JP6429179B2 - Substrate bonding apparatus and substrate bonding method - Google Patents

Description

  The present invention relates to a technique for bonding substrates.

  In the field of electronics, there is a demand for higher density and efficiency of device mounting. Therefore, a bonding technique called three-dimensional mounting, in which a substrate on which a semiconductor integrated circuit or electrical wiring has already been formed, is bonded to another similar substrate has attracted attention. This method includes COC (chip-on-chip), COW (chip-on-wafer), WOW (wafer-on-wafer) and three-dimensional mounting from the chip level to the wafer level, but wafer-on-wafer (WOW, Wafer-On-) By applying to a wafer having a larger area such as Wafer) or wafer level packaging (WLP), it is possible to stack electric elements and circuits in a direction perpendicular to the surface of the wafer. In addition, an electrical circuit or an electrical wiring formed on one substrate can be bonded to a corresponding electrical circuit or electrical wiring on another substrate at a time in the wafer surface direction. Therefore, this technique enables both the three-dimensional mounting of the semiconductor integrated circuit and the efficiency of the manufacturing method at the same time.

  The surface of the wafer is provided with a metal region that is electrically connected to or connected to the above electric circuit or the like, and the electrical connection is established between these metal regions in the bonding process, so that the wafer is An electrical connection between them is established. In general, in the bonding process, first, alignment in the wafer surface direction is performed between corresponding metal regions of a wafer to be bonded. Next, the wafers are brought close to each other so that the metal regions are in contact with each other, and a force is applied in the direction perpendicular to the wafer surface. When heated to a relatively high temperature, atomic diffusion occurs between the metal regions, and electrical connection is established. Further, between adjacent electrodes is generally filled with an insulating layer in order to avoid a short circuit between the electrodes. As the insulating layer portion, an oxide film, a nitride film, a resin layer, or the like is generally used, and it is preferable to join the insulating layer simultaneously with bonding of the electrodes. In particular, this oxide film or nitride film is not diffusion bonded unless it is at a high temperature of several thousand degrees. Therefore, as a method of bonding at a low temperature, OH groups are attached to the bonding surface to be hydrophilic and bonded with water intervening. In many cases, a method is employed in which water molecules are removed by heating under a transition to a strong covalent bond.

  By the way, bonding at high temperature is not suitable for bonding between thin wafers or different materials having different coefficients of thermal expansion. Therefore, in Patent Document 1, when a wafer having a metal region on the bonding surface is bonded, the wafer bonding surfaces are brought into contact with each other after the surface activation treatment and the hydrophilic treatment are performed on the metal region. A technique for bonding wafers at a relatively low temperature by bonding and heating is proposed.

JP2013-251405A

  By the way, as in Patent Document 1, when wafers that have been subjected to surface activation treatment and hydrophilic treatment are bonded together in the atmosphere, air is entrained between the wafers, leaving large voids that remain unbonded. . Therefore, although it is preferable to join in a vacuum, there exists a subject that there is a limit in improvement of joining strength in a vacuum.

  The present invention has been made in view of the above problems, and aims to improve the bonding strength between substrates and reduce voids between substrates.

The invention according to claim 1 is a substrate bonding apparatus, wherein a surface activation is performed to activate a first bonding surface of the first substrate and a second bonding surface of the second substrate in the vacuum chamber and the vacuum chamber. After activation by the processing unit and the surface activation processing unit, the first bonding surface and the second bonding surface that have been subjected to hydrophilic treatment are brought into contact with each other, and the first substrate and the second substrate are brought into contact with each other. The first substrate and the second substrate are temporarily bonded by pressing against each other, the first substrate after the temporary bonding is separated from the second substrate, and the first substrate in a state of being separated in a vacuum. A substrate bonding mechanism configured to bond the first substrate and the second substrate by bringing a bonding surface and the second bonding surface into contact with each other;

  A second aspect of the present invention is the substrate bonding apparatus according to the first aspect, wherein the temporary bonding of the first substrate and the second substrate is performed in the atmosphere.

  The invention described in claim 3 is the substrate bonding apparatus according to claim 1 or 2, wherein the first substrate and the second substrate after temporary bonding are separated in a vacuum.

  Invention of Claim 4 is the board | substrate joining apparatus in any one of Claim 1 thru | or 3, Comprising: In parallel with the said hydrophilization process, or the temporary joining by the said hydrophilization process and the said board | substrate joining mechanism In between, a water molecule is made to adhere to the 1st joined surface and the 2nd joined surface.

  The invention according to claim 5 is the substrate bonding apparatus according to claim 4, wherein the first bonding surface and the second bonding surface are obtained by cooling the first bonding surface and the second bonding surface. A substrate cooling unit for attaching water molecules to the substrate is further provided.

  Invention of Claim 6 is a board | substrate joining apparatus of Claim 4 or 5, Comprising: Attachment of the water molecule to the said 1st joining surface and the said 2nd joining surface is a water molecule in the said vacuum chamber. It is performed by supplying a gas containing.

  A seventh aspect of the present invention is the substrate bonding apparatus according to any one of the fourth to sixth aspects, wherein the first bonding surface is washed with water with respect to the first bonding surface and the second bonding surface. And a water washing unit for attaching water molecules to the surface and the second joint surface.

The invention according to claim 8 is a substrate bonding method, comprising: a) activating the first bonding surface of the first substrate and the second bonding surface of the second substrate in a vacuum; b) the a) A step of hydrophilizing the first bonding surface and the second bonding surface after the step; c) bringing the first bonding surface and the second bonding surface into contact with each other; A step of temporarily bonding the first substrate and the second substrate by pressing the second substrate against each other; and d) the first substrate and the second substrate temporarily bonded in the step c). And e) contacting the first substrate and the second substrate by bringing the first bonding surface and the second bonding surface in a state of being separated in a vacuum into contact with each other.

  A ninth aspect of the present invention is the substrate bonding method according to the eighth aspect, wherein in the step c), the first bonding surface and the second bonding surface are contacted in the atmosphere.

  A tenth aspect of the present invention is the substrate bonding method according to the eighth or ninth aspect, wherein the step d) is performed in a vacuum.

  Invention of Claim 11 is the board | substrate bonding method in any one of Claim 8 thru | or 10, Comprising: In parallel with the said b) process or the said b) process and the said c) process, The method further includes a step of attaching water molecules to the first joint surface and the second joint surface.

  The invention described in claim 12 is the substrate bonding method according to claim 11, wherein the step f) includes a step of cooling the first bonding surface and the second bonding surface.

The invention according to claim 13 is the substrate bonding method according to claim 11 or 12, wherein adhesion of water molecules to the first bonding surface and the second bonding surface in the step f) is a water molecule. It is performed by supplying a gas containing .

  A fourteenth aspect of the present invention is the substrate bonding method according to any one of the eleventh to thirteenth aspects, wherein the step f) is a step of performing water washing on the first bonding surface and the second bonding surface. including.

  In the present invention, the bonding strength between the substrates can be improved and the voids between the substrates can be reduced.

It is a front view of the board | substrate joining apparatus which concerns on one embodiment. It is a perspective view of a surface activation process part. It is a front view which shows a line type particle beam source, a shielding member, and a board | substrate. It is a front view which shows a line type particle beam source, a shielding member, and a board | substrate. It is a front view which shows a line type particle beam source, a shielding member, and a board | substrate. It is a front view which shows a line type particle beam source, a shielding member, and a board | substrate. It is a figure which shows the flow of joining of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a conceptual diagram which shows the state of the joint surface of a board | substrate. It is a front view which shows the other preferable example of a board | substrate bonding apparatus. It is a top view which shows the other preferable example of a board | substrate bonding apparatus. It is a top view which shows the other preferable example of a surface activation process part. It is a top view which shows the other preferable example of a board | substrate bonding apparatus.

  In the present application, a wafer (hereinafter referred to as “substrate”) includes a plate-shaped semiconductor, but is not limited thereto. In addition to the semiconductor, the “substrate” may be formed of a material such as glass, ceramics, metal, plastic, or a composite material using a plurality of these materials. The material of the substrate includes a material having high rigidity and a material having low rigidity. The “substrate” is formed in various shapes such as a circle and a rectangle.

  The substrate may be, for example, a substrate in which a metal region is formed on a bonding surface, or a bare glass or bare Si substrate in which a metal region or the like is not provided on the bonding surface. When a pair of substrates having metal regions on the bonding surfaces are bonded by bonding, for example, the metal region of one substrate and the metal region of the other substrate are formed so as to have a corresponding positional relationship. Has been. By joining the metal regions of both substrates, electrical connection is established between the substrates, and a predetermined mechanical strength is obtained. Further, the bonding surface may include a metal region that does not contribute to bonding, or may include a metal region that is bonded to a non-metal region of another substrate.

  The “substrate” also includes an assembly in which a plurality of chips are two-dimensionally arranged, for example, a substrate diced from a wafer and arranged on an adhesive sheet. Furthermore, the “substrate” also includes a structure including a chip formed by bonding one chip or a plurality of layers of chips and the substrate. Here, the “chip” is given as a broad concept term indicating a molded semiconductor plate-like component including a semiconductor component, an electronic component such as a packaged semiconductor integrated circuit (IC), and the like. The “chip” includes a component generally called a “die”, a component having a size smaller than that of the substrate, and a size that allows a plurality of components to be bonded to the substrate, or a small substrate. In addition to electronic components, optical components, optoelectronic components, and mechanical components are also included in the “chip”.

  FIG. 1 is a front view showing a configuration of a substrate bonding apparatus 100 according to an embodiment of the present invention. FIG. 1 shows a schematic structure inside the substrate bonding apparatus 100. In the following drawings, directions and the like are shown using an XYZ orthogonal coordinate system for convenience. For convenience, the Z direction is also referred to as the vertical direction, but the Z direction does not necessarily coincide with the vertical direction.

  The substrate bonding apparatus 100 includes a vacuum chamber 200, a substrate support unit 400, a position measurement unit 500, a surface treatment unit 600, and a controller 700. The substrate support unit 400 supports the substrates 301 and 302 that are the objects to be bonded to each other, and performs relative positioning of the substrates 301 and 302. The position measurement unit 500 measures the relative positional relationship between the substrates 301 and 302. The surface treatment unit 600 performs surface treatment on the surfaces of the substrates 301 and 302 that are supported to face each other in the Z direction. Hereinafter, the substrates 301 and 302 are also referred to as a “first substrate 301” and a “second substrate 302”, respectively. In FIG. 1, the first substrate 301 is disposed below the (−Z) side of the second substrate 302, but the first substrate 301 may be disposed above (the (+ Z) side) of the second substrate 302. Good. The controller 700 is a computer that is connected to each of the above-described components, and that is equipped with a program so as to receive information from these components, calculate, and issue a command to each component.

