Substrate treatment device and substrate treatment method

Abstract

This substrate treatment device comprises: a holding part in which a vacuum-chucking surface for vacuum-chucking a substrate is provided with a circular central region and an annular outer-side region disposed farther outward than the central region; a vacuum-chucking pressure generation unit that generates vacuum-chucking force individually in the central region, an outer-side first zone that is set to one site in the circumferential direction of the outer-side region, and an outer-side second zone that is set to a site different from that of the first zone in the circumferential direction of the outer-side region; and a control unit that controls the vacuum-chucking pressure generation unit. The control unit selects an outer-side / central pattern in which vacuum-chucking force is generated in the outer-side first zone and the central region in the stated order, or a central / outer-side pattern in which vacuum-chucking force is generated in the central region and the outer-side first zone in the stated order, in accordance with the state of curvature of the substrate.

Description

Substrate processing apparatus and substrate processing method

[0001] The present disclosure relates to a substrate processing apparatus and a substrate processing method.

[0002] Patent Document 1 discloses a bonding device that includes an upper chuck that adsorbs the upper substrate from above and a lower chuck that adsorbs the lower substrate from below, and that bonds two substrates face to face. In bonding the substrates, the bonding device presses down the center of the substrate on the upper chuck to bring it into contact with the center of the substrate on the lower chuck, bonds the centers of the two substrates together by intermolecular forces, and expands the bonding area from the center to the periphery.

[0003] In a substrate processing apparatus that holds a substrate by suction as described above, if the substrate is simply suctioned to the chuck, there is a possibility that the substrate may be processed in a state where residual stress is large due to warping or other reasons in the substrate.

[0004] Japanese Patent Application Laid-Open No. 2015-095579

[0005] The present disclosure provides a technique that can improve the distribution of residual stress in a substrate and properly adsorb the substrate.

[0006] According to one aspect of the present disclosure, there is provided a substrate processing apparatus including: a holder having an adsorption surface that adsorbs a substrate, the adsorption surface having a circular central region and an annular outer region located outside the central region; an adsorption pressure generating unit that generates adsorption pressures individually in the central region, an outer first zone set at a circumferential position of the outer region, and an outer second zone set at a circumferential position of the outer region different from the outer first zone; and a control unit that controls the adsorption pressure generating unit, wherein the control unit selects, depending on a warpage state of the substrate, an outer central pattern that generates adsorption pressures in the outer first zone and then the central region, or a central outer pattern that generates adsorption pressures in the central region and then the outer first zone.

[0007] According to one aspect, the distribution of residual stress in the substrate can be improved to properly adsorb the substrate.

[0008] 9(A) is a side view showing an example of an operation in step S112 of FIG. 8. FIG. 9(B) is a side view showing an operation subsequent to FIG. 9(A). FIG. 9(C) is a side view showing an operation subsequent to FIG. 9(B). FIG. 10(A) is a cross-sectional view showing an example of an operation in step S113 of FIG. 8. FIG. 10(B) is a cross-sectional view showing an example of an operation in step S114 of FIG. 8. FIG. 10(C) is a cross-sectional view showing an operation subsequent to FIG. 10(B). FIG. 12(A) is a plan view showing an example of an adsorption surface of a lower chuck. FIG. 12(A) is a perspective view showing an example of warping of a lower wafer. FIG. 12(B) is an explanatory diagram showing the relationship between the suction surface and the lower wafer in the Y-axis direction. FIG. 12(C) is an explanatory diagram showing the relationship between the suction surface and the lower wafer in the X-axis direction. FIG. 14(A) is an explanatory diagram showing the relationship between the warpage of the lower wafer in the X-axis direction and the Y-axis direction. FIG. 14(B) is a plan view showing an example of the suction operation of the lower wafer. FIG. 14(C) is a plan view showing the operation following FIG. 14(B). FIG. 14(D) is a plan view showing the operation following FIG. 14(C). FIG. 14(E) is a plan view showing the operation following FIG. 14(D). FIG. 14(F) is a plan view showing the operation following FIG. 14(E). A table showing an example of the suction operation depending on the warpage state of the lower wafer. FIG. 14 is a side view of a bonding module according to a second embodiment. FIG. 14 is an explanatory diagram showing the relationship between the warpage of the lower wafer in the X-axis direction and the Y-axis direction and the curved surface of the suction surface.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] A bonding apparatus 1 shown in FIGS. 1 and 2 will be described as a representative example of the substrate processing apparatus of the present disclosure. The substrate processing apparatus of the present disclosure is not limited to the bonding apparatus 1, but may be any apparatus that includes a holder for holding a substrate and processes the substrate held by the holder. Examples of other substrate processing apparatus include an exposure apparatus and a temperature adjustment apparatus. An exposure apparatus is an apparatus that holds a substrate by a holder and transfers a mask pattern onto the substrate. A temperature adjustment apparatus is an apparatus that holds a substrate by a holder and adjusts the temperature of the substrate.

[0011] 3, the bonding apparatus 1 bonds a first substrate W1 and a second substrate W2 to produce a bonded substrate T. At least one of the first substrate W1 and the second substrate W2 is a semiconductor substrate, such as a silicon wafer or a compound semiconductor wafer, on which multiple electronic circuits are formed. One of the first substrate W1 and the second substrate W2 may be a bare wafer on which no electronic circuits are formed. The compound semiconductor wafer is not particularly limited, but may be, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer.

[0012] The first substrate W1 and the second substrate W2 are formed as circular plates of approximately the same shape (same diameter). The bonding apparatus 1 bonds the first substrate W1 and the second substrate W2 by placing the second substrate W2 on the negative Z-axis side (vertically below) of the first substrate W1. Therefore, hereinafter, the first substrate W1 may be referred to as the "upper wafer W1," the second substrate W2 as the "lower wafer W2," and the bonded substrate T as the "bonded wafer T." Furthermore, hereinafter, the surface of the upper wafer W1 that is bonded to the lower wafer W2 will be referred to as the "bonding surface W1j," and the surface opposite the bonding surface W1j will be referred to as the "non-bonding surface W1n." Furthermore, the surface of the lower wafer W2 that is bonded to the upper wafer W1 will be referred to as the "bonding surface W2j," and the surface opposite the bonding surface W2j will be referred to as the "non-bonding surface W2n."

[0013] 1, the bonding apparatus 1 includes, in order in the positive direction of the X-axis, a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are integrally connected.

[0014] 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. Each mounting plate 11 is loaded with a cassette CS1, CS2, or CS3, which accommodates a plurality of substrates (e.g., 25 substrates) in a horizontal position. The cassette CS1 accommodates the upper wafer W1, the cassette CS2 accommodates the lower wafer W2, and the cassette CS3 accommodates the bonded wafer T. In the cassettes CS1 and CS2, the upper wafer W1 and the lower wafer W2 are accommodated with their respective bonding surfaces W1j and W2j facing upward and aligned in the same direction.

[0015] The transfer region 20 is disposed adjacent to the mounting table 10 on the positive side of the X axis, and includes a transfer path 21 extending in the Y axis direction, and a transfer device 22 movable along the transfer path 21. The transfer device 22 is movable also in the X axis direction and rotatable about the Z axis, and transfers the upper wafer W1, the lower wafer W2, and the bonded wafer T between the cassettes CS1 to CS3 placed on the mounting table 10 and a third processing block PB3 of the processing station 3, which will be described later.

[0016] The processing station 3 includes, for example, three processing blocks PB1, PB2, and PB3. The first processing block PB1 is provided on the rear side of the processing station 3 (the positive Y-axis side in FIG. 1 ). The second processing block PB2 is provided on the front side of the processing station 3 (the negative Y-axis side in FIG. 1 ). The third processing block PB3 is provided on the load / unload station 2 side of the processing station 3 (the negative X-axis side in FIG. 1 ).

[0017] Furthermore, processing station 3 includes a transfer region 60 having a transfer device 61 in an area surrounded by first processing block PB1 to third processing block PB3. For example, transfer device 61 has a transfer arm that is movable vertically, horizontally, and around a vertical axis. Transfer device 61 moves within transfer region 60 to transfer upper wafer W1, lower wafer W2, and bonded wafer T to devices in first processing block PB1, second processing block PB2, and third processing block PB3 adjacent to transfer region 60.

[0018] The first processing block PB1 includes, for example, a surface modification device 33 and a surface hydrophilization device 34. The surface modification device 33 modifies the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2. The surface hydrophilization device 34 hydrophilizes the modified bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2.

