WO2017155002A1 - Substrate bonding method - Google Patents

Abstract

A substrate bonding method comprises: a hydrophilization process step of performing a hydrophilization process for causing water or an OH-containing substance to become attached to a bonding face surface of each of substrates (301, 302); a substrate warping step of warping the substrate (301); an abutting step of abutting the bonding face of the substrate (301) and the bonding face of the substrate (302) against each other at center portions thereof; and a laminating step of reducing the distance between an outer peripheral portion of the substrate (301) and an outer peripheral portion of the substrate (302) with the center portions thereof abutted against each other so as to maintain a constant distance, and reducing the distance until the bonding face of the substrate (301) and the bonding face of the substrate (302) are positioned for lamination across the entire faces thereof. Before or after the abutting step, the distance between the substrates (301, 302) is measured and the distance between the outer peripheral portions of the substrates (301, 302) is reduced.

Description

Substrate bonding method

The present invention relates to a substrate bonding method.

In the field of electronics, mounting technology has been developed for bonding electronic components and substrates to each other, and bonding between substrates provided with electronic circuits and electronic wiring. An object to be bonded by such a mounting technique has an electrode electrically connected to an electronic circuit or the like on the bonding surface. The electrodes are joined together to establish electrical connection between the objects to be joined.

Electronic devices are always required to be smaller and lighter. Accordingly, circuit patterns such as electronic circuits have been increased in density and miniaturization. Thereby, the request | requirement which improves the positioning accuracy of the to-be-joined objects joined mutually has increased.

In order to meet this requirement, after the objects to be joined are brought into contact with each other, the positional deviation of both the objects to be joined is measured, the positional deviation is corrected, and the positions of both the objects to be joined are adjusted. A joining method for joining together is disclosed (for example, see Patent Document 1).

By the way, when flat substrates are bonded as objects to be bonded, the wafer has a larger bonding surface area than a chip or the like. For this reason, when flat joining surfaces of flat substrates are brought into contact with each other and joined, air may enter between the joining surfaces, resulting in voids and product defects.

Therefore, a technique is used in which, after aligning the substrates, the center of the wafer is pressed and bent toward the mating wafer to be bonded. In this method, the central portion is pressed while holding the outer peripheral portion of the wafer, and the bonding surface of the wafer is bent against the counterpart wafer by bending the central portion so that the central portion is convex toward the counterpart wafer. . Then, the bent central portion of the bent wafer hits the bonding surface of the mating wafer. Thereafter, the bent wafer is released. Then, the bent wafer is restored to the original flat plate shape, and bonded to the mating wafer and the entire bonding surface.

At this time, in the process of restoring the original flat plate shape, the bent wafer sequentially contacts the counterpart wafer from the convex central part toward the outer peripheral side, so the air between the wafers This prevents the air from entering between the bonding surfaces of the wafers.

JP 2011-66287 A

However, after the wafers are aligned as described above, the center portion of the wafer is pressed against the mating wafer to be bonded and bent, or the bent wafer is released and the wafer is released. While restoring the original flat shape, the wafer may be displaced.

The present invention has been made in view of the above reasons, and provides a substrate bonding method capable of preventing generation of voids between substrates and bonding with high positional accuracy when bonding substrates. That is.

In order to achieve the above object, a substrate bonding method according to the present invention includes:
A method of bonding a first substrate and a second substrate,
A hydrophilization treatment step of performing a hydrophilization treatment for attaching water or an OH-containing substance to the surfaces of the respective bonding surfaces of the first substrate and the second substrate;
Bending the substrate for bending the first substrate with respect to the outer peripheral portion of the bonding surface such that a central portion protrudes toward the second substrate;
A butting step of abutting the joint surface of the first substrate and the joint surface of the second substrate at the central portions;
In a state where the central portions are in contact with each other so as to maintain a constant distance, the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced, and the bonding surface of the first substrate A pasting step of laminating the joint surface of the second substrate over the entire surface,
Before or after the matching step, the distance between the first substrate and the second substrate is measured, and the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate Reduce the distance.

The substrate bonding method according to the present invention from another viewpoint is as follows:
A method of bonding a first substrate and a second substrate,
A hydrophilization treatment step of performing a hydrophilization treatment for attaching water or an OH-containing substance to the surfaces of the respective bonding surfaces of the first substrate and the second substrate;
Bending the substrate for bending the first substrate with respect to the outer peripheral portion of the bonding surface such that a central portion protrudes toward the second substrate;
A butting step of abutting the joint surface of the first substrate and the joint surface of the second substrate at the central portions;
In a state where the central portions are in contact with each other so as to maintain a constant distance, the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced, and the bonding surface of the first substrate A bonding step of bonding the bonding surface of the second substrate to the entire surface;
During or after the bonding step, the first substrate and the second substrate including a displacement amount corresponding to a warp amount with respect to an outer peripheral portion of a central portion of the first substrate and the second substrate temporarily bonded to each other. A positional deviation amount measuring step for measuring the positional deviation amount with respect to the substrate;
A position for correcting the relative position of the first substrate and the second substrate, the amount of warpage of the first substrate, and the amount of warpage of the second substrate so that the amount of positional deviation becomes small. A correction step.

According to the present invention, when the substrates are bonded to each other, it is possible to prevent generation of voids between the substrates and to bond with high positional accuracy.

It is a schematic front view which shows the schematic structure inside the board | substrate bonding apparatus which concerns on embodiment of this invention. It is a schematic schematic perspective view which shows the stage and head vicinity which concern on embodiment. It is a rough front sectional view showing the configuration of the stage holding the substrate according to the embodiment. It is a schematic sectional drawing of the protrusion mechanism which concerns on embodiment. It is a rough front sectional view showing the state where the substrate was bent by the projection mechanism provided in the stage according to the embodiment. It is a schematic front view which shows the structure of the holding mechanism provided in the stage which concerns on embodiment. It is a rough front sectional view showing a state where both substrates are bent by the protruding mechanism provided in the stage according to the embodiment. It is a rough front sectional view showing another example of the protruding mechanism according to the embodiment. It is a rough front sectional view showing the configuration of the stage and substrate heating means according to the embodiment. It is a schematic diagram showing two alignment marks attached to one substrate according to the embodiment. It is a schematic diagram showing two alignment marks attached to the other substrate according to the embodiment. It is a schematic diagram which shows the image obtained by image | photographing the alignment mark regarding both the board | substrates concerning embodiment. It is a schematic diagram showing a state where a set of marks according to the embodiment are displaced from each other. It is a flowchart which shows the board | substrate joining method which concerns on embodiment. It is a rough front sectional view showing a state where the central portion of the bent substrate according to the embodiment is abutted against the upper substrate. It is a figure explaining the center push joining method which extrudes the center part of a board | substrate from the top which concerns on embodiment. It is a figure explaining the center push joining method concerning an embodiment. It is a perspective view explaining the method of calibrating the parallelism and distance of the stage which concerns on embodiment in a micron unit. It is a side view explaining the method to calibrate the parallelism and distance of the stage which concerns on embodiment in a micron unit. It is a figure explaining the method of correct | amending the wafer thickness dispersion | variation which concerns on embodiment, and performing gap adjustment. It is a rough front sectional view showing the state where the substrates concerning an embodiment were piled up. It is a rough front sectional view showing the state where the substrates concerning an embodiment were piled up. It is a schematic sectional drawing which shows the state which made the center parts of two board | substrates contact in the bonding process which concerns on embodiment. It is a schematic sectional drawing which shows the state which joined two board | substrates temporarily in the bonding process which concerns on embodiment. It is a schematic sectional drawing which shows the state which hold | maintained the board | substrate in the alignment process which concerns on a modification. It is a schematic sectional drawing for demonstrating the method to measure the space | interval of two board | substrates in the alignment process which concerns on a modification. It is a schematic sectional drawing which shows a mode that the amount of curvature of each of the two board | substrates which concern on a modification is measured. It is a rough front sectional view showing a state where both substrates are bent by a protruding mechanism provided in a stage according to a modification. It is a schematic sectional drawing of the two board | substrates in the bonding process which concerns on a modification, Comprising: It is a figure which shows the state which shrunk | reduced the distance between two board | substrates after matching two board | substrates. It is a schematic sectional drawing of the two board | substrates in the bonding process which concerns on a modification, Comprising: It is a figure which shows the state which shortened the distance between two board | substrates further. It is a flowchart which shows the board | substrate joining method which concerns on a modification. It is a figure for demonstrating the method to measure the positional offset amount according to the curvature amount of the two board | substrates temporarily joined mutually based on the modification, and image | photographed the alignment mark regarding the two board | substrates temporarily joined mutually. FIG. It is a figure for demonstrating the method to measure the positional offset amount according to the curvature amount of the two board | substrates temporarily joined mutually concerning the modification, and is a schematic sectional drawing which shows the state of the two board | substrates temporarily joined mutually is there. It is a schematic sectional drawing which shows the state just before temporary joining of two board | substrates. It is a schematic sectional drawing which shows the state which temporarily joined two board | substrates. It is a schematic sectional drawing for demonstrating the setting method of the curvature amount of each board | substrate based on the positional offset amount according to the curvature quantity of the two board | substrates temporarily joined mutually. It is a schematic sectional drawing which shows the state just before temporary joining of two board | substrates. It is a schematic sectional drawing which shows the state which temporarily joined two board | substrates. It is a schematic sectional drawing for demonstrating the setting method of the curvature amount of each board | substrate based on the positional offset amount according to the curvature quantity of the two board | substrates temporarily joined mutually. It is a schematic front view which shows the structure of the holding mechanism provided in the stage which concerns on a modification. It is a schematic sectional drawing which shows the state which made the center parts of two board | substrates contact in the temporary joining process which concerns on a modification. It is a schematic sectional drawing which shows a mode that two board | substrates mutually detach | leave from each other in the board | substrate release process which concerns on a modification. It is a schematic sectional drawing which shows a mode that two board | substrates mutually left | separated in the board | substrate release process which concerns on a modification. It is a schematic sectional drawing which shows a mode that two board | substrates are mutually bonded in the bonding process which concerns on a modification. It is a schematic sectional drawing which shows the state which bonded together two board | substrates in the bonding process which concerns on a modification. It is a schematic sectional drawing which shows the state which mutually bonded two board | substrates in the relative position measurement process which concerns on a modification. It is a schematic sectional drawing which shows the state which mutually bonded two board | substrates in the relative position measurement process which concerns on another modification.

DETAILED DESCRIPTION Hereinafter, embodiments for carrying out a substrate bonding method and a substrate bonding apparatus according to the present invention will be described with reference to the accompanying drawings.

The substrate bonding method according to the present embodiment is a method of bonding a first substrate and a second substrate, and water or OH is formed on the surface of each bonding surface of the first substrate and the second substrate. A step of performing a hydrophilization treatment for adhering a contained substance, and bending the first substrate with respect to an outer peripheral portion of the bonding surface so that a central portion protrudes toward the second substrate, In the state of abutting the bonding surface of the second substrate and the bonding surface of the second substrate with each other at the center portion, and in a state where the center portions are butted so as to maintain a constant distance, A bonding step of reducing the distance between the outer peripheral portion and the outer peripheral portion of the second substrate, and reducing the distance to a position where the bonding surface of the first substrate and the bonding surface of the second substrate are bonded to each other; And in the bonding step, the bonding position Measured or detected, reduce the distance between the outer peripheral portion of the second substrate and the outer peripheral portion of the first substrate.

By adopting the configuration as described above, even when the substrate is separated from the stage at a marginal position during the bonding process, it is possible to perform the bonding on the entire surface without causing any displacement or distortion. In addition, by defining the position where the entire surfaces are bonded together as described above, it is possible to suppress the occurrence of a shift in the relative position between the substrates without causing excessive pressure. In addition, by measuring or detecting the position where it is pasted and determining the position at the last minute, the center displacement from both sides with a 10 μm gap, which was impossible in the past, has been limited to about 1 μm in the past. What was present could be accommodated within 0.1 μm. The data is shown in Experimental result 1. Usually, the flatness of the glass stage is about 5 μm, and by adjusting the parallelism to submicron and controlling the gap, it becomes possible to bring the gap closer to about 10 μm for the first time up and down without applying pressure. Further, it is preferable to perform bonding in a vacuum because it becomes easy to eliminate voids due to air entrainment even in a gap of 10 μm.

In the above bonding method, the first substrate and the second substrate are arranged with the bonding surfaces facing each other between the hydrophilization treatment step and the bonding step, and the first substrate Between the first substrate and the second substrate so that the amount of positional deviation between the first substrate and the second substrate is small. A step of adjusting the relative position.

Further, the above bonding method further includes a step of measuring a positional shift amount between the first substrate and the second substrate during or after the bonding step. By measuring the positional deviation during the bonding process, that is, before the bonding of the entire surface is completed, and separating the substrates, the bonding process or the relative position adjusting process can be repeated. For this reason, the precision of alignment of the relative positions between the substrates can be further increased.

When the measured amount of positional deviation exceeds the allowable error range, the outer peripheral portion of the first substrate and the second substrate are in contact with each other so that the central portions keep a constant distance. And the step of returning the deflection of the central portion of the first substrate, and the first substrate and the second substrate so that the positional deviation amount is small. Adjusting the relative position of the substrate and the second substrate, and the first substrate is centered with respect to the outer peripheral portion of the bonding surface until the amount of displacement is within an allowable error range. The process from the step of bending so that the portion protrudes toward the second substrate side to the step of adjusting the relative position between the first substrate and the second substrate is repeated.

FIG. 1 is a front view showing a schematic structure inside a substrate bonding apparatus 100 according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing the vicinity of the stage and the head. FIG. 3 is a front sectional view showing the configuration of the stage holding the substrate. FIG. 7 is a front sectional view showing another example of the protruding mechanism. In the following description, directions and the like are shown using an XYZ orthogonal coordinate system for convenience.

As shown in FIG. 1, the substrate bonding apparatus 100 includes a chamber 200, a substrate (second substrate) 301 that is an object to be bonded, and a substrate support unit 400 that supports the substrate (first substrate) 302 so as to face each other. , A position measuring means (positioning unit) 500 for measuring the relative positional relationship between the substrates 301 and 302, and a hydrophilic treatment means 600 for performing a surface activation process on the surfaces of the substrates 301 and 302 that are supported to face each other. And a controller (control unit) 700 that controls the operation of each unit of the substrate bonding apparatus 100. Examples of the substrates 301 and 302 include a glass substrate, an oxide substrate (for example, a silicon oxide (SiO ₂ ) substrate, an alumina substrate (Al ₂ O ₃ )), a nitride substrate (for example, silicon nitride (SiN), and aluminum nitride. (AlN)).

<Chamber>
The chamber 200 has a hollow box shape, and stages 401 and 402 of a substrate support means 400 described later are provided therein. The chamber 200 includes a vacuum pump 201 as a evacuation unit for evacuating the inside. The vacuum pump 201 is connected to the chamber 200 via the exhaust pipe 202. The exhaust pipe 202 is provided with an exhaust valve 203 that opens and closes the exhaust pipe 202.

In such a chamber 200, the exhaust pipe 202 is opened and the vacuum pump 201 is operated to discharge the gas in the chamber 200 to the outside through the exhaust pipe 202. As a result, the inside of the chamber 200 is depressurized and evacuated, and the atmosphere in the chamber 200 is brought into a vacuum or low pressure state. Further, the exhaust valve 203 can adjust the exhaust flow rate in the exhaust pipe 202 by changing the opening / closing amount thereof, and can adjust the target vacuum degree in the chamber 200.

<Distance measuring means>
Distance measuring means for measuring the distance between the stage (second substrate holding unit) 401 holding the substrates 301 and 302 and the stage (first substrate holding unit) 402 before the step of bending the central portion of the substrate 301 or 302. (Not shown). The distance measuring means is preferably a device that can measure the distance between stages without contacting the stage, such as a laser distance meter.

<Wafer thickness measuring means>
Prior to the step of bending the central portion of the substrate 301 or 302, a wafer thickness measuring means (not shown) for measuring the thickness of each of the substrates 301 and 302 is provided. The wafer thickness measuring means is preferably capable of measuring the thickness of the substrate without contacting the substrate, such as a laser displacement meter. In the present embodiment, the wafer thickness is measured at three locations with a laser from above and below at the aligner position. Alternatively, the required thickness may be calculated by measuring the circumference or the entire surface.

The distance between the substrates 301 and 302 can be calculated from the measurement results of the distance measuring means and the wafer thickness measuring means. Here, the distance between the substrates 301 and 302 is the distance between the bonding surfaces of the substrates 301 and 302, and the stage (second substrate holding unit) 401 and the stage (first substrate holding) measured by the measurement means described above. Part) 402, and can be calculated as a distance obtained by subtracting the thickness of each of the substrates 301 and 302 measured by the wafer thickness measuring means.

<Substrate support means>
The substrate support means 400 includes a stage (second substrate holding unit) 401, a stage (first substrate holding unit) 402 for supporting the substrates 301 and 302, stage driving mechanisms 403 and 404 for moving the respective stages, and a substrate. Substrate heating means 420 for heating.

Stages 401 and 402 are provided to face each other in the vertical direction (Z direction). The upper surface of the lower stage 401 is a support surface of the substrate 301. The lower surface of the upper stage 402 is a support surface of the substrate 302. The support surfaces of these stages 401 and 402 are arranged in parallel to each other.

The stages 401 and 402 may have a holding mechanism such as a mechanical chuck, an electrostatic chuck, or a vacuum chuck on each support surface. This holding mechanism can switch between a fixed state of the substrates 301 and 302 to the support surface and an open state from the fixed state of the substrates 301 and 302 to the support surface.

The lower stage 401 includes a stage drive mechanism 403. The stage drive mechanism 403 moves the lower stage 401 in the XYθ direction within a horizontal plane orthogonal to the vertical direction (Z direction) in which the stage 401 and the stage 402 face each other.

The upper stage 402 includes a Z-direction lifting drive mechanism 406 and a Z-axis rotation drive mechanism 407 as the stage drive mechanism 404. The stage drive mechanism 404 can further include an XY direction drive mechanism 405.

The Z-direction lifting / lowering drive mechanism 406 moves the stage 402 in the Z direction, thereby moving the stages 401 and 402 closer to or away from each other along the Z direction. Further, the Z-direction lifting drive mechanism 406 brings the stages 401 and 402 close to each other to bring the bonded surfaces of the held substrates 301 and 302 into contact with each other, and further pressurizes the substrates 301 and 302 that are in contact with each other. be able to.