  The vacuum chamber 200 accommodates later-described stages 401 and 402 of the substrate support unit 400 and the surface treatment unit 600. Further, the vacuum chamber 200 includes a vacuum pump 201 as a evacuation unit for evacuating the inside. The vacuum pump 201 is configured to discharge the gas in the vacuum chamber 200 to the outside through the exhaust pipe 202 and the exhaust valve 203.

  The pressure in the vacuum chamber 200 is reduced (depressurized) in accordance with the suction operation of the vacuum pump 201, whereby the atmosphere in the vacuum chamber 200 is brought into a vacuum or a low pressure state. Further, the exhaust valve 203 can control and adjust the degree of vacuum in the vacuum chamber 200 by the opening / closing operation and the exhaust flow rate adjusting operation.

The vacuum pump 201 has a capability of reducing the atmospheric pressure in the vacuum chamber 200 to 1 Pa (Pascal) or less. It is preferable that the vacuum pump 201 has a capability of setting the background pressure before the surface treatment unit 600 described below operates to 1 × 10 ⁻² Pa (pascal) or less. The vacuum pump 201 reduces the pressure to 1 × 10 ⁻⁵ Pa (pascal) or less when a later-described line-type particle beam source 601 of the surface processing unit 600 emits particles (energy particles) having a kinetic energy of 1 eV to 2 keV. It is preferable to have the ability to

  This reduces the amount of impurities present in the atmosphere during the surface activation processing of the substrates 301 and 302 by the line type particle beam source 601, and after the surface activation processing, unnecessary oxidation of the new surface and new surface are performed. Impurities can be prevented from adhering to the surface. Furthermore, since the line type particle beam source 601 can apply a relatively high acceleration voltage, a high kinetic energy can be imparted to the particles at a relatively high degree of vacuum. Therefore, it is considered that the surface layer can be efficiently removed and the nascent surface can be made amorphous to activate the surfaces of the substrates 301 and 302.

  By pulling a relatively high vacuum by the operation of the vacuum pump 201, the substance removed from the surface layer of the substrate surface by the irradiation of the particle beam is efficiently exhausted out of the atmosphere (vacuum chamber 200). That is, undesired substances that re-attach and contaminate the exposed new surface are efficiently exhausted out of the atmosphere.

  The substrate support unit 400 includes stages 401 and 402 that support the substrates 301 and 302, stage moving mechanisms 403 and 404 that move the respective stages, and a pressure sensor that measures pressure when the substrates are pressed in the Z-axis direction. 408, 411 and a substrate temperature adjusting unit 420 for heating or cooling the substrate. The stage moving mechanisms 403 and 404 are substrate moving mechanisms that move the substrates 301 and 302. The second stage moving mechanism 404 includes an XY direction translation moving mechanism 405, a Z direction raising / lowering moving mechanism 406, and a Z axis rotation moving mechanism 407.

  The substrates 301 and 302 are attached to the support surfaces of the stages 401 and 402. The stages 401 and 402 have a holding mechanism such as a mechanical chuck or an electrostatic chuck so that the substrate can be fixed and held on the support surface, or the substrate can be removed by opening the holding mechanism. It is configured. Hereinafter, the stages 401 and 402 are also referred to as “first stage 401” and “second stage 402”, respectively.

  In FIG. 1, the lower first stage 401 is connected to a sliding first stage moving mechanism 403. Accordingly, the first stage 401 can translate in the X direction with respect to the vacuum chamber 200 or the upper second stage 402.

  In FIG. 1, the upper second stage 402 is connected to an XY direction translation mechanism 405, which is also called an alignment table. With the alignment table 405, the second stage 402 can be translated in the XY direction with respect to the vacuum chamber 200 or the lower first stage 401.

  The Z-direction lifting / lowering moving mechanism 406 is connected to the alignment table 405. The second stage 402 is configured to move in the vertical direction (Z direction) by the Z-direction lifting / lowering mechanism 406 so that the Z-direction interval between the stages 401 and 402 can be changed or adjusted. Yes. Moreover, both the stages 401 and 402 can make the pressurization after contact the contact surfaces which the board | substrates 301 and 302 to hold | maintain contact.

  A Z-axis pressure sensor 408 that measures the force related to the Z-axis is disposed in the Z-direction lifting and moving mechanism 406, thereby measuring the force related to the direction perpendicular to the joint surface that is in contact under pressure, and the joint surface Can be calculated. For the Z-axis pressure sensor 408, for example, a load cell may be used.

  Between the alignment table 405 and the second stage 402, three stage pressure sensors 411 and a piezo actuator 412 in the Z-axis direction at each stage pressure sensor 411 are provided. Each set of the stage pressure sensor 411 and the piezo actuator 412 is arranged at three different positions on the same line on the substrate support surface of the second stage 402. More specifically, each set including the three stage pressure sensors 411 and the three piezoelectric actuators 412 is arranged at substantially equal angular intervals in the vicinity of the outer peripheral portion in the substantially circular upper surface of the substantially cylindrical second stage 402. Has been placed.

  The three stage pressure sensors 411 connect the upper end surfaces of the corresponding piezoelectric actuators 412 and the lower surface of the alignment table 405. As a result, the force applied to the bonding surface of the substrate or the pressure distribution can be measured by the stage pressure sensor 411. Then, the force or pressure distribution is finely or accurately adjusted by extending or contracting the piezoelectric actuator 412 in the Z direction independently of each other, or the force or pressure applied to the bonding surface of the substrate is applied to the bonding surface. It can be controlled to be uniform or have a predetermined distribution.

  The Z axis rotation moving mechanism 407 can rotate the second stage 402 around the Z axis. The relative rotational position θ around the Z axis with respect to the first stage 401 of the second stage 402 is controlled by the rotational movement mechanism 407 around the Z axis, and the relative position in the rotational direction of both substrates 301 and 302 is controlled. Can do.

  The substrate bonding apparatus 100 includes a window 503, a light source (not shown), and a plurality of cameras 501 and 502 as a position measuring unit 500 for measuring the relative positional relationship between the substrates 301 and 302. The window 503 is provided in the vacuum chamber 200. The plurality of cameras 501 and 502 include light that is emitted from a light source and passes through a portion (not shown) provided with marks on both substrates 301 and 302 and the window 503, and propagates to the outside of the vacuum chamber 200. To capture the shadows.

  The position measurement unit 500 includes mirrors 504 and 505 that refract light propagating in the Z direction in the XY plane direction, and the cameras 501 and 502 are arranged to image light refracted in the Y direction. With this configuration, the size of the device in the Z-axis direction can be reduced.

  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 first stage 401, or may be provided so as to emit light traveling on the optical axis from the cameras 501 and 502 side. 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 of the substrates 301 and 302 are attached and portions where the light such as both stages should pass. If it is, infrared light) is used.

  The substrate bonding apparatus 100 uses the position measuring unit 500, stage moving mechanisms 403 and 404 for positioning the stage, and a controller 700 connected thereto, in the horizontal direction (X and Y directions) and the Z axis. The position (absolute position) of each of the substrates 301 and 302 in the vacuum chamber 200 or the relative position between the substrates 301 and 302 can be measured and controlled with respect to the surrounding rotation direction (θ direction). It is configured.

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

  Preferably, corresponding marks are attached to corresponding portions of the substrates 301 and 302, for example, positions overlapping in the Z direction during bonding. Both marks on the substrates 301 and 302 are observed within the same field of view, and their relative deviations (Δx, Δy) are measured. By measuring the relative deviations (Δx, Δy) at a plurality of locations, the relative positions (ΔX, ΔY, Δθ) between the substrates 301 and 302 can be calculated.

  Based on the relative position (ΔX, ΔY, Δθ) between the substrates 301, 302, an instruction is issued from the controller 700, and the substrate is moved to the moving mechanism of each stage 401, 402 by (−ΔX, −ΔY, −Δθ). Move.

  In order to accurately measure the relative positions of the substrates 301 and 302, they may be approached or brought into contact with each other. In this case, the substrates 301 and 302 may be separated when the stages 401 and 402 are moved. The relative position measurement and positioning operation of the substrates 301 and 302 may be repeated a plurality of times.

  The stages 401 and 402 in FIG. 1 incorporate heating and cooling units 421 and 422 as the substrate temperature adjusting unit 420, respectively. The heating / cooling units 421 and 422 are modules including, for example, a heater and a Peltier element. The heating and cooling units 421 and 422 heat or cool the substrates 301 and 302 supported by the stages 401 and 402 via the stages 401 and 402, respectively. That is, the substrate temperature adjusting unit 420 functions as a substrate heating unit and also functions as a substrate cooling unit. By controlling the heating and cooling units 421 and 422, the temperature of the substrates 301 and 302 and the temperature of the bonding surface of the substrates 301 and 302 can be adjusted and controlled.

  The surface treatment unit 600 includes a surface activation treatment unit 610 and a hydrophilization treatment unit 620. As the surface activation processing unit 610, for example, a particle beam source such as ions or neutral atoms, or a plasma source can be employed. As a result, a phenomenon (spattering phenomenon) in which a substance that forms the bonding surface of the substrates 301 and 302 is physically blown off is generated, and the surface layer can be removed.

  In the surface activation treatment, not only the surface layer is removed to expose the nascent surface of the substance to be joined, but also the crystal structure near the exposed nascent surface is made by colliding particles having a predetermined kinetic energy. It is thought that there is also an effect of disturbing and amorphizing. Since the amorphized nascent surface has a higher surface area at the atomic level and 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. In addition, in the case of chemically hydrophilizing treatment after the surface impurity removal step by the conventional wet treatment, there is no physical change of the nascent surface due to the collision of particles having a predetermined kinetic energy. The hydrophilic treatment following the activation treatment is considered to be fundamentally different from the conventional hydrophilic treatment in this respect.

  Here, the “amorphized surface” or “surface with disordered crystal structure” 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 that is assumed when the particle irradiation time is set relatively long or when the particle kinetic energy is set relatively high. It also includes a surface in which the presence of an amorphous layer or a surface with a disordered crystal structure is not confirmed by measurement using. Further, “amorphize” or “disturb the crystal structure” conceptually represents an operation for forming the above-described amorphized surface or a surface in which the crystal structure is disturbed.

  As 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 new surface with an oxide thin film after removing the surface layer. It is believed that the oxide thin film on the nascent surface increases the efficiency of hydroxyl (OH) group bonding or water deposition in subsequent hydrophilization treatments.

  It is preferable that the kinetic energy of the particles colliding with the surface to be surface activated is 1 eV to 2 keV. It is considered that the above kinetic energy efficiently causes the 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 particle | grain by accelerating the particle made to collide with the joint surface surface-activated toward a joint surface.

