Young's modulus of a single-crystal silicon wafer is highest in the 90-degree direction and lowest in the 45-degree direction. Similarly, the Poisson's ratio and shear modulus are highest in the 45-degree direction and lowest in the 90-degree direction. As a result, there is a difference in the amount of elongation of the first substrate W1 between the 90-degree and 45-degree directions. Specifically, the first substrate W1 elongates more in the 90-degree direction than in the 45-degree direction, and the difference in the amount of elongation of the first substrate W1 between the 90-degree and 45-degree directions increases towards the outer edge of the first substrate W1.

[0032] Conventionally, in the above bonding process, the first substrate W1 is fixed by a highly rigid holding portion. Specifically, the first substrate W1 is held by suction at its outer periphery by the holding portion. In this case, tensile stress due to the bonding force in bonding region A and tensile stress due to the suction holding force at the outer periphery are generated inside the first substrate W1 on the outer periphery side of bonding region A. On the other hand, the second substrate W2 is held by suction over its entire surface by the holding portion. Therefore, the first substrate W1 is more prone to radial stretching compared to the second substrate W2. Furthermore, in the above bonding process, the first substrate W1 is bonded to the second substrate W2 while curving from the center to the outer periphery. In this case, air resistance is generated on the surface of the first substrate W1 from the center to the outer periphery. This air resistance also makes the first substrate W1 prone to radial stretching.

[0033] If the first substrate W1 elongates radially compared to the second substrate W2, a misalignment will occur between the outer edges of the first substrate W1 and the second substrate W2 at the outer periphery of the polymer substrate T. This may lead to product defects and reduced productivity. Therefore, there is a need for a technology that reduces this misalignment of the outer edges and improves the bonding accuracy of the polymer substrate T. In the following explanation, the misalignment of the outer edges of the first substrate W1 and the second substrate W2 may be referred to as OVL (OVerLay).

[0034] Furthermore, as mentioned above, the first substrate W1 (and the second substrate W2) is prone to differences in the amount of elongation between the 90-degree and 45-degree directions. This anisotropy in elongation is also one of the factors that increases OVL.

[0035] In conventional bonding apparatuses, for example, a technique is known to reduce OVL by adjusting the amount of elongation at the outer periphery of the second substrate W2 by changing the shape of the outer periphery of the holding part that holds the second substrate W2. However, when adjusting the amount of elongation by physically displacing the outer periphery of the second substrate W2, there is a problem that the amount of elongation that can be controlled is relatively small, and therefore OVL is not sufficiently reduced.

[0036] Therefore, in the bonding apparatus 41 according to this embodiment, a rib located on the outer periphery of the lower surface of the second substrate W2 and a heating unit for heating the rib are provided. With this configuration, the coefficient of thermal expansion at the outer periphery of the second substrate W2 can be controlled by heating the outer periphery of the second substrate W2 via the rib. As a result, the amount of elongation at the outer periphery of the second substrate W2 can be controlled more significantly compared to conventional bonding apparatuses. Consequently, the OVL at the outer periphery of the polymerized substrate T can be reduced more effectively.

[0037] <Configuration of the joining device> Next, the configuration of the joining device 41 will be described with reference to Figures 4 to 7. Figure 4 is a schematic diagram showing the configuration of the joining device 41 according to the embodiment. As shown in Figure 4, the joining device 41 comprises a first holding part 140, a second holding part 141, and a striker 190.

[0038] The first holding portion 140 is a member that holds the first substrate W1 from above. The first holding portion 140 has a main body portion 170. The main body portion 170 is supported by a support member 180. Through holes 176 are formed in the support member 180 and the main body portion 170, penetrating vertically through the support member 180 and the main body portion 170. The position of the through holes 176 corresponds to the center of the first substrate W1 that is held by the first holding portion 140. The pressing pin 191 of the striker 190 is inserted through the through holes 176.

[0039] The striker 190 is positioned on the upper surface of the support member 180 and comprises a pressing pin 191, an actuator 192, and a linear motion mechanism 193. The pressing pin 191 is a cylindrical member extending along the vertical direction and is supported by the actuator 192.

