Substrate stacking apparatus and substrate stacking method

Abstract

The present invention provides a substrate bonding apparatus and a substrate bonding method that suppress relative positional misalignment of circuits on substrates after the substrates have been stacked. [Solution] In a substrate stacking apparatus, the aligner 300, which expands the contact area of ​​a first substrate 211 and a second substrate 213 that are partially in contact to stack the first substrate and the second substrate on top of each other, includes a suppression unit that suppresses misalignment between the first substrate and the second substrate due to differences in deformation amounts, where the amount of deformation occurring in at least multiple directions of the first substrate differs when the contact area expands. In the substrate stacking apparatus, the suppression unit may suppress misalignment so that the amount of misalignment is less than or equal to a predetermined value.

Description

Technical Field

[0006]

[0001] The present invention relates to a substrate stacking device and a substrate stacking method.

Background Art

[0002] There is a technique for manufacturing a stacked semiconductor device by stacking substrates (see, for example, Patent Document 1). Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-098186

Summary of the Invention

Problems to be Solved by the Invention

[0003] Even if the substrates are aligned before being stacked, when observed after the substrates are stacked, the circuits on the substrates may be misaligned with each other.

Means for Solving the Problems

[0004] In a first aspect of the present invention, there is provided a substrate stacking device that expands a contact area of a first substrate and a second substrate that are partially in contact from a part and stacks the first substrate and the second substrate on each other, and includes a suppression unit that suppresses a displacement between the first substrate and the second substrate due to a difference in deformation amounts that occur in at least a plurality of directions of the first substrate when the contact area expands.

[0005] In a second aspect of the present invention, there is provided a substrate processing method that expands a contact area of a first substrate and a second substrate that are partially in contact from a part and stacks the first substrate and the second substrate on each other, and includes a suppression step that suppresses a displacement between the first substrate and the second substrate due to a difference in deformation amounts that occur in at least a plurality of directions of the first substrate when the contact area expands.

[0006] The above summary of the invention does not list all the features of the present invention. Sub-combinations of these feature groups can also be inventions.

Brief Description of the Drawings

[0007] [Figure 1] This is a schematic diagram of the substrate stacking 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 the Alaina 300. [Figure 5] This is a schematic cross-sectional view of the Alaina 300. [Figure 6] This is a schematic cross-sectional view of the Alaina 300. [Figure 7] This is a schematic cross-sectional view of the Alaina 300. [Figure 8] This is a schematic cross-sectional view of the Alaina 300. [Figure 9] This is a schematic cross-sectional view showing the process of superimposing substrates 211 and 213. [Figure 10] This is a schematic diagram of substrates 211 and 213 in the superposition process. [Figure 11] This is a schematic diagram of substrates 211 and 213 in the superposition process. [Figure 12] This is a schematic diagram of substrates 211 and 213 in the superposition process. [Figure 13] This figure shows the misalignment in the laminated substrate 230. [Figure 14] This is a schematic diagram showing the correction method on substrate 210. [Figure 15] This is a schematic diagram showing the correction method on substrate 210. [Figure 16] This is a schematic diagram illustrating the correction method for silicon single crystal substrate 208. [Figure 17] This is a schematic diagram illustrating the correction method for silicon single crystal substrate 209. [Figure 18] This is a schematic cross-sectional view of the correction unit 601. [Figure 19] This is a schematic plan view of the correction unit 601. [Figure 20] This is a schematic diagram illustrating the operation of the correction unit 601. [Figure 21] It is a schematic diagram for explaining the correction of the substrate 211 by the correction unit 601. [Figure 22] It is a schematic diagram for explaining the correction using the correction unit 601. [Figure 23] It is a schematic diagram for explaining the operation of the correction unit 601. [Figure 24] It is a schematic cross-sectional view of the correction unit 602. [Figure 25] It is a schematic plan view of the correction unit 602. [Figure 26] It is a schematic diagram for explaining the operation of the correction unit 602. [Figure 27] It is a schematic cross-sectional view of the correction unit 603. [Figure 28] It is a schematic diagram for explaining the operation of the correction unit 603.

Mode for Carrying Out the Invention

[0008] Hereinafter, the present invention will be described through embodiments of the invention. The following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential for the solution of the invention.

[0009] FIG. 1 is a schematic plan view of a substrate stacking apparatus 100. The substrate stacking apparatus 100 includes a housing 110, substrate cassettes 120, 130 and a control unit 150 arranged outside the housing 110, and a transfer robot 140, an aligner 300, a holder stocker 400, and a pre-aligner 500 arranged inside the housing 110. The inside of the housing 110 is temperature-controlled, for example, maintained at room temperature.

[0010] One substrate cassette 120 accommodates substrates 210 to be stacked. The other substrate cassette 130 accommodates a laminated structure substrate 230 produced by stacking substrates 210. The substrate cassettes 120, 130 can be individually attached to and detached from the housing 110.

[0011] By using the substrate cassette 120, multiple substrates 210 can be loaded into the substrate stacking device 100 at once. Furthermore, by using the substrate cassette 130, multiple laminated substrates 230 can be unloaded from the substrate stacking device 100 at once.

[0012] The transport robot 140 is responsible for transporting items inside the housing 110. The transport robot 140 transports individual substrates 210, substrate holders 220, substrate holders 220 holding substrates 210, and laminated substrates 230 formed by stacking substrates 210.

[0013] The control unit 150 comprehensively controls and coordinates each part of the substrate stacking device 100. The control unit 150 also receives user instructions from an external source and sets the manufacturing conditions for producing the laminated substrate 230. Furthermore, the control unit 150 also forms a user interface that displays the operating status of the substrate stacking device 100 to the outside.

[0014] The aligner 300 has a pair of opposing stages, each holding a substrate 210. After aligning the substrates 210 held on the stages relative to each other, the aligner brings them into contact and stacks them to form a laminated substrate 230. In addition, correction of the substrate 210, which will be described later, may also be performed in the aligner 300.

[0015] Furthermore, inside the substrate stacking device 100, the substrate 210 is handled while being held in the substrate holder 220. The substrate holder 220 holds the substrate 210 by attraction using an electrostatic chuck or the like. By handling the substrate 210 integrally with the high-strength substrate holder 220, damage to the brittle substrate 210 is prevented, and the operation of the substrate stacking device 100 can be increased in speed.

[0016] The substrate holder 220 is made of a hard material such as alumina ceramics and has a holding portion having approximately the same area as the substrate 210, and an edge portion located outside the holding portion. Multiple substrate holders 220 are provided within the substrate stacking device 100 to hold each substrate 210 as it is brought in.

[0017] When the substrate 210 or the laminated substrate 230 is removed from the substrate stacking device 100, the substrate holder 220 is separated from the substrate 210 or the laminated substrate 230. Therefore, the substrate holder 220 remains inside the substrate stacking device 100 and is reused. Thus, the substrate holder 220 can be considered part of the substrate stacking device 100. Unused substrate holders 220 are stored in the holder stocker 400.

[0018] The pre-aligner 500 works in cooperation with the transport robot 140 to hold the incoming substrate 210 in the substrate holder 220. The pre-aligner 500 is also used to separate the laminated substrate 230, which has been discharged from the aligner 300, from the substrate holder 220.

[0019] In the substrate stacking apparatus 100 described above, in addition to the substrate 210 on which elements, circuits, terminals, etc. are formed, unprocessed silicon wafers, compound semiconductor wafers, glass substrates, etc., can also be joined. The joining may be between a circuit board and an unprocessed substrate, or between two unprocessed substrates. The substrate 210 to be joined may itself be a laminated structure substrate 230 that has already been formed by stacking multiple substrates.

