Substrate bonding apparatus and substrate bonding method

Abstract

To provide a substrate bonding apparatus and a substrate bonding method.SOLUTION: A substrate bonding apparatus forms a contact area where a first substrate 211 and a second substrate 213 come into contact at the center of the first substrate 211 and the second substrate 213, and bonds the first substrate 211 and the second substrate 213 together such that the contact area expands from the center, using the contact area formed at the center as the starting point for bonding. A bonding portion 300 includes an upper stage 322 and a lower stage 332 which are holding portions which hold at least one of the first substrate 211 and the second substrate, an observation portion 344 which is a detection portion which detects that a contact area has been formed at the center, and a control portion 150 which releases the holding of at least one of the first substrate 211 and the second substrate by the holding portions in response to the detection portion detecting that a contact area has been formed at the center.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a substrate bonding apparatus and a substrate bonding method.

Background Art

[0002] There is an apparatus that activates the surfaces of two substrates and bonds the two substrates by bringing the activated surfaces into contact with each other (see, for example, Patent Document 1). Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-258377

[0003] The time required from the start to the completion of bonding may vary depending on the conditions of the two substrates to be bonded. Therefore, when it is considered that the bonding is completed when a certain time has elapsed since the start of bonding, by setting the certain time longer, the variation in the bonding time can be absorbed. As a result, when bonding a substrate whose actual bonding time is shorter than the set time, a waiting time occurs from when the bonding is completed until the next process is started, and that waiting time is wasted.

Summary of the Invention

[0004] In a first aspect of the present invention, a contact area where a first substrate and a second substrate contact is formed at a central portion of the first substrate and the second substrate, and using the contact area formed at the central portion as a starting point of bonding, a substrate bonding apparatus that bonds the first substrate and the second substrate so that the contact area expands from the central portion, including a holding portion that holds at least one of the first substrate and the second substrate, a detection portion that detects that the contact area is formed at the central portion, and a control portion that releases the holding of at least one of the first substrate and the second substrate by the holding portion in response to the detection portion detecting that the contact area is formed at the central portion, is provided.

[0005] In a second aspect of the present invention, a substrate bonding apparatus is provided which forms a contact area in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact, and bonds the first substrate and the second substrate with the contact area formed in the center as the starting point for bonding, such that the contact area expands from the center, the apparatus comprising a detection unit for detecting that the contact area has been formed in the center, the detection unit for detecting that the contact area has been formed in the center by detecting information relating to a change in the electrical characteristics of at least one of the first substrate and the second substrate.

[0006] In a third aspect of the present invention, a substrate bonding apparatus is provided which forms a contact area in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact, and bonds the first substrate and the second substrate with the contact area formed in the center as the starting point for bonding, such that the contact area expands from the center, the apparatus comprising a detection unit for detecting that the contact area has been formed in the center, the detection unit for detecting that the contact area has been formed in the center by detecting vibrations generated on one side of the first substrate and the second substrate on the other side of the first substrate and the second substrate.

[0007] A fourth aspect of the present invention provides a substrate bonding apparatus that forms a contact area in the center of the first substrate and the second substrate where the first substrate and the second substrate come into contact, and bonds the first substrate and the second substrate using the contact area formed in the center as the starting point for bonding, such that the contact area expands from the center, the apparatus comprising: a holding unit for holding at least one of the first substrate and the second substrate; a determination unit for determining whether a predetermined bonding force has been secured in the contact area; and a control unit for releasing the holding unit from the holding unit of at least one of the first substrate and the second substrate in response to the determination unit determining that the bonding force has been secured.

[0008] A fifth aspect of the present invention provides a substrate bonding method comprising: forming a contact region in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact; bonding the first substrate and the second substrate with the contact region formed in the center as the starting point for bonding, such that the contact region expands from the center, the method comprising: a detection step of detecting that the contact region has been formed in the center; and a release step of releasing the holding of at least one of the first substrate and the second substrate in response to the detection step of detecting that the contact region has been formed in the center.

[0009] A sixth aspect of the present invention provides a substrate bonding method comprising forming a contact region in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact, and bonding the first substrate and the second substrate with the contact region formed in the center as the starting point for bonding, such that the contact region expands from the center, the method including a detection step of detecting that the contact region has been formed in the center, the detection step of detecting that the contact region has been formed in the center by detecting information relating to a change in the electrical characteristics of at least one of the first substrate and the second substrate.

[0010] A seventh aspect of the present invention provides a substrate bonding method comprising forming a contact region in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact, and bonding the first substrate and the second substrate with the contact region formed in the center as the starting point for bonding, such that the contact region expands from the center, the method including a detection step of detecting that the contact region has been formed in the center, the detection step of detecting that the contact region has been formed in the center by detecting vibrations generated on one side of the first substrate and the second substrate on the other side of the first substrate and the second substrate.

[0011] In an eighth aspect of the present invention, a substrate bonding method is provided, in which a contact region is formed in the center of the first substrate and the second substrate where the first substrate and the second substrate are in contact, and the first substrate and the second substrate are bonded together, with the contact region formed in the center as the starting point for bonding, such that the contact region expands from the center, the method comprising: a determination step of determining whether a predetermined bonding force has been secured in the contact region; and a release step of releasing the holding of at least one of the first substrate and the second substrate in accordance with the determination that the bonding force has been secured in the determination step.

[0012] The above summary of the invention does not enumerate all of its features. Subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of the substrate bonding apparatus 100. [Figure 2] This is a schematic plan view of the substrate 210. [Figure 3] This is a flowchart showing the procedure for stacking the circuit boards 210. [Figure 4] This is a schematic cross-sectional view of a substrate holder 221 that holds the substrate 211. [Figure 5] This is a schematic cross-sectional view of a substrate holder 223 that holds the substrate 213. [Figure 6] This is a schematic cross-sectional view of the bonded portion 300. [Figure 7] This is a schematic cross-sectional view of the bonded portion 300. [Figure 8] This is a schematic cross-sectional view of the bonded portion 300. [Figure 9] This is a schematic cross-sectional view of the bonded portion 300. [Figure 10] This is a schematic diagram showing the state of substrates 211 and 213 during the bonding process. [Figure 11] This is a schematic cross-sectional view of the bonded portion 300. [Figure 12] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 13] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 14] It is a schematic diagram explaining the operation of detector 341. [Figure 15] It is a schematic diagram explaining the operation of detector 341. [Figure 16] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 17] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 18] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 19] It is a schematic diagram showing the states of substrates 211 and 213 in the bonding process. [Figure 20] It is a schematic diagram explaining another structure of detector 341. [Figure 21] It is a schematic diagram explaining the operation of detector 341. [Figure 22] It is a schematic diagram explaining the operation of detector 341. [Figure 23] It is a schematic diagram explaining the structure of observation unit 345. [Figure 24] It is a schematic diagram explaining another structure of detector 343. [Figure 25] It is a schematic diagram explaining the operation of detector 343. [Figure 26] It is a schematic diagram explaining the structure of observation unit 346. [Figure 27] It is a schematic diagram explaining the operation of observation unit 346. [Figure 28] It is a schematic diagram explaining the structure of observation unit 347. [Figure 29] It is a schematic diagram explaining the structure of observation unit 348. [Figure 30] It is a schematic diagram explaining the structure of observation unit 349. [Figure 31] It is a schematic diagram explaining the structure of observation unit 610. [Figure 32] This is a schematic diagram illustrating the structure of the observation unit 620. [Figure 33] This is a schematic cross-sectional view showing part of the structure of the bonded portion 300. [Figure 34] This is a flowchart showing part of the operation procedure of the bonding section 300. [Figure 35] This diagram shows the operation of the bonding section 300. [Figure 36] This diagram shows the operation of the bonding section 300. [Figure 37] This diagram shows the operation of the bonding section 300. [Figure 38] This diagram shows the operation of the bonding section 300. [Modes for carrying out the invention]

[0014] The present invention will be described below through embodiments of the invention. The embodiments described below are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0015] Figure 1 is a schematic plan view of the substrate bonding apparatus 100. The substrate bonding apparatus 100 comprises a housing 110, substrate cassettes 120, 130 and a control unit 150 located outside the housing 110, and a transport unit 140, bonding unit 300, holder stocker 400 and pre-aligner 500 located inside the housing 110. The inside of the housing 110 is temperature-controlled, for example, kept at room temperature.

[0016] One circuit board cassette 120 houses multiple circuit boards 210 that will be stacked. The other circuit board cassette 130 can house multiple bonded circuit boards 230 that have been made by stacking the circuit boards 210. Circuit board cassettes 120 and 130 can be individually attached to and detached from the housing 110. In this way, by using circuit board cassette 120, multiple circuit boards 210 can be loaded into the circuit board bonding apparatus 100 all at once. Also, by using circuit board cassette 130, multiple bonded circuit boards 230 can be unloaded from the circuit board bonding apparatus 100 all at once.

[0017] The transport unit 140 is responsible for transporting within the housing 110. The transport unit 140 transports individual substrates 210, substrate holders 220, substrate holders 220 holding substrates 210, laminated substrates 230 formed by stacking substrates 210, and the like.

[0018] The control unit 150 comprehensively controls and coordinates each part of the substrate bonding apparatus 100. The control unit 150 also receives user instructions from an external source and sets the manufacturing conditions for producing the bonded substrates 230. Furthermore, the control unit 150 has a user interface that displays the operating status of the substrate bonding apparatus 100 to the outside.

[0019] The bonding section 300 has a pair of opposing stages, each holding a substrate 210. Under the control of the control unit 150, the two substrates 210 held on the stages are aligned relative to each other and then brought into contact and bonded together. This forms a bonded substrate 230. Bonding includes a state in which terminals provided on each of the two substrates 210 are electrically connected to each other, and a state in which insulating films formed on the surfaces of the two substrates 210 are joined together and there is no electrical connection between the substrates 210. In either state, the two substrates 210 can be separated and cannot be separated. If the bonded state of the two substrates 210 is separable, it is preferable to transfer the substrates 210 to a heating device such as an annealing furnace and heat them after bonding.

[0020] The holder stocker 400 accommodates a plurality of substrate holders 220. Each substrate holder 220 is made of a hard material such as alumina ceramics and has a holding portion that adsorbs the substrate 210 and an edge portion located outside the holding portion. Inside the substrate bonding apparatus 100, each substrate holder 220 holds a substrate 210 and is handled integrally with the substrate 210. This ensures flatness for substrates 210 that are warped or bent.

[0021] When the bonded substrate 230 is removed from the substrate bonding apparatus 100, the substrate holder 220 is separated from the bonded substrate 230 and placed back into the holder stocker 400. This allows a small number of substrate holders 220 to be reused repeatedly. Therefore, the substrate holder 220 can be considered as part of the substrate bonding apparatus 100.

[0022] The pre-aligner 500 works in cooperation with the transport unit 140 to hold the substrate 210, which has been transported to the substrate bonding device 100, in the substrate holder 220. The pre-aligner 500 may also be used to separate the bonded substrate 230, which has been discharged from the bonding unit 300, from the substrate holder 220.

[0023] The substrate bonding apparatus 100 can bond not only substrates 210 on which elements, circuits, terminals, etc., are formed, but also unprocessed silicon wafers, compound semiconductor wafers, glass substrates, etc. Furthermore, it can bond circuit boards with circuits formed on them to unprocessed substrates, or bond circuit boards to each other, unprocessed substrates to each other, or other substrates of the same type. Moreover, the substrate 210 to be bonded may itself be a bonded substrate 230 that has already been formed by stacking multiple substrates.

[0024] Figure 2 is a schematic plan view of a substrate 210 that can be bonded in a substrate bonding apparatus 100. The substrate 210 has a notch 214, a plurality of circuit regions 216, and a plurality of alignment marks 218.

[0025] The notch 214 is formed on the periphery of the substrate 210, which is generally circular, and serves as an indicator of the crystal orientation on the substrate 210. Furthermore, when handling the substrate 210, the arrangement direction of the circuit regions 216 on the substrate 210 can be determined by detecting the position of the notch 214. Moreover, if a single substrate 210 has circuit regions 216 containing different circuits, the circuit regions 216 can be distinguished using the notch 214 as a reference.