The Z direction elevating drive mechanism 406 is provided with a pressure sensor 408 for measuring a force related to the Z axis. The pressure sensor 408 detects the pressure acting on the bonding surfaces of the substrates 301 and 302 that are pressed against each other by the Z-direction lift drive mechanism 406. For example, a load cell can be used as the pressure sensor 408.

In a state where the central portions of the substrates 301 and 302 are abutted with each other by a pressure that maintains the non-bonded state by the Z-direction lifting drive mechanism 406, or in a state where the distance between the central portion of the substrate 301 and the central portion of the substrate 302 is maintained The distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 can be reduced, and the bonding surface of the substrate 301 and the bonding surface of the substrate 302 can be moved so as to abut on the entire bonding surface.

The XY direction drive mechanism 405 can slide the stage 402 in the XY direction orthogonal to the Z direction where the stage 401 and the stage 402 face each other.

As shown in FIGS. 1 and 2, between the XY direction drive mechanism 405 and the stage 402, a plurality of, for example, three projecting mechanisms 412 are provided in the vicinity of the outer periphery of the stage 402 at intervals in the circumferential direction. It has been. The protruding mechanisms 412 are independently extended and contracted in the Z direction. By these protrusion mechanisms 412, the distribution of force or pressure acting on the bonding surfaces of the substrates 301 and 302 is finely or accurately adjusted.

Further, a stage pressure sensor 411 is provided between each protrusion mechanism 412 and the XY direction drive mechanism 405. The operation of the protruding mechanism 412 is controlled by a control unit (not shown) according to the distribution of force or pressure acting on the bonding surfaces of the substrates 301 and 302 measured by the plurality of stage pressure sensors 411. The stage pressure sensor 411 and the protrusion mechanism 412 further finely adjust the distribution of pressure acting on the substrates 301 and 302 that are pressed against each other by the Z-direction lift drive mechanism 406, and extend over the joint surface. It can be a uniform or predetermined distribution.

In one embodiment of the present invention, the speed at which the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 is reduced based on the pressure generated on the bonding surface of the substrate 301 and the bonding surface of the substrate 302, that is, the Z-direction lift drive mechanism It is preferable to adjust the operation speed of 406. With such a structure, the pressure generated on the bonding surface of the substrate 301 and the bonding surface of the substrate 302 can be maintained at a constant force.

Alternatively, the operation of the Z-direction lifting drive mechanism 406 may be stopped based on the pressure generated on the bonding surface of the substrate 301 and the bonding surface of the substrate 302. When the pressure generated on the bonding surface of the substrate 301 and the bonding surface of the substrate 302 exceeds a certain value, for example, when the direction in which the substrate is pressed against the counterpart substrate is positive, the pressure generated on the bonding surface of the substrate is When the value is greatly negative, it is considered that a force is working to reduce the distance between the substrates. By reducing the distance between the substrates in such a state, the substrates may be deformed by a force generated in the X or Y direction. When such deformation occurs, positional displacement between the bonded substrates occurs.

By maintaining the pressure generated on the bonding surface of the substrate 301 and the bonding surface of the substrate 302 at a constant force and stopping the operation of the Z-direction lifting drive mechanism 406 when this pressure exceeds a certain value, time passes. Then, the force to reduce the distance between the substrates is alleviated and returns to a certain value or less. When the pressure generated on the bonding surface of the substrates returns to a certain value or less, the Z-direction lift drive mechanism 406 can be re-driven again.

Moreover, in one embodiment of the present invention, when the direction in which the substrate is pressed against the counterpart substrate is positive, the bonding surface of the substrate is maintained so that the pressure generated on the bonding surface of the substrate does not become a negative value. It is more preferable to maintain the pressure generated in As an example, when the lower limit value of the pressure generated on the bonding surface of the substrate is set to −100 N, the operation speed is controlled or the operation is temporarily stopped when the detected pressure becomes −150 N or less. . This can be applied both when the distance between the substrates is reduced and when the distance is removed.

In one embodiment of the present invention, the pressure generated on the bonding surface of the substrates can be detected by a plurality of stage pressure sensors 411. Thereby, even if the substrate 301 or 302 has thickness variation or distortion, deformation due to pressure generated between the substrates can be suppressed.

Further, even when the Z-direction lifting / lowering drive mechanism 406 is raised to increase the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302, the pressure generated on the bonding surface of the substrate is maintained so as not to exceed a certain value. You may do it.

The Z axis rotation drive mechanism 407 can rotate the stage 402 around the Z axis. The rotational drive mechanism 407 can control the rotational position θ around the Z axis with respect to the stage 401 with respect to the stage 401, thereby controlling the relative positions of both substrates 301 and 302 in the rotational direction.

Prior to releasing the bent first substrate, the control unit evacuates the atmosphere around the first substrate and the second substrate in the chamber so that the air can be bonded without voids. It becomes possible.

In the field where the microelectrode called hybrid bonding and the surrounding insulating layer are bonded at the same time, the microelectrode portion made of Cu is subjected to CMP polishing in a dented state, and the insulating layer is first bonded at a low temperature of about 150 ° C. Then, there is a method in which the Cu electrodes are expanded by heating to about 350 ° C. to fill the gaps and diffusely bond Cu to each other. When joining in the atmosphere in this method, the gap between the Cu electrodes is filled with the atmosphere, and the surface of the Cu electrode is oxidized in the heating and expansion process, which is not preferable for joining. In addition, the air in the gap remains void as it has nowhere to go. In addition to SiO _{2 which} is a constituent material of the substrate, when a Cu electrode is included in the bonding surface, it is more preferable to apply heat and pressure in the bonding step.

In the bonding apparatus according to the present embodiment, the gap is vacuumed by bonding in vacuum, so that oxidation can be suppressed and generation of voids can also be suppressed. As for the timing of evacuation, it is possible to correct misalignment because there are many water molecules in the contact part by securing the atmospheric environment in the state where the center part is in contact, but it is a short time within a few minutes In addition, if the degree of vacuum is about several hundred Pa, it is possible to leave water molecules at the interface to some extent even if vacuuming is performed from the beginning.

Also, by vacuuming immediately before contacting the central portion, the entire surface can be secured in a vacuum atmosphere while interposing water molecules. If position correction after contact is not required, a vacuum may be drawn from the beginning.

In addition, the alignment process between the first substrate and the second substrate may be performed before releasing the bent substrate or after evacuation. The time required for alignment is several seconds to several tens of seconds, and does not affect the bonding of the substrates.

In one embodiment of the present invention, a stage 402 (or stage 401) not holding a substrate while holding only one of the substrates 301 (or substrate 302) before the step of bending the central portion of the substrate. And a distance measuring means (not shown) for measuring the distance between the substrate and the held substrate.

The distance measuring means is preferably a laser distance meter provided in the stage 402 (or stage 401), for example, and can measure the distance from the opposing stage or the upper surface of the substrate to the stage without contacting the opposing stage or substrate. . The distance between the substrates 301 and 302 can be calculated from the measurement results of the distance measuring means and the wafer thickness measuring means. For example, it is possible to obtain the inter-stage distance from the difference between the reflected light on the upper surface of the lower glass stage and the reflected light on the lower surface of the upper glass stage by introducing laser light from the upper part of the head side upper glass stage. When the wafer is on the lower stage, the distance between the lower surface of the upper glass stage and the upper surface of the lower wafer can be obtained.

In one embodiment of the present invention, distance measuring means (not shown) is provided for measuring the distance between the bonding surfaces of the substrate 301 and the substrate 302 in a state where the substrate 301 and the substrate 302 are held on the stages 401 and 402. Also good. Specifically, a mode in which a distance measuring unit capable of measuring the distance between the bonding surfaces of the substrate 301 and the substrate 302 is inserted between the substrates to measure the distance between the substrates can be mentioned.

<Projecting mechanism>
As shown in FIG. 3, in the upper stage 402, a protruding mechanism 430 that can be projected and retracted toward the lower stage 401 side is built in the central portion of the support surface that supports the substrate 302. The protruding mechanism 430 can employ a cylinder structure or an electromagnetic mechanism. It is preferable that the protrusion mechanism 430 has at least a force that bends the substrate 302 and has a function of moving in a direction opposite to the protruding direction when receiving a force in a direction opposite to the protruding direction for a certain amount.

As shown in FIG. 4, the protruding mechanism 430 includes a pressing member 434 that presses the substrate 302, a voice coil motor 433, and a displacement sensor 435. The voice coil motor 433 includes a bottomed cylindrical coil bobbin 4331, a coil 4332 wound around the coil bobbin 4331, a magnet 4333 disposed to face the coil 4332, and a bottomed cylindrical part covering the outside of the coil 4332. And a yoke 4334 configured from a bottom portion of the bottomed cylindrical portion and a protruding portion fitted inside the coil 4332. The pressing member 434 is fixed to the bottom of the coil bobbin 4331 of the voice coil motor 433. A yoke 4334 of the voice coil motor 433 is fixed to the stage main body 4021. In the voice coil motor 433, when a current flows through the coil 4332, the coil bobbin 4331 moves along the cylinder axis direction. As a result, the pressing member 434 fixed to the coil bobbin 4331 moves in a direction protruding from the stage 402 or a direction immersing in the stage 402. Then, by controlling the magnitude of the current flowing through the coil 4332, the pressure applied to the substrate 302 by the pressing member 434 fixed to the coil bobbin 4331 can be controlled. Further, the pressing member 434 includes a protruding portion 4341 that protrudes from the stage main body 4021 to the outside, and a flat base portion 4342 that is formed integrally with the protruding portion 4341. And the displacement sensor 435 is comprised, for example from an eddy current type displacement sensor, and measures the distance LH between the detection part 435a and the base part 4342 of the press member 434. FIG. The substrate bonding apparatus 100 can execute position control of the pressing member 434 fixed to the coil bobbin 4331 based on the distance LH measured by the displacement sensor 435. As described above, since the protruding mechanism 430 uses the voice coil motor 433, pressure control when the pressing member 434 presses the substrate 302 and position control of the pressing member 434 are possible. For example, when the substrate bonding apparatus 100 performs pressure control while pressing the substrate 302 with the pressing member 434, if the position of the pressing member 434 is out of a preset range, the substrate bonding apparatus 100 controls the pressing member 434. By switching to position control, the pressing member 434 can be returned to a preset range. As described above, the substrate bonding apparatus 100 can combine pressure control and position control of the pressing member 434.

In addition, as a protrusion mechanism, it may have a cylinder structure, for example, and can change a pressurizing force by changing the air pressure supplied in a cylinder. Moreover, as a protrusion mechanism, it is an electromagnetic coil type | mold and can change a applied pressure by changing the electric current value of the electric current which flows into a coil.

The projecting mechanism is pushed down by bringing the substrates closer to each other by the vertical movement axis between the substrates, for example, the Z axis in this embodiment, to bring the distance between each substrate of the head or stage from the bent state. , And the contact area can be increased from the center to the outer periphery, following the other flat substrate.

Also, the speed of wetting and spreading can be controlled by numerically controlling the distance between the substrates. Depending on the surface activation situation, the wetting speed is different, and the conventional method of inserting the claw between the wafers and pulling it out and dropping it naturally causes voids, so speed control is an effective method.

When both substrates are bent, if one side is an actuator that can be numerically controlled, for example, a piezo actuator, the distance from the bottom surface of each substrate to the center portion can be expanded and contracted according to the Z-axis movement of the head. The contact area can be increased to the outer peripheral portion by moving the outer peripheral portion closer while maintaining the same upper and lower sides.

In this case, if only one side is bent, the alignment mark position of the substrate on one side is also shifted inward, resulting in poor alignment accuracy and distortion during joining. By bending from both directions, the alignment mark position can be brought to the same position, and bonding can be performed without causing distortion at the time of joining, which is an effective method compared to a conventional one-side protruding mechanism.

For example, the amount of protrusion that required 20 μm on one side can be accommodated at 10 μm on both sides, resulting in less distortion. In particular, this method is particularly effective in the field of simultaneously bonding a microelectrode called a hybrid bonding that requires submicron accuracy and a peripheral insulating layer, for example, a CMOS image sensor, a memory, an arithmetic element, and a MEMS.

In addition, when the center part is contacted, both end marks of the substrate are read with an image processing device, and the amount of displacement is corrected and then moved for correction.If water molecules exist at the interface between the two substrates and the applied pressure is small, Although the correction movement can be performed in the contact state, when the contact area is large, the protrusion mechanism may be pulled back once to provide a correction movement with a gap between both substrates. Further, it is possible to provide a gap by moving the Z-axis without changing the protruding mechanism. Moreover, a clearance gap can also be provided using both.

FIG. 5 is a front sectional view showing a state in which the substrate 302 is bent by the protruding mechanism 430 provided in the stage 402. As shown in FIG. 5, when the protrusion mechanism 430 is protruded from the stage 402, the outer peripheral portion 302s of the substrate 302 receives a downward force due to its own weight so that the central portion 302c of the substrate 302 protrudes upward. Bend. Note that “protruding mechanism 430 protrudes from stage 402” means that the pressing member 434 of the protruding mechanism 430 protrudes from the stage 402 in detail. Hereinafter, the same applies to the present specification. When the pressing by the protruding mechanism 430 is released, or when the substrate 302 is abutted against the opposing substrate 301 and receives a force exceeding a certain level, the substrate 302 is restored to the original flat plate shape.

The top portion 430a that contacts the substrate of the protruding mechanism 430 may have a curved shape as shown in FIG. Thereby, a board | substrate can be bent, without applying a local force to a board | substrate. Moreover, this can also suppress the displacement of the substrate.

In one embodiment of the present invention, when the distance between the outer peripheral portion 301 s of the substrate 301 and the outer peripheral portion 302 s of the substrate 302 is reduced, the bonding of the central portion 301 c of the substrate 301 is performed separately from the method for defining the bonding position as described above. It is preferable to reduce the distance between the outer peripheral portion 301 s of the substrate 301 and the outer peripheral portion 302 s of the substrate 302 by the protruding distance of the surface with respect to the bonding surface of the outer peripheral portion 301 s of the substrate 301. In this embodiment, preferably, the distance between the outer peripheral portion 301 s of the substrate 301 and the outer peripheral portion 302 s of the substrate 302 is reduced by a distance equivalent to the protruding distance of the protruding mechanism 430. For example, the bonding position can be determined from the pushing amount of the protruding mechanism 430 measured by the above-described displacement sensor 435. For example, the detection value of the displacement sensor 435 at the abutting position is stored, and the protrusion amount can be calculated from the difference from the detection value of the displacement sensor 435 when protruding. In addition, when the vertical center push is performed, the vertical protrusion amount may be added. There are a method in which the amount of lowering Z is lowered by the amount of protrusion, and a method in which the detected value of the displacement sensor 435 is lowered until the detected value of the displacement sensor 435 at the pre-stored butt position is reached. A method of determining the abutting position with a value obtained by adding up and down in consideration of the vertical variation is preferable. Further, a correction amount may be added as appropriate.

<Holding mechanism>
The stages 401 and 402 may have a holding mechanism 440 such as a mechanical chuck, an electrostatic chuck, or a vacuum chuck on each support surface. This holding mechanism can switch between a fixed state of the substrates 301 and 302 to the support surface and an open state from the fixed state of the substrates 301 and 302 to the support surface.

The holding mechanism may be divided into a plurality of regions on the surfaces of the stages 401 and 402 as shown in FIG. For example, in the example of FIG. 6, two holding mechanisms, an outer holding mechanism 440a and an inner holding mechanism 440b, are provided. The outer holding mechanism 440a and the inner holding mechanism 440b can be controlled independently, and the inner holding mechanism 440b is opened while the outer holding mechanism 440a holds the outer peripheral portion of the substrate, and the Z-axis is formed in the central portion of the substrate. It is possible to avoid receiving force in the direction.

When a plurality of holding mechanisms 440 are provided, for example, holding mechanisms having different principles and functions, such as an electrostatic chuck and a vacuum chuck, may be used in combination. For example, electrostatic chuck electrodes and vacuum chuck suction grooves may be provided alternately in the radial direction of the stage.

In addition to the above configuration, a mechanism similar to the protruding mechanism 430 may be provided on the lower stage 401 side. As shown in FIG. 7, by adopting a configuration in which the substrates 301 and 302 are bent by both the stages 401 and 402, the amount of bending of the substrate is reduced, and the substrate can be aligned with less error.

When the lower substrate 301 is bent, it is preferable to hold only the outer peripheral portion 301 s of the substrate 301. In this case, it is preferable that only the outer peripheral portion 301s of the substrate 301 is held by the outer holding mechanism 440a because the substrate bends to a desired shape even if the force of pressing the substrate by the protruding mechanism 430 is weak.

In the above bonding apparatus, when the holding mechanism 440 is a vacuum suction method, the suction groove provided on the stage may be separated by the location of the substrate. For example, the suction groove for holding the peripheral portion of the substrate and the suction groove for holding the central portion of the substrate may be separated and each may operate separately. Thereby, only the outer peripheral part of a board | substrate can be hold | maintained.

Also, the central part is first vacuum-adsorbed, and when it bends, it breaks down to the atmospheric pressure. The substrate can be easily peeled off by releasing pressurized air for a few seconds. In addition, when the substrate is difficult to peel off at the mirror surface, it is possible to make it easy to peel off while maintaining the height accuracy by intentionally roughening the holding portion contact surface.

In addition, the bonded substrate assembly may have variations in warpage and thickness. However, the entire surface of the lower stage 401 is again vacuum-sucked to reduce warpage and thickness variations in the substrate assembly. be able to.

In the above bonding apparatus, when the holding mechanism 440 is of the electrostatic chuck type, the holding mechanism is divided into a plurality of regions on the surfaces of the stages 401 and 402 as shown in an example in FIG. May be. For example, in the example of FIG. 6, two different patterns that can be individually controlled are provided, that is, the outer holding mechanism 440a and the inner holding mechanism 440b.

The outer holding mechanism 440a and the inner holding mechanism 440b can be controlled independently, and the inner holding mechanism 440b is opened while the outer holding mechanism 440a holds the outer peripheral portion of the substrate, and the Z-axis is formed in the central portion of the substrate. It is possible to avoid receiving force in the direction. When the central portion is bent, the vacuum suction groove in the central portion is used together to break the vacuum to atmospheric pressure. The substrate can be easily peeled off by releasing pressurized air for a few seconds.