[0040] The actuator unit 192 generates a constant pressure in a specific direction (here, vertically downward) using air supplied, for example, from an electro-pneumatic regulator (not shown). The actuator unit 192 can contact the center of the first substrate W1 with the air supplied from the electro-pneumatic regulator and control the pressing load applied to the center of the first substrate W1. Furthermore, the tip of the actuator unit 192 is able to move up and down vertically by passing through the through hole 176 using air from the electro-pneumatic regulator.

[0041] The actuator unit 192 is supported by the linear motion mechanism 193. The linear motion mechanism 193 moves the actuator unit 192 along the vertical direction, for example, by a drive unit that incorporates a motor.

[0042] The striker 190 controls the movement of the actuator 192 by the linear motion mechanism 193, and the actuator 192 controls the pressing load on the first substrate W1 by the pressing pin 191. As a result, the striker 190 presses the center of the first substrate W1, which is held by the first holding part 140, and brings it into contact with the second substrate W2.

[0043] The lower surface of the main body 170 is provided with a plurality of pins 171 that contact the upper surface (non-bonding surface W1n) of the first substrate W1. The plurality of pins 171 have, for example, a diameter of 0.1 mm to 1 mm and a height of several tens of micrometers to several hundred micrometers. The plurality of pins 171 are evenly arranged at intervals of, for example, 1 to 10 mm.

[0044] The first holding portion 140 is provided with a plurality of suction portions for adsorbing the first substrate W1 in a portion of the area where the plurality of pins 171 are provided. Specifically, the lower surface of the main body portion 170 of the first holding portion 140 is provided with an outer suction portion 301 and an inner suction portion 302 for adsorbing the first substrate W1 by vacuuming it. The outer suction portion 301 and the inner suction portion 302 have an arc-shaped suction region in a plan view. In addition, the outer suction portion 301 and the inner suction portion 302 are at the same height as the pins 171.

[0045] The outer suction portion 301 (an example of a suction port) is provided at a position opposite to the first rib 202 of the second holding portion 141, which will be described later. Specifically, the outer suction portion 301 is located directly above the first rib 202. This outer suction portion 301 is connected to a suction device (not shown), such as a vacuum pump, and uses vacuum to attract the outer periphery of the first substrate W1.

[0046] The inner suction portion 302 is positioned on the central side of the main body portion 170, closer to the center than the outer suction portion 301, and is arranged along the circumferential direction. The inner suction portion 302 is connected to a suction device (not shown), such as a vacuum pump, and attracts the region between the outer periphery and the center of the first substrate W1 by vacuuming.

[0047] In this embodiment, the first holding portion 140 has only two suction portions, an outer suction portion 301 and an inner suction portion 302. However, it is not limited to this configuration, and the first holding portion 140 may have three or more suction portions. That is, in addition to the outer suction portion 301 and the inner suction portion 302, the first holding portion 140 may have one or more additional suction portions. Such suction portions may have an arc-shaped suction region in a plan view.

[0048] Next, the configuration of the second retaining portion 141 will be described. Figure 5 is a plan view of the second retaining portion according to the embodiment, viewed from above. Figure 6 is a schematic diagram showing the configuration of the outer periphery of the second retaining portion according to the embodiment. Figure 7 is a plan view of the second retaining portion according to the embodiment, viewed from below.

[0049] The second holding portion is positioned below the first holding portion 140 and is a member that holds the second substrate W2 from below. The second holding portion 141 has a main body portion 200 having a diameter approximately the same as or larger than that of the second substrate W2. The upper surface of the main body portion 200 is a facing surface that faces the lower surface (non-bonding surface W2n) of the second substrate W2.

[0050] The upper surface of the main body 200 is provided with a plurality of pins 201 that contact the lower surface (non-bonding surface W2n) of the second substrate W2. The plurality of pins 201 have, for example, a diameter of 0.1 mm to 1 mm and a height of several tens of micrometers to several hundred micrometers. The plurality of pins 201 are evenly arranged at intervals of, for example, 1 to 10 mm.

[0051] Furthermore, the upper surface of the main body 200 is provided with a plurality of ribs that are spaced apart along the radial direction and arranged circumferentially (see Figure 5). Specifically, these plurality of ribs include a first rib 202, a second rib 203, and a plurality of inner circumferential ribs 206.

