Wafer-to-wafer bonding method and wafer-to-wafer bonding equipment

Abstract

In a wafer-to-wafer bonding method, a first wafer is vacuum-adsorbed onto the first surface of a lower platform, and a second wafer is vacuum-adsorbed onto the second surface of an upper platform. Pressure is applied to the center of the first wafer by a lower push rod, and pressure is applied to the center of the second wafer by an upper push rod. The bonding of the first and second wafers propagates radially outward. The propagation position of the bonding between the first and second wafers is detected. The ratio of the protruding length of the lower push rod to the protruding length of the upper push rod changes depending on the propagation position of the bonding.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Korean Patent Application No. 10-2019-0079283 filed on July 2, 2019, in the Korean Intellectual Property Office (KIPO), the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] Some example embodiments relate to a wafer-to-wafer bonding method and a wafer-to-wafer bonding apparatus. More particularly, some example embodiments relate to a method of bonding wafers to each other to manufacture a semiconductor device having a three-dimensional connection structure and a wafer-to-wafer bonding apparatus for performing the method. Background Art

[0004] In the manufacture of electronic products such as CIS (CMOS image sensor) and HBM (high bandwidth memory), two wafers may be bonded to each other, thereby improving the productivity per wafer. The wafer-to-wafer bonding process may include an O2 plasma activation step, a hydration step, a wafer alignment step, a wafer bonding step, an annealing step, etc. Since the middle region of the wafer may be deformed and protruded during the wafer bonding step, and then may be gradually bonded from the middle region to the peripheral region, the wafer may be deformed by its own weight during the bonding propagation of the wafer, making the curvature of the wafer at the bonding point asymmetric with each other, thereby causing alignment errors. Summary of the Invention

[0005] Some example embodiments provide a wafer-to-wafer bonding method capable of preventing wafer-to-wafer misalignment.

[0006] Some example embodiments provide a wafer-to-wafer bonding apparatus for performing a wafer-to-wafer bonding method.

[0007] According to some example embodiments, a wafer bonding device may include: a vacuum pump; a lower platform having a first surface and including a plurality of first adsorption holes in the first surface, wherein the lower platform is configured to vacuum adsorb the first wafer on the first surface based on vacuum pressure being supplied from the vacuum pump to the plurality of first adsorption holes; an upper platform having a second surface and including a plurality of second adsorption holes in the second surface, wherein the upper platform is configured to vacuum adsorb the second wafer on the second surface based on vacuum pressure being supplied from the vacuum pump to the plurality of second adsorption holes; a lower push rod capable of moving through a first center hole in a middle portion of the lower platform to contact a middle area of ​​the first wafer overlapping with the first center hole and apply pressure to the middle area of ​​the first wafer; an upper push rod capable of moving through a second center hole in a middle portion of the upper platform to contact a middle area of ​​the second wafer overlapping with the second center hole and apply pressure to the middle area of ​​the second wafer; a position detection sensor configured to detect the position of the wafer based on the position of the wafer. The invention relates to a method for producing wafer position information indicating a bonding propagation position of the first wafer and the second wafer by detecting at least one of the first wafer and the second wafer through a detection hole in at least one of the lower platform and the upper platform; a platform driver configured to move the lower platform and the upper platform relative to each other; a push rod driver configured to move the lower push rod and the upper push rod in a vertical direction; wherein the vacuum pump is configured to selectively supply vacuum pressure to both the first adsorption hole and the second adsorption hole; and a processing circuit communicatively coupled to the platform driver, the push rod driver and the vacuum pump, the processing circuit being configured to control the operation of the platform driver, the push rod driver and the vacuum pump, the processing circuit being further configured to process the wafer position information to detect the bonding propagation position, and the processing circuit being further configured to change at least one of the ratio of the protruding length of the lower push rod to the protruding length of the upper push rod and the ratio of the adsorption area of ​​the upper platform to the adsorption area of ​​the lower platform according to the bonding propagation position.

[0008] According to some example embodiments, a wafer bonding device may include: a lower platform having a first surface and including a plurality of first adsorption holes in the first surface, wherein the lower platform is configured to vacuum-adsorb the first wafer on the first surface based on vacuum pressure supplied from a vacuum pump to the plurality of first adsorption holes; an upper platform having a second surface and including a plurality of second adsorption holes in the second surface, wherein the upper platform is configured to vacuum-adsorb the second wafer on the second surface based on vacuum pressure supplied from the vacuum pump to the plurality of second adsorption holes; a lower push rod movable through a first center hole in a middle portion of the lower platform to contact a middle area of ​​the first wafer overlapping with the first center hole and apply pressure to the middle area of ​​the first wafer; and an upper push rod. The upper platform includes a second platform and a second platform. The first platform includes a second platform and a second platform. The second platform includes a first platform and a second platform. The first platform includes a second platform and a second platform. The first platform includes a second platform and a second platform. The first platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform. The second platform includes a second platform and a second platform.

[0009] According to some example embodiments, while the bond between the upper and lower wafers propagates radially outward, the ratio of the protruding length of the lower push rod to the protruding length of the upper push rod or the ratio of the suction area of ​​the lower platform to the suction area of ​​the upper platform may be changed. In addition, the distance between the lower platform and the upper platform may be changed according to the position of the bond propagation.

[0010] Therefore, while the bonding of the upper wafer and the lower wafer is propagating, the curvatures of the wafers at the bonding points can be controlled to be symmetrical with each other, thereby reducing or minimizing the alignment error between the wafers, thereby improving the quality of the semiconductor device formed by such bonding, including improving the performance, reliability and / or efficiency of the semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Some example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. Figures 1 to 15 represents some non-limiting example embodiments as described herein.

[0012] Figure 1is a block diagram illustrating a wafer-to-wafer bonding system according to some example embodiments.

[0013] Figure 2 is a cross-sectional view illustrating a wafer bonding apparatus according to some example embodiments.

[0014] Figure 3 It shows Figure 2 A cross-sectional view of the initial steps of the wafer bonding process in a wafer bonding apparatus.

[0015] Figure 4 It shows Figure 2 A plan view of the upper platform of the wafer bonding equipment.

[0016] Figure 5 It shows Figure 2 Block diagram of the drive section and controller of the wafer bonding equipment.

[0017] Figure 6A and Figure 6B are cross-sectional views illustrating stages of a bonding process of a first wafer and a second wafer in a wafer bonding apparatus in some example embodiments.

[0018] Figure 7 is a graph illustrating a change in a ratio of a protruding length of a lower push rod and a protruding length of an upper push rod according to engagement propagation, according to some example embodiments.

[0019] Figure 8A and Figure 8B is a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of a protruding length of a lower push pin to a protruding length of an upper push pin at a bonding initial time.

[0020] Figure 9A and Figure 9B is a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of a protruding length of a lower push pin to a protruding length of an upper push pin at a bonding propagation time.

[0021] Figure 10A is a graph illustrating a position of a lower platform according to joint propagation according to some example embodiments, Figure 10B is a graph illustrating protruding lengths of a lower push rod and an upper push rod according to engagement propagation according to some example embodiments.

[0022] Figure 11 is a graph showing the distance between the lower platform and the upper platform at the joint propagation position.

[0023] Figure 12A 、 Figure 12B and Figure 12Cis a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of suction areas of the upper and lower platforms during bonding propagation.

[0024] Figure 13 is a flowchart illustrating a wafer-to-wafer bonding method according to some example embodiments.

[0025] Figure 14 It shows Figure 13 View of the wafer-to-wafer bonding method in Figure 2.

[0026] Figure 15 It shows Figure 13 Flowchart of the bonding phase of the wafer-to-wafer bonding method. DETAILED DESCRIPTION

[0027] Hereinafter, some example embodiments will be described in detail with reference to the accompanying drawings.

[0028] Figure 1 is a block diagram illustrating a wafer-to-wafer bonding system according to some example embodiments.

[0029] Reference Figure 1 The wafer-to-wafer bonding system 10 may include pre-processing equipment such as a plasma processing equipment 40 and a cleaning equipment 50, an alignment equipment 60, and a wafer bonding equipment 70 arranged in the clean room 20. The wafer-to-wafer bonding system 10 may further include a cassette platform 30 provided on one side of the clean room 20.

[0030] In some exemplary embodiments, clean room 20 may be an enclosed room having a rectangular parallelepiped shape and may be a controlled environment with low levels of contaminants such as, for example, dust, airborne microorganisms, aerosol particles, and chemical vapors.