Further, the holding mechanism may be divided into three, and one or more grooves may be inserted between the central portion and the outer peripheral portion to provide an air release layer. As a result, both the leaks are absorbed by the air release layer between the central part and the central part even when the central part releases pressurized air while maintaining the vacuum at the outer peripheral part. Even if the holding is peeled off or air is released, it is possible to prevent the central portion from being bent due to being sucked by the outer peripheral portion, which is effective. Further, the adsorbing part and the atmosphere releasing part are not limited to the grooves, and may be configured to support a plurality of points in the plane.

Further, as shown in FIG. 8, in the upper stage 402, a support plate that supports the substrate 302 may be provided with a pressing plate 431 having a thin plate shape and flexibility. The pressing plate 431 may have a holding mechanism (not shown) such as a vacuum suction method, a mechanical chuck, or an electrostatic chuck on a support surface that supports the substrate 302.

As shown in FIG. 8, when the protrusion mechanism 430 is protruded, the pressing plate 431 is elastically deformed, and the center portion 431c is bent so as to protrude downward. In this way, the pressing plate 431 is bent so as to protrude downward, whereby the central portion 302c of the substrate 302 on which the outer peripheral portion 302s is held by the holding mechanism (not shown) is directed toward the lower stage 401. Pressed. Then, the substrate 302 is elastically deformed along the pressing plate 431, and is bent so that the central portion 302c is convex downward with respect to the outer peripheral portion 302s. At this time, when the pressing plate 431 is bent, the entire substrate 302 is pressed and bent, so that the substrate 302 can be prevented from being distorted. When the pressing by the protruding mechanism 430 is released, the substrate 302 is restored to the original flat shape.

<Substrate heating means>
As shown in FIG. 1, the substrate heating means 420 includes heaters 421 and 422 built in stages 401 and 402. The heaters 421 and 422 are configured to generate Joule heat with, for example, an electric heater. The heaters 421 and 422 conduct heat through the stages 401 and 402 to heat the substrates 301 and 302 supported by the stages 401 and 402. By controlling the amount of heat generated by the heaters 421 and 422, the temperatures of the substrates 301 and 302 and their bonding surfaces can be adjusted. Stages 401 and 402 and heaters 421 and 422 may be formed of separate members. For example, the stages 401 and 402 including the holding mechanism 440 may be overlapped with the heaters 421 and 422 including the heater wiring. An example is shown in FIG.

It can also be joined as it is by heating with a heater of a joining device, but it can also be joined by taking it out in a bonded state and annealing it at 150 ° C. for several hours in a batch furnace or hot plate in a free state without pressure. .

<Position measuring means>
The position measuring unit 500 measures the relative positional relationship between the substrates 301 and 302. The position measuring means 500 includes a window 503 formed in the chamber 200, a light source (not shown), a plurality of cameras 501 and 502, and mirrors 504 and 505. Light emitted from a light source (not shown) passes through mirrors 504 and 505 and a window 503 and strikes portions (not shown) provided with marks on the substrates 301 and 302. The cameras 501 and 502 capture an image of reflected light from a portion (not shown) provided with marks on the substrates 301 and 302 through a window 503 and mirrors 504 and 505.

In FIG. 1, the cameras 501 and 502 each have a coaxial illumination system. The light source may be provided on the upper side of the stage 401 or may be provided so as to emit light from the cameras 501 and 502 side so as to travel along the optical axis. In addition, as the light of each coaxial illumination system of the cameras 501 and 502, a wavelength region (for example, the substrate can be made of silicon) that passes through portions where the marks are provided on the substrates 301 and 302 and portions where the light should pass such as both stages. If it is, infrared light) is used.

As a position measuring means for measuring the amount of displacement between the substrates 301 and 302, infrared transmission recognition is performed with the bonding surface of the substrate 301 and the bonding surface of the substrate 302 maintained at a distance that maintains the non-bonded state between the entire surfaces. It can be carried out. By performing position measurement from one direction of the stages 401 and 402 with one infrared transmission recognition camera, there is an advantage that no error occurs between the cameras compared to the case of using a plurality of cameras.

As described above, the relative positions of the substrates arranged opposite to each other may be measured by the cameras provided on the stages 401 and 402 side.

<Board alignment>
The substrate bonding apparatus 100 can measure and align the relative positions of the substrates 301 and 302 using the position measuring means 500, the driving mechanisms 403 to 407, and the controller 700 connected thereto.

The locations where light for measurement passes are defined on the substrates 301 and 302, and a mark is attached here to reflect, block or refract part of the passing light. When the cameras 501 and 502 receive the passing light, the alignment mark appears dark in the captured bright field image. Alternatively, when the reflected light from the alignment mark is received, the mark appears bright in a dark image. Preferably, a plurality of alignment marks are provided on the substrate, for example, at two opposite corners of the substrate. Thereby, the absolute position of the substrate 301 or 302 can be specified from the positions of the plurality of alignment marks.

Preferably, corresponding alignment marks are attached to corresponding portions of the substrates 301 and 302, for example, positions overlapping in the Z direction during bonding. Both alignment marks on the substrates 301 and 302 are observed within the same field of view, and the relative displacement amounts in the X and Y directions are measured. By measuring the relative displacement amounts in the X direction and the Y direction at a plurality of locations, the relative displacements (ΔX, ΔY, Δθ) of the substrates 301 and 302 in the X direction, Y direction, and θ direction are calculated. Can do.

It should be noted that the measurement operation of the positional deviation amount in the position measuring means 500 can be executed when the substrates 301 and 302 are in a non-contact state or a contact state.

<Measurement of relative position of substrate using marks>
As shown in FIG. 10, the substrate 301 is provided with two alignment marks (first alignment marks) MK1a and MK1b for alignment. Further, as shown in FIG. 11, the substrate 302 is also provided with two alignment marks (second alignment marks) MK2a and MK2b for alignment. Images obtained by photographing the alignment marks MK1a, MK1b, MK2a, and MK2b relating to both the substrates 301 and 302 are as shown in FIG. 12, for example.

The position measuring means 500 uses both images (image data) GA relating to transmitted light and reflected light of illumination light emitted from the respective coaxial illumination systems of the cameras 501 and 502 in a state where both the substrates 301 and 302 face each other. The positions of the substrates 301 and 302 can also be recognized. In other words, the positional deviation measurement for the alignment operation (fine alignment operation) of both the substrates 301 and 302 is performed by the cameras 501 and 502 with two sets of alignment marks (MK1a and MK2a) attached to both the substrates 301 and 302. ) And (MK1b, MK2b) are simultaneously recognized.

The position measuring means 500 acquires an image GAa including alignment marks MK1a and MK2a and an image GAb including alignment marks MK1b and MK2b as shown in FIG. 12, and attaches them to both substrates 301 and 302 based on the images GAa and GAb. The position of each set of marks (MK1a, MK2a), (MK1b, MK2b) is recognized. Based on the relative positions of the recognized marks (MK1a, MK2a) and (MK1b, MK2b), the controller 700 detects the amount of misalignment between the marks (MK1a, MK2a) and (MK1b, MK2b) as shown in FIG. Δxa, Δya) can be obtained.

FIG. 12 shows a state in which each set of marks (MK1a, MK2a), (MK1b, MK2b) is in a desired position with their centers overlapping each other, and FIG. 13 shows a set of marks (MK1a, MK2a). ) Shows a state of being deviated from the desired position.

As shown in FIG. 13, each image GAa, GAb (image GAa is shown in FIG. 13) is positioned for each set of marks based on the geometric relationship of the marks on the substrates 301, 302. Deviation amounts (Δxa, Δya) and (Δxb, Δyb) are obtained.

<Calculation of correction movement amount and movement operation>
The controller 700 detects X from the desired positions of the substrates 301 and 302 based on the positional deviation amounts (Δxa, Δya) and (Δxb, Δyb) of the two sets of marks (MK1a, MK2a) and (MK1b, MK2b). A relative deviation amount ΔD (specifically, Δx, Δy, Δθ) in the direction, the Y direction, and the θ direction is calculated. The relative deviation amount ΔD corresponds to the correction movement amount by the subsequent correction movement.

The controller 700 finally adjusts the substrates 301 and 302 by a correction amount −ΔD (−Δx, −Δy, −Δθ) corresponding to the relative deviation amount ΔD (Δx, Δy, Δθ) between the substrates 301 and 302. The path of the correction movement that moves is calculated. Then, the controller 700 instructs the drive mechanisms 403 to 407 of the stages 401 and 402 to move both the substrates 301 and 302 according to the calculated correction path.

The correction movement is performed so that the relative deviation amount ΔD is zero or reduced. In the case of the substrate bonding apparatus 100 shown in FIG. 1, stage driving is performed so that the stage 402 that supports the substrate 302 finally moves by a correction amount (−ΔD) with respect to the stage 401 that supports the substrate 301. The mechanisms 403 and 404 are controlled. The stage driving mechanisms 403 and 404 drive the two translational directions (X direction and Y direction) and the rotational direction (θ direction) and the stage 402 in accordance with an instruction from the controller 700. The relative displacement is made, and the positional deviation amount ΔD is corrected.

The correction movement is considered to be performed in a state where the bonding surfaces of the substrates are separated from each other and in a state where they are in contact with each other. Each correction movement will be described below.

In this way, the positional deviation amount ΔD (specifically, Δx, Δy, Δθ) in the plane (horizontal plane) perpendicular to the vertical direction (Z direction) is measured, and an alignment operation (correction is performed for the positional deviation amount ΔD). Fine alignment operation) is executed.

In addition, although the case where two images GAa and GAb are captured and acquired in parallel (substantially simultaneously) using two cameras 501 and 502 is illustrated here, the present invention is not limited to this. For example, the images GAa and GAb may be sequentially captured and acquired by moving one camera in the X direction and / or the Y direction. Moreover, although each set of marks was imaged simultaneously on the same optical axis, the present invention is not limited to this. For example, when the substrates are at different positions in the translational direction (X direction and Y direction), two sets (a total of four) cameras arranged for the respective substrate positions may be used. If the positional relationship of the optical axes of the cameras is known, each of the corresponding marks (MK1a, MK2a) is imaged by each camera and then combined to obtain a substantially joined position in the translation direction. It can be moved and positioned.

<Hydrophilic treatment means>
The substrate bonding apparatus 100 includes hydrophilic treatment means 600. The hydrophilic treatment means 600 of the substrate bonding apparatus 100 shown in FIG. 1 includes an activation processing unit 610 that activates the bonding surfaces of the substrates 301 and 302, and a hydrophilic treatment that hydrophilizes the activated bonding surfaces of the substrates 301 and 302. And a processing unit 620.

As the activation processing unit 610, for example, a particle beam source or a plasma source can be employed. The activation processing unit 610 removes the surface layer by causing a phenomenon (sputtering phenomenon) in which particles having a predetermined kinetic energy collide with each other in a vacuum to physically blow off the material forming the bonding surface. be able to. In the surface activation treatment, not only the surface layer is removed to expose the nascent surface of the substance to be bonded, but also the crystal structure near the exposed nascent surface is collided with particles having a predetermined kinetic energy. It is thought that there is also an effect of disturbing and amorphizing. Since the amorphized new surface has a higher surface area at the atomic level and a higher surface energy, it is considered that the number of hydroxyl groups (OH groups) per unit surface area to be bonded in the subsequent hydrophilization treatment is increased. On the other hand, in the case of chemically hydrophilizing after the surface impurity removal step by conventional wet processing, there is no physical change of the nascent surface due to collision of particles having a predetermined kinetic energy. It is considered that the hydrophilization treatment following the surface activation treatment according to the bonding method of the invention is fundamentally different from the conventional hydrophilization treatment in this respect. In addition, atoms in the vicinity of the nascent new surface that are disordered due to the crystal structure are easily diffused with relatively low thermal energy during the heat treatment during the main bonding, realizing a main bonding process at a relatively low temperature. I think it can be done.

As the particles used for the surface activation treatment, for example, a rare gas or an inert gas such as neon (Ne), argon (Ar), krypton (Kr), or xenon (Xe) can be used. Since these rare gases have a relatively large mass, it is considered that a sputtering phenomenon can be efficiently generated and the crystal structure of the nascent surface can be disturbed.

As the particles used for the surface activation treatment, oxygen ions, atoms, molecules, and the like may be employed. By performing the surface activation treatment using oxygen ions or the like, it is possible to cover the nascent surface with an oxide thin film after removing the surface layer. The oxide thin film on the nascent surface is believed to enhance the efficiency of hydroxyl (OH) group bonding or water attachment in subsequent hydrophilization treatments. In addition, it is considered that the oxide thin film formed on the nascent surface is relatively easily decomposed during the heat treatment in the main bonding.

It is preferable that the kinetic energy of the particles colliding with the surface-activated joint surface is 1 eV (electron volts) to 2 keV. It is considered that the above kinetic energy efficiently causes a sputtering phenomenon in the surface layer. A desired value of kinetic energy can also be set from the above kinetic energy range according to the thickness of the surface layer to be removed, the properties such as the material, the material of the new surface, and the like.

A predetermined kinetic energy can be given to the particles that collide with the surface-activated joint surface by accelerating the particles toward the joint surface.

Also, a predetermined kinetic energy can be given to the particles using a plasma generator. By applying an alternating voltage to the bonding surface of the substrate, a plasma containing particles is generated around the bonding surface, and the cations of the ionized particles in the plasma are accelerated toward the bonding surface by the voltage. Thus, given kinetic energy is given. Since the plasma can be generated in an atmosphere with a low degree of vacuum of about several pascals (Pa), the vacuum system can be simplified and the steps such as evacuation can be shortened.

The particle beam source operates in a relatively high vacuum, such as 1 × 10 ⁻² Pa (pascal) or 1 × 10 ⁻⁵ Pa or less, so unnecessary oxidation or renewal of the regenerated surface after the surface activation treatment is performed. Impurities can be prevented from adhering to the surface. Furthermore, since the particle beam source can apply a relatively high acceleration voltage, high kinetic energy can be imparted to the particles. Therefore, it is considered that the removal of the surface layer and the amorphization of the new surface can be performed efficiently.

For example, the plasma generator operates at 100 W and generates plasma of nitrogen (N ₂ ), oxygen (O ₂ ), and argon (Ar) as a hydrophilic treatment, and this plasma is applied to the bonding surface for about 30 seconds. If used to irradiate, treatment for hydrophilization can be performed. In addition, the plasma generator may be installed separately from the bonding apparatus so as to connect in the vacuum or handle the atmosphere once.

Neutral atoms or ions can also be used for the particles used for surface activation. In this case, a predetermined kinetic energy can be given to the particles using a particle beam source such as a neutral atom beam source or an ion beam source (ion gun) disposed at a position separated from the bonding surface. The particles to which a predetermined kinetic energy is applied are emitted from the particle beam source toward the bonding surface of the substrate. Further, nitrogen (N ₂ ), oxygen (O ₂ ), argon (Ar), or the like may be used as a reaction gas.

As the neutral atom beam source, a fast atom beam source (FAB, Fast Atom Beam) can be used. Fast atom beam sources (FABs) typically generate a plasma of gas, apply an electric field to the plasma, extract the cations of particles ionized from the plasma, and pass them through an electron cloud. It has the composition which becomes. In this case, for example, when argon (Ar) is used as the rare gas, the power supplied to the fast atom beam source (FAB) may be set to 1.5 kV (kilovolt), 15 mA (milliampere), or 0.1 W You may set to the value between (watt) and 500W (watt). For example, when a fast atom beam source (FAB) is operated from 100 W (watts) to 200 W (watts) and irradiated with a fast atom beam of argon (Ar) for about 2 minutes, the oxide, contaminants, etc. (surface) Layer) can be removed to expose the nascent surface.

The ion beam source (IG) may be used to operate at 110 V, 3 A, for example, to accelerate argon (Ar) and irradiate the bonding surface for about 600 seconds.

In the present invention, the particles used for surface activation may be neutral atoms or ions, may be radical species, and may be a particle group in which these are mixed.

Depending on the operating conditions of each plasma or beam source or the kinetic energy of the particles, the removal rate of the surface layer can vary. Therefore, it is necessary to adjust the treatment time required for the surface activation treatment. For example, the presence of oxygen and carbon contained in the surface layer is confirmed using surface analysis methods such as Auger Electron Spectroscopy (AES, Auger Electron Spectroscopy) and X-ray Photoelectron Spectroscopy (XPS, X-ray Photo Electron Spectroscopy). You may employ | adopt the time which becomes impossible or longer than it as a processing time of a surface activation process.

In order to make the bonding surface amorphous in the surface activation treatment, the irradiation time of the particles may be set longer than the time necessary for removing the surface layer and exposing the new surface. The lengthening time may be set to 10 to 15 minutes, or 5% or more of the time required for removing the surface layer and exposing the new surface. The time for making the bonding surface amorphous in the surface activation treatment may be appropriately set according to the type and nature of the material forming the bonding surface and the irradiation conditions of particles having a predetermined kinetic energy.

In order to make the joint surface amorphous in the surface activation treatment, the kinetic energy of the irradiated particles is set to be 10% or more higher than the kinetic energy necessary for removing the surface layer and exposing the new surface. Good. The kinetic energy of the particles for making the bonding surface amorphous in the surface activation treatment may be appropriately set depending on the type and property of the material forming the bonding surface and the irradiation conditions of the particles.

Here, the “amorphized surface” or “surface with disordered crystal structure” specifically includes an amorphous layer whose presence has been confirmed by measurement using a surface analysis technique or a layer with a disordered crystal structure, This is a conceptual term that expresses the state of the crystal surface assumed when the particle irradiation time is set to be relatively long or the particle kinetic energy is set to be relatively high. It includes a surface in which the presence of an amorphous layer or a surface having a disordered crystal structure is not confirmed by the measurement used. Also, “amorphize” or “disturb the crystal structure” conceptually represents the operation for forming the amorphized surface or the surface in which the crystal structure is disturbed.

In the method using FAB or IG, the Si particle beam can be emitted simultaneously with the Ar particle beam by interposing a material containing Si in the casing. According to this method, the interface is doped with Si, an interface with more active Si is formed, and more OH groups are formed when the hydrophilic treatment is performed, thereby increasing the strength. This is particularly effective for increasing the bonding strength in a vacuum.