[0019] For example, the surface modification device 33 may modify the SiO ２ This breaks the bond between the upper wafer W1 and the lower wafer W2, forming dangling bonds of Si, which enables subsequent hydrophilization. In the surface modification device 33, for example, oxygen gas, which is a processing gas, is excited to be turned into plasma and ionized in a reduced pressure atmosphere. The oxygen ions are then irradiated onto the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2, thereby subjecting the bonding surfaces W1j and W2j to plasma processing and modification. The processing gas is not limited to oxygen gas, and may be nitrogen gas or the like.

[0020] The surface hydrophilization device 34 hydrophilizes the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 using a hydrophilization treatment liquid such as pure water. The surface hydrophilization device 34 also serves to clean the bonding surfaces W1j and W2j. In the surface hydrophilization device 34, pure water is supplied onto the upper wafer W1 or the lower wafer W2 while rotating the upper wafer W1 or the lower wafer W2 held by, for example, a spin chuck. As a result, the pure water diffuses over the bonding surfaces W1j and W2j, attaching OH groups to the dangling Si bonds and hydrophilizing the bonding surfaces W1j and W2j.

[0021] 2 , the second processing block PB2 includes, for example, a bonding module 41, a first temperature adjustment device 42, and a second temperature adjustment device 43. The bonding module 41 bonds a hydrophilized upper wafer W1 and a lower wafer W2 to produce a bonded wafer T. The first temperature adjustment device 42 adjusts the temperature distribution of the upper wafer W1 before producing the bonded wafer T. The second temperature adjustment device 43 adjusts the temperature distribution of the lower wafer W2 before producing the bonded wafer T. In this embodiment, the first temperature adjustment device 42 and the second temperature adjustment device 43 are provided separately from the bonding module 41, but they may also be provided as part of the bonding module 41.

[0022] The third processing block PB3 includes, for example, a first position adjustment device 51, a second position adjustment device 52, and transition devices 53 and 54, arranged in this order from top to bottom. The locations of the devices in the third processing block PB3 are not limited to those shown in FIG. 2 . The first position adjustment device 51 adjusts the horizontal orientation of the upper wafer W1 and also turns the upper wafer W1 upside down so that the bonding surface W1j of the upper wafer W1 faces downward. The second position adjustment device 52 adjusts the horizontal orientation of the lower wafer W2. The transition device 53 temporarily places the upper wafer W1 thereon. The transition device 54 temporarily places the lower wafer W2 and the bonded wafer T thereon.

[0023] Returning to Fig. 1 , the bonding apparatus 1 includes a control device (control unit) 90 that controls each component. The control device 90 is a control computer having one or more processors 91, a memory 92, an input / output interface (not shown), and an electronic circuit. The one or more processors 91 are one or a combination of a CPU, an ASIC, an FPGA, a circuit made up of a plurality of discrete semiconductors, and the like, and executes and processes a program stored in the memory 92. The memory 92 includes a non-volatile memory and a volatile memory, and forms a storage unit of the control device 90.

[0024] Next, the joining method of this embodiment will be described with reference to Fig. 4. Steps S101 to S109 shown in Fig. 4 are performed under the control of the control device 90.

[0025] In the bonding method, an operator or a transport robot (not shown) places a cassette CS1 containing multiple upper wafers W1, a cassette CS2 containing multiple lower wafers W2, and an empty cassette CS3 on the loading / unloading station 2's loading table 10.

[0026] The bonding apparatus 1 uses the transfer device 22 to remove the upper wafer W1 from the cassette CS1 and transfer it to the transition device 53 in the third processing block PB3 of the processing station 3. Thereafter, the bonding apparatus 1 uses the transfer device 61 to remove the upper wafer W1 from the transition device 53 and transfer it to the surface modification device 33 in the first processing block PB1.

[0027] Next, the bonding apparatus 1 modifies the bonding surface W1j of the upper wafer W1 using the surface modification device 33 (step S101). The surface modification device 33 modifies the bonding surface W1j with the bonding surface W1j facing upward. Thereafter, the transfer device 61 removes the upper wafer W1 from the surface modification device 33 and transfers it to the surface hydrophilization device 34.

[0028] Then, the bonding apparatus 1 causes the surface hydrophilization device 34 to hydrophilize the bonding surface W1j of the upper wafer W1 (step S102). The surface hydrophilization device 34 hydrophilizes the bonding surface W1j with the bonding surface W1j facing upward. Thereafter, the transfer device 61 removes the upper wafer W1 from the surface hydrophilization device 34 and transfers it to the first position adjustment device 51 in the third processing block PB3.

[0029] The bonding apparatus 1 adjusts the horizontal orientation of the upper wafer W1 using the first position adjustment device 51 and turns the upper wafer W1 upside down (step S103). As a result, the notch of the upper wafer W1 is oriented in a predetermined direction and the bonding surface W1j of the upper wafer W1 faces downward. Thereafter, the transfer device 61 removes the upper wafer W1 from the first position adjustment device 51 and transfers it to the first temperature adjustment device 42 in the second processing block PB2.

[0030] The bonding apparatus 1 adjusts the temperature of the upper wafer W1 using the first temperature adjustment device 42 (step S104). The temperature adjustment of the upper wafer W1 is performed with the bonding surface W1j of the upper wafer W1 facing downward. Thereafter, the transfer device 61 removes the upper wafer W1 from the first temperature adjustment device 42 and transfers it to the bonding module 41.

[0031] In parallel with the above-described processing of the upper wafer W1, the bonding apparatus 1 performs processing of the lower wafer W2. First, the bonding apparatus 1 causes the transfer device 22 to remove the lower wafer W2 from the cassette CS2 and transfer it to the transition device 54 in the third processing block PB3 of the processing station 3. Thereafter, the transfer device 61 removes the lower wafer W2 from the transition device 54 and transfers it to the surface modification device 33 in the first processing block PB1.

[0032] The bonding apparatus 1 modifies the bonding surface W2j of the lower wafer W2 using the surface modification device 33 (step S105). The surface modification device 33 modifies the bonding surface W2j with the bonding surface W2j facing upward. Thereafter, the transfer device 61 removes the lower wafer W2 from the surface modification device 33 and transfers it to the surface hydrophilization device 34.

[0033] The bonding apparatus 1 hydrophilizes the bonding surface W2j of the lower wafer W2 using the surface hydrophilization device 34 (step S106). The surface hydrophilization device 34 hydrophilizes the bonding surface W2j with the bonding surface W2j facing upward. Thereafter, the transfer device 61 removes the lower wafer W2 from the surface hydrophilization device 34 and transfers it to the second position adjustment device 52 in the third processing block PB3.

[0034] The bonding apparatus 1 adjusts the horizontal orientation of the lower wafer W2 using the second position adjustment device 52 (step S107). This orients the notch of the lower wafer W2 in a predetermined direction. Thereafter, the transfer device 61 removes the lower wafer W2 from the second position adjustment device 52 and transfers it to the second temperature adjustment device 43 in the second processing block PB2.

[0035] The bonding apparatus 1 adjusts the temperature of the lower wafer W2 by the second temperature adjustment device 43 (step S108). The temperature adjustment of the lower wafer W2 is performed with the bonding surface W2j of the lower wafer W2 facing upward. Thereafter, the transfer device 61 removes the lower wafer W2 from the second temperature adjustment device 43 and transfers it to the bonding module 41.

[0036] Then, in the bonding module 41, the bonding apparatus 1 bonds the upper wafer W1 and the lower wafer W2 to produce a bonded wafer T (step S109). After producing the bonded wafer T, the transfer device 61 removes the bonded wafer T from the bonding module 41 and transfers it to the transition device 54 in the third process block PB3.

[0037] Finally, in the bonding apparatus 1, the transfer device 22 removes the bonded wafer T from the transition device 54 and transfers it to the cassette CS3 on the mounting table 10. This completes the series of processes.

[0038] 5 to 7, an example of a bonding module 41 according to the first embodiment will be described. As shown in Fig. 5, the bonding module 41 has a processing vessel 210 whose interior can be sealed. A loading / unloading port 211 is formed on the side of the processing vessel 210 on the transfer region 60 side, and the loading / unloading port 211 is provided with an opening / closing shutter 212. The upper wafer W1, the lower wafer W2, and the bonded wafer T are loaded and unloaded through the loading / unloading port 211.

[0039] 6, an upper chuck 230 and a lower chuck 231 are provided inside the processing vessel 210. The upper chuck 230 holds the upper wafer W1 from above with the bonding surface W1j of the upper wafer W1 facing downward. The lower chuck 231 is provided below the upper chuck 230 and holds the lower wafer W2 from below with the bonding surface W2j of the lower wafer W2 facing upward.

[0040] The upper chuck 230 is supported by a support member 280 provided on the ceiling surface of the processing vessel 210. On the other hand, the lower chuck 231 is supported by a first lower chuck moving part 291 provided below the lower chuck 231.