[0031] The cassette platform 30 may provide a space in which wafers are located before being transferred to the clean room 20. A carrier C having a plurality of wafers accommodated therein may be supported on a support plate 32 of the cassette platform 30. The carrier C may be, for example, a front opening unified pod (FOUP). The wafers accommodated in the carrier C may be transferred to the clean room 20 by the transfer robot 22. For example, three carriers C may be provided on the cassette platform 30. In some example embodiments, a first wafer and a second wafer to be bonded to each other may be respectively accommodated in a first carrier C and a second carrier C, and the bonded wafers may be accommodated in a third carrier C.

[0032] In some example embodiments, the first wafer may be a wafer having circuits for an image sensor chip formed therein, and the second wafer may be a wafer having photosensors for the image sensor chip formed therein, so that the image sensor chip may be formed based on bonding the first wafer and the second wafer together to form an image sensor chip including the circuits and the photosensors. Alternatively, in some example embodiments, the first wafer may be a wafer having circuits for a semiconductor package (e.g., high bandwidth memory (HBM)) formed therein, and the second wafer may be a wafer having memories for the semiconductor package formed therein, so that the semiconductor package may be formed based on bonding the first wafer and the second wafer together to form a semiconductor package including the circuits and the memories.

[0033] The plasma processing device 40 may perform plasma processing on the surface of the wafer W. The plasma processing device 40 may be a device configured to process plasma on the surface of the wafer W disposed in an ICP (inductively coupled plasma) chamber to form dangling bonds on the surface of the wafer W. However, the plasma generated by the plasma processing device is not limited to the inductively coupled plasma used in the ICP chamber. For example, some example embodiments may use capacitively coupled plasma, microwave plasma, etc. that can be generated by the plasma processing device.

[0034] The cleaning device 50 can clean the surface of the wafer that has been plasma-treated by the plasma treatment device 40. The cleaning device 50 can apply deionized (DI) water to the wafer surface using a spin coater. The DI water can clean the wafer surface and allow -OH radicals to easily bond to the wafer surface, so that dangling bonds are easily generated on the wafer surface.

[0035] The alignment apparatus 60 may detect a flat portion (or a cut portion) of the wafer W to align the wafer W. The wafer aligned by the alignment apparatus 60 may be transferred to the plasma processing apparatus 40 or the wafer bonding apparatus 70 by the transfer robot 22 .

[0036] In the following, we will Figure 1 The wafer bonding equipment will be described.

[0037] Figure 2 is a cross-sectional view illustrating a wafer bonding apparatus according to some example embodiments. Figure 3 It shows Figure 2 Cross-sectional view of the initial steps of the wafer bonding process in the wafer bonding equipment. Figure 4 It shows Figure 2 A plan view of the upper platform of the wafer bonding equipment. Figure 5 It shows Figure 2 Block diagram of the drive section and controller of the wafer bonding equipment.

[0038] Reference Figures 2 to 5 The wafer bonding apparatus 70 may include a lower chuck structure 100, an upper chuck structure 200, a first wafer pushing unit 310, a second wafer pushing unit 320, and a position detection sensor 400. Furthermore, the wafer bonding apparatus 70 may further include multiple drive units and a controller 500 configured to control the operation of the drive units. In some example embodiments, the wafer bonding apparatus 70 may omit the drive units described herein. Again, the drive units may be separate from the wafer bonding apparatus 70.

[0039] In some example embodiments, the lower chuck structure 100 may include a lower platform 110 that holds the first wafer W1. The lower platform may be understood as a structure having a surface and structure configured to structurally support the first wafer W1 (e.g., support the weight of the first wafer W1) and hold it in place. The lower platform 110 may have a first surface 112 on which the first wafer W1 is disposed (e.g., the first wafer W1 is resting on the first surface 112). The first adsorption holes 130 may be disposed in the first surface 112 of the lower platform 110. Again, the lower platform 110 may include a plurality of first adsorption holes 130 that extend at least through the first surface 112 so as to become holes in the first surface 112, wherein each of the first adsorption holes 130 at least partially defines one end of a first adsorption conduit 131 that couples the one or more first adsorption holes 130 to a vacuum pump (e.g., the vacuum pump 240). Therefore, it will be understood that the plurality of first adsorption holes 130 may be coupled to a first vacuum pump (e.g., vacuum pump 240) via one or more first adsorption ducts 131, such that the vacuum pump 240 may provide vacuum pressure to the first adsorption holes 130 via the first adsorption ducts 131, and thus may apply vacuum force on at least a portion of an object (such as a first wafer W1), the first wafer W1 being rested on the first surface 112 so as to at least partially cover the one or more first adsorption holes 130, as shown. Figure 2 As shown. Therefore, based on the vacuum applied through the first adsorption holes 130, the first wafer W1 can be vacuum-adsorbed by the first adsorption holes 130 of the lower platform 110. Therefore, it will be understood that the lower platform 110 can vacuum-adsorb the first wafer W1 on the first surface 112 via the first adsorption holes 130, wherein when a vacuum is applied by a vacuum source through the first adsorption holes 130, an adsorption force is generated by applying a vacuum to one or more portions of the first wafer W1 that partially or completely cover one or more first adsorption holes 130.

[0040] like Figure 2As shown, the wafer bonding apparatus 70 may include a set of fluid control valves 132, each of which may couple a separate adsorption conduit 131 to the vacuum pump 240 and may be each adjustable to adjustably control fluid communication between the vacuum pump 240 and corresponding one or more adsorption holes, the one or more adsorption holes being coupled to the fluid control valve 132 via at least some portions of the adsorption conduits 131. It will be understood that in some example embodiments, a given fluid control valve 132 may couple multiple adsorption conduits coupled in parallel with the fluid control valve 132 to the vacuum pump 240, such that the fluid control valve 132 may be configured to control fluid communication between the vacuum pump and the multiple adsorption conduits 131. The vacuum pump 240 and / or the controller 500 described herein may independently control the adjustment position (e.g., open, closed, partially open, etc.) of each of these fluid control valves 132 to independently and selectively control the application of vacuum pressure from the vacuum pump 240 to a selected adsorption conduit 131 and, therefore, to the selected first adsorption hole 130. This control can be based on a control signal generated by the controller 500 and communicated directly to one or more fluid control valves 132 or to the vacuum pump 240 so that the vacuum pump 240 controls the one or more fluid control valves 132 (for example, in an example embodiment where the valves 132 are included in the vacuum pump 240). Therefore, it will be understood that the controller 500 can be configured so that vacuum pressure is selectively and independently applied to selected one or more of the first adsorption holes 130.

[0041] The upper chuck structure 200 may include an upper platform 210 that holds the second wafer W2. The upper platform 210 may be understood as a structure having a surface and structure configured to structurally support the second wafer W2 (e.g., support the weight of the second wafer W2) and hold it in place. The upper platform 210 may be arranged to face the lower platform 110. The upper platform 210 may have a second surface 212 on which the second wafer W2 is disposed. Second adsorption holes 230 may be disposed in the second surface 212 of the upper platform 210. Again, the upper platform 210 may include a plurality of second adsorption holes 230 that extend at least through the second surface 212 so as to become holes in the second surface 212, wherein each of the second adsorption holes 230 at least partially defines one end of an adsorption conduit 231 (e.g., an adsorption conduit) that couples the one or more second adsorption holes 230 to a vacuum pump (e.g., a vacuum pump 240). Therefore, it will be understood that the plurality of second adsorption holes 230 may be coupled to a second vacuum pump (which may be the same as or different from the first vacuum pump (e.g., vacuum pump 240)) via one or more second adsorption ducts 231, such that vacuum pressure may be supplied to the second adsorption holes 230 via the second adsorption ducts 231, and thus a vacuum force may be applied on at least a portion of an object (such as a second wafer W2) that is in contact with the second surface 212 so as to at least partially cover the one or more second adsorption holes 230, as shown. Figure 2 As shown. It will be understood that the vacuum pump 240 can supply the same vacuum pressure to the first adsorption holes 130 and the second adsorption holes 230. Therefore, based on the vacuum applied through the second adsorption holes 230, the second wafer W2 can be vacuum adsorbed by the second adsorption holes 230 of the upper platform 210, wherein the vacuum force generated on the second wafer W2 is at least sufficient to overcome the weight of the second wafer W2 and hold the second wafer W2 in place against the second surface 212. Therefore, it will be understood that the upper platform 210 can vacuum adsorb the second wafer W2 on the second surface 212 via the second adsorption holes 230, wherein when a vacuum is applied by a vacuum source through the second adsorption holes 230, an adsorption force is generated by applying a vacuum to one or more portions of the second wafer W2 that partially or completely cover one or more second adsorption holes 230.