[0052] The first rib 202 is an annular member that is circumferentially arranged on the outer side of the multiple pins 201. The first rib 202 is in contact with the outer periphery of the lower surface of the second substrate W2 and conducts heat from the heating section 400 (described later) to the outer periphery of the second substrate W2.

[0053] As described above, the outer suction portion 301 of the first holding portion 140 is provided at a position opposite to the first rib 202. With this configuration, when the first substrate W1 has anisotropy in the amount of elongation in the in-plane direction, the bonding accuracy of the polymer substrate T is less likely to deteriorate. For example, in a plan view of the bonding apparatus 41, if the outer suction portion 301 is located on the inner circumference side of the first rib 202, the anisotropy in the amount of elongation of the first substrate W1 is more likely to become apparent on the outer circumference side of the outer suction portion 301. Specifically, on the outer circumference side of the outer suction portion 301, the effect of suppressing the elongation of the first substrate W1 by the suction holding force of the outer suction portion 301 is less likely to occur, so the anisotropy in the amount of elongation is more likely to become apparent. On the other hand, in this embodiment, by providing the outer suction portion 301 of the first holding portion 140 at a position opposite to the first rib 202, the radial elongation of the first substrate W1 is suppressed by the suction holding force of the outer suction portion 301, thereby reducing the deterioration of bonding accuracy of the polymer substrate T due to the anisotropy of the amount of elongation.

[0054] The second rib 203 is an annular member that is circumferentially arranged on the central side of the main body 200, closer to the center than the first rib 202, and is provided adjacent to the first rib 202. The second rib 203 is arranged concentrically with the first rib 202.

[0055] Multiple inner circumferential ribs 206 are arranged circumferentially on the central side of the main body portion 200, closer to the center than the second rib 203. The multiple inner circumferential ribs 206 are annular members having different diameters from each other. These multiple inner circumferential ribs 206 are arranged concentrically with the first rib 202 and the second rib 203. In this embodiment, an example is shown in which two inner circumferential ribs 206 are provided on the upper surface of the main body portion 200.

[0056] As shown in Figure 4, the second rib 203 and the multiple inner circumferential ribs 206 have a lower height than the multiple pins 201 and the first rib 202. That is, the second rib 203 and the multiple inner circumferential ribs 206 are formed as non-contact ribs that do not come into contact with the lower surface of the second substrate W2 supported by the multiple pins 201 and the first rib 202.

[0057] On the upper surface of the main body 200, the area inside the first rib 202 is demarcated by the first rib 202, the second rib 203, and a plurality of inner circumferential ribs 206. In this embodiment, the area inside the first rib 202 is demarcated into the area inside the inner circumferential rib 206 located on the central side of the main body (hereinafter referred to as the "first suction area") R1, the area located between the two inner circumferential ribs 206 (hereinafter referred to as the "second suction area") R2, the area located between the inner circumferential rib 206 located on the outer circumference side of the main body and the second rib 203 (hereinafter referred to as the "third suction area"), and the area located between the second rib 203 and the first rib 202 (hereinafter referred to as the "fourth suction area").

[0058] The main body 200 has a suction port 204. The suction port 204 is provided in the first suction region R1. The suction port 204 is connected to a suction device 205 via a suction tube 204a. The suction device 205 is, for example, a vacuum pump.

[0059] The second holding section 141 evacuates the suction regions R1 to R4 from the suction port 204, thereby reducing the pressure in the suction regions R1 to R4. As described above, the height of the second rib 203 and the multiple inner circumferential ribs 206 is set lower than the height of the multiple pins 201 and the first rib 202. As a result, a gap is formed between the second rib 203 and the multiple inner circumferential ribs 206 and the second substrate W2. This allows the pressure in the suction regions R1 to R4 to be reduced by suction from the suction port 204.

[0060] When the suction regions R1 to R4 are depressurized, the atmosphere outside the suction regions R1 to R4 is atmospheric pressure, so the second substrate W2 is pushed towards the suction regions R1 to R4 by the amount of the depressurization due to the atmospheric pressure. As a result, the second substrate W2 is adsorbed and held by the second holding part 141. Furthermore, according to the second holding part 141 of this embodiment, the suction regions R1 to R4 can be depressurized in stages. This makes it possible to adjust the holding force of the second substrate W2 in stages from the center to the outer periphery of the second substrate W2.