[0041] As will be described later, the first lower chuck moving part 291 moves the lower chuck 231 in the horizontal direction (Y-axis direction). The first lower chuck moving part 291 is configured to be able to move the lower chuck 231 in the vertical direction and to rotate the lower chuck 231 around a vertical axis.

[0042] The first lower chuck moving part 291 is provided on the underside of the first lower chuck moving part 291 and is attached to a pair of rails 295 extending in the horizontal direction (Y-axis direction). The first lower chuck moving part 291 is configured to be movable along the rails 295. The rails 295 are provided on a second lower chuck moving part 296.

[0043] The second lower chuck moving part 296 is provided on the lower surface side of the second lower chuck moving part 296 and is attached to a pair of rails 297 extending in the horizontal direction (X-axis direction). The second lower chuck moving part 296 is configured to be movable along the rails 297. The pair of rails 297 is provided on a mounting table 298 provided on the bottom surface of the processing vessel 210.

[0044] The first lower chuck moving part 291 and the second lower chuck moving part 296 constitute a moving mechanism 290. The moving mechanism 290 moves the lower chuck 231 relative to the upper chuck 230. The moving mechanism 290 also moves the lower chuck 231 between a substrate transfer position and a joining position.

[0045] The substrate transfer position is a position where the upper chuck 230 receives the upper wafer W1 from the transfer device 61, the lower chuck 231 receives the lower wafer W2 from the transfer device 61, and the lower chuck 231 transfers the bonded wafer T to the transfer device 61. The substrate transfer position is a position where the bonded wafer T produced in the nth (n is a natural number greater than or equal to 1) bonding is successively transferred out and the upper wafer W1 and lower wafer W2 to be bonded in the n+1th bonding are continuously transferred in. The substrate transfer position is, for example, a position shown in FIGS.

[0046] The transfer device 61 enters directly below the upper chuck 230 when transferring the upper wafer W1 to the upper chuck 230. Furthermore, the transfer device 61 enters directly above the lower chuck 231 when receiving the bonded wafer T from the lower chuck 231 and transferring the lower wafer W2 to the lower chuck 231. To facilitate the transfer device 61's entry, the upper chuck 230 and the lower chuck 231 are shifted laterally, and the vertical distance between the upper chuck 230 and the lower chuck 231 is also large.

[0047] On the other hand, the bonding position is a position (opposing position) where the upper wafer W1 and the lower wafer W2 are faced to each other with a predetermined gap therebetween. The bonding position is, for example, the position shown in FIG. 7. At the bonding position, the gap between the upper wafer W1 and the lower wafer W2 in the vertical direction is narrower than at the substrate transfer position. Also, at the bonding position, unlike at the substrate transfer position, the upper wafer W1 and the lower wafer W2 overlap when viewed in the vertical direction.

[0048] The moving mechanism 290 moves the relative positions of the upper chuck 230 and the lower chuck 231 in the horizontal direction (both the X-axis direction and the Y-axis direction) and the vertical direction. In this embodiment, the moving mechanism 290 moves the lower chuck 231, but it may move either the lower chuck 231 or the upper chuck 230, or may move both. The moving mechanism 290 may also rotate the upper chuck 230 or the lower chuck 231 around the vertical axis.

[0049] 7, the upper chuck 230 is partitioned into a plurality of (e.g., three) regions 230a, 230b, and 230c along the radial direction of the upper chuck 230. These regions 230a, 230b, and 230c are provided in this order from the center toward the outer edge of the upper chuck 230. The region 230a is formed in a perfect circular shape in a plan view, and the regions 230b and 230c are formed in annular shapes in a plan view.

[0050] Suction pipes 240a, 240b, and 240c are independently provided in the respective regions 230a, 230b, and 230c. Different vacuum pumps 241a, 241b, and 241c are connected to the respective suction pipes 240a, 240b, and 240c. The upper chuck 230 can vacuum-suck the upper wafer W1 in each of the regions 230a, 230b, and 230c.

[0051] The upper chuck 230 is provided with a plurality of holding pins 245 that can be raised and lowered in the vertical direction. The plurality of holding pins 245 are connected to a vacuum pump 246, and vacuum-suck the upper wafer W1 by operating the vacuum pump 246. The upper wafer W1 is vacuum-sucked to the lower ends of the plurality of holding pins 245. Ring-shaped suction pads may be used instead of the plurality of holding pins 245.

[0052] The plurality of holding pins 245 are lowered by a drive unit (not shown) to protrude from the suction surface of the upper chuck 230. In this state, the plurality of holding pins 245 vacuum-suck the upper wafer W1 and receive it from the transfer device 61. Thereafter, the plurality of holding pins 245 rise, and the upper wafer W1 comes into contact with the suction surface of the upper chuck 230. Next, the upper chuck 230 vacuum-sucks the upper wafer W1 horizontally in each of the regions 230a, 230b, and 230c by operation of the vacuum pumps 241a, 241b, and 241c.

[0053] The upper chuck 230 also has a through-hole 243 at its center that passes vertically through the upper chuck 230. A pushing unit 250 is inserted into the through-hole 243. The pushing unit 250 pushes down the center of the upper wafer W1, which is disposed at a distance from the lower wafer W2, to bring the upper wafer W1 into contact with the lower wafer W2.

[0054] The pushing unit 250 has a pushing pin 251 and an outer cylinder 252 that serves as a lifting guide for the pushing pin 251. The pushing pin 251 is inserted into the through-hole 243 by, for example, a drive unit (not shown) having a built-in motor, protrudes from the suction surface of the upper chuck 230, and pushes down the center of the upper wafer W1.

[0055] The lower chuck 231 also has a plurality of partitioned regions on its suction surface 300 that suctions the lower wafer W2. The configuration of the suction surface 300 of the lower chuck 231 will be described in detail later.

[0056] A plurality of (e.g., three) holding pins 265 that can be raised and lowered in the vertical direction are provided on the lower chuck 231. The lower wafer W2 is placed on the upper ends of the plurality of holding pins 265. The lower wafer W2 may be vacuum-sucked to the upper ends of the plurality of holding pins 265.

[0057] As the multiple holding pins 265 rise, they protrude from the suction surface 300 of the lower chuck 231. In this state, the multiple holding pins 265 receive the lower wafer W2 from the transfer device 61. Thereafter, the multiple holding pins 265 descend, causing the lower wafer W2 to come into contact with the suction surface 300 of the lower chuck 231. Next, the lower chuck 231 horizontally vacuum-sucks the lower wafer W2 in multiple regions of the suction surface 300.

[0058] 8 to 10, the process of producing the bonded wafer T in step S109 of Fig. 4 will be described in detail. As shown in Fig. 8, the control device 90 causes the transfer device 61 to load the upper wafer W1 and the lower wafer W2 into the bonding module 41 (step S111). After the loading, the relative positions of the upper chuck 230 and the lower chuck 231 are the substrate transfer positions shown in Figs. 6 and 7.

[0059] Next, the control device 90 causes the moving mechanism 290 to move the relative positions of the upper chuck 230 and the lower chuck 231 from the substrate transfer position to the bonding position shown in Fig. 7 (step S112). In this step S112, the control device 90 aligns the upper wafer W1 and the lower wafer W2 using the first camera S1 and the second camera S2 as shown in Fig. 9.

[0060] The first camera S1 is fixed to the upper chuck 230 and captures an image of the lower wafer W2 held by the lower chuck 231. A plurality of reference points P21 to P23 are formed in advance on the bonding surface W2j of the lower wafer W2. The reference points P21 to P23 are formed by using patterns of electronic circuits or the like. The number of reference points can be set arbitrarily.

[0061] On the other hand, the second camera S2 is fixed to the lower chuck 231 and captures an image of the upper wafer W1 held by the upper chuck 230. A plurality of reference points P11 to P13 are formed in advance on the bonding surface W1j of the upper wafer W1. The reference points P11 to P13 are formed by using patterns of electronic circuits or the like. The number of reference points can be set arbitrarily.

[0062] 9A , the joining module 41 adjusts the relative horizontal positions of the first camera S1 and the second camera S2 using the movement mechanism 290. Specifically, the movement mechanism 290 moves the lower chuck 231 horizontally so that the second camera S2 is positioned approximately directly below the first camera S1. Then, the movement mechanism 290 finely adjusts the horizontal position of the second camera S2 so that the first camera S1 and the second camera S2 capture images of a common target X and the horizontal positions of the first camera S1 and the second camera S2 match.