[0042] like Figure 2As shown, the wafer bonding apparatus 70 may include a set of fluid control valves 232, each of which may couple a separate adsorption conduit 231 to a vacuum pump 240 and may be individually adjustable to adjustably control fluid communication between the vacuum pump 240 and corresponding one or more adsorption holes, the one or more adsorption holes being coupled to the fluid control valve 232 via at least some portions of the adsorption conduits 231. It will be understood that in some example embodiments, a given fluid control valve 232 may couple multiple adsorption conduits coupled in parallel with the fluid control valve 232 to the vacuum pump 240, such that the fluid control valve 232 may be configured to control fluid communication between the vacuum pump and the multiple adsorption conduits 231. The vacuum pump 240 and / or the controller 500 described herein may independently control the adjustment position (e.g., open, closed, partially open, etc.) of each of these fluid control valves 232 to independently and selectively control the application of vacuum pressure from the vacuum pump 240 to a selected adsorption conduit 231 and, therefore, to a selected second adsorption hole 230. This control can be based on a control signal generated by the controller 500 and communicated directly to one or more fluid control valves 232 or to the vacuum pump 240 so that the vacuum pump 240 controls the one or more fluid control valves 232 (for example, in an example embodiment where the valves 232 are included in the vacuum pump 240). Therefore, it will be understood that the controller 500 can be configured so that vacuum pressure is selectively and independently applied to selected one or more of the second adsorption holes 230.

[0043] The first adsorption holes 130 of the lower platform 110 and the second adsorption holes 230 of the upper platform 210 may be arranged to correspond to each other. That is, the first adsorption holes 130 and the second adsorption holes 230 may be arranged mirror-symmetrically to each other.

[0044] like Figures 2 to 4 As shown, the second adsorption holes 230 can be arranged in the peripheral area 210P of the upper platform 210 to provide (e.g., define) an external adsorption area. The second adsorption holes 230 can adsorb the peripheral portion of the second wafer W2. Although not shown in the figure, internal adsorption holes can be additionally formed in the middle area of ​​the upper platform 210 to provide an internal adsorption area. Because the first adsorption holes 130 correspond to the second adsorption holes 230, a detailed description of the first adsorption holes 130 will be omitted.

[0045] The second suction hole 230 may have a first suction portion Z1, a second suction portion Z2, and a third suction portion Z3 arranged sequentially in a radial direction from the center. For example, each of the first to third suction portions Z1, Z2, and Z3 may include eight arc-shaped segments to form a completely annular shape. In some example embodiments, each of the first to third suction portions has eight arc-shaped segments, however, this is not limited to this. For example, the suction portion may have 8 to 64 (such as 16, 32, 64, etc.) arc-shaped segments.

[0046] The second adsorption holes 230 (adsorption region II) may be located in the peripheral region 210P of the upper platform 210 (eg, at least as large as 210P). Figures 2 to 4 As shown, the first adsorption holes 130 are arranged and / or extend annularly around the center 210C of the upper platform 210), for example, located at least 0.6R (for example, 60%) of the radius (R) from the center (210C) of the upper platform 210 to the outer edge (210E) of the upper platform 210, preferably, 0.8R or greater (for example, at least 0.8R). Similarly, the first adsorption holes 130 (adsorption area I) can be located in the peripheral area 110P of the lower platform 110 (for example, at least as shown). Figures 2 to 4 As shown, the first suction portion Z1 may be annularly arranged and / or extending around the center 110C of the lower platform 110, for example, located at least 0.6R (e.g., 60%) of the radius (R) from the center (110C) of the lower platform 110 to the outer edge (110E) of the lower platform 110, preferably, 0.8R or greater (e.g., at least 0.8R). In the case where the wafer has a diameter of 300 mm, the first suction portion Z1 may have an inner radius of approximately 133 mm and an outer radius of approximately 136 mm from the center of the upper platform 210, the second suction portion Z2 may have an inner radius of approximately 139 mm and an outer radius of approximately 142 mm from the center of the upper platform 210, and the third suction portion Z3 may have an inner radius of approximately 145 mm and an outer radius of approximately 148 mm from the center of the upper platform 210. The width of each of the first to third adsorption portions Z1, Z2, Z3 in the radial direction may be about 3 mm, however, it may not be limited thereto, for example, the width in the radial direction may range from about 1 mm to about 5 mm.

[0047] When the term "about" or "substantially" is used in conjunction with a numerical value in this specification, it means that the associated numerical value includes a tolerance of ±10% around the numerical value. When a range is specified, the range includes all values ​​therebetween, for example, increments of 0.1%.

[0048] Each of the annular first to third suction sections Z1, Z2, and Z3 may include a plurality of arcuate grooves. For example, each of the first to third suction sections Z1, Z2, and Z3 may include eight arcuate grooves. Each groove may have a central angle of approximately 45 degrees. It is understood that the number and shape of the suction sections and grooves are not limited thereto.

[0049] The first to third adsorption sections Z1, Z2, and Z3 can be connected to the vacuum pump 240 via one or more pipelines (e.g., one or more second adsorption conduits 231). For example, vacuum pressure can be supplied (e.g., applied, guided, etc.) to the eight arcuate sections of the first adsorption section Z1 independently or in groups (e.g., arcuate grooves facing each other).

[0050] The vacuum pump 240 can be connected to the controller 500 and controlled by the controller 500 to supply vacuum pressure to the first to third adsorption sections Z1, Z2, and Z3. In addition, the vacuum pump 240 can supply (e.g., apply, guide, etc.) vacuum pressure to each of the sections of the first to third adsorption sections Z1, Z2, and Z3. It will be understood that the vacuum pump 240 can include a set of valves 132, 232 that can be individually controlled based on a control signal provided from the controller 500 to the vacuum pump 240 to selectively control the supply of vacuum pressure to separate corresponding adsorption conduits (e.g., adsorption conduits 131, 231) to control the selective supply of vacuum pressure to each adsorption section defined by the first adsorption hole 130 and / or the second adsorption hole 230.

[0051] For example, when vacuum pressure is applied to the first to third suction sections Z1, Z2, and Z3 (Z1, Z2, and Z3 are on), a first vacuum region having a first suction area can be formed in the peripheral area of ​​the upper platform 210. When vacuum pressure is applied to the second and third suction sections Z2 and Z3 (Z2 and Z3 are on), a second vacuum region having a second suction area smaller than the first suction area can be formed in the peripheral area of ​​the upper platform 210. When vacuum pressure is applied to the third suction section Z3 (Z3 is on), a third vacuum region having a third suction area smaller than the second suction area can be formed in the peripheral area of ​​the upper platform 210.

[0052] exist Figure 2 and Figure 3 , the first to third adsorption parts Z1, Z2, Z3 of the upper platform 210 can be shown by the section lines (Z1, Z2, Z3: connected), and the first to third adsorption parts Z1, Z2, Z3 of the lower platform 110 can be shown by the section lines (Z1, Z2, Z3: connected).

[0053] As described later, the ratio of the suction areas of the upper platform 210 and the lower platform 110 can be controlled to change according to bonding propagation (e.g., based on a control signal generated by the controller 500 and sent to one or more components of the wafer bonding apparatus 70). The suction area formed in the upper platform 210 (suction area II) can be controlled to be asymmetric with the suction area formed in the lower platform 110 (suction area I). ​​For example, at a first point in time of bonding propagation, a suction area of ​​a first suction area can be provided in the upper platform 210, and a suction area of ​​a third suction area can be provided in the lower platform 110.

[0054] The first wafer W1 and the second wafer W2 can be held in various ways. For example, as described above, the first wafer W1 and the second wafer W2 can be vacuum-adsorbed by the first adsorption holes 130 and the second adsorption holes 230, respectively. Alternatively, the first wafer W1 and the second wafer W2 can be adsorbed using electrostatic force, such as an electrostatic chuck. In this case, the ratio of the adsorption areas of the upper platform 210 and the lower platform 110 can be controlled to change according to the bonding propagation.

[0055] In some example embodiments, the lower chuck structure 100 may include a lower platform driving portion 120 (also referred to herein as a lower platform driver) configured to move the lower platform 110. The lower platform driving portion 120 may include a horizontal driving portion and a rotational driving portion, the horizontal driving portion being configured to translate the lower platform 110 in the X, Y, and Z directions, and the rotational driving portion being configured to rotate the lower platform 110 about the Z axis.

[0056] The lower platform 110 can be installed so as to be movable translationally and rotationally by the lower platform driving unit 120, so that the relative position between the upper platform 210 and the lower platform 110 can be adjusted. As will be described later, the lower platform 110 can be moved upward and downward in the Z direction by the lower platform driving unit 120. Therefore, the lower platform 110 can move the first wafer W1 adsorbed thereon toward the second wafer W2 adsorbed on the upper platform 210.