[0061] In this embodiment, an example is shown in which suction regions R1, R2, R3, and R4 are vacuumed using a single suction port 204. However, the configuration is not limited to this, and suction regions R1, R2, R3, and R4 may each be vacuumed individually. That is, the second holding unit 141 may have a configuration having multiple suction ports corresponding to each suction region.

[0062] As shown in Figure 6, the second holding portion 141 has a heating portion 400 for heating the first rib 202. Specifically, the heating portion 400 is provided circumferentially on the outer periphery of the main body portion 200 so as to be located below the first rib 202 (see Figure 7). In this embodiment, the heating portion 400 is provided inside the main body portion 200. The heat generated in the heating portion 400 is conducted to the outer periphery of the second substrate W2 via the first rib 202. The heating portion 400 may also be provided, for example, on the lower surface of the main body portion 200.

[0063] The heating element 400 is, for example, a Peltier element. The heating element 400 is not limited to a Peltier element; it may also be, for example, an electric heating wire.

[0064] With this configuration, the coefficient of thermal expansion at the outer periphery of the second substrate W2 can be controlled by adjusting the heating temperature of the outer periphery of the second substrate W2 via the first rib 202. Specifically, when the outer periphery of the second substrate W2 is heated, the outer periphery of the second substrate expands due to thermal expansion. As a result, for example, in the bonding of the first substrate W1 and the second substrate W2, even if the first substrate W1 expands radially, the OVL of the polymer substrate T can be reduced by expanding the outer periphery of the second substrate W2 in accordance with this expansion. The amount of expansion of the outer periphery of the second substrate W2 can be controlled by adjusting the heating temperature of the heating section 400.

[0065] Furthermore, with this configuration, the amount of elongation at the outer periphery of the second substrate W2 can be adjusted more significantly compared to conventional bonding devices, which adjust the amount of elongation by physically displacing the outer periphery of the second substrate W2. For example, when the thickness of the first substrate W1 decreases, the first substrate W1 tends to stretch more in the radial direction. For this reason, with conventional bonding devices, it was difficult to reduce OVL when the thickness of the first substrate W1 was relatively thin. On the other hand, with this embodiment, even when the thickness of the first substrate W1 is relatively thin, the amount of elongation at the outer periphery of the second substrate W2 can be adjusted to a large extent, thus effectively reducing OVL.

[0066] Furthermore, this configuration offers greater versatility for the bonding apparatus 41 compared to a bonding apparatus that adjusts the amount of elongation by changing the shape of the outer periphery of the holding part that holds the second substrate W2. For example, in a conventional bonding apparatus that changes the shape of the holding part, it is necessary to adjust the amount of shape change of the holding part when changing the wafer type. However, it is difficult to optimize and adjust this amount of shape change for each wafer type, so it was necessary to prepare a large number of holding parts according to the wafer type. On the other hand, according to this embodiment, since OVL is reduced by temperature control of the second substrate W2, the same second holding part 141 can be used even when the wafer type changes.

[0067] As shown in Figure 7, in this embodiment, the heating section 400 is provided below the first rib 202, aligned along the radial direction of the main body 200, and includes two heating sections whose temperatures can be individually adjusted. Specifically, the heating section 400 includes a first heating section 410 located on the inner circumference side of the main body 200 and a second heating section 420 located on the outer circumference side of the main body 200. The first heating section 410 and the second heating section 420, which is radially adjacent to the first heating section 410, correspond to an example of a radial heating section. The first heating section 410 and the second heating section 420 may be Peltier elements or heating wires arranged in regions that divide the outer circumference of the main body 200 into two radial sections. In this embodiment, an example is shown in which the heating section 400 includes two heating sections along the radial direction, but the configuration is not limited to this, and the heating section 400 may include three or more heating sections along the radial direction. In such a case, each heating element may be arranged in a region obtained by dividing the outer periphery of the main body 200 in the radial direction.

