Wafer bonding equipment and bonding method for eliminating wafer warpage

Abstract

The present invention provides a wafer bonding device and bonding method for eliminating wafer warpage. The device includes: a photosensitive distance measuring device for determining the distance distribution between a first wafer and a second wafer and the photosensitive distance measuring device by receiving and feeding back optical signals, thereby obtaining first and second warpage distribution values ​​of the first and second wafers; and an adsorption device including multiple adsorption units for applying an adsorption force to the second wafer based on the adsorption value required to compensate for the second wafer, thereby quantitatively compensating for the deformation of the second wafer and maintaining the bonding surfaces of the first and second wafers relatively parallel. The present invention connects corresponding vacuum adsorption holes to different areas of a lower chuck based on the warpage distribution of the upper and lower wafers. By controlling the adsorption values ​​of the adsorption holes in different areas, the warpage of the bottom wafer is mechanically altered, maintaining the upper and lower wafers in a relatively parallel state. This significantly reduces bubbles and alignment errors during the force-bonding process, thereby improving the quality of the bonding process.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor equipment design, and in particular relates to a wafer bonding device and a bonding method for eliminating wafer warping. Background Art

[0002] Wafer bonding technology refers to the process of tightly combining two mirror-polished homogeneous or heterogeneous wafers through chemical and physical effects. After the wafers are bonded, the atoms on the interface react under the action of external forces to form covalent bonds that combine them into one, and the bonding interface reaches a specific bonding strength.

[0003] Bonding processes play a crucial role in MEMS and IC manufacturing. Traditional silicon-silicon bonding uses pattern recognition and camera alignment to align the upper and lower silicon wafers, followed by direct bonding. In actual operation, this model, due to factors such as wafer warpage, prevents gases from escaping from the wafer during the bonding process, impacting alignment accuracy. This typically results in increased bubbles and poor alignment accuracy, impacting product yield and, in extreme cases, even causing product failure.

[0004] The typical solution is to control the quality of incoming silicon wafers from the previous process, requiring that wafer warpage be kept within a certain range before bonding. However, this creates a significant bottleneck for other processes, making many structures impossible to build and significantly increasing production costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a wafer bonding device and method for eliminating wafer warpage, which is used to solve the problems of bubbles and alignment accuracy generated during the bonding process due to different warpages of incoming wafers in the prior art.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a wafer bonding device for eliminating wafer warpage, the wafer bonding device comprising: a photosensitive ranging device, arranged above a first wafer and a second wafer, for determining the distance distribution between the top surface of the first wafer and the photosensitive ranging device, and determining the distance distribution between the top surface of the second wafer and the photosensitive ranging device through reception and feedback of optical signals, thereby obtaining a first warpage distribution value of the first wafer and a second warpage distribution value of the second wafer, wherein the second wafer is located above the first wafer; an adsorption device, arranged below the second wafer, the adsorption device comprising a plurality of adsorption units, the adsorption device applying an adsorption force from the bottom of the second wafer to the second wafer according to the adsorption value to be compensated for the second wafer, so as to quantitatively compensate for the deformation of the second wafer, so that the bonding surfaces of the first wafer and the second wafer remain relatively parallel.

[0007] Optionally, the photosensitive ranging device is also used to obtain the deformation amount that needs to be changed in each area of ​​the second wafer based on the first warpage distribution value and the second warpage distribution value of the second wafer; the adsorption device controls the adsorption force of the corresponding area based on the deformation amount that needs to be changed, so as to quantitatively compensate for the deformation amount of the second wafer, so that the bonding surfaces of the first wafer and the second wafer remain relatively parallel.

[0008] Optionally, the adsorption force is obtained by the following formula: F=k△x+B; wherein F is the adsorption force, k is the elastic constant of the second wafer, and B is a fixed constant.

[0009] Optionally, the adsorption device includes a vacuum suction cup, and the surface of the vacuum suction cup has multiple adsorption holes. The adsorption force of the adsorption holes is adjusted by setting the vacuum degree of the vacuum suction cup and the aperture of the adsorption holes, wherein the magnitude of the adsorption force is positively correlated with the vacuum degree and negatively correlated with the aperture of the adsorption holes.

[0010] Optionally, the vacuum suction cup includes a plurality of vacuum cavities, each vacuum cavity is correspondingly provided with one or more adsorption holes, and the vacuum degree in each vacuum cavity is independently adjustable to control the adsorption force of the corresponding area.

[0011] Optionally, the shape of the adsorption hole includes one of a circular hole, an arc hole and a ring hole.