[0026] The circuit regions 216 are arranged periodically on the surface of the substrate 210 in the planar direction of the substrate 210. Each of the circuit regions 216 is provided with semiconductor devices, wiring, protective films, etc., formed using photolithography technology or the like. The circuit regions 216 also include pads, bumps, etc., which serve as connection terminals when the substrate 210 is electrically connected to another substrate 210, lead frame, etc.

[0027] The alignment marks 218 are, for example, placed on top of scribe lines 212 placed between circuit regions 216, and are used as indicators when aligning substrate 210 with other substrates 210 to be stacked. Since the scribe lines 212 are areas that will ultimately be removed by dicing, the area of ​​the circuit region 216 is not reduced by providing the alignment marks 218. The alignment marks 218 may be placed inside the circuit region 216, or a part of a structure formed in the circuit region 216 may be used as the alignment marks 218.

[0028] Figure 3 is a flowchart showing the procedure for manufacturing a bonded substrate 230 by bonding substrates 210 in a substrate bonding apparatus 100. In the substrate bonding apparatus 100, the control unit 150 controls the operation of each part. The control unit 150 also functions as a determination unit that determines whether or not the bonding of substrates 210 is complete.

[0029] Inside the substrate bonding apparatus 100, the substrates 210 are operated one by one while being held in the substrate holder 220. Therefore, the control unit 150 first causes the pre-aligner 500 to hold the substrates 210, which have been removed from the substrate cassette 120, one by one in the substrate holder 220. Next, the control unit 150 loads the multiple substrates 210 to be bonded together, along with the substrate holder 220, into the bonding section 300 (step S101).

[0030] Next, the control unit 150 detects alignment marks 218 provided on each of the substrates 210 that have been fed into the bonding section 300 (step S102). The control unit 150 also detects the relative positions of the multiple substrates 210 to be bonded based on the positions of the detected alignment marks 218 (step S103).

[0031] Next, the control unit 150 activates the surface of the substrate 210 (step S104). The substrate 210 can be activated, for example, by exposing its surface to plasma for cleaning. This causes the substrates 210 to bond to each other and become one when they come into contact with other substrates 210. The substrate 210 can also be activated by mechanical treatments such as polishing, or by chemical treatments such as cleaning. In addition, multiple activation methods may be used in combination.

[0032] Next, the control unit 150 starts temperature control of the substrates 210 to be bonded (step S105). The temperature control performed here is, for example, temperature control to compensate for the magnification difference from the design specifications of the substrate 210. In addition, deformation such as warping of the substrate 210 may be corrected by methods other than temperature control, for example, by a correction method using an actuator described later. This makes it possible to accurately align multiple substrates 210 even if each substrate 210 has its own inherent distortion.

[0033] Next, the control unit 150 aligns the multiple substrates 210 to be bonded to each other (step S106). The alignment is performed by moving one substrate 210 relative to the other substrate 210 based on the relative positions of the substrates 210 detected in step S103.

[0034] Next, the control unit 150 brings parts of the overlapping substrates 210 into contact with each other in order to form a bonding starting point on a part of the substrate 210 (step S107). The parts that come into contact with each other are contact areas, which are regions where the substrates 210 are in contact with each other, and are contact areas formed when bonding begins. The starting point may be a region with an area. The bonding starting point in a pair of substrates 210 to be bonded is formed when a part of one substrate 210 is pressed against a part of the other substrate 210, thereby pushing out the atmosphere or other material sandwiched between the substrates 210, causing the substrates 210 to come into direct contact with each other. This contact causes the contact areas of the two activated substrates 210 to bond through chemical bonds such as hydrogen bonds. After partially bringing the two substrates 210 into contact, the two substrates 210 maintain contact with each other. At this time, the contact area may be expanded by pressing the substrates 210 together to increase the area of ​​the contact. After a predetermined time has elapsed while the contact state is maintained, a bonding force of a size sufficient to prevent misalignment between the two substrates 210 during the bonding process is secured between the two substrates 210. As a result, a bonding starting point is formed on the parts of the substrates 210 that are in contact with each other.

[0035] Furthermore, if multiple bonding starting points are formed in the planar direction of the substrate 210, air bubbles remaining in the region sandwiched between the multiple starting points cannot be expelled during the bonding process, which may result in voids in the final bonded substrate 230. Therefore, when bonding two substrates 210, it is preferable to form a bonding starting point at one location on each substrate 210 and bond the entire substrate 210 by expanding the contact region, which is the area where the substrates 210 are bonded together, from that bonding starting point.

[0036] Therefore, when bonding substrates 210 at the bonding portion 300, for example, a raised portion is formed on one of the substrates 210 to be bonded, and this raised portion is brought into contact with the other substrate 210, thereby forming a predetermined bonding starting point at one position. When forming a bonding starting point, it is preferable to maintain the shape of the raised portion on the substrate until the bonding starting point is formed, in order to prevent the formation of starting points in multiple locations.

[0037] Next, the control unit 150 checks whether a contact area has been formed between the two substrates 210, where parts of the substrates 210 are pressed against each other, and whether a predetermined bonding force of the above-mentioned size has been secured between the two substrates 210 (step S108). If it is detected at this stage that the substrates 210 have been bonded together, it checks whether a bonding starting point has been formed, which will trigger the start of bonding of the substrates 210. Therefore, in step S108, it checks whether a bonding starting point area has been formed in the area where parts of the substrates 210 were pressed together in step S107, or at a position close to that area.

[0038] If it is determined that a bonding starting point has been formed on the substrate 210 (step S108: YES), that is, if the control unit 150 determines that a bonding force of the predetermined size described above has been secured between the contacted parts of the two substrates 210, it releases the hold on at least one of the substrates 210 and frees that substrate 210 (step S109), thereby widening the contact area of ​​the two substrates 210 and allowing them to attract and bond to each other. In other words, the bonding portion 300 constitutes the contact portion. If it is not confirmed in step S108 that a bonding starting point has been formed on the substrate 210 (step S108: NO), the control unit 150 continues to hold both substrates 210 and continues to press a part of the substrate 210 in order to form a bonding starting point.

[0039] Next, the control unit 150 checks whether the contact area of ​​the substrate 210 has expanded from the bonding starting point formed on the substrate 210 (step S110). Whether the contact area of ​​the substrate 210 has expanded can be confirmed, for example, by checking whether a contact area has been formed in a region different from the region where the bonding starting point was formed.

[0040] If, in step S110, it is not confirmed that the contact area of ​​the substrate 210 has expanded (step S110: NO), the control unit 150 determines that the bonding of the substrate 210 is being hindered for some reason. Therefore, it takes action such as stopping the operation of the bonding unit 300, sending an alarm to the outside, or removing the substrate 210 being bonded from the bonding unit 300 (step S111), and then returns control to step S101 to start bonding the next substrate 210.

[0041] If it is confirmed in step S110 that the contact area of ​​the substrate 210 has expanded (step S110: YES), the control unit 150 determines that the bonding of the substrate 210 is progressing and proceeds to the next step. Next, the control unit 150 checks whether the bonding of the substrate 210 is complete (step S112). Completion of bonding can be determined, for example, by checking whether the contact area of ​​the substrate 210 has been formed on the outer edge of the substrate 210. This allows the control unit 150 to reliably confirm the completion of bonding even if the time required for bonding differs for each substrate 210.

[0042] If the control unit 150 confirms in step S112 that the bonding of the substrates is complete (step S112: YES), it terminates temperature control and other operations for the substrates 211 and 213, and has the bonded substrate 230 removed from the bonding unit 300 by the transport unit 140 (step S113). The substrate 210 removed from the bonding unit 300 is separated into the bonded substrate 230 and the substrate holder 220, and then stored in the substrate cassette 130.

[0043] Furthermore, if the control unit 150 cannot confirm that the bonding of the substrates is complete in step S112 (step S112: NO), it may repeatedly check for completion of the bonding of the substrate 210 until completion of the bonding of the substrate 210 is confirmed. However, if completion of the bonding of the substrate 210 cannot be confirmed even after a predetermined threshold time has elapsed, the control unit 150 may stop bonding the substrate 210, as in the case of step S110: NO.

[0044] Furthermore, when the control unit 150 confirms that the contact area of ​​the substrate 210 has expanded in step S110, it may also detect the speed at which the contact area of ​​the substrate 210 expands, thereby predicting the time it will take for the substrate 210 to be bonded. The speed at which the contact area of ​​the substrate 210 expands may be calculated by the control unit, for example, by measuring the time from when a part of the substrate 210 is pressed in step S107 until when it is detected in step S110 that the substrate 210 has been bonded in a region different from the starting point of bonding.

[0045] Furthermore, once a bonding starting point is formed on a portion of the substrate 210, the relative positions of the multiple substrates 210 to be bonded are fixed in the planar direction of the substrates 210. Even if the holding of at least one of the substrates 210 to be bonded is released, the substrates 210 will not be displaced, nor will one substrate 210 become misaligned with respect to the other. Therefore, the control unit 150 may remove the two substrates 210 from the bonding section 300 before the bonding of the substrates 210 is completed to the periphery.

[0046] Figure 4 is a schematic cross-section showing a single substrate 211 being carried into the bonding section 300 in step S101 and held by the substrate holder 221. The substrate holder 221 has an electrostatic chuck, a vacuum chuck, etc., which attracts and holds the substrate 211 to the holding surface 222.

[0047] The holding surface 222 of the substrate holder 221 has a curved shape that is higher in the center and lower at the periphery. Therefore, the substrate 211 that is adsorbed to the holding surface 222 also curves into a shape with a protruding center. Furthermore, the convex shape of the substrate 210 is maintained as long as the substrate holder 221 continues to hold the substrate 211. Note that the shape of the holding surface 222 of the substrate holder 221 may be a sphere, parabolic surface, cylindrical surface, etc.

[0048] When the substrate 211 is adsorbed onto the holding surface 222, in the case of a curved substrate 211, the surface of the substrate 211 expands in the planar direction compared to the center line A in the thickness direction of the substrate 211, which is shown as a dashed line in the figure. On the other hand, the surface of the substrate 211 contracts in the planar direction on the lower surface of the substrate 211.

[0049] Therefore, by holding the substrate 211 in the substrate holder 221, the in-plane magnification of the circuit region 216 formed on the surface of the substrate 211 relative to the design specifications is also increased. Thus, the magnification correction amount of the substrate 211 may be adjusted by preparing multiple substrate holders 221 with different curvatures of the holding surface 222 and changing the amount of deformation of the substrate 211.

[0050] Furthermore, the substrate holder 221 has a plurality of observation holes 227, 228, and 229 that penetrate in the thickness direction. One observation hole 227 is located in a region including the central axis X in the radial direction of the substrate holder 221. Another observation hole 229 is located in a region including the periphery of the substrate 211 held by the substrate holder 221. Yet another observation hole 228 is located at an intermediate position between the other observation holes 227 and 228. Each of the observation holes 227, 228, and 229 is filled with a material that is transparent to the wavelength of the illumination light used when observing the substrate 211, and the holding surface 222 of the substrate holder 221 forms a smooth curved surface.

[0051] Figure 5 is a schematic cross-section showing another substrate 213 held in the substrate holder 223. The substrate holder 223 has a flat holding surface 224 and a function for attracting the substrate 213, such as an electrostatic chuck or a vacuum chuck. The substrate 213 that is attracted and held in the substrate holder 223 adheres closely to the holding surface 224 and becomes flat, conforming to the shape of the holding surface 224.

[0052] Therefore, in the bonding portion 300, when the substrate 211, which is held in a convex shape by the substrate holder 221 shown in Figure 4, is pressed against the substrate 213, which is held in a flat state by the substrate holder 223 shown in Figure 5, the substrates 211 and 213 are pressed firmly at a single point in the center. Furthermore, while the substrate holders 221 and 223 each hold the substrates 211 and 213, the peripheral regions of the substrates 211 and 213 remain separated from each other.