[0068] As described above, the difference in the degree of strain between the first substrate W1 and the second substrate W2 increases toward the outer edges of the first substrate W1 and the second substrate W2. According to this embodiment, since the coefficient of thermal expansion of the second substrate W2 in the outer peripheral portion can be finely controlled along the radial direction, the difference in the degree of strain between the first substrate W1 and the second substrate W2 can be more preferably reduced compared to the case where the second holding portion 141 does not have the first heating portion 410 and the second heating portion 420. Specifically, by making the heating temperature of the second heating portion 420 located on the outer peripheral side higher than the heating temperature of the first heating portion 410 located on the inner peripheral side, the difference in the degree of strain can be preferably reduced. As a result, the OVL of the polymer substrate T can be more preferably reduced.

[0069] Furthermore, as shown in Figure 7, in this embodiment, the first heating section 410 is arranged circumferentially below the first rib 202 and includes a plurality of individually temperature-adjustable individual heating sections (an example of circumferential heating sections). Specifically, the first heating section 410 has four first individual heating sections 410A arranged at 90-degree intervals with respect to the 0-degree direction, when the direction toward the [0-11] crystal direction of the first substrate W1 is defined as 0 degrees, and four second individual heating sections 410B arranged at 90-degree intervals with respect to the 45-degree direction. The first individual heating sections 410A and the second individual heating sections 410B may be Peltier elements or heating wires provided in correspondence to each of the eight regions obtained by dividing the outer periphery of the main body 200 in the circumferential direction (see Figure 7).

[0070] Similarly, in this embodiment, the second heating section 420 also includes a plurality of individual heating sections (an example of circumferential heating sections) arranged along the circumferential direction and individually temperature-adjustable. The second heating section 420 has four first individual heating sections 420A arranged at 90-degree intervals with respect to the 0-degree direction, when the direction toward the [0-11] crystal direction of the first substrate W1 is defined as 0 degrees, and four second individual heating sections 420B arranged at 90-degree intervals with respect to the 45-degree direction. The first individual heating sections 420A and the second individual heating sections 420B may be Peltier elements or heating wires provided in correspondence to each of the eight regions obtained by dividing the outer periphery of the main body 200 in the circumferential direction (see Figure 7).

[0071] With this configuration, for example, the thermal expansion coefficient of the second substrate W2 in the outer periphery can be finely controlled along the circumferential direction. As described above, the second substrate W2 (and the first substrate W1) has different amounts of expansion in the 90-degree direction and the 45-degree direction. Specifically, the amount of expansion in the 90-degree direction is greater than the amount of expansion in the 45-degree direction. According to this embodiment, by setting the heating temperature of the second individual heating section 410B (second individual heating section 420B) higher than the heating temperature of the first individual heating section 410A (first individual heating section 420A), the amount of expansion of the second substrate W2 in the 45-degree direction can be adjusted to be greater than the amount of expansion of the second substrate W2 in the 90-degree direction. Therefore, even if the second substrate W2 (and the first substrate W1) has anisotropy in the amount of expansion in the in-plane direction, the OVL of the polymerized substrate T can be suitably reduced.

[0072] In the main body 200, an insulating space 207 is provided between the first rib 202 and the second rib 203. With this configuration, heat from the first rib 202 is less likely to be transferred to the central side of the second substrate W2. As a result, when the second substrate W2 is heated by the heating unit 400 via the first rib 202, the outer periphery of the second substrate W2 can be accurately heated. Furthermore, the accuracy of temperature control of the second substrate W2 by heating can be improved. Therefore, the OVL of the polymer substrate T can be reduced with high accuracy.

[0073] Although not shown in the diagram here, the bonding apparatus 41 includes a transition, an inversion mechanism, and a position adjustment mechanism prior to the first holding section 140 and the second holding section 141 shown in Figure 4. The transition temporarily places the first substrate W1, the second substrate W2, and the bonding substrate T on it. The position adjustment mechanism adjusts the horizontal orientation of the first substrate W1 and the second substrate W2. The inversion mechanism inverts the front and back sides of the first substrate W1.

[0074] <Specific operation of the joining system> Next, the specific operation of the joining system 1 will be described with reference to Figure 8. Figure 8 is a flowchart showing the procedure of processing performed by the joining system 1 according to this embodiment. The various processes shown in Figure 8 are executed based on control by the control unit 70.