[0063] Next, as shown in Fig. 9(B), the moving mechanism 290 moves the lower chuck 231 vertically upward to adjust the horizontal positions of the upper chuck 230 and the lower chuck 231. Specifically, while the moving mechanism 290 moves the lower chuck 231 horizontally, the first camera S1 sequentially images the reference points P21 to P23 of the lower wafer W2, and the second camera S2 sequentially images the reference points P11 to P13 of the upper wafer W1. Note that Fig. 9(B) shows how the first camera S1 images the reference point P21 of the lower wafer W2, and the second camera S2 images the reference point P11 of the upper wafer W1.

[0064] The first camera S1 and the second camera S2 transmit the captured image data to the control device 90. The control device 90 controls the moving mechanism 290 based on the image data captured by the first camera S1 and the image data captured by the second camera S2, and adjusts the horizontal position of the lower chuck 231 so that the reference points P11 to P13 of the upper wafer W1 and the reference points P21 to P23 of the lower wafer W2 coincide with each other when viewed in the vertical direction.

[0065] 9C, the moving mechanism 290 moves the lower chuck 231 vertically upward. As a result, the gap G (see FIG. 7) between the bonding surface W2j of the lower wafer W2 and the bonding surface W1j of the upper wafer W1 becomes a predetermined distance, for example, 80 μm to 200 μm. The gap G is adjusted using the first displacement gauge S3 and the second displacement gauge S4.

[0066] The first displacement meter S3 is fixed to the upper chuck 230 and measures the thickness of the lower wafer W2 held by the lower chuck 231. The first displacement meter S3 measures the thickness of the lower wafer W2, for example, by irradiating the lower wafer W2 with light and receiving light reflected from both the upper and lower surfaces of the lower wafer W2. The thickness measurement is performed, for example, when the moving mechanism 290 moves the lower chuck 231 in the horizontal direction. The measurement method of the first displacement meter S3 is, for example, a confocal method, a spectral interference method, or a triangulation method. The light source of the first displacement meter S3 is an LED or a laser.

[0067] On the other hand, the second displacement meter S4 is fixed to the lower chuck 231 and measures the thickness of the upper wafer W1 held by the upper chuck 230. The second displacement meter S4 measures the thickness of the upper wafer W1, for example, by irradiating light onto the upper wafer W1 and receiving light reflected from both the upper and lower surfaces of the upper wafer W1. The thickness measurement is performed, for example, when the moving mechanism 290 moves the lower chuck 231 in the horizontal direction. The measurement method of the second displacement meter S4 is, for example, a confocal method, a spectral interference method, or a triangulation method. The light source of the second displacement meter S4 is an LED or a laser.

[0068] Each of the first displacement gauges S3 and each of the second displacement gauges S4 transmits the measured measurement information to the control device 90. The control device 90 controls the moving mechanism 290 based on the measurement information measured by each of the first displacement gauges S3 and the measurement information measured by each of the second displacement gauges S4, and adjusts the vertical position of the lower chuck 231 so that the gap G becomes a set value.

[0069] Next, the operation of the vacuum pump 241a is stopped, and the vacuum suction of the upper wafer W1 in the region 230a is released, as shown in FIG. 10A. Thereafter, the pushing pin 251 of the pushing unit 250 descends to push down the center of the upper wafer W1, thereby bringing the upper wafer W1 into contact with the lower wafer W2 (step S113). As a result, the centers of the upper wafer W1 and the lower wafer W2 are bonded together.

[0070] Since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 have been modified, van der Waals forces (intermolecular forces) are generated between the bonding surfaces W1j and W2j, bonding the bonding surfaces W1j and W2j together. Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 have been hydrophilized, hydrophilic groups (e.g., OH groups) form hydrogen bonds, firmly bonding the bonding surfaces W1j and W2j together.

[0071] Next, the control device 90 stops the operation of the vacuum pump 241b, and releases the vacuum suction of the upper wafer W1 in the region 230b as shown in Fig. 11(B). Subsequently, the control device 90 stops the operation of the vacuum pump 241c, and releases the vacuum suction of the upper wafer W1 in the region 230c as shown in Fig. 11(C).

[0072] In this manner, the vacuum suction of the upper wafer W1 is gradually released from the center toward the periphery of the upper wafer W1, and the upper wafer W1 gradually drops and contacts the lower wafer W2. Then, bonding of the upper wafer W1 and the lower wafer W2 proceeds sequentially from the center toward the periphery (step S114). As a result, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 come into contact over their entire surfaces, the upper wafer W1 and the lower wafer W2 are bonded, and a bonded wafer T is obtained. Thereafter, the bonding apparatus 1 raises the pushing pin 251 to its original position.

[0073] After the bonded wafer T is formed, the control device 90 causes the moving mechanism 290 to move the relative positions of the upper chuck 230 and the lower chuck 231 from the bonding position shown in Fig. 8 to the substrate transfer position shown in Fig. 6 and Fig. 7 (step S115). For example, the moving mechanism 290 first lowers the lower chuck 231 to widen the vertical gap between the lower chuck 231 and the upper chuck 230. Next, the moving mechanism 290 moves the lower chuck 231 laterally to laterally shift the lower chuck 231 and the upper chuck 230.

[0074] Thereafter, the control device 90 causes the transfer device 61 to transfer the bonded wafer T out of the bonding module 41 (step S116). Specifically, first, the lower chuck 231 releases the bonded wafer T. Next, the multiple holding pins 265 rise and transfer the bonded wafer T to the transfer device 61. Then, the multiple holding pins 265 descend to their original positions.

[0075] Next, the configuration of the suction surface 300 of the lower chuck 231 will be described with reference to Fig. 11 . Note that the technology of the present disclosure is also applicable to the suction surface of the upper chuck 230. In Fig. 11 , the hatched areas are areas where suction pressure is generated. The suction surface 300 of the lower chuck 231 has multiple areas where suction pressure is individually generated.

[0076] For example, the suction surface 300 is partitioned into a central region A, an intermediate region B, and an outer region C by annular ribs 301, 302, and 303. The central region A, the intermediate region B, and the outer region C are concentrically arranged in this order from the center of the suction surface 300 toward the outer edge. Specifically, the central region A is formed in a perfect circle. The intermediate region B is formed in an annular shape at a position adjacent to the outer side of the central region A. The outer region C is formed in an annular shape at a position adjacent to the outer side of the intermediate region B. Note that the suction surface 300 may not include the intermediate region B, and the outer region C may be located adjacent to the outer side of the central region A. Conversely, the suction surface 300 may include multiple annular intermediate regions B between the central region A and the outer region C.

[0077] The intermediate region B is divided into eight arc-shaped zones (small regions: portions) by a plurality of radial ribs 305. Similarly, the outer region C is divided into eight arc-shaped zones by the ribs 305. The number of zones in the intermediate region B and the number of zones in the outer region C may be the same or different.

[0078] The eight zones in the central region A and the intermediate region B and the eight zones in the outer region C are configured to be able to individually suck the lower wafer W2. However, the lower chuck 231 according to this embodiment is connected to ten suction mechanisms 311 for a total of 17 zones, and the suction surface 300 is sucked for each of the ten channel zones. In other words, the suction surface 300 has zones among the total of 17 zones that are sucked by the same suction mechanism 311.

[0079] Specifically, one zone (ch1) is defined in the central region A and connected to a predetermined suction mechanism 311. Meanwhile, three zones (ch2 to ch4) are defined in the intermediate region B. The two zones adjacent to the central region A in the X-axis direction (left and right in FIG. 11 ) are ch2. The two zones adjacent to the central region A in the Y-axis direction (top and bottom in FIG. 11 ) are ch3. The four zones sandwiched between the ch2 and ch3 zones in the intermediate region B are ch4. Meanwhile, six zones (ch5 to ch10) are defined in the outer region C. The zone adjacent to the intermediate region B in the positive X-axis direction (left in FIG. 11 ) is ch5. The zone adjacent to the intermediate region B in the negative X-axis direction (right in FIG. 11 ) is ch6. The zone adjacent to the intermediate region B in the negative Y-axis direction (top in FIG. 11 ) is ch7. The zone 1 adjacent to the middle region B in the positive Y-axis direction (bottom in FIG. 11 ) is ch8. In the outer region C, the zones sandwiched between the zones ch5 and ch7 and the zones sandwiched between the zones ch6 and ch7 are ch9. Similarly, in the outer region C, the zones sandwiched between the zones ch5 and ch8 and the zones sandwiched between the zones ch6 and ch8 are ch10.

[0080] On the X-axis line passing through the center of the suction surface 300, the zones ch5, ch2, ch1, ch2, and ch6 are arranged in this order from the positive direction of the X-axis to the negative direction of the X-axis. On the Y-axis line passing through the center of the suction surface 300, the zones ch7, ch3, ch1, ch3, and ch8 are arranged in this order from the negative direction of the Y-axis to the positive direction of the X-axis. Of course, the suction surface 300 can be freely designed with regard to the number and locations of channels in each zone.