  FIG. 2 is a perspective view of the surface activation processing unit 610. In the example illustrated in FIGS. 1 and 2, the surface activation processing unit 610 includes a line type particle beam source 601, a shielding member 602, and a beam source moving mechanism 603. The beam source moving mechanism 603 moves the line-type particle beam source 601 and the shielding member 602 substantially in parallel to the bonding surfaces of the substrates 301 and 302 (that is, the target surface that is the target of the surface activation process). The beam source moving mechanism 603 inserts the line-type particle beam source 601 and the shielding member 602 into the space between the substrates 301 and 302, and retracts from the space. Further, the beam source moving mechanism 603 swings the line-type particle beam source 601 and the shielding member 602 around the line direction (X direction) of the line-type particle beam source 601 and the like.

  As shown in FIG. 2, the line particle beam source 601 is arranged so that the line direction or the longitudinal direction is parallel to the X direction. The line-type particle beam source 601 gives predetermined kinetic energy to particles that are neutral atoms, and radiates the particles toward the bonding surfaces of the substrates 301 and 302. The shielding member 602 is formed in a rectangular plate shape, and is arranged so as to be parallel to the line direction of the line-type particle beam source 601 and parallel to the X direction. The length in the longitudinal direction of the shielding member 602 is substantially the same as the length in the longitudinal direction of the line type particle beam source 601.

  The line-type particle beam source 601 and the shielding member 602 are translated by the beam source moving mechanism 603 in the Y direction, which is substantially perpendicular to the longitudinal direction of the both, while keeping the distance in the Y direction constant. In order to keep the distance in the Y direction between the line type particle beam source 601 and the shielding member 602 constant, the line type particle beam source 601 and the shielding member 602 may be connected by a mechanical member. Further, the distance in the Y direction may be kept constant by moving the line particle beam source 601 and the shielding member 602 at the same speed.

  A plurality of linear guides 604, 605, and 606 stretched in the Y direction translate the desired distance in the Y direction while supporting both ends of the linear particle beam source 601 and the shielding member 602 in the longitudinal direction, or , Can be positioned at a desired position.

  The linear guide 604 supports one end of each of the line-type particle beam source 601 and the shielding member 602 so as to be movable in the Y direction. The linear guide 604 includes a screw 604a extending in the Y direction, a nut 604b that moves by the longitudinal rotation of the screw 604a, and a servo motor 604c that rotates the screw 604a. The nut 604b supports the line-type particle beam source 601 and the shielding member 602 so as to be rotatable around respective rotation axes in the X direction and fixed in the XYZ directions. In FIG. 2, the nut 604 b also has a function of keeping the distance or distance in the Y direction between the line type particle beam source 601 and the shielding member 602 constant.

  The linear guides 605 and 606 are arranged parallel to each other in the Z direction, and respectively support the other ends of the line type particle beam source 601 and the shielding member 602 so as to be movable in the Y direction. Further, the linear guides 605 and 606 are rotary linear guides that can be rotated around the respective longitudinal axes, and the rotation is caused by the line direction (X of the line type particle beam source 601 and the shielding member 602). Direction) and a mechanism for transmitting the rotational motion around the rotational shafts 609a and 609b. Specifically, each of the rotary linear guides 605 and 606 includes rotary gears 607L and 608L that can move in parallel in the Y direction, and the rotary gear 607G and the shielding member 602 connected to the line type particle beam source 601 respectively. Is connected to a rotating gear 608G connected to The rotation gears 607L, 608L, 607G, and 608G are bevel gears, and can convert rotational motion between the meshing rotational gears into rotational motion around the vertical rotational axis and transmit the rotational motion. These gears use bevel gears, but are not limited thereto. For example, a worm gear may be adopted.

  In the surface activation processing unit 610, the rotary linear guides 605 and 606 are rotated or oscillated around the Y direction axis, and the rotation angle around the X direction axis between the line type particle beam source 601 and the shielding member 602 is determined. Oscillation can be controlled or set. The rotary linear guides 605 and 606 are individually connected to the line-type particle beam source 601 and the shielding member 602, respectively, and the rotation angles of the line-type particle beam source 601 and the shielding member 602 around the X-direction axis are set. It is configured so that it can be controlled or set independently.

  The line-type particle beam source 601 can translate the substrate 301 in the Y direction while emitting the particle beam B while maintaining a predetermined angle with respect to the bonding surface of the substrate 301 around the rotation axis 609a. . At a certain time, the line-type particle beam source 601 irradiates the band-shaped beam irradiation region R extending in the X direction on the substrate 301 with the particle beam B. As the translational movement in the Y direction occurs, the irradiation region R becomes the substrate. The bonding surface 301 is scanned.

  The shielding member 602 is disposed with the predetermined distance in the Y direction from the line type particle beam source 601. The shielding member 602 keeps a predetermined angle with respect to the bonding surface of the substrate 301 around the rotation axis 609b so as to shield the sputtered particles scattered from the substrate 301 by the beam irradiation of the line-type particle beam source 601 while maintaining a predetermined angle with respect to the bonding surface of the substrate 301 It translates along with the particle beam source 601 in the Y direction.

  By scanning at a constant speed while keeping the radiation condition of the particle beam B constant, the particle beam irradiation can be performed on the entire bonding surface of the substrate 301 under a very uniform condition. The irradiation amount per unit area of the particle beam B on the substrate can also be adjusted by the scanning speed of the particle beam source 601 with respect to the substrate 301.

  As described above, the line particle beam source 601 and the shielding member 602 are configured to be rotatable around the rotation axes 609a and 609b, respectively. Therefore, as shown in FIGS. 3A and 3B, after performing the irradiation scan of the particle beam B on the first substrate 301 (FIG. 3A), the same process as the substrate 301 is performed on the second substrate 302 as well. Can be performed (FIG. 3B).

  According to each of the case where the irradiation scan of the particle beam B is performed on the first substrate 301 (FIG. 3A) and the case where the irradiation scan of the particle beam B is performed on the second substrate 302 (FIG. 3B). The direction of the member 602 and the line type particle beam source 601 can be set to a predetermined direction.

  As shown in FIG. 3A, when the irradiation scan of the particle beam B is performed on the first substrate 301, the shielding surface 611 of the shielding member 602 is substantially directed toward the first substrate 301, and the line particle beam source 601 is used. Sputtered particles P scattered from the first substrate 301 due to sputtering by particle beam irradiation are blocked by the shielding surface 611. Thereby, it is possible to prevent the sputtered particles P from the first substrate 301 from adhering to the second substrate 302, which is the other substrate disposed oppositely, or to suppress the adhering amount to a minimum. .

  The line-type particle beam source 601 and the shielding member 602 are scanned on the first substrate 301 while being maintained in the above-described direction. As a result, the beam irradiation region R <b> 1 scans the first substrate 301, and the beam irradiation can be performed uniformly over the entire first bonding surface that is the bonding surface of the first substrate 301.

  In the substrate bonding apparatus 100, as shown in FIG. 3A, particle beam irradiation onto the first substrate 301 can be scanned while avoiding or minimizing the adhesion of sputtered particles P to the second substrate 302. Therefore, the particle beam irradiation to the second substrate 302 can be performed almost ideally thereafter. That is, if sputtered particles P adhere to the second substrate 302 during the particle beam irradiation on the first substrate 301, the irradiation time of the particle beam B compared to the processing of only the second substrate 302 in order to remove it. Needs to be set longer. Alternatively, in the case where an undesirable impurity is attached on the second substrate 302, the impurity may sink into the second substrate 302 or be mixed (mixed) due to the collision of atoms caused by particle beam irradiation. It may be necessary to modify the vicinity of the surface of the two substrates 302. In the substrate bonding apparatus 100, such a problem can be avoided or suppressed to a minimum.

  In the substrate bonding apparatus 100, as shown in FIG. 3B, when the particle beam irradiation is performed on the beam irradiation region R2 of the second substrate 302, the sputtered particles P scattered from the second substrate 302 are blocked by the shielding surface of the shielding member 602. 611 to block. Therefore, adhesion of the sputtered particles P to the region R1 of the first substrate 301 that has completed the particle beam irradiation can be avoided or suppressed. In other words, sputtered particles scattered from the second substrate 302 while scanning and executing particle beam irradiation on the second bonding surface, which is the bonding surface of the second substrate 302, with respect to the second substrate 302. It is possible to prevent P from adhering to the first substrate 301 by shielding P. Thereby, the predetermined property of the region R1 of the first substrate 301 obtained by the particle beam irradiation can be maintained. Specifically, the activity of the bonding surface of the first substrate 301 once surface-activated by particle beam irradiation can be maintained during the surface activation process of the bonding surface of the second substrate 302. Therefore, even if the substrate surface is activated alternately, it is possible to form a solid-phase bonding interface with high bonding strength and less impurity contamination.

The line-type particle beam source 601 operates in a relatively high vacuum, such as 1 × 10 ⁻⁵ Pa (pascal) or less, so that after the surface activation treatment, unnecessary oxidation of the nascent surface and adhesion of impurities to the nascent surface are performed. Etc. can be prevented. Furthermore, since the line type particle beam source 601 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.

  As shown in FIGS. 3A and 3B, the line-type particle beam source 601 and the plate-shaped shielding member 602 are rotatable around a rotation axis parallel to the X direction, and may be disposed close to each other. For example, when only the line-type particle beam source 601 is rotated toward the second substrate 302 after the beam irradiation to the first substrate 301 is finished in a state where the plate-like shielding member 602 is parallel to the substrate surface, The particle beam source 601 may be disposed as close as possible to collide with or come into contact with the shielding member 602. In such a case, the shielding member 602 is rotated so that the side of the shielding member 602 on the line type particle beam source 601 side approaches the first substrate 301 side, and then the line type particle beam source 601 is moved to the second substrate. Rotate toward 302. Accordingly, the attitude of the line-type particle beam source 601 can be changed so as to face the second substrate 302 without contacting the shielding member 602. Thereafter, the shielding member 602 can be rotated and positioned at a position parallel to the bonding surface of the substrates 301 and 302 for beam irradiation onto the second substrate 302.

  In FIG. 3B, the line-type particle beam source 601 moves from the left to the right (+ Y direction) in the drawing with respect to the second substrate 302, but the particles move while moving from the right to the left (−Y direction). Beam irradiation may be performed. The line-type particle beam source 601 and the shielding member 602 are moved from the left to the right with respect to the first substrate 301 to perform the particle beam irradiation, and the second substrate 302 is moved from the right to the left to perform the particle beam irradiation. You may go. Thereby, the moving distance of the line-type particle beam source 601 can be shortened compared to the case where the particle beam irradiation is performed by moving any substrate in the same direction (for example, from left to right in the figure). Process efficiency is improved.

  The distance between the line type particle beam source 601 and the shielding member 602 need not always be the same. For example, when the scattering direction of the sputtered particles is different between the first substrate 301 and the second substrate 302 due to a difference in the scanning direction, the interval may be changed. In other words, the shielding member 602 has a size, shape, or posture that efficiently shields the sputtered particles that are scattered under each condition of particle beam irradiation and prevents or minimizes reaching the other substrate. It only has to be configured.