[0057] The upper chuck structure 200 may include an upper platform drive portion 220 (also referred to herein as an upper platform drive) configured to move the upper platform 210. The upper platform drive portion 220 may perform similar functions to the lower platform drive portion 120. In some example embodiments, the wafer bonding apparatus 70 may include one or both of the lower platform drive portion 120 and the upper platform drive portion 220. Each of the lower platform drive portion 120 and the upper platform drive portion 220 may be individually understood as a platform drive configured to move one or both of the lower platform 110 and the upper platform 210 relative to each other. In some example embodiments, the lower platform drive portion 120 and / or the upper platform drive portion 220 may be collectively referred to as a single platform drive; such a platform drive may be configured to move both the lower platform 110 and the upper platform 210 individually or in coordination with each other. In some example embodiments, the lower platform drive portion 120 and / or the upper platform drive portion 220 may include piston actuators.

[0058] In some example embodiments, the first wafer pushing unit 310 may include a lower push rod 312 and a lower push rod driving portion 314 (also referred to as a lower push rod driver). The second wafer pushing unit 320 may include an upper push rod 322 and an upper push rod driving portion 324 (also referred to herein as an upper push rod driver). The lower push rod driving portion 314 and / or the upper push rod driving portion 324 may each be a piston actuator. The lower push rod driving portion 314 and / or the upper push rod driving portion 324 may be collectively referred to as a push rod driver, which is configured to move the lower push rod 312 and the upper push rod 322 in a vertical direction (e.g., in a Z direction, extending parallel to the longitudinal axis of the lower push rod 312 and the upper push rod 322).

[0059] The lower push rod driving portion 314 can be connected to the controller 500 and controlled by the controller 500, and can move the lower push rod 312 upward and downward. Again, the lower push rod driving portion 314 can be configured to move the lower push rod according to the control signal generated by the controller 500. The lower push rod 312 can be installed to be movable through a center hole 114 (also referred to herein as a first center hole) formed in (e.g., extending through) a middle portion of the lower platform 110 (e.g., a center portion of the lower platform 110 surrounding the center of the first surface 112) (e.g., extending through the middle portion). As shown, the center hole 114 can extend through the first surface 112 so that at least a portion of the first wafer W1 on the first surface 112 covers the center hole 114. The lower push rod 312 can be moved upward by the lower push rod driving portion 314 to apply pressure (e.g., contact and apply pressure) to the middle region W1-M of the first wafer W1, wherein the middle region W1-M can be the central portion of the first wafer W1 that is vertically aligned with the central hole 114 (e.g., overlaps with the central hole 114, covers the central hole 114, etc.). The lower push rod driving portion 314 can include a driving source such as a hydraulic cylinder, a pneumatic cylinder, a linear motor, a solenoid device, etc.

[0060] The upper push rod driving portion 324 (also referred to as an upper push rod driver) can be connected to and controlled by the controller 500 and can move the upper push rod 322 upward and downward. Again, the upper push rod driving portion 324 can be configured to move the upper push rod 322 based on a separate control signal generated by the controller 500 (which is separate from the control signal based on which the lower push rod driving portion 314 moves the lower push rod 312). The upper push rod 322 can be mounted to be movable (e.g., in a direction extending parallel to the longitudinal axis of the upper push rod 322) through a center hole 214 (also referred to herein as a second center hole) formed in (e.g., extending through) a middle portion of the upper platform 210 (e.g., a center portion of the upper platform 210 surrounding the center of the second surface 212). As shown, the center hole 214 can extend through the second surface 212 such that at least a portion of the second wafer W2 on the second surface 212 (e.g., held in contact with the second surface 212) covers the center hole 214. The upper push rod 322 can be moved downward by the upper push rod driving portion 324 to apply pressure (e.g., contact and apply pressure) to the middle region W2-M of the second wafer W2, wherein the middle region W2-M can be a central portion of the second wafer W2 that is vertically aligned with the center hole 214 (e.g., overlaps with the center hole 214, covers the center hole 214, etc.). Each of the upper push rod driving portion 324 and the lower push rod driving portion 314 can include a driving source (e.g., a driver) such as a hydraulic cylinder, a pneumatic cylinder, a linear motor, a solenoid device, etc.

[0061] For example, the controller 500 may control the protruding length B of the lower push rod 312 from the lower platform 110 and the protruding length T of the upper push rod 322 from the upper platform 210. As described later, the ratio of the protruding lengths of the lower push rod 312 and the upper push rod 322 may be controlled by the controller 500 to change according to the joint propagation.

[0062] In some example embodiments, a position detection sensor 400 may be provided in at least one of the lower chuck structure 100 and the upper chuck structure 200. The position detection sensor 400 may be configured to detect the bonding propagation position of the first wafer W1 and the second wafer W2. Again, the position detection sensor 400 may generate wafer position information indicating the position of one or more portions of the first wafer W1 and / or the second wafer W2 based on detecting the first wafer W1 and / or the second wafer W2 through one or more detection holes 216 (e.g., capturing an image of the first wafer W1 and / or the second wafer W2, detecting light reflected from an exposed portion of the first wafer W1 and / or the second wafer W2, and determining the flight time of the reflected light, etc.). The wafer position information may be processed (e.g., at the controller 500) to determine (e.g., detect) the bonding propagation position of the first wafer W1 and the second wafer W2. In some example embodiments, the position detection sensor 400 is configured to process sensor data generated at the position detection sensor 400 to determine a bond propagation position of the first wafer W1 and the second wafer W2, and provide information indicative of the bond propagation position to the controller 500. It will be understood that the wafer position information generated by the position detection sensor 400 may be generated based on detection of at least one of the first wafer W1 and the second wafer W2 by the position detection sensor 400, wherein such detection of the first wafer W1 and / or the second wafer W2 may include capturing an image of an exposed portion of the first wafer W1 and / or the second wafer W2 through the detection aperture 216, wherein such image may be processed to determine a position (e.g., a distance) of the exposed portion from the position detection sensor 400. Such detection may include emitting a light beam from the position detection sensor 400 toward at least one of the first wafer W1 and the second wafer W2, detecting reflection of at least a portion of the emitted light that is reflected by at least one of the first wafer W1 and the second wafer W2 back to the position detection sensor 400, and determining a portion of the exposed portion based on a determined time of flight of the light from the position detection sensor 400 to the exposed portion and back to the position detection sensor 400 via reflection. The position detection sensor 400 may include at least one vision camera configured to capture one or more images of the first wafer W1 and / or the second wafer W2, wherein such images may be processed to determine a bond propagation position of the first wafer W1 and / or the second wafer W2. Two vision cameras may be provided in the upper chuck structure 200.

[0063] In particular, at least Figure 2 As shown, the position detection sensor 400 may be a visual camera that can capture an image of the second wafer W2 through the detection hole 216 formed in the upper platform 210 to detect (e.g., generate sensor data (e.g., image) that can be processed to detect) deformation of the second wafer using a shading ratio. Figure 2 As shown, the detection hole 216 can extend through at least a portion of the upper platform 210 to extend through the second surface 212 and thereby expose at least a portion of the second wafer W2. The detection hole 216 can be formed to be spaced apart from the center of the upper platform 210 by a specific (or, alternatively, a predetermined) distance. For example, the detection hole 216 can be located within a range of 0.25R to 0.75R of a radius (R) from the center (210C) of the upper platform 210 to the outer edge (210E) of the upper platform 210, or within a range of 0.25R to 0.75R of a radius (R) from the center (110C) of the lower platform 110 to the outer edge (110E) of the lower platform 110. In the case where the wafer has a diameter of 300 mm, the detection hole 216 can have an inner radius of approximately 37.5 mm from the center of the upper platform 210 and an outer radius of approximately 112.5 mm. Therefore, a vision camera can be used to detect the bonding propagation position within a range between 37.5 mm and 112.5 mm from the center of the upper platform 210. The detection hole 216 can be located inside the second adsorption holes 230 (adsorption area) (e.g., between one or more second adsorption holes 230 and the central hole 214).

[0064] The position detection sensor 400 (e.g., a visual camera) can generate wafer position information based on detecting at least the exposed portion of the first wafer W1 and / or the second wafer W2 through the detection hole 216, and the wafer position information can be used to detect the bond propagation position of the second wafer W2 through the detection hole 216. The position detection sensor 400 can generate detected wafer position information based on the sensor data, wherein the detected wafer position information can indicate the position of the second wafer W2. The position detection sensor 400 (e.g., a visual camera) can output (e.g., send) the detected wafer position information (e.g., information indicating the detected bond propagation position) to the controller 500, and the controller 500 can calculate the bond propagation position of one or both of the first wafer W1 and the second wafer W2 based on the input wafer position information. It will be understood that the controller 500 can calculate the bond propagation position of a wafer (e.g., the first wafer W1) that is not directly imaged by the position detection sensor 400.