[0081] The bonding module 41 is provided with a suction pressure generator 310 that generates suction pressure individually in each zone of the 10 channels of the suction surface 300. Each suction mechanism 311 of the suction pressure generator 310 has a suction line 312 connected to a predetermined zone, and this suction line 312 is equipped with a suction pump 313, an open / close valve 314, and a pressure controller 315. The suction pressure generator 310 is communicatively connected to the control device 90, and operates each suction mechanism 311 under the control of the control device 90.

[0082] Each suction mechanism 311 generates suction pressure (negative pressure) in the zone to which the suction line 312 is connected, for example, by operating the suction pump 313 of the specified suction line 312 and opening the open / close valve 314. The magnitude of the suction pressure is controlled by a pressure controller 315. Furthermore, each suction mechanism 311 releases the suction pressure in each zone by closing the open / close valve 314 of the specified suction line 312 and introducing air via the pressure controller 315.

[0083] Next, warpage occurring in the lower wafer W2 will be described with reference to Fig. 12. In Fig. 12(A), the black and white gradation represents the height of the upper surface (bonding surface W2j) of the lower wafer W2 relative to the chucking surface 300 of the lower chuck 231. The closer the color is to black, the lower the height of the upper surface of the lower wafer W2 and the smaller the distance between the upper surface of the lower wafer W2 and the chucking surface 300 of the lower chuck 231.

[0084] The warpage of the lower wafer W2 is measured, for example, by a warpage measuring device 5 (see FIG. 1 ) provided separately from the bonding apparatus 1, and the control device 90 acquires information on the warpage state of the lower wafer W2 measured by the warpage measuring device 5. The warpage measuring device 5 may be provided as part of the bonding apparatus 1. The bonding apparatus 1 may be configured to measure the warpage when the upper wafer W1 and the lower wafer W2 are loaded using a plurality of displacement meters (not shown) provided in the bonding module 41.

[0085] Before the suction pressure generating unit 310 (see FIG. 11 ) generates a suction pressure on the suction surface 300 of the lower chuck 231, the lower wafer W2 may be warped as shown in FIG. 12A . The warping of the lower wafer W2 occurs, for example, when multiple films are stacked on a semiconductor substrate such as a silicon wafer. Each film is formed by a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, a spin-on method, or the like. Stress is applied to the lower wafer W2 due to differences in thermal expansion during film formation, causing the warping of the lower wafer W2.

[0086] The lower wafer W2 is often warped symmetrically across two orthogonal radial lines, i.e., line-symmetrically. This is because the Young's modulus, Poisson's ratio, and shear modulus of elasticity of a semiconductor substrate such as a silicon wafer change in a 90° cycle. The two orthogonal radial lines extend in a specific crystal orientation of the semiconductor substrate when viewed from the direction orthogonal to the chucking surface 300 (the Z-axis direction).

[0087] Then, the bonding apparatus 1 transfers the lower wafer W2 from the transfer device 61 to the lower chuck 231 so that two perpendicular radial lines of the lower wafer W2 are aligned with the X-axis direction and the Y-axis direction of the lower chuck 231. For example, the orientation (posture) of the lower wafer W2 is adjusted by the above-described second position adjustment device 52 (see FIG. 2).

[0088] The warpage of the lower wafer W2 can be classified into two types: one in which the outer edge at a symmetrical position warps in a direction (vertically downward) toward the suction surface 300 when the center of the lower wafer W2 is used as a base point, and the other in which the outer edge at a symmetrical position warps in a direction (vertically upward) away from the suction surface 300. Hereinafter, downward warpage of the outer edge of the lower wafer W2 is referred to as negative warpage (first type), and upward warpage of the outer edge of the lower wafer W2 is referred to as positive warpage (second type).

[0089] Here, when a disk-shaped member such as the lower wafer W2 is convexly curved from the two outer edges toward the center on the Y-axis, it presents a saddle-shaped curved surface that is concavely curved from the two outer edges toward the center on the X-axis, which is offset by 90 degrees in the circumferential direction. Therefore, the warpage of the lower wafer W2 is in opposite directions on two orthogonal radial lines. In other words, when negative warpage occurs at the outer edge in the Y-axis direction as shown in FIG. 12(B), positive warpage occurs at the outer edge in the X-axis direction as shown in FIG. 12(C).

[0090] Next, the influence of the warpage state of the lower wafer W2 on the bonding surface W2j will be described with reference to Fig. 13. In Fig. 13, for ease of understanding, the cross section of the lower wafer W2 in the Y-axis direction is shown in black, and the cross section of the lower wafer W2 in the X-axis direction is shown in white, with the two overlapping.

[0091] The bonding surface W2j, which is the upper surface of the lower wafer W2, expands and contracts in accordance with warpage that occurs throughout the lower wafer W2. In a cross section along the radial direction (Y-axis direction in FIG. 13) where negative warpage occurs, a pair of outer edges are lowered vertically relative to the center, causing the bonding surface W2j to expand. On the other hand, in a cross section along the radial direction (X-axis direction in FIG. 13) where positive warpage occurs, a pair of outer edges are raised vertically relative to the center, causing the bonding surface W2j to contract.

[0092] However, the expansion and contraction occurring at the joint surface W2j may differ depending on the amount of warping of the outer edge relative to the center in the X-axis direction and the amount of warping of the outer edge relative to the center in the Y-axis direction. For example, as shown in Fig. 13, if the amount of negative warping in the Y-axis direction is -300 µm and the amount of positive warping in the X-axis direction is +70 µm, it can be said that the joint surface W2j has expanded significantly in the Y-axis direction but has shrunk slightly in the X-axis direction.

[0093] In this way, when the influence of elongation on the bonding surface W2j is large, the lower chuck 231 suctions the lower wafer W2 so that the bonding surface W2j shrinks in the radial direction (the Y-axis direction in FIG. 13 ) in which the elongation occurs, thereby improving the distribution of residual stress on the lower wafer W2. Specifically, when the lower chuck 231 suctions the lower wafer W2, the bonding apparatus 1 sequentially suctions the lower wafer W2 from the outer edge toward the center. In this way, by first fixing the outer edge of the lower wafer W2, the lower chuck 231 can induce the bonding surface W2j to shrink toward the center of the lower wafer W2. Hereinafter, the suction operation from the outer edge toward the center of the lower wafer W2 on the suction surface 300 is referred to as the outer center pattern.

[0094] Conversely, when the shrinkage has a large effect on the bonding surface W2j, the lower chuck 231 suctions the lower wafer W2 so that the bonding surface W2j stretches in the radial direction (the X-axis direction in FIG. 13 ) in which the shrinkage occurs, thereby improving the distribution of residual stress in the lower wafer W2. Specifically, when the lower chuck 231 suctions the lower wafer W2, the bonding apparatus 1 sequentially suctions the lower wafer W2 from the center toward the outer edge of the lower wafer W2. As a result, the lower chuck 231 first fixes the center of the lower wafer W2, thereby guiding the bonding surface W2j to stretch toward the outer edge of the lower wafer W2. Hereinafter, the suction operation from the center toward the outer edge of the lower wafer W2 on the suction surface 300 is referred to as the "center-outer pattern."

[0095] The control device 90 of the bonding apparatus 1 selects the outer central pattern and the central outer pattern according to the state of warpage of the lower wafer W2, thereby improving the distribution of residual stress in the lower wafer W2 attracted to the suction surface 300. For example, the control device 90 compares the absolute value of the warpage amount of the lower wafer W2 in the X-axis direction with the absolute value of the warpage amount in the Y-axis direction, and selects the outer central pattern and the central outer pattern based on the warpage type (negative warpage, positive warpage) with the larger absolute value of the warpage amount. When attracting the lower wafer W2, among the zones in the circumferential direction of the outer region C, an outer first zone that attracts the lower wafer W2 by suction and an outer second zone that attracts the lower wafer W2 later than the outer first zone are set. For example, as shown in FIG. 11 , the outer first zone is a zone (ch7, ch8) along the Y-axis direction of the suction surface 300, and the outer second zone is a zone (ch5, ch6) that is shifted 90 degrees in phase from the outer first zone along the circumferential direction of the suction surface 300. Alternatively, the outer first zone may be a zone (ch5, ch6) along the X-axis direction of the adsorption surface 300, in which case the outer second zone may be a zone (ch7, ch8) that is 90° out of phase with the outer first zone along the circumferential direction of the adsorption surface 300.

