Wafer bonding alignment mechanism and wafer bonding method

Abstract

The invention provides a wafer bonding alignment mechanism and a wafer bonding method, and relates to the technical field of semiconductor manufacturing. The wafer bonding alignment mechanism comprises a chuck used for bearing a wafer, and the wafer is provided with a first mark; the chip mounting head is used for adsorbing and fixing a chip, and the chip is provided with a second mark; the chip mounting head adsorbs one side of the chip and faces the wafer; and the imaging system is positioned on one side, far away from the chip mounting head, of the chuck, and is used for emitting an imaging light beam, receiving the detection light beam reflected by the first mark and the second mark, and imaging according to the detection light beam. The embodiment of the invention provides a wafer bonding alignment mechanism and a wafer bonding method. Positioning errors caused by mechanical movement, vibration and movement control are avoided. Errors caused by coordinate system conversion are avoided, continuous repeated alignment can be achieved, and the high-precision positioning requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a wafer bonding alignment mechanism and a wafer bonding method. Background Art

[0002] With the development of integrated circuit technology, the approach of following Moore's Law to improve performance by reducing the size of transistors is increasingly encountering bottlenecks. This challenge has prompted a technological shift from traditional silicon-based single homogeneous integration processes to heterogeneous integration, and from planar integration to three-dimensional integration. Hybrid bonding is a key technical means to achieve three-dimensional heterogeneous integration. Unlike traditional bump welding technology, hybrid bonding is to bond two smooth dielectric surfaces together through processes such as heating and annealing to form an electrical connection. Wafer-level operations are extremely demanding on bonding equipment, requiring alignment accuracy of hundreds of nanometers or even tens of nanometers.

[0003] During the bonding alignment process, the mainstream bonding method is to use two sets of upper and lower cameras to respectively identify and align the alignment marks on the chip and the target wafer, and use the upper visual camera to take pictures to locate the chip position; use the lower visual camera to take pictures to locate the wafer position, and then use a certain functional relationship to transform the coordinate system to achieve the alignment of the chip mark and the wafer mark, thereby achieving high-precision bonding; however, this positioning method of the upper and lower alignment system is difficult to avoid positioning errors caused by mechanical movement, equipment vibration and motion control, and cannot meet the high-precision positioning requirements of wafer bonding.

[0004] Patent CN202211429519.2 discloses a wafer bonding device and method. By setting an observation through hole on the wafer chuck, it is determined whether the positioning mark is aligned in the observation through hole. The wafer mark and the chip mark use the same set of cameras. Although high-precision alignment is achieved, this method has certain disadvantages:

[0005] (1) Future advanced packaging requires that the same wafer be compatible with chips of different sizes, and the same equipment be compatible with wafers of different functions. Opening an observation hole through the chuck is only applicable to Wafer to Wafer hybrid bonding process, and is not applicable to future advanced packaging processes such as Chip to Wafer hybrid bonding process or TCB (thermal compression bonding).

[0006] (2) Once a different product is changed, the corresponding chuck needs to be replaced, which is not conducive to dust-free FAB operation. After the chuck is replaced, the bonding equipment needs to be re-debugged, which greatly wastes efficiency and cannot achieve automated die bonding for multiple products. Summary of the invention

[0007] The embodiment of the present invention provides a wafer bonding alignment mechanism and a wafer bonding method, which avoids positioning errors caused by mechanical movement, vibration and motion control, avoids errors caused by coordinate system conversion, can continuously repeat alignment, and meets high-precision positioning requirements.

[0008] In a first aspect, an embodiment of the present invention provides a wafer bonding alignment mechanism, comprising:

[0009] A chuck, used for carrying a wafer, wherein the wafer is provided with a first mark;

[0010] A chip mounting head is used for adsorbing and fixing a chip, wherein the chip is provided with a second mark; the chip mounting head adsorbs one side of the chip toward the wafer;

[0011] The imaging system is located on a side of the chuck away from the patch head, and is used to emit an imaging beam, receive a detection beam reflected by the first mark and the second mark, and form an image based on the detection beam.

[0012] Optionally, the imaging system includes a detection light source and an imaging device;

[0013] The detection light source is used to emit the imaging light beam, and the imaging device is used to receive the detection light beam and form an image according to the detection light beam;

[0014] The detection light source and the imaging device are integrated into one.

