Wafer bonding apparatus

Abstract

The application provides a wafer bonding device, and relates to the technical field of integrated circuit packaging. The wafer bonding device comprises an upper wafer adsorption table, the upper wafer adsorption table comprises an adsorption disc at the bottom, a plurality of adsorption units capable of working independently and a plurality of heating units capable of working independently are arranged on the adsorption disc, the adsorption units and the heating units are distributed in a ring shape respectively, and the plurality of adsorption units and the plurality of heating units are alternately and spacedly arranged from the center of the upper wafer adsorption table to the outer periphery. The application can improve the stress concentration of the wafer in the bonding process, and then the peeling phenomenon can be avoided.

Description

Technical Field

[0001] This invention relates to the technical field of integrated circuit packaging, and more specifically, to a wafer bonding device. Background Technology

[0002] Wafer bonding is a process that combines two or more wafers together using physical or chemical methods to form a single semiconductor device. During bonding, the atoms at the interface are subjected to external forces, causing them to react and form covalent bonds, thus achieving a specific bonding strength at the bonding interface.

[0003] Bonding equipment is the core of a complete hybrid bonding process. The bonding head within the equipment needs to provide precise bonding force and have accurate physical field control capabilities for the bonding process. Currently, bonding heads typically use adsorption elements to fix the wafer to complete the bonding. Precise temperature and adsorption force control are crucial for achieving high-quality bonding. In related technologies, the two wafers are generally heated continuously throughout the bonding process. However, continuous heating of the bonded area can lead to stress concentration on the wafer, resulting in delamination of the bonded area and affecting the bonding effect. Summary of the Invention

[0004] The problem solved by this invention is to improve the stress concentration and subsequent peeling phenomenon that occurs during the bonding process of wafers.

[0005] To address the aforementioned problems, the present invention provides a wafer bonding apparatus, which includes an upper wafer adsorption stage. The upper wafer adsorption stage includes an adsorption disk located at the bottom. The adsorption disk is provided with multiple adsorption units and multiple heating units that can operate independently. The adsorption units and the heating units are respectively arranged in a ring shape, and the multiple adsorption units and the heating units are arranged alternately from the center of the upper wafer adsorption stage to the outer periphery.

[0006] Optionally, each of the adsorption units includes a plurality of adsorption pores spaced apart along the circumferential direction, and each of the heating units includes a plurality of heating blocks spaced apart along the circumferential direction.

[0007] Optionally, the wafer bonding apparatus further includes an annular air pump, which is arranged around the outer periphery of the upper wafer adsorption stage, and each adsorption unit is connected to the annular air pump.

[0008] Optionally, the upper wafer adsorption stage is provided with a plurality of first air channels, and the plurality of first air channels are arranged in a one-to-one correspondence with a plurality of adsorption units. Each adsorption unit is connected to the annular air pump through the first air channel.

[0009] Each of the first airways is provided with an airway control valve, which is used to control the opening and closing of the corresponding first airway.

[0010] Optionally, the wafer bonding apparatus further includes a heating power supply and multiple current switches, with each current switch corresponding to one of the multiple heating units. The heating power supply is electrically connected to each heating unit, and each current switch is used to control the current flow between the heating power supply and the corresponding heating unit.

[0011] Optionally, it also includes a bonding drive assembly and a lower wafer support stage, wherein the upper wafer adsorption stage and the lower wafer support stage are disposed opposite each other, and the bonding drive assembly is used to drive the upper wafer adsorption stage and the lower wafer support stage to move closer to each other.

[0012] Optionally, the wafer bonding apparatus further includes a pusher assembly for pushing the wafer center downwards.

[0013] Optionally, the propulsion assembly includes a thrust motor and a propulsion rod, one end of which is connected to the thrust motor, and the other end of which passes through the center of the upper wafer adsorption stage from top to bottom.

[0014] Optionally, the wafer bonding apparatus further includes a force sensor disposed on the push rod for real-time detection of the magnitude of the wafer bonding force.

[0015] Optionally, the wafer bonding equipment further includes a control system, which is electrically connected to the gas duct control valve and the current switch, respectively.

[0016] The control system is used to control the opening and closing of multiple airway control valves and current switches, so that multiple adsorption units and heating units are closed sequentially from the center of the upper wafer adsorption stage to the outer periphery.