For example, when the Si plate is placed on the bottom of the FAB housing and irradiated with 1 kV, 100 mA, Ar 100 ccm, the bonding strength of the Si wafer with oxide film in vacuum is 1.5 J / m ² without the Si plate. However, in the case where a Si plate is inserted, the strength is increased to a bulk breakdown of 2.5 J / m ² or more. In addition, the particle beam treatment by FAB or IG may be transported in the atmosphere or connected as a separate device in addition to being arranged in the joining device.

<Hydrophilic treatment part>
The hydrophilic treatment unit 620 bonds a hydroxyl group (OH group) to the bonding surface of the substrates 301 and 302 cleaned or activated by the activation processing unit 610.

The hydrophilic treatment by the hydrophilic treatment unit 620 is performed by supplying water (H ₂ O) around the bonding surfaces of the surface activated substrates 301 and 302 in the chamber 200. Therefore, the hydrophilization processing unit 620 includes a water gas generator 621, a valve 622, and a water gas supply pipe 623.

The supply of water is performed by introducing, for example, gaseous water (H ₂ O) into the atmosphere around the surface activated bonding surface. Gaseous water is generated by bubbling the argon (Ar) carrier gas through the water gas generator 621 in the form of bubbles. Gaseous water is mixed with the carrier gas, controlled to a desired flow rate by the valve 622, and introduced into the chamber 200 through the water gas supply pipe 623. The carrier gas at this time is not limited to argon (Ar), and may be nitrogen (N ₂ ), helium (He), oxygen (O ₂ ), or the like.

In addition to the above, water may be water vapor, or may be introduced into the chamber 200 by spraying liquid water in a mist form. Furthermore, as another mode of attaching water to the bonding surfaces of the substrates 301 and 302, radicals, ionized OH groups, or the like may be attached.

Also, the substrate may be cooled in order to allow water to adhere to the bonding surface of the substrate, and the bonding apparatus of this embodiment may include a cooling device for this purpose. Even when the environmental humidity is about 50%, the humidity of the substrate surface can be raised to about 85 to 100% by cooling the substrate.

In the hydrophilization treatment, water, hydroxide, hydroxide ion (OH ⁻ ), hydroxyl radical (· OH), or a substance represented by OH is formed on the bonding surface that has been subjected to the surface activation treatment. OH-containing substances such as ions and radicals (hereinafter also referred to as “water”) are attached to form a layer terminated with a hydroxyl group (OH group) (M—OH) on the bonding surface. Is done.

In the present application, in the hydrophilization treatment step, the substance to be attached to the bonding surface subjected to the surface activation treatment is referred to as “water or OH-containing substance”, these are collectively called “water etc.”, or more simply “water”. However, these notations are a general term for the above substances and are not limited to “water (H ₂ O)”.

It should be noted that the hydrophilization process can be controlled by controlling the humidity of the atmosphere around the bonding surfaces of the surface-activated substrates 301 and 302. The humidity may be calculated as relative humidity, may be calculated as absolute humidity, or other definitions may be employed.

The introduction of water is preferably controlled so that the relative humidity in the atmosphere around at least one or both of the joint surfaces of both substrates is 10% to 90%.

For example, when gaseous water is introduced using nitrogen (N ₂ ) or oxygen (O ₂ ) as a carrier gas, the total pressure in the chamber is 9.0 × 10 ⁴ Pa (Pascal), that is, 0.89 atm (Atom ) And the amount of gaseous water in the chamber is 8.6 g / m ³ (gram / cubic meter) or 18.5 g / m ³ (gram / cubic meter) in absolute volume humidity, 23 ° C. (23 degrees Celsius) The relative humidity can be controlled to be 43% or 91%, respectively. Also, for example, when copper (Cu) is exposed to an atmosphere containing gaseous water of 5 g / m ³ (gram / cubic meter) to 20 g / m ³ (gram / cubic meter) in absolute volume, 2 nm (nanometer) It is assumed that a copper oxide layer of about 14 nm (nanometer) is formed.

Further, the atmospheric concentration of oxygen (O ₂ ) in the chamber may be 10%.

Further, in order to perform the hydrophilic treatment, air outside the chamber having a predetermined humidity may be introduced. When air is introduced into the chamber, it is preferable that the air passes through a predetermined filter in order to prevent unwanted impurities from adhering to the bonding surface. By introducing the atmosphere outside the chamber having a predetermined humidity and performing the hydrophilic treatment, the configuration of the apparatus for performing the hydrophilic treatment on the joint surface can be simplified.

Alternatively, water (H ₂ O) molecules or clusters may be accelerated and radiated toward the bonding surface. The acceleration of the water (H 2 _O), may be used, such as particle beam source used for the surface activation treatment. In this case, a mixed gas of carrier gas and water (H ₂ O) generated by bubbling or the like is introduced into the particle beam source, thereby generating a water particle beam, and on the joint surface to be hydrophilized. It can be irradiated towards. Further, the hydrophilization treatment may be performed by converting water molecules into plasma and bringing it into contact with the joint surface in an atmosphere near the joint surface.

In addition, after the surface activation treatment by particle beam irradiation, exposure to plasma, etc., water washing may be performed as a hydrophilic treatment to remove particles (contaminated particles). By this water washing, the same effect as the above hydrophilic treatment can be obtained.

Note that As hydrophilic treatment, You may perform the same kind or different kind of hydrophilic treatment in multiple times. Also, As part of the hydrophilization treatment, Or after hydrophilization treatment Water molecules may be forced to adhere to the joint surface. This The amount of water molecules on the joint surface can be increased or controlled. Moreover, Thereby, the critical pressure can be adjusted.

The surface where the surface activation treatment and the hydrophilization treatment have been performed is bonded with water molecules intervening as described above, but hydrogen bonds between OH groups can be achieved by removing water molecules. By attracting each other, a relatively strong temporary joint is formed. Further, since a bonding interface including hydrogen and oxygen is formed, hydrogen and oxygen are released to the outside of the bonding interface by the heat treatment in the main bonding, and a clean bonding interface can be formed.

In the present embodiment, the method of applying pressure and the method of heating were shown as the bonding method. However, by applying pressure exceeding the critical pressure, for example, by pressurizing at 10 MPa, water molecules are pushed to join between OH groups. Change. Also, by applying heat, water molecules are removed from the interface and changed to bonding between OH groups. After that, by continuing the heating, the hydrogen bond is changed to the covalent bond, and a transition is made to a strong main junction state.

Also, the same temporary bonding state can be maintained by bonding after leaving water in a vacuum for a long time to blow off water molecules. Bonding can be performed by applying pressure from a bonding state in which water molecules intervene, or bonding in a vacuum. Thereafter, heating can be used in combination in order to make a transition to strong bonding. It is also possible to make a transition to strong bonding from the beginning by heating. However, in consideration of alignment accuracy, since heating involves thermal expansion of the substrate, it is effective to heat in a state where the substrate is temporarily bonded by pressurization or bonding in vacuum.

Oxide may be formed on the joint surface by the hydrophilic treatment. However, after surface activation treatment, it is possible to form a hydroxyl (OH) group directly on the new surface without adhesion of impurities by continuously adhering water, etc. Thus, water molecules adhere to the hydroxyl (OH) group. Since this oxide is relatively controlled (for example, a thickness of several nm or several atomic layers or less), it does not particularly deteriorate electrical characteristics. By heat treatment after pasting, it can be absorbed in the metal material, or can be eliminated or reduced by escaping from the bonding interface as water. Therefore, in this case, it is considered that there is almost no practical problem in the conductivity through the bonding interface with the substrate.

∙ There are cases where it is possible to move while maintaining the contact state during correction movement, or to move after opening a gap. If water molecules are present and the contact area is small, they can move even in contact. What is necessary is just to open about several micrometers when opening a clearance gap.

<Join method>
Next, a method for bonding the substrates 301 and 302 executed by the substrate bonding apparatus 100 according to the present embodiment will be described with reference to FIG.

First, a measurement process for measuring the inter-stage distance and the wafer thickness is executed (step S100). The measurement process is performed before the process of bending the central portion of the substrate. In this measuring step, a distance measuring step for measuring the distance between the stages 401 and 402 by the above-described distance measuring unit, and a thickness measuring step for measuring the thicknesses of the substrates 301 and 302 by the above-described wafer thickness measuring unit, respectively. Executed.

Instead of the measurement step of measuring the interstage distance and the wafer thickness, the substrate is held in a state where only one of the substrates 301 (or the substrate 302) is held before the step of bending the central portion of the substrate. The distance between the stage 402 (or stage 401) not held and the held substrate may be measured, and the distance between the substrates 301 and 302 may be calculated from the measurement result and the measurement result of the wafer thickness measuring means. . Alternatively, the distance between the bonding surfaces of the substrate 301 and the substrate 302 may be measured in a state where the substrate 301 and the substrate 302 are held on the stages 401 and 402.

Next, a hydrophilic treatment process is executed (step S101). In this hydrophilic treatment process, the hydrophilic treatment is performed on the surfaces of the bonding surfaces of the substrate 301 and the substrate 302. In the hydrophilic treatment process, first, as shown in FIG. 3, the substrate 301 is held by a holding mechanism (not shown) of the stage 401 of the substrate bonding apparatus 100, and the outer periphery of the substrate 302 is held by the holding mechanism (not shown) of the stage 402. The part 302s is held. In this state, the substrate 301 and the substrate 302 are opposed to each other with their bonding surfaces being separated from each other. At this time, the chamber 200 is opened to the atmosphere, and the atmosphere is introduced into the atmosphere around the substrates 301 and 302 in the chamber 200.

Next, in the activation treatment unit 610 of the hydrophilic treatment means 600, the bonding surfaces of the substrates 301 and 302 are activated by any of the activation treatment methods described above. For example, plasma-processed argon (Ar) is caused to collide with the bonding surfaces of the substrates 301 and 302 to perform a sputtering process. Then, the surface layer of the bonding surfaces of the substrates 301 and 302 is removed, and the nascent surface of the substance to be bonded is exposed, and the crystal structure in the vicinity of the exposed nascent surface is disturbed and becomes amorphous. Subsequently, in the hydrophilic treatment unit 620, the activated bonding surfaces of the substrates 301 and 302 are hydrophilized by any of the hydrophilic treatment methods described above. For example, the water gas generator 621 generates gaseous water, and the generated gaseous water is introduced into the chamber 200 through the water gas supply pipe 623 together with the carrier gas. When a hydrophilic treatment is performed by attaching an OH-containing substance such as water to the bonding surfaces of the substrates 301 and 302 that have been subjected to the surface activation treatment, the bonding surfaces are terminated with hydroxyl groups (OH groups) (M-OH). ) Is formed.

Note that the order of the interstage distance and wafer thickness measurement step (step S100) and the hydrophilization treatment step (step S101) may be reversed. These orders depend on the configuration of the chamber.

Subsequently, an alignment process of the substrates 301 and 302 is executed (step S102). In this alignment step, alignment between the substrate 301 and the substrate 302 is performed. This is related to transmitted light and reflected light of illumination light emitted from the respective coaxial illumination systems of the cameras 501 and 502 in the position measuring means 500 in a state where the substrate 301 in a bent state and the substrate 302 face each other. Using the image (image data) GA, the positions of both the substrates 301 and 302 are recognized. The position measuring means 500 acquires the image GAa including the alignment marks MK1a and MK2a and the image GAb including the alignment marks MK1b and MK2b (FIG. 12), and attached to both the substrates 301 and 302 based on the images GAa and GAb. The position of each set of marks (MK1a, MK2a), (MK1b, MK2b) is recognized. Based on the relative positions of the recognized marks (MK1a, MK2a), (MK1b, MK2b), the controller 700 determines the amount of positional deviation (Δxa, Δya) (Δxb) between the marks (MK1a, MK2a), (MK1b, MK2b). , Δyb) is obtained (FIG. 13).

The controller 700 detects X from the desired positions of the substrates 301 and 302 based on the positional deviation amounts (Δxa, Δya) and (Δxb, Δyb) of the two sets of marks (MK1a, MK2a) and (MK1b, MK2b). A relative deviation amount ΔD (specifically, Δx, Δy, Δθ) in the direction, the Y direction, and the θ direction is calculated. Next, the controller 700 finally adjusts the substrates 301 and 302 to the correction amounts −ΔD (−Δx, −Δy, and −Δθ) corresponding to the relative deviation amounts ΔD (Δx, Δy, Δθ) between the substrates 301 and 302. ) To calculate a correction movement path that only moves. Then, the controller 700 instructs the drive mechanisms 403 to 407 of the stages 401 and 402 to move both the substrates 301 and 302 according to the calculated correction path.

The stage driving mechanisms 403 and 404 drive the stage 402 in two translational directions (X direction and Y direction) and a rotational direction (θ direction) in accordance with an instruction from the controller 700, whereby both substrates 301 and 302 are driven. Are relatively moved, and the positional deviation amount ΔD is corrected.

Thereafter, a step of bending the substrate is executed (step S103). In the step of bending the substrate, as shown in FIG. 5, with the substrate 301 and the substrate 302 facing each other, the substrate 302 has a central portion 302c with respect to the outer peripheral portion 302s of the bonded surface. It bends so that it may protrude to the 301 side. For this purpose, in the upper stage 402, the protrusion mechanism 430 built in the central portion of the support surface that supports the substrate 302 is protruded toward the lower stage 401. Here, as shown in FIG. 7, the substrate 301 is bent so that the central portion 301c protrudes toward the substrate 302 with respect to the outer peripheral portion 301s of the bonding surface, and the substrate 302 is changed to the outer peripheral portion 302s of the bonding surface. On the other hand, the central portion 302c may be bent so as to protrude toward the substrate 301 side.

Next, a butting process for matching the central portions of the substrates 301 and 302 is performed (step S104). FIG. 15 is a front sectional view showing a state in which the central portion of the bent substrate is abutted against the upper substrate. In the butting step, as shown in FIG. 15, the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are butted at the center. For this purpose, the stage 402 is moved to the lower stage 401 side along the Z direction in the Z direction elevating drive mechanism 406 of the stage drive mechanism 404. Then, the substrate 301 held on the stage 401 in a state where the central portion 301 c is bent so as to be convex upward is abutted against the substrate 302 held on the upper stage 402. Thereby, the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are abutted at the center. In this state, since air is introduced into the chamber 200, the bonding surface between the substrate 301 and the bonding surface of the substrate 302 is terminated with a hydroxyl group (OH group) on the bonding surface by hydrophilization treatment ( M-OH) layer is interposed.

In the center push method that pushes out the central portion of the substrate, in the conventional center push (one side center push) joining method that pushes out the central portion of the substrate from either one of the upper and lower sides, the wafer is bent and joined with several hundred μm, There is a problem in that distortion due to bending occurs and the wafer is warped after bonding due to the difference in elongation between the central portion and the peripheral portion. In addition, since the alignment gap and the center push gap are large, there is a problem that an error occurs at a position where the contact is actually made. FIG. 16 is a diagram for explaining a center push bonding method of pushing out the central portion of the substrate from above.

On the other hand, as described with reference to FIG. 7, there is a method in which the center push is performed from above and below by bending the substrates 301 and 302 on both the stages 401 and 402. In this high-accuracy low strain bonding method (both sides center push bonding method), alignment is performed by bringing the alignment gap close to the limit of contact with the wafer (for example, 10 μm or less), and center push bonding is performed at that position. As a result, errors due to the head lowering do not occur. Further, by performing the center push from above and below, the strain between the upper and lower wafers can be eliminated. As a result, joining without distortion and distortion is possible. Thereafter, as the wafer bonding proceeds, the head is lowered to the zero gap position and released. FIG. 17 is a diagram illustrating the center push bonding method according to the present embodiment.

In order to determine the marginal alignment, center push gap and release point, it is necessary to calibrate the parallelism of the stage and the gap in units of microns, and to correct the thickness variation (2 to 10 μm) of each wafer. The method will be described below.

<How to calibrate stage parallelism and gaps in microns>
18A and 18B are diagrams illustrating a method of calibrating the parallelism and gap of the stage in units of microns. Specifically, a laser sensor (not shown) is provided for the stage and head described in FIG. Then, the size of three gaps (A, B, C) between the stage 401 and the stage 402 is measured with a laser, and the distance G1 is obtained to read the parallel deviation and the gap error. Based on the read result, the stage 402 is feedback-corrected by using the protruding mechanism 412 so that the parallelism and gap are set in advance. Actually, calibration can be performed every day in a necessary situation by pressing a calibration button (not shown) linked to these devices.

<Method for adjusting gap by correcting wafer thickness variation>
FIG. 19 is a diagram for explaining a method of adjusting the gap by correcting the wafer thickness variation. First, using the wafer thickness measuring means, the wafer thickness of the substrates 301 and 302 is measured at three locations with a laser from above and below at the aligner position. After the substrate bonding apparatus 100 moves so as to keep the specified gap between the stage 401 and the stage 402 before the new substrates 301 and 302 are inserted, three gaps between the stage 401 and the stage 402 (A , B, C) are measured to determine the distance G1. The distance G2 between the substrates 301 and 302 is automatically calculated from the wafer thicknesses t1 and t2 of the substrates 301 and 302 and the distance G1 between the stage 402 and the stage 401 measured in advance with the substrates 301 and 302 actually inserted and held. And feed back to the Z-axis. By doing so, a marginal alignment gap and zero point release can be achieved. Further, the laser measurement positions on the stages 401 and 402 may not be three points. One point is also acceptable. Further, it may not be performed every time the wafer is replaced, but may be performed in a timely manner or a specified number of times.

Subsequently, a temporary bonding step for temporarily bonding the substrates 301 and 302 to each other is executed (step S104-2). In this temporary bonding step, in a state where the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are in contact with each other at the center, the Z-direction lifting drive mechanism 406 is driven to lower the stage 402, and at least one substrate 301 is moved. , 302 is applied with a pressure below a certain value or a pressure below a critical pressure. The application of pressure may be started simultaneously with the contact, or may be started after a certain time has elapsed after the contact. Moreover, the application of pressure may be performed over a part of time in the contact state, or may be performed over the whole. Furthermore, the application of pressure may be performed intermittently, and a constant pressure may be maintained during application, or may be changed with time. In addition, even if it separates in the middle, it can bond on the whole surface. If it is pushed in until it is completely pasted, pressure is applied and shifts, so it is not limited to the position where the entire surface is pressed.