[0012] Optionally, the wafer bonding equipment further includes a pin component, which is disposed above the first wafer and is used to apply point pressure to the first wafer and the second wafer to pre-bond the first wafer and the second wafer.

[0013] The present invention also provides a wafer bonding method for eliminating wafer warpage, comprising: providing a wafer bonding device for eliminating wafer warpage as described in any one of the above items; placing a first wafer in the wafer bonding device, and determining the distance distribution between the top surface of the first wafer and the photosensitive ranging device by receiving and feeding back optical signals based on a photosensitive ranging device, thereby obtaining a first warpage distribution value of the first wafer; placing a second wafer above the first wafer in the wafer bonding device, and determining the distance distribution between the top surface of the second wafer and the photosensitive ranging device by receiving and feeding back optical signals based on a photosensitive ranging device, thereby obtaining a second warpage distribution value of the second wafer; obtaining a deformation amount that needs to be changed in each area of ​​the second wafer based on the first warpage distribution value and the second warpage distribution value of the second wafer; and applying an adsorption force from the bottom of the second wafer to the second wafer based on the adsorption value that needs to be compensated for the second wafer, so as to quantitatively compensate for the deformation amount of the second wafer, so that the bonding surfaces of the first wafer and the second wafer remain relatively parallel.

[0014] Optionally, the adsorption device includes a vacuum suction cup, which includes multiple vacuum cavities, each vacuum cavity contains one or more adsorption holes, and the vacuum degree in each vacuum cavity is independently adjustable. The adsorption force of the adsorption hole is adjusted by setting the vacuum degree of the vacuum cavity and the aperture of the adsorption hole.

[0015] Optionally, the bonding method further comprises the step of applying point pressure to the first wafer and the second wafer using a pin component to pre-bond the first wafer and the second wafer.

[0016] As described above, the wafer bonding apparatus and method for eliminating wafer warpage of the present invention have the following beneficial effects:

[0017] The present invention connects corresponding vacuum adsorption holes to different areas of the lower chuck according to the warpage distribution of the upper and lower wafers. By controlling the adsorption values ​​of the adsorption holes in different areas, the warpage condition of the bottom wafer is mechanically changed, so that the upper and lower wafers are in a relatively parallel state. During the force bonding process of the wafers, bubbles and alignment accuracy errors are greatly reduced, thereby improving the quality of the bonding process.

[0018] The present invention installs a photosensitive ranging device inside the bonding machine, and connects different adsorption holes in different areas of the lower chuck. The warpage distribution of the wafer is simulated and calculated inside the machine, and the adsorption value is changed accordingly during the bonding process. It has good compatibility with the bonding machine and can also be widely used in multi-layer bonding, with good practical application value.

[0019] The use of the equipment and method of the present invention can completely solve the problem of wafer warping during the bonding process and can effectively reduce production costs and process complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a structural schematic diagram of a wafer bonding device for eliminating wafer warpage according to an embodiment of the present invention.

[0021] Figure 2 Shown is a structural schematic diagram of an adsorption device of a wafer bonding device for eliminating wafer warpage according to an embodiment of the present invention.

[0022] Figure 3 A schematic diagram showing the principle of obtaining a wafer warpage distribution value by a wafer bonding device for eliminating wafer warpage according to an embodiment of the present invention is shown.

[0023] Figure 4 It is a schematic diagram showing the principle of quantitatively compensating the deformation of the wafer by the wafer bonding equipment for eliminating wafer warpage according to an embodiment of the present invention.

[0024] Component number description

[0025] 101 Photosensitive ranging device

[0026] 102 adsorption device

[0027] 103 First Wafer

[0028] 104 Second Wafer

[0029] 105 The second wafer after quantitatively compensating for deformation

[0030] 106 adsorption holes

[0031] 1061 round hole

[0032] 1062 annular hole

[0033] 1063 Arc Hole DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] For example, when describing the embodiments of the present invention, cross-sectional views of device structures may be partially enlarged to scale for ease of explanation. Furthermore, these schematic views are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual manufacturing, three-dimensional dimensions, including length, width, and depth, should be included.

[0036] For convenience, spatially relative terms such as "under," "below," "below," "below," "above," and "on" may be used herein to describe the relationship of one element or feature to other elements or features illustrated in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation in addition to the orientation depicted in the drawings. Additionally, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0037] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature is formed between the first and second features, such that the first and second features may not be in direct contact.