[0075] First, cassette C1 containing multiple first circuit boards W1, cassette C2 containing multiple second circuit boards W2, and an empty cassette C3 are placed on a designated mounting plate 11 at the loading / unloading station 2. Then, the transport device 22 removes the first circuit boards W1 from cassette C1 and transports them to the transition device located in the third processing block G3.

[0076] Next, the first substrate W1 is transported by the transport device 61 to the surface modification device 30 of the first processing block G1. In the surface modification device 30, under a predetermined reduced pressure atmosphere, oxygen gas, which is the processing gas, is excited, plasma-generated, and ionized. These oxygen ions are irradiated onto the bonding surface of the first substrate W1, and the bonding surface is plasma-treated. As a result, the bonding surface of the first substrate W1 is modified (step S101). Note that the processing gas is not limited to oxygen gas, but may also be nitrogen gas, argon gas, helium gas, etc.

[0077] Next, the first substrate W1 is transported by the transport device 61 to the surface hydrophilization device 40 of the second processing block G1. In the surface hydrophilization device 40, pure water is supplied onto the first substrate W1 while it is rotated, which is held in a spin chuck. This hydrophilizes the bonding surface of the first substrate W1. In addition, the bonding surface of the first substrate W1 is cleaned by the pure water (step S102).

[0078] Next, the first substrate W1 is transported by the transport device 61 to the bonding device 41 of the second processing block G2. The first substrate W1, once loaded into the bonding device 41, is transported via a transition to the position adjustment mechanism, where its horizontal orientation is adjusted (step S103).

[0079] Subsequently, the first substrate W1 is transferred from the position adjustment mechanism to the inversion mechanism, and the inversion mechanism inverts the front and back surfaces of the first substrate W1 (step S104). Specifically, the bonding surface W1j of the first substrate W1 is oriented downwards.

[0080] Subsequently, the first substrate W1 is transferred from the reversal mechanism to the first holding unit 140, and the first substrate W1 is held by the first holding unit 140 through suction (step S105).

[0081] The processing of the second substrate W2 is performed in overlap with the processing of the first substrate W1 in steps S101 to S105. First, the transport device 22 removes the second substrate W2 from the cassette C2 and transports it to the transition device located in the third processing block G3.

[0082] Next, the second substrate W2 is transported by the transport device 61 to the surface modification device 30, where the bonding surface W2j of the second substrate W2 is modified (step S106). After that, the second substrate W2 is transported by the transport device 61 to the surface hydrophilization device 40, where the bonding surface W2j of the second substrate W2 is hydrophilized and the bonding surface is cleaned (step S107).

[0083] Subsequently, the second substrate W2 is transported to the bonding device 41 by the transport device 61. The second substrate W2, once loaded into the bonding device 41, is transported to the position adjustment mechanism via a transition. The position adjustment mechanism then adjusts the horizontal orientation of the second substrate W2 (step S108).

[0084] Subsequently, the second substrate W2 is transported to the second holding unit 141 and held by suction in the second holding unit 141 with the notch portion facing a predetermined direction (step S109). Specifically, the second holding unit 141 operates the suction device 205 to evacuate the second substrate W2 from the suction port 204 in the suction region R1. Here, each of the suction regions R1 to R4 is partitioned by the first rib 202, the second rib 203, and multiple inner circumferential ribs 206, respectively. Therefore, when evacuating from the suction port 204 begins, evacuating is performed in the order of suction regions R1, R2, R3, and R4. The negative pressure in the suction regions R1 to R4 approaches atmospheric pressure in the order of suction regions R1, R2, R3, and R4. As a result, the second substrate W2 is held by suction in the suction regions R1 to R4.

[0085] Next, the horizontal position of the first substrate W1 held by the first holding part 140 and the second substrate W2 held by the second holding part 141 is adjusted (step S110).

[0086] Next, the vertical position of the first substrate W1 held by the first holding part 140 and the second substrate W2 held by the second holding part 141 is adjusted (step S111). Specifically, the second substrate W2 is brought closer to the first substrate W1 by moving the second holding part 141 vertically upward using a moving mechanism (not shown) that moves the second holding part 141 vertically.