[0015] Optionally, the imaging device includes a camera and a lens, and the detection light source is fixed on the lens;

[0016] In a direction perpendicular to the chuck, the lens is located between the chuck and the camera.

[0017] Optionally, the imaging device includes a camera and a lens, and the detection light source is fixed on the lens;

[0018] The wafer bonding alignment mechanism also includes a reflection mechanism. Along a direction parallel to the chuck, the lens is located between the camera and the reflection mechanism. The reflection mechanism is used to reflect the imaging beam to the chuck and reflect the detection beam to the lens.

[0019] Optionally, the detection light source is located on a side of the lens away from the camera;

[0020] Alternatively, the detection light source is located on a side of the lens.

[0021] Optionally, the imaging light beam includes visible light and invisible light;

[0022] The invisible light includes at least one of infrared light and ultraviolet light.

[0023] Optionally, the chuck includes a base and a light-transmitting body, the thickness of the base is greater than the thickness of the light-transmitting body, and the base and the light-transmitting body form a groove.

[0024] In a second aspect, an embodiment of the present invention provides a wafer bonding method based on the wafer bonding alignment mechanism of the first aspect, comprising:

[0025] Controlling the imaging system to emit an imaging beam, the imaging beam penetrates the chuck and is projected onto the wafer carried by the chuck, the first mark on the wafer is reflected to form a first detection beam, and the position of the first mark is identified according to the first detection beam received by the imaging system;

[0026] Controlling a chip placement head that adsorbs and fixes the chip to move to the top of the wafer, and after preliminary positioning, controlling an imaging system to emit an imaging beam, the imaging beam penetrates the chuck and the wafer and projects onto the chip, the second mark on the chip reflects to form a second detection beam, and the position of the second mark is identified according to the second detection beam received by the imaging system;

[0027] The chip and / or the wafer are moved according to the position of the first mark and the position of the second mark to align the chip with the wafer.

[0028] Optionally, identifying the position of the first mark according to the first detection light beam received by the imaging system comprises:

[0029] Based on the first detection beams received by at least two imaging systems, the positions of the first marks at at least two locations are simultaneously identified.

[0030] Optionally, the chuck comprises a base and a light-transmitting body, the thickness of the base is greater than the thickness of the light-transmitting body, and the base and the light-transmitting body form a groove;

[0031] Controlling the imaging system to emit an imaging beam, wherein the imaging beam penetrates the chuck and projects onto the wafer carried by the chuck, including:

[0032] The imaging system is controlled to emit an imaging light beam, and the imaging light beam penetrates the light-transmitting body and the groove in the chuck and is projected onto the wafer carried by the chuck.

[0033] In the wafer bonding alignment mechanism provided by the embodiment of the present invention, the first mark of the wafer, the second mark of the chip, the characteristic edge or other positioning features and the placement head share a set of visual positioning systems to avoid positioning errors caused by mechanical movement, vibration and motion control. In the process of bonding, errors caused by coordinate system conversion are avoided, and alignment can be repeated continuously to meet high-precision positioning requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0037] Figure 4 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0038] Figure 5 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0039] Figure 6 for Figure 5 Schematic diagram of the chuck and wafer;

[0040] Figure 7 A schematic diagram of another chuck and wafer provided in an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention;

[0042] Fig. 9 A flowchart of a wafer bonding method is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0044] Figure 1 A schematic diagram of a wafer bonding alignment mechanism provided by an embodiment of the present invention, referring to Figure 1 The wafer bonding alignment mechanism includes a chuck 11, a patch head 21 and an imaging system 30. The chuck 11 is used to carry a wafer 12, and the wafer 12 is provided with a first mark 13. Figure 1 A first mark 13 is shown schematically, which is not a limitation of the embodiment of the present invention. The wafer 12 may be provided with one or more first marks 13. The first mark 13 may be located on the surface of the wafer 12 facing the chuck 11, or the first mark 13 may be located on the surface of the wafer 12 away from the chuck 11. The mounting head 21 is used to adsorb and fix the chip 22, and the chip 22 is provided with a second mark 23. Figure 1A second mark 23 is shown in the figure, which is not a limitation of the embodiment of the present invention. The chip 22 may be provided with one or more second marks 23. The second mark 23 may be located on the surface of the chip 22 facing the patch head 21, or the second mark 23 may be located on the surface of the chip 22 away from the patch head 21.

