Wafer bonding method
By correcting the wafer bonding and position adjustment, and calculating the motion error of the bonding machine, the alignment deviation problem caused by the motion error of the bonding machine was solved, and high-precision wafer bonding was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI INTEGRATED CIRCUIT EQUIPMENT & MATERIALS INDUSTRY INNOVATION CENTER CO LTD
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-05
Smart Images
Figure CN122161397A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit manufacturing, and in particular to a wafer bonding method. Background Technology
[0002] Fusion bonding is one of the wafer bonding processes. Ideally, the alignment marks on the upper wafer are perfectly aligned with those on the lower wafer. However, in actual wafer bonding processes, there are motion errors in the bonding machine, resulting in alignment deviations between the upper and lower wafers, which in turn increases the alignment offset between them. However, in current fusion bonding processes, because the upper and lower wafers are designed with only two alignment marks, it is impossible to accurately fit the wafer alignment offset using these marks, thus failing to compensate for the motion errors of the bonding machine. Summary of the Invention
[0003] The purpose of this invention is to provide a wafer bonding method to compensate for the motion error of the bonding machine and improve the alignment accuracy of the product wafer.
[0004] To achieve the above objectives, the present invention provides a wafer bonding method, comprising:
[0005] Provide a first calibration wafer and a second calibration wafer to be bonded;
[0006] The first calibration wafer and the second calibration wafer are bonded together using a bonding machine.
[0007] Obtain the coordinates of multiple location points on the first and second calibration wafers;
[0008] The motion error of the bonding machine is obtained based on the coordinates of multiple location points.
[0009] Provide a first product wafer and a second product wafer to be bonded;
[0010] The positions of the first product wafer and the second product wafer are adjusted according to the motion error, and the first product wafer and the second product wafer are bonded by the bonding machine.
[0011] Optionally, the method for obtaining the motion error of the bonding machine includes:
[0012] The alignment offset between the first calibration wafer and the second calibration wafer is obtained based on the coordinates of the multiple location points;
[0013] Obtain the APC system compensation amount between the first correction wafer and the second correction wafer during the bonding process;
[0014] The difference between the alignment offset and the APC system compensation is obtained to obtain the motion error compensation of the bonding machine.
[0015] The motion error of the bonding machine is calculated based on the motion error compensation amount.
[0016] Optionally, the first calibration wafer has a plurality of first alignment marks, and the second calibration wafer has a plurality of second alignment marks, wherein the plurality of first alignment marks on the bonded first calibration wafer correspond one-to-one with the plurality of second alignment marks on the second calibration wafer.
[0017] Optionally, by obtaining the coordinates of multiple first alignment marks and multiple second alignment marks, the coordinates of multiple position points of the first and second calibration wafers can be obtained.
[0018] Optionally, the method for obtaining the alignment offset between the first calibration wafer and the second calibration wafer based on the coordinates of the plurality of said location points includes:
[0019] Based on the coordinates of the first alignment mark and the second alignment mark at the multiple location points, the positional deviations of multiple location points between the first calibration wafer and the second calibration wafer are obtained;
[0020] The positional deviations of the multiple said position points are fitted to obtain the alignment offset between the first correction wafer and the second correction wafer.
[0021] Optionally, the alignment offset includes translation offset, rotation offset, and runout offset between the first calibration wafer and the second calibration wafer.
[0022] Optionally, the APC system compensation amount includes deformation compensation amount and runout compensation amount.
[0023] Optionally, the motion error includes the transmission error of the bonding machine and the bonding error.
[0024] Optionally, before bonding the first product wafer and the second product wafer using the bonding machine, the wafer bonding method further includes:
[0025] The first calibration wafer and the second calibration wafer are bonded at predetermined intervals, and the coordinates of multiple position points of the first calibration wafer and the second calibration wafer are obtained. The motion error of the bonding machine is obtained based on the coordinates of the multiple position points.
[0026] Optionally, the method for adjusting the positions of the first product wafer and the second product wafer based on the amount of motion error includes:
[0027] The first product wafer is translated and / or rotated according to the amount of motion error, or the second product wafer is translated and / or rotated according to the amount of motion error.