[0017] The beneficial effects of the wafer bonding apparatus of the present invention are:

[0018] This invention integrates multiple independently operating adsorption units and heating units into a wafer bonding apparatus. In actual operation, the upper wafer adsorption stage picks up one wafer using the adsorption unit at the bottom, activates its surface using the heating unit, and then bonds it to another wafer. This invention arranges the adsorption and heating units in an alternating ring pattern, satisfying temperature control while conforming to the circular propagation of bonding waves from the wafer center outwards. During the bonding process, the adsorption unit at the center stops adsorption first, allowing the centers of the two wafers to contact first, and the heating unit also stops operating, completing bonding at the center first. Then, as the bonding process continues, the adsorption units from the center outwards sequentially stop adsorption, and the heating units sequentially stop heating, until the two wafers are completely bonded. This facilitates the zoned adjustment of adsorption and heating functions. The sequential pause of the adsorption unit allows the wafer to bond sequentially from the center to the outer periphery, thus fully eliminating air bubbles. The sequential pause of the heating unit ensures that the non-bonded areas of the wafer are fully heated and activated before bonding, while also avoiding overheating of the bonding areas, thereby preventing stress concentration and subsequent peeling. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the wafer bonding equipment in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the adsorption disk in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal structure of the upper wafer adsorption stage in an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the operation of the control system in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Upper wafer adsorption stage; 11. Adsorption plate; 111. Through hole; 12. Adsorption unit; 121. Adsorption vent; 13. Heating unit; 131. Heating block; 14. First air channel; 15. Second air channel; 16. Air channel control valve; 2. Ring air pump; 3. Heating power supply; 4. Current switch; 5. Bonding drive assembly; 6. Lower wafer support stage; 7. Push assembly; 71. Thrust motor; 72. Push rod; 8. Force sensor; 9. Mounting bracket; 10. Control system. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0026] In the attached diagram, the Z-axis represents the vertical direction, i.e., up and down, with the positive direction of the Z-axis representing upward and the negative direction representing downward. The X-axis represents the horizontal direction and is designated as front and back, with the positive direction of the X-axis representing the front and the negative direction representing the back. The Y-axis represents the left and right position, with the positive direction of the Y-axis representing the left and the negative direction representing the right. It should be noted that the aforementioned representations of the Z, Y, and X axes are merely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0027] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0028] It should be noted that the terms "one" and "more" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0029] Wafer bonding typically begins at the center of the two wafers and gradually diffuses outwards, with the centers of the two wafers contacting first. This facilitates the removal of gas between the wafers, preventing bubble formation at the bonding interface. During wafer bonding, the bonded area is called the bonding region, and the unbonded area is called the non-bonded region. Normally, the bonding region does not require further heating, while the non-bonded region requires continuous heating to activate the surfaces of the two wafers and promote the formation of intermolecular forces. However, currently, the two intact wafers are generally continuously heated throughout the bonding process. This leads to stress concentration in the bonding region, resulting in delamination.

[0030] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a wafer bonding apparatus. (Refer to...) Figure 1 and Figure 2 As shown, the wafer bonding equipment includes an upper wafer adsorption stage 1, which includes an adsorption disk 11 located at the bottom. The adsorption disk 11 is provided with multiple adsorption units 12 and multiple heating units 13 that can work independently. The adsorption units 12 and heating units 13 are arranged in a ring shape, and the multiple adsorption units 12 and heating units 13 are arranged alternately from the center of the upper wafer adsorption stage 1 to the outer periphery.

[0031] This invention integrates an adsorption unit 12 and a heating unit 13 into a wafer bonding apparatus. During operation, the upper wafer adsorption stage 1 picks up one wafer using the adsorption unit 12 at the bottom, activates its surface using the heating unit 13, and then bonds it to another wafer. This invention sets the adsorption unit 12 and heating unit 13 in a ring shape, arranging multiple ring-shaped adsorption units 12 and heating units 13 alternately from the center outwards. This not only satisfies temperature control but also better conforms to the law of bonding waves propagating in a ring from the wafer center outwards. In the specific bonding process, the adsorption unit 12 at the center stops adsorption first, allowing the centers of the two wafers to contact first. Simultaneously, the heating unit 13 at the center also stops working, ensuring that bonding at the center is completed first. Then, as the bonding process continues, the adsorption units 12 sequentially stop adsorption from the center outwards, and the heating units 13 sequentially stop heating, until the two wafers are completely bonded. This facilitates the zoned adjustment of adsorption and heating functions. The sequential pauses of the adsorption unit 12 facilitate the sequential bonding of the wafer from the center to the outer periphery, thereby fully eliminating air bubbles. The sequential pauses of the heating unit 13 ensure that the non-bonded areas of the wafer are fully heated and activated before bonding and that heating is stopped after bonding, thus avoiding overheating of the bonding areas and preventing stress concentration that could lead to delamination.

[0032] In some alternative embodiments, refer to Figure 2As shown, each adsorption unit 12 includes a plurality of adsorption pores 121 evenly spaced along the circumferential direction. Correspondingly, each heating unit 13 includes a plurality of heating blocks 131 evenly spaced along the circumferential direction.