[0053] In the above example, a combination of a convexly deformed substrate 211 and a flat substrate 213 was used as an example. However, even if both substrates 211 and 213 are deformed into a convex shape, if substrates 211 and 213 are deformed into a convex and concave shape with different curvatures, or if substrates 211 and 213 are deformed into a cylindrical shape with non-equipped central axes, the substrates 211 and 213 can be brought into contact at a single point in the bonding portion 300.

[0054] Figure 6 is a schematic cross-sectional view showing the structure of the bonding section 300. Figure 6 also shows the state of the bonding section 300 immediately after the substrates 211, 213 and substrate holders 221, 223 are loaded. The bonding section 300 comprises a frame 310, an upper stage 322, and a lower stage 332.

[0055] The frame 310 has a base plate 312 and a top plate 316 that are parallel to the horizontal floor surface, and a plurality of support columns 314 that are perpendicular to the floor plate. The base plate 312, support columns 314 and top plate 316 form a rectangular frame 310 that accommodates the other members of the bonded section 300.

[0056] The upper stage 322 is fixed downwards to the lower surface of the top plate 316 in the figure. The upper stage 322 has a holding function such as a vacuum chuck or an electrostatic chuck and forms a holding part for holding the substrate holder 221. In the illustrated state, the substrate holder 221, which already holds the substrate 211, is already held in the upper stage 322.

[0057] Furthermore, the upper stage 322 has a plurality of observation windows 327, 328, and 329 provided corresponding to the positions of the observation holes 227, 228, and 229 of the held substrate holder 221. Each of the observation windows 327, 328, and 329 is filled with a material that is transparent to the wavelength of the illumination light used when observing the substrate 211, and the lower surface of the upper stage 322 forms a flat surface, including the area where the observation windows 327, 328, and 329 are located.

[0058] The bonding section 300 has a plurality of detectors 341, 342, and 343 that penetrate the top plate 316 of the frame 310 in the thickness direction, at positions corresponding to the observation windows 327, 328, and 329 provided on the upper stage 322. The detectors 341, 342, and 343 form an observation section 344 for observing the bonding state of the substrates 211 and 213 within the bonding section 300, through the observation windows 327, 328, and 329 that optically communicate with the lower surface of the upper stage 322 and the observation holes 227, 228, and 229 of the substrate holder 221.

[0059] Detectors 341, 342, and 343 can be formed, for example, using a light-receiving unit such as a photodiode and an illumination light source. In this case, when a substrate holder 221 holding the substrate 211 is held on the upper stage 322, the light intensity of the reflected light from the substrates 211, 213, etc. can be observed by detectors 341, 342, and 343 through observation windows 327, 328, and 329 and observation holes 227, 228, and 229.

[0060] Furthermore, detectors 341, 342, and 343 can be formed using, for example, an image sensor such as a CCD or CMOS sensor and an illumination light source. In this case, when the substrate holder 221 holding the substrate 211 is held on the upper stage 322, an image of the substrate 211 on the upper stage 322 can be captured and observed by the detectors 341, 342, and 343 through the observation windows 327, 328, and 329 and the observation holes 227, 228, and 229. Also, if the substrates 211 and 213 overlap in the bonding portion 300, the substrates 211 and 213 can be imaged together.

[0061] Furthermore, by using long-wavelength light such as infrared light as an illumination or light source, the detectors 341, 342, and 343 can see through the substrate 211 held on the upper stage 322 and observe the substrate 213 being bonded to the substrate 211. The outputs of the detectors 341, 342, and 343 are processed, for example, in the control unit 150, and the bonding of the substrates 211 and 213 is detected based on the observation results of the detectors 341, 342, and 343. When infrared light is used as the illumination light source, the change in the position of the boundary between the contact area and the non-contact area of ​​the substrates 211 and 213 may be observed by photographing the area including the center of the substrates 211 and 213. In this case, the shape of the contact area is detected at the time when the starting point of bonding is formed, or during the process of the contact area expanding. The shape of the contact area is one piece of information regarding the state of expansion of the contact area. That is, the observation unit 344 constitutes a detection unit that detects information regarding the expansion of the contact area. Information regarding the expansion of the contact area is information that changes according to the degree of expansion of the contact area. If the control unit 150 determines that the shape of the contact area satisfies predetermined conditions, it may determine that the contact state of the contact area is in a state where bonding will be performed appropriately thereafter, and the substrates 211 and 213 may be discharged from the lower stage 332. The predetermined conditions are, for example, that the shape of the contact area is approximately a perfect circle. The shapes of the contact area that satisfy the predetermined conditions are stored in advance. Furthermore, if the shape of the contact area is unique to each wafer type, lot, and wafer manufacturing process, the shape of each contact area during expansion may be stored in the memory unit in advance and compared with the stored shape during actual bonding. Furthermore, when infrared light is used as the illumination source, the observation area may be a region extending radially from at least the center to the periphery of the substrates 211 and 213. In this case, as the contact area expands, multiple images can be taken consecutively, for example, at 500 msec intervals, and by comparing the image of the contact area taken at a certain point in time with the image of the contact area taken at a previous point in time, the direction and speed of progression as the contact area expands can be estimated.

[0062] The lower stage 332 is positioned opposite the upper stage 322 and is mounted on the upper surface in the figure of the Y-direction drive unit 333, which is superimposed on the X-direction drive unit 331 located on the upper surface of the bottom plate 312. The lower stage 332 faces the substrate 211 held by the upper stage 322 and forms a holding portion for holding the substrate 213. In the illustrated state, the lower stage 332 already holds a substrate holder 223 that holds the substrate 213.

[0063] In the illustrated configuration, a substrate holder 221 with a curved holding surface 222 is held on the upper stage 322 located at the top of the figure, and a substrate 213 held by a substrate holder 223 with a flat holding surface 224 is held on the lower stage 332 located at the bottom of the figure. However, the combination of the upper stage 322 and lower stage 332 with the substrate holders 221 and 223 is not limited to this. Furthermore, a flat substrate holder 223 or a curved substrate holder 221 may be loaded into both the upper stage 322 and the lower stage 332.

[0064] In the bonding section 300, the X-direction drive unit 331 moves parallel to the bottom plate 312 in the direction indicated by arrow X in the figure. The Y-direction drive unit 333 moves on the X-direction drive unit 331, parallel to the bottom plate 312, in the direction indicated by arrow Y in the figure. By combining the movements of the X-direction drive unit 331 and the Y-direction drive unit 333, the lower stage 332 moves two-dimensionally parallel to the bottom plate 312. This allows the substrate 213 mounted on the lower stage 332 to be aligned with the substrate 211 held on the upper stage 322.

[0065] Furthermore, the lower stage 332 is supported by a lifting drive unit 338 that moves up and down perpendicular to the bottom plate 312 in the direction indicated by arrow Z. The lower stage 332 can move up and down relative to the Y-direction drive unit 333. As a result, the lifting drive unit 338 forms a pressing portion that presses the substrate 213 mounted on the lower stage 332 against the substrate 211 held on the upper stage 322.

[0066] The amount of movement of the lower stage 332 by the X-direction drive unit 331, the Y-direction drive unit 333, and the lifting drive unit 338 is precisely measured using an interferometer or the like. Furthermore, the X-direction drive unit 331 and the Y-direction drive unit 333 may have a two-stage configuration consisting of a coarse movement unit and a fine movement unit. This allows for both high-precision alignment and high throughput, enabling high-speed bonding of the substrate 213 mounted on the lower stage 332 without reducing control accuracy.

[0067] The Y-direction drive unit 333 is further equipped with a microscope 334 and an activation device 336, both mounted to the sides of the lower stage 332. The microscope 334 can observe the underside of the downward-facing substrate 211 held on the upper stage 322. The activation device 336 generates plasma to clean the underside of the substrate 211 held on the upper stage 322.

[0068] The bonding section 300 may further include a rotation drive unit that rotates the lower stage 332 around a rotation axis perpendicular to the bottom plate 312, and a swing drive unit that swings the lower stage 332. This makes the lower stage 332 parallel to the upper stage 322 and rotates the substrate 213 held on the lower stage 332, thereby improving the alignment accuracy of the substrates 211 and 213.

[0069] Furthermore, the bonding section 300 includes a pair of microscopes 324, 334 and a pair of activation devices 326, 336. One microscope 324 and one activation device 326 are fixed to the side of the upper stage 322 on the underside of the top plate 316. The microscope 324 can observe the upper surface of the substrate 213 held on the lower stage 332. The activation device 326 generates plasma to clean the upper surface of the substrate 213 held on the lower stage 332.

[0070] Furthermore, the other microscope 334 and activation device 336 are mounted to the side of the lower stage 332 in the Y-direction drive unit 333. The microscope 334 can observe the underside of the substrate 211 held on the upper stage 322. The activation device 336 generates plasma to clean the underside of the substrate 211 held on the upper stage 322.

[0071] Microscopes 324 and 334 can be used in step S102 in the following procedure. The control unit 150 calibrates the relative positions of microscopes 324 and 334 by aligning their focal points with each other, as shown in Figure 6.

[0072] Next, as shown in Figure 7, the control unit 150 operates the X-direction drive unit 331 and the Y-direction drive unit 333 to cause the microscopes 324 and 334 to detect the alignment marks 218 provided on the substrates 211 and 213, respectively (step S102 in Figure 3). The control unit 150 keeps track of the amount of movement of the lower stage 332 by the X-direction drive unit 331 and the Y-direction drive unit 333 until the alignment marks 218 are detected.

[0073] Thus, by detecting the positions of the alignment marks 218 on substrates 211 and 213 with microscopes 324 and 334 whose relative positions are known, the relative positions of substrates 211 and 213 can be determined (step S103 in Figure 3). Therefore, when aligning substrates 211 and 213 to be superimposed, the relative movement amount, including the relative movement and rotation amount of substrates 211 and 213, should be calculated in order to match the positions of the detected alignment marks 218.

[0074] However, individual substrates 211 and 213 forming the bonded substrate 230 may experience individual strains. Strains occurring in substrates 211 and 213 include warping and bending of substrates 211 and 213, which have a consistent tendency throughout the substrates 211 and 213, and nonlinear strains that occur in the planar or radial direction of the substrates.

[0075] These strains are caused by stress generated during the process of forming the circuit regions 216 on substrates 211 and 213, anisotropy due to the crystal orientation of substrates 211 and 213, and periodic changes in stiffness due to the arrangement of scribe lines 212, circuit regions 216, etc. Furthermore, even if no strain occurs in substrates 211 and 213 individually, during the bonding process, substrates 211 and 213 may deform and generate strain at the boundary between the contact region (an already bonded area) and the non-contact region (an area that has not yet been bonded).

[0076] If substrates 211 and 213 each have different individual distortions, even if the relative displacement is calculated in step S106, it may not be possible to calculate a value that will result in the alignment marks 218 being in the same position. Therefore, the distortion of at least one of substrates 211 and 213 can be corrected by temperature control (step S105) to improve the alignment accuracy of substrates 211 and 213.

[0077] For example, distortion caused by differences in the magnification of the circuit region 216 on substrates 211 and 213 relative to the design specifications can be corrected by changing the overall size of substrates 211 and 213 by adjusting the temperature of at least one of the substrates 211 and 213. Also, as already explained, distortion of substrate 211 can be corrected by holding substrate 211 in a substrate holder 221 whose holding surface 222 is curved or bent.

[0078] Furthermore, in the bonding section 300, an actuator that mechanically deforms the substrates 211 and 213 can be provided on at least one of the upper stage 322 and lower stage 332 on which the substrates 211 and 213 are mounted, thereby correcting the deformation of at least one of the substrates 211 and 213. This allows the bonding section 300 to correct the distortion of the substrates 211 and 213, whether linear or nonlinear.