[0096] The joining device 1 may also set an intermediate first zone and an intermediate second zone within each zone of the intermediate region B. The intermediate first zone is a zone located adjacent to the outer first zone. When ch7 and ch8 are the outer first zone and ch5 and ch6 are the outer second zone, ch3 becomes the intermediate first zone and ch2 becomes the intermediate second zone. When ch5 and ch6 are the outer first zone and ch7 and ch8 are the outer second zone, ch2 becomes the intermediate first zone and ch3 becomes the intermediate second zone.

[0097] However, the control device 90 may more precisely adjust the timing of the suction operation of each zone for suctioning the lower wafer W2, such as performing the outer central pattern first and then the central outer pattern, when suctioning the lower wafer W2 with the lower chuck 231. This makes it possible to further disperse residual stress in the lower wafer W2. Below, the operation when suctioning the lower wafer W2 with the lower chuck 231 will be specifically described.

[0098] First, a case will be described in which negative warpage occurs along the Y-axis direction, positive warpage occurs along the X-axis direction, and the absolute value of the amount of warpage in the Y-axis direction is greater than the absolute value of the amount of warpage in the X-axis direction, as shown in Figure 13. In this case, as described above, the bonding surface W2j of the lower wafer W2 extends mainly along the Y-axis direction. Therefore, the control device 90 determines to perform the outer central pattern in the Y-axis direction first. Furthermore, based on the fact that positive warpage has occurred along the X-axis direction, the control device 90 also determines to perform the outer central pattern in the Y-axis direction after the outer central pattern in the X-axis direction.

[0099] When the control device 90 lowers the plurality of holding pins 265 to suck the lower wafer W2, it generates suction pressure in accordance with the set order of the suction operation of each channel, as shown in Fig. 14. In Fig. 14, the zones (channels) in which suction pressure is generated are hatched.

[0100] 14A, the control device 90 first generates suction pressure in ch7 and ch8, which are zones in the outer region C in the Y-axis direction. This allows the lower chuck 231 to first fix the outer edge of the joining surface W2j extending in the Y-axis direction.

[0101] 14(B), the control device 90 generates suction pressure in ch1, which is the central zone (central region A) of the suction surface 300. As a result, when viewed in a cross section in the Y-axis direction, an outer central pattern is performed in which suction pressure is generated from the outer edge side to the center side of the lower wafer W2. As a result, the bonding surface W2j of the lower wafer W2 is fixed in a direction contracting in the Y-axis direction.

[0102] 14(C), the control device 90 generates suction pressure in two ch3s, which are zones adjacent to ch1 in the intermediate region B. This prevents the bonding surface W2j in the Y-axis direction from shrinking too much toward the center, dispersing the residual stress of the lower wafer W2 to the periphery, and fixes the lower wafer W2 along the Y-axis direction. Note that the control device 90 may be configured to generate suction pressure in the order of ch7, ch8, each ch3, and ch1 in the outer central pattern performed first.

[0103] Next, as shown in FIG. 14(D), the control device 90 generates suction pressure in two ch2 zones adjacent to ch1 in the intermediate region B to perform a central outer pattern in the X-axis direction. Furthermore, as shown in FIG. 14(E), the control device 90 generates suction pressure in ch5 and ch6 zones adjacent to each ch2 in the outer region C. As a result, when viewed in a cross section in the X-axis direction, a central outer pattern is performed in which suction pressure is generated from the center to the outer edge of the lower wafer W2. As a result, the bonding surface W2j of the lower wafer W2 is fixed in a direction extending in the X-axis direction. Alternatively, the control device 90 may be configured to generate suction pressure in the order of ch1 → ch5, ch6 → ch2 in the central outer pattern. This prevents the bonding surface W2j in the X-axis direction from extending too far toward the outer edge, thereby dispersing residual stress to the surroundings.

[0104] After suction in the X-axis and Y-axis directions, the control device 90 performs suction in the diagonal direction between the X-axis and Y-axis directions, as shown in Fig. 14(F). In this diagonal suction, the control device 90 first generates suction pressure in the four channels ch4 in the intermediate region B.

[0105] Furthermore, the control device 90 generates suction pressure in two ch9s and two ch10s, which are zones of the outer region C (see FIG. 11 ). This allows the lower chuck 231 to suction the lower wafer W2 using all zones of the suction surface 300 while stretching the lower wafer W2 in the diagonal direction. Note that, for example, if the extension of the bonding surface W2j of the lower wafer W2 is large, suction pressure may also be generated in the diagonal direction in the order of the outer region C (ch9, ch10) → the middle region B (ch4).

[0106] As described above, the bonding apparatus 1 can improve the distribution of residual stress in the lower wafer W2 by performing the outer central pattern and the central outer pattern depending on the state of warpage of the lower wafer W2. The above-described suction operation is an example in which there is positive warpage in the X-axis direction, negative warpage in the Y-axis direction, and the absolute value of the warpage amount in the Y-axis direction is greater than the absolute value of the warpage amount in the X-axis direction. The control device 90 performs a different suction operation for a different state of warpage of the lower wafer W2.

[0107] As an example, the control device 90 may select a suction operation according to a plurality of conditions, as shown in the table of Fig. 15. Note that the top row (first row) in the table of Fig. 15 shows examples of the warpage state of the lower wafer W2 and the suction operation described with reference to Figs.

[0108] The second row in the table of Figure 15 shows a case where the X-axis direction is positive warpage and the Y-axis direction is negative warpage, and the relationship between the warpage amounts is such that the absolute value of the warpage amount in the X-axis direction is greater than the absolute value of the warpage amount in the Y-axis direction. In this case, it can be said that the bonding surface W2j of the lower wafer W2 is mainly shrunk in the X-axis direction. Therefore, the control device 90 determines that the central outer pattern should be performed in the X-axis direction. Therefore, in the suction operation, suction pressure is generated in the order of ch1 → ch2 → ch5, and ch6 as the central outer pattern in the X-axis direction.

[0109] Thereafter, the control device 90 generates suction pressure in the order of ch7, ch8, and ch3 in the Y-axis direction, and then generates suction pressure in the order of ch4, ch9, and ch10 in the diagonal direction. This allows the bonding surface W2j to be induced to shrink slightly in the Y-axis direction where negative warpage occurs. Alternatively, if the absolute value of the amount of warpage in the Y-axis direction is small, after the central outer pattern in the X-axis direction, suction pressure may also be generated in the order of ch1, ch3, ch7, and ch8 as a central outer pattern in the Y-axis direction.

[0110] 15 shows a case where the X-axis direction is positive warpage and the Y-axis direction is negative warpage, and the relationship between the amount of warpage is such that the absolute value of the amount of warpage in the X-axis direction is approximately equal to the absolute value of the amount of warpage in the Y-axis direction. In other words, it can be said that the amount of contraction of the bonding surface W2j of the lower wafer W2 in the X-axis direction is approximately equal to the amount of expansion in the Y-axis direction. In this case, the control device 90 generates suction pressure in the following order during the suction operation: ch1, ch7, ch8 → ch2 → ch5, ch6 → ch3 → ch4 → ch9, ch10.

[0111] That is, the lower chuck 231 can first fix the bonding surface W2j in the Y-axis direction by simultaneously suctioning the central region A and the outer region C in the Y-axis direction. Thereafter, by performing the central outer pattern in the X-axis direction in the same manner as in the first row, the bonding surface W2j can be extended in the X-axis direction.

[0112] 15 shows a case where the X-axis direction is negative warpage, the Y-axis direction is positive warpage, and the relationship between the warpage amounts is such that the absolute value of the warpage amount in the X-axis direction is less than the absolute value of the warpage amount in the Y-axis direction. In this case, it can be said that the bonding surface W2j of the lower wafer W2 is mainly shrunk in the Y-axis direction. Therefore, the control device 90 determines that the central outer pattern should be performed in the Y-axis direction. Therefore, in the suction operation, suction pressure is generated in the order of ch1 → ch3 → ch7, and ch8 as the central outer pattern in the Y-axis direction.

[0113] Thereafter, the control device 90 generates suction pressure in the order of ch5, ch6, and ch2 in the X-axis direction, and further generates suction pressure in the order of ch4, ch9, and ch10 in the diagonal direction. Note that if the absolute value of the warpage amount in the X-axis direction is small, suction pressure may be generated in the order of ch1, ch2, ch5, and ch6 as the central outer pattern in the X-axis direction after the central outer pattern in the Y-axis direction.