[0065] Therefore, it will be understood that the position detection sensor 400 can generate wafer position information that can indicate the bond propagation position of the first wafer W1 and / or the second wafer W2 based on directly monitoring the first wafer W1 and / or the second wafer W2 through the detection hole 216, wherein the bond propagation position can be the bond propagation position of the wafer that is not directly monitored by the position detection sensor 400 through the detection hole 216. Although Figure 2 The detection hole 216 in FIG is shown as a detection hole extending through the upper platform 210, but it will be understood that in some example embodiments, in addition to or instead of including such as Figure 2 As shown, the wafer bonding apparatus 70 may include one or more inspection holes 216 extending through the upper platform 210, and thus through the first surface 112, and further, in addition to or in lieu of the inspection holes 216. Figure 2 As shown, the wafer bonding device 70 may include one or more position detection sensors 400, which are located below the first surface 112 and are configured to detect the bonding propagation position of the first wafer W1 and / or the second wafer W2 through a detection hole 216 extending through the lower platform 110.

[0066] like Figure 5As shown, the controller 500 may be included in one or more instances of a processing circuit (e.g., hardware including a logic circuit), a hardware / software combination (e.g., a processor that executes software), or a combination thereof. The controller 500 may include one or more instances of a processing circuit (e.g., hardware including a logic circuit), a hardware / software combination (e.g., a processor that executes software), or a combination thereof, and / or the controller 500 may be implemented by one or more instances of a processing circuit (e.g., hardware including a logic circuit), a hardware / software combination (e.g., a processor that executes software), or a combination thereof. For example, the processing circuitry may more specifically include, but is not limited to, a processor 510. The processor 510 may include a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a system on a chip (SoC), a programmable logic unit, a microprocessor, an application specific integrated circuit (ASIC), etc. In some embodiments, the processing circuitry of the controller 500 may include a non-transitory computer-readable storage device 520 (e.g., memory) (e.g., a solid-state drive (SSD)) storing a program of instructions, and a processor 510 coupled to the storage device 520 (e.g., via a bus 505) and configured to execute the program of instructions to implement the functionality of the controller 500. Thus, the controller 500 as described herein may be interchangeably referred to as "processing circuitry," which may be configured to implement any and all of the functionality of the controller 500 as described herein.

[0067] like Figure 5 As shown, the controller 500 can be connected (e.g., communicatively coupled) to components of the wafer bonding apparatus 70 (e.g., the upper platform drive section 120, the lower platform drive section 220, the fluid control valve 132, the fluid control valve 232, the upper push rod drive section 314, the lower push rod drive section 324, and the vacuum pump 240) and configured to control the operation of the components of the wafer bonding apparatus 70. The controller 500 can receive position information from the position detection sensor 400 and determine (e.g., calculate) the bonding propagation position of the first wafer W1 and the second wafer W2 based on the position information. The controller 500 can apply (e.g., generate, transmit, etc.) control signals to the drive sections (e.g., the lower platform drive section 120, the vacuum pump 240, the lower push rod drive section 314, and the upper push rod drive section 324) to control the operation of the wafer bonding apparatus 70.

[0068] In some example embodiments, the wafer bonding apparatus 70 may further include a position detector (not shown) for aligning the wafers. The position detector may detect alignment keys, such as alignment keys for the first wafer W1 and the second wafer W2, through the holes 218 formed in the upper platform 210 and the holes formed in the lower platform 110, and the controller 500 may align the first wafer W1 and the second wafer W2 based on the detected information.

[0069] In the following, we will use Figure 2 The wafer bonding method performed by the wafer bonding equipment in the embodiment of the present invention is described.

[0070] Figure 6A and Figure 6B are cross-sectional views illustrating stages of a bonding process of a first wafer and a second wafer in a wafer bonding apparatus in some example embodiments.

[0071] Reference Figure 6A In order to perform the wafer bonding process, the first wafer W1 and the second wafer W2 may be held on the lower platform 110 and the upper platform 210 .

[0072] First, the first wafer W1 may be vacuum-adsorbed to be held on the first surface 112 of the lower platform 110 , and the second wafer W2 may be vacuum-adsorbed to be held on the second surface 212 of the upper platform 210 .

[0073] The lower push rod 312 can then be raised toward the upper platform 210 to apply pressure to the middle portion of the first wafer W1. As a result, the middle portion of the first wafer W1 can be separated from the first surface 112 of the lower platform 110, protruding further upward than the peripheral area. Simultaneously, the upper push rod 322 can be lowered toward the lower platform 110 to apply pressure to the middle portion of the second wafer W2. As a result, the middle portion of the second wafer W2 can be separated from the second surface 212 of the upper platform 210, protruding further downward than the peripheral area.

[0074] When the first wafer W1 bends upward so as to be concave upward and the second wafer W2 bends downward so as to be concave downward, the lower platform 110 may move upward so as to contact the first wafer W1 with the second wafer W2. If the middle portion of the first wafer W1 initially contacts the middle portion of the second wafer W2, bonding begins.

[0075] At the initial time of engagement, the lower push rod 312 may have a first protruding length B1 from the lower platform 110 , and the upper push rod 322 may have a first protruding length T1 .

[0076] In addition, at the initial time of bonding, the controller 500 can control the vacuum pump 240 so that vacuum pressure is applied (for example, supplied) to the first to third adsorption parts Z1, Z2, Z3 (Z1, Z2, Z3: on) of the upper platform 210 to form an adsorption area of ​​a first adsorption area in the peripheral area of ​​the upper platform 210, and the controller 500 can control the vacuum pump 240 so that vacuum pressure is applied to the third adsorption part Z3 of the lower platform 110 (Z3: on) to form an adsorption area of ​​a third adsorption area smaller than the first adsorption area in the peripheral area of ​​the lower platform 110. Therefore, at the initial time of bonding, a first adsorption area is formed in the peripheral area of ​​the upper platform 210, and a second adsorption area having an area smaller than the first adsorption area is formed in the peripheral area of ​​the lower platform 110, wherein, based on causing vacuum pressure to be supplied to a larger number of second adsorption holes 230 than the first adsorption holes 130, the first adsorption area is understood to be the total area of ​​the second adsorption holes 230 to which vacuum pressure is actively supplied from the vacuum pump 240, and the second adsorption area is understood to be the total area of ​​the first adsorption holes 130 to which vacuum pressure is actively supplied from the vacuum pump 240. It will be understood that, in some example embodiments, the control of applying vacuum pressure to certain adsorption portions of the upper platform 210 and / or the lower platform 110 may include controlling the valve position of one or more valves coupled to the vacuum pump 240 so as to control to which adsorption ducts 131, 231 the vacuum pressure is supplied. Figure 6A , the first to third adsorption portions Z1 , Z2 , and Z3 of the upper platform 210 may be indicated by hatching, and the third adsorption portion Z3 of the lower platform 110 may be indicated by hatching.

[0077] Reference Figure 6B , the bond between the first wafer W1 and the second wafer W2 can propagate radially outward, and then the first wafer and the second wafer can be joined. The bond propagation position can be detected by the position detection sensor 400. The bond propagation position at the peripheral area of ​​the first wafer W1 and the second wafer W2 can be detected by the position detection sensor 400. For example, in the case where the wafers have a diameter of 300 mm, the bond propagation position can be detected within a range between approximately 37.5 mm and approximately 110 mm from the center of the first wafer W1 and the second wafer W2.

[0078] The ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 can be controlled to change according to the progress of the bond. The ratio of the suction area of ​​the upper platform 210 to the suction area of ​​the lower platform 110 can be controlled to change according to the progress of the bond. Again, the controller 500 can be configured to change (e.g., by sending a control signal to the lower push rod driving portion 314 and / or the upper push rod driving portion 324) at least one of the ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 and the ratio of the suction area of ​​the upper platform 210 to the suction area of ​​the lower platform 110 based on the determined progress position of the bond of at least one of the first wafer W1 and the second wafer W2. The distance (G) between the lower platform 110 and the upper platform 210 can be controlled to change according to the progress of the bond. Again, the controller 500 can be configured to change (e.g., based on sending control signals to the lower platform drive portion 120 and / or the upper platform drive portion 220) the distance (G) between the lower platform 110 and the upper platform 210 based on the determined joint propagation position.