[0079] Figure 8 shows the operation in which the bonding section 300 activates the substrates 211 and 213 (step S104 in Figure 3). The control unit 150 resets the position of the lower stage 332 to its initial position and then moves it horizontally, causing the plasma generated by the activation devices 326 and 336 to scan the surfaces of the substrates 211 and 213. As a result, the surfaces of the substrates 211 and 213 are cleaned and their chemical activity is increased. Therefore, the substrates 211 and 213 autonomously attract and bond to each other simply by coming close together.

[0080] Furthermore, the activation devices 326 and 336 emit plasma P in a direction away from the microscopes 324 and 334, respectively. This prevents fragments generated from the plasma-irradiated substrates 211 and 213 from contaminating the microscope 324.

[0081] Furthermore, although the bonding section 300 is equipped with activation devices 326, 326 for activating the substrates 211, 213, it is also possible to omit the activation devices 326 in the bonding section 300 by transporting the substrates 211, 213, which have been pre-activated using activation devices 326, 326 provided separately from the bonding section 300, into the bonding section 300.

[0082] Furthermore, in addition to exposure to plasma, substrates 211 and 213 can also be activated by sputter etching using an inert gas, an ion beam, or a fast atomic beam. When using an ion beam or a fast atomic beam, the bonded portion 300 can be formed under reduced pressure. Substrates 211 and 213 can also be activated by ultraviolet irradiation, an ozone asher, or the like. Furthermore, they may be activated by chemically cleaning the surface of substrates 211 and 213 using, for example, a liquid or gaseous etchant.

[0083] Note that the order of step S104, which activates at least one of substrates 211 and 213, and step S105, which temperature-controls either substrate 211 or 213, may be reversed. That is, as described above, substrates 211 and 213 may be activated (step S104) and then temperature-controlled (step S105) at least one of substrates 211 or 213, or at least one of substrates 211 or 213 may be temperature-controlled first (step S105) and then activated (step S104).

[0084] Figure 9 shows the operation of the bonding section 300 to align the substrates 211 and 213 (step S106 in Figure 3). The control unit 150 first moves the lower stage 332 so that the amount of misalignment between the substrates 211 and 213 becomes smaller than a predetermined value, based on the relative positions of the microscopes 324 and 334 detected initially and the positions of the alignment marks 218 on the substrates 211 and 213 detected in step S102.

[0085] Figure 10 schematically shows the state of substrates 211 and 213 in step S106 shown in Figure 9. As shown in the figure, substrates 211 and 213, which are held on the upper stage 322 and lower stage 332 respectively via substrate holders 221 and 223, face each other in an aligned state.

[0086] As explained earlier, the substrate holder 221 held on the upper stage 322 holds the substrate 211 with a holding surface 222 that is raised in the center, so the substrate 211 also has a raised center. On the other hand, the substrate holder 223 held on the lower stage 332 has a flat holding surface 224, so the substrate 213 is held in a flat state. Therefore, the distance between the opposing substrates 211 and 213 in the bonding portion 300 is close in the center and becomes further away as it approaches the periphery.

[0087] Figure 11 shows the operation (step S107 in Figure 3) in which the bonding portion 300 brings the substrate 213 held on the lower stage 332 into contact with the substrate 211 held on the upper stage 322. The control unit 150 operates the lifting drive unit 338 to raise the lower stage 332, thereby bringing the substrates 211 and 213 into contact with each other.

[0088] Figure 12 is a schematic diagram showing the state of substrates 211 and 213 from step S107 to step S108 shown in Figure 10. As shown in the figure, the central part of substrate 211 held by the upper stage 322 is raised, so when the lower stage 332 approaches the upper stage 322, the central parts of substrates 211 and 213 first come into contact. Furthermore, as the control unit 150 continues the operation of the lifting drive unit 338, the central parts of substrates 211 and 213 come into contact with each other, and a starting point for bonding is formed on substrates 211 and 213.

[0089] At this point, the substrate 211 is still held by the curved holding surface 222 of the substrate holder 221. Therefore, when the central portion of the substrate 211 comes into contact with the flat substrate 213, the peripheral portion of the substrate 211 is held by the substrate holder 221 and separated from the substrate 213. In other words, the substrate holder 221 continues to hold the substrate 211 in such a way that parts other than the central portions of the substrates 211 and 213 do not come into contact with each other.

[0090] Furthermore, it is preferable to correct the substrates 211 and 213 by creating a temperature difference through temperature control or the like before the bonding starting point described above is formed. This makes it possible to manufacture a bonded substrate 230 in which the positional misalignment of the central parts of substrates 211 and 213 is reduced.

[0091] Figure 13 shows the state of substrates 211 and 213 during the period following step S107 shown in Figure 3. In step S107, substrates 211 and 213 are pressed together in a portion of their central plane. This creates a bonding starting point 231 near the center of substrates 211 and 213, where the substrates 211 and 213 are partially bonded. However, as explained with reference to Figure 12, since substrate 211 is still held by the substrate holder 221, the areas of substrates 211 and 213 away from the center are not yet bonded.

[0092] Figure 14 is a partially enlarged view showing the state immediately before substrates 211 and 213 make contact during the execution of step S107 (see Figure 3). The area shown in Figure 14 corresponds to the area indicated by the dotted line B in Figure 12.

[0093] In the illustrated state, a gap G remains between the substrates 211 and 213. The gap G is formed when the atmosphere inside the bonding portion 300 is trapped between the substrates 211 and 213. The atmosphere trapped between the substrates is pushed out as the bonding portion 300 continuously presses against the substrates 211 and 213, and eventually the substrates 211 and 213 become tightly bonded to each other. However, the time required for the substrates 211 and 213 to bond may vary depending on the density of the atmosphere, etc.

[0094] In the bonded portion 300, even when the substrates 211 and 213 are sandwiched between the upper stage 322 and the lower stage 332, a portion of the central part of the substrates 211 and 213 is optically connected to the detector 341 through the observation window 327 and the observation hole 227. In the illustrated example, the detector 341 has a light source 351 and a light receiving unit 352.

[0095] The light source 351 generates illumination light of a wavelength that at least a portion of it penetrates the substrate 211. The illumination light generated by the light source 351 is shone toward the substrate 211 through the observation window 327 and the observation hole 227. The light receiving unit 352 has a photoelectric conversion element such as a photodiode and receives the illumination light reflected by the substrate 211, 213, etc., and generates an electrical signal corresponding to the reflected light intensity. The electrical signal generated by the light receiving unit 352 is input to the control unit 150.

[0096] As shown by the dashed line in the figure, a reflective surface is formed at the boundary between the upper stage 322 and the lower stage 332, where the media have different refractive indices. In the illustrated example, reflective surfaces P, Q, R, and S are formed at the boundary between the observation hole 227 and the substrate 213, the boundary between the substrate 213 and the gap G, the boundary between the gap G and the substrate 213, and the boundary between the substrate 213 and the substrate holder 221, respectively. Therefore, the illumination light irradiated from the light source 351 of the detector 341 through the observation window 327 and the observation hole 227 is reflected at each of the reflective surfaces P, Q, R, and S, and the intensity of the reflected light is detected by the light receiving section 352 of the detector 341.

[0097] Figure 15 shows the state after step S107, where the centers of substrates 211 and 213 are bonded together, from the same viewpoint as Figure 14. When substrates 211 and 213 are bonded together and in close contact with each other, the pair of reflective surfaces R and Q formed between substrates 211 and 213 and the gap G disappear. As a result, the number of reflective surfaces that reflect the light irradiated by the detector 341 decreases, and the reflected light intensity detected by the detector 341 changes. That is, the overall reflectance from substrates 211 and 213 changes according to the size of the gap G; for example, the larger the size of the gap G, the greater the reflectance. The reflected light intensity is one piece of information regarding the state of the expansion of the contact area, and the brightness of the reflected light (cd / m²) is also a factor. 2) may be the luminous intensity of the reflected light (lm·s). Therefore, the control unit 150, upon receiving the output of the detector 341, can determine that the contact portion of the substrates 211 and 213, i.e., the bonding starting point 231, has been formed on the substrates 211 and 213, by detecting that the reflected light intensity has become constant or that the rate of change of the reflected light intensity has become smaller than a predetermined value. In other words, the control unit 150 determines that the contact state of the contact area is the state in which the starting point 231 has been formed. Therefore, the control unit 150 can form a determination unit that determines whether or not the substrates 211 and 213 have been bonded together.

[0098] The control unit 150 may release the substrate 211 (step S109 in Figure 3) in response to determining that the bonding starting point 231 has been formed. Through this series of controls, the bonding starting point 231 is reliably formed on the substrates 211 and 213, and the substrate 211 can be released without any unnecessary waiting time after the bonding starting point 231 has been formed. As a result, the yield and throughput of the bonded substrate 230 are improved.

[0099] In Figures 14 and 15, the illumination light is depicted as being tilted relative to the substrates 211 and 213 for the purpose of making it easier to distinguish between the illuminated light and the reflected light. However, even if the illumination light is shone perpendicularly to the substrates 211 and 213, an optical system for detecting the reflected light intensity can be formed by using an optical device such as a half-mirror. Furthermore, the detector 341 may use an image sensor such as a CCD or CMOS sensor instead of the light receiving unit 352. The above structure of the detector 341 can also be applied to the other detectors 342 and 343 shown in Figure 6, etc.

[0100] Figure 16 is a schematic plan view showing the state of substrates 211 and 213 during the period following step S109 (see Figure 3). Figure 17 is a schematic longitudinal cross-sectional view of substrates 211 and 213 in the state shown in Figure 16.

[0101] In step S109, the substrate 211 is released from the substrate holder 221 held by the upper stage 322. Since at least one surface of substrates 211 and 213 is activated, a portion of it adheres to form a bonding starting point. When one of the substrates 211 and 213 is released from the substrate holder 221 and 223, the intermolecular forces between the substrates 211 and 213 cause adjacent regions to autonomously attract and bond to each other. The contact area of ​​substrates 211 and 213 gradually expands to adjacent regions over time.

[0102] As a result, the bonding wave 232, which is the boundary between the contact region (where substrates 211 and 213 are bonded) and the non-contact region (where they are not yet bonded), moves radially from the inside to the outside of substrates 211 and 213, and the bonding of substrates 211 and 213 progresses. In other words, the contact region expands as the bonding wave moves. However, in the region outside the area surrounded by the bonding wave 232, substrates 211 and 213 are not yet bonded.

[0103] As previously explained, the substrate holder 221, which is held on the upper stage 322 of the bonding section 300, also has an observation hole 228 at a position midway between the center and the periphery of the substrate 211 it holds. Furthermore, the upper stage of the bonding section 300 has an observation window 328 and a detector 342 at positions corresponding to the observation hole 228 when the substrate holder 221 is held.

[0104] Therefore, when bonding substrates 211 and 213 at the bonding section 300, it is possible to determine whether or not the substrates 211 and 213 have been bonded, even at the position of the observation hole 228. The detector 342 can be the same structure as the detector 341 located in the center of the substrates 211 and 213, but is not limited to that.

[0105] In step S108, if the bonding starting point 231 is detected to have been formed at the center of the substrates 211 and 213, and the bonding of the substrates 211 and 213 is detected through the observation hole 228, the control unit 150 can determine in step S110 that the contact area of ​​the substrates 211 and 213 has expanded to the midpoint between the center and the periphery of the substrates 211 and 213 (step S110: YES). That is, it determines that the bonding wave has reached a predetermined intermediate position. The position of the bonding wave is one piece of information regarding the state of the expansion of the contact area. As a result, the control unit 150 can proceed to step S112 of the control procedure.

[0106] Furthermore, the substrate holder 221 also has observation holes 229 on the periphery of the substrate 211 it holds. In addition, the upper stage of the bonding section 300 has an observation window 329 and a detector 343 at positions corresponding to the observation holes 229 when the substrate holder 221 is held. Therefore, when bonding substrates 211 and 213 in the bonding section 300, it is possible to determine whether or not the substrates 211 and 213 have been bonded, even at the position of the observation holes 229.