[0045] The bonding head 21 adsorbs one side of the chip 22 toward the wafer 12. Therefore, when the bonding head 21 moves above the wafer 12, the chip 22 moves with the bonding head 21, and the chip 22 is also located above the wafer 12. The imaging system 30 is located on the side of the chuck 11 away from the bonding head 21. The imaging system 30 is used to emit an imaging beam, receive a detection beam reflected by the first mark 13 and the second mark 23, and form an image based on the detection beam. Then, the positions of the first mark 13 and the second mark 23 can be determined based on the image formed by the imaging system 30, so that the wafer 12 and the chip 22 can be aligned through the first mark 13 and the second mark 23, and bonded together.

[0046] In the wafer bonding alignment mechanism provided by the embodiment of the present invention, the first mark 13 of the wafer 12, the second mark 23 of the chip 22, the characteristic edge or other positioning features and the placement head 21 share a set of visual positioning systems to avoid positioning errors caused by mechanical movement, vibration and motion control. In the process of bonding, errors caused by coordinate system conversion are avoided, and alignment can be repeated continuously to meet high-precision positioning requirements.

[0047] Figure 2 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention, referring to Figure 2 The imaging system 30 includes a detection light source 31 and an imaging device 32. The detection light source 31 is used to emit an imaging light beam, and the imaging device 32 is used to receive the detection light beam and form an image according to the detection light beam. The detection light source 31 and the imaging device 32 are integrated into one. The detection light source 31 is fixed on the imaging device 32. In other embodiments, the detection light source 31 and the imaging device 32 can also be separately arranged, and the detection light source 31 and the imaging device 32 are arranged at a certain distance in space.

[0048] Optionally, refer to Figure 2 The imaging device 32 includes a camera 33 and a lens 34, and the detection light source 31 is fixed on the lens 34. In the direction perpendicular to the chuck 11, the lens 34 is located between the chuck 11 and the camera 33. In the wafer bonding alignment mechanism, the imaging device 32 is installed vertically. The imaging light beam emitted by the detection light source 31 is vertically projected onto the chuck 11 and the wafer 12. The light reflected by the first mark 13 on the wafer 12 passes through the chuck 11 and then passes through the lens 34, and is finally imaged by the camera 33.

[0049] Figure 3A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention, referring to Figure 3 The imaging device 32 includes a camera 33 and a lens 34, and the detection light source 31 is fixed on the lens 34. The wafer bonding alignment mechanism also includes a reflection mechanism 40. In a direction parallel to the chuck 11, the lens 34 is located between the camera 33 and the reflection mechanism 40. The reflection mechanism 40 is used to reflect the imaging beam to the chuck 11, and reflect the detection beam to the lens 34.

[0050] For example, reference Figure 3 The imaging light beam emitted by the detection light source 31 is projected to the reflection mechanism 40 along the horizontal direction, and after being reflected by the reflection mechanism 40 , it propagates along the vertical direction and is vertically projected to the chuck 11 and the wafer 12 .

[0051] For example, reference Figure 3 The reflection mechanism 40 includes a prism or a reflector.

[0052] Optionally, refer to Figure 2 and Figure 3 , the detection light source 31 is located on the side of the lens 34 away from the camera 33. The lens 34 is located between the detection light source 31 and the camera 33.

[0053] Figure 4 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention, referring to Figure 4 , the detection light source 31 is located on the side of the lens 34. The detection light source 31 will not block the detection light beam entering the lens 34, thereby improving the detection accuracy.

[0054] Optionally, the imaging light beam includes visible light and invisible light. The invisible light includes at least one of infrared light and ultraviolet light.

[0055] Figure 5 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention, Figure 6 for Figure 5 Schematic diagram of the chuck and wafer, see Figure 5 and Figure 6 The chuck 11 includes a base 14 and a light-transmitting body 15. The thickness of the base 14 is greater than that of the light-transmitting body 15. The base 14 and the light-transmitting body 15 form a groove 16. In the embodiment of the present invention, the groove 16 is provided on the chuck 11, and the imaging beam and the detection beam can pass through the chuck 11 via the position of the groove 16. That is, the imaging beam and the detection beam pass through the light-transmitting body 15 at a position with a thinner thickness, rather than passing through the base 14 at a position with a thicker thickness, thereby increasing the transmittance of the imaging beam and the detection beam and improving the detection accuracy.