[0087] Next, the temperature of the second substrate W2 is adjusted (step S112). Specifically, the temperature of the outer periphery of the second substrate W2 is adjusted by adjusting the temperature of the heating section 400 that heats the first rib 202. More specifically, the temperature of the outer periphery of the second substrate W2 is adjusted by adjusting the temperatures of the first individual heating section 410A and the second individual heating section 410B of the first heating section 410, and the temperatures of the first individual heating section 420A and the second individual heating section 420B of the second heating section 420. The control unit 70 adjusts the temperature of the heating section 400, for example, based on a preset temperature recipe.

[0088] Subsequently, while maintaining the second substrate W2 at the adjusted temperature, the first substrate W1 and the second substrate W2 are joined (step S113). Specifically, the center of the first substrate W1 comes into contact with the center of the second substrate W2, and when the centers of the first substrate W1 and the second substrate W2 are pressed together with a predetermined force by the striker 190, bonding begins between the pressed centers of the first substrate W1 and the second substrate W2. That is, since the bonding surface W1j of the first substrate W1 and the bonding surface W2j of the second substrate W2 have been modified in steps S101 and S109, van der Waals forces (intermolecular forces) are first generated between the bonding surfaces W1j and W2j, and these bonding surfaces W1j and W2j are joined together. Furthermore, since the bonding surface W1j of the first substrate W1 and the bonding surface W2j of the second substrate W2 are hydrophilized in steps S102 and S110, the hydrophilic groups between the bonding surfaces W1j and W2j form hydrogen bonds, and the bonding surfaces W1j and W2j are firmly joined together. In this way, a bonding region A (see Figure 2) is formed. Subsequently, a bonding wave is generated between the first substrate W1 and the second substrate W2, in which the bonding region expands from the center of the first substrate W1 and the second substrate W2 toward the outer periphery. Then, the bonding surface W1j of the first substrate W1 and the bonding surface W2j of the second substrate W2 come into full contact, and a polymerized substrate T is formed.

[0089] In this embodiment, by maintaining the second substrate W2 at the adjusted temperature in step S113, the bonding process is performed with the second substrate W2 radially stretched in the outer periphery of the second substrate W2, specifically in the heating region of the first rib 202 on the second substrate W2. As a result, the first substrate W1 and the second substrate W2 are bonded together such that the position of the outer edge of the second substrate W2 coincides with the position of the outer edge of the first substrate W1.

[0090] Subsequently, the pressure from the striker 190 is released, and the suction holding of the second substrate W2 by the second holding unit 141 is released. Then, the polymerized substrate T is discharged from the bonding device 41 by the transport device 61. In this way, the series of bonding processes is completed.

[0091] In this embodiment, an example is shown where the vertical position adjustment in step S111 is performed after the horizontal position adjustment in step S110. However, the horizontal position adjustment may be performed after the vertical position adjustment.

[0092] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0093] Furthermore, this technology can also be configured as follows. (1) A first holding part that holds the first substrate from above, A second holding portion is positioned below the first holding portion and holds the second substrate, which is bonded to the first substrate, from below. A striker presses the center of the first substrate held in the first holding part from above. It has, The second retaining part is, The main body portion facing the lower surface of the second substrate, The main body is provided with a first rib that is circumferentially located and in contact with the outer peripheral portion of the lower surface of the second substrate, A second rib is provided circumferentially on the central side of the main body portion, A heating section for heating the first rib, The thermal insulation space located between the first rib and the second rib and A joining device having the following features. (2) The joining apparatus according to (1), wherein the heating section is arranged circumferentially so as to be located below the first rib and includes a plurality of circumferential heating sections whose temperature can be individually adjusted. (3) The plurality of circumferential heating units are, Four first individual heating units, Four second individual heating units and Includes, The first substrate is a single-crystal silicon wafer with the crystal direction perpendicular to the surface being