[0107] In the state shown in Figures 16 and 17, substrates 211 and 213 are bonded at the observation hole 228, but not yet bonded at the observation hole 229. Therefore, the control unit 150 can determine that although the bonding wave 232 is expanding and the bonding of substrates 211 and 213 is progressing, the entire substrates 211 and 213 have not yet been bonded.

[0108] Figure 18 is a schematic plan view showing the state of substrates 211 and 213 at the point in step S112 (see Figure 3) when the control unit 150 determines that the bonding of substrates 211 and 213 is complete (step S112: YES). Figure 19 is a schematic longitudinal cross-sectional view of substrates 211 and 213 in the state shown in Figure 18.

[0109] In step S110, the control unit 150 confirmed through the observation hole 228, observation window 328, and detector 342 that the bonding of substrates 211 and 213 was progressing. As the bonding of substrates 211 and 213 progressed further, and the bonding wave 232 reached the periphery of substrates 211 and 213, the contact area extended to the entire substrates 211 and 213. As a result, substrates 211 and 213 were bonded together to form a bonded substrate 230.

[0110] As already explained, the substrate holder 221 held on the upper stage 322 of the bonding section 300 also has an observation hole 229 at the periphery of the substrate 211 it holds. Furthermore, the upper stage of the bonding section 300 has an observation window 329 and a detector 343 at positions corresponding to the observation hole 229 when the substrate holder 221 is held. Therefore, when bonding substrates 211 and 213 in the bonding section 300, it is possible to determine whether or not the substrates 211 and 213 have been bonded, even at the position of the observation hole 229.

[0111] In the bonded portion 300, in step S110, after the expansion of the contact area of ​​the substrates 211 and 213, surrounded by the bonding wave 232 which is the boundary between the contact area and the non-contact area, is detected (step S110: YES), it is possible to detect through the observation hole 229 whether or not the bonding wave has reached the outer edge of the substrates 211 and 213, that is, whether or not bonding is complete (step S112). Note that the detector 342 can be the same structure as the detector 341 located in the center of the substrates 211 and 213, but is not limited to that. In particular, the peripheral edges of the substrates 211 and 213 remain exposed to the outside even after the substrates 211 and 213 are bonded together. Therefore, the detector 343 that detects bonding at the peripheral edges of the substrates 211 and 213 can have a different structure from the other detectors 341 and 342.

[0112] Thus, in the bonded portion 300, the expansion of the contact area between the substrates 211 and 213 expands from the center of the substrates 211 and 213 toward the outer edge. Therefore, the atmosphere, such as air, that was sandwiched between the substrates 211 and 213 before bonding is pushed out from the inside to the outside of the substrates 211 and 213 as the contact area expands, preventing air bubbles from remaining between the bonded substrates 211 and 213.

[0113] In order to smoothly push out air bubbles and the like from between substrates 211 and 213 during the process of overlapping substrates 211 and 213, it is preferable that, at the time contact between substrates 211 and 213 begins, there is a gap between substrates 211 and 213 that is wide enough not to hinder the movement of air bubbles, and that a continuous gap is formed at the periphery of substrates 211 and 213. Therefore, when deformation of substrate 211 is caused by adsorption to the substrate holder 221 with a curved holding surface 222, it is preferable to select a deformation procedure that leaves a certain degree of curvature at the stage of contact with substrate 213 in step S107 (Figure 3). Also, if it is predicted that the curvature of substrate 211 will decrease during the overlapping stage, a substrate holder 223 with a curved holding surface 224, similar to substrate holder 221, may be used as the substrate holder 223 that holds the substrate 213 held on the lower stage 332, in order to secure a gap for air bubbles to pass through.

[0114] In the example above, step S109 released the substrate 211 held by the upper stage 322. However, in the same step, the lower stage 332 may release the substrate, or both stages may release the substrates 211 and 213.

[0115] However, when the substrate 211 is released from its hold, the correction of distortion caused by the substrate holder 221's suction is also released. Therefore, when releasing the substrate in step S109, it is preferable to release the substrate 211 or 213 that has relatively less deformation and therefore requires less correction.

[0116] Figure 20 is a schematic diagram illustrating another structure of the detector 341 in the bonded portion 300. Figure 20 is drawn from the same viewpoint as Figures 14 and 15.

[0117] In the bonded section 300, the illustrated detector 341 has a displacement meter 353. The displacement meter 353 has a fixed relative position to the upper stage 322, and detects the displacement of the substrates 211, 213, etc., which are the objects to be measured, by changes in their optical properties. Various types of optical displacement meters 353 can be used, but examples include triangulation type, laser focus type, and spectral interferometry type.

[0118] The illustrated detector 341 continuously measures the relative distance H1 between the upper surface of the upper substrate 211 and the upper surface of the lower substrate 213 in the figure, and in step S107 (see Figure 3), brings the substrates 211 and 213 closer together and eventually presses them against each other. During this process, when the value of the distance H1 becomes equal to the known thickness T1 of the upper substrate 211, it is detected that the substrates 211 and 213 are in contact without any gaps and are bonded together. In this way, by using a displacement meter 353 as the detector 341, the control unit 150 can continuously observe the bonding of the substrates 211 and 213 and reflect this in the control of the bonding section 300. The value of the distance H1 is one piece of information regarding the state of expansion of the contact area.

[0119] Figure 21 has the same structure as the bonding section 300 shown in Figure 20, but the object measured by the displacement meter 353 as the detector 341 is different. In the bonded section 300 shown in the figure, the displacement meter 353 measures the distance H2 between the position of the upper surface of the upper substrate 211 in the figure and the position of the lower surface of the lower substrate 213 in the figure, or the position of the upper surface of the lower substrate holder 221. Then, in step S107 (see Figure 3), the substrates 211 and 213 are brought close together and eventually pressed together. During this process, when the value of the distance H2 becomes equal to the sum of the known thickness T1 of the substrate 211 and the thickness T2 of the substrate 213, it can be detected that the substrates 211 and 213 are in contact without gaps and have been bonded together.

[0120] Figure 22 has the same structure as the bonded portion 300 shown in Figures 20 and 21, but the object measured by the displacement meter 353, which acts as the detector 341, is different. In the bonded portion 300 shown, the displacement meter 353 measures the thickness T3 of the gap G between substrates 211 and 213 based on the position of the lower surface of the upper substrate 211 in the figure and the position of the upper surface of the lower substrate 213 in the figure. Then, in step S107 (see Figure 3), the substrates 211 and 213 are brought close together and eventually pressed against each other. During this process, when the value of the thickness T3 becomes zero, it can be detected that the substrates 211 and 213 are in contact without any gaps and have been bonded together. Displacement sensors 353 may be placed at the center, middle, and periphery of the substrates 211 and 213, respectively, as shown in detectors 341, 342, and 343, to detect the position of the boundary of the contact area at each location. In this case, the control unit 150 determines that the formation of the starting point 231 is complete when contact is detected at the center, and determines that bonding is complete when contact is detected at the periphery.

[0121] As shown in Figures 20, 21, and 22, the displacement meter 353, which acts as the detector 341 in the observation unit 344, has multiple measurement targets. Therefore, the detection accuracy of the detector 341 may be improved by selecting two or more of the multiple detection targets, for example, those shown in Figures 20, 21, and 22, and measuring them in parallel.

[0122] Furthermore, although the above example described the case using an optical displacement meter, several types of displacement meters are known, including eddy current type, ultrasonic type, and contact type. Of course, other types of displacement meters may also be used. In addition, different types of displacement meters may be mixed among the multiple detectors 341, 342, and 343 that form the observation section 344. Furthermore, the displacement of the upper surface of the substrate 213, i.e., the distance between the upper surface of the substrate 213 and the holding surface of the substrate holder 223, may be measured by the displacement meter 353 while the expansion of the contact area is progressing, based on the state in which the upper substrate 213 is held by the substrate holder 223. This distance value is one piece of information regarding the state of expansion of the contact area. In this case, the control unit 150 may determine that bonding is complete when the displacement of the upper surface of the substrate 213 becomes 0 and the amount of displacement becomes constant, or when the amount of change becomes smaller than a predetermined value.

[0123] Figure 23 is a schematic diagram of an observation section 345 having a different structure. In the bonded section 300 having the observation section 345, observation windows 327, 328, and 329 are provided on the upper stage 322, and observation holes 227, 228, and 229 are provided on the substrate holder 221 held on the upper stage, similar to the observation section 344 shown up to Figure 22.

[0124] Furthermore, in the bonding section 300 having the observation section 345, observation windows 327, 328, and 329 are also provided in the lower stage 332. In addition, observation holes 227, 228, and 229 are also provided in the flat substrate holder 223 held by the lower stage 332.

[0125] Furthermore, in the observation unit 345, the light source 351 irradiates the substrates 211 and 213 with light through the observation windows 327, 328, and 329 of the upper stage 322 and the observation holes 227, 228, and 229 of the upper substrate holder 221 in the figure, while the light receiving unit 352 receives the irradiated light through the observation windows 327, 328, and 329 of the lower stage 332 and the observation holes 227, 228, and 229 of the lower substrate holder 223 in the figure. With this structure, the light receiving unit 352 may observe the bonding state of the substrates 211 and 213 based on the amount of irradiated light that has passed through the substrates 211 and 213. The amount of irradiated light is one piece of information regarding the state of the expansion of the contact area. By experimentally determining in advance the amount of light when the formation of the starting point 231 is complete and the amount of light when the bonding is complete, the control unit 150 determines that the formation of the starting point 231 is complete and the bonding is complete based on the amount detected by the observation unit 345 being the value determined in advance. In the examples shown in Figures 4 to 23, the bonding wave propagation speed, i.e., the expansion speed of the contact area, may be predicted based on the time from when detector 341 detects that the starting point formation is complete until detector 342 detects the boundary of the contact area, or the time from when detector 342 detects the boundary until detector 343 detects the boundary, thereby predicting the time when bonding will be completed. Furthermore, while an example was shown in which three detectors 341, 342, and 343 are placed in the center, middle, and periphery of the substrates 211 and 213, instead of this, or in addition to this, multiple detectors may be arranged so that the periphery of the substrate that remains fixed to the stage without being released during bonding can be observed. In this case, bonding is determined to be complete when the periphery of the released substrate is detected by all of the multiple detectors. In addition, the progress of the bonding wave can be understood based on the detection timing of the periphery of the substrate by the multiple detectors. That is, if the detection timing of one detector differs from that of other detectors, it can be seen that the bonding wave is progressing slowly in the region containing the periphery where the detection timing is delayed. In this case, the control unit 150 provides feedback to the device to accelerate the progress of the bonding wave in the region where the progress is slow.

[0126] Figure 24 is a schematic diagram showing another structure of the detector 343 in the bonded portion 300. As already explained, the peripheral edges of the substrates 211 and 213 remain exposed to the outside even after the substrates 211 and 213 are bonded together. Therefore, the detector 343 that detects the bonding at the peripheral edges of the substrates 211 and 213 can have a different structure from the other detectors 341 and 342.

[0127] The illustrated detector 343 includes a light source 351, a light receiving unit 352, and an optical fiber 354. The light source 351 illuminates the peripheral edges of the substrates 211 and 213 through the observation window 329 and the observation hole 229. One end of the optical fiber 354 is positioned near the edge of the substrate 213 held by the lower stage 332. As a result, the optical fiber 354 receives illumination light scattered by the peripheral edge of the substrate 213.

[0128] The other end of the optical fiber 354 is positioned toward the light-receiving unit 352. As a result, the light incident on the optical fiber 354 is incident on the light-receiving unit 352. Upon receiving the light, the light-receiving unit 352 generates an electrical signal and inputs it to the control unit 150. The electrical signal input from the light-receiving unit 352 to the control unit 150 is one of the pieces of information regarding the state of the contact area expansion.

[0129] Figure 25 is a schematic diagram illustrating the operation of the detector 343 shown in Figure 24. When the substrates 211 and 213 are bonded together to their peripheral edges at the bonding portion 300, the illumination light from the light source 351 is instead directed onto the substrate 211 and scattered. As a result, the illumination light no longer enters the optical fiber 354 positioned to the side of the substrate 213. This changes the electrical signal input from the light receiving unit 352 to the control unit 150, allowing the control unit 150 to determine that the substrate 211 has been bonded to the substrate 213 up to its peripheral edge.