[0038] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0039] The traditional bonding machine's mode of reducing warpage generally uses ultra-high pressure to change the warpage value of the wafer, but this mode will cause the wafer itself to be deformed under pressure, affecting the bonding accuracy. The purpose of the present invention is to install a photosensitive ranging device 101 inside the bonding machine to simulate the warpage and distribution of the wafer during the bonding process, and then feed back to the bonding machine. According to the warpage distribution of the upper and lower wafers, the bonding machine gives different adsorption strengths to the bottom wafer in different areas during the bonding process, quantitatively changing the warpage value of the bottom wafer to make it close to the warpage distribution of the top wafer, and finally keeping the two wafers in a relatively parallel distribution.

[0040] This method measures the warpage distribution of two wafers and calculates the required deformation of the bottom wafer. For wafers manufactured using the same process, the vertical strain approximates a linear relationship. This is then programmed into the bonding machine's production program to compensate for the varying warpage of incoming wafers, maintaining a level surface throughout the bonding process and improving bonding quality.

[0041] like Figure 1 As shown, this embodiment provides a wafer bonding device for eliminating wafer warpage, and the wafer bonding device includes: a photosensitive ranging device 101 and an adsorption device 102.

[0042] The photosensitive ranging device 101 is arranged above the first wafer 103 and the second wafer 104, and is used to determine the distance distribution between the top surface of the first wafer 103 and the photosensitive ranging device 101, and determine the distance distribution between the top surface of the second wafer 104 and the photosensitive ranging device 101 through the reception and feedback of optical signals, thereby obtaining a first warpage distribution value of the first wafer 103 and a second warpage distribution value of the second wafer 104, and the second wafer 104 is located above the first wafer 103.

[0043] For example, the photosensitive ranging device 101 includes a photosensitive ranging chuck, which emits light to the wafer below and then reflects it. When the wafer warps, there are differences in the reflected light signals at different positions. The photosensitive ranging chuck determines the distance distribution between the top surface of the wafer and the photosensitive ranging chuck based on the difference, thereby obtaining the warpage distribution value of the wafer, such as Figure 3 shown.

[0044] During application, it is only necessary to fix the photosensitive ranging chuck on the inside of the wafer bonding device through detachable connectors such as screws. It can be powered by the power supply line of the wafer bonding device, or it can be powered by its own battery. It can be connected to the adsorption device 102 in a wired or wireless manner to achieve signal connection between it and the adsorption device 102.

[0045] Furthermore, in this embodiment, the photosensitive ranging device 101 is also used to obtain the deformation amount that needs to be changed in each area of ​​the second wafer 104 based on the first warpage distribution value and the second warpage distribution value of the second wafer 104.

[0046] like Figures 1 to 4 As shown, the adsorption device 102 is arranged below the second wafer 104. The adsorption device 102 includes multiple adsorption units. The adsorption device 102 applies adsorption force from the bottom of the second wafer 104 to the second wafer 104 according to the adsorption value that needs to be compensated for the second wafer 104, so as to quantitatively compensate for the deformation of the second wafer 104, and obtain the second wafer 105 after the quantitative compensation of the deformation, so that the bonding surfaces of the first wafer 103 and the second wafer 104 remain relatively parallel.

[0047] In this embodiment, the adsorption device 102 controls the adsorption force of the corresponding area based on the deformation amount that needs to be changed fed back by the photosensitive ranging device 101, so as to quantitatively compensate for the deformation amount of the second wafer 104, so that the bonding surfaces of the first wafer 103 and the second wafer 104 remain relatively parallel.

[0048] In this embodiment, the adsorption force is calculated using the following formula: F = kΔx + B, where F is the adsorption force, k is the elastic constant of the second wafer 104, and B is a fixed constant. For wafers manufactured using the same process, the vertical strain approximately satisfies a linear relationship. By programming the bonding equipment accordingly, targeted compensation can be made for the varying warpage of incoming wafers, ensuring they remain level throughout the bonding process and improving bonding quality.

[0049] like Figure 1 and Figure 2 As shown, the adsorption device 102 includes a vacuum suction cup, and a plurality of adsorption holes 106 are provided on the surface of the vacuum suction cup. The adsorption force of the adsorption holes 106 is adjusted by setting the vacuum degree of the vacuum suction cup and the aperture of the adsorption holes 106, wherein the magnitude of the adsorption force is positively correlated with the vacuum degree and negatively correlated with the aperture of the adsorption holes 106.

[0050] To further adapt to the warpage distribution of wafers in different regions, in this embodiment, the vacuum chuck includes multiple vacuum chambers, each containing one or more suction holes 106. The vacuum level within each vacuum chamber is independently adjustable to control the suction force in the corresponding region. This example applies different suction strengths to the bottom wafer in different regions, quantitatively changing the warpage value of the bottom wafer to make it closer to the warpage distribution of the top wafer, ultimately maintaining a relatively parallel distribution between the two wafers.