“The critical pressure of the joint surface” can be defined as a pressure at which a desired characteristic of the joint surface is changed or lost when the joint surface is pressed with a pressure exceeding that. For example, if too much pressure is applied to the bonding surface in the contact step (temporary bonding) before the step of finally forming the bonding interface (main bonding), the substrates 301 and 302 cannot be bonded and separated. Alternatively, it may be separated, and even if contact is made again and pressure is applied, desired bonding may not be possible. Therefore, if the pressure applied to the bonding surface in the contact process is reduced, the substrates 301 and 302 that are in contact with each other can be separated while the substrates 301 and 302 remain in a non-bonded state without impairing surface characteristics for performing desired bonding. Can do. As described above, the lowest pressure at which the substrates 301 and 302 can be separated thereafter may be defined as the critical pressure.

Alternatively, when the contact and separation are repeated a plurality of times, the separation can be made. However, due to the repeated contact or contact, characteristics such as desired bonding strength cannot be obtained even if a joining step is performed thereafter. For example, even if the newly formed surfaces come into contact with each other at a part of the contact interface and a locally or microscopically strong bonding interface is formed, the substrates 301 and 302 may be separated with a relatively small force. However, even if the substrates 301 and 302 themselves can be separated from each other, surface properties deteriorate due to destruction of the strongly formed bonding interface due to the separation, and as a result, desired bonding characteristics cannot be finally obtained. In this case, it is possible to sufficiently avoid the exposure and contact of the new surface by reducing the pressure applied to the joint surface in the contact step. As described above, when the cause is that the pressure applied to the joint surface in the contact process is substantially high, even if the contact and separation are repeated a plurality of times by lowering the pressure, the desired result is finally obtained. It becomes possible to obtain bonding strength. The pressure in the contact step that can be separated as described above and finally obtain a desired bonding strength may be defined as a critical pressure.

The critical pressure may be defined as a pressure at which a desired bonding cannot be performed when a pressure higher than that is applied, and a pressure at which a desired bonding cannot be performed when a pressure exceeding the critical pressure is applied. Also good.

The critical pressure can be determined according to various factors such as the material forming the joint surface, the presence or absence of a surface layer on the joint surface, the characteristics of the surface layer, and the surface energy. Therefore, the bonding method of the present application may include a step (not shown) of determining the critical pressure of the bonding surface of at least one of the substrates 301 and 302 before the temporary bonding step (step S104-2). .

The pressure applied in the temporary bonding step (step S104-2) is preferably equal to or lower than the critical pressure of the smaller critical pressure defined on both bonding surfaces of the substrates 301 and 302. Thereby, it is possible to ensure that an appropriate pressure is applied to any joint surface of the substrates 301 and 302. In the case where the critical pressure is not defined on one joint surface, a pressure that is equal to or lower than the critical pressure of the other joint surface on which the critical pressure is defined may be applied.

Thereafter, a relative position measurement step (position shift amount measurement step) is executed (step S104-3). In this relative position measurement step, after the temporary bonding step (step S104-2), the relative positional relationship between the bonding surfaces of the substrates 301 and 302 in which the central portions are in contact with each other or the relative positions of both bonding surfaces is measured. To do. For this purpose, the position measuring means 500 uses the images (image data) GA relating to the transmitted light and reflected light of the illumination light emitted from the respective coaxial illumination systems of the cameras 501 and 502 to be attached to both the substrates 301 and 302. Further, the positions of the respective marks (MK1a, MK2a) and (MK1b, MK2b) are recognized. Based on the relative positions of the recognized marks (MK1a, MK2a), (MK1b, MK2b), the controller 700 determines the amount of positional deviation (Δxa, Δya) (Δxb) between the marks (MK1a, MK2a), (MK1b, MK2b). , Δyb).

As described above, when the relative position of the bonding surfaces of the substrates 301 and 302 is measured in a state under contact pressure, the relative position of the bonding surfaces is the final bonding state in a state where contact and pressure are applied. Get closer to. For this reason, a more accurate and uniform contact state can be formed or maintained by pressurization.

Next, a determination step for determining whether or not the relative positional deviation amount is within the allowable error range is executed (step S104-4). Whether or not the positional deviation amount is within a predetermined allowable error range satisfies the condition that all the three positional deviation amounts (Δx, Δy, Δθ) are within the respective allowable error ranges. It may be determined based on whether or not.

If it is determined in the above-described determination step that the relative positional deviation amount is not within the allowable error range (step S104-4: No), a corrected movement amount calculation step is executed (step S104-5). In this correction movement amount calculation step, the correction movement amounts of the substrates 301 and 302 are determined. In the correction movement amount calculation step, the correction movement amounts of the substrates 301 and 302 for moving from the relative position measured in the relative position measurement step (step S104-3) to the desired relative position are obtained. For this purpose, the controller 700 selects desired values of both substrates 301 and 302 based on the positional deviation amounts (Δxa, Δya) and (Δxb, Δyb) of the two sets of marks (MK1a, MK2a) and (MK1b, MK2b). A relative deviation amount ΔD (specifically Δx, Δy, Δθ) in the X direction, Y direction, and θ direction from the position is calculated. Next, the controller 700 finally adjusts the substrates 301 and 302 to the correction amounts −ΔD (−Δx, −Δy, and −Δθ) corresponding to the relative deviation amounts ΔD (Δx, Δy, Δθ) between the substrates 301 and 302. ) To calculate a correction movement path that only moves. For example, the contact state of the joint surface is once released from the relative position measured in the relative position measurement step (step S104-3), that is, the joint surface is separated, and the substrates 301, The movement path may be formed so that the bonding surfaces are brought into contact again with the relative movement of 302. That is, in the following relative position measurement step (step S104-3), the bonded surfaces that have been in contact with each other or the substrates 301 and 302 that have been in contact with each other are separated and contacted again after the movement of the correction movement amount. Further, from the relative position measured in the relative position measurement step, the pressure in the contact state of the joint surface is once removed or reduced, and the substrates 301 and 302 remain in contact with each other at the center. The movement path may be formed by relatively moving the substrates 301 and 302 in a direction substantially parallel to the bonding surface and pressurizing again. The formation of the above movement path is an example, and the present invention is not limited to this.

The corrected movement amount may be determined as a function of a predetermined parameter. The measured relative positions of the substrates 301 and 302 are preferably one parameter that is taken into account by the function. The parameters of the function may include parameters other than the relative positions of the measured substrates 301 and 302. As described above, the movement paths of the substrates 301 and 302 for correcting the relative position can take various shapes, and therefore, the habits and errors of the movement mechanism or measurement mechanism of the substrates 301 and 302 at that time are considered as parameters. May be.

Next, a release process is performed in which the substrates 301 and 302 temporarily bonded to each other are released from each other (step S104-6). In this release step, the distance between the outer peripheral portion 301 s of the substrate 301 and the outer peripheral portion 302 s of the substrate 302 is increased in a state where the central portions of the substrates are abutted so as to maintain a certain distance. Return the deflection.

Subsequently, a position correction process for correcting the relative positions of the substrates 301 and 302 is executed (step S104-7). In this position correction step, the substrates 301 and 302 are moved by the correction movement amount determined in the correction movement amount calculation step (step S104-5). Alternatively, the substrates 301 and 302 are moved according to the obtained movement route. Thereby, the measured misalignment is corrected or minimized. For this purpose, the controller 700 instructs the drive mechanisms 403 to 407 of the stages 401 and 402 to move both the substrates 301 and 302 according to the correction path calculated in the correction movement amount calculation step (step S104-5). Put out. The stage driving mechanisms 403 and 404 drive the stage 402 in two translational directions (X direction and Y direction) and a rotational direction (θ direction) in accordance with an instruction from the controller 700, whereby both substrates 301 and 302 are driven. Are relatively moved, and the positional deviation amount ΔD is corrected.

When the movement of the substrates 301 and 302 includes a movement path in a state in which the substrates 301 and 302 are separated from each other, the joint surfaces are brought into contact with each other at the center and brought into contact again. In addition, when the substrates 301 and 302 move while maintaining the contact state without separating the substrates 301 and 302 or the bonding surfaces, the substrates 301 and 302 are brought into contact with each other at the center when the movement is completed. A contact state is realized.

Then, after the position correction step (step S104-7), the process returns to the step of bending the substrate 301 (step S103). Then, the position correction process (step S104-7) is repeated from the matching process (step S104) of the substrates 301 and 302 until the measured displacement amount of the substrates 301 and 302 falls within the allowable error range. Accordingly, it is possible to perform positioning between the substrates 301 and 302 with high accuracy and finally form a bonding interface or a bonding interface having high positioning accuracy between the substrates 301 and 302.

On the other hand, when it is determined that the relative positional deviation amount is within the allowable error range (step S104-4: Yes), a bonding step of bonding the substrates 301 and 302 to each other is executed (step S105). In the bonding step, first, the projecting mechanism 430 is immersed in the stage 402 as indicated by an arrow AR21 in FIG. Note that “depress the protrusion mechanism 430 into the stage 402” means that the pressing member 434 of the protrusion mechanism 430 is inserted into the stage 402 in detail. Hereinafter, the same applies to the present specification. At this time, the substrates 301 and 302 maintain a state in which the central portions thereof are in contact with each other with a pressure that maintains a non-bonded state. Next, as shown by an arrow AR22 in FIG. 20B, the upper stage 402 is moved in a direction approaching the lower stage 401 by the Z-direction lifting drive mechanism 406. Thereby, the substrate 302 is pressed against the substrate 301, the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 is reduced, and the substrates 301 and 302 are bonded to each other over the entire surface. In this bonding step, for example, the distance between the central portion of the substrate 301 and the central portion of the substrate 302 may be maintained by immersing the protruding mechanism 430 into the stage 402. Even in this case, by moving the upper stage 402 toward the lower stage 401, the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 is reduced, and the substrates 301 and 302 are overlapped with each other. Become.

7 and 17, the so-called center push method in which the substrates 301 and 302 are bent by both the stages 401 and 402 is adopted. In this case, in the bonding step, as shown by arrows AR23 and AR24 in FIG. At this time, the substrates 301 and 302 maintain a state in which the central portions thereof are in contact with each other with a pressure that maintains a non-bonded state. Next, as shown by an arrow AR25 in FIG. 21B, the upper stage 402 is moved in a direction to approach the lower stage 401 by the Z-direction lifting drive mechanism 406. Thus, the substrate 302 is pressed against the substrate 301, the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 is reduced, and the substrates 301 and 302 are brought into contact with each other over the entire surface.

In the bonding step, when the substrate 302 is released from the upper stage 402, first, a holding means such as a vacuum chuck for holding the substrate 302 is released, and then the vacuum suction of the lower stage 401 is operated and the lower side is operated. If the center portion of the substrate 301 is bent, the bending is also restored. Thereafter, it is preferable that the upper stage 402 is raised by the Z-direction lift drive mechanism 406.

In addition, when the state where the entire surface of the substrate is abutted by the Z-direction lifting drive mechanism 406 is compared with the state where the substrate 302 is opened from the upper stage 402, the position of the substrate abutted in the Z direction by about 10 μm to a maximum of 40 μm. May shift. This is because the substrate 301 or 302 before being abutted is warped or distorted. Because of this warpage and distortion, the apparent thickness is larger than the actual thickness of the board before the butting, but when the boards are brought together, the warping and distortion of the board is caused by the attractive force acting between the boards. Forced. For this reason, in the Z direction, a difference of about 10 μm to a maximum of about 40 μm occurs between the point where the entire surface of the substrate abuts and the point where the substrate is released from the stage.

Thereafter, the bonding process of the substrates 301 and 302 is performed (step S106). In this bonding step, as shown in FIG. 20B, bonding is performed after the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are abutted on the entire surface. Here, in this bonding step, pressure may be applied to the bonding surfaces in which the bonding surfaces of the substrates 301 and 302 are in contact with each other. The pressure applied in a state where the bonding surfaces of the substrates 301 and 302 are abutted on the entire surface is preferably a pressure equal to or higher than the critical pressure or a pressure exceeding the critical pressure. Thereby, the bonding surfaces of the substrates 301 and 302 can be further adhered in the final contact process.

The pressurization in a state where the bonding surfaces of the substrates 301 and 302 are abutted on the entire surface is mechanically applied to the substrates 301 and 302 by using a mechanism such as the Z-direction lifting drive mechanism 406 of the substrate bonding apparatus 100, for example. Can be added. In addition, the pressurization in a state where the bonding surfaces of the substrates 301 and 302 are in contact with each other gives an opposite charge to the substrates 301 and 302. You may add with respect to the board | substrate 301,302. The pressurization mode, method, pressure, and the like in a state where the bonding surfaces of the substrates 301 and 302 are abutted on the entire surface are not limited to the above examples, and are appropriately adjusted according to various specific substrate bonding methods. May be.

In addition, the bonding step may include a step of applying heat to the bonding surface in which the bonding surfaces of the substrates 301 and 302 are abutted on the entire surface. By heating, a bonding interface having desired characteristics can be formed. You may form the joining interface which finally has a desired characteristic by heating. By promoting the diffusion of atoms in the vicinity of the bonding surface by heating, the unnecessary surface layer existing on the surface of the bonding surface is finally diffused and removed, forming a bonding interface where the new surface directly contacts. It is possible to reduce the microscopic surface irregularities and increase the area of the substantial bonding interface. Thereby, various characteristics such as mechanical characteristics, electrical characteristics, and chemical characteristics of the bonding interface can be improved. Heating can be performed simultaneously with the above pressurization. Or you may perform a heating and pressurization so that heating time and pressurization time may overlap a part or all. By simultaneously performing heating and pressurization, it is possible to further promote the diffusion of atoms in the vicinity of the bonding surface, improve the characteristics of the obtained bonding interface, and further increase the efficiency of the bonding process.

For example, as described above, in the state in which the bonding surfaces of the substrates 301 and 302 are abutted on the entire surface, by applying an opposite charge to the substrates 301 and 302, the electrostatic attraction due to this charge is used to electrically In addition, the substrates 301 and 302 may be heated while being pressed. Thereby, what is called anodic bonding can be performed.

Heating may be performed by conducting heat from the stages 401 and 402 that support the substrates 301 and 302, or by conducting heat from the gas by heating the gas in the atmosphere of the substrates 301 and 302. It may be performed by irradiating the joint surface with light or the like.

Thus, the final bonding interface between the substrates 301 and 302 may be formed by heating the bonding surfaces of the substrates 301 and 302 together with pressure. In this way, both substrates 301 and 302 are well aligned and final bonding is achieved.

According to the bonding method of the substrates 301 and 302 and the substrate bonding apparatus 100 described above, a step of performing a hydrophilization treatment for attaching water or an OH-containing substance to the surfaces of the bonding surfaces of the substrate 301 and the substrate 302, The substrate 302 is disposed with the bonding surfaces facing each other, the substrate 301 is bent with respect to the outer peripheral portion 301 s of the bonding surface so that the central portion 301 c protrudes toward the substrate 302, and the bonding of the substrate 301 is performed. The outer peripheral portion 301 s of the substrate 301 and the outer peripheral portion 302 s of the substrate 302 are in a state in which the surface and the joint surface of the substrate 302 are abutted with each other at a central portion, and in a state where the central portions are abutted with each other with a pressure that maintains a non-bonded state. , And the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are abutted and bonded to each other. Thereby, it is possible to prevent the generation of voids between the substrates 301 and 302 and to perform bonding with high positional accuracy.

Alternatively, after the step of positioning the substrate 301 and the substrate 302 is performed, the atmosphere around the substrate 302 and the substrate 301 may be evacuated before the substrates 301 and 302 are bonded to each other. Thereby, the process of aligning the substrate 301 and the substrate 302 is performed in the atmosphere. Then, when the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are brought into contact with each other at the center, a state in which water molecules are interposed between the bonding surface of the substrate 301 and the bonding surface of the substrate 302 is maintained. . In this state, since water molecules are sandwiched between the bonding surfaces, the OH groups are not bonded to each other, and the substrates 301 and 302 can be peeled off without affecting the bonding surfaces.

If the step of abutting the bonding surface of the substrate 301 and the bonding surface of the substrate 302 at the center portion is performed in a vacuum, water molecules do not remain sufficiently on the bonding surface. When peeled off, the joint surface will be affected.

Therefore, the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are not bonded, and the alignment between the substrate 301 and the substrate 302 can be repeatedly performed.

On the other hand, when the bonding surface of the substrate 302 and the bonding surface of the substrate 301 are abutted on the entire surface, the surrounding atmosphere is evacuated, so that the intermediate surface is interposed between the bonding surface of the substrate 302 and the bonding surface of the substrate 301. It is possible to prevent air from being mixed into the water. Therefore, voids can be prevented from occurring at the joint between the substrate 302 and the substrate 301. As a result, it is possible to bond the substrates 301 and 302 with high quality while aligning the substrates 301 and 302 with high accuracy.

Further, in the step of aligning the substrate 302 and the substrate 301, the positional deviation amount between the substrate 302 and the substrate 301 is set in a state where the bonding surface of the substrate 302 and the bonding surface of the substrate 301 are abutted at the center. If the measured positional deviation amount exceeds the allowable error range, the relative position between the substrate 301 and the substrate 302 is adjusted so that the positional deviation amount between the substrate 302 and the substrate 301 is reduced, and the position The measurement of the positional deviation amount between the substrate 301 and the substrate 302 and the adjustment of the relative position between the substrate 301 and the substrate 302 were repeated until the deviation amount was within the allowable error range. In this manner, the substrate 301 and the substrate 302 can be aligned with high accuracy by repeating until the positional deviation amount between the substrate 301 and the substrate 302 is within the allowable error range.

The step of measuring the amount of positional deviation between the substrate 301 and the substrate 302 is performed in a state in which the bonding surface of the substrate 301 and the bonding surface of the substrate 302 are brought into contact with each other at a pressure or time that maintains the non-bonded state between the central portions. I made it. When the substrate 301 and the substrate 302 are brought into contact with each other with an excessive pressure or left for a long time, water interposed between the bonding surface of the substrate 301 and the bonding surface of the substrate 302 is expelled, and the substrate 301 and the substrate 302 are discharged. May be joined. Therefore, by maintaining the pressure at which the substrate 301 and the substrate 302 are maintained in a non-bonded state, in other words, maintaining a state in which water is interposed between the bonded surface of the substrate 301 and the bonded surface of the substrate 302, The alignment between the substrate 301 and the substrate 302 can be performed smoothly.