[0028] In the wafer bonding method provided by this invention, a first calibration wafer and a second calibration wafer are first bonded together using a bonding machine. Then, the coordinates of multiple position points on the first and second calibration wafers are obtained. Next, the motion error of the bonding machine is obtained based on the coordinates of the multiple position points. Then, the positions of the first and second product wafers are adjusted according to the motion error, and the first and second product wafers are bonded together using the bonding machine. That is, adjusting the positions of the first and second product wafers according to the motion error compensates for the motion error of the bonding machine. By compensating for the motion error of the bonding machine, the alignment accuracy between the first and second product wafers is improved, thereby improving the bonding accuracy between the first and second product wafers. Attached Figure Description
[0029] Figure 1 This is a schematic flowchart of the wafer bonding method provided in an embodiment of the present invention;
[0030] Figure 2 This is a top view of the first calibration wafer in the wafer bonding method provided in this embodiment of the invention;
[0031] Figure 3 This is a top view of the second calibration wafer in the wafer bonding method provided in this embodiment of the invention;
[0032] Figure 4 This is a schematic diagram of the structure after the first correction wafer and the second correction wafer are bonded in the wafer bonding method provided in this embodiment of the invention;
[0033] Figure 5 This is a schematic diagram illustrating the principle of positional offset between the first alignment mark and the second alignment mark in the wafer bonding method provided in this embodiment of the invention.
[0034] Figure 6 This is a schematic diagram of the structure of the first product wafer and the second product wafer after bonding in the wafer bonding method provided in this embodiment of the invention;
[0035] The reference numerals in the attached figures are explained as follows:
[0036] 100 - First calibration wafer; 101 - First alignment mark; 200 - Second calibration wafer; 201 - Second alignment mark; 300 - First product wafer; 400 - Second product wafer. Detailed Implementation
[0037] The wafer bonding method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.
[0038] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature.
[0039] Figure 1 This is a schematic flowchart of the wafer bonding method provided in an embodiment of the present invention. Figure 1 As shown, the wafer bonding method provided in this embodiment includes:
[0040] Step S1: Provide a first calibration wafer and a second calibration wafer to be bonded;
[0041] Step S2: Bond the first calibration wafer and the second calibration wafer using a bonding machine;
[0042] Step S3: Obtain the coordinates of multiple location points of the first calibration wafer and the second calibration wafer;
[0043] Step S4: Obtain the motion error of the bonding machine based on the coordinates of the multiple position points;
[0044] Step S5: Provide the first product wafer and the second product wafer to be bonded;
[0045] Step S6: Adjust the positions of the first product wafer and the second product wafer according to the motion error amount, and bond the first product wafer and the second product wafer using the bonding machine.
[0046] Figure 2This is a top view of the first calibration wafer in the wafer bonding method provided in this embodiment of the invention; Figure 3 This is a top view of the second calibration wafer in the wafer bonding method provided in this embodiment of the invention; Figure 4 This is a schematic diagram of the structure after the first correction wafer and the second correction wafer are bonded in the wafer bonding method provided in this embodiment of the invention; Figure 5 This is a schematic diagram illustrating the principle of positional offset between the first alignment mark and the second alignment mark in the wafer bonding method provided in this embodiment of the invention. Figure 6 This is a schematic diagram of the structure after bonding the first product wafer and the second product wafer in the wafer bonding method provided in this embodiment of the invention. The following will refer to the attached diagram. Figures 2 to 6 The wafer bonding method provided in this embodiment will be described in more detail.
[0047] First, execute step S1, as follows: Figure 2 and Figure 3 As shown, a first calibration wafer 100 and a second calibration wafer 200 to be bonded are provided. The first calibration wafer 100 can be a device wafer, and the second calibration wafer 200 can be a carrier wafer; or, the first calibration wafer 100 is a carrier wafer, and the second calibration wafer 200 is a device wafer. The device wafer can be a pixel wafer containing a pixel array of an image sensor, or a MEMS wafer containing a MEMS microstructure of MEMS devices, or a MOSFET wafer or IGBT wafer containing power devices, or a passive device wafer, etc., the type of device wafer depending on the function of the final device to be fabricated. The carrier wafer may not contain a functional structure; or, the carrier wafer may contain a functional structure.
[0048] The first calibration wafer 100 and the second calibration wafer 200 are disposed opposite to each other, that is, the first calibration wafer 100 is located above or below the second calibration wafer 200, the side of the first calibration wafer 100 close to the second calibration wafer 200 can be the front or back of the first calibration wafer 100, and the side of the second calibration wafer 200 close to the first calibration wafer 100 can be the front or back of the second calibration wafer 200.