[0020] Figure 2 is a schematic plan view of the substrate 210 to be stacked in the substrate stacking apparatus 100. The substrate 210 has a notch 214, a plurality of circuit regions 216, and a plurality of alignment marks 218.

[0021] 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.

[0022] 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.

[0023] Alignment marks 218 are an example of structures formed on the surface of substrate 210, and are placed on top of scribe lines 212 arranged between circuit regions 216. Alignment marks 218 are used as indicators when aligning substrate 210 with other substrates 210 to be stacked.

[0024] Figure 3 is a flowchart showing the procedure for manufacturing a laminated substrate structure 230 by stacking substrates 210 in a substrate stacking apparatus 100. In the substrate stacking apparatus 100, first, the pre-aligner 500 holds the substrates 211 one by one in the substrate holder 220 (step S101).

[0025] The substrate holder 221, which holds the substrate 211, is loaded into the aligner 300 together with the substrate 211 (step S102). Next, the other substrate 213, which will be stacked on top of the substrate 211, is also loaded into the aligner 300 while being held by the substrate holder 223.

[0026] Figures 4 to 8 illustrate the structure and operation of the aligner 300. First, let's explain the structure of the aligner 300.

[0027] Figure 4 is a schematic cross-sectional view showing the aligner 300 immediately after substrates 211, 213 and substrate holders 221, 223 have been loaded. The aligner 300 in the substrate stacking apparatus 100 comprises a frame 310, an upper stage 322, and a lower stage 332.

[0028] The frame 310 has a bottom plate 312 and a top plate 316 that are parallel to the horizontal floor surface 301, and a number of support columns 314 that are perpendicular to the floor plate. The bottom plate 312, support columns 314 and top plate 316 form a rectangular frame 310 that accommodates the other members of the aligner 300.

[0029] 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. In the illustrated state, the substrate 213 is already held on the upper stage 322 together with the substrate holder 223.

[0030] A microscope 324 and an 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 210 held on the lower stage 332, which is positioned opposite the upper stage 322. The activation device 326 generates plasma to clean the upper surface of the substrate 210 held on the lower stage 332. For example, oxygen plasma or nitrogen plasma can be used as the plasma. Note that the activation devices 326 and 336 may be provided separately from the aligner 300, and the substrate and substrate holder may be transported to the aligner 300 by a robot.

[0031] The lower stage 332 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. In the illustrated state, the substrate 211 is already held in the lower stage 332 together with the substrate holder 221. The substrate holder 221 continues to hold the substrate 211, and the substrate 211 remains in the corrected state.

[0032] 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.

[0033] 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. This allows the lower stage 332 to move up and down relative to the Y-direction drive unit 333.

[0034] 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 accurate and high-speed bonding of the substrate 210 mounted on the lower stage 332.

[0035] The Y-direction drive unit 333 is further equipped with a microscope 334 and an activation device 326, both mounted to the sides of the lower stage 332. The microscope 334 can observe the underside of the downward-facing substrate 210 held on the upper stage 322. The activation device 336 generates plasma to clean the underside of the substrate 210 held on the upper stage 322.

[0036] The aligner 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 210 held on the lower stage 332, thereby improving the alignment accuracy of the substrate 210.

[0037] The control unit 150 pre-calibrates the microscopes 324 and 334 relative to each other. The microscopes 324 and 334 are calibrated by aligning their focal points relative to each other, as shown in Figure 4. This allows the relative positions of the pair of microscopes 324 and 334 in the aligner 300 to be measured.

[0038] Next, as shown in Figure 5, the control unit 150 operates the X-direction drive unit 331 and the Y-direction drive unit 333 to detect the alignment marks 218 provided on each of the substrates 211 and 213 using the microscopes 324 and 334 (step S103 in Figure 3). The alignment marks 218 are detected by observing the surface of the substrate 210 with the microscopes 324 and 334. In this way, by detecting the alignment marks 218 on each of the substrates 210 using the microscopes 324 and 334, whose relative positions are known, the relative positions of the substrates 211 and 213 can be determined (step S104). Therefore, the substrates 211 and 213 can be aligned with each other based on these relative positions.

[0039] Next, as shown in Figure 6, the control unit 150 chemically activates the bonding surfaces of each of the pair of substrates 210 while remembering the relative positions of the pair of substrates 211 and 213 (step S105 in Figure 3). The control unit 150 first resets the position of the lower stage 332 to its initial position and then moves it horizontally, allowing the plasma generated by the activation devices 326 and 336 to scan the surfaces of the substrates 211 and 213. This cleans the surfaces of the substrates 211 and 213 and increases their chemical activity. As a result, the substrates 211 and 213 autonomously attract and bond to each other simply by coming close together.

[0040] In the above example, the substrate 210 held on the lower stage 332 was exposed to plasma P generated by the activation device 326 supported on the top plate 316 to clean the surface of the substrate 210. In addition, the substrate 210 held on the upper stage 322 was exposed to plasma P generated by the activation device 336 mounted on the Y-direction drive unit 333 to clean the surface of the substrate 210.

[0041] 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 substrate 210 from contaminating the microscope 324.

[0042] Furthermore, although the aligner 300 shown in the figure is equipped with activation devices 326, 326 for activating the substrate 210, it is also possible to omit the activation devices 326 of the aligner 300 by loading the substrate 210, which has been pre-activated using activation devices 326, 326 provided separately from the aligner 300, into the aligner 300.

[0043] Furthermore, in addition to exposure to plasma, the substrate 210 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 aligner 300 can be generated under reduced pressure. The substrate 210 can also be activated by ultraviolet irradiation, an ozone asher, or the like. Furthermore, it may be activated by chemically cleaning the surface of the substrate 210 using, for example, a liquid or gaseous etchant.

[0044] Next, as shown in Figure 7, the control unit 150 aligns the substrates 211 and 213 relative to each other (step S106 in Figure 3). First, 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 S103, the control unit 150 moves the lower stage 332 so that the planar positions of the alignment marks 218 on the substrates 211 and 213 coincide.

[0045] Next, as shown in Figure 8, the control unit 150 operates the lifting drive unit 338 to raise the lower stage 332, bringing the substrates 211 and 213 into contact with each other (step S107). As a result, parts of the substrates 211 and 213 come into contact and are joined together.

[0046] Furthermore, since the surfaces of substrates 211 and 213 are activated, when parts of them come into contact, the intermolecular forces between substrates 211 and 213 cause adjacent regions to autonomously attract and bond to each other. Therefore, for example, by releasing the hold of substrate 213 in the upper stage 322, the contact region of substrates 211 and 213, i.e., the region where substrates 211 and 213 are bonded, expands sequentially to adjacent regions. This generates a bonding wave in which the bonded region expands sequentially, and the bonding of substrates 211 and 213 progresses. In other words, bonding progresses as the boundary between the contact region and the non-contact region of substrates 211 and 214 moves toward the non-contact region. Eventually, substrates 211 and 213 come into contact and bonded over their entire surfaces (step S108 in Figure 3). As a result, substrates 211 and 213 form a laminated structure substrate 230.

[0047] Furthermore, as the bonding area of ​​substrates 211 and 213 expands as described above, the control unit 150 may release the substrate holder 223 from holding substrate 213. Alternatively, the upper stage 322 may release the substrate holder 223 from holding substrate 223.

[0048] Furthermore, the bonding of substrates 211 and 213 may be advanced by opening substrate 211 at the lower stage 332 without opening substrate 213 at the upper stage 322. Alternatively, substrates 211 and 213 may be bonded by bringing the upper stage 322 and the lower stage 332 closer together while holding substrates 213 and 211 at both the upper stage 322 and the lower stage 332.

[0049] The laminated substrate 230 thus formed is unloaded from the aligner 300 by the transport robot 140 (step S109) and stored in the substrate cassette 130. If the substrate holder 223 releases its hold on the upper substrate 213, the substrate holder 223 continues to be held on the upper stage 322.