[0079] In the propagation of the engagement, the lower push rod 312 may have a second protrusion length B2 from the lower platform 110 , and the upper push rod 322 may have a second protrusion length T2 .

[0080] In addition, at the bonding propagation time, vacuum pressure may be applied to the third adsorption portion Z3 (Z3: on) of the upper platform 210 and the lower platform 110 to form an adsorption region of a third adsorption area in each of the peripheral regions of the upper platform 210 and the lower platform 110. Thus, at the bonding propagation time, a third adsorption region is formed in the peripheral region of the upper platform 210, wherein the third adsorption region has an area equal to or smaller than the second adsorption region, and a fourth adsorption region is formed in the peripheral region of the lower platform 110, wherein the fourth adsorption region has an area equal to the second adsorption region, wherein the third adsorption region is understood to be the total area of ​​the second adsorption holes 230 to which vacuum pressure is actively supplied from the vacuum pump 240, and the fourth adsorption region is understood to be the total area of ​​the first adsorption holes 130 to which vacuum pressure is actively supplied from the vacuum pump 240. It will be appreciated that in some example embodiments, controlling the application of vacuum pressure to certain adsorption portions of the upper platform 210 and / or the lower platform 110 may include controlling the valve position of one or more valves coupled to the vacuum pump 240 to control which adsorption conduits 131, 231 the vacuum pressure is supplied to. Figure 6B , the third adsorption portion Z3 of the upper platform 210 and the lower platform 110 is shown by hatching.

[0081] Hereinafter, a control method for compensating for asymmetry of the first wafer and the second wafer according to wafer bonding propagation will be described.

[0082] Figure 7 is a graph illustrating a change in a ratio of a protruding length of a lower push rod and a protruding length of an upper push rod according to engagement propagation, according to some example embodiments. Figure 8A and Figure 8B is a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of a protruding length of a lower push rod and a protruding length of an upper push rod at a bonding initial time. Figure 9A and Figure 9B is a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of a protruding length of a lower push pin and a protruding length of an upper push pin at a bonding propagation time. Figures 8A to 9B The curve W1 REVERSED in φ represents a curvature that is symmetrical to the curvature of the first wafer W1 .

[0083] Reference Figure 7 In some example embodiments, the ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 may be controlled to change according to the determined bonding propagation. For example, the ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 may be controlled (e.g., controlled based on a control signal sent from the controller 500) to gradually increase (e.g., continuously increase over time, increase at a constant or varying rate, increase in separate discrete step changes, etc.) according to the bonding propagation. The ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 may be gradually increased according to the bonding propagation to ensure symmetry at the bonding point of the first wafer and the second wafer, thereby reducing or minimizing (lowering) alignment errors.

[0084] Reference Figure 8A At the initial bonding time, when the ratio of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 is preset to 50:50, it can be seen that the curvatures at the bonding point between the first wafer W1 and the second wafer W2 are asymmetrical. Because the pressure direction of the upper push rod 322 is consistent with the direction of gravity, while the pressure direction of the lower push rod 312 is opposite to the direction of gravity, it can be understood that when the ratio of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 is preset to 50:50, the curvatures of the first wafer W1 and the second wafer W2 are asymmetrical.

[0085] Reference Figure 8B At the initial time of bonding, when the ratio of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 is preset to 40:60, so that at the initial time of bonding, the protruding length B1 of the lower push rod 312 is smaller than the protruding length T1 of the upper push rod 322, it can be seen that the curvatures at the bonding point of the first wafer W1 and the second wafer W2 are symmetrical to each other.

[0086] Therefore, at the bonding initial time, the ratio of the protruding length of the lower push rod 312 and the protruding length of the upper push rod 322 may be preset to be asymmetric to each other, thereby reducing or minimizing (lowering) the alignment error between the wafers.

[0087] Reference Figure 9A At the bonding propagation time after the bonding initial time, when the ratio of the protruding length of the lower pushing rod 312 to the protruding length of the upper pushing rod 322 is preset to 50:50, such that the protruding length B2 of the lower pushing rod 312 is equal to the protruding length T2 of the upper pushing rod 322 at the bonding propagation time, it can be seen that the curvatures at the bonding point of the first wafer W1 and the second wafer W2 are symmetrical to each other. In some example embodiments, at the bonding propagation time, the ratio of the protruding length of the lower pushing rod 312 to the protruding length of the upper pushing rod 322 may be preset to be greater than 50:50, such that the protruding length B2 of the lower pushing rod 312 is greater than the protruding length T2 of the upper pushing rod 322 at the bonding propagation time.

[0088] Reference Figure 9B , at the bonding propagation time, when the ratio of the protruding length of the lower pushing rod 312 to the protruding length of the upper pushing rod 322 is preset to 40:60, it can be seen that the curvatures at the bonding points of the first wafer W1 and the second wafer W2 are asymmetrical to each other.

[0089] Therefore, at the bonding termination time (e.g., the time when the bonding propagation has extended to the edges of the first wafer W1 and the second wafer W2, so that the first wafer W1 and the second wafer W2 are completely bonded to each other), the ratio of the protruding length of the lower push rod 312 and the protruding length of the upper push rod 322 can be preset to be symmetrical with each other, so that at the bonding termination time, the controller 500 makes the protruding length of the lower push rod 312 equal to the protruding length of the upper push rod 322, thereby reducing or minimizing the alignment error between the wafers. In some example embodiments, at the bonding termination time, the controller 500 may make the protruding length of the lower push rod 312 greater than the protruding length of the upper push rod 322.

[0090] Figure 10A is a graph illustrating a position of a lower platform according to joint propagation according to some example embodiments, Figure 10B is a graph illustrating protruding lengths of a lower push rod and an upper push rod according to engagement propagation according to some example embodiments. Figure 11 is a graph showing the distance between the lower platform and the upper platform at the joint propagation position.

[0091] Reference Figure 10A and Figure 10BIn some example embodiments, the distance (G) between the lower platform 110 and the upper platform 210 can be controlled to change according to the bond propagation. For example, the distance (G) between the lower platform 110 and the upper platform 210 can be controlled to gradually decrease (e.g., continuously decrease over time, decrease at a constant or varying rate, decrease in separate discrete step changes, etc.) according to the determined bond propagation position. The distance (G) between the lower platform 110 and the upper platform 210 can be gradually decreased according to the bond propagation, thereby reducing or minimizing (lowering) alignment errors.

[0092] Reference Figure 11 , the distance (G) between the lower platform 110 and the upper platform 210 may be reduced from 100 μm at the bonding initial time to 20 μm at the bonding propagation position.

[0093] At the bonding termination time, the vacuum adsorption of the upper platform 210 can be released to separate the second wafer W2 from the upper platform 210, so that the second wafer W2 falls onto the first wafer W1. Therefore, the bonding of the peripheral area of ​​the wafer (for example, R = 100mm to 150mm) can be terminated. In this case, when the second wafer W2 falls, alignment errors may occur due to the fluid dynamics. During the bonding propagation, the lower platform 110 can be gradually raised, thereby reducing the alignment errors that occur during the adsorption release at the bonding termination time.

[0094] Figure 12A 、 Figure 12B and Figure 12C is a graph illustrating curvatures of the first wafer and the second wafer according to a ratio of suction areas of the upper and lower platforms during bonding propagation.

[0095] Reference 12A to 12C The ratio of the adsorption areas of the upper platform 210 and the lower platform 110 may be controlled to change according to the bonding propagation (e.g., based on a control signal sent by the controller 500 to the vacuum pump 240). For example, the ratio of the adsorption areas of the upper platform 210 and the lower platform 110 may be controlled to gradually decrease according to the determined bonding propagation position (e.g., continuously decrease over time, decrease at a constant or varying rate, decrease in separate discrete step changes, etc.).

[0096] Figure 12A The upper right figure in FIG shows a case where vacuum pressure is applied to the third suction portion Z3 of the upper platform 210 (Z3: ON) and vacuum pressure is applied to the third suction portion Z3 of the lower platform 110 (Z3: ON) at the initial bonding time. In this case, it can be seen that the curvatures of the first wafer W1 and the second wafer W2 are asymmetrical with each other (here, the protruding length (B3) of the lower push rod 312 can be preset to be greater than the protruding length (T3) of the upper push rod 322).

[0097] Figure 12A The lower right figure in FIG shows a situation where vacuum pressure is applied to the first to third suction sections Z1, Z2, and Z3 of the upper platform 210 (Z1, Z2, and Z3: ON), and vacuum pressure is applied to the third suction section Z3 of the lower platform 110 (Z3: ON) at the initial stage of bonding. In this case, it can be seen that the curvatures of the first wafer W1 and the second wafer W2 are symmetrical with each other (here, the protruding length (B3) of the lower push rod 312 can be preset to be the same as the protruding length (T3) of the upper push rod 322).