Further, in the step of abutting the bonding surface of the substrate 301 and the bonding surface of the substrate 302 over the entire surface, the substrate 301 is formed into a flat plate shape so as to abut against the bonding surface of the substrate 302. Thus, by making the substrate 301 that has been bent into a flat plate shape, the bonding surface of the substrate 301 and the bonding surface of the substrate 302 can be easily butted together and bonded together.

Further, in the step of abutting the bonding surface of the substrate 301 and the bonding surface of the substrate 302 on the entire surface, the substrates 301 and 302 can be reliably bonded by pressurizing and bonding the substrate 301 and the substrate 302. .

According to one aspect of the present invention, in the above-described bonding method, the step of abutting the first substrate and the second substrate is performed in a state in which the first substrate and the second substrate are abutted at a pressure that maintains a non-bonded state. The distance between the outer peripheral portion of the second substrate and the outer peripheral portion of the second substrate is reduced, and the bonding surface of the first substrate and the bonding surface of the second substrate are butted together and bonded.

In this case, if the bonding surface is pressurized too much, distortion occurs and the position accuracy over the entire surface of the substrate does not appear. In addition, if only one side is bent, distortion may occur during the bonding process, but if both substrates are bent, the distortion may be suppressed during bonding.

Further, the alignment adjustment can be performed again by not increasing the pressure at which the substrates 301 and 302 are bonded to each other.

(Other embodiments)
The substrate bonding method and the substrate bonding apparatus of the present invention are not limited to the above-described embodiments described with reference to the drawings, and various modifications can be considered within the technical scope.

In the above embodiment, the substrate bonding method in which the substrate warpage amount measuring step for measuring the warpage amount of the substrates 301 and 302 held on the stages 401 and 402 is performed immediately before the alignment step (see step S102 in FIG. 14). There may be. For example, as shown in FIG. 22A, the center portions of the substrates 301 and 302 held on the stages 401 and 402 may be warped in a protruding manner. In this case, the distance between the central portions of the substrates 301 and 302 is shorter than the distance G2 obtained by subtracting the thickness of the substrates 301 and 302 from the distance G1 between the stages 401 and 402. For example, it is assumed that the central portions of the substrates 301 and 302 are warped so as to protrude. In this case, when the stage 402 is brought close to the stage 401 so that the distance G2 becomes a desired distance as in the embodiment, the distance between the central portions of the stages 401 and 402 becomes shorter than the desired distance. Therefore, for example, when the total amount of warpage of the central portions of the substrates 301 and 302 is 10 μm or more, the substrates 301 and 302 come into contact with each other when the stages 401 and 402 are brought closer to each other so that the distance G2 becomes 10 μm. The process cannot be performed.

The substrate bonding apparatus according to this modification includes a displacement sensor 435 that detects the position of the protruding mechanism 430 (the position of the pressing member 434 of the protruding mechanism 430), similarly to the substrate bonding apparatus 100 according to the embodiment. In the substrate bonding method according to the present modification, in the warpage amount measurement step immediately before the alignment step, as shown in FIG. 22B, the displacement sensor 435 projects the protrusion mechanism 430 on a flat reference substrate (not shown) without warpage. At the position of the protrusion mechanism 430 in a state where the protrusion mechanism 430 is in contact with the substrate 301 and 302 at a very small pressure. A certain protruding mechanism position is detected (position detecting step). That is, the position of the protrusion mechanism 430 in a state where the protrusion mechanism 430 is brought into contact with the reference substrate at a pressure that does not deflect the reference substrate, and the protrusion mechanism 430 is bent on the substrates 301 and 302. The position of the protrusion mechanism 430 in a state where the contact is made with a pressure having no magnitude is detected. And the board | substrate joining apparatus calculates the curvature amount p1, p2 from the stage 401,402 of the board | substrates 301 and 302 from the difference of the above-mentioned two protrusion mechanism positions detected by the displacement sensor 435 (warpage amount calculation process). . That is, the warpage amounts p1 and p2 of the substrates 301 and 302 from the stages 401 and 402 are calculated from the difference between the first protrusion mechanism position and the second protrusion mechanism position. Then, the stage 402 is brought closer to the stage 401 so that a distance G3 obtained by subtracting the warpage amounts p1 and p2 from the distance G2 becomes a desired distance. Here, the alignment operation of the substrates 301 and 302 may be performed in a state where the stage 402 is brought close to the stage 401 so that the distance G3 becomes a desired distance.

Incidentally, an insulating film such as an oxide film or a nitride film is formed on the bonding surface side of the substrates 301 and 302. When an insulating film is formed only on the bonding surface side (only one side) of the substrates 301 and 302, the substrates 301 and 302 warp so as to protrude toward the bonding surface on which the insulating film is formed. When insulating films are formed on both surfaces of the substrates 301 and 302, an insulating film formed on the bonding surface side of both the substrates 301 and 302 is formed by a CVD (Chemical Vapor Deposition) method. After that, in the case where CMP (Chemical Mechanical Polishing) is performed, the substrates 301 and 302 warp so as to be convex on one side which is a bonding surface thereof. On the other hand, according to the present configuration, even when the substrates 301 and 302 held on the stages 401 and 402 are warped so as to protrude toward the bonding surface, the stages 401 and 402 immediately before the alignment step. It is possible to suppress the substrates 301 and 302 from coming into contact with each other when they are brought close to each other.

In this modification, the example in which the warpage amount of the substrates 301 and 302 is calculated using the protruding mechanism 430 has been described. However, the method for calculating the warpage amount is not limited to this method, and the other substrates 301 and 302 are calculated. A method of calculating the amount of warpage may be employed. For example, in the step of measuring the thickness of the substrates 301 and 302, the amount of warpage of the substrates 301 and 302 may be measured using a laser distance meter.

In the embodiment, it has been described that, in the step of bending the substrate (see step S103 in FIG. 14), the substrates 301 and 302 may be bent as shown in FIG. In this case, in the step of bending the substrate, for example, the larger one of the warpage amount (first warpage amount) of the substrate 301 and the warpage amount (second warpage amount) of the substrate 302 is specified. , 302 may be bent so that the warpage amounts of the respective warpages are equal to or more than the specified warpage amount. Here, the amount of warping of the substrate 301 is the amount of warping of the central portion 301 c of the substrate 301 toward the substrate 302, and the amount of warping of the substrate 302 is the amount of warping of the central portion 302 c of the substrate 302 toward the substrate 301. .

For example, as shown in FIG. 23A, when the warp amount p11 of the substrate 301 is larger than the warp amount p12 of the substrate 302, the substrate bonding apparatus according to this modification first has a large warp amount in the step of bending the substrate. The warp amount p11 of the substrate 301 is specified. Here, for example, as described above, the substrate bonding apparatus determines the position of the protruding mechanism 430 in a state where the protruding mechanism 430 is brought into contact with the substrates 301 and 302 with such a pressure that the substrates 301 and 302 do not bend. The warpage amounts p11 and p12 of the substrates 301 and 302 from the stages 401 and 402 are calculated. Then, the substrate bonding apparatus bends the central portion 302c of the substrate 302 so that the warpage amount of the substrate 302 becomes equal to the specified warpage amount of the substrate 301 (see arrow AR61 in FIG. 23B). Thereafter, the substrate bonding apparatus executes a process of abutting the substrates 301 and 302 (step S104 in FIG. 14).

According to this configuration, since the substrates 301 and 302 are brought into contact with each other in a state where the warpage amounts of the substrates 301 and 302 are equal to each other, the temporary bonding step and the bonding step are performed. Therefore, the two substrates 301 and 302 bonded to each other are performed. The amount of warpage can be reduced.

Further, in the bonding step of the substrate bonding method according to the embodiment, the protrusion mechanism (first protrusion) that contacts the substrate 301 so that the warpage amount of the central portion of the substrate 301 is equal to the warpage amount of the central portion of the substrate 302. Mechanism) The protruding mechanism position of the protruding mechanism (second protruding mechanism) 430 to be brought into contact with 430 or the substrate 302 may be controlled.

For example, as shown in FIG. 23A, it is assumed that the warpage amount of the substrate 301 is larger than the warpage amount of the substrate 302. In this case, as shown in FIGS. 24A and 24B, the substrate bonding apparatus causes the substrate 301 and the substrate 302 to approach each other (see arrows AR71 and AR72 in FIGS. 24A and 24B). The protrusion mechanism position of the protrusion mechanism 430 brought into contact with the central portion 302c of the substrate 302 is controlled so that the warp amount p13 (p15) of 301 is equal to the warp amount p14 (p16) of the substrate 302. Further, the substrate bonding apparatus controls the protrusion mechanism 430 that is in contact with the substrate 301 so that the pressure by which the substrate 301 is pressed by the protrusion mechanism 430 is constant at a preset pressure. That is, when the substrate bonding apparatus lowers the stage 402 in the direction approaching the stage 401, the position of one of the two protruding mechanisms 430 is controlled, and the pressure of the other protruding mechanism 430 is controlled. Here, it is assumed that the protruding mechanism 430 includes a voice coil motor 433, a pressing member 434, and a displacement sensor 435 as shown in FIG. In this case, the protrusion mechanism 430 controls the position of the pressing member 434 based on the detection value detected by the displacement sensor 435. Also in the temporary bonding step, as described above, the protrusion mechanism 430 or the central portion 302c of the substrate 302 that contacts the central portion 301c of the substrate 301 so that the warpage amount of the substrate 301 and the warpage amount of the substrate 302 become equal. The protrusion mechanism position of the protrusion mechanism 430 that is brought into contact with each other may be controlled.

According to this configuration, the bonding process is performed in a state where the warpage amounts of the substrates 301 and 302 are always equal, so that the warpage amounts of the two substrates 301 and 302 bonded to each other can be reduced.

In the substrate bonding method according to the embodiment, the relative positional relationship between the two substrates 301 and 302 temporarily bonded to each other is measured in the relative position measurement step (step S104-3), and the position correction step (step S104-7). ), The example in which the substrates 301 and 302 are moved by the correction movement amount determined in the correction movement amount calculation step (step S104-5) has been described. Here, in the relative position measurement step, the amount of positional deviation in the rotational direction around the other XY direction or Z axis with respect to one of the two substrates 301 and 302 is measured. Note that the XY direction corresponds to a direction orthogonal to the Z direction in which the stages 401 and 402 face each other as described above. However, the type of the amount of displacement measured in the relative position measurement process is not limited to these. For example, in the relative position measurement step, a positional deviation amount corresponding to the warpage amount with respect to the outer peripheral portion of the central portion of the substrates 301 and 302 temporarily bonded to each other may be measured. If the measured displacement amount exceeds the allowable error range, the substrate 301, so that the displacement amount corresponding to the warpage amount is reduced in the step of bending the substrate after the release step is executed. Each of 302 may be bent.

Here, a method of bonding the substrates 301 and 302 executed by the substrate bonding apparatus according to this modification will be described with reference to FIG. First, the substrate bonding apparatus performs a distance and thickness measurement process and a hydrophilization process (steps S200 and S201). The processes in steps S200 and S201 are the same as the processes in steps S100 and S101 described in the embodiment.

Next, the substrate bonding apparatus executes a step of bending the substrate (step S202). Here, for example, as described above, the substrate bonding apparatus specifies the larger amount of warpage between the warpage amount of the substrate 301 and the warpage amount of the substrate 302, and the warpage amounts of the respective substrates 301 and 302 are determined as the specified warpage amount. The center part of the board | substrates 301 and 302 is bent so that it may become above. Subsequently, the substrate bonding apparatus performs an alignment process, a substrate matching process, and a temporary bonding process (steps S203, S204, and S205). The processing in steps S203 to S205 is the same as the processing in steps S102, S104, and S104-2 described in the embodiment.

Thereafter, the substrate bonding apparatus executes a relative position measurement process (step S206). Here, the substrate bonding apparatus has a positional displacement amount in the rotational direction around the other XY direction or Z axis with respect to one of the two substrates 301 and 302, and the outer peripheral portion of the central portion of the substrates 301 and 302 that are temporarily bonded to each other. The positional deviation amount corresponding to the warpage amount is measured. Specifically, as shown in FIG. 26A, the substrate bonding apparatus includes a distance LM1 between the centers of two alignment marks MK1a and MK1b provided on the substrate 301, and two alignment marks MK2a provided on the substrate 302. A distance LM2 between the centers of MK2b is calculated. Then, the substrate bonding apparatus measures the amount of displacement according to the amount of warpage of the substrates 301 and 302 that are temporarily bonded to each other by calculating the difference between the calculated distances LM1 and LM2. Here, as shown in FIG. 26A, when the distance LM1 between the alignment marks MK1a and MK1b of the substrate 301 is longer than the distance LM2 between the alignment marks MK2a and MK2b of the substrate 302, they are temporarily joined together as shown in FIG. The substrates 301 and 302 are warped so as to be convex toward the substrate 302 side. The difference between the distance LM1 and the distance LM2 becomes longer as the warpage amount of the substrates 301 and 302 temporarily bonded to each other is larger.

Returning to FIG. 25, next, the substrate bonding apparatus responds to the relative positional deviation amount of the two substrates 301 and 302 in the XY direction or the rotation direction around the Z axis and the warpage amount of the temporarily bonded substrates 301 and 302. It is determined whether or not the relative positional deviation amount is within an allowable error range (step S207). When the substrate bonding apparatus determines that the relative positional deviation amount is within the allowable error range (step S207: Yes), the substrate bonding apparatus executes a bonding process and a bonding process (steps S212 and S213). The processing in steps S212 and S213 is the same as the processing in steps S105 and S106 described in the embodiment.

On the other hand, when the substrate bonding apparatus determines that the relative positional deviation amount exceeds the allowable error range (step S207: No), it executes a correction movement amount / warpage amount calculation step (step S208). In this correction movement amount / warpage amount calculation step, a desired position is calculated from the relative position measured in the relative position measurement step (step S104-3) in the same manner as the correction movement amount calculation step (step S104-5) described in the embodiment. The correction movement amount of the substrates 301 and 302 for moving to the relative position is calculated. Then, the substrate bonding apparatus determines the warpage amount of each of the substrates 301 and 302 in the substrate abutting step (step S204) for abutting the substrates 301 and 302 together. Specifically, the substrate bonding apparatus includes a protrusion amount of the protrusion mechanism (first protrusion mechanism) 430 that presses the substrate 301 and a protrusion mechanism (second protrusion mechanism) that presses the substrate 302 in the substrate matching step. The protrusion amount of 430 is set.

For example, as shown in FIG. 27A, it is assumed that the substrates 301 and 302 are brought into contact with each other in a state where the warp amount p21 of the substrate 301 and the warp amount p22 of the substrate 302 are equal, and then temporarily joined. At this time, as shown in FIG. 27B, it is assumed that the two substrates 301 and 302 temporarily bonded to each other are warped in a convex shape toward the substrate 302 side. In this case, the distance LM2 between the centers of the alignment marks MK1a and MK1b on the substrate 301 is shorter than the distance LM1 between the centers of the alignment marks MK2a and MK2b on the substrate 302. In this case, as shown in FIG. 27C, the substrate bonding apparatus protrudes to press the central portions 301c and 302c of the substrates 301 and 302 so that the warp amount p22 of the substrate 302 is longer than the warp amount p21 of the substrate 301. The protrusion amount of the mechanism 430 is set. For example, when the substrates 301 and 302 are abutted and temporarily bonded in a state where the warp amount p21 of the substrate 301 and the warp amount p22 of the substrate 302 are both set to 15 μm, the substrates 301 and 302 temporarily bonded to each other are shown in FIG. Suppose you warp as shown. In this case, the substrate bonding apparatus sets the protrusion amount of each protrusion mechanism 430 so that the warp amount p21 of the substrate 301 is 13 μm and the warp amount p22 of the substrate 302 is 17 μm, for example.

On the other hand, as shown in FIG. 28A, when the substrates 301 and 302 are brought into contact with each other in a state where the warping amounts p21 and p22 of the substrates 301 and 302 are equal to each other and temporarily joined, as shown in FIG. Suppose that it is warped in a convex shape. In this case, the distance LM2 between the centers of the alignment marks MK1a and MK1b on the substrate 301 is longer than the distance LM1 between the centers of the alignment marks MK2a and MK2b on the substrate 302. In this case, as shown in FIG. 28C, the substrate bonding apparatus projects the center portions 301c and 302c of the substrates 301 and 302 so that the warp amount p21 of the substrate 301 is longer than the warp amount p22 of the substrate 302. The protrusion amount of the mechanism 430 is set. For example, when the substrates 301 and 302 are abutted and temporarily bonded in a state where the warp amount p21 of the substrate 301 and the warp amount p22 of the substrate 302 are both set to 15 μm, the substrates 301 and 302 temporarily bonded to each other are shown in FIG. Suppose you warp as shown. In this case, the substrate bonding apparatus sets the protrusion amount of each protrusion mechanism 430 so that the warp amount p21 of the substrate 301 is 17 μm and the warp amount of the substrate 302 is 13 μm, for example.

Here, the substrate bonding apparatus determines the protrusion amount of the protrusion mechanism 430 that presses each of the substrates 301 and 302 according to the warpage amount of the central portions 301c and 302c of the substrates 301 and 302 that are temporarily bonded to each other with respect to the outer peripheral portions 301s and 302s. It is set based on the correlation between the amount of misalignment and the amount of protrusion of the protrusion mechanism 430 that presses each of the substrates 301 and 302. Specifically, the substrate bonding apparatus calculates the correlation between the amount of displacement according to the amount of warpage of the substrates 301 and 302 temporarily bonded to each other and the amount of protrusion of the protrusion mechanism 430 that presses each of the substrates 301 and 302. The correlation data shown may be held in advance. Then, the substrate bonding apparatus refers to the correlation data held in advance, and determines each of the substrates 301 and 302 from the amount of displacement according to the amount of warpage of the substrates 301 and 302 temporarily bonded to each other calculated in the relative position measurement step. The protrusion amount of the protrusion mechanism 430 to be pressed is set. In this case, the substrate bonding apparatus acquires correlation data by measuring the amounts of warpage of the substrates 301 and 302 that are temporarily bonded to each other while changing the protruding amount of the protruding mechanism 430 that presses the substrates 301 and 302 in advance. What should I do?