[0049] Next, proceed to step S2, as follows: Figure 4 As shown, the first calibration wafer 100 and the second calibration wafer 200 are bonded using a bonding machine.
[0050] In this embodiment, the bonding machine includes a robotic arm, a first chuck, and a second chuck. The robotic arm is used to transfer a first calibration wafer 100 and a second calibration wafer 200, so as to transfer the first calibration wafer 100 from its initial position to the first chuck and to transfer the second calibration wafer 200 to the second chuck.
[0051] The first chuck and the second chuck are arranged opposite to each other. The first chuck is used to carry the first calibration wafer 100, and the second chuck is used to carry the second calibration wafer 200. During the bonding process, the position alignment between the first calibration wafer 100 and the second calibration wafer 200 is achieved by moving the first chuck or the second chuck.
[0052] In this embodiment, the first calibration wafer 100 and the second calibration wafer 200 can be bonded using a hybrid bonding process, that is, by bonding the metal layers on the surfaces of the first calibration wafer 100 and the second calibration wafer 200. In this way, higher alignment accuracy can be achieved.
[0053] Specifically, such as Figure 2 As shown, the first calibration wafer 100 has a plurality of first alignment marks 101. For example... Figure 3 As shown, the second calibration wafer 200 has a plurality of second alignment marks 201, and the number of first alignment marks 101 on the first calibration wafer 100 and the number of second alignment marks 201 on the second calibration wafer 200 are the same. Specifically, the number of both the first alignment marks 101 and the second alignment marks 201 is greater than or equal to twelve. If the number of the first alignment marks 101 and the second alignment marks 201 is small, for example less than twelve, then the alignment offset cannot be subsequently fitted using the first alignment marks 101 and the second alignment marks 201. Therefore, in this embodiment, the number of both the first alignment marks 101 and the second alignment marks 201 is greater than or equal to twelve.
[0054] In this embodiment, during the bonding process between the first calibration wafer 100 and the second calibration wafer 200, alignment and bonding are performed using the coordinates of multiple first alignment marks 101 and multiple second alignment marks 201. After bonding, the multiple first alignment marks 101 on the first calibration wafer 100 correspond one-to-one with the multiple second alignment marks 201 on the second calibration wafer 200.
[0055] Next, step S3 is executed to obtain the coordinates of multiple position points of the first alignment wafer 100 and the second alignment wafer 200. Specifically, by obtaining the coordinates of multiple first alignment marks 101 and multiple second alignment marks 201, the coordinates of multiple position points of the first alignment wafer 100 and the second alignment wafer 200 are obtained, that is, the coordinates of multiple first alignment marks 101 and the coordinates of multiple second alignment marks 201 corresponding to the first alignment marks 101 are obtained.
[0056] Furthermore, the coordinates of the first alignment mark 101 and the second alignment mark 201 both include coordinates in a first direction and coordinates in a second direction. The first direction and the second direction are perpendicular to each other. The first direction can be the X direction and the second direction can be the Y direction.
[0057] Next, step S4 is executed to obtain the motion error of the bonding machine based on the coordinates of the multiple position points.
[0058] Specifically, the method for obtaining the motion error of the bonding machine includes: firstly, obtaining the alignment offset between the first calibration wafer and the second calibration wafer 200 based on the coordinates of multiple position points. Specifically, the positional deviations of multiple position points between the first calibration wafer 100 and the second calibration wafer 200 can be obtained firstly based on the coordinates of multiple first alignment marks 101 and multiple second alignment marks 201. That is, the positional deviations between the first alignment mark 101 and its corresponding second alignment mark 201 can be calculated based on the coordinates of multiple first alignment marks 101 and multiple second alignment marks 201, thereby obtaining the positional deviations of multiple position points between the first calibration wafer 100 and the second calibration wafer 200.
[0059] like Figure 5 As shown, Figure 5 A point in the diagram represents a location point A, and an arrow corresponding to location point A represents the positional deviation between the first alignment mark 101 and the second alignment mark 201 of location point A. Figure 5 The different directions of the arrows indicate that the positional offset directions between the first alignment mark 101 and the second alignment mark 201 are different, and the distance between position point A and the arrow indicates the magnitude of the positional deviation between the first alignment mark 101 and the second alignment mark 201.