[0051] Since wafer warping is generally more severe at the edges of the wafer and less severe in the middle area, in a specific implementation process, the density of the adsorption holes 106 of the adsorption device 102 corresponding to the edge area of ​​the second wafer 104 is greater than the density of the adsorption holes 106 located in the middle area of ​​the second wafer 104, and the aperture of the adsorption holes 106 of the adsorption device 102 corresponding to the edge area of ​​the second wafer 104 is smaller than the aperture of the adsorption holes 106 located in the middle area of ​​the second wafer 104.

[0052] The shape of the adsorption hole 106 includes one of a circular hole 1061, an arc hole 1063 and an annular hole 1062. Figure 2 As shown, of course, the shape of the adsorption hole 106 can also be a rectangle, triangle, rhombus, ellipse, etc., and is not limited to the examples listed here. In this embodiment, the adsorption hole 106 located inside the adsorption device 102 is a circular hole 1061, the adsorption hole 106 located in the middle of the adsorption device 102 is an annular hole 1062, and the adsorption hole 106 located at the edge of the adsorption device 102 is an arc hole 1063. Furthermore, the circular hole 1061 inside the adsorption device 102, the annular hole 1062 in the middle, and the arc hole 1063 at the edge are all provided with independent vacuum chambers, so that the adsorption force of the adsorption holes 106 in each area can be independently adjusted. This configuration is more widely applicable to improving wafer warpage and can cope with deformation compensation for most wafer warpages. Therefore, in most cases, deformation compensation for wafer warpage can be achieved without replacing the adsorption device 102, which can effectively save costs.

[0053] In this embodiment, the wafer bonding equipment further includes a pin component disposed above the first wafer 103 for applying point pressure to the first wafer 103 and the second wafer 104 to pre-bond the first wafer 103 and the second wafer 104 .

[0054] like Figures 1 to 4As shown, this embodiment also provides a wafer bonding method for eliminating wafer warpage, comprising: providing a wafer bonding device for eliminating wafer warpage as described in any one of the above; placing a first wafer 103 in the wafer bonding device, and based on the photosensitive ranging device 101, determining the distance distribution between the top surface of the first wafer 103 and the photosensitive ranging device 101 by receiving and feeding back an optical signal, thereby obtaining a first warpage distribution value of the first wafer 103; placing a second wafer 104 above the first wafer 103 in the wafer bonding device, and based on the photosensitive ranging device 101, determining the distance distribution between the top surface of the first wafer 103 and the photosensitive ranging device 101 by receiving and feeding back an optical signal, thereby obtaining a first warpage distribution value of the first wafer 103; placing a second wafer 104 above the first wafer 103 in the wafer bonding device, and based on the photosensitive ranging device 101, determining the distance distribution between the top surface of the first wafer 103 and the photosensitive ranging device 101 by receiving and feeding back an optical signal and feedback, determine the distance distribution between the top surface of the second wafer 104 and the photosensitive ranging device 101, thereby obtaining the second warpage distribution value of the second wafer 104; according to the first warpage distribution value and the second warpage distribution value of the second wafer 104, obtain the deformation amount that needs to be changed in each area of ​​the second wafer 104; the adsorption device 102 applies adsorption force from the bottom of the second wafer 104 to the second wafer 104 according to the adsorption value that needs to be compensated for the second wafer 104, so as to quantitatively compensate for the deformation amount of the second wafer 104, so that the bonding surfaces of the first wafer 103 and the second wafer 104 remain relatively parallel.

[0055] For example, the adsorption device 102 includes a vacuum suction cup, which includes multiple vacuum cavities, each vacuum cavity contains one or more adsorption holes 106, and the vacuum degree in each vacuum cavity is independently adjustable. The adsorption force of the adsorption hole 106 is adjusted by setting the vacuum degree of the vacuum cavity and the aperture of the adsorption hole 106.

[0056] In this embodiment, the bonding method further comprises the step of applying a point pressure to the first wafer 103 and the second wafer 104 using a pin component to pre-bond the first wafer 103 and the second wafer 104. After the pre-bonding is completed, the pre-bonded wafers are transported out of the wafer bonding equipment via a conveyor.