  For example, the beam irradiation such as the angle formed on the substrate surface of the line-type particle beam source 601, the type and kinetic energy of the particle beam (energy particles), the material of the substrate surface, the surface shape and the crystal direction for each predetermined process or scan. Depending on the conditions, the scattering direction and scattering angle of the sputtered particles can change. Therefore, the angle and size of the shielding member 602, the position or posture of the line-type particle beam source 601, and the substrates 301 and 302, etc., so as to efficiently shield the scattered sputtered particles according to the predetermined beam irradiation conditions. The device may be configured so that it can be changed.

  The line particle beam source 601 and the shielding member 602 are configured to move between the substrates 301 and 302 in parallel to the bonding surface, but are not limited thereto. The apparatus is configured so that the line-type particle beam source 601 and the shielding member 602 appropriately move between the substrates 301 and 302 according to various cases such as when the substrates 301 and 302 are not two-dimensionally flat. May be.

  In the example shown in FIG. 2, the line-type particle beam source 601 and the shielding member 602 are disposed so that the longitudinal direction is substantially parallel to the line direction (X direction), and substantially perpendicular to the line direction (X direction) (Y It is configured to translate in the direction), but is not limited to this. The longitudinal direction of the line type particle beam source 601 or the like may not be perpendicular (90 degrees) to the translational movement direction. For example, the apparatus is configured to form a predetermined angle (60 degrees, 45 degrees). Also good. The apparatus may be configured such that the predetermined angle is variable for each scan.

  In the example shown in FIG. 3A and FIG. 3B, the surface activation processing unit 610 is configured so that beam irradiation can be performed on both the substrates 301 and 302 by a single line type particle beam source 601. Not limited. For example, the surface activation processing unit 610 may include a plurality of line type particle beam sources 601.

  For example, a line type particle beam source 601 shown in FIGS. 4A and 4B includes a first line type particle beam source 6011 and a second line type particle beam source 6012, and is arranged between two opposing substrates 301 and 302. Is done. The first line type particle beam source 6011 performs beam irradiation on the first substrate 301, and the second line type particle beam source 6012 performs beam irradiation on the second substrate 302.

  In this case, the shielding member 602 is disposed between the substrates 301 and 302 and shields the sputtered particles P scattered from both the substrates 301 and 302. That is, the surface 6021 of the shielding member 602 facing the first substrate 301 is changed from the first substrate 301 to the second substrate 302 by beam irradiation of the first substrate line type particle beam source (first line type particle beam source) 6011. The sputtered particles P scattered toward the screen are shielded so that the sputtered particles P are prevented from adhering to the second substrate 302 or minimized. On the other hand, the surface 6022 of the shielding member 602 facing the second substrate 302 is irradiated from the second substrate line type particle beam source (second line type particle beam source) 6012 from the second substrate 302 to the first substrate 301. The sputtered particles P scattered toward the screen are shielded so that the sputtered particles P are prevented from adhering to the first substrate 301 or minimized.

  The shielding member 602 is formed in a substantially plate shape. When the opposing surfaces of both the substrates 301 and 302 are parallel, the plate-shaped shielding member 602 is disposed so that its main surface is parallel to the surfaces of both the substrates 301 and 302. With this configuration, an efficient substrate surface treatment can be performed, and the substrate surface treatment apparatus can be made small.

  While the line-type particle beam sources 6011 and 6012 are operated to irradiate the substrates 301 and 302 with the particle beam, both the line-type particle beam sources 6011 and 6012 and the shielding member 602 are placed in the Y direction or a direction parallel to the substrate surface. By performing translational movement, the particle beam irradiation process for both substrates 301 and 302 can be performed in the same scan. Therefore, an efficient and clean surface activation treatment is possible.

  When two opposing substrates 301 and 302 are arranged in parallel, as shown in FIG. 4A and FIG. 4B, both lines are mirror-symmetric with respect to the symmetry center plane of both substrates 301 and 302. Preferably, the particle beam sources 6011 and 6012 and the shielding member 602 are arranged. With this configuration, the two-line particle beam sources 6011 and 6012 and the shielding member 602 can be scanned with respect to the substrates 301 and 302 at the same speed, or while maintaining the relative positional relationship between them. it can. Thereby, it is possible to simultaneously irradiate both the substrates 301 and 302 and simultaneously shield the sputtered particles P scattered from the respective substrates 301 and 302 by the beam irradiation. Therefore, it is possible to perform a clean surface activation process on both the substrates 301 and 302 at the same time and extremely efficiently.

  In the configuration shown in FIG. 4A, the first substrate line type particle beam source 6011 and the second substrate line type particle beam source 6012 are arranged on the traveling direction side with respect to the shielding member 602, and the directions are reversed from the Y direction. It is arranged in a state tilted by almost the same angle. The line particle beam sources 6011 and 6012 for both substrates can perform beam irradiation on the beam irradiation regions R1 and R2 at substantially the same Y-direction positions on the substrates 301 and 302, respectively. The plate-shaped shielding member 602 has an appropriate shape, and is disposed at an appropriate Y-direction position with respect to the line type particle beam sources 6011 and 6012 for both substrates, so that the spatter scattered from both the substrates 301 and 302 is obtained. The particles P can be shielded.

  Although not shown, the first substrate line type particle beam source 6011 and the second substrate line type particle beam source 6012 are both arranged on the opposite side of the traveling direction with respect to the shielding member 602. Also good.

  In the configuration shown in FIG. 4B, the first substrate line type particle beam source 6011 and the second substrate line type particle beam source 6012 are respectively in the traveling direction side and the opposite side of the traveling direction with respect to the shielding member 602. Has been placed. In this case, the line particle beam sources 6011 and 6012 for both substrates are arranged substantially rotationally symmetrically about the longitudinal axis of the shielding member 602. The shielding member 602 is positioned substantially at the center of the line type particle beam sources 6011 and 6012 for both substrates, and can shield the sputtered particles P scattered from both the substrates 301 and 302 by having an appropriate shape. .

  As the line type particle beam source 601, for example, a fast atom beam (FAB) can be used. A fast atomic beam source (FAB) typically generates a rare gas plasma, applies an electric field to the plasma, extracts particles ionized from the plasma, and passes them through an electron cloud. It has the structure which becomes sexual. For example, when argon (Ar) is used as a rare gas, the power supplied to the fast atomic 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 atomic beam source (FAB) is operated at 100 W (watts) to 200 W (watts) and irradiated with a fast atomic beam of argon (Ar) for about 2 minutes, the oxide, contaminants, etc. (surface) Layer) can be removed to expose the nascent surface.

  As the line-type particle beam source 601, for example, an ion beam source (ion gun) that emits particles that are ions toward the bonding surfaces of the substrates 301 and 302 may be used. The ion beam source may be used, for example, operated at 110V and 3A, and accelerated argon (Ar) to irradiate the bonding surfaces of the substrates 301 and 302 for about 600 seconds. As other conditions, an acceleration voltage of 1.5 kV to 2.5 kV and a current of 350 mA to 400 mA may be adopted, and as another condition, an acceleration voltage of 1.0 kV to 2.0 kV and a current of 300 mA to 500 mA are adopted. May be. As the ion beam source, a cold cathode type, a hot cathode type, a PIG (Penning Ionization Gauge) type, an ECR (Electron Cyclotron Resonance) type particle beam source, a cluster ion source, or the like can be adopted.

  By irradiating the bonding surface of the substrate with a particle beam from the line type particle beam source 601, surface activation treatment can be performed. By the surface activation treatment, the bonding surfaces of the substrates can be solid-phase bonded at room temperature or without heating.

As other beam irradiation conditions by the line-type particle beam source 601, a background pressure in the vacuum chamber 200 is set to 10 ⁻⁶ Pa (Pascal), Ar is supplied as a gas at a flow rate of 100 sccm, and the pressure in the vacuum chamber 200 is set. Can be set to 10 ⁻³ Pa (pascal) or less, the line-type particle beam source 601 is operated at 2 kV and 20 mA, and the scanning speed of the line-type particle beam source 601 with respect to the substrates 301 and 302 can be set to 10 mm / s. Each of the beam irradiation conditions described above is for illustrative purposes and is not limited thereto. The beam irradiation conditions can be appropriately changed according to the configuration of each apparatus, the beam irradiation conditions, the physical properties of the processing target such as the substrate, and the like.

  In the surface activation processing unit 610, a predetermined kinetic energy can be given to the particles using a plasma generator. In this case, by applying an alternating voltage to the bonding surfaces of the substrates 301 and 302, plasma containing particles is generated around the bonding surfaces. Then, by accelerating the cations of the ionized particles in the plasma toward the bonding surface by the voltage, predetermined kinetic energy is given to the particles. The plasma can be generated in a low vacuum atmosphere of about several Pa (Pascal). For this reason, while being able to simplify a vacuum system, processes, such as evacuation, can be shortened.

  The above-described plasma generator may be used, for example, to operate at 100 W to generate argon (Ar) plasma and irradiate the bonding surfaces of the substrates 301 and 302 with the plasma for about 600 seconds.

  In the surface activation processing unit 610, the particles used for the surface activation may be radical species in addition to neutral atoms and ions, or may be a particle group in which these are mixed. In addition to an inert gas such as argon (Ar), for example, nitrogen, oxygen, or water may be used as the particle beam as the particle beam.

  In the substrate bonding apparatus 100 shown in FIG. 1, when the surface activation processing of the substrates 301 and 302 by the surface activation processing unit 610 is completed, the hydrophilic processing by the hydrophilic processing unit 620 is performed. Thereby, it is considered that a hydroxyl group (OH group) is bonded to the bonded surfaces of the cleaned or activated substrates 301 and 302. Furthermore, water molecules adhere to the bonding surface to which the hydroxyl group (OH group) is bonded.

The hydrophilization treatment of the substrates 301 and 302 is performed by supplying water to the surface activated bonding surfaces. The water can be supplied by introducing water (H ₂ O) into the atmosphere around the surface activated bonding surface. Water may be introduced in a gaseous state (in a gaseous state or as water vapor) or in a liquid state (a mist state). Furthermore, radicals, ionized OH, or the like may be attached as another aspect of the hydrophilic treatment for the joint surface. The method of hydrophilizing the bonding surface is not limited to these.

In the hydrophilization processing unit 620, for example, by passing a carrier gas such as nitrogen (N ₂ ), argon (Ar), helium (He), oxygen (O ₂ ) in liquid water (bubbling), It is preferable that gaseous water is mixed with the carrier gas and introduced into the vacuum chamber 200 in which the substrates 301 and 302 having the surface-activated bonding surfaces are arranged.