[0114] The fifth row in the table of FIG. 15 shows a case where the X-axis direction is negative warpage, the Y-axis direction is positive warpage, and the relationship between the warpage amounts is such that the absolute value of the warpage amount in the X-axis direction is greater than the absolute value of the warpage amount in the Y-axis direction. In this case, it can be said that the bonding surface W2j of the lower wafer W2 extends mainly in the X-axis direction. Therefore, the control device 90 determines to perform the outer central pattern in the X-axis direction. Therefore, in the suction operation, as the outer central pattern in the X-axis direction, suction pressure is generated in the order of ch5, ch6, and ch1. Thereafter, the control device 90 generates suction pressure in ch2 in the X-axis direction. Note that the control device 90 may generate suction pressure in the order of ch5, ch6, ch2, and ch1 in the X-axis direction, depending on the warpage state of the lower wafer W2.

[0115] Furthermore, the control device 90 generates suction pressure in the order of ch3 → ch7, ch8 in the Y-axis direction, and then generates suction pressure in the order of ch4 → ch9, ch10 in the diagonal direction. Alternatively, if the absolute value of the warpage amount in the Y-axis direction is large, the control device 90 may generate suction pressure in the order of ch7, ch8, ch3.

[0116] 15 shows a case where the X-axis direction is negative warpage, the Y-axis direction is positive warpage, and the relationship between the amount of warpage is such that the absolute value of the amount of warpage in the X-axis direction is approximately equal to the absolute value of the amount of warpage in the Y-axis direction. In this case, it can be said that the amount of expansion of the bonding surface W2j of the lower wafer W2 in the X-axis direction is approximately equal to the amount of contraction in the Y-axis direction. Therefore, during the suction operation, the control device 90 generates suction pressure in the order of ch1, ch5, ch6 → ch3 → ch7, ch8 → ch2 → ch4 → ch9, and ch10.

[0117] That is, the lower chuck 231 can first fix the joining surface W2j in the X-axis direction by simultaneously suctioning the central region A and the outer region C in the X-axis direction. Thereafter, by performing the central outer pattern in the Y-axis direction in the same manner as in the fourth row, the joining surface W2j can be extended in the Y-axis direction.

[0118] As described above, the substrate processing apparatus (bonding apparatus 1) can improve the distribution of residual stress in the lower wafer W2 and appropriately adsorb the lower wafer W2 by selecting the outer central pattern or the central outer pattern depending on the warpage state of the lower wafer W2. That is, when the bonding surface W2j is expanded, adsorption from the outer region C toward the central region A using the outer central pattern makes it possible to apply stress in a direction that shrinks the bonding surface W2j. Conversely, when the bonding surface W2j is expanded, adsorption from the central region A toward the outer region C using the central outer pattern makes it possible to apply stress in a direction that expands the bonding surface W2j.

[0119] Furthermore, when warpage occurs in the orthogonal radial directions (X-axis direction, Y-axis direction) of the lower wafer W2, the bonding apparatus 1 can stably perform the outer central pattern and the central outer pattern by selecting the outer first zone and the outer second zone. In particular, the bonding apparatus 1 compares the amount of warpage of negative warpage with the amount of warpage of positive warpage, and performs the outer central pattern and the central outer pattern based on the form with the larger absolute value of the amount of warpage, thereby more reliably dispersing the residual stress of the lower wafer W2.

[0120] Furthermore, after performing the outer central pattern, the bonding apparatus 1 generates suction pressure in the direction from the central region A to the outer region C, thereby smoothly stretching the bonding surface W2j and improving the distribution of residual stress on the lower wafer W2. Furthermore, by omitting the intermediate first zone in the outer central pattern, the bonding apparatus 1 can effectively release stress to its periphery, resulting in further dispersion of residual stress.

[0121] It should be noted that the substrate processing apparatus (bonding apparatus 1) according to the present disclosure is not limited to the above configuration and may, of course, be modified in various ways. For example, when the lower wafer W2 is warped in the diagonal direction, the bonding apparatus 1 may first perform suction in the diagonal direction, and in this case, the outer central pattern and the central outer pattern can be selected as appropriate.

[0122] 15 by comparing the magnitude relationship between the absolute value of the negative warpage and the absolute value of the positive warpage of the lower wafer W2, but the present invention is not limited to this. For example, the outer central pattern may be uniformly performed in the radial direction in which the negative warpage occurs in the lower wafer W2, and the central outer pattern may be uniformly performed in the radial direction in which the positive warpage occurs.

[0123] Furthermore, in the above embodiment, the suction pressure when suctioning the lower wafer W2 is set to be the same between the respective zones, but this is not limitative, and different suction pressures may be set between the respective zones.

[0124] Second Embodiment Next, a welding module 41A according to a second embodiment will be described with reference to Figures 16 and 17. The welding module 41A differs from the welding module 41A according to the first embodiment in that it includes a lower chuck 231A that forms a curved suction surface 400.

[0125] The lower chuck 231A includes, for example, a base portion 232 and a suction portion 233. The suction portion 233 is provided above the base portion 232 and suction-holds the lower wafer W2 from below. The suction portion 233 is formed in a perfect circle with a diameter larger than that of the lower wafer W2 in a plan view and is fixed to the base portion 232 by a fixing ring 234 provided on the periphery. A pressure variable space 235 is formed between the upper surface of the base portion 232 and the lower surface of the suction portion 233.

[0126] As in the first embodiment, annular ribs 301, 302, and 303 and radial ribs 305 (see FIG. 11 ) are provided on the upper surface of the suction portion 233. As shown in FIG. 11 , these ribs 301, 302, 303, and 305 also configure the suction surface 400 to have a central region A, an intermediate region B, and an outer region C, and the intermediate region B and the outer region C are configured to have a plurality of zones in the circumferential direction. The plurality of zones are set as a plurality of channels (ch1 to ch10) that individually suction the lower wafer W2.

[0127] The bonding module 41A includes a second deformation unit 236 that deforms the lower chuck 231A to curve the lower wafer W2. The second deformation unit 236 changes the pressure in the pressure variable space 235 to elastically deform the suction unit 233. The suction unit 233 is made of a ceramic material such as alumina or silicon carbide. The second deformation unit 236 includes a vacuum pump 236a, a pressure pump 236b, and a switching valve 236c.

[0128] The vacuum pump 236a depressurizes the pressure variable space 235 by discharging gas therein. By depressurizing the pressure variable space 235, the upper surface of the adsorption part 233 becomes horizontal. The pressure pump 236b pressurizes the pressure variable space 235 by supplying gas to the pressure variable space 235. By pressurizing the pressure variable space 235, the adsorption surface 400 of the adsorption part 233 becomes a curved surface with a protruding central region A. The protrusion amount of the central region A of the adsorption surface 400 can be adjusted by the pressure in the pressure variable space 235. The switching valve 236c switches the pressure variable space 235 between a state where it is connected to the vacuum pump 236a and a state where it is connected to the pressure pump 236b.

[0129] The base part 232 has a measurement part 237 that measures the amount of protrusion of the central region A of the adsorption surface 400. A measurement target 237a of the measurement part 237 moves up and down together with the central part of the adsorption part 233. The measurement part 237 is, for example, a capacitance sensor, and measures the amount of protrusion by detecting capacitance that changes depending on the distance from the measurement target 237a.

[0130] 16 , the bonding module 41A configured as described above deforms the suction surface 400 of the lower chuck 231A and suctions the lower wafer W2 transferred by the transfer device 61. When suctioning the lower wafer W2, the control device 90 appropriately performs either the outer central pattern for suctioning the lower wafer W2 from the outside or the central outer pattern for suctioning the lower wafer W2 from the center, depending on the warpage state of the lower wafer W2, as described above.

[0131] In selecting the outer central pattern and the central outer pattern, the control device 90 makes a judgment taking into account the amount of protrusion of the central region A of the suction surface 400 (the curvature of the entire suction surface 400) in addition to the warpage state of the lower wafer W2.

[0132] 17, if the suction surface 400 of the lower chuck 231A protrudes by 150 μm while the outer edge of the lower wafer W2 in the Y-axis direction has a negative warpage of −300 μm, the curvature of the lower wafer W2 in the Y-axis direction will be greater than the curvature of the suction surface 400 in the Y-axis direction. In this case, the control device 90 selects an outer center pattern in which the suction operation is performed from the outer edge (ch7, ch8: see FIG. 11) of the lower wafer W2 toward the center (ch1: see FIG. 11). This makes it possible to suppress extension of the outer edge of the lower wafer W2 in the Y-axis direction.

[0133] On the other hand, if the suction surface 400 of the lower chuck 231A protrudes 150 μm while the outer edge of the lower wafer W2 in the Y-axis direction has a negative warpage of −100 μm, the curvature of the lower wafer W2 in the Y-axis direction will be smaller than the curvature of the suction surface 400 in the Y-axis direction. In this case, even if the bonding surface W2j of the lower wafer W2 extends in the Y-axis direction, the amount of extension is smaller than when the lower chuck 231A is placed. Therefore, the control device 90 selects a center-outer pattern in which the suction operation is performed from the center (ch1: see FIG. 11 ) of the lower wafer W2 toward the outer edge (ch7, ch8: see FIG. 11 ). This allows the bonding surface W2j of the lower wafer W2 in the Y-axis direction to extend in accordance with the curvature of the suction surface 400.