The substrate bonding apparatus is a relational expression showing a correlation between the amount of displacement according to the amount of warpage of the substrates 301 and 302 temporarily bonded to each other and the amount of protrusion of the protrusion mechanism 430 that presses each of the substrates 301 and 302. May be stored in advance. Alternatively, when the substrate bonding apparatus determines that the amount of displacement according to the amount of warpage of the central portions 301c and 302c of the substrates 301 and 302 temporarily bonded to the outer peripheral portions 301s and 302s exceeds the allowable error range, You may make it change the protrusion amount of the protrusion mechanism 430 which presses 301,302 only by the unit amount set beforehand.

Referring back to FIG. 25, subsequently, the substrate bonding apparatus performs a substrate releasing step and a position correcting step (steps S209 and S210). The processes in steps S209 and S210 are the same as the processes in steps S104-6 and S104-7 described in the embodiment.

Thereafter, the substrate bonding apparatus executes a step of bending the substrates 301 and 302 based on the protrusion amount of the protrusion mechanism 430 that presses the substrates 301 and 302, respectively, set in the above-described correction movement amount / warpage amount calculation step. (Step S211). Then, the substrate bonding apparatus executes the process of step S204 again. Then, the step of bending the substrate, the substrate matching step, the relative position measurement step, the correction movement amount / warpage amount calculation step, the substrate release step and the position until the positional deviation amount of the substrates 301 and 302 falls within the allowable error range. The correction process is repeated.

According to this configuration, the bonding process is performed after the positional deviation amount corresponding to the warpage amount of the substrates 301 and 302 temporarily bonded to each other falls within the allowable error range. The amount of warpage 302 can be greatly reduced.

By the way, there are cases where the substrates are repeatedly bonded a plurality of times, as in the case of manufacturing a plurality of substrates bonded to each other. In this case, the warpage amount of each substrate in the substrate matching step, which is set at the time of bonding of one substrate among the bonding of the substrates repeatedly performed a plurality of times, You may make it set as the curvature amount of each board | substrate in the matching process of the board | substrate.

In the releasing step of the above embodiment, gas may be blown into the gap between the peripheral portion of the substrate 301 and the peripheral portion of the substrate 302 in the direction from the peripheral edge of the substrates 301 and 302 toward the central portion of the substrates 301 and 302. . As shown in FIG. 29, the stages 401 and 402 according to this modification have a holding mechanism 3440 that holds the substrates 301 and 302 and a protrusion that bends the substrates 301 and 302 by pressing the central portion of the substrates 301 and 302. And a mechanism 430. The holding mechanism 3440 includes a vacuum chuck having a plurality (four in FIG. 29) of annular suction portions 3440a, 3440b, 3440c, and 3440d. The adsorption portions 3440a, 3440b, 3440c, and 3440d have different diameters and are arranged concentrically. The substrates 301 and 302 are held on the stages 401 and 402 while being sucked by the suction portions 3440a, 3440b, 3440c, and 3440d. Here, the suction portions 3440a and 3440b are opposed to the central portions of the substrates 301 and 302, and the suction portions 3440c and 3440d are opposed to the peripheral portions of the substrates 301 and 302.

The adsorption units 3440a, 3440b, 3440c, and 3440d can take a state of adsorbing the substrates 301 and 302 and a state of not adsorbing the substrates. For example, the suction portions 3440a and 3440b disposed relatively inside the stages 401 and 402 are not vacuum-sucked, and the suction portions 3440c and 3440d disposed relatively outside the stages 401 and 402 are vacuum-sucked. Can be. Further, the radius L1 of the suction part 3440a located closest to the center C1 of the stages 401, 402, the distance L2 between the suction part 3440a and the suction part 3440a adjacent to the outside on the outside, the suction part 3440b and the suction part. The fixed positions of the substrates 301 and 302 are determined by the distance L3 between the adsorbing portion 3440c adjacent to the outer side 3440b and the distance L4 between the adsorbing portion 3440c and the outermost adsorbing portion 3440d.

Immediately before the releasing step according to this modification, as shown in FIG. 30A, the substrate 301 is bent such that the central portion 301c protrudes toward the substrate 302 with respect to the outer peripheral portion 301s of the joint surface. At this time, the two suction portions 3440c and 3440d on the peripheral side of the stage 401 suck the substrate 301, while the two suction portions 3440a and 3440b on the central side of the stage 401 stop sucking the substrate 301 (FIG. (See arrows AR41 and AR42 of 30A). At this time, the stages 401 and 402 hold the substrates 301 and 302 at two suction positions (holding positions) at different distances from the center of the substrates 301 and 302 in the peripheral portions of the substrates 301 and 302. The substrate 302 is bent such that the central portion 302c protrudes toward the substrate 301 with respect to the outer peripheral portion 302s of the bonding surface. At this time, the two suction portions 3440c and 3440d on the peripheral side of the stage 402 suck the substrate 302, while the two suction portions 3440a and 3440b on the center side of the stage 402 stop sucking the substrate 302 (FIG. (See arrows AR41 and AR42 of 30A).

In the release step according to the present modification, as shown in FIG. 30B, the stage 402 is raised and the gap between the substrates 301 and 302 is widened, and the protruding mechanism 430 of the stage 401 is immersed in the stage 401 (see FIG. 30B). 30B) (see arrow AR51 in FIG. 30B), and the projection mechanism 430 of the stage 402 moves in the direction in which the stage 402 is immersed (see arrow AR52 in FIG. 30B). Here, the rising speed of the stage 402 is controlled so that the tensile pressure of the substrate 302 when the substrate 302 is peeled off from the substrate 301 is constant. Then, the suction portions 3440a and 440b on the center side of the stage 401 and the suction portions 3440a and 3440b on the center side of the stage 402 resume suction of the substrates 301 and 302 (see arrows AR61 and AR62 in FIG. 30B). ). Here, the timing at which the suction units 3440a and 3440b resume the suction of the substrates 301 and 302 is such that the protrusion mechanism 430 of the stage 401 is immersed in the stage 401 while the gap between the substrates 301 and 302 is widened, and the protrusion mechanism of the stage 402 430 may be the timing before and after the timing of immersing the stage 402, or may be simultaneous. At this time, the blower 3811 blows gas in the gap between the peripheral portion of the substrate 301 and the peripheral portion of the substrate 302 in the direction from the peripheral edge of the substrates 301 and 302 toward the central portion of the substrates 301 and 302 (FIG. 30B). (See arrow AR6). At this time, a force in a direction in which the substrate 302 is peeled off from the substrate 301 is generated from the differential pressure between the pressure at which the gas is blown by the blower 3811 and the suction pressure at which the adsorption portions 3440a and 3440b adsorb. Thereby, as shown in FIG. 31, the substrate 302 is detached from the substrate 301, and the substrate 301 and the substrate 302 are released.

According to this configuration, since the substrate 302 is easily detached from the substrate 301 in the releasing step, distortion applied to the substrate 301 or the substrate 302 is reduced.

In FIG. 30B, the blower 3811 does not blow gas into the gap between the peripheral portion of the substrate 301 and the peripheral portion of the substrate 302, and the protrusion mechanism 430 is immersed in the stages 401 and 402, and the suction portion. You may make it perform only adsorption | suction of the board | substrates 301 and 302 by 3440a and 3440b.

In the bonding process of the above embodiment, the holding positions of the substrates 301 and 302 by the stages 401 and 402 are changed stepwise toward the outside of the substrates 301 and 302, thereby reducing the distance between the outer peripheral portions of the substrates 301 and 302. The structure which bonds 301,302 together may be sufficient. As shown in FIG. 29, the stages 401 and 402 according to this modification have a holding mechanism 3440 for holding the substrates 301 and 302 and a protrusion that bends the substrates 301 and 302 by pressing the central portion of the substrates 301 and 302. And a mechanism 430.

As shown in FIG. 30A, immediately before the relative position measuring step according to this modification, that is, the bonding step, the substrate 301 is formed such that the central portion 301c protrudes toward the substrate 302 with respect to the outer peripheral portion 301s of the bonding surface. It is bent. At this time, the two suction portions 3440 c and 3440 d on the peripheral side of the stage 401 suck the substrate 301, while the two suction portions 3440 a and 3440 b on the center side of the stage 401 stop sucking the substrate 301. The substrate 302 is bent such that the central portion 302c protrudes toward the substrate 301 with respect to the outer peripheral portion 302s of the bonding surface. At this time, the two suction portions 3440c and 3440d on the peripheral side of the stage 402 suck the substrate 302, while the two suction portions 3440a and 3440b on the center side of the stage 402 stop sucking the substrate 302 (FIG. (See arrows AR41 and AR42 of 30A).

In the bonding step according to this modification, as shown in FIG. 32A, among the suction portions 3440 c and 3440 d sucking the substrates 301 and 302, the suction portion 3440 c on the center side of the stages 401 and 402 is stopped. . That is, by stopping the adsorption of the substrates 301 and 302 in order from the adsorption portion having a short distance from the central portion of the substrates 301 and 302 at the peripheral portions of the substrates 301 and 302, the peripheral portion of the substrate 301 and the peripheral portion of the substrate 302 Contact. Thereby, the contact portion between the substrates 301 and 302 spreads from the central portion of the substrates 301 and 302 toward the peripheral side. Thereafter, as shown in FIG. 32B, the adsorbing portion 440d that adsorbs the substrates 301 and 302 stops, so that the entire bonding surfaces of the substrates 301 and 302 are in contact with each other. After the bonding step, the bonding step (S106) is performed in a state where the entire bonding surfaces of the substrates 301 and 302 are in contact with each other.

According to this configuration, the substrate 301 is held on the stage 401 at four suction positions (holding positions) at different distances from the central portion of the substrate 301 in the peripheral portion of the substrate 301, and the center of the substrate 302 in the peripheral portion of the substrate 302 The substrate 302 is held on the stage 402 at four suction positions having different distances from the part. Then, the suction and holding of the substrates 301 and 302 is stopped in order from the suction position where the distance from the center of the substrates 301 and 302 in the peripheral portion of the substrates 301 and 302 is short, so that the peripheral portion of the substrate 301 (302) (301) is brought into contact with the periphery. Here, one substrate 301 (302) that has been bent comes into contact with the other substrate 302 (301) sequentially from the central portion toward the peripheral side of the substrates 301 and 302 in the process of restoring the original flat plate shape. Go. As a result, the air existing between the two substrates 301 and 302 is pushed out to the peripheral side of the substrates 301 and 302 in the process of restoring one substrate 301 (302) to a flat plate shape. Therefore, when the substrates 301 and 302 are bonded to each other, gas can be prevented from entering between the substrates 301 and 302. Further, by preventing gas from entering between the two substrates 301 and 302, generation of a so-called void between the two bonded substrates 301 and 302 is suppressed.

By the way, in the bonding process described in the above embodiment, the distance between the outer peripheral portion of the substrate 301 and the outer peripheral portion of the substrate 302 is reduced by sandwiching the substrates 301 and 302 between the stages 401 and 402, so that the substrates 301 and 302 are connected to each other. Is in a state of being abutted on the entire surface. In this case, for example, if there are irregularities on the surfaces of the stages 401 and 402 on which the substrates 301 and 302 are placed, the substrates 301 and 302 are deformed along the irregularities when the substrates 301 and 302 are sandwiched between the stages 401 and 402. However, the substrates 301 and 302 may be distorted.

On the other hand, according to this configuration, as shown in FIG. 32B, the substrates 301 and 302 are abutted on the entire surface in a state where the central portions of the substrates 301 and 302 are sandwiched by the protruding mechanisms 430 of the stages 401 and 402. It becomes a state. Therefore, at least in the region excluding the central portion of the substrates 301 and 302, the occurrence of distortion in the substrates 301 and 302 due to the presence of unevenness in the portion where the substrates 301 and 302 are sandwiched is suppressed.

In the modification described with reference to FIGS. 29 to 32, the case where the holding mechanism 3440 is configured by a vacuum chuck has been described. However, the present invention is not limited to this. For example, the holding mechanism is configured by a mechanical chuck or an electrostatic chuck. May be. Alternatively, the holding mechanism may be configured by combining at least two types of chucks among a vacuum chuck, a mechanical chuck, and an electrostatic chuck. Further, in the above-described modification, the holding mechanism 3440 has been described with respect to the example in which the holding unit 3440 is configured by the annular suction units 3440a, 3440b, 3440c, and 3440d. However, the structure of the suction unit is not limited thereto, A structure may be adopted in which the substrates 301 and 302 are sucked through holes opened at a plurality of locations on the upper surface of the lower stage 401 and the lower surface of the upper stage 402.

In the modification described with reference to FIGS. 29 to 31, as shown in FIG. 30A, in the relative position measurement process, the two suction portions 3440 c and 3440 d on the peripheral sides of the stages 401 and 402 are replaced with the substrates 301 and 302. The example in which the two suction portions 3440a and 3440b on the center side of the stages 401 and 402 are stopped sucking the substrates 301 and 302 is shown. However, in order to reduce the positional deviation when the substrates 301 and 302 are bonded to each other, the substrate at the position where the alignment mark is imaged in a state where the temporary bonding between the substrates 301 and 302 is further advanced to the outside of the substrates 301 and 302. It is preferable to detect misalignment between 301 and 302. In this case, the amount of positional deviation between the substrates 301 and 302 when the substrates 301 and 302 are bonded to the outer periphery after the relative position measurement step is reduced. Therefore, for example, as shown in FIG. 33A, in the relative position measurement step, the substrates 301 and 302 may be sucked by only one suction portion 3440d on the peripheral side of the stages 401 and 402. 33A and 33B, components similar to those in the embodiment are denoted by the same reference numerals as in FIG. 1, and components similar to those of the above-described modification are denoted by the same symbols as in FIGS. ing. In this case, the temporary bonding between the substrates 301 and 302 may stop inside the substrate 301 or 302 from the position where the camera 501 or 502 images the alignment mark (see the broken arrow in FIG. 33A). In this case, the positional deviation amount between the substrates 301 and 302 in the bonding process may not be sufficiently reflected as the positional deviation of the alignment mark in the relative position measuring process.

In that case, as shown in FIG. 33B, in the relative position measurement step, for example, from the suction portion 3440a on the center side of the stages 401 and 402, to the gap formed between the substrates 301 and 302 and the stages 401 and 402, Air may be discharged (see arrows AR71 and AR72 in FIG. 33B). In other words, the stage 401 holds the outer peripheral portion of the substrate 301 and the stage 402 holds the outer peripheral portion of the substrate 302, and the center portion of the substrates 301 and 302 is temporarily bonded, so that the stage 401 is placed between the substrate 301 and the substrate 301. Air is discharged to each of the region (first region) S71 and the region (second region) S72 between the stage 402 and the substrate 302. Thereby, the air pressure in the regions S71 and S72 is increased. In this case, as compared with the case described with reference to FIG. 33A, the temporary bonding between the substrates 301 and 302 is advanced to the more peripheral side of the substrates 301 and 302. As a result, the substrates 301 and 302 are temporarily joined to the peripheral sides of the substrates 301 and 302 from the positions where the cameras 501 and 502 capture the alignment marks (see the broken arrows in FIG. 33B).

By the way, in the relative position measurement step, it is preferable to image the alignment mark with the cameras 501 and 502 after the temporary bonding between the substrates 301 and 302 is advanced to the peripheral side of the substrates 301 and 302 as much as possible. In this case, when all the adsorption of the substrates 301 and 302 by the adsorption portions 3440a, 3440b, 3440c, and 3440d is stopped and the substrates 301 and 302 are brought into contact with each other over the entire surface, they are already temporarily joined to the vicinity of the outer peripheral portion. It is difficult for relative displacement of the substrates 301 and 302 to occur. In the case of the substrate bonding method shown in FIG. 33A, it is necessary to execute the relative position measurement process in a state where the temporary bonding is advanced to the outside of the substrates 301 and 302 by reducing the distance between the stages 401 and 402 as much as possible. However, in this case, if there are undulations of about several μm on the mounting surfaces of the substrates 301 and 302 of the stages 401 and 402, a state other than the central portion of the substrates 301 and 302 is in contact and the central portion is not in contact. Can occur. Then, in a state where the substrates 301 and 302 are bonded to each other, there is a possibility that the bonded substrates 301 and 302 are distorted or a void is generated between the substrates 301 and 302. Therefore, the shortening of the distance between the stages 401 and 402 is restricted by the parallelism of the mounting surfaces of the stages 401 and 402. Further, if the substrates 301 and 302 are too close to each other, the substrate 302 may not be peeled from the substrate 301.

On the other hand, in the case of the substrate bonding method shown in FIG. 33B, by increasing the air pressure in the regions S71 and S72 with the substrates 301 and 302 close to each other to some extent, the substrates 301 and 302 are expanded in a direction approaching each other. It is possible to widen the temporary joining portion between 301 and 302 to the peripheral side of the substrates 201 and 302. Accordingly, the region where the substrates 301 and 302 are temporarily bonded can be expanded without bringing the outer peripheral portions of the substrates 301 and 302 too close to each other, so that the substrate 302 is not affected by the undulation of the stage. It can prevent that it does not peel off. Furthermore, the positional deviation amount of the substrates 301 and 302 when the substrates 301 and 302 are attached to each other is reflected in the positional deviation amount of the alignment mark recognized by the cameras 501 and 502. Therefore, it is possible to correct the positional deviation amount by peeling again, and when the substrates 301 and 302 are bonded together on the entire surface in the subsequent bonding process, the substrates 301 and 302 are not displaced from each other without causing a positional shift. Can be pasted together. Therefore, the bonding accuracy between the substrates 301 and 302 is improved.

By the way, even if provisional joining has progressed to the vicinity of the outer peripheral portions of the substrates 301 and 302, the gap between the outer peripheral portions of the substrates 301 and 302 is maintained. In this state, when the substrate 302 is peeled from the substrate 301, if the substrates 301 and 302 are sucked by all the suction portions 3440a, 3440b, 3440c, and 3440d of the stages 401 and 402, the space between the substrates 301 and 302 and the stages 401 and 402 is reduced. A large negative pressure is generated. Then, when the fixing strength of the stages 401 and 402 is small, the stage 401 may be lifted or the stage 402 may be pulled down, and the stage may be damaged. Accordingly, the stage 402 is lifted while air is discharged into the gap between the outer peripheral portions of the substrates 301 and 302, and finally the central portions of the substrates 301 and 302 are sucked by the suction portions 3440a and 3440b located at the central portions of the stages 401 and 402. Thus, a method of peeling the substrate 302 from the substrate 301 is preferable.