[0050] At the stage of unloading the laminated substrate 230 from the aligner 300, the substrate holder 221 held on the lower stage 332 may still be holding the substrate 211. In such cases, the substrate holder 221 may be unloaded together with the laminated substrate 230, and after separating the laminated substrate 230 and the substrate holder 221 in the pre-aligner 500, the laminated substrate 230 may be transported to the substrate cassette 130.

[0051] Figure 9 shows the state of substrates 211 and 213 during the superposition process using the aligner 300 as described above. Figure 9 shows the state at step S107 in Figure 3, when substrates 211 and 213 begin to come into contact.

[0052] The substrate holders 222 and 223 have electrostatic chucks, etc., and hold the substrates 211 and 213 by adsorption across their entire surfaces. Therefore, when the holding surface is flat, as in the substrate holder 222 shown at the bottom of the figure, the substrate 211 is held flat. Also, when the surface of the holding surface is curved, such as in the substrate holder 223 shown at the top of the figure, the adsorbed substrate 213 is deformed to form such a curved surface.

[0053] Furthermore, by joining at least one of the substrates 211 and 213 in a state where it is deformed so that the inside protrudes in the planar direction of the substrates 211 and 213, as described above, the joining of the substrates 211 and 213 proceeds from the inside to the outside in the planar direction of the substrates 211 and 213. This prevents air bubbles (voids) from remaining inside the laminated substrate 230 formed by the joining.

[0054] Furthermore, when stacking substrates 211 and 213, if one substrate 211 or 213 is held and the other is left open, it is preferable to hold the substrate 211 or 213 that has a greater or more complex non-uniformity in the predicted amount of elongation, or a higher structural anisotropy, and leave the other open when stacking them. This makes it easier for the correction of the misalignment of the circuit region 216 to be reflected in the laminated substrate 230.

[0055] Furthermore, when stacking substrates 211 and 213, the aligner 300 may continue to hold substrates 211 and 213 until the bonding of substrates 211 and 213 is complete. In this case, while maintaining the positioning of substrates 211 and 213 by substrate holders 221 and 223 or a stage that holds substrates 211 and 213, substrates 211 and 213 are pressed down across their entire surface.

[0056] Figures 10 to 12 show the changes in state during the superposition process of substrates 211 and 213 shown in Figure 9, and correspond to the region indicated by the dotted line Q in Figure 9. In step S108, as the superposition process progresses, the boundary K between the contact region where substrates 211 and 213 are superimposed on each other and the non-contact region where substrates 211 and 213 are separated from each other and will be superimposed moves from the center of substrates 211 and 213 toward the periphery.

[0057] Therefore, at boundary K, the substrate 213, which is released from being held by the substrate holder 223, inevitably undergoes elongation deformation. More specifically, at boundary K, with respect to the central surface A in the thickness direction of the substrate 213, the substrate 213 elongates on the lower side in the figure and contracts on the upper side in the figure.

[0058] Figure 11 shows the state from the same viewpoint as in Figure 10, where the boundary K has moved toward the peripheral edges of substrates 211 and 213. Substrate 213, which is in contact with substrate 211, gradually expands its contact area from the central part where it initially made contact toward the peripheral edges which were initially separated from the lower substrate 211.

[0059] Furthermore, as shown by the dotted line in the figure, at the outer edge of the region joined to substrate 211, the surface of substrate 213 deforms as if it were enlarged relative to substrate 211. As a result, a positional misalignment occurs between the lower substrate 211 held by the substrate holder 222 and the upper substrate 213 released from the substrate holder 223, due to the difference in the amount of elongation of substrate 213, as shown by the dotted line misalignment in the figure. In other words, the amount of deformation of substrate 213 differs depending on the direction of expansion of the contact area between substrates 211 and 213, and this difference in deformation causes a positional misalignment between substrates 211 and 213. The direction of expansion of the contact area includes the direction perpendicular to the tangential of the boundary of the contact area, the tangential direction, and the direction along the boundary, and when substrates 211 and 213 are in contact from the center, it includes the radial direction of substrates 211 and 213 and the circumferential direction of the substrates.

[0060] Figure 12 shows a state where the bonding of substrate 213 to substrate 211 has progressed further from the state shown in Figure 12, and the bonding of substrates 211 and 213 is nearing completion. When the activated surfaces of substrates 211 and 213 come into contact with each other, they are bonded and become one. Therefore, any misalignment that occurs between substrate 211 and substrate 213 at the bonding interface is fixed by the bonding.

[0061] Figure 13 shows the amount of misalignment of substrate 211 relative to substrate 213 in a laminated substrate 230 fabricated by stacking substrates 211 and 213 through the process described above. The arrows in the figure indicate the direction of the misalignment and the magnitude of the misalignment by their length. As shown in the figure, the misalignment of substrates 211 and 213 occurs over almost the entire surface of the laminated substrate 230, and the amount of misalignment increases as you approach the periphery of the laminated substrate 230.

[0062] Therefore, the amount of misalignment varies and is not uniform across the entire substrate 211 and 213. Consequently, even if the alignment of the entire substrate 211 and 213 is adjusted in step S106 shown in Figure 3, it is not possible to eliminate the overall misalignment of the substrate 211 and 213 caused by the uneven amount of elongation.

[0063] In addition to the distribution of stiffness in the substrate, the following can also cause non-uniform deformation: When a connecting part made of a metal such as Cu is embedded in the oxide film layer formed on the surface of the substrate, a difference arises between the intermolecular forces acting between the oxide films of the two substrates and the intermolecular forces acting between the connecting part during bonding. This changes the degree of bonding wave propagation, i.e., the propagation speed and amount. In particular, if the surface of the connecting part is located below the oxide film surface, the attractive force between the connecting parts becomes smaller, and the propagation of the bonding wave slows down.

[0064] One way to prevent this is to arrange the connection points along the boundary line K shown in Figure 10, thereby aligning the timing of the bonding wave passing through multiple connection points. Alternatively, the propagation speed of the bonding wave can be controlled by placing dummy connection points that are not intended for electrical connection. Furthermore, if the substrate has a distribution of stiffness, the placement of connection points and dummy connection points may be adjusted to take this stiffness distribution into consideration.

[0065] Figure 14 is a schematic diagram showing the layout of substrate 501 modified from substrate 211 for the purpose of correcting the positional misalignment when superimposed on substrate 211. When forming circuit regions 216 across the entire substrate 501 by repeatedly exposing it using the same mask, the shot map is corrected to gradually widen the spacing of the circuit regions 216 from the center of substrate 501, which is the contact point with substrate 211, towards the periphery.

[0066] As a result, any misalignment that occurs when bonding substrate 501 to substrate 213 is corrected by the layout of substrate 501 itself, and circuit misalignment is suppressed throughout the entire laminated substrate 230. Therefore, the yield of the laminated semiconductor device obtained after dicing the laminated substrate 230 manufactured by laminating substrate 213 and substrate 501 can be improved.

[0067] Figure 15 is a schematic diagram showing the layout of substrate 502, which has been modified from substrate 211 to correct the positional misalignment when superimposed on substrate 211. When forming the circuit region 216 on substrate 502 by repeatedly exposing it using the same mask, the exposure pattern is optically controlled so that the magnification of the structures on substrate 502 gradually increases from the center of substrate 502, which is the contact point with substrate 213, toward the periphery, that is, along the direction of propagation of the bonding wave. The direction of propagation of the bonding wave includes the direction along the radial direction of substrates 211 and 213, which is the direction of expansion of the contact area of ​​substrates 211 and 213. Therefore, on substrate 502, the magnification of the structures on the surface of substrate 502 increases as you approach the periphery of substrate 502.