[0060] Then, the positional deviations of multiple location points A are fitted to obtain the alignment accuracy between the first calibration wafer 100 and the second calibration wafer 200. The alignment accuracy includes translational offset, rotational offset, and runout offset between the first calibration wafer 100 and the second calibration wafer 200.
[0061] Furthermore, the alignment offset is caused by the motion error of the bonding machine during the bonding process of the first and second calibration wafers and the compensation amount of the APC (Advanced Process Control) system, i.e., the alignment offset = motion error + APC system compensation. The motion error includes the transfer error of the bonding machine and the bonding error. The transfer error refers to the error during the transfer of the first calibration wafer 100 and the second calibration wafer 200, such as the transfer error when the robotic arm transfers the first calibration wafer 100 to the first chuck, and the transfer error when the robotic arm transfers the second calibration wafer 200 to the second chuck. The bonding error refers to the error caused by the variation in the precision of the bonding machine during the bonding process of the first and second calibration wafers 100 and 200.
[0062] It should be noted that the APC system compensation amount refers to the compensation amount calculated by the APC system during the bonding process of the first correction wafer 100 and the second correction wafer 200, and used to adjust the positions of the first correction wafer 100 and the second correction wafer 200. The APC system compensation amount includes the deformation compensation amount and the runout compensation amount between the first correction wafer 100 and the second correction wafer 200.
[0063] Next, the APC system compensation amount is obtained during the bonding process of the first correction wafer 100 and the second correction wafer 200; wherein, the APC system compensation amount can be obtained through the records in the APC system.
[0064] Next, the difference between the alignment offset and the APC system compensation is obtained to determine the motion error compensation of the bonding machine. Then, the motion error of the bonding machine is calculated based on the motion error compensation.
[0065] In a further embodiment, the first calibration wafer 100 and the second calibration wafer 200 are bonded at predetermined time intervals. The coordinates of multiple positions on the bonded first calibration wafer 100 and the second calibration wafer 200 are obtained, and the motion error of the bonding machine is obtained based on these coordinates. This yields the motion error of the bonding machine in its current state, improving the accuracy of compensating for the motion error of the bonding machine during subsequent product wafer bonding processes. The predetermined time interval can be, for example, one week.
[0066] Next, proceed to step S5, as follows: Figure 6As shown, a first product wafer 300 and a second product wafer 400 to be bonded are provided. Specifically, the first product wafer 300 can be a device wafer, and the second product wafer 400 can be a carrier wafer; or, the first product wafer 300 is a carrier wafer, and the second product wafer 400 is a device wafer. The carrier wafer may not contain a functional structure; or, the carrier wafer may contain a functional structure. The device wafer can be a pixel wafer containing a pixel array of an image sensor, or a MEMS wafer containing a MEMS microstructure of MEMS devices, or a MOSFET wafer or IGBT wafer containing power devices, or a passive device wafer, etc. The type of device wafer depends on the function of the final device to be fabricated.
[0067] The first product wafer 300 and the second product wafer 400 are disposed opposite to each other, that is, the first product wafer 300 is located above or below the second product wafer 400. The side of the first product wafer 300 closest to the second product wafer 400 can be either the front or the back of the first product wafer 300, and the side of the second product wafer 400 closest to the first product wafer 300 can be either the front or the back of the second product wafer 400. Both the first product wafer 300 and the second product wafer 400 are provided with two alignment marks.
[0068] Next, proceed to step S6, as follows: Figure 6 As shown, the positions of the first product wafer 300 and the second product wafer 400 are adjusted according to the amount of motion error, and the bonding machine is used to bond the first product wafer 300 and the second product wafer 400. That is, adjusting the positions of the first product wafer 300 and the second product wafer 400 according to the amount of motion error compensates for the motion error of the bonding machine. By compensating for the motion error of the bonding machine, the alignment accuracy between the first product wafer 300 and the second product wafer 400 is improved, thereby improving the bonding accuracy between the first product wafer 300 and the second product wafer 400.
[0069] For example, the first product wafer 300 is translated and / or rotated according to the motion error amount, or the second product wafer 400 is translated and / or rotated according to the motion error amount, to adjust the positions of the first product wafer 300 and the second product wafer 400. Specifically, the motion error compensation amount of the bonding machine can be calculated first based on the motion error amount, and the positions of the first product wafer 300 and the second product wafer 400 can be adjusted according to the motion error compensation amount, thereby compensating for the motion error of the bonding machine.