In the example illustrated in FIG. 1, the hydrophilization processing unit 620 includes a gas supply source 621, a flow rate control valve 622, and a gas introduction unit 623. The gas supply source 621 supplies a mixed gas (that is, a gas containing water molecules) of the carrier gas and water (H ₂ O) generated by the above bubbling into the vacuum chamber 200 through the gas introduction unit 623. Supply. The flow rate control valve 622 controls the flow rate of the mixed gas supplied from the gas supply source 621 to the vacuum chamber 200.

  In the substrate bonding apparatus 100, the hydrophilic treatment process can be controlled by controlling the humidity of the atmosphere around the surface activated bonding surface. The humidity may be calculated as relative humidity, may be calculated as absolute humidity, or other definitions may be employed.

  The humidity in the vacuum chamber 200 is controlled by the humidity of the mixed gas generated by the gas supply source 621, the amount of the mixed gas controlled by the flow rate control valve 622 introduced into the vacuum chamber 200, and the inside of the vacuum chamber 200 by the vacuum pump 201. This can be done by adjusting the gas discharge amount, the temperature in the vacuum chamber 200, and the like. The humidity in the vacuum chamber 200 is preferably controlled so that the relative humidity in the atmosphere around at least one or both of the bonding surfaces of the substrates 301 and 302 is 10% or more and 90% or less.

  The hydrophilization processing unit 620 may further include the above-described substrate temperature adjusting unit 420 that cools the substrates 301 and 302. By cooling the bonding surfaces of the substrates 301 and 302 by the substrate temperature adjusting unit 420, the relative humidity in the atmosphere around the bonding surfaces of the substrates 301 and 302 can be easily increased. Thereby, the supply_amount | feed_rate of the water with respect to a joint surface can be increased easily.

In the hydrophilization processing unit 620, for example, when gaseous water is introduced using nitrogen (N ₂ ) or oxygen (O ₂ ) as a carrier gas, the total pressure in the vacuum chamber 200 is set to 9.0 × 10 ⁴ Pa (pascal), That is, the amount of gaseous water in the vacuum chamber 200 is set to 0.89 atm (Atom), and the volume absolute humidity is 8.6 g / m ³ (gram / cubic meter) or 18.5 g / m ³ (gram / cubic meter). And a relative humidity of 23 ° C. (23 degrees Celsius) can be controlled to be 43% or 91%, respectively. Further, the atmospheric concentration of oxygen (O ₂ ) in the chamber may be 10%.

  In the hydrophilic treatment unit 620, the atmosphere outside the vacuum chamber 200 having a predetermined humidity may be introduced into the vacuum chamber 200 in order to perform the hydrophilic treatment. When the atmosphere is introduced into the vacuum chamber 200, it is preferable that the atmosphere pass through a predetermined filter in order to prevent unwanted impurities from adhering to the bonding surface. By introducing the atmosphere outside the vacuum chamber 200 having a predetermined humidity to perform the hydrophilic treatment, the configuration of the apparatus for performing the hydrophilic treatment on the joint surface can be simplified.

Further, in the hydrophilization processing unit 620, water (H ₂ O) molecules, clusters, and the like may be accelerated and emitted toward the bonding surfaces of the substrates 301 and 302. For acceleration of water (H ₂ O), a line type particle beam source 601 used for the surface activation treatment may be used. In this case, a mixed gas of carrier gas and water (H ₂ O) generated by the gas supply source 621 described above is introduced into the line-type particle beam source 601 and the like, thereby generating a water particle beam and hydrophilizing. Irradiation can be directed toward the joint surface to be treated. 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.

  As the hydrophilic treatment of the bonding surfaces of the substrates 301 and 302, water cleaning that also serves to remove particles (contaminated particles) from the substrates 301 and 302 may be performed after the surface activation treatment of the substrates 301 and 302. . By the water washing, the same effect as the above-described hydrophilic treatment can be obtained. The water cleaning may be performed, for example, by spraying a water flow provided with ultrasonic waves toward the bonding surfaces of the substrates 301 and 302. The water cleaning is usually not performed in the vacuum chamber 200, but is performed outside the vacuum chamber 200 as described later.

  As the hydrophilic treatment of the bonding surfaces of the substrates 301 and 302, the same or different hydrophilic treatment may be performed a plurality of times. In addition, water molecules may be forcibly attached to the joint surface in parallel with the hydrophilic treatment or after the hydrophilic treatment. Thereby, the amount of water molecules on the joint surface can be increased or controlled. The adhesion of the water molecules may be performed, for example, by cooling the bonding surfaces of the substrates 301 and 302 by the substrate temperature adjusting unit 420. Alternatively, the attachment of the water molecules may be performed by washing the bonding surfaces of the substrates 301 and 302 described above with water.

  The completion time of the hydrophilic treatment may be determined by an experiment performed in advance, or it is confirmed that sufficient hydrophilic treatment has been performed by in-situ observation using a predetermined surface evaluation unit. May be determined.

  In the example shown in FIG. 1, the surface activation process and the hydrophilization process for the substrates 301 and 302 are continuously performed in one vacuum chamber 200. Therefore, the bonding surface of the substrates 301 and 302 subjected to the surface activation treatment can be subjected to hydrophilic treatment without exposing the bonding surfaces to the atmosphere. Thereby, undesirable oxidation of the bonding surfaces of the substrates 301 and 302 and adhesion of impurities or the like to the bonding surfaces can be prevented. Further, the hydrophilic treatment can be controlled more easily, and the hydrophilic treatment can be continued and efficiently executed after the surface activation treatment.

  FIG. 5 is a diagram illustrating a flow of bonding between the first substrate 301 and the second substrate 302. First, the surface activation process is performed on the first bonding surface of the first substrate 301, and the surface activation process is performed on the second bonding surface of the second substrate 302 (step S11). When the surface activation process is completed, a hydrophilization process is performed on the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 (step S12). As a result, a hydroxyl (OH) group is bonded to the bonding surfaces of the substrates 301 and 302.

  When the hydrophilic treatment is completed, water molecules are applied to the bonding surfaces of the substrates 301 and 302, and the water molecules adhere to the bonding surfaces (step S13). When water molecules adhere to the bonding surfaces of the substrates 301 and 302 in step S12, additional water molecules adhere to the bonding surfaces in step S13. The step of attaching water molecules in step S13 may be performed in parallel with the hydrophilic treatment in step S12. Step S13 can be regarded as part of the hydrophilization process of step S12.

  Subsequently, the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 are brought into contact with each other, and the substrates 301 and 302 are pressurized with a pressure equal to or lower than a critical pressure described later (that is, with a pressure equal to or lower than the critical pressure). By pressing the first substrate 301 and the second substrate 302 against each other), the first substrate 301 and the second substrate 302 are temporarily joined (step S14). In step S14, the substrates 301 and 302 are pressurized with a pressure of about 0.05 MPa, for example.

  The pressurization in step S14 may be started simultaneously with the contact between the first substrate 301 and the second substrate 302, or may be started after a predetermined time has passed since the contact. Further, the pressurization in step S14 may be performed over a part of the time during which the substrates 301 and 302 are in contact with each other, or may be performed over the whole. Furthermore, the pressurization in step S14 may be performed intermittently. During pressurization in step S14, even if a constant pressure is maintained, the pressure may change with time. Note that the pressing of the first substrate 301 and the second substrate 302 to each other in step S14 includes a load of several g (gram) and contact at the own weight level.

  6A to 6C are diagrams conceptually showing the state of the bonding surface of the substrate 301 in steps S12 to S14. The state of the bonding surface of the substrate 302 is the same as that shown in FIGS. 6A to 6C. As described above, hydroxyl (OH) groups are bonded to the bonding surfaces of the substrates 301 and 302, and water molecules are attached on the hydroxyl (OH) groups. In step S12, the hydroxyl (OH) group is bonded to the bonding surface by the interface between the substrates 301 and 302 made amorphous in step S11 by absorbing water molecules and promoting oxidation. At this time, since water molecules cannot sufficiently react, it is considered that the density of hydroxyl (OH) groups bonded to the bonding surface is not sufficiently high as shown in FIG. 6A. In other words, it is considered that a gap (enclosed by a two-dot chain line in FIG. 6A) is formed between the hydroxyl (OH) groups.

In step S14, as shown in FIG. 6B, some of the water molecules on the hydroxyl (OH) group are bonded to each other due to the close contact between the substrates 301 and 302 during temporary bonding, the pressure applied to the substrates 301 and 302, and the like. It penetrates into the gaps between the hydroxyl (OH) groups on the surface. The permeated water molecules are absorbed by the interfaces of the amorphous substrates 301 and 302 and used for oxidation, and are bonded to the bonding surfaces of the substrates 301 and 302 as hydroxyl (OH) groups. Thereby, as shown to FIG. 6C, the hydroxyl (OH) group on the joint surface of the board | substrates 301 and 302 increases. In step S <b> 14, the substrates 301 and 302 are temporarily bonded by hydrogen bonding between hydroxyl (OH) groups bonded to the bonding surfaces of the substrates 301 and 302. Bonding strength of the substrate 301, 302 to each other after the temporary bonding is, for example, about ^{0.2J / m 2 ~0.5J / m 2} .

  Next, the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 are separated from each other in a substantially vertical direction (Z direction) (step S15). Thereafter, the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 are brought into contact again, and the substrates 301 and 302 are pressed at a pressure higher than the critical pressure, whereby the first substrate 301 and the second substrate are pressed. 302 is joined (main joining) (step S16). In other words, the substrates 301 and 302 are finally joined by pressing the first substrate 301 and the second substrate 302 against each other at a pressure higher than the critical pressure. In step S <b> 16, the substrates 301 and 302 are bonded to such an extent that they cannot be easily separated by being pressurized with a pressure of about 5 MPa, for example.

  In step S16, after pressurizing the substrates 301 and 302 with the bonding surfaces in contact with each other at a pressure higher than the critical pressure, or in parallel with pressurizing at a pressure higher than the critical pressure, 302 may be heated. The substrates 301 and 302 are heated, for example, by conducting heat from the stages 401 and 402 shown in FIG. The heating of the substrates 301 and 302 may be performed, for example, by irradiating light to the bonding surfaces of the substrates 301 and 302.

7A to 7C are diagrams conceptually showing the state of the bonding surface when the substrates 301 and 302 are bonded in step S16. When the bonding surfaces of the substrates 301 and 302 to which a large number of hydroxyl (OH) groups are bonded as shown in FIG. 7A come into contact, as shown in FIG. 7B, hydrogen bonds between the hydroxyl (OH) groups are generated. Thereafter, due to the pressure and heat applied to the substrates 301 and 302, water (H ₂ O) is detached (ie, dehydrated) between the substrates 301 and 302 as shown in FIG. 7C, and hydrogen bonds are covalently bonded. By changing to, the bonding strength between the substrates 301 and 302 is improved. Step S16 After the end (i.e., after the bonding) bonding strength of the substrate 301, 302 with each other is, for example, about ^{1.0J / m 2 ~2.5J / m 2} .