[0134] Note that if the outer edge of the lower wafer W2 has a positive warpage (for example, in the X-axis direction in FIG. 17 ), the warpage will be opposite to the curve of the suction surface 400. For this reason, the control device 90 always selects the central outer pattern for positive warpage. This allows the bonding module 41A to smoothly stretch the bonding surface W2j in response to the positive warpage of the lower wafer W2.

[0135] As described above, in the bonding module 41A according to the second embodiment, by selecting the outer-center pattern or the central-outer pattern to adsorb the lower wafer W2, the distribution of residual stress in the lower wafer W2 can be improved. In particular, in the bonding module 41, the adsorption surface 400 is formed into a curved surface, which can reduce the difference in elongation rate between the upper wafer W1 and the lower wafer W2 during bonding and reduce the misalignment between the upper wafer W1 and the lower wafer W2 after bonding.

[0136] The substrate processing apparatus and substrate processing method according to the presently disclosed embodiments are illustrative in all respects and are not limiting. The embodiments may be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments may be configured differently and may be combined within a consistent range.

[0137] This application claims priority from basic application No. 2022-135106, filed with the Japan Patent Office on August 26, 2022, the entire contents of which are incorporated herein by reference.

[0138] REFERENCE SIGNS LIST 1 Bonding device (substrate processing device) 90 Control device (control unit) 231, 231A Lower chuck (holding unit) 300, 400 Suction surface 310 Suction pressure generating unit A Central region C Outer region W2 Lower wafer

Claims

1. a holder having an adsorption surface for adsorbing the substrate, the adsorption surface including a circular central region and an annular outer region disposed outside the central region; an adsorption pressure generating unit that generates an adsorption pressure individually in the central region, an outer first zone that is set at a portion in the circumferential direction of the outer region, and an outer second zone that is set at a portion in the circumferential direction of the outer region different from the outer first zone; A control unit that controls the suction pressure generating unit, the control unit selects, according to a warpage state of the substrate, an outer central pattern in which suction pressure is generated in the outer first zone and then in the central region, and a central outer pattern in which suction pressure is generated in the central region and then in the outer first zone. Substrate processing equipment.

2. the substrate has a first shape in which an outer edge of the substrate is warped in a direction approaching the suction surface with respect to a center of the substrate, or a second shape in which an outer edge of the substrate is warped in a direction away from the suction surface with respect to a center of the substrate, before the control unit generates a suction pressure on the suction surface; the control unit performs the outer central pattern when the predetermined radial direction of the substrate is in the first configuration, and performs the central outer pattern when the predetermined radial direction of the substrate is in the second configuration. The substrate processing apparatus according to claim 1 .

3. The substrate has a radial direction of the first shape and a radial direction of the second shape perpendicular to each other at a center thereof, the outer first zone and the outer second zone are set at positions that are out of phase with each other by 90° along the circumferential direction of the adsorption surface; The substrate processing apparatus according to claim 2 .

4. the control unit compares an amount of warping of an outer edge of the substrate with respect to a center of the substrate in the first form with an amount of warping of an outer edge of the substrate with respect to a center of the substrate in the second form, performing the outer central pattern when the absolute value of the warpage of the first type is greater than the absolute value of the warpage of the second type; performing the central outer pattern when the absolute value of the warpage of the first form is smaller than the absolute value of the warpage of the second form; The substrate processing apparatus according to claim 3 .

5. the control unit performs the outer central pattern in a radial direction of the first shape of the substrate, and then generates a suction pressure in the central region and the outer second zone in the radial direction of the second shape of the substrate in this order. The substrate processing apparatus according to claim 4 .

6. the adsorption surface includes an annular intermediate region between the central region and the outer region, the intermediate region has an intermediate first zone adjacent to the outer first zone and an intermediate second zone adjacent to the outer second zone; the control unit generates a suction pressure in the central outer pattern in the order of the central region, the intermediate first zone, and the outer first zone. The substrate processing apparatus according to claim 1 .

7. the control unit generates a suction pressure in the outer first zone and the central region in that order, omitting the intermediate first zone in the outer central pattern. The substrate processing apparatus according to claim 6 .

8. The adsorption surface is formed into a curved surface in which the central region protrudes more than the outer region. The substrate processing apparatus according to claim 1 .

9. when an outer edge of the substrate is warped in a direction approaching the suction surface with respect to a center of the substrate, the control unit compares a curvature associated with the warp of the substrate with a curvature of the suction surface; performing the outer central pattern when the curvature of the substrate is greater than the curvature of the adsorption surface; performing the central outer pattern when the curvature of the substrate is smaller than the curvature of the adsorption surface; The substrate processing apparatus according to claim 8 .

10. the control unit acquires measurement information of the warpage of the substrate, and selects the outer central pattern or the central outer pattern based on the measurement information. The substrate processing apparatus according to claim 1 .

11. the substrate processing apparatus is a bonding apparatus that bonds the substrate held by the holding unit to another substrate disposed in an opposing position to the substrate; The substrate processing apparatus according to claim 1 .

12. The holding portion is a lower chuck that adsorbs and holds the substrate below the other substrate in a vertical direction. The substrate processing apparatus of claim 11 .

13. A substrate processing method for processing a substrate while the substrate is attracted to an attraction surface of a holder, comprising the steps of: a step of generating an adsorption pressure individually by an adsorption pressure generating unit for a circular central region set on the adsorption surface, an outer first zone set at a portion in the circumferential direction of an annular outer region arranged outside the central region, and an outer second zone set at a portion in the circumferential direction of the outer region different from the outer first zone, before the step of generating the suction pressure, an outer central pattern for generating the suction pressure in the outer first zone and then in the central region, and a central outer pattern for generating the suction pressure in the central region and then in the outer first zone, in accordance with a warpage state of the substrate; In the step of generating the chucking pressure, the substrate is chucked onto the chucking surface in the order of a selected pattern. A method for processing a substrate.

14. Before the adsorption pressure is generated on the adsorption surface in the step of generating the adsorption pressure, the substrate has a first shape in which an outer edge of the substrate is warped toward the adsorption surface relative to a center of the substrate, or a second shape in which an outer edge of the substrate is warped away from the adsorption surface relative to a center of the substrate, In the step of generating the suction pressure, the outer central pattern is performed when the predetermined radial direction of the substrate is in the first configuration, while the central outer pattern is performed when the predetermined radial direction of the substrate is in the second configuration. The method of claim 13.

15. The substrate has a radial direction of the first shape and a radial direction of the second shape that are mutually perpendicular at a center, the outer first zone and the outer second zone are set at positions that are out of phase with each other by 90° along the circumferential direction of the adsorption surface; The method of claim 14.

16. Comparing the amount of warping of the outer edge of the substrate in the first form relative to the center with the amount of warping of the outer edge of the substrate in the second form relative to the center, In the step of generating the adsorption pressure, performing the outer central pattern when the absolute value of the warpage of the first type is greater than the absolute value of the warpage of the second type; performing the central outer pattern when the absolute value of the warpage of the first form is smaller than the absolute value of the warpage of the second form; The method of claim 15.

17. In the step of generating the suction pressure, after performing the outer central pattern in the radial direction of the first configuration of the substrate, the suction pressure is generated in the central region and the outer second zone in the radial direction of the second configuration of the substrate, in that order. The method of claim 16.

18. The adsorption surface has an annular intermediate region between the central region and the outer region, the intermediate region has an intermediate first zone adjacent to the outer first zone and an intermediate second zone adjacent to the outer second zone; In the step of generating the suction pressure, the suction pressure is generated in the central outer pattern in the following order: the central region, the intermediate first zone, and the outer first zone. The substrate processing method according to any one of claims 13 to 17.

19. In the step of generating the suction pressure, the suction pressure is generated in the outer central pattern in the order of the outer first zone and the central region, omitting the intermediate first zone. The method of claim 18.

20. The adsorption surface is formed into a curved surface in which the central region protrudes more than the outer region. The substrate processing method according to any one of claims 13 to 17.

21. When an outer edge of the substrate is warped in a direction approaching the adsorption surface with respect to the center of the substrate, a curvature due to the warping of the substrate is compared with a curvature of the adsorption surface; In the step of generating the adsorption pressure, performing the outer central pattern when the curvature of the substrate is greater than the curvature of the adsorption surface; performing the central outer pattern when the curvature of the substrate is smaller than the curvature of the adsorption surface; The method of claim 20.