[0056] For example, reference Figure 5 and Figure 6, along a direction perpendicular to the chuck 11 , the light-transmitting body 15 is located between the groove 16 and the wafer 12 .

[0057] Figure 7 A schematic diagram of another chuck and wafer provided in an embodiment of the present invention, referring to Figure 7 , along a direction perpendicular to the chuck 11 , the groove 16 is located between the light-transmitting body 15 and the wafer 12 .

[0058] For example, reference Figure 5-Figure 7 , the first mark 13 is directly opposite to the groove 16. The orthographic projection of the first mark 13 on the chuck 11 is located in the groove 16, so that the imaging beam is projected to the first mark 13, and the detection beam reflected by the first mark 13 passes through the groove 16.

[0059] Figure 8 A schematic diagram of another wafer bonding alignment mechanism provided by an embodiment of the present invention, referring to Figure 8 The wafer bonding alignment mechanism includes at least two imaging systems 30. Therefore, when the chip 22 is relatively large, at least two imaging systems 30 may be used to simultaneously observe the first marks 13 at different positions on the wafer 12.

[0060] Fig. 9 A flowchart of a wafer bonding method is provided for an embodiment of the present invention, referring to Figure 1-Figure 4 ,as well as Fig. 9 , wafer bonding methods include:

[0061] S101, controlling an imaging system to emit an imaging beam, the imaging beam penetrates the chuck and is projected onto a wafer carried by the chuck, a first mark on the wafer is reflected to form a first detection beam, and a position of the first mark is identified based on the first detection beam received by the imaging system.

[0062] S102, control the placement head that adsorbs and fixes the chip to move to the top of the wafer. After preliminary positioning, control the imaging system to emit an imaging beam. The imaging beam penetrates the chuck and the wafer and is projected onto the chip. The second mark on the chip is reflected to form a second detection beam. The position of the second mark is identified based on the second detection beam received by the imaging system.

[0063] S103 , moving the chip and / or the wafer according to the position of the first mark and the position of the second mark to align the chip with the wafer.

[0064] Exemplarily, according to the position of the first mark 13 and the position of the second mark 23, at least one of the chip 22 and the wafer 12 is moved, and through multiple fine-tuning, the second mark 23 of the chip 22 and the first mark 13 of the wafer 12 are made to coincide with each other, thereby meeting the high-precision alignment requirements.

[0065] The wafer bonding method provided in the embodiment of the present invention is based on the wafer bonding alignment mechanism in the above embodiment to identify the position of the first mark 13 of the wafer 12, identify the position of the second mark 23 of the chip 22, and fine-tune the alignment according to the position of the first mark 13 and the position of the second mark 23. The first mark 13 of the wafer 12, the second mark 23 of the chip 22, the feature edge or other positioning features share a set of visual positioning systems with the placement head 21. During the die bonding process, errors caused by coordinate system conversion are avoided, and alignment can be repeated continuously to meet high-precision positioning requirements.

[0066] Optionally, refer to Figure 8 and Fig. 9 The step of identifying the position of the first mark according to the first detection beam received by the imaging system includes: simultaneously identifying the position of the first mark at at least two positions according to the first detection beams received by at least two imaging systems.

[0067] For example, reference Figure 8 The imaging system 30 in the wafer bonding alignment mechanism includes a first imaging system 301 and a second imaging system 302. The first imaging system 301 and the second imaging system 302 are arranged at a certain distance. The first mark 13 in the wafer 12 includes a first sub-mark 131 and a second sub-mark 132. The first sub-mark 131 and the second sub-mark 132 are arranged at a certain distance. In the step of identifying the first mark 13, for example, the first imaging system 301 can be used to identify the first sub-mark 131, and the second imaging system 302 can be used to identify the second sub-mark 132 to improve the efficiency of identification.

[0068] Optionally, refer to Figure 5-Figure 7 ,as well as Fig. 9 The chuck 11 includes a base 14 and a light-transmitting body 15, the thickness of the base 14 is greater than the thickness of the light-transmitting body 15, and the base 14 and the light-transmitting body 15 form a groove 16. The step of controlling the imaging system to emit an imaging beam, and the imaging beam penetrates the chuck and projects to the wafer carried by the chuck, includes: controlling the imaging system to emit an imaging beam, and the imaging beam penetrates the light-transmitting body and the groove in the chuck and projects to the wafer carried by the chuck. The imaging beam and the detection beam are controlled to pass through the light-transmitting body 15 at a thinner thickness position, rather than passing through the base 14 at a thicker thickness position, thereby increasing the transmittance of the imaging beam and the detection beam and improving the detection accuracy.