  Steps S11 and S12 described above are performed in a relatively high vacuum. Steps S13 to S15 may be performed in a vacuum or in the atmosphere, for example. Step S16 is performed in a relatively high vacuum. The term “in a vacuum” as used herein includes not only the atmosphere but also a depressurized environment of any gas. Further, steps S14 and S15 may be repeated a plurality of times before step S16 is performed.

  In step S16, it is not always necessary to press the substrates 301 and 302 with a pressure larger than the critical pressure. For example, after pressurizing the substrates 301 and 302 with the bonding surfaces in contact with each other at a pressure equal to or lower than the critical pressure, or heating in parallel with pressurizing at a pressure equal to or lower than the critical pressure, 302 may be joined to such an extent that they cannot be easily separated. Alternatively, by heating the substrates 301 and 302 at a predetermined temperature without applying pressure, the substrates 301 and 302 may be bonded to such an extent that they cannot be easily separated from each other.

  The critical pressure may be defined as a pressure at which a desired characteristic of the joint surface changes or is lost when the joint surface is pressed at a pressure higher than that.

  For example, if too much pressure is applied to the bonding surfaces of the substrates 301 and 302 in the temporary bonding process (contact process) in step S14 before the final bonding interface is formed between the substrates 301 and 302 in step S16, both the substrates 301 and 301 are formed. , 302 cannot be separated due to bonding, or even if they can be separated, desired bonding may not be possible when they are contacted again and pressed. Therefore, if the pressure applied to the bonding surface in the temporary bonding process in step S14 is reduced, the substrates 301 and 302 that are in contact with each other can be separated without impairing the surface characteristics for performing desired bonding. Thus, the maximum pressure that can separate the substrates 301 and 302 after provisional bonding may be defined as the critical pressure.

  Alternatively, if the temporary bonding and separation of the substrates 301 and 302 are repeated a plurality of times, they can be separated, but the desired bonding strength can be obtained even if the bonding step of step S16 is performed thereafter by repeating temporary bonding or temporary bonding. Such a characteristic may not be obtained. For example, in the temporary bonding step of step S14, even if the newly formed surfaces are in contact with each other at a part of the contact interface, and a locally or microscopically strong bonded interface is formed, the substrate 301, It may be possible to separate the 302. However, even if the substrates 301 and 302 themselves can be separated, the surface characteristics of the substrates 301 and 302 are deteriorated due to the destruction of the strongly formed bonding interface due to the separation. In some cases, the bonding characteristics may not be finally obtained. In this case, it is possible to sufficiently avoid exposure and contact of the new surface by reducing the pressure applied to the joint surface in the temporary joining step. As described above, when the cause is that the pressure applied to the joining surfaces in the temporary joining step is substantially high, by reducing the pressure, even if the temporary joining and the separation are repeated a plurality of times, finally, A desired bonding strength can be obtained. In this way, the maximum pressure in the temporary joining step that can be separated and finally obtains a desired joining strength may be defined as the critical pressure.

  The critical pressure may be defined as a pressure at which a desired bonding cannot be performed when a higher pressure is applied to the substrates 301 and 302.

  The critical pressure can be determined according to various factors such as the material forming the bonding surface of the substrates 301 and 302, the presence or absence of a surface layer on the bonding 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 surfaces of the substrates 301 and 302 before step S11 in FIG.

  It is preferable that the pressure applied to the substrates 301 and 302 in the temporary bonding step in step S14 is equal to or lower than the smaller critical pressure of the critical pressures defined on the bonding surfaces of both the substrates 301 and 302. Thereby, an appropriate pressure can be reliably applied to any joint surface. When the critical pressure is not defined on the bonding surface of one substrate, a pressure lower than the critical pressure of the bonding surface of the other substrate on which the critical pressure is defined may be applied to the substrates 301 and 302.

  The critical pressure can change for each temporary joining step when the temporary joining step in step S14 and the separation step in step S15 are performed a plurality of times. Depending on the contact of the bonding surfaces of the substrates 301 and 302, the surface characteristics such as the presence or disappearance of a predetermined surface layer on the bonding surface, the fine surface shape, and the like can be changed depending on the pressurization condition at the time of contact and the condition of the bonding surface. Therefore, one temporary joining process can affect the critical pressure of the next temporary joining process. When Steps S14 and S15 are performed a plurality of times, the surface condition of the bonding surface of the substrates 301 and 302 is inspected every time Steps S14 and S15 are performed once, and the next Step S14 or Step S16 is performed based on the inspection result. A critical pressure may be defined or calculated.

  For example, when the bonding surfaces of the substrates 301 and 302 are covered with a predetermined surface layer, the surface characteristics may change due to partial destruction of the surface layer by the temporary bonding step. As an example of the change in the surface characteristics, the hydroxyl group (OH group) layer is partially destroyed by contact during temporary bonding on the bonding surfaces of the substrates 301 and 302 that have been subjected to hydrophilization treatment, and the new metal surfaces contact each other. Thus, it is conceivable to form a locally strong bonding interface.

  As another example, when an oxide film layer is formed on the bonding surface before the temporary bonding process, the oxide film layer is partially destroyed by the temporary bonding process, and the newly formed surfaces are in contact with each other. It is conceivable to form a locally strong bonding interface. Alternatively, when a hydroxyl group (OH group) is formed on the bonding surface before the temporary bonding step and water molecules exist on the bonding surface, the temporary bonding step drives the water molecules to contact each other or penetrates the hydroxyl layer. It is also conceivable that the newly formed surfaces come into contact with each other to form a locally strong bonding interface.

  In the above example, the bonding strength has a characteristic that affects the critical pressure, but is not limited thereto. For example, mechanical properties other than bonding strength may be used, or electrical or chemical properties may be used.

  As described above, the bonding strength between the substrates 301 and 302 can be improved by bonding the substrates 301 and 302 in steps S11 to S16. As described above, the bonding strength is improved by the pressure that water molecules attached on the bonding surfaces of the substrates 301 and 302 in the hydrophilic treatment in step S12 are applied to the substrates 301 and 302 in the temporary bonding process in step S14. This is considered to be due to an increase in the number of hydroxyl groups (OH groups) per unit surface area of the bonding surface by newly bonding to the bonding surface as a hydroxyl group (OH group) due to (ie, a pressure equal to or lower than the critical pressure). The increased hydroxyl group (OH group) is caused by the pressure applied to the substrates 301 and 302 (for example, a pressure larger than the critical pressure) and / or heat in the bonding process of step S16, and the substrates 301 and 302 are strengthened. It is considered that the state changes to a state that contributes to bonding.

  In addition, by bonding the substrates 301 and 302 in steps S11 to S16, voids between the substrates 301 and 302 can be reduced. Specifically, voids generated in the temporary bonding process or the like in step S14 are reduced by the separation process in step S15 and the re-bonding process in vacuum in step S16. Thereby, it is possible to provide a bonded substrate having high bonding strength and few voids.

  As described above, the adhesion of water molecules in step S13 is performed between step S12 and step S14 or in parallel with step S12, thereby reducing the amount of water molecules on the bonding surfaces of the substrates 301 and 302. Can be increased. Thereby, in the temporary joining process of step S14, the hydroxyl group (OH group) considered to couple | bond with a joining surface can be increased, As a result, the joint strength of board | substrates 301 and 302 can further be improved. Note that step S13 may be omitted when the bonding strength between the substrates 301 and 302 can be sufficiently secured.

  It is preferable that the temporary joining process of step S14 described above is performed in the atmosphere. Thereby, compared with the case where the temporary bonding process of step S14 is performed in vacuum, the bonding strength between the substrates 301 and 302 after the completion of step S16 can be further improved.

  Moreover, it is preferable that the separation process of step S15 is performed in a relatively high vacuum. Thereby, the joint strength between the substrates 301 and 302 after step S16 can be further improved. The reason why the bonding strength is further improved as compared with the case where step S15 is performed in the atmosphere is that the elapsed time from the separation of the substrates 301 and 302 in step S15 to the bonding of the substrates 301 and 302 in the vacuum in step S16 is shortened. This is thought to be due to

  When the above-described bonding of the substrates 301 and 302 (steps S11 to S16) is performed in the substrate bonding apparatus 100 illustrated in FIG. 1, first, the surface activation processing unit 610 performs the first substrate 301 bonding in the vacuum chamber 200. The first bonding surface and the second bonding surface of the second substrate 302 are activated (step S11). Specifically, the bonding surface of the first substrate 301 is activated by irradiating the bonding surface of the first substrate 301 with a particle beam from the line type particle beam source 601. Further, the bonding surface of the second substrate 302 is activated by irradiating the bonding surface of the second substrate 302 with a particle beam from the line type particle beam source 601.

Subsequently, the hydrophilic treatment section 620 performs a hydrophilic treatment on the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 (step S12). Specifically, a mixed gas of a carrier gas and water (H ₂ O) is supplied from a gas supply source 621 to the vacuum chamber 200, and in the vacuum chamber 200, the bonding surface of the first substrate 301 and the second substrate 302. Hydroxyl groups (OH groups) are bonded to the bonding surfaces, and the bonding surfaces of the substrates 301 and 302 are hydrophilized.

  In the substrate bonding apparatus 100, in parallel with step S12, the substrate temperature adjusting unit 420 cools the bonding surfaces of the substrates 301 and 302, thereby increasing the relative humidity in the atmosphere around the bonding surfaces. As a result, the amount of water supplied to the bonding surface increases, and water molecules adhere to the bonding surfaces of the substrates 301 and 302 (for example, on the hydroxyl layer on the bonding surface) (step S13). The attachment of water molecules to the joint surface in step S13 may be performed between step S12 and step S14. By cooling the bonding surfaces of the substrates 301 and 302 by the substrate temperature adjusting unit 420, water molecules can be easily attached on the bonding surfaces in step S13.

  Next, the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 are brought into contact with each other, and the substrates 301 and 302 are pressed with a pressure equal to or lower than the critical pressure, whereby the first substrate 301 and the second substrate 301 are pressed together. The substrate 302 is temporarily joined (step S14). During temporary bonding of the substrates 301 and 302, the relative positions of the substrates 301 and 302 are measured by the position measuring unit 500, and the substrate 301 is detected by the alignment table 405 of the first stage moving mechanism 403 and the second stage moving mechanism 404. , 302 is adjusted. Thereby, the shift | offset | difference of the relative position of the board | substrates 301 and 302 can be suppressed to about 2 micrometers. Then, the second substrate 302 is lowered by the Z-direction lifting and moving mechanism 406 and comes into contact with the first substrate 301. The pressure applied between the substrates 301 and 302 is measured by the stage pressure sensor 411, and the piezo actuator 412 is controlled based on the measurement result, whereby the substrates 301 and 302 are pressurized with a pressure equal to or lower than the critical pressure.