[0130] Figure 26 is a schematic diagram of an observation unit 346 having a different structure. The observation unit 346 has multiple light sources 361, 362, and 363, and light receiving units 371, 372, and 373, respectively.

[0131] The light-receiving units 371, 372, and 373 are arranged in the planar direction of the substrates 211 and 213, with the substrates 211 and 213 in between, facing the light sources 361, 362, and 363. One light-receiving unit 371 is positioned opposite one light source 361, with the center of the substrates 211 and 213 in between. Another light-receiving unit 373 is positioned opposite another light source 363, with the region including the periphery of the substrates 211 and 213 in between. Yet another light-receiving unit 372 is positioned opposite a light source 362 located between the light sources 361 and 362.

[0132] Figure 27 is a schematic diagram illustrating the operation of the observation unit 346 shown in Figure 26. Figure 27 shows the substrates 211 and 213 being observed by the observation unit 346, as viewed from the light-receiving units 371, 372, and 373 on the side in the planar direction.

[0133] In the illustrated diagram, the substrates 211 and 213 are already bonded together as shown in Figure 17, with the upper substrate 211 released from the upper stage 322 (step S109 in Figure 3). Therefore, when viewed from the light-receiving units 371 and 372, the width of the light beam of the light emitted by the light sources 361 and 362 onto the substrates is narrowed as it is blocked by the bonded substrates 211 and 213. Consequently, the light-receiving units 371 and 372 input an electrical signal to the control unit 150 when a small amount of light is received. The electrical signal input from the light-receiving units 371 and 372 to the control unit 150 is one piece of information regarding the state of the expansion of the contact area. By receiving light with the light-receiving unit 371 even before the two substrates 211 and 213 come into contact and detecting the change in the amount of light received, it may be determined that a starting point has been formed when this rate of change becomes 0 and the value of the light amount remains constant until a predetermined time has elapsed, or when the rate of change becomes smaller than a predetermined value. The light-receiving unit 372 may also detect changes in the amount of light received, and when the rate of change becomes 0 and the value of the light intensity remains constant until a predetermined time has elapsed, or when the rate of change becomes smaller than a predetermined value, it may be determined that the bonding wave that spread from the bonding starting point 231 has reached an intermediate point between the center and the periphery of the substrates 211 and 213.

[0134] In contrast, in the illustrated state, the edges of substrates 211 and 213 are not yet bonded together. Therefore, the light emitted by the light source 363 onto substrates 211 and 213 passes between the substrates 211 and 213 and is received by the light receiving unit 372 with a wide beam width. Consequently, the light receiving units 371 and 372 input electrical signals to the control unit 150 when strong illumination light is received.

[0135] In this way, the observation unit 346 can detect, based on the output of the light receiving unit 371, that a bonding starting point 231 is formed at the center of the substrates 211 and 213. The observation unit 346 can also detect, based on the output of the light receiving unit 372, that the bonding of the substrates 211 and 213 is expanding from the center toward the periphery. Furthermore, the observation unit 346 can determine, based on the output of the light receiving unit 373, that the rate of change becomes 0 and the light intensity value remains constant until a predetermined time has elapsed, or that the rate of change becomes smaller than a predetermined value, that the bonding of the substrates 211 and 213 has been completed to the periphery.

[0136] Furthermore, the surfaces of substrates 211 and 213 are not necessarily flat due to the circuit region 216, etc. Also, substrates 211 and 213 themselves may undergo deformation such as warping during the process of forming the circuit region 216. In addition, in the bonding portion 300, the substrates 211 and 213 to be bonded may be deformed to correct the magnification, distortion, etc. of substrates 211 and 213. For this reason, a gap may not be formed between substrates 211 and 213 that allows light to travel in a straight line from the light sources 361, 362, and 363 to the light receiving portions 371, 372, and 373.

[0137] However, if the gap between substrates 211 and 213 is continuous from the light sources 361, 362, and 363 to the light receiving units 371, 372, and 373, then some of the irradiated light will reach the light receiving units 371, 372, and 373. Therefore, even if the gap between substrates 211 and 213 is such that the light receiving units 371, 372, and 373 cannot see through to the light sources 361, 362, and 363, the observation unit 346 can detect whether or not the substrates 211 and 213 are bonded together.

[0138] Alternatively, the illumination light generated by the light sources 351, 361, 362, and 363 in the observation units 344, 345, and 346 may be modulated at a predetermined frequency, and the illumination light may be detected by lock-in detection in the light receiving units 352, 371, 372, and 373. This eliminates the influence of background light and allows for accurate detection of weak illumination light.

[0139] Figure 28 is a schematic diagram of an observation unit 347 having a different structure. The observation unit 347 includes a light source 361, an imaging unit 374, and a background plate 364.

[0140] The light source 361 and the imaging unit 374 are positioned on the side of the substrates 211 and 213 in the planar direction, on the same side as the substrates 211 and 213. The illumination light generated by the light source 361 is shone toward the substrates 211 and 213 from the same side as the imaging unit 374, illuminating the imaging field of view of the imaging unit 374.

[0141] The background plate 364 is positioned on the side opposite to the substrates 211 and 213 relative to the light source 361 and the imaging unit 374. As a result, when the imaging unit 374 images the substrates 211 and 213, the background plate 364 forms the background for the substrates 211 and 213. The background plate 364 has a color and brightness that provides strong contrast to the images of the substrates 211 and 213 captured by the imaging unit 374.

[0142] In the observation unit 347, the imaging field of the imaging unit 374 extends from the center to the periphery of the substrates 211 and 213, as shown by the dotted line in the figure. As a result, in the observation unit 347, the imaging unit 374 collectively performs the roles of the light receiving units 371, 372, and 373 of the observation unit 346 shown in Figures 26 and 27. The image captured by the imaging unit 374 is acquired by the control unit 150 and subjected to image processing.

[0143] In the bonding section 300, when the upper stage 322 and lower stage 332, each holding the substrates 211 and 213, face each other, the imaging unit 374 captures an image of the background plate 364 visible between the substrates 211 and 213. When the substrates 211 and 213 form the bonding starting point 231 in step S108 (see Figure 3), a portion of the image of the background plate 364 is obscured and divided by the substrates 211 and 213 in the image captured by the imaging unit 374. As a result, the control unit 150 can detect that the bonding starting point 231 has been formed.

[0144] Next, in step S110, the imaging unit 374 can continuously monitor the expansion of the contact area between substrates 211 and 213. Furthermore, in step S112, the imaging unit 374 can detect that the contact area between substrates 211 and 213 has reached the periphery of the substrate and that bonding is complete. In this way, the observation unit 347 can directly image the bonding of substrates 211 and 213 and continuously detect the bonding based on the distance between substrates 211 and 213 in the captured image.

[0145] In the above example, the imaging unit 374 was positioned laterally to the substrates 211 and 213 in the planar direction to detect bonding. However, for example, the imaging unit 374 may be positioned laterally to the substrates 211 and 213 in the thickness direction, using an imaging unit 374 that is sensitive to wavelengths that pass through at least one of the upper stage 322 and the lower stage 332 and the substrate holders 221 and 223 held by the stage, to detect bonding.

[0146] Furthermore, the images acquired by the imaging unit 374 are not limited to images that directly capture the shapes of the substrates 211 and 213. For example, the bonding state of the substrates 211 and 213 may be detected based on changes in interference fringes caused by optical phenomena such as interference occurring between the substrates 211 and 213.

[0147] Figure 29 is a schematic diagram of a bonding section 300 equipped with an observation section 348 having a different structure. The bonded section 300 shown in the figure has the same structure as the bonded section 300 shown in Figure 6, etc., except for the parts described below. Therefore, the same reference numerals are used for common components to avoid redundant explanations.

[0148] The bonded section 300 shown in the figure has a different structure from the bonded section 300 shown in Figure 6, in that it has an observation section 348 with a load cell 380 instead of an observation section 344 for optically observing the bonded state. The load cell 380 is positioned between the top plate 316 of the frame 310 and the upper stage 322.

[0149] As a result, the observation unit 348 can continuously detect the reaction force that the upper stage 322 receives from the substrates 211 and 213 when the lower stage 332 is raised by the lifting drive unit 338, using the load cell 380. That is, the load cell 380 first detects an increase in reaction force when the substrates 211 and 213, which were pressed together in step S107 (see Figure 3), come into contact with each other and form a bonding starting point 231. The reaction force detected by the load cell 380 is one piece of information regarding the state of expansion of the contact area and is transmitted to the control unit 150. When the reaction force reaches a predetermined value, or when a predetermined value is maintained for a threshold time or longer, the control unit 150 can determine that a bonding starting point 231 has been formed on the substrates 211 and 213 (step S108: YES). Furthermore, when forming the starting point 231, a portion of substrate 213 is pressed against a portion of substrate 211 via an atmosphere or the like sandwiched between substrates 211 and 213. After the atmosphere or the like is pushed out, substrates 211 and 213 come into direct contact with each other. As a result, the reaction force detected by the load cell 380 temporarily decreases when the atmosphere is pushed out. The control unit 150 may detect that the value of the load cell 380 has temporarily decreased, or that after temporarily decreasing, the value of the load cell 380 has increased again and exceeded a predetermined value, and determine that the starting point 231 for bonding has been formed on substrates 211 and 213.

[0150] Subsequently, once the entire substrates 211 and 213 are bonded together, the force with which the lifting drive unit 338 raises the lower stage 332 is directly applied to the load cell 380. Therefore, the control unit 150 can determine that the entire substrates 211 and 213 have been bonded together by the increase in the reaction force detected by the load cell 380 of the observation unit 348.

[0151] Thus, the bonding state of the substrates 211 and 213 can also be detected by changes in mechanical properties. The structure of the observation unit 348 that detects based on mechanical properties is not limited to the above. The reaction force of the substrates 211 and 213 may be detected based on changes in drive power corresponding to changes in the drive load on the lifting drive unit 338, changes in the pressure of the working fluid, etc. When determining the completion of bonding by detecting the drive load of the lifting drive unit 338, as in the illustrated example, when the upper substrate 211 is laminated onto the lower substrate 213, the load of the substrate 211 is added to the lower stage 332 as the contact area of ​​the substrates 211 and 213 expands, so the thrust of the lifting drive unit 338 increases. The control unit 150 determines that bonding is complete when it detects that this change in thrust has stopped and the load value has become constant, that the constant load value has been maintained for a threshold time, or that the rate of change of thrust has become smaller than a predetermined value.

[0152] Furthermore, the observation section 348 can also be formed by using a mechanical displacement sensor that has a contactor that makes contact when the peripheral edge of the substrate 211, which has been released from being held by the upper stage 322 in step S109, is displaced to a position where it is in contact with the fixed substrate 213.

[0153] Figure 30 is a schematic diagram of a bonding section 300 equipped with an observation section 349 having a different structure. The bonded section 300 shown in the figure has the same structure as the bonded section 300 shown in Figure 6, etc., except for the parts described below. Therefore, the same reference numerals are used for common components to avoid redundant explanations.

[0154] The bonded section 300 shown in the figure has a different structure from the bonded section 300 shown in Figure 6, in that it has an observation section 349 with a microphone 390 instead of an observation section 344 that optically detects the bonded state. The microphone 390 is suspended from the top plate 316 of the frame 310 and detects elastic waves generated between the upper stage 322 and the lower stage 332.

[0155] In the bonding section 300, the substrates 211 and 213 generate elastic waves during the bonding process. For example, until released in step S109 (see Figure 3), the substrate 211 held on the upper stage 322 is in a curved state due to being held by the substrate holder 221 having a curved holding surface 222. On the other hand, once released from step S109, the substrate 211 deforms to conform to the shape of the other substrate 213 as the bonding progresses.