Also, it does not necessarily have to be joined to the outside of the mark recognition position. As shown in FIG. 30A, even if it is inside the mark position, if the bonding force is strong, the position shift can be detected. In some cases, the joining may be advanced to the vicinity without exceeding the mark position.

In the above embodiment, in the bonding step, an example in which pressure is applied to the substrates 301 and 302 and the substrates 301 and 302 are heated by the substrate heating unit 420 while the entire bonding surfaces of the substrates 301 and 302 are in contact with each other. . However, the present invention is not limited to this. For example, a configuration in which heating is performed only by applying pressure to the substrates 301 and 302 in a state where the entire bonding surfaces of the substrates 301 and 302 are in contact with each other may be employed. In this case, the substrates 301 and 302 may be heated in an annealing furnace (not shown) separate from the substrate bonding apparatus after being taken out from the substrate bonding apparatus 100.

Alternatively, the substrate bonding apparatus may be configured such that only the substrates 301 and 302 are heated and no pressure is applied in a state where the entire bonding surfaces of the substrates 301 and 302 are in contact with each other.

In the above embodiment, at least a part of the lower stage 401 may be made of a transparent material, or the material constituting the lower stage 401 may be transparent. Thereby, light (including the transmitted light and the reflected light) emitted from the light source for position measurement can pass through the transparent material of the lower stage 401. Therefore, there is no restriction on the design of the substrate support means.

In the above embodiment, at least a part of the substrate heating unit 420 is made of a transparent material, or the material constituting the substrate heating unit 420 is transparent, and the heater 421 in the substrate heating unit 420 is disposed between the heater wires. A predetermined interval may be provided.
Thereby, it can avoid that the wiring of a heater interferes with the light (including the above-mentioned transmitted light and reflected light) emitted from the light source for position measurement. Further, even if the heater wiring interferes with the light emitted from the light source at the initial setting stage, the heater heating circuit 420 on which the heater 421 is mounted is rotated around the Z axis to avoid the heater wiring from the optical path. Can do.

As the transparent material, a glass material or a ceramic material is preferably used. Even if it does not look transparent when viewed with the naked eye, the lower stage 401 may be made of a material that transmits light emitted from the light source.

Further, at least a part of the lower stage 401 is made of a transparent material, or a material constituting the lower stage 401 is transparent, and at least a part of the substrate heating means 420 is made of a transparent material, Or the material which comprises the board | substrate heating means 420 is transparent, and the heater 421 in the board | substrate heating means 420 does not receive restrictions by the design of a board | substrate support means by providing a predetermined space | interval between heater wiring.

For example, in the above-described embodiment, the case where two cameras 501 and 502 are fixedly arranged as the position measuring unit 500 is illustrated, but the present invention is not limited to this, and two alignment marks are moved by moving one camera. You may make it image | photograph each image of the vicinity.

In the above embodiment, the case where the stage 401 is moved in the X direction is illustrated, but the present invention is not limited to this. For example, the stage 401 may be fixed.

In the above embodiment, the stage 402 is moved in the X direction, the Y direction, the Z direction, and the θ direction, so that the stages 401 and 402 are relatively moved in these directions. It is not limited to this. For example, conversely, when the stage 402 is fixed and the stage 401 is moved in the X direction, the Y direction, the Z direction, and the θ direction, the stages 401 and 402 are relatively moved in these directions. It may be.

In the above embodiment, the substrate 301 or 302 having a predetermined shape or material has been described. However, the present invention is not limited to this.

In the embodiment, an example in which the substrates 301 and 302 are formed of a glass substrate, an oxide substrate, or a nitride substrate has been described. However, the present invention is not limited thereto, and the substrates 301 and 302 may be Si substrates. One of the substrates 301 and 302 may be a Si substrate and the other may be a glass substrate. Further, the substrates 301 and 302 may be a substrate on which an oxide film is formed, a substrate on which a nitride film is formed, a carbide substrate, or a ceramic substrate.

In the case where the substrates 301 and 302 are substrates on which an oxide film or a nitride film is formed, the oxide film and the nitride film may be formed by a CVD (Chemical Vapor Deposition) method. In this case, if the thickness of the substrates 301 and 302 is thin to some extent, the substrates 301 and 302 may be warped in a convex shape toward the surface on which the oxide film or nitride film is formed.

Moreover, in the substrate bonding apparatus 100 shown in FIG. 1, the case where the surface activation process is performed inside is illustrated, but the present invention is not limited to this. For example, the surface activation process may be performed outside the substrate bonding apparatus 100. Furthermore, the surface activation treatment can be performed only by opening the chamber 200 and exposing the inside of the chamber 200 to the atmosphere. Other than this, as long as the gist of the present invention is not deviated, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

This application is based on Japanese Patent Application No. 2016-048896 filed on Mar. 11, 2016 and Japanese Patent Application No. 2017-010762 filed on Jan. 24, 2017. The specification, claims and entire drawings of Japanese Patent Application No. 2016-048896 and Japanese Patent Application No. 2017-010762 are incorporated herein by reference.

The present invention is suitable for manufacturing, for example, a CMOS image sensor, a memory, an arithmetic element, and a MEMS.

100: substrate bonding apparatus, 200: chamber, 201: vacuum pump, 202: exhaust pipe, 203: exhaust valve, 301: substrate (second substrate), 302: substrate (first substrate), 301c, 302c, 431c : Central part, 301s, 302s: outer peripheral part, 304: stage moving mechanism, 400: substrate support means, 401: stage (second substrate holding part), 402: stage (first substrate holding part), 403, 404: stage Drive mechanism, 405: XY direction drive mechanism, 406: Z direction elevation drive mechanism, 407: Rotation drive mechanism, 408: Pressure sensor, 411: Stage pressure sensor, 412, 430: Projection mechanism, 420: Substrate heating means, 421: Heater, 430a: crown, 431: pressing plate (pressing member), 431s: outer peripheral portion, 433: voice coil motor, 434: pressing member, 35: displacement sensor, 435a: detection unit, 440, 3440: holding mechanism, 440a: outer holding mechanism, 440b: inner holding mechanism, 500: position measuring means (positioning unit), 501, 502: camera, 503: window, 504: Mirror, 600: Hydrophilization processing means, 610: Activation processing section, 620: Hydrophilization processing section, 621: Water gas generator, 622: Valve, 623: Water gas supply pipe, 700: Controller, 3440a, 3440b , 3440c, 3440d: adsorption part, 3811: blower, 4021: stage main body, 4331: coil bobbin, 4332: coil, 4333: magnet, 4334: yoke, 4342: base part

Claims (29)

1. A method of bonding a first substrate and a second substrate,
   A hydrophilization treatment step of performing a hydrophilization treatment for attaching water or an OH-containing substance to the surfaces of the respective bonding surfaces of the first substrate and the second substrate;
   Bending the substrate for bending the first substrate with respect to the outer peripheral portion of the bonding surface such that a central portion protrudes toward the second substrate;
   A butting step of abutting the joint surface of the first substrate and the joint surface of the second substrate at the central portions;
   In a state where the central portions are in contact with each other so as to maintain a constant distance, the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced, and the bonding surface of the first substrate A pasting step of laminating the joint surface of the second substrate over the entire surface,
   Before or after the matching step, the distance between the first substrate and the second substrate is measured, and the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate Reduce the distance of
   Substrate bonding method.
2. Between the hydrophilic treatment step and the bonding step, the first substrate and the second substrate are arranged with the bonding surfaces facing each other, and the first substrate and the second substrate A positional deviation amount measuring step for measuring the positional deviation amount;
   A position correction step of correcting the relative position between the first substrate and the second substrate so that the amount of positional deviation between the first substrate and the second substrate is small.
   The substrate bonding method according to claim 1.
3. A positional deviation amount measuring step for measuring a positional deviation amount between the first substrate and the second substrate during or after the bonding step;
   When the measured amount of positional deviation exceeds the allowable error range, the outer peripheral portion of the first substrate and the second substrate are in contact with each other so that the central portions keep a constant distance. Releasing the first substrate and the second substrate to be separated from each other by releasing the distance from the outer periphery of the first substrate and then returning the deflection of the central portion of the first substrate;
   A position correction step of correcting the relative position between the first substrate and the second substrate so that the amount of positional deviation between the first substrate and the second substrate is small; and
   Until the displacement amount falls within an allowable error range, the step of bending the substrate, the matching step, the displacement amount measurement step, the release step, and the position correction step are repeated.
   The substrate bonding method according to claim 1.
4. The positional deviation amount includes a positional deviation amount according to a warpage amount with respect to an outer peripheral portion of a central portion of the first substrate and the second substrate temporarily bonded to each other,
   When the measured displacement amount exceeds an allowable error range, the step of bending the substrate after the release step is performed, so that the displacement amount according to the warp amount is reduced in the step of bending the substrate. Deflecting the first substrate and the second substrate;
   The substrate bonding method according to claim 3.
5. A plurality of first alignment marks are provided on the periphery of the first substrate,
   A plurality of second alignment marks are provided on the periphery of the second substrate,
   In the positional deviation amount measuring step, the positional deviation amount corresponding to the warpage amount is measured based on the distance between the plurality of first alignment marks and the distance between the plurality of second alignment marks. ,
   The substrate bonding method according to claim 4.
6. In the step of bending the substrate, the first substrate is bent by pressing the center portion of the first substrate by the first protruding mechanism, and the center of the second substrate is bent by the second protruding mechanism. Bend the second substrate by pressing the part,
   The amount of protrusion of the first protrusion mechanism and the amount of protrusion of the second protrusion mechanism depend on the amount of warpage with respect to the outer peripheral portion of the central portion of the first substrate and the second substrate temporarily bonded to each other. Set based on the correlation between the amount of misalignment and the amount of protrusion of the first protrusion mechanism and the amount of protrusion of the second protrusion mechanism,
   The substrate bonding method according to claim 5.
7. In the positional deviation amount measuring step, the first substrate holding portion that holds the first substrate holds the outer peripheral portion of the first substrate, and the second substrate holding portion that holds the second substrate An outer peripheral portion of the second substrate is held, and in a state where the central portion of the first substrate and the central portion of the second substrate are temporarily joined, the first substrate holding portion and the first substrate Increasing air pressure in the first region and the second region by discharging air to each of the first region and the second region between the second substrate holding part and the second substrate,
   The substrate bonding method according to any one of claims 2 to 6.
8. In the bonding step, at least one of the first substrate holding unit that holds the first substrate and the second substrate holding unit that holds the second substrate is connected to the first substrate holding unit and the second substrate holding unit. The distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced by moving the portions in a direction approaching each other, and the outer peripheral portion of the first substrate and the second substrate are reduced. The outer periphery of the
   The board | substrate joining method as described in any one of Claim 1 to 7.
9. In the matching step, the first substrate is held by the first substrate holding portion at a plurality of holding positions at different distances from the central portion of the first substrate in the outer peripheral portion of the first substrate,
   In the laminating step, the first substrate is released in order from the holding position where the distance from the central portion of the first substrate in the outer peripheral portion of the first substrate is short. Reducing the distance between the outer periphery of the substrate and the outer periphery of the second substrate and bringing the outer periphery of the first substrate into contact with the outer periphery of the second substrate;
   The board | substrate joining method as described in any one of Claim 1 to 7.
10. Before the step of bending the central portion of the substrate, the distance between the first substrate holding portion that holds the first substrate and the second substrate holding portion that holds the second substrate is measured with a laser distance meter. A distance measurement process;
    A thickness measuring step of measuring the thickness of the first substrate and the second substrate;
    A distance calculating step of calculating a distance between the first substrate and the second substrate from the measurement result;
    The distance between the outer periphery of the first substrate and the outer periphery of the second substrate is reduced by the calculated distance between the substrates.
    The substrate bonding method according to claim 1.
11. Prior to the step of bending the central portion of the substrate, the substrate among the first substrate holding portion and the second substrate holding portion is held in a state where only the first substrate or the second substrate is held. A distance measuring step of measuring the distance between one not held and the substrate held on the other with a laser distance meter;
    A thickness measuring step for measuring the thickness of the substrate that is not held;
    A distance calculating step of calculating a distance between the first substrate and the second substrate from the measurement results in the distance measuring step and the thickness measuring step;
    The distance between the outer periphery of the first substrate and the outer periphery of the second substrate is reduced by the calculated distance between the substrates.
    The substrate bonding method according to claim 1.
12. With the first substrate holding unit holding the first substrate and the second substrate holding unit holding the second substrate, the bonding surface of the first substrate and the bonding surface of the second substrate Further comprising a distance measuring step of measuring the distance between them with a laser distance meter,
    Based on the measurement result, the distance between the outer periphery of the first substrate and the outer periphery of the second substrate is reduced.
    The substrate bonding method according to claim 1.
13. When the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced, the bonding surface of the central portion of the first substrate with respect to the bonding surface of the outer peripheral portion of the first substrate Reducing the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate by a protruding distance;
    The substrate bonding method according to claim 1.
14. The positional deviation amount measuring step includes
    The bonding surface of the first substrate and the bonding surface of the second substrate are performed by infrared transmission recognition in a state where the distance between the entire surfaces is maintained in a non-bonded state.
    The substrate bonding method according to any one of claims 2 to 7.
15. Bending the second substrate with respect to the outer peripheral portion of the bonding surface so that a central portion protrudes toward the first substrate, and further abutting the central portion;
    The substrate bonding method according to claim 1.
16. While reducing the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate, the pressure generated on the bonding surface of the substrates is maintained so as not to fall below a certain value, while the first substrate is maintained. Reducing the distance between the outer periphery of the second substrate and the outer periphery of the second substrate,
    The substrate bonding method according to claim 1.
17. When the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is increased, the pressure generated on the bonding surface of the substrates is maintained so as not to fall below a certain value, while the first substrate is maintained. A distance between the outer peripheral portion of the second substrate and the outer peripheral portion of the second substrate,
    The substrate bonding method according to any one of claims 1 to 16.
18. In the laminating step, an operation of detecting a butt position when the detected pressure becomes a certain value or more and increasing or decreasing a distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate. Stop,
    The substrate bonding method according to claim 16 or 17.
19. A warp for measuring a first warp amount of the center portion of the first substrate toward the second substrate side and a second warp amount of the center portion of the second substrate toward the first substrate side. A quantity measuring step;
    A distance calculating step of calculating a distance between the first substrate and the second substrate from the first warpage amount and the second warpage amount;
    The distance between the outer periphery of the first substrate and the outer periphery of the second substrate is reduced by the calculated distance between the substrates.
    The substrate bonding method according to any one of claims 1 to 18.
20. The warpage measuring step includes
    A position detecting step of detecting a protruding mechanism position of the protruding mechanism in a state where the protruding mechanism is in contact with the first substrate or the second substrate;
    Based on the protrusion mechanism position detected in the position detection step, the first warpage amount that is the warpage amount from the first substrate holding portion of the first substrate, or the second amount of the second substrate. A warpage amount calculating step of calculating the second warpage amount that is a warpage amount from the substrate holding portion,
    The substrate bonding method according to claim 19.
21. In the step of bending the substrate, the larger one of the first warpage amount and the second warpage amount is specified, and the warpage of the central portion of the first substrate toward the second substrate side is specified. The central portion of the first substrate and the second substrate so that the amount and the amount of warpage of the central portion of the second substrate toward the first substrate are equal to or more than the specified warpage amount. Bend the center of the board
    The substrate bonding method according to claim 19 or 20.
22. In the laminating step, the protrusion mechanism for contacting the first substrate or the second substrate so that the warpage amount of the central portion of the first substrate is equal to the warpage amount of the central portion of the second substrate. The protruding mechanism position of the protruding mechanism that contacts the substrate is controlled.
    The substrate bonding method according to claim 21.
23. An insulating film is formed on the bonding surface side of the first substrate and the second substrate,
    The substrate bonding method according to any one of claims 20 to 22.
24. Performing the bonding step in a vacuum;
    The substrate bonding method according to any one of claims 1 to 23.
25. After the bonding step, further comprising a joining step,
    In the bonding step, the first substrate and the second substrate are heated and bonded.
    The substrate bonding method according to any one of claims 1 to 24.
26. After the bonding step, further comprising a joining step,
    In the bonding step, the first substrate and the second substrate are pressurized and bonded.
    The substrate bonding method according to any one of claims 1 to 25.
27. Prior to adhering water or OH-containing substance to the bonding surface by the hydrophilization treatment, a surface that causes particles having kinetic energy to collide with the surfaces of the bonding surfaces of the first substrate and the second substrate, respectively. Perform the activation process,
    The substrate bonding method according to any one of claims 1 to 26.
28. The hydrophilic treatment is performed in a vacuum, and water or an OH-containing substance is attached to the joint surface without being exposed to the atmosphere.
    The substrate bonding method according to any one of claims 1 to 27.
29. A method of bonding a first substrate and a second substrate,
    A hydrophilization treatment step of performing a hydrophilization treatment for attaching water or an OH-containing substance to the surfaces of the respective bonding surfaces of the first substrate and the second substrate;
    Bending the substrate for bending the first substrate with respect to the outer peripheral portion of the bonding surface such that a central portion protrudes toward the second substrate;
    A butting step of abutting the joint surface of the first substrate and the joint surface of the second substrate at the central portions;
    In a state where the central portions are in contact with each other so as to maintain a constant distance, the distance between the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate is reduced, and the bonding surface of the first substrate A bonding step of bonding the bonding surface of the second substrate to the entire surface;
    During or after the bonding step, the first substrate and the second substrate including a displacement amount corresponding to a warp amount with respect to an outer peripheral portion of a central portion of the first substrate and the second substrate temporarily bonded to each other. A positional deviation amount measuring step for measuring the positional deviation amount from the substrate
    A position for correcting the relative position of the first substrate and the second substrate, the amount of warpage of the first substrate, and the amount of warpage of the second substrate so that the amount of positional deviation becomes small. A correction step,
    Substrate bonding method.

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