[0068] As a result, any misalignment that occurs when bonding substrate 502 to substrate 213 is corrected by the layout of substrate 502 itself, and circuit misalignment is suppressed throughout the entire laminated substrate 230. Therefore, the yield of the laminated semiconductor device obtained after dicing the laminated substrate 230 manufactured by laminating substrate 213 and substrate 502 can be improved.

[0069] In the examples shown in Figures 14 and 15, the deformation of the substrate 501 in the 45° direction is greater than the deformation in the 0° and 90° directions, so the shot spacing in the 45° direction was adjusted. However, if the deformation of the substrate 501 is equal or close in all directions, the shot spacing and shot shape can be adjusted similarly in all directions. Also, in Figures 14 and 15, if multiple chips are formed within a single shot, the spacing and shape between the multiple chips within a single shot may be adjusted to change from the center of the substrate 501 or substrate 502 towards the periphery.

[0070] Furthermore, for example, if the amount of deformation in one direction of the substrate 502 is greater than the amount of deformation in other directions, the substrate may be exposed in a deformed state to compensate for the difference in deformation, and then the deformation may be released after exposure to compensate for the difference in deformation. For example, if the upper side in the figure where the notch 214 is provided is set to 0 degrees, and it is found that the amount of radial deformation at 45-degree intervals is greater than the amount of deformation in other directions, the substrate 502 may be exposed in a state where it is contracted in each radial direction of 45 degrees, 135 degrees, 225 degrees, and 315 degrees using an actuator or the like, to transfer the pattern of the circuit region 216.

[0071] In this case, when shrinking the substrate 502, the substrate 502 can be kept flat while shrinking, thereby preventing misalignment of the circuit region 216 due to exposure. One such shrinking method is to shrink the substrate 502 while the substrate holder is bent, and then release the bent state of the substrate holder and return the substrate holder to its flat position, thereby shrinking the substrate 502 while keeping it flat.

[0072] Subsequently, by releasing the deformation of the substrate 502 caused by the actuator, the contraction of the substrate 502 can be eliminated, thereby correcting a specific amount of radial deformation in the substrate 502. The amount of deformation of the substrate 502 during exposure is determined according to the amount of correction to be made in the substrate 502.

[0073] Furthermore, while the correction for regions corresponding to directions of travel with large deformation of the substrate 213 was performed using regions corresponding to directions of travel with small deformation as a reference, it is also possible to correct regions with small deformation using regions with large deformation as a reference. In addition, positional misalignment occurring in regions with deformation amounts that differ from the reference deformation amount by a predetermined value or more is corrected. In this case, the predetermined value is the value at which electrical connection is lost between the connection parts of the two substrates due to the positional misalignment, and if the difference is less than the predetermined value, the connection parts remain connected.

[0074] Incidentally, the non-uniformity of elongation that causes the displacement of the circuit region 216 on substrates 211 and 213 can also be caused by factors other than those dependent on the radial direction of substrates 211 and 213. Figures 16 and 17 illustrate the relationship between crystal orientation and Young's modulus in silicon single-crystal substrates 208 and 209.

[0075] As shown in Figure 16, in the silicon single crystal substrate 208 with the (100) plane as its surface, in an XY coordinate system where the direction of the notch 214 relative to the center is 0°, the Young's modulus is high at 169 GPa in the 0° and 90° directions, while in the 45° direction, it is low at 130 GPa. Therefore, in the substrate 210 fabricated using the silicon single crystal substrate 208, a non-uniform distribution of bending stiffness occurs in the circumferential direction of the substrate 210. That is, the bending stiffness of the substrate 210 differs depending on the direction in which the bonding wave propagates from the center to the periphery of the substrate 210. Bending stiffness indicates how easily the substrate 210 deforms under bending force, and may also be expressed as the modulus of elasticity.

[0076] As explained with reference to Figures 10 to 12, the regions in the substrate 210 shown in Figure 2 have different bending stiffnesses because the magnitude of deformation that occurs during the process of overlapping and joining a pair of substrates 211 and 213 differs according to the bending stiffness. Therefore, in the laminated substrate 230 manufactured by stacking substrates 211 and 213, a non-uniform displacement of the circuit region 216 occurs in the circumferential direction of the laminated substrate 230.

[0077] Furthermore, as shown in Figure 17, in the silicon single crystal substrate 209 with the (110) plane as its surface, in an XY coordinate system where the direction of the notch 214 relative to the center is 0°, the Young's modulus is highest in the 45° direction, followed by the Young's modulus in the 0° direction. Moreover, in the 90° direction, the Young's modulus of the silicon single crystal substrate 209 is lowest. As a result, in the substrate 210 fabricated using the silicon single crystal substrate 209, a non-uniform and complex distribution of bending stiffness occurs in the circumferential direction of the substrate 210. Therefore, similar to the silicon single crystal substrate 208 shown in Figure 16, when substrates 211 and 213 are stacked and manufactured, a non-uniform displacement of the circuit region 216 occurs in the circumferential direction of the stacked structure substrate 230.

[0078] Thus, when manufacturing a laminated substrate 230 by stacking substrates 211 and 213 made using silicon single crystal substrates 208 and 209, a misalignment of the circuit region 216 occurs due to the non-uniform amount of elongation in the circumferential direction. Therefore, before stacking and joining substrates 211 and 213, the misalignment of the circuit region 216 caused by the non-uniform amount of elongation of substrates 211 and 213 is corrected.

[0079] Figures 16 and 17 show an example where the notch 214 is positioned at 0°, but the position of the notch 214 only needs to be such that the crystal orientation of the silicon single crystal substrates 208 and 209 can be determined, and it is sufficient if it is positioned at a predetermined location relative to the crystal orientation. In addition, although the XY coordinates were set based on the notch 214, the XY coordinates may also be set based on the crystal orientation of the silicon single crystal substrates 208 and 209 themselves. Furthermore, Figures 16 and 17 show the bending stiffness of the silicon single crystal substrates 208 and 209 in the 0°, 45°, and 90° directions, but if, for example, a silicon single crystal substrate whose crystal orientation does not coincide with the 0°, 45°, and 90° directions is used, the bending stiffness relative to the crystal orientation may be used.

[0080] Furthermore, as described above, when substrates 211 and 213 having anisotropic elongation are stacked while being held by substrate holders 221 and 223 or the stage of the aligner 300, the crystal orientations of the substrates 211 and 213 may be different. For example, a circuit region 216 may be formed on substrates having the same crystal orientation at a 45° offset and then stacked. In this case, the displacement of the circuit region 216 caused by the anisotropy of the rigidity of the substrates 211 and 213 will only be a 45° rotation in direction and will not manifest as a positional displacement. Alternatively, a circuit region may be formed on substrates 211 and 213 having different crystal orientations and then stacked. In this way, other nonlinear displacements due to crystal orientation, etc., can also be corrected by shifting the crystal orientation, depending on the combination.

[0081] Another cause of uneven elongation in substrates 211 and 213 is variation in their thickness. In substrates 211 and 213, areas with greater thickness have higher bending rigidity, while areas with thinner thickness have lower bending rigidity. Therefore, if substrates 211 and 213 are stacked without correction, misalignment of the circuit region 216 occurs due to uneven elongation corresponding to the thickness distribution.

[0082] Furthermore, the bending rigidity of substrates 211 and 213 is also influenced by the structure of the circuit regions formed on substrates 211 and 213. On substrates 211 and 213, the circuit regions 216, where elements, wiring, protective films, etc., are deposited, have higher bending rigidity compared to the scribe lines 212, where nothing is formed except for alignment marks 218. Since the scribe lines 212 are formed in a grid pattern on substrates 211 and 213, their rigidity is low for bending that creates folds parallel to the scribe lines 212, and high for bending that creates folds that intersect with the scribe lines 212.