[0069] Exemplarily, before step S101 , the wafer bonding method may further include: aligning the first mark 13 with the groove 16 on the chuck 11 . That is, the projection of the first mark 13 in a direction perpendicular to the chuck 11 is located in the groove 16 .

[0070] For example, in step S102, controlling the chip placement head for adsorbing and fixing the chip to move above the wafer may include: controlling the chip placement head for adsorbing and fixing the chip to move above the wafer, and controlling the second mark 23 to align with the groove 16 on the chuck 11. That is, the projection of the second mark 23 in a direction perpendicular to the chuck 11 is located in the groove 16.

[0071] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A wafer bonding alignment mechanism, characterized in that: include: A chuck, used for carrying a wafer, wherein the wafer is provided with a first mark; A chip mounting head is used for adsorbing and fixing a chip, wherein the chip is provided with a second mark; the chip mounting head adsorbs one side of the chip toward the wafer; The imaging system is located on a side of the chuck away from the patch head, and is used to emit an imaging beam, receive a detection beam reflected by the first mark and the second mark, and form an image based on the detection beam.

2. The wafer bonding alignment mechanism according to claim 1, characterized in that: The imaging system comprises a detection light source and an imaging device; The detection light source is used to emit the imaging light beam, and the imaging device is used to receive the detection light beam and form an image according to the detection light beam; The detection light source and the imaging device are integrated into one.

3. The wafer bonding alignment mechanism according to claim 2, characterized in that: The imaging device comprises a camera and a lens, and the detection light source is fixed on the lens; In a direction perpendicular to the chuck, the lens is located between the chuck and the camera.

4. The wafer bonding alignment mechanism according to claim 2, characterized in that: The imaging device comprises a camera and a lens, and the detection light source is fixed on the lens; The wafer bonding alignment mechanism also includes a reflection mechanism. Along a direction parallel to the chuck, the lens is located between the camera and the reflection mechanism. The reflection mechanism is used to reflect the imaging beam to the chuck and reflect the detection beam to the lens.

5. The wafer bonding alignment mechanism according to claim 3 or 4, characterized in that: The detection light source is located at a side of the lens away from the camera; Alternatively, the detection light source is located on a side of the lens.

6. The wafer bonding alignment mechanism according to claim 1, characterized in that: The imaging light beam includes visible light and invisible light; The invisible light includes at least one of infrared light and ultraviolet light.

7. The wafer bonding alignment mechanism according to claim 1, characterized in that: The chuck includes a base body and a light-transmitting body, the base body has a thickness greater than that of the light-transmitting body, and the base body and the light-transmitting body form a groove.

8. A wafer bonding method based on the wafer bonding alignment mechanism according to claim 1, characterized in that: include: Controlling the imaging system to emit an imaging beam, the imaging beam penetrates the chuck and is projected onto the wafer carried by the chuck, the first mark on the wafer is reflected to form a first detection beam, and the position of the first mark is identified according to the first detection beam received by the imaging system; Controlling a chip placement head that adsorbs and fixes the chip to move to the top of the wafer, and after preliminary positioning, controlling an imaging system to emit an imaging beam, the imaging beam penetrates the chuck and the wafer and projects onto the chip, the second mark on the chip reflects to form a second detection beam, and the position of the second mark is identified according to the second detection beam received by the imaging system; The chip and / or the wafer are moved according to the position of the first mark and the position of the second mark to align the chip with the wafer.

9. The wafer bonding method according to claim 8, characterized in that: Identifying a position of the first mark according to the first detection beam received by the imaging system comprises: Based on the first detection beams received by at least two imaging systems, the positions of the first marks at at least two locations are simultaneously identified.

10. The wafer bonding method according to claim 8, characterized in that: The chuck comprises a base and a light-transmitting body, the base has a thickness greater than that of the light-transmitting body, and the base and the light-transmitting body form a groove; Controlling the imaging system to emit an imaging beam, wherein the imaging beam penetrates the chuck and projects onto the wafer carried by the chuck, including: The imaging system is controlled to emit an imaging light beam, and the imaging light beam penetrates the light-transmitting body and the groove in the chuck and is projected onto the wafer carried by the chuck.

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