[0156] As a result of this deformation, the substrate 211 generates minute elastic waves. Therefore, by acquiring an electrical signal based on the sound detected by the microphone 390, the control unit 150 can determine that bonding is progressing on the substrates 211 and 213.

[0157] Furthermore, during the bonding process of substrates 211 and 213, the atmosphere initially sandwiched between substrates 211 and 213 is pushed out from between them. The vibrations generated in the atmosphere due to this movement can also be detected as acoustic elastic waves. Therefore, the microphone 390 can detect the elastic waves generated in the atmosphere to detect the continuation and completion of the bonding process.

[0158] Furthermore, when the bonding of substrates 211 and 213 reaches the periphery of substrates 211 and 213, the periphery of one substrate 211 comes into contact with the other substrate 213, causing the continuous displacement of substrate 211 to stop rapidly. This generates a collision sound between substrates 211 and 213. Therefore, by acquiring the electrical signal generated by the microphone 390 that detects this collision sound, the control unit 150 can determine that the bonding of substrates 211 and 213 has reached the periphery and is complete.

[0159] Furthermore, the elastic waves generated by the substrate 211 do not necessarily have frequencies within the audible range. Therefore, it is preferable that the microphone 390 used in the observation unit 349 has sensitivity outside the audible range as well.

[0160] Figure 31 is a schematic diagram of a bonded section 300 equipped with an observation section 610 having a different structure. The bonded section 300 shown in the figure has the same structure as the bonded section 300 shown in Figure 30, except for the parts described below. Therefore, the same reference numerals are used for common components to avoid redundant explanations.

[0161] In the illustrated bonding section 300, the observation section 610 has a vibration generating section 391 and a vibration detection section 392 instead of a microphone 390. The vibration generating section 391 is located on the upper stage 322 and generates vibrations at a predetermined frequency. When the vibration generating section 391 generates vibrations, the generated vibrations are transmitted to the substrate 211 via the upper stage 322 and the substrate holder 221. The vibration generating section 391 can be formed from a piezoelectric element or the like.

[0162] The vibration detection unit 392 is located on the lower stage 332 and detects vibrations transmitted from the substrate 211 to the lower stage 332 via the substrate 213 and the substrate holder 221. Therefore, until the substrates 211 and 213 are pressed against each other in step S107 (see Figure 3), the vibration detection unit 392 does not detect vibrations even if the vibration generating unit 391 generates vibrations. However, once the substrates 211 and 213 come into contact with each other in step S107, the vibration detection unit 392 can detect the vibrations generated by the vibration generating unit 391.

[0163] Furthermore, even after the substrates 211 and 213 come into contact in step S107, the acoustic impedance of the vibration system formed by the upper stage 322, substrate holders 221 and 223, substrates 211 and 213, and lower stage 332 changes in accordance with the change in the contact state of the substrates 211 and 213. Therefore, the detection result by the vibration detection unit 392 also changes when the vibration generating unit 391 generates vibration. This allows the vibration detection unit 392 to detect the progress and completion of bonding on the substrates 211 and 213.

[0164] Figure 32 is a schematic diagram of a bonded section 300 equipped with an observation section 620 having a different structure. The bonded section 300 shown in the figure has the same structure as the bonded section 300 shown in Figure 6, etc., except for the parts described below. Therefore, the same reference numerals are used for common components to avoid redundant explanations.

[0165] In the bonded portion 300 shown in the figure, the observation portion 620 has a capacitance detection portion 621. The capacitance detection portion 621 applies a periodically changing electrical signal to an LC resonant circuit formed by the capacitance between the substrates 211 and 213 to be measured and a standard inductor. At this time, the capacitance detection portion 621 superimposes an AC voltage on the DC voltage applied to the electrodes of two substrate holders 221 and 223 which have the function of an electrostatic chuck, and detects the AC component of the electrical signal that changes in accordance with the change in capacitance in the substrates 211 and 213. The capacitance value and the rate of change value detected by the capacitance detection portion 621 are one piece of information regarding the state of contact area expansion.

[0166] The total capacitance between the two substrate holders 221 and 232 is the sum of the capacitance between the electrode of substrate holder 221 and substrate 211, the capacitance between the silicon layer and the surface oxide layer of substrate 211, the capacitance between the two substrates 211 and 213, the capacitance between the silicon layer and the oxide layer of substrate 213, and the capacitance between the electrode of substrate holder 223 and substrate 213. The capacitance between substrates 211 and 213 increases as the distance between them decreases, reaching its maximum when parts of substrates 211 and 213 come into contact, and the overall capacitance also reaches its maximum. In other words, it reaches its maximum value when a starting point is formed between substrates 211 and 213. Subsequently, as the bonding wave progresses, the distance between substrate 211 and the electrodes of substrate holder 221 increases, causing the overall capacitance to decrease.

[0167] In this way, the capacitance changes in accordance with the change in the bonding state of substrates 211 and 213. By detecting this change, the bonding state of substrates 211 and 213 can be electrically detected.

[0168] The control unit 150 detects when the capacitance value exceeds a threshold or reaches a predetermined maximum value and determines that a starting point has been formed between the substrates 211 and 213. Alternatively, the control unit 150 may determine that a starting point has been formed when it detects that a predetermined time has elapsed after the capacitance value exceeds a threshold or reaches a predetermined maximum value. The predetermined time is determined according to the bonding strength between the parts of contact between the substrates 211 and 213, and is set, for example, based on the activation conditions of the substrates 211 and 213. Alternatively, the control unit 150 may determine that a starting point has been formed when it detects that the size of the contact area of ​​the parts of contact between the substrates 211 and 213 has reached a predetermined size. The predetermined area size is determined according to the bonding strength between the parts of contact between the substrates 211 and 213, and may be determined experimentally in advance. The area size can be detected by measuring the change in capacitance when the contact area expands slightly after the substrates 211 and 213 make single-point contact, or by taking external images using means such as those shown in Figure 28.

[0169] Furthermore, the control unit 150 determines that bonding is complete when it detects that the capacitance value has become constant, that a constant load value has been maintained for a threshold time, or that the rate of change of capacitance has become smaller than a predetermined value. Alternatively, the control unit 150 may determine that bonding is complete when it detects that the total capacitance value has returned to the value before the substrates 211 and 213 came into contact.

[0170] As described above, in the bonded portion 300, changes in the bonded state can be detected by changes in various properties such as optical properties, mechanical properties, and electrical properties of the substrates 211 and 213. Furthermore, the bonded portion 300 may be formed by combining multiple of the various observation units 344, 345, 346, 347, 348, 349, 610, and 620 described above.

[0171] Figure 33 is a partially enlarged view showing a schematic cross-section of a modified example of the bonded portion 300. The bonded portion 300 shown has the same structure as the bonded portion 300 shown in Figure 10, except for the parts described below. Therefore, the same reference numerals are used for common elements to avoid redundant explanations.

[0172] In the illustrated bonded portion 300, the upper stage 322 has a plurality of ventilation holes 325 that penetrate in the thickness direction. The lower end of each ventilation hole 325 in the figure opens to the lower surface of the upper stage 322. The upper end of each ventilation hole 325 in the figure is connected to a tank 631 located outside the bonded portion 300 via a valve 632.

[0173] Tank 631 contains a fluid, such as dry air or an inert gas, that can be safely mixed into the atmosphere of the substrates 211 and 213, at a pressure higher than atmospheric pressure. Valve 632 opens and closes under the control of the control unit 150. When valve 632 is open, the fluid supplied from tank 631 is injected from the upper stage 322 through the vent hole 325.

[0174] Furthermore, in the bonded section 300 shown in the figure, the substrate holder 221 held by the upper stage 322 also has a plurality of ventilation holes 225 that penetrate in the thickness direction at positions corresponding to the ventilation holes 325 of the upper stage 322. As a result, when the valve 632 is opened under the control of the control unit 150, a fluid supplied from the tank 631, such as an inert gas like nitrogen or argon, is injected from the ventilation holes 225 of the substrate holder 221. This allows the substrate 211 to be forcibly pushed away if, for example, the substrate 211 remains attached to the substrate holder 221 even after the power supply to the electrostatic chuck is cut off, thereby improving the throughput of the substrate bonding apparatus 100.

[0175] Figure 34 is a flowchart showing part of the control procedure around the stage in the bonding section 300 described above. The illustrated procedure may also be performed during the process from step S107 to step S112 in the procedure shown in Figure 3. Therefore, in the following explanation, the procedure shown in Figure 34 will be shown along with its correspondence to the procedure shown in Figure 3.

[0176] First, in step S106 of Figure 3, when the substrate 211 held on the upper stage 322 and the substrate 213 held on the lower stage 332 are aligned, the control unit 150 raises the lower stage 332 (step S201) and determines whether the substrates 211 and 213 have come into contact (step S202). The raising of the lower stage 332 continues until the substrates 211 and 213 come into contact (step S202: NO).

[0177] When the control unit 150 detects that the substrates 211 and 213, which have come into contact as the lower stage 332 rises (step S202: YES), the control unit 150, Lower Stage 332 The substrate 213 held on the upper stage 322 and the substrate 211 held on the upper stage 322 move closer to each other. As the lower stage 332 rises further, the substrates 211 and 213 come into contact with each other, as shown in Figure 35 (Step S202: YES).

[0178] Figure 35 is a schematic cross-sectional view showing the state in which the substrates 211 and 213 come into contact as the lower stage 332 rises. Elements common to Figure 34 are given the same reference numerals, and redundant explanations are omitted. As shown in the figure, the substrate 211 held on the upper stage 322 is held with its central portion protruding downward in the figure, so the central portion is first partially pressed against the substrate 213 held on the lower stage 332 in a flat state (step S107).

[0179] Referring again to Figure 34, the control unit 150 then starts measuring the pressure exerted on the upper stage 322 by the rising of the lower stage 332 through a load cell 380 positioned between the upper stage 322 and the top plate 316 (step S203). The control unit 150 also determines whether or not a region of adhesion has been formed on the contacting substrates 211 and 213 (step S108), and waits for the starting point of adhesion to be formed on the substrates 211 and 213 (step S204:NO).

[0180] As a result, when it is detected that the starting point for bonding has been formed on the substrates 211 and 213 (step S204: YES), the control unit 150 sets the vertical position of the lower stage 332 at this point, i.e., the Z-direction position L0 shown in Figure 35, as the reference position for controlling the position of the lower stage 332. The control unit 150 also stores the pressure measured by the load cell 380 when the lower stage 332 is in the reference position as the control reference pressure for controlling the Z-direction position of the lower stage (step S205).

[0181] Furthermore, when it is detected that a bonding starting point has been formed on the substrates 211 and 213 (step S204: YES), the control unit 150 releases the holding of the substrate 211 at least on the upper stage 322 side (steps S109, S206). The control unit 150 also opens the valve 632 and blows fluid through the vents 325 and 225, thereby pushing the substrate 211 away from the substrate holder 221 held on the upper stage 322, as shown in Figure 36 (step S07).

[0182] Figure 36 is a schematic cross-sectional view showing the state in which the control unit 150 pushes the substrate 211 away from the upper stage 322 by injecting fluid after the bonding starting point has been formed between the substrates 211 and 213. When fluid is injected from the upper stage 322 side and blown onto the substrate 211, the fluid pressure also acts on the lower stage 332 through the lower substrate 213 and substrate holder 223 that are in contact with the substrate 211. As a result, the load on the lifting drive unit 338 that drives the lower stage 332 increases, and the lower stage 332 is displaced below the reference position L0.

[0183] Here, the substrate 211, which was initially held on the upper stage 322, is now held on the lower stage 332 213 It is partially bonded to the upper stage 322. Therefore, when the lower stage 332 descends, the upper substrate 211 also descends with it. As a result, the gap between the upper substrate holder 221 held by the upper stage 322 and the substrate 211 widens, and the fluid pressure between the substrate holder 221 and the substrate 211 decreases.