  When the temporary bonding of the substrates 301 and 302 is completed, the second substrate 302 is raised by the Z-direction lifting and moving mechanism 406 and separated from the first substrate 301 (step S15). In the temporary bonding in step S14 described above, the substrates 301 and 302 are pressurized at a pressure equal to or lower than the critical pressure. Therefore, the separation of the substrates 301 and 302 in step S15 does not damage the substrates 301 and 302. It can be done easily.

  After that, the bonding surface of the first substrate 301 and the bonding surface of the second substrate 302 are brought into contact again, and the substrates 301 and 302 are pressurized with a pressure higher than the critical pressure, whereby the first substrate 301 and the first substrate 301 are bonded to each other. The two substrates 302 are joined (step S16). Also at the time of bonding the substrates 301 and 302 in step S16, the relative positions of the substrates 301 and 302 are measured by the position measuring unit 500, and the relative positions of the substrates 301 and 302 are adjusted again by the alignment table 405 or the like. By repeating the relative position adjustment in this manner, the relative position shift between the substrates 301 and 302 can be suppressed to about 0.2 μm. Then, the second substrate 302 is lowered by the Z-direction lifting / lowering mechanism 406 to come into contact with the first substrate 301, and the substrates 301 and 302 are pressurized with a pressure larger than the critical pressure, whereby the substrates 301 and 302. The final joining of the two ends.

  As described above, in step S <b> 16, after the substrates 301 and 302 are pressurized with the Z-direction lifting / lowering mechanism 406 at a pressure lower than the critical pressure, or in parallel with the pressurization with the pressure lower than the critical pressure. Then, the substrates 301 and 302 may be finally bonded to each other by being heated by the substrate temperature adjusting unit 420. Alternatively, final bonding of the substrates 301 and 302 may be performed by heating the substrates 301 and 302 at a predetermined temperature by the substrate temperature adjusting unit 420 without pressurizing the substrates 301 and 302.

  In the substrate bonding apparatus 100, as described above, the bonding strength between the substrates 301 and 302 can be improved, and the void between the substrates 301 and 302 can be reduced. Further, the substrates 301 and 302 can be joined while improving the relative positional accuracy between the substrates 301 and 302. In the substrate bonding apparatus 100, the stage moving mechanisms 403 and 404 are also substrate bonding mechanisms that perform temporary bonding, separation, and bonding of the substrates 301 and 302.

  The surface activation process and the hydrophilization process for the substrates 301 and 302 may be performed in different vacuum chambers. FIG. 8 is a front view showing another preferred example of the substrate bonding apparatus. FIG. 8 shows a schematic structure inside the substrate bonding apparatus (the same applies to FIG. 9). In the substrate bonding apparatus 100a shown in FIG. 8, a second vacuum chamber 250 (for example, a load lock chamber) that can be evacuated by a vacuum pump is provided in addition to the vacuum chamber 200, and the hydrophilic treatment section 620 is provided in the second vacuum chamber 250. Is provided.

  In the substrate bonding apparatus 100a, a vacuum chamber 200 (hereinafter also referred to as “first vacuum chamber 200”) and a second vacuum chamber 250 are connected via a vacuum valve 230 that can be opened and closed. In the substrate bonding apparatus 100a, the substrates 301 and 302 are transferred between the first vacuum chamber 200 and the second vacuum chamber 250 by the substrate transfer mechanism 270 without being exposed to the atmosphere. In the first vacuum chamber 200, a surface activation process (step S11) is performed on the bonding surfaces of the substrates 301 and 302 in the same manner as described above. In the second vacuum chamber 250, hydrophilic treatment and adhesion of water molecules (steps S12 and S13) are performed on the bonding surfaces of the substrates 301 and 302.

  In the substrate bonding apparatus 100a, the first vacuum chamber 200 and the second vacuum chamber 250 constitute a vacuum chamber system in which a surface activation process and a hydrophilization process are performed on the substrates 301 and 302. Thereby, the space for performing the hydrophilic treatment on the substrates 301 and 302 and the space for performing the surface activation treatment on the substrates 301 and 302 can be separated. In addition, a space for performing hydrophilic treatment of the substrates 301 and 302 and a space for bonding the substrates 301 and 302 can be separated.

  In the vacuum chamber system, the bonding surfaces of the substrates 301 and 302 that have been subjected to the surface activation process can be subjected to a hydrophilic treatment without exposing the bonding surfaces to the atmosphere. Further, it is possible to suppress the water vapor or the like in the second vacuum chamber 250 from flowing into the first vacuum chamber 200, and to easily maintain a high degree of vacuum in the first vacuum chamber 200 for a long time. Furthermore, the surface activation process for the bonding surface of one substrate and the hydrophilic treatment for the bonding surface of another substrate can be performed in parallel. For this reason, the substrate processing efficiency in the substrate bonding apparatus 100 can be improved.

  In the substrate bonding apparatus 100, the temporary bonding process in step S14 may be performed, for example, in a vacuum state in the vacuum chamber 200, and a state in which the atmosphere is introduced into the first vacuum chamber 200 (that is, in the atmosphere). ). Compared to the case where the substrates 301 and 302 are temporarily bonded in a vacuum as described above, the temporary bonding process in step S14 is performed in a state where the atmosphere is introduced into the first vacuum chamber 200. The bonding strength between the substrates 301 and 302 after step S16 can be further improved.

  The adhesion of water molecules to the bonding surface in step S13 may be performed by a method other than cooling of the substrates 301 and 302. For example, the substrates 301 and 302 that have been subjected to the hydrophilic treatment in step S <b> 12 in the substrate bonding apparatus 100 are unloaded from the substrate bonding apparatus 100, and are washed by a water cleaning unit provided outside the substrate bonding apparatus 100. By performing water washing on the bonding surface, water molecules may adhere to the bonding surface in step S13. Further, the hydrophilization treatment in step S12 is also performed by being carried out from the substrate bonding apparatus 100 and exposed to the atmosphere, or by introducing the atmosphere into the second vacuum chamber 250 and exposing it to the atmosphere. Also good.

FIG. 9 is a front view showing another preferred example of the substrate bonding apparatus. In the substrate bonding apparatus 100b shown in FIG. 9, the line type particle beam source and the shielding member are omitted from the first vacuum chamber 200 of the substrate bonding apparatus 100a shown in FIG. 8, and an RIE (Reactive Ion Etching) mechanism is provided in the second vacuum chamber 250. 613 is provided as the surface activation processing unit 610. The RIE mechanism 613 includes a cathode 614 provided on a stage 251 that holds a substrate in the second vacuum chamber 250, and a reaction gas supply unit 615 that supplies a reaction gas to the second vacuum chamber 250. For example, argon (Ar), nitrogen (N ₂ ), oxygen (O ₂ ), or the like is used as the reaction gas.

  The RIE mechanism 613 converts the reactive gas into plasma by applying electromagnetic waves or the like to the reactive gas supplied from the reactive gas supply unit 615 into the second vacuum chamber 250. The RIE mechanism 613 applies a high-frequency voltage to the cathode 614 provided on the stage 251 that supports the substrate. Thereby, a self-bias potential is generated between the substrate and the plasma, and ions and radical species in the plasma are accelerated toward the substrate and collide with each other. Thereby, the surface activation process with respect to the joint surface of the board | substrate in above-mentioned step S11 is performed. In the substrate bonding apparatus 100b, the substrates 301 and 302 are carried one by one into the second vacuum chamber 250, and the surface activation process is sequentially performed on the substrates 301 and 302.

  In the substrate bonding apparatus 100b, after the surface activation processing of the substrates 301 and 302 is performed by the RIE mechanism 613, the hydrophilic treatment in step S12 is performed in the second vacuum chamber 250 as in the substrate bonding apparatus 100a illustrated in FIG. Done. In addition, steps S13 to S16 are performed as in the substrate bonding apparatus 100a.

  In the surface activation process in the substrate bonding apparatus 100b, for example, a reactive gas is supplied from the reactive gas supply unit 615 to 20 sccm into the second vacuum chamber 250 having an atmospheric pressure of about 30 Pa (Pascal), and a 100 W RIE plasma process is performed. Is performed for about 30 seconds, whereby the surface activation processing of the substrates 301 and 302 is performed. In the substrate bonding apparatus 100b, since the surface activation processing of the substrates 301 and 302 is performed by plasma, the degree of vacuum of the space in which the surface activation processing is performed can be made relatively low. Therefore, the structure of the substrate bonding apparatus 100b can be simplified, and the manufacturing cost of the substrate bonding apparatus 100b can be reduced. On the other hand, when the bonding surfaces of the substrates 301 and 302 are formed of a mixed material of a metal and an insulator, and there is a concern about mixing of impurities or materials on the bonding surface by the RIE mechanism 613, the surface by the particle beam irradiation described above. An activation treatment may be preferred.

  The surface activation treatment of the substrates 301 and 302 by plasma may be performed in a space different from a space (for example, the second vacuum chamber 250) in which the hydrophilic treatment is performed on the substrates 301 and 302. For example, as illustrated in FIG. 10, a plasma processing unit 616 including a plasma chamber 617 and an electrode stage 618 may be provided as the surface activation processing unit 610. In the plasma processing unit 616, for example, only the surface activation process for the substrates 301 and 302 is performed. The plasma chamber 617 and the electrode stage 618 are made of, for example, aluminum (Al). The electrode stage 618 is connected to a high frequency power source, and the plasma chamber 617 is installed. The electrode stage 618 and the plasma chamber 617 are electrically insulated by an insulator 619 such as glass. Substrates 301 and 302 (substrate 301 in FIG. 10) are held on electrode stage 618 in plasma chamber 617. By applying a high frequency voltage to the electrode stage 618, a surface activation process is performed on the bonding surfaces of the substrates 301 and 302 in the same manner as the RIE mechanism 613 described above. In the plasma processing unit 616, a radical downflow mechanism that supplies plasma to the internal space of the plasma chamber 617 may be provided above the plasma chamber 617.

  FIG. 11 is a plan view showing another preferred example of the substrate bonding apparatus. A substrate bonding apparatus 100 c illustrated in FIG. 11 includes a substrate processing unit 101, a water cleaning unit 102, a temporary bonding unit 103, and a bonding unit 104. The substrate processing unit 101 has, for example, substantially the same structure as the above-described substrate bonding apparatus 100a (see FIG. 8). In the substrate processing unit 101, surface activation processing is performed on the bonding surfaces of the substrates 301 and 302 in the first vacuum chamber 200, and hydrophilic processing is performed on the bonding surfaces of the substrates 301 and 302 in the second vacuum chamber 250.