[0033] In this embodiment of the invention, each adsorption unit 12 is divided into multiple uniformly distributed adsorption pores 121. Each adsorption pore 121 is relatively independent and does not interfere with each other, which greatly improves the adsorption control capability of the adsorption disk 11 on the wafer and improves the control accuracy of wafer bonding during the wafer bonding process. At the same time, each heating unit 13 is also divided into multiple uniformly distributed heating blocks 131. Each adsorption pore 121 is relatively independent and does not interfere with each other, which also greatly improves the control capability of the adsorption disk 11 on the wafer heating temperature, improves the control accuracy of wafer temperature during the wafer bonding process, and is more conducive to preventing overheating in some areas.

[0034] In some alternative embodiments, refer to Figure 1 and Figure 3 As shown, the wafer bonding apparatus also includes an annular air pump 2, which is arranged around the outer periphery of the upper wafer adsorption stage 1, and each adsorption unit 12 is connected to the annular air pump 2. Furthermore, the upper wafer adsorption stage 1 is provided with a plurality of first air channels 14, which are arranged one-to-one with a plurality of adsorption units 12, and each adsorption unit 12 is connected to the annular air pump 2 through the corresponding first air channel 14.

[0035] Specifically, refer to Figure 1 and Figure 3 As shown, the annular air pump 2 is arranged around the outer periphery of the upper wafer adsorption stage 1. Optionally, a second air channel 15 is also provided in the upper wafer adsorption stage 1. The second air channel 15 is arranged in the horizontal direction and is connected to the annular air pump 2. Specifically, the annular air pump 2 extends from the center of the upper wafer adsorption stage 1. Each first air channel 14 is arranged in the vertical direction and connects the corresponding adsorption unit 12 and the second air channel 15, thereby realizing the connection between the adsorption unit 12 and the annular air pump 2.

[0036] In this embodiment of the invention, each adsorption unit 12 corresponds to a first air passage 14, which is beneficial to achieve independent airflow control for each adsorption unit 12.

[0037] Furthermore, in some optional embodiments, reference is made to... Figure 3As shown, each first air passage 14 is equipped with an air passage control valve 16, which is used to control the opening and closing of the corresponding first air passage 14. Specifically, each adsorption unit 12 corresponds to one air passage control valve 16, and the air passage control valve 16 is located at the upper end of each first air passage 14 corresponding to the adsorption unit 12. The air passage control valve 16 is specifically a remotely controllable electric valve. When the wafer is bonded from the center to the periphery, the air passage control valve 16 corresponding to the adsorption unit 12 closest to the center can be remotely controlled to close first, and then other air passage control valves 16 can be closed sequentially from the center to the periphery according to the bonding process.

[0038] In some alternative embodiments, refer to Figure 4 As shown, the wafer bonding equipment also includes a heating power supply 3 and multiple current switches 4. Each current switch 4 corresponds to one of the multiple heating units 3. The heating power supply 3 is electrically connected to each heating unit 13, and each current switch 4 controls the current flow between the heating power supply 3 and the corresponding heating unit 13. Specifically, the heating block 131 can be made of resistive materials such as resistance wire, and heat is generated by passing current through the heating block 131. When the wafer is bonded from the center to the periphery, the current switch 4 corresponding to the heating unit 13 closest to the center can be remotely turned off first, and then other current switches 4 can be sequentially turned off from the center to the periphery according to the bonding process, thereby achieving independent control of each heating unit 13.

[0039] In some alternative embodiments, refer to Figure 1 As shown, the wafer bonding apparatus also includes a bonding drive assembly 5 and a lower wafer support stage 6. The upper wafer adsorption stage 1 and the lower wafer support stage 6 are arranged vertically opposite each other. The output end of the bonding drive assembly 5 is connected to the upper surface of the upper wafer adsorption stage 1, and is used to drive the upper wafer adsorption stage 1 and the lower wafer support stage 6 to move closer to each other. Specifically, refer to... Figure 1 As shown, the bonding drive component 5 can be a linear motor.

[0040] In some alternative embodiments, refer to Figure 3 As shown, the wafer bonding apparatus also includes a push assembly 7, which is used to push the wafer center downwards. Specifically, refer to... Figure 1 As shown, the propulsion assembly 7 includes a thrust motor 71 and a propulsion rod 72. One end of the propulsion rod 72 is connected to the thrust motor 71, and the other end passes through the center of the upper wafer adsorption stage 1 from top to bottom. The bottom of the propulsion rod 72 is lower than the adsorption disk 11.