[0098] Figure 12B The upper right figure in FIG shows a case where vacuum pressure is applied to the third suction portion Z3 of the upper platform 210 (Z3: ON) and vacuum pressure is applied to the third suction portion Z3 of the lower platform 110 (Z3: ON) at the middle of bonding. In this case, it can be seen that the curvatures of the first wafer W1 and the second wafer W2 are asymmetrical with each other (here, the protruding length (B4) of the lower push rod 312 can be preset to be greater than the protruding length (T4) of the upper push rod 322).

[0099] Figure 12B The lower right figure in FIG shows a situation in which vacuum pressure is applied to the second and third suction parts Z2 and Z3 of the upper platform 210 (Z2, Z3: ON), and vacuum pressure is applied to the third suction part Z3 of the lower platform 110 (Z3: ON) at the middle of bonding. In this case, it can be seen that the curvatures of the first wafer W1 and the second wafer W2 are symmetrical to each other (here, the protruding length (B4) of the lower push rod 312 can be preset to be the same as the protruding length (T4) of the upper push rod 322).

[0100] Figure 12C The right figure in FIG shows a case where vacuum pressure is applied to the third suction portion Z3 of the upper platform 210 (Z3: ON) and vacuum pressure is applied to the third suction portion Z3 of the lower platform 110 (Z3: ON) at the bonding propagation time. In this case, it can be seen that the curvatures of the first wafer W1 and the second wafer W2 are symmetrical to each other (here, the protruding length (B5) of the lower push rod 312 can be preset to be the same as the protruding length (T5) of the upper push rod 322).

[0101] In some example embodiments, at the initial time of bonding, the suction area in the peripheral region of the upper platform 210 may be preset to be larger than the suction area in the peripheral region of the lower platform 110, and as bonding progresses, the suction area in the peripheral region of the upper platform 210 may be controlled to be relatively reduced, while the suction area in the peripheral region of the lower platform 110 may be controlled to remain unchanged. Thus, asymmetric deformation between the first wafer W1 and the second wafer W2 as bonding progresses can be compensated.

[0102] In the following, the use of Figure 1 Wafer-to-wafer bonding method of a wafer bonding system in a wafer bonding system.

[0103] Figure 13 is a flowchart illustrating a wafer-to-wafer bonding method according to some example embodiments. Figure 14 It shows Figure 13 View of the wafer-to-wafer bonding method in Figure 2. Figure 15 It shows Figure 13 Flowchart of the bonding phase of the wafer-to-wafer bonding method.

[0104] Reference Figure 1 、 Figure 2 、 Figure 3 and Figures 13 to 15 , first, pre-processing may be performed on at least one of bonding surfaces of wafers to be bonded to each other ( S100 ).

[0105] In some example embodiments, the wafers W1 and W2 may be loaded into a chamber of a plasma processing apparatus 40 , plasma gas may be supplied onto the wafers W1 and W2 through a showerhead, and then plasma processing may be performed in the chamber.

[0106] The surface of the wafer that has been plasma treated can then be cleaned. DI water can be applied to the wafer surface using a spin coater in a cleaning device. DI water can clean the wafer surface and allow -OH groups to easily bond to the wafer surface, making it easy to create dangling bonds on the wafer surface.

[0107] Then, the pre-processed wafers W1 and W2 can be aligned (S110), and pressure can be applied to the middle parts of the wafers W1 and W2 so that the middle parts of the wafers protrude (S120). Then, the wafers are gradually combined from the middle part to the outer area so that the wafers W1 and W2 are combined (S130).

[0108] In some example embodiments, the pre-processed first wafer W1 and the second wafer W2 may be adsorbed and held on the lower platform 110 and the upper platform 210, respectively. The first wafer W1 may be vacuum-adsorbed by the first adsorption holes 130 formed in the lower platform 110. The second wafer W2 may be vacuum-adsorbed by the second adsorption holes 230 formed in the upper platform 210.

[0109] The lower push rod 312 can then be raised toward the upper platform 210 to apply pressure to the middle portion of the first wafer W1. As a result, the middle portion of the first wafer W1 can be separated from the first surface 112 of the lower platform 110, protruding upward further than the peripheral area. Simultaneously, the upper push rod 322 can be lowered toward the lower platform 110 to apply pressure to the middle portion of the second wafer W2. As a result, the middle portion of the second wafer W2 can be separated from the second surface 212 of the upper platform 210, protruding downward further than the peripheral area.

[0110] When the first wafer W1 bends upward so as to be concave upward and the second wafer W2 bends downward so as to be concave downward, the lower platform 110 may move upward so as to contact the first wafer W1 with the second wafer W2. If the middle portion of the first wafer W1 initially contacts the middle portion of the second wafer W2, bonding begins.

[0111] At the initial stage of engagement, the lower push rod 312 may have a first protrusion length B1 from the lower platform 110, and the upper push rod 322 may have a first protrusion length T1. For example, the ratio of the protrusion length of the lower push rod 312 to the protrusion length of the upper push rod 322 may be preset to 40:60. Here, the distance (G) between the lower platform 110 and the upper platform 210 may be maintained at approximately 100 mm.

[0112] In addition, at the initial stage of bonding, vacuum pressure may be applied to the first to third suction portions Z1, Z2, and Z3 of the upper platform 210 (Z1, Z2, and Z3: On), and vacuum pressure may be applied to the third suction portion Z3 of the lower platform 110 (Z3: On). Therefore, a suction region of the first suction area may be formed in the peripheral region of the upper platform 210, and a suction region of the third suction area smaller than the first suction area may be formed in the peripheral region of the lower platform 110.

[0113] Then, if Figure 15 As shown, at the bonding propagation time, the position detection sensor 400 may detect the bonding propagation positions of the first wafer W1 and the second wafer W2 ( S1302 ).

[0114] For example, the position detection sensor 400 may include a visual camera. The visual camera may detect the deformation of the second wafer W2 through the detection hole 216 formed in the upper platform 210. The detection hole 216 may be located within a range between 0.25R and 0.75R of a radius (R) from the center of the upper platform 210. In the case where the wafer has a diameter of 300 mm, the detection hole 216 may have an inner radius of approximately 40 mm and an outer radius of approximately 110 mm from the center of the upper platform 210. Therefore, a visual camera may be used to detect the bonding propagation position within a range between 40 mm and 110 mm from the center of the upper platform 210.

[0115] Then, a ratio (B / T) of the protruding length of the lower push rod 312 and the protruding length of the upper push rod 322 may be controlled to change according to the joint propagation ( S1304 ).

[0116] For example, the ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 can be controlled to gradually increase as the bonding progresses. The ratio (B / T) of the protruding length of the lower push rod 312 to the protruding length of the upper push rod 322 can be gradually increased as the bonding progresses to ensure symmetry at the bonding point of the first wafer W1 and the second wafer W2, thereby reducing or minimizing (lowering) alignment errors.

[0117] In addition, the ratio of the adsorption area of ​​the upper platform 210 and the adsorption area of ​​the lower platform 110 may be controlled to change according to the bonding propagation ( S1306 ).

[0118] For example, the ratio of the suction area in the peripheral region of the upper platform 210 to the suction area in the peripheral region of the lower platform 110 (upper platform suction area / lower platform suction area) can be controlled to gradually decrease according to the bonding propagation. The ratio of the suction area of ​​the upper platform 210 to the suction area of ​​the lower platform 110 can be gradually reduced according to the bonding propagation position to ensure symmetry at the bonding point of the first wafer W1 and the second wafer W2, thereby reducing or minimizing (lowering) alignment errors.

[0119] In addition, the distance (G) between the lower platform 110 and the upper platform 210 may be controlled to change according to the joint propagation ( S1308 ).

[0120] For example, the distance (G) between the lower platform 110 and the upper platform 210 may be controlled to gradually decrease according to the bonding propagation, thereby reducing or minimizing the alignment error.

[0121] In the joint propagation position, the lower push rod 312 may have a second protrusion length B2 from the lower platform 110, and the upper push rod 322 may have a second protrusion length T2. For example, in the joint propagation position, the ratio (B / T) of the protrusion length of the lower push rod 312 to the protrusion length of the upper push rod 322 may be preset to 50:50 or 60:40. In this case, the distance (G) between the lower platform 110 and the upper platform 210 may be maintained at approximately 20 mm.