[0184] As a result, the pressure measurement from the load cell 380 decreases (step S208: YES), so the control unit 150 operates the lifting drive unit 338 to raise the lower stage 332 in order to bring the measured value of the load cell 380 closer to the control reference pressure (step S209). In other words, the Z position of the lower stage 332 is controlled to be a position where the force acting on the substrate 211 from the fluid and the force lifting the lower stage 332 by the lifting drive unit 338 are in equilibrium. When the substrate 211 moves away from the upper substrate holder 221 due to the injection of fluid, the space between the substrate 211 and the substrate 213 increases, so the fluid pressure between the substrates 211 and 213 decreases, and the force balance is disrupted. For this reason, in order to increase the fluid pressure, the lower stage 332 is raised to a position where the fluid pressure and the force of the lifting drive unit 338 are in equilibrium. In this way, as shown in Figure 37, the lower stage 332 rises and approaches the reference position L0 again.

[0185] After this, the control unit 150 detects the pressure value measured by the load cell 380 and continues to control the position of the lower stage 332 so that the upward force of the lower stage 332 by the lifting drive unit 338 and the pressure of the fluid injected from the upper stage 322 are in equilibrium and the value of the load cell 380 becomes constant (step S208: YES). However, while the bonding of the substrates 211 and 213 is progressing, the state between the upper substrate holder 221 and the upper substrate 211 changes over time, so the position of the lower stage 332 in the Z direction is not stable. As the bonding wave progresses and the contact area expands, causing the substrate 211 to move away from the upper substrate holder 221, the space between the substrate 211 and the substrate holder 221 gradually increases, and the fluid pressure gradually decreases. Therefore, during the process of expanding the contact area, the Z position of the lower stage 332 gradually rises. Once bonding is complete, the size of the space between the substrate 211 and the substrate holder 221 remains unchanged, and the fluid pressure also remains unchanged, so the Z position of the lower stage 332 becomes constant.

[0186] Figure 38 is a schematic cross-sectional view showing the state after the bonding of substrates 211 and 213 in the bonding section 300 has been completed through the process described above. As shown in the figure, once the bonding of substrates 211 and 213 is complete and the state between the upper substrate holder 221 and substrate 211 no longer changes, the change in the pressure value measured by the load cell 380 converges, and the position of the lower stage 332 also stops changing. Therefore, by setting a threshold time determined in advance, for example through experimentation, the control unit 150 can determine that the bonding of substrates 211 and 213 is complete when the pressure measurement value from the load cell 380 or the detected value from the position detection unit that detects the Z position of the lower stage 332 does not change beyond the threshold time (step S210).

[0187] In the above-described embodiment, the control unit 150 can determine that an abnormality has occurred in bonding if the bonding wave stops progressing or if the degree of progress is uneven in the circumferential direction of the substrates 211 and 213. In this case, the control unit 150 outputs a signal to resolve the abnormality according to the cause of the abnormality.

[0188] For example, if the bonding wave propagation is uneven due to the presence of debris between substrates 211 and 213, a signal is sent to the cleaning device to clean the substrate holder or stage.

[0189] When the aforementioned actuator deforms the substrate, if the cause of the abnormality is the amount of deformation of the substrate by the actuator, the control unit 150 outputs a control signal to the control unit that controls the drive of the actuator to adjust the amount of drive of the actuator in order to adjust the amount of deformation.

[0190] In the examples shown in Figures 33 to 38, if the cause of the abnormality is the fluid flow rate or fluid pressure, the control unit 150 adjusts the flow rate and fluid pressure from the vent holes 325 corresponding to the region where the bonding wave is progressing slower or faster than other regions.

[0191] If the cause of the abnormality is at least one of the ambient temperature and pressure around the upper stage 322 and the lower stage 332, a control signal is output to a temperature control device or pressure regulator (not shown) to change the temperature and pressure.

[0192] If a region of the substrate 211 in which the bonding wave is progressing slowly is detected, at least one of the upper stage 322 and the lower stage 332 may be tilted so that the region moves closer to the substrate 213.

[0193] If the cause of the abnormality is non-uniform activation within the plane of at least one of the two substrates 211, 213, the control unit 150 outputs a control signal to the activation device to adjust the degree of activation according to the distribution of the bonding wave progression. If the cause of the abnormality is deformation, including warping, of the substrates 211 and 213, the control unit 150 outputs a control signal to the pretreatment equipment, such as the film deposition apparatus and exposure apparatus used in the manufacturing process of the substrates 211 and 213, instructing them to adjust the amount of deformation occurring in the substrates. Furthermore, if the time required to form the starting point is long, it is thought that this may be due to a weak activation level of the substrate or a weak pressing force when substrates 211 and 213 are in contact. Therefore, the control unit 150 outputs a control signal to the activation device to adjust the activation level and controls the amount of drive of the lower stage 332 when substrates 211 and 213 are in contact.

[0194] The feedback control by the control unit 150 described above may be performed in real time, or it may be performed when bonding the next substrate. Alternatively, the feedback control may be performed for each batch of substrates, each time the bonding process recipe is changed, etc.

[0195] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0196] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]

[0197] 100 Substrate bonding device, 110 Housing, 120, 130 Substrate cassette, 140 Transport unit, 150 Control unit, 210, 211, 213 Substrate, 212 Scribe line, 214 Notch, 216 Circuit area, 218 Alignment mark, 220, 221, 223 Substrate holder, 222, 224 Holding surface, 225, 325 Ventilation holes, 227, 228, 229 Observation holes, 230 Bonded substrate, 231 Bonding starting point, 232 Bonding wave, 300 Bonding unit, 310 Frame, 312 Bottom plate, 314 Support column, 316 Top plate, 322 Upper stage, 324, 334 Microscope, 326, 336 Activation device, 327, 328, 329 Observation window, 331 X-direction drive unit, 332 Lower stage, 333 Y-direction drive unit, 338 Lifting drive unit, 341, 342, 343 Detector, 344, 345, 346, 347, 348, 349, 610, 620 Observation unit, 351, 361, 362, 363 Light source, 354 Optical fiber, 364 Background plate, 352, 371, 372, 373 Light receiving unit, 353 Displacement meter, 374 Imaging unit, 380 Load cell, 390 Microphone, 391 Vibration generation unit, 392 Vibration detection unit, 400 Holder stocker, 500 Pre-aligner, 621 Capacitance detection unit, 631 Tank, 632 Valve

Claims

1. A bonding section for bonding the first substrate and the second substrate, The system includes an acquisition unit that acquires information regarding the degree of progression of a bonding wave, which is the outer edge of a contact area where the first substrate and the second substrate are in contact, moving from the inside outward of the first substrate or the second substrate, and which differs from other areas. The bonding portion bonds the third substrate and the fourth substrate in such a way that the unevenness of the bonding process is suppressed, and includes a first holding portion for holding the first substrate, and a second holding portion located above the first holding portion for holding the second substrate. The second retaining portion includes a ventilation hole, The bonding portion supplies gas through the ventilation holes to separate the second substrate from the holding surface of the second holding portion by moving the different regions from a state where they are held along the holding surface of the second holding portion to a state where they are separated from the holding surface of the second holding portion, and adjusts the flow rate or fluid pressure of the gas supplied to the second substrate through the ventilation holes corresponding to the different regions so as to suppress unevenness in the degree of progress. A circuit board bonding machine.

2. The bonding portion includes a lifting drive unit for raising and lowering the first holding portion, The present invention further includes a load cell that detects the force when the first substrate is pressed against the second substrate by raising the first holding portion, The bonding portion detects the downward displacement of the first holding portion due to the pressure of the gas supplied through the ventilation holes during the bonding process of the first substrate and the second substrate, and controls the position of the first holding portion so that the force acting on the second substrate from the gas and the force lifting the first holding portion by the lifting drive unit are in equilibrium. The substrate bonding apparatus according to claim 1.

3. At least one of the first holding portion that holds the third substrate and the second holding portion that holds the fourth substrate includes an actuator. The bonding portion deforms at least one of the third substrate and the fourth substrate by controlling the actuator so as to suppress the unevenness of the degree of deformation. The substrate bonding apparatus according to claim 1.

4. The bonding portion controls the amount of upward movement of the first holding portion when the third substrate and the fourth substrate come into contact, so as to suppress the unevenness of the progress. The substrate bonding apparatus according to claim 1.

5. The device includes a temperature control device that adjusts the temperature of at least one of the third substrate and the fourth substrate so as to suppress the unevenness of the progression, The substrate bonding apparatus according to claim 1.

6. The activation device includes an activation device for activating at least one of the third substrate and the fourth substrate so as to suppress the non-uniformity of the progression, The substrate bonding apparatus according to claim 1.

7. To suppress the unevenness of the progression, the cleaning device includes a first holding part that holds the third substrate and a second holding part that holds the fourth substrate, The substrate bonding apparatus according to claim 1.

8. The third and fourth substrates are substrates whose deformation amount has been adjusted by a processing device so as to suppress the non-uniformity of the progression. The substrate bonding apparatus according to claim 1.

9. The aforementioned processing apparatus is a film deposition apparatus. The substrate bonding apparatus according to claim 8.

10. The acquisition unit includes a detector for detecting reflected light from the first substrate or the second substrate, an observation unit for capturing an image of the contact area, a displacement meter for measuring a quantity relating to the distance between the first substrate and the second substrate, a light receiving unit for detecting light transmitted through the first substrate and the second substrate, a light receiving unit for detecting light scattered by the peripheral edge of the first substrate or the second substrate, a light receiving unit for detecting light passing between the first substrate and the second substrate, an imaging unit for imaging the first substrate and the second substrate from the side of the first substrate and the second substrate, a detection unit for detecting the force received by the stage holding the second substrate when the first substrate is pressed against the second substrate, an observation unit for detecting elastic waves or vibrations generated when the first substrate and the second substrate are bonded together, a detection unit for detecting the capacitance between the first substrate and the second substrate, or a detection unit for detecting the position of the stage in the predetermined direction when the first substrate and the second substrate are bonded together by moving the stage holding the first substrate in the predetermined direction. A substrate bonding apparatus according to any one of claims 1 to 9.

11. To obtain information regarding the degree of propagation of a bonding wave, which is the outer edge of the contact area where the first substrate and the second substrate are in contact, progressing from the inside outward of the first substrate or the second substrate, and which differs from other areas, This includes bonding the third substrate and the fourth substrate together in such a way that the unevenness of the progression is suppressed. The first substrate is held in the first holding part, The second substrate is held by the second retaining portion located above the first retaining portion. The bonding process includes supplying gas through ventilation holes corresponding to the different regions to separate the second substrate from the second holding portion, thereby moving the different regions from a state where they are held along the holding surface of the second holding portion to a state where they are separated from the holding surface of the second holding portion, and adjusting the flow rate or fluid pressure of the gas supplied to the ventilation holes corresponding to the different regions so as to suppress any unevenness in the degree of bonding. Method for bonding circuit boards.

12. In the other region, the bonding wave propagates in a first direction from the inside to the outside. In the aforementioned different regions, the bonding wave propagates in a second direction different from the first direction, from the inside to the outside. The information includes information relating to the time taken from the start to the completion of bonding the first substrate and the second substrate in the other region and the different region, The substrate bonding apparatus according to claim 1.

13. In the other region, the bonding wave propagates in a first direction from the inside to the outside. In the aforementioned different regions, the bonding wave propagates in a second direction different from the first direction, from the inside to the outside. The information includes information relating to the time taken from the start to the completion of bonding the first substrate and the second substrate in the other region and the different region, The substrate bonding method according to claim 11.

14. The third substrate is the first substrate, The fourth substrate is the second substrate. A substrate bonding apparatus according to any one of claims 1 to 9 and 12.

15. The third substrate is the first substrate, The fourth substrate is the second substrate. The substrate bonding method according to claim 11 or 13.

16. The third substrate is a different substrate from the first substrate. The fourth substrate is a different substrate from the second substrate. A substrate bonding apparatus according to any one of claims 1 to 9 and 12.

17. The third substrate is a different substrate from the first substrate. The fourth substrate is a different substrate from the second substrate. The substrate bonding method according to claim 11 or 13.

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