[0041] Specifically, refer to Figure 1 and Figure 2As shown, a through hole 111 is provided at the center of the upper wafer adsorption stage 1. A T-shaped push rod 72 passes through the through hole 111, and the lower end of the push rod 72 extends from the surface of the adsorption disk 11. When the upper wafer adsorption stage 1 adsorbs the upper wafer and moves directly above the lower wafer support stage 6, the push rod 72 is fed at a low speed under the push of the push motor 71, thereby pushing the center of the upper wafer to contact the lower wafer first. Due to the intermolecular forces and the push provided by the push rod 72, the two wafers are bonded together.

[0042] Furthermore, referring to Figure 3 As shown, the wafer bonding equipment also includes a force sensor 8, which is mounted on the push rod 72 and can be fixedly connected to the push rod 72 to detect the magnitude of the wafer bonding force in real time.

[0043] In some alternative embodiments, refer to Figure 1 As shown, the wafer bonding equipment also includes a mounting frame 9 for mounting the push assembly 7 and the bonding drive assembly 5. The mounting frame 9 is fixedly connected to the push motor 71 and the bonding drive assembly 5, respectively.

[0044] In some alternative embodiments, refer to Figure 4 As shown, the wafer bonding equipment may further include a control system 10, which is electrically connected to the pneumatic control valve 16, the current switch 4, the heating power supply 3, the thrust motor 71, and the force sensor 8. Specifically, the control system 10 is used to control the opening and closing of multiple pneumatic control valves 16 and the current switch 4, so that multiple adsorption units 12 and heating units 13 are closed sequentially from the center of the upper wafer adsorption stage 1 to the outer periphery; to adjust the heating temperature of the heating power supply 3; and to issue a control signal based on the bonding force information fed back by the force sensor 8 to adjust the thrust output of the thrust motor 71.

[0045] This invention integrates the adjustment functions of multiple physical quantities such as bonding force, heating temperature, and wafer adsorption through the control system 10, which can provide the ability to control multiple physical fields in a short bonding process, and improve the problems of low bonding power and slow response speed in current bonding equipment.

[0046] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A wafer bonding apparatus, characterized in that, The device includes an upper wafer adsorption stage (1), which includes an adsorption disk (11) located at the bottom. The adsorption disk (11) is provided with multiple adsorption units (12) and multiple heating units (13) that can work independently. The adsorption units (12) and the heating units (13) are respectively arranged in a ring shape. The multiple adsorption units (12) and the heating units (13) are arranged alternately from the center of the upper wafer adsorption stage (1) to the outer periphery. The wafer bonding equipment also includes a ring-shaped air pump (2), a heating power supply (3), multiple current switches (4), and a control system (10); the ring-shaped air pump (2) is arranged around the outer periphery of the upper wafer adsorption stage (1), and each adsorption unit (12) is connected to the ring-shaped air pump (2); multiple first air channels (14) are opened in the upper wafer adsorption stage (1), and the multiple first air channels (14) are arranged one-to-one with the multiple adsorption units (12), and each adsorption unit (12) is connected to the ring-shaped air pump (2) through the first air channel (14); each first air channel (14) is provided with an air channel control valve (16), and the air channel control valve (16) is used to control the opening and closing of the corresponding first air channel (14); Multiple current switches (4) are configured one-to-one with multiple heating units (13), the heating power supply (3) is electrically connected to each heating unit (13), and each current switch (4) is used to control the current flow between the heating power supply (3) and the corresponding heating unit (13). The control system (10) is electrically connected to the airway control valve (16) and the current switch (4), respectively. The control system (10) is used to control the opening and closing of multiple airway control valves (16) and the current switch (4) so ​​that multiple adsorption units (12) and heating units (13) are closed sequentially from the center of the upper wafer adsorption stage (1) to the outer periphery during the bonding process.

2. The wafer bonding equipment according to claim 1, characterized in that, Each of the adsorption units (12) includes a plurality of adsorption pores (121) spaced apart along the circumferential direction, and each of the heating units (13) includes a plurality of heating blocks (131) spaced apart along the circumferential direction.

3. The wafer bonding equipment according to claim 1, characterized in that, It also includes a bonding drive assembly (5) and a lower wafer support stage (6). The upper wafer adsorption stage (1) and the lower wafer support stage (6) are arranged opposite each other. The bonding drive assembly (5) is used to drive the upper wafer adsorption stage (1) and the lower wafer support stage (6) to move closer to each other.

4. The wafer bonding equipment according to claim 1, characterized in that, It also includes a propulsion component (7) for pushing the wafer center downward.

5. The wafer bonding equipment according to claim 4, characterized in that, The propulsion assembly (7) includes a thrust motor (71) and a propulsion rod (72). One end of the propulsion rod (72) is connected to the thrust motor (71), and the other end passes through the center of the upper wafer adsorption stage (1) from top to bottom.

6. The wafer bonding equipment according to claim 5, characterized in that, It also includes a force sensor (8), which is disposed on the push rod (72) for real-time detection of the magnitude of the wafer bonding force.

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