[0100] . The bonding apparatus according to (2), wherein when the direction from the center of the first substrate toward the [0-11] crystal direction parallel to the surface of the first substrate is defined as 0 degrees, the four first individual heating units are arranged at 90-degree intervals with respect to the 0-degree direction, and the four second individual heating units are arranged at 90-degree intervals with respect to the 45-degree direction. (4) The joining apparatus according to any one of (1) to (3), wherein the heating section is provided below the first rib and arranged along the radial direction of the main body, and includes a plurality of radial heating sections whose temperature can be individually adjusted. (5) The main body portion has a plurality of ribs that are spaced apart along the radial direction and are provided circumferentially in a plan view. The plurality of ribs include the first rib and the second rib, The second rib is provided adjacent to the first rib, and is a joining device according to any one of (1) to (4) above. (6) The first holding portion has an adsorption port for adsorbing and holding the outer periphery of the first substrate, The joining device according to any one of (1) to (5), wherein the suction port is provided at a position opposite to the first rib of the second holding portion. (7) A bonding method for joining a first substrate and a second substrate, A step of holding the first substrate using a first holding part that holds the first substrate from above, A step of holding the second substrate using a second holding part that holds the second substrate from below, A step of bringing the first substrate into contact with the second substrate using a striker that presses the center of the first substrate from above. Includes, The second retaining part is, The main body portion facing the lower surface of the second substrate, The main body is provided with a first rib that is circumferentially located and in contact with the outer peripheral portion of the lower surface of the second substrate, A second rib is provided circumferentially on the central side of the main body portion, A heating section for heating the first rib, The thermal insulation space located between the first rib and the second rib and It has, A joining method further comprising the step of heating the first rib with the heating unit after the contact step. [Explanation of symbols]

[0094] 1. Joining System 41 Bonding equipment 70 Control Unit 140 1st holding part 141 Second holding part 170,200 Main unit 190 Striker 202 First Rib 203 Second Rib 206 Inner Rib 207 Insulated Space 301 Outside suction part 400 Heating section 410 1st heating section 420 2nd heating section 410A, 420A First Individual Heating Section 410B,420B 2nd individual heating section A joining area W1 First Circuit Board W2 Second Board T Polymerization substrate

Claims

1. A first holding part that holds the first substrate from above, A second holding portion is positioned below the first holding portion and holds the second substrate, which is bonded to the first substrate, from below. A striker that presses the center of the first substrate held in the first holding part from above, It has, The second retaining part is, The main body portion facing the lower surface of the second substrate, The main body is provided with a first rib that is circumferentially located and in contact with the outer peripheral surface of the lower surface of the second substrate, A second rib is provided circumferentially on the central side of the main body portion, A heating section for heating the first rib, The insulating space located between the first rib and the second rib and A joining device having the following features.

2. The bonding apparatus according to claim 1, wherein the heating section is arranged circumferentially so as to be located below the first rib and includes a plurality of circumferential heating sections whose temperature can be individually adjusted.

3. The plurality of circumferential heating units are, Four first individual heating units, Four second individual heating units and Includes, The first substrate is a single-crystal silicon wafer with the crystal direction perpendicular to the surface being the [100] crystal direction. The bonding apparatus according to claim 2, wherein when the direction from the center of the first substrate toward the [0-11] crystal direction parallel to the surface of the first substrate is defined as 0 degrees, the four first individual heating units are arranged at 90-degree intervals with respect to the 0-degree direction, and the four second individual heating units are arranged at 90-degree intervals with respect to the 45-degree direction.

4. The joining apparatus according to claim 1, wherein the heating section is provided below the first rib and arranged along the radial direction of the main body, and includes a plurality of radial heating sections whose temperature can be individually adjusted.

5. The main body portion has a plurality of ribs that are spaced apart along the radial direction and are provided circumferentially in a plan view. The plurality of ribs include the first rib and the second rib, The joining device according to claim 1, wherein the second rib is provided adjacent to the first rib.

6. The first holding portion has an adsorption port for adsorbing and holding the outer periphery of the first substrate, The joining device according to claim 1, wherein the suction port is provided at a position opposite to the first rib of the second holding portion.

7. A bonding method for joining a first substrate and a second substrate, A step of holding the first substrate using a first holding part that holds the first substrate from above, A step of holding the second substrate using a second holding part that holds the second substrate from below, A step of bringing the first substrate into contact with the second substrate using a striker that presses the center of the first substrate from above. Includes, The second retaining part is, The main body portion facing the lower surface of the second substrate, The main body is provided with a first rib that is circumferentially located and in contact with the outer peripheral surface of the lower surface of the second substrate, A second rib is provided circumferentially on the central side of the main body portion, A heating section for heating the first rib, The insulating space located between the first rib and the second rib and It has, A joining method further comprising the step of heating the first rib with the heating unit after the contact step.

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