[0083] Thus, structures formed on the surfaces of substrates 211 and 213 can also cause non-uniformity in the amount of elongation when they are stacked. However, in other words, the layout of structures on substrates 211 and 213 can also compensate for the non-uniformity in the bending stiffness of substrates 211 and 213.

[0084] For example, bending rigidity can be reinforced by placing dummy pads, bumps, or other connection points in the empty areas of substrates 211 and 213. Furthermore, non-uniformity in bending rigidity can be corrected by adjusting the density and arrangement of structures such as bumps and circuits within a single chip. For instance, the density of structures within the chip can be reduced in areas with high bending rigidity, while the density can be increased in areas with low bending rigidity.

[0085] Furthermore, even in areas where other elements, wiring, etc., are formed, the bending rigidity of the substrate can be compensated for by forming protective films, insulating films, etc., and adjusting their thickness and materials. In addition, the shape of the scribe lines 212 may be made into a shape other than a grid formed by straight lines to alleviate the anisotropy of the rigidity of the substrates 211 and 213 caused by the scribe lines 212. Also, for example, in the silicon single crystal substrate 208 shown in Figure 16, if the bending rigidity in the 45° direction is low, and the amount of displacement, i.e., deformation, relative to the superimposed substrate is larger than in the 0° and 90° directions, the positional displacement of the circuit region 216 caused by the non-uniform elongation of the substrates 211 and 213 can be corrected by changing the spacing and shape of the shots and chips from the center to the periphery of the silicon single crystal substrate 208, as shown in Figures 14 and 15. This makes it possible to keep the amount of positional displacement between a pair of superimposed substrates within a predetermined range in which the circuits of the pair of substrates are joined to each other.

[0086] Furthermore, in substrates 211 and 213, the bending stiffness may differ from region to region due to residual stresses resulting from the stresses generated during the process of forming the circuit region 216 and the process of forming an oxide film on the substrate surface. Moreover, if deformation such as warping occurs in substrates 211 and 213 during the process of forming the circuit region 216, non-uniformity of bending stiffness will occur in each region where warping has occurred, depending on the deformation. The uniformization of bending stiffness by the above-mentioned structure can also be used to correct such non-uniformity of bending stiffness caused by the condition of the substrates 211 and 213 themselves.

[0087] When correcting for misalignment, the amount of correction can be determined, for example, by using a substrate stacking device 100 to create a test piece with the same specifications as the product, and then measuring the amount of misalignment that occurred in the circuit region 216. By using the measured value obtained in this way to perform correction, corrections that are in line with the product can be effectively carried out.

[0088] Furthermore, by pre-determining the combinations of substrates 211 and 213 to be superimposed on each other and then correcting the substrates 211 and 213 accordingly, it may be possible to cancel out the unevenness in the amount of elongation in each substrate 211 and 213, thereby reducing the amount of correction required for misalignment. Conversely, by completely correcting the misalignment in each of the substrates 211 and 213, it is also possible to eliminate any constraints on the combinations of substrates 211 and 213 to be superimposed.

[0089] Furthermore, by detecting or predicting the stiffness distribution of each substrate 211 and 213 in advance, the substrates 211 and 213 may be aligned with each other in such a way that the sum of their stiffness values ​​is equal, or that the sum of their stiffness values ​​falls within a predetermined range. In this case, the positions of structures such as shots, chips, and circuits on the other substrate may be formed according to the stiffness distribution based on the crystal anisotropy of one of the two superimposed substrates.

[0090] Furthermore, when stacking substrates with the same or similar crystal orientations, by stacking regions where the stiffness or elastic modulus for bending is the same or similar, i.e., regions where the difference in stiffness or elastic modulus is below a predetermined threshold, the difference in deformation amount due to the stiffness distribution between the substrates can be suppressed. Here, the predetermined threshold is the value at which electrical connection between the two substrates is lost due to the misalignment caused by the difference in stiffness; if it is greater than the threshold, the connection between the substrates will not be made. In this case, it is preferable to partially bring the pair of substrates into contact while holding them on a stage or substrate holder, and then release each of the substrates from their respective positions.

[0091] Furthermore, if one substrate undergoes nonlinear scaling deformation due to stress generated during circuit formation or oxide film formation, the other substrate should be selected such that the deformation state generated during the bonding wave process matches that of the first substrate; that is, the position of the circuit on the second substrate should match that of the circuit on the first substrate as a result of the deformation. By selecting a substrate with a stiffness distribution that corresponds to the deformation state of the substrate with initial deformation, positional misalignment between the substrates can be suppressed. In this case, it is preferable to fix the first substrate to a stage or substrate holder and then bond it to the first substrate by releasing the other substrate's hold.

[0092] Furthermore, a pressure adjustment unit may be provided to adjust the atmospheric pressure around at least one of the pair of substrates 211, 213. The pressure adjustment unit can control the amount of deformation of at least one of the pair of substrates 211, 213 by adjusting the amount of gas present in the pair of substrates 211, 213 according to the deformation distribution of one of the substrates 211, 213. For example, by reducing the pressure around the pair of substrates 211, 213, the pressure received from the gas present between the pair of substrates 211, 213 can be reduced. This reduces the amount of deformation of the substrate 211 due to this pressure. For example, in the silicon single crystal substrate 208 shown in Figure 16, if the bending rigidity in the 45° direction is low, and the amount of displacement, i.e., deformation, relative to the superimposed substrate is larger than in the 0° and 90° directions, reducing the pressure around the region in the 45° direction can reduce the difference in deformation between the regions in the 0° and 90° directions.

[0093] Furthermore, by adjusting the activation level of at least one of the pair of substrates 211 and 213, the non-uniformity of the deformation amount caused by the stiffness distribution of that substrate can be suppressed. For example, in the silicon single crystal substrate 208 shown in Figure 16, if the deformation amount is larger in the 45° direction than in the 0° and 90° directions due to low bending stiffness in the 45° direction, increasing the activation level in the 45° region improves the adsorption force to the other substrate compared to the 0° and 90° regions. This allows the deformation amount in the 45° region to be adjusted. In this case, it is preferable to release the substrate whose activation level is being adjusted from the stage or substrate holder, and to keep the other substrate in the stage or substrate holder. The activation level is adjusted by adjusting the plasma irradiation time, plasma irradiation amount, elapsed time after activation, and plasma type, etc. That is, the activation level can be increased by lengthening the irradiation time, increasing the irradiation amount, or shortening the elapsed time.

[0094] Furthermore, in addition to the corrections made on each of the substrates 211 and 213 as described above, the non-uniformity of the elongation of the substrates 211 and 213 can also be corrected at the stage when the substrates 211 and 213 are stacked. Figure 18 is a schematic diagram of the correction unit 601 in the aligner 300 that can correct the non-uniformity of the elongation at the stage when the substrates 211 and 213 are stacked. Moreover, an optimal junction solution that takes into account the pattern arrangement of HOT (Hybrid-Orientation Technology) considering the optimal surface orientation of the PMOS and NMOS components of the CMOS may also be used.

[0095] Figure 18 is a schematic diagram of a correction unit 601 that can be used to correct substrates 211 and 213 in the aligner 300. The correction unit 601 is incorporated into the lower stage 332 in the aligner 300.

[0096] The correction unit 601 includes a base 411, a plurality of actuators 412, and a suction unit 413. The base 411 supports the suction unit 413 via the actuators 412. Multiple actuators 412 are arranged in the planar direction of the lower stage 332 and, under the control of the control unit 150, are individually supplied with working fluid from the outside through pumps 415 and valves 416, and each extends and retracts with a different amount of action.