[0122] In addition, at the joint propagation position, vacuum pressure may be applied to the third suction portion Z3 of the upper platform 210 and the third suction portion Z3 of the lower platform 110 (Z3: ON). Therefore, the suction area formed in the peripheral area of ​​the upper platform 210 and the suction area formed in the peripheral area of ​​the lower platform 110 may have the same suction area.

[0123] As described above, while the bonding of the upper wafer and the lower wafer propagates radially outward, the ratio (B / T) of the protruding length of the lower push rod 312 and the protruding length of the upper push rod 322, the ratio of the adsorption area of ​​the lower platform 110 and the adsorption area of ​​the upper platform 210, and the distance (G) between the lower platform 110 and the upper platform 210 can be changed.

[0124] Furthermore, at the bonding termination time, bonding propagation may have proceeded to the edges of the first wafer W1 and the second wafer W2 , so that the bonding process is completed and thus terminated ( S1310 ).

[0125] Therefore, while the bonding of the upper wafer and the lower wafer is propagating, the curvatures of the wafers at the bonding points can be controlled to be symmetrical with each other, thereby reducing or minimizing (lowering) the alignment error between the wafers, thereby improving the performance, reliability, structure, etc. of the semiconductor device formed by wafer bonding.

[0126] The wafer-to-wafer bonding system and wafer-to-wafer bonding method described above can be used to manufacture, for example, a semiconductor package or image sensor including a logic device and a memory device. For example, the semiconductor package can include a volatile memory device (such as a DRAM device and an SRAM device) or a non-volatile memory device (such as a flash memory device, a PRAM device, an MRAM device, a ReRAM device, etc.).

[0127] The above is an illustration of some example embodiments and should not be construed as limiting the same. Although some example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in some example embodiments without materially departing from the novel teachings and advantages of the present inventive concept. Therefore, all such modifications are intended to be included within the scope of some example embodiments as defined in the claims.

Claims

1. A wafer bonding apparatus comprising: Vacuum pump; a lower platform having a first surface and comprising a plurality of first suction holes in the first surface, wherein the lower platform is configured to vacuum-suction a first wafer onto the first surface based on vacuum pressure supplied from the vacuum pump to the plurality of first suction holes; an upper platform having a second surface and comprising a plurality of second suction holes in the second surface, wherein the upper platform is configured to vacuum-suction a second wafer onto the second surface based on vacuum pressure supplied from the vacuum pump to the plurality of second suction holes; a lower push rod movable through a first central hole in a middle portion of the lower platform to contact a middle region of the first wafer overlapping the first central hole and apply pressure to the middle region of the first wafer; an upper push rod movable through a second central hole in a middle portion of the upper platform to contact a middle region of the second wafer overlapping the second central hole and apply pressure to the middle region of the second wafer; a position detection sensor configured to generate wafer position information indicating a bond propagation position of the first wafer and the second wafer based on detecting at least one of the first wafer and the second wafer through a detection hole in at least one of the lower platform and the upper platform; a platform drive configured to move the lower platform and the upper platform relative to each other; a push rod driver configured to move the lower push rod and the upper push rod in a vertical direction; wherein the vacuum pump is configured to selectively supply vacuum pressure to both the plurality of first adsorption holes and the plurality of second adsorption holes; and a processing circuit configured to control operations of the stage driver, the push rod driver, and the vacuum pump, the processing circuit further configured to process the wafer position information to detect the bond propagation position, and the processing circuit further configured to perform at least one of the following: increasing the ratio of the protruding length of the lower push rod to the protruding length of the upper push rod over time according to the engagement propagation position so that at an engagement initial time, the protruding length of the lower push rod is smaller than the protruding length of the upper push rod, and at an engagement propagation time after the engagement initial time, the protruding length of the lower push rod is equal to or greater than the protruding length of the upper push rod, and The ratio of the adsorption area of ​​the upper platform to the adsorption area of ​​the lower platform is reduced over time according to the bonding propagation position, so that at the bonding initial time, a first adsorption zone is formed in the peripheral area of ​​the upper platform and a second adsorption zone with an area smaller than the first adsorption zone is formed in the peripheral area of ​​the lower platform, and at the bonding propagation time after the bonding initial time, a third adsorption zone with an area equal to or smaller than the second adsorption zone is formed in the peripheral area of ​​the upper platform, and a fourth adsorption zone with an area equal to the second adsorption zone is formed in the peripheral area of ​​the lower platform.

2. The wafer bonding apparatus according to claim 1, wherein: The position detection sensor includes a vision camera.

3. The wafer bonding apparatus according to claim 1, wherein: The detection hole is located within a range of 0.25R to 0.75R of a radius R from the center of the upper platform to the outer edge of the upper platform, or within a range of 0.25R to 0.75R of a radius R from the center of the lower platform to the outer edge of the lower platform.

4. The wafer bonding apparatus according to claim 1, wherein: The processing circuit is configured to change a distance between the lower platform and the upper platform according to the bond propagation position.

5. The wafer bonding apparatus according to claim 4, wherein: The processing circuit is configured to vary a distance between the lower platform and the upper platform over time based on the joint propagation position.

6. The wafer bonding apparatus according to claim 1, wherein: The plurality of first adsorption holes extend annularly around the center of the lower platform and are located at least 0.8R of a radius R from the center of the lower platform to the outer edge of the lower platform, and The plurality of second adsorption holes extend annularly around the center of the upper platform and are located at at least 0.8R of a radius R from the center of the upper platform to an outer edge of the upper platform.

7. A wafer bonding apparatus comprising: a lower platform having a first surface and comprising a plurality of first suction holes in the first surface, wherein the lower platform is configured to vacuum-suction the first wafer onto the first surface based on vacuum pressure supplied from a vacuum pump to the plurality of first suction holes; an upper platform having a second surface and comprising a plurality of second suction holes in the second surface, wherein the upper platform is configured to vacuum-suction a second wafer onto the second surface based on vacuum pressure supplied from the vacuum pump to the plurality of second suction holes; a lower push rod movable through a first central hole in a middle portion of the lower platform to contact a middle region of the first wafer overlapping the first central hole and apply pressure to the middle region of the first wafer; an upper push rod movable through a second central hole in a middle portion of the upper platform to contact a middle region of the second wafer overlapping the second central hole and apply pressure to the middle region of the second wafer; a position detection sensor configured to generate wafer position information indicating a bonding propagation position of the first wafer and the second wafer based on detecting at least one of the first wafer and the second wafer through a detection hole in at least one of the lower platform and the upper platform; and processing circuitry configured to process the wafer position information to detect the bond propagation position, the processing circuitry further configured to perform at least one of the following: controlling the protruding length of the lower push rod and the protruding length of the upper push rod according to the engagement propagation position so that at an engagement initial time, the protruding length of the lower push rod is smaller than the protruding length of the upper push rod, and at an engagement termination time after the engagement initial time, the protruding length of the lower push rod is equal to or greater than the protruding length of the upper push rod, and the ratio of the adsorption area of ​​the upper platform to the adsorption area of ​​the lower platform is reduced over time according to the bonding propagation position, so that at a bonding initial time, a first adsorption region is formed in a peripheral region of the upper platform, and a second adsorption region having an area smaller than the first adsorption region is formed in a peripheral region of the lower platform, and at a bonding propagation time after the bonding initial time, a third adsorption region having an area equal to or smaller than the second adsorption region is formed in the peripheral region of the upper platform, and a fourth adsorption region having an area equal to the second adsorption region is formed in the peripheral region of the lower platform, Wherein, the detection hole is located in the range of 0.25R to 0.75R of the radius R from the center of the upper platform to the outer edge of the upper platform, or in the range of 0.25R to 0.75R of the radius R from the center of the lower platform to the outer edge of the lower platform.

8. The wafer bonding apparatus according to claim 7, further comprising: a lower push rod driver configured to move the lower push rod according to a control signal generated by the processing circuit; as well as An upper push rod driver is configured to move the upper push rod according to a separate control signal generated by the processing circuit.

9. The wafer bonding apparatus according to claim 7, wherein: The position detection sensor includes a vision camera.

10. The wafer bonding apparatus according to claim 7, wherein: The processing circuit is configured to change a distance between the lower platform and the upper platform according to the bond propagation position.

11. The wafer bonding apparatus according to claim 10, wherein: The processing circuit is configured to vary a distance between the lower platform and the upper platform over time based on the joint propagation position.

12. The wafer bonding apparatus according to claim 7, wherein: The plurality of first adsorption holes extend annularly around the center of the lower platform and are located at least 0.8R of a radius R from the center of the lower platform to the outer edge of the lower platform, and The plurality of second adsorption holes extend annularly around the center of the upper platform and are located at at least 0.8R of a radius R from the center of the upper platform to an outer edge of the upper platform.

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