[0057] As described above, the wafer bonding apparatus and method for eliminating wafer warpage of the present invention have the following beneficial effects:

[0058] The present invention connects corresponding vacuum adsorption holes to different areas of the lower chuck according to the warpage distribution of the upper and lower wafers. By controlling the adsorption values ​​of the adsorption holes in different areas, the warpage condition of the bottom wafer is mechanically changed, so that the upper and lower wafers are in a relatively parallel state. During the force bonding process of the wafers, bubbles and alignment accuracy errors are greatly reduced, thereby improving the quality of the bonding process.

[0059] The present invention installs a photosensitive ranging device inside the bonding machine, and connects different adsorption holes in different areas of the lower chuck. The warpage distribution of the wafer is simulated and calculated inside the machine, and the adsorption value is changed accordingly during the bonding process. It has good compatibility with the bonding machine and can also be widely used in multi-layer bonding, with good practical application value.

[0060] The use of the equipment and method of the present invention can completely solve the problem of wafer warping during the bonding process and can effectively reduce production costs and process complexity.

[0061] Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0062] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A wafer bonding device for eliminating wafer warpage, characterized in that: The wafer bonding equipment includes: a photosensitive ranging device, disposed above the first wafer and the second wafer, for determining the distance distribution between the first wafer and the photosensitive ranging device, and determining the distance distribution between the second wafer and the photosensitive ranging device, by receiving and feeding back optical signals, thereby obtaining a first warpage distribution value of the first wafer and a second warpage distribution value of the second wafer, and obtaining a deformation amount required to be changed in each area of ​​the second wafer based on the first warpage distribution value and the second warpage distribution value of the second wafer, wherein the second wafer is located above the first wafer; a suction device disposed below the second wafer, the suction device comprising a vacuum suction cup having a plurality of suction holes on a surface of the vacuum suction cup, the vacuum suction cup further comprising a plurality of vacuum cavities, each of the vacuum cavities comprising one or more suction holes, and the vacuum level within each vacuum cavity being independently adjustable; the suction device applying a suction force from the bottom of the second wafer to the second wafer based on the desired deformation amount of each region of the second wafer, and controlling the suction force of the corresponding region by adjusting the vacuum level within the vacuum cavity corresponding to each region, thereby quantitatively compensating for the deformation amount of each region of the second wafer, and maintaining the bonding surfaces of the first wafer and the second wafer relatively parallel; The adsorption force is obtained by the following formula: F=k△x+B; Wherein, F is the adsorption force, k is the elastic constant of the second wafer, and B is a fixed constant.

2. The wafer bonding apparatus for eliminating wafer warpage according to claim 1, wherein: The adsorption force of the adsorption hole is adjusted by setting the aperture of the adsorption hole, wherein the magnitude of the adsorption force is positively correlated with the vacuum degree and negatively correlated with the aperture of the adsorption hole.

3. The wafer bonding apparatus for eliminating wafer warpage according to claim 2, wherein: The shape of the adsorption hole includes one of a circular hole, an arc hole and a ring hole.

4. The wafer bonding apparatus for eliminating wafer warpage according to claim 1, wherein: The wafer bonding equipment further includes a pin component, which is disposed above the first wafer and is used to apply point pressure to the first wafer and the second wafer so as to pre-bond the first wafer and the second wafer.

5. A wafer bonding method for eliminating wafer warpage, characterized in that: The wafer bonding method comprises: Providing a wafer bonding device for eliminating wafer warpage as claimed in any one of claims 1 to 4; Placing a first wafer in the wafer bonding device, and determining a distance distribution between the first wafer and the photosensitive distance measuring device by receiving and feeding back an optical signal based on the photosensitive distance measuring device, thereby obtaining a first warpage distribution value of the first wafer; Placing a second wafer above the first wafer in the wafer bonding equipment, and determining a distance distribution between the second wafer and the photosensitive ranging device by receiving and feeding back an optical signal based on the photosensitive ranging device, thereby obtaining a second warpage distribution value of the second wafer; Obtaining a deformation amount required to be changed in each region of the second wafer according to the first warpage distribution value and the second warpage distribution value of the second wafer; The adsorption device applies adsorption force from the bottom of the second wafer to the second wafer according to the adsorption value required to be compensated for the second wafer, so as to quantitatively compensate for the deformation of the second wafer and keep the bonding surfaces of the first wafer and the second wafer relatively parallel.

6. The wafer bonding method for eliminating wafer warpage according to claim 5, wherein: The adsorption force of the adsorption holes is adjusted by setting the pore diameter of the adsorption holes.

7. The wafer bonding method for eliminating wafer warpage according to claim 5, wherein: The method further includes the step of applying point pressure to the first wafer and the second wafer using a pin component to pre-bond the first wafer and the second wafer.

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