[0097] The suction unit 413 has a suction mechanism such as a vacuum chuck or an electrostatic chuck, and suctions the substrate holder 221, which holds the substrate 211, to its upper surface. As a result, the substrate 211, the substrate holder 221, and the suction unit 413 become one integrated unit.

[0098] Furthermore, the suction section 413 is connected to multiple actuators 412 via links. The center of the suction section 413 is also connected to the base 411 by a support column 414. When the actuators 412 operate in the correction section 601, each region to which the actuators 412 are connected is displaced in the thickness direction of the lower stage 332.

[0099] Figure 19 is a schematic plan view of the correction unit 601, showing the layout of the actuators 412 in the correction unit 601. In the correction unit 601, the actuators 412 are arranged radially around the support column 414. Alternatively, the arrangement of the actuators 412 can be considered as concentric circles around the support column 414. The arrangement of the actuators 412 is not limited to that shown in Figure 19; for example, they may be arranged in a grid pattern.

[0100] Figure 20 is a diagram illustrating the operation of the correction unit 601. As shown in the figure, with the substrate holder 221 holding the substrate 211 attached to the suction unit 413, the substrate 211 can be deformed at the lower stage 332 of the aligner 300 by individually opening and closing the valves 416.

[0101] As shown in Figure 19, the actuators 412 can be considered to be arranged concentrically, that is, in the circumferential direction of the lower stage 332. Therefore, as shown by the dotted line M in Figure 19, by grouping the actuators 412 around the circumference and increasing the amount of extension as they approach the center, the surface of the suction part 413 can be made to bulge in the center, as shown in Figure 20, and deformed into a sphere, parabolic surface, etc. As a result, the substrate holder 221 and the substrate 211 held by the suction part 413 are also deformed into a sphere, parabolic surface, etc.

[0102] Figure 21 is a schematic diagram illustrating the correction performed by the correction unit 601. In Figure 20, similar to Figure 9, parts of the substrates 211 and 213 in the superposition process are shown.

[0103] During the superposition process, as already explained with reference to Figures 10-12, the substrate 213 superimposed on the substrate 211 undergoes deformation at the boundary K between the area already superimposed on the substrate 211 and the area detached from the substrate 211 and yet to be superimposed. In contrast, when the correction unit 601 is in operation, the central side of the substrate 211 protrudes more than the outer edge, and the substrate 211 as a whole forms a sphere or parabolic surface. Therefore, as shown by the dotted line in the figure, the upper surface of the substrate 211 joined to the substrate 213 expands compared to the flat state.

[0104] In this way, the operation of the correction unit 601 causes deformation that stretches the joint surfaces of both substrates 211 and 213, thereby correcting the misalignment of the circuit region 216 between the substrates 211 and 213. In the correction unit 601, each actuator 412 can be controlled individually. Therefore, even if the distribution of the amount of elongation of the substrate 211 to be corrected is non-uniform, correction can be performed with different correction amounts for each region of the substrate 211. The drive amount, i.e., the displacement amount, of the multiple actuators 412 is set according to the amount of misalignment between the substrates 211 and 213 caused by the difference in the amount of deformation in at least one plane of the substrates 211 and 213. At this time, as described above, the result of the amount of misalignment when experimentally joining substrates of equivalent use to the two substrates 211 and 213 to be joined may be used.

[0105] For example, similar to the silicon single crystal substrate 208 shown in Figure 16, if the amount of displacement is larger in the substrate 213 due to low bending rigidity in the 45° direction compared to the 0° and 90° directions, the actuator 412 is controlled so that the height position of the portion of the substrate holder 221 corresponding to the 45° region of the substrate 213 is relatively higher than the height position of the portion corresponding to the 0° and 90° regions. This makes it possible to thin the air layer between the 45° region of the substrate 213 and the corresponding region of the substrate 211, thereby reducing the resistance received from that air layer, and thus reducing the difference in in-plane deformation caused by the non-uniformity of the rigidity distribution of the silicon single crystal substrate 208.

[0106] Alternatively, if the amount of displacement is greater in the 45° direction due to low bending rigidity in the substrate 213 compared to the 0° and 90° directions, the 45° region of the substrate 211 is extended by making the height position of the portion of the substrate holder 221 corresponding to the 45° region of the substrate 213 relatively lower than the height position of the portion corresponding to the 0° and 90° regions. This height difference is set according to the amount of deformation in the 45° region of the substrate 213.

[0107] Figure 22 shows another distribution of the displacement of the circuit region 216 in the laminated substrate 230 caused by the non-uniform distribution of elongation. The displacement caused by differences in the crystal orientation of the substrate, differences in physical properties at the scribe lines, etc., is distributed parallel to each other in the laminated substrate 230, as shown by the dotted line R in the figure.

[0108] Figure 23 shows a method by which the correction unit 601 corrects for anisotropy in the distribution of misalignment, as described above. As shown in the figure, when correcting misalignment distributed in a specific direction, the actuators 412 arranged in a line are extended, as shown by the dotted line N in Figure 19, to deform the adsorption part 413 of the correction unit 601 into a cylindrical shape. For example, if this misalignment is caused by the crystal orientation of the substrate and the crystal direction is along the dotted line R in Figure 22, the substrate 211 is curved along a line perpendicular to the dotted line R. As a result, the direction of propagation of the bonding wave of the substrate superimposed on the substrate 211 is aligned with the crystal direction. This causes deformation in the substrate 211 that extends only in the circumferential direction of the cylindrical surface formed by the adsorption part 413. This makes it possible to correct misalignment in a specific direction on the substrate 211.

[0109] Furthermore, when the correction unit 601 is used, the correction amount can be continuously changed according to the amount of working fluid supplied to the actuator 412. However, when stacking a large number of substrates 211 with the same correction method and correction amount, the substrates 211 can be stacked while correcting the misalignment amount using a simple aligner 300 without the correction unit 601 by providing a substrate holder 221 that holds the substrates 211 with a holding surface having a shape that reflects the correction amount. Alternatively, the substrate holder 221 may be given characteristics that reduce the non-uniformity of the elongation amount of the substrates 211, and the non-uniform elongation amount may be corrected by holding the substrates 211 in the substrate holder 221.

[0110] For example, by holding the substrate 211 with a substrate holder 221 that has low rigidity in areas corresponding to areas with high bending rigidity of the substrate 211, and high rigidity in areas corresponding to areas with low bending rigidity of the substrate 211, the difference in bending rigidity within the plane of the substrate 211 can be kept within a predetermined range. This predetermined range is the range in which, even when deformation occurs in the substrate 211 during bonding wave, the circuit in at least the low-rigidity region of the substrate 211 and the circuit of the substrate on which the substrate 211 is superimposed can be bonded to each other.

[0111] Furthermore, the above example described the case where the correction unit 601 is provided on the lower stage 332. However, the correction unit 601 may also be provided on the upper stage 322 to correct the upper substrate 213 in the figure. Moreover, the correction unit 601 may be provided on both the lower stage 332 and the upper stage 322 to perform correction on both substrates 211 and 213. Furthermore, other correction methods already described, or other correction methods to be described later, may be used in combination with the above correction method.

[0112] Furthermore, instead of the substrate holder 221, or in addition to the substrate holder 221, the holding surface of the holding part such as a stage that holds the substrate 211 may be a curved surface that reflects the target correction amount. Moreover, even when the substrates 211 are stacked without using the substrate holder 221, the non-uniformity of the elongation of the substrate 213 can be suppressed by making the holding surface of the holding part such as a stage that holds the substrate 211 a curved surface that reflects the target correction amount.

[0113] Alternatively, in addition to or instead of any of the above methods, misalignment caused by uneven deformation during bonding may be corrected by adjusting the temperature of the substrate 211. In this case, for example, if the deformation of the 45-degree portion of the substrate is greater than that of other portions, this portion may be heated to expand it, or the portions other than the 45-degree portion may be cooled to contract them.