  The water cleaning unit 102 attaches water molecules to the bonding surfaces of the substrates 301 and 302 by performing water cleaning on the bonding surfaces of the substrates 301 and 302 that have been subjected to the surface activation process and the hydrophilization process. The water cleaning of the joint surface by the water cleaning unit 102 is performed, for example, by spraying a water flow provided with ultrasonic waves toward the substrates 301 and 302 in the atmosphere. The adhesion of water molecules to the bonding surfaces of the substrates 301 and 302 is performed by cooling the bonding surfaces of the substrates 301 and 302 by the substrate temperature adjusting unit 420 in the substrate processing unit 101, and further by the water cleaning unit 102. It may be performed by washing with water.

  The temporary bonding unit 103 temporarily bonds the substrates 301 and 302 by bringing the bonding surfaces of the substrates 301 and 302 into contact with each other and pressurizing the substrates 301 and 302 with a pressure equal to or lower than the critical pressure. The temporary bonding unit 103 has, for example, substantially the same configuration as the substrate support unit 400 and the position measurement unit 500 of the substrate bonding apparatus 100 shown in FIG. When the temporary bonding of the substrates 301 and 302 in the temporary bonding portion 103 is performed in the atmosphere, the temporary bonding portion 103 does not need to be provided with a configuration such as a vacuum chamber.

  For example, the bonding unit 104 has a structure in which the surface treatment unit 600 is omitted from the substrate bonding apparatus 100 illustrated in FIG. 1. The bonding portion 104 separates the temporarily bonded substrates 301 and 302 in a vacuum. Thereafter, the bonding surfaces of the substrates 301 and 302 are brought into contact again in vacuum, and the substrates 301 and 302 are bonded together by pressurizing the substrates 301 and 302 at a pressure higher than the critical pressure.

  In the substrate bonding apparatus 100c, water cleaning is performed on the bonding surfaces of the substrates 301 and 302 in the water cleaning unit 102, so that water molecules can be easily attached to the bonding surfaces, and particles can be removed from the bonding surfaces. Etc. can also be removed. In addition, since the substrates 301 and 302 are temporarily bonded in the atmosphere at the temporary bonding portion 103, as compared with the case where the temporary bonding of the substrates 301 and 302 is performed in a vacuum as described above, step S16 is performed. It is possible to further improve the bonding strength between the substrates 301 and 302 after the completion of the step.

  Table 1 below shows the bonding strength between the substrates and the number of voids between the substrates when the substrates are bonded under various conditions.

  The first column in Table 1 shows the case name, and the second column shows the presence / absence of the water molecule adhesion treatment in step S13 and the method of the adhesion treatment. The third row indicates whether or not the substrate is temporarily bonded in step S14, and the fourth column indicates whether or not the substrate is peeled in step S15 and the atmosphere (in the air or in vacuum) when the substrate is peeled off. Show. The fifth column shows the atmosphere (in air or vacuum) of the space where the main bonding between the substrates is performed. The sixth column shows the bonding strength between the substrates after the main bonding, and the seventh column shows the number of voids between the substrates after the main bonding. The case described as “low” in the seventh column indicates that there are relatively few voids between the substrates, or there are no voids.

Table 1 shows the bonding results between the SiO ₂ substrates. SiO ₂ includes a thermal oxide film, CVD, glass and the like. Although not described in the table, in cases 1 to 10, the surface activation process (step S11) by particle beam irradiation using a fast atom beam source (FAB) before step S13, and the above-described steps are performed. The hydrophilic treatment (step S12) is performed. Cases 1 to 6 are experimental results of comparative examples for comparison with the present invention. Cases 7 to 10 are experimental results according to the present invention. In addition, when the surface activation process in step S11 was performed by the above-described method (for example, ion beam source or plasma) other than the fast atom beam source (FAB), the same result as in Table 1 was confirmed. The same results as in Table 1 were confirmed for substrates other than the SiO ₂ substrate (for example, a substrate having a nitride film, a compound semiconductor, and an Lt (lithium tantalate) substrate).

In Cases 1 to 3, Steps S14 and S15 are not performed, and the substrates after Step S12 or Step S13 are placed opposite to each other in the vacuum chamber, and then evacuated and bonded in a vacuum. It is. In cases 1 to 3, the bonding strength is relatively low at 0.2 to 0.3 J / m ^2, which can be said to be insufficient bonding. In cases 4 to 6, steps S14 and S15 are not performed, and the substrate after step S12 or step S13 is bonded in the atmosphere. In cases 4 to 6, the bonding strength is relatively high at 2.0 to 2.5 J / m ² and it can be said that the bonding is sufficient, but there are many voids between the substrates.

  In case 7, step S13 is not performed, and the substrates subjected to the hydrophilization process in step S12 are temporarily bonded in the air (step S14) and separated in the air (step S15). Then, after the two substrates after peeling are arranged to face each other in the vacuum chamber, vacuuming is performed and main bonding is performed in a vacuum (step S16). In case 8, step S13 is not performed, and the substrates subjected to the hydrophilic treatment in step S12 are temporarily joined in the atmosphere (step S14). Then, after both substrates in the temporarily bonded state are placed in the vacuum chamber, evacuation is performed, the substrates are separated from each other in vacuum, and finally bonded in vacuum (steps S15 and S16). Case 9 is a case where water molecule adhesion processing (step S13) by cooling is performed between step S12 and step S14 of case 8. Case 10 is obtained by performing water molecule adhesion processing (step S13) by water washing between step S12 and step S14 of case 8.

In Cases 7 to 10, the bonding strength is 1.8 to 2.5 J / m ^2, which is sufficiently higher than Cases 1 to 3 and equivalent to Cases 4 to 6. Further, unlike the cases 4 to 6, the cases 7 to 10 have few (or substantially no) voids between the substrates. Thus, in this invention, while improving the joint strength of board | substrates, the void between board | substrates can be reduced.

  Various modifications can be made in the substrate bonding apparatus 100 described above.

  For example, the particle beam source 601 of the surface activation processing unit 610 is not limited to a line type, and a non-line type particle beam source may be used.

  The pressurization of the substrates 301 and 302 in steps S14 and S16 described above and the separation of the substrates 301 and 302 in step S15 may be performed by a configuration other than the Z-direction lifting and moving mechanism 406. For example, by applying an opposite charge to the substrates 301 and 302, the substrates 301 and 302 may be electrically pressurized using the attractive force of static electricity due to the charges. Separation of the temporarily bonded substrates 301 and 302 may be performed by mechanically inserting a blade or blowing a fluid such as water or air in the surface direction from the edge of the substrates 301 and 302.

  As described above, various materials are used for the substrate. The materials to be joined at both joining surfaces may be various. For example, a semiconductor typified by silicon, a metal such as copper, aluminum, or gold, or an insulator such as silicon oxide, silicon nitride, or resin may be used. In the substrate bonding apparatuses 100, 100a to 100c, since various materials can be bonded, it is possible to seal the circuit without using a sealant when the substrates are bonded to each other. Furthermore, the lamination of substrates by surface bonding and the surface bonding of large substrates are also realized.

  The configurations in the above-described embodiments and modifications may be combined as appropriate as long as they do not contradict each other.

100, 100a to 100c Substrate bonding apparatus 102 Water cleaning unit 200 Vacuum chamber 301, 302 Substrate 403, 404 Stage moving mechanism 420 Substrate temperature adjustment unit 610, 613, 617 Surface activation processing unit 611 Shielding surface 620 Hydrophilization processing unit S11- S16 step

Claims (14)

A substrate bonding apparatus,
A vacuum chamber;
A surface activation processing unit for activating the first bonding surface of the first substrate and the second bonding surface of the second substrate in the vacuum chamber;
After activation by the surface activation processing unit, the first bonding surface and the second bonding surface that have been subjected to hydrophilic treatment are brought into contact with each other, and the first substrate and the second substrate are pressed against each other. Thus, the first substrate and the second substrate are temporarily bonded, the first substrate after the temporary bonding and the second substrate are separated, and the first bonding surface in a state of being separated in a vacuum and the first substrate A substrate bonding mechanism that contacts the second bonding surface to bond the first substrate and the second substrate;
A substrate bonding apparatus comprising: The substrate bonding apparatus according to claim 1,
A substrate bonding apparatus, wherein temporary bonding between the first substrate and the second substrate is performed in the atmosphere. The substrate bonding apparatus according to claim 1 or 2,
The substrate bonding apparatus, wherein the first substrate and the second substrate after temporary bonding are separated in a vacuum. A substrate bonding apparatus according to any one of claims 1 to 3,
In parallel with the hydrophilic treatment, or between the hydrophilic treatment and the temporary bonding by the substrate bonding mechanism, water molecules are attached to the first bonding surface and the second bonding surface. Substrate bonding device. The substrate bonding apparatus according to claim 4,
A substrate bonding apparatus, further comprising a substrate cooling unit that cools the first bonding surface and the second bonding surface to attach water molecules to the first bonding surface and the second bonding surface. The substrate bonding apparatus according to claim 4 or 5, wherein
The substrate bonding apparatus, wherein adhesion of water molecules to the first bonding surface and the second bonding surface is performed by supplying a gas containing water molecules into the vacuum chamber. The substrate bonding apparatus according to any one of claims 4 to 6,
The substrate further comprising a water cleaning unit that performs water cleaning on the first bonding surface and the second bonding surface to attach water molecules to the first bonding surface and the second bonding surface. Joining device. A substrate bonding method,
a) activating the first bonding surface of the first substrate and the second bonding surface of the second substrate in a vacuum;
b) after the step a), performing a hydrophilic treatment on the first joint surface and the second joint surface;
c) Temporarily bonding the first substrate and the second substrate by bringing the first bonding surface and the second bonding surface into contact with each other and pressing the first substrate and the second substrate against each other. Process,
d) a step of separating the first substrate temporarily bonded in the step c) and the second substrate;
e) bonding the first substrate and the second substrate by bringing the first bonding surface and the second bonding surface in a separated state in a vacuum into contact with each other;
A substrate bonding method comprising: The substrate bonding method according to claim 8, wherein
In the step c), the first bonding surface and the second bonding surface are in contact with each other in the atmosphere. A substrate bonding method according to claim 8 or 9, wherein
The substrate bonding method, wherein the step d) is performed in a vacuum. A substrate bonding method according to any one of claims 8 to 10,
f) The method further comprises a step of attaching water molecules to the first joint surface and the second joint surface in parallel with the step b) or between the step b) and the step c). A substrate bonding method. The substrate bonding method according to claim 11,
The substrate bonding method, wherein the step f) includes a step of cooling the first bonding surface and the second bonding surface. The substrate bonding method according to claim 11 or 12,
The substrate bonding method, wherein the adhesion of water molecules to the first bonding surface and the second bonding surface in the step f) is performed by supplying a gas containing water molecules . A substrate bonding method according to any one of claims 11 to 13,
The substrate bonding method, wherein the step f) includes a step of performing water cleaning on the first bonding surface and the second bonding surface.

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