[0114] Figure 24 is a schematic cross-sectional view of another correction unit 602, showing one example of controlling the progression of contact with substrate 213 in a region corresponding to a direction of travel where the amount of deformation of one substrate 211 is greater than in other directions of travel. The correction unit 602 is incorporated into a substrate holder 223 used in the upper stage 322 of the aligner 300.

[0115] The correction unit 602 is provided in the substrate holder 223 and includes a plurality of openings 426 that open toward the substrate 213 held by the substrate holder 223. One end of each opening 426 communicates with a pressure source via a valve 424 through the upper stage 322. The pressure source 422 is a pressurized fluid, such as compressed dry air. The valves 424 are opened and closed individually under the control of the control unit 150. When a valve 424 is opened, pressurized fluid is injected from the corresponding opening 426.

[0116] Figure 25 shows the layout of the opening 426 in the correction unit 602. The opening 426 is located across the entire holding surface of the substrate holder 223 that holds the substrate 213. Therefore, by opening any of the valves 424, pressurized fluid can be injected downwards in the figure at any position on the holding surface of the substrate holder 223.

[0117] The substrate holder 223 holds the substrate 213, for example, by an electrostatic chuck. The electrostatic chuck's holding force can be released by cutting off the power supply, but there is a time lag before the substrate 213 is released due to residual charge, etc. Therefore, immediately after cutting off the power supply to the electrostatic chuck, pressurized fluid can be injected from the opening 426 of the entire substrate holder 223 to instantly release the substrate 213.

[0118] Figure 26 is a schematic diagram illustrating the correction operation of the correction unit 602. In Figure 26, as in Figure 9, parts of the substrates 211 and 213 in the superposition process are shown.

[0119] During the superposition process, as already explained with reference to Figures 10-12, the substrate 213 superimposed on the substrate 211 undergoes deformation at the boundary K between the region already superimposed on the substrate 211 and the region that is detached from the substrate 211 and yet to be superimposed. At this boundary K, pressurized fluid 427 is injected from above by the correction unit 602 into the region of the substrate 213 where deformation is occurring. This causes the substrate 213 to be pushed toward the other substrate 211, reducing the amount of deformation. This allows for correction to reduce the amount of elongation of the substrate 213 at the point where the pressurized fluid is injected.

[0120] In this way, the correction unit 602 can suppress elongation deformation in the substrate 213, thereby correcting the misalignment of the circuit region 216 caused by uneven elongation between the substrates 211 and 213. In the correction unit 602, pressurized fluid can be individually injected into the openings 426. Therefore, even if the distribution of elongation of the substrate 213 to be corrected is uneven, correction can be performed with different correction amounts for each region of the substrate 213.

[0121] Therefore, in the aligner 300 equipped with the correction unit 602, the non-uniformity of stiffness can be checked in advance based on information such as the crystal orientation of the substrate 213, the arrangement of structures, and the thickness distribution. For example, in the substrate 213, pressurized fluid can be blown from the opening 426 to the region with the larger displacement between the region with low bending stiffness and the region with high bending stiffness, thereby correcting the elongation of the substrate 213. This makes it possible to suppress the positional displacement of the circuit region 216 in the laminated structure substrate 230 made by stacking substrates 211 and 213.

[0122] For example, if the amount of displacement is greater in the region of the substrate 213 where the bending rigidity is high, and the amount of protrusion or curvature of the correction section 602 shown in Figure 21 is determined based on the low-rigidity region in order to compensate for the amount of displacement in the region of the substrate 213 where the bending rigidity is low, then the amount of displacement in the high-rigidity region can be reduced by spraying pressurized fluid into the high-rigidity region.

[0123] In the above example, the case in which the correction unit 602 is provided on the upper stage 322 was described. However, in an aligner 300 in which the substrate 211 held on the lower stage 332 deforms, the correction unit 602 may be provided on the lower stage 332 to correct the amount of elongation of the lower substrate 211 in the figure. Furthermore, the correction unit 602 may be provided on both the lower stage 332 and the upper stage 322 to perform correction on both substrates 211 and 213.

[0124] Furthermore, other correction methods already described, or other correction methods to be described later, may be used in combination with the above correction method. In addition, the correction unit 602 can also be incorporated into the aligner 300 together with the correction unit 601 shown in Figure 18.

[0125] Figure 27 is a schematic cross-sectional view of another correction unit 603. The correction unit 603 is incorporated into the substrate holders 221 and 223 used in the aligner 300.

[0126] The correction unit 603 includes a switch 434, an electrostatic chuck 436, and a voltage source 432. The electrostatic chucks 436 are embedded in the substrate holders 221 and 223. Each of the electrostatic chucks 436 is coupled to a common voltage source 432 via an individual switch 434. As a result, each of the electrostatic chucks 436 generates an attractive force on the surface of the substrate holders 221 and 223 when the switch 434, which is opened and closed under the control of the control unit 150, is closed, thereby attracting the substrates 211 and 213.

[0127] The electrostatic chucks 436 in the correction unit 603 are arranged across the entire holding surface of the substrate holders 221 and 223 that hold the substrate 213, similar to the opening 426 of the correction unit 602 shown in Figure 25. As a result, each of the substrate holders 221 and 223 has multiple suction areas. Therefore, when any of the switches 434 are closed, the corresponding electrostatic chucks 436 generate suction force, applying suction force to the substrates 211 and 213 at any position on the holding surface of the substrate holder 223. When all switches 434 are closed, all electrostatic chucks 436 generate suction force, firmly holding the substrates 211 and 213 in the substrate holders 221 and 223.

[0128] Figure 28 is a diagram illustrating the correction operation of the correction unit 603. In Figure 28, as in Figure 9, parts of the substrates 211 and 213 in the process of superposition are shown.

[0129] During the superposition process, as already explained with reference to Figures 10-12, the substrate 213 superimposed on the substrate 211 undergoes deformation at the boundary K between the region already superimposed on the substrate 211 and the region detached from the substrate 211 and yet to be superimposed. The lower surface of the substrate 213, which is joined to the substrate 211, undergoes elongation. Here, if the correction unit 603 applies an adhesive force to the substrate 213 from above in the region near the boundary K where deformation is occurring, a larger deformation occurs in the substrate 213 compared to the deformation without correction, as shown by the dotted line in the figure. This allows for a correction that increases the amount of elongation of the substrate 213 at the point where the electrostatic chuck 436 is operated.

[0130] This correction is applied to areas where the amount of displacement, i.e., deformation, due to the rigidity distribution of the substrate is large. For example, in the silicon single crystal substrate 208 shown in Figure 16, if the amount of displacement is larger in the 45° direction than in the 0° and 90° directions due to low bending rigidity in the 45° direction, the suction force of the electrostatic chuck 436 corresponding to the 45° direction among the multiple electrostatic chucks 436 of the substrate holder 223 is made greater than the suction force of the electrostatic chucks 436 corresponding to the 0° and 90° directions.

[0131] Furthermore, in the process of stacking the pair of substrates 211 and 213 on top of each other by releasing the suction of the substrate 213 to the substrate holder 223, if the substrate holder 221 in the lower stage 332 partially releases its hold on the substrate 211, the lower substrate 211 will lift up from the substrate holder 221 in that region, following the upper substrate 213. This reduces the deformation of the lower substrate 211, allowing for a correction that further reduces the amount of elongation.

[0132] This correction is applied to areas where the amount of displacement, i.e., deformation, is large due to the rigidity distribution of the substrate. For example, in the silicon single crystal substrate 208 shown in Figure 16, if the amount of displacement is larger in the 45° direction than in the 0° and 90° directions due to low bending rigidity in that direction, the electrostatic chuck 436 of the substrate holder 221 corresponding to the 45° direction is sequentially released in accordance with the progress of contact between the pair of substrates 211 and 213. In this way, by setting, changing, and controlling the holding force on the substrate 211 held by the lower stage 332 according to the rigidity distribution of the substrate 211, the difference in deformation due to the rigidity distribution within the substrate can be reduced.

[0133] In this way, the correction unit 603 can promote or suppress elongation deformation in the substrates 211 and 213. Furthermore, the electrostatic chucks 436 arranged around the substrate holders 221 and 223 can individually generate or block suction force. Therefore, even if the non-uniformity of the elongation amount in the substrates 211 and 213 is intricately distributed, it can be corrected by the correction unit 603.

[0134] In the above example, the upper stage 322 suddenly released its grip on the substrate 213 from the substrate 211 held by the lower stage 332, causing the substrates 211 and 213 to overlap due to the autonomous bonding of the substrates 213. However, the suction force of the electrostatic chuck 436 may be sequentially reduced from the center of the substrate outward in the planar direction of the upper stage 322 to suppress the autonomous bonding of the substrate 213 and control the expansion of the area where substrates 211 and 213 are bonded, i.e., the degree of contact progression. This prevents the accumulation of misalignment as one approaches the periphery and suppresses the uneven distribution of misalignment.

[0135] In this way, by setting, changing, and controlling the holding force on the substrate 211 held by the upper stage 322 according to the stiffness distribution of the substrate 211, the difference in deformation amount caused by the stiffness distribution within the substrate can be reduced. Furthermore, although the above example shows the substrate being held by an electrostatic chuck, the substrate may be held by a vacuum chuck instead, or in addition to this.

[0136] In this case, the density of pins provided on the holding surface that holds the substrate may be set according to the rigidity distribution of the substrate. For example, in the silicon single crystal substrate 208 shown in Figure 16, if the amount of displacement is larger in the 45° direction than in the 0° and 90° directions due to low bending rigidity in the 45° direction, the adsorption force to the 45° region can be reduced by making the density of pins placed at positions corresponding to the 45° direction smaller than the density of pins placed at positions corresponding to the 0° and 90° directions.

[0137] Furthermore, in the above method, instead of adjusting the pin density, or in addition to adjusting the pin density, the suction force when holding the substrate 211 may be adjusted. For example, the holding surface for holding the substrate 211 may be divided into multiple regions, and the suction force may be changed for each region in accordance with the amount of deformation of the substrate. This allows, for example, if the notch 214 is oriented at 0 degrees, and the amount of deformation in the 45-degree direction is large, the suction force in the four regions corresponding to that portion to be reduced compared to the suction force in the other regions. This compensates for the large deformation in certain areas.

[0138] Furthermore, even when the substrates 211 and 213 are stacked by continuing to hold the substrate 213 with the upper stage 322 and releasing the holding of the substrate 211 with the lower stage 332, the amount of elongation of the substrates 211 and 213 can be corrected using the correction unit 603 in the same manner as described above.

[0139] Furthermore, if one of the substrates to be superimposed on the other is, for example, a silicon single-crystal substrate 209 with complex crystal orientation as shown in Figure 17, or a substrate that has experienced large initial strain or significant warping deformation during circuit formation or oxide film formation, it is desirable to fix such a substrate to the lower stage 332. This simplifies the control of displacement correction.

[0140] Furthermore, other correction methods already described, or other correction methods to be described later, may be used in combination with the above correction method. In addition, the correction unit 602 can be incorporated into the aligner 300 together with the correction unit 601 shown in Figure 18 and the correction unit 602 shown in Figure 24.

[0141] In this way, by correcting the substrates 211 and 213 individually, or by correcting them at the stage when the substrates 211 and 213 are stacked, the misalignment of the circuit region 216 caused by uneven elongation in the substrates 211 and 213 can be suppressed or prevented. As a result, the laminated substrate 230 can be manufactured with a high yield.

[0142] In the above example, the centers of the superimposed substrates 211 and 213 were initially brought into contact. However, if simultaneous contact at multiple locations can be avoided, the substrates 211 and 213 may be brought into contact from other locations, such as the edges. In this case, similar to the above example, one of the superimposed substrates 211 and 213 may be pre-deformed according to the deformation distribution of the other substrate from which the holding is released, i.e., the direction of the bonding wave propagation and the direction in which the contact area of ​​substrates 211 and 213 expands, or the propagation of the bonding wave on the other substrate may be controlled. At this time, it is preferable to align the crystal direction and stress / strain direction of the substrate from which the holding to the stage or substrate holder is released with the direction of the bonding wave propagation. For example, in the silicon single crystal substrate 208 shown in Figure 16, by aligning the 0° direction with the direction of the bonding wave propagation, the amount of elongation of the silicon single crystal substrate 208 generated during the bonding wave becomes uniform. This makes it possible to reduce the difference in the amount of deformation within the silicon single crystal substrate 208 caused by the stiffness distribution.

[0143] Furthermore, the shape of the boundary K that expands from the initial contact point as the substrates overlap may be a linear, elliptical, or other shape. Also, although the above example was described as correcting existing substrates 211 and 213, care may be taken to ensure that there are no inconsistencies in mechanical specifications such as bending rigidity when designing and manufacturing substrates 211 and 213.

[0144] In the above example, a silicon single-crystal substrate was used as an example for explanation. However, although this embodiment shows an example where the substrate is made of silicon single crystal, the substrate to be superimposed is not limited to a silicon single-crystal substrate. Other examples of substrates include a SiGe substrate with added Ge, a Ge single-crystal substrate, and so on. Furthermore, the present invention can also be applied to compound semiconductor substrates such as those of the III-V or II-VI groups.

[0145] Furthermore, in this embodiment, "bonding" refers to the state in which terminals provided on two substrates laminated by the method of this embodiment are connected to each other, thereby ensuring electrical conductivity between the two substrates 210, or when the bonding strength of the two substrates exceeds a predetermined strength. It also refers to the state in which the two substrates are temporarily bonded, i.e., provisionally bonded, when the two substrates laminated by the method of this embodiment are subsequently subjected to a process such as annealing, resulting in the two substrates being electrically connected or the bonding strength of the two substrates exceeding a predetermined strength. The provisionally bonded state includes a state in which the two overlapping substrates can be separated and reused.

[0146] 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 also be apparent from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0147] 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]

[0148] 100 Substrate stacking device, 110 Housing, 120, 130 Substrate cassette, 140 Transport robot, 150 Control unit, 208, 209 Silicon single crystal substrate, 210, 211, 213, 501, 502 Substrate, 212 Scribe line, 214 Notch, 216 Circuit area, 218 Alignment mark, 220, 221, 222, 223 Substrate holder, 426 Opening, 230 Laminated structure substrate, 300 Aligner, 301 Floor surface, 310 Frame, 312 Bottom plate, 314 Support column, 316 Top plate, 322 Upper stage, 324, 334 Microscope, 326, 336 Activation device, 331 X-direction drive unit, 332 Lower stage, 333 Y-direction drive unit, 338 Lifting drive unit, 400 Holder stocker, 411 base, 412 actuator, 413 suction part, 414 support column, 415 pump, 416, 424 valve, 422 pressure source, 427 pressurized fluid, 432 voltage source, 434 switch, 436 electrostatic chuck, 500 pre-aligner, 601, 602, 603 correction part

Claims

[Claim 1] A substrate bonding apparatus for bonding a first substrate and a second substrate, A measuring unit for measuring information regarding the positional misalignment between the first substrate and the second substrate that occurs when the first substrate and the second substrate are bonded together, A substrate bonding apparatus having a correction unit that deforms at least one of the first substrate and the second substrate based on the information regarding the positional misalignment.

Images