[0070] In this embodiment, the first product wafer 300 and the second product wafer 400 can be bonded by fusion bonding, that is, by bonding through the dielectric layer on the surface of the first product wafer 300 and the second product wafer 400. Compared with the hybrid bonding process, the process of bonding the first product wafer 300 and the second product wafer 400 by fusion bonding can simplify the process flow.
[0071] Furthermore, after bonding the first product wafer and the second product wafer using the wafer bonding method provided in this embodiment, the alignment accuracy (or alignment offset) between the first product wafer and the second product wafer can be improved to less than 500 nm, as measured.
[0072] In summary, in the wafer bonding method provided in this embodiment of the invention, a first calibration wafer and a second calibration wafer are first bonded together using a bonding machine; then, the coordinates of multiple position points on the first and second calibration wafers are obtained; next, the motion error of the bonding machine is obtained based on the coordinates of the multiple position points; then, the positions of the first and second product wafers are adjusted based on the motion error, and the first and second product wafers are bonded together using the bonding machine. This compensates for the motion error of the bonding machine, thereby improving the alignment accuracy between the first and second product wafers, and consequently improving the bonding accuracy between the first and second product wafers.
[0073] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.
[0074] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.
Claims
1. A wafer bonding method, characterized in that, include: Provide a first calibration wafer and a second calibration wafer to be bonded; The first calibration wafer and the second calibration wafer are bonded together using a bonding machine. Obtain the coordinates of multiple location points on the first and second calibration wafers; The motion error of the bonding machine is obtained based on the coordinates of multiple location points. Provide a first product wafer and a second product wafer to be bonded; The positions of the first product wafer and the second product wafer are adjusted according to the motion error, and the first product wafer and the second product wafer are bonded by the bonding machine.
2. The wafer bonding method as described in claim 1, characterized in that, The method for obtaining the motion error of the bonding machine includes: The alignment offset between the first calibration wafer and the second calibration wafer is obtained based on the coordinates of the multiple location points; Obtain the APC system compensation amount between the first correction wafer and the second correction wafer during the bonding process; The difference between the alignment offset and the APC system compensation is obtained to obtain the motion error compensation of the bonding machine. The motion error of the bonding machine is calculated based on the motion error compensation amount.
3. The wafer bonding method as described in claim 2, characterized in that, The first calibration wafer has a plurality of first alignment marks, and the second calibration wafer has a plurality of second alignment marks. The plurality of first alignment marks on the first calibration wafer after bonding correspond one-to-one with the plurality of second alignment marks on the second calibration wafer.
4. The wafer bonding method as described in claim 3, characterized in that, By acquiring the coordinates of multiple first alignment marks and multiple second alignment marks, the coordinates of multiple position points of the first and second calibration wafers are obtained.
5. The wafer bonding method as described in claim 4, characterized in that, The method for obtaining the alignment offset between the first calibration wafer and the second calibration wafer based on the coordinates of multiple said location points includes: Based on the coordinates of the first alignment mark and the second alignment mark at the multiple location points, the positional deviations of multiple location points between the first calibration wafer and the second calibration wafer are obtained; The positional deviations of the multiple said position points are fitted to obtain the alignment offset between the first correction wafer and the second correction wafer.
6. The wafer bonding method as described in claim 2, characterized in that, The alignment offset includes translation offset, rotation offset, and runout offset between the first calibration wafer and the second calibration wafer.
7. The wafer bonding method as described in claim 2, characterized in that, The compensation amount of the APC system includes deformation compensation amount and runout compensation amount.
8. The wafer bonding method as described in claim 1, characterized in that, The motion error includes the transmission error and bonding error of the bonding machine.
9. The wafer bonding method as described in claim 1, characterized in that, Before bonding the first product wafer and the second product wafer using the bonding machine, the wafer bonding method further includes: The first calibration wafer and the second calibration wafer are bonded at predetermined intervals, and the coordinates of multiple position points of the first calibration wafer and the second calibration wafer are obtained. The motion error of the bonding machine is obtained based on the coordinates of the multiple position points.
10. The wafer bonding method as described in claim 1, characterized in that, The method for adjusting the positions of the first product wafer and the second product wafer based on the motion error includes: The first product wafer is translated and / or rotated according to the amount of motion error, or the second product wafer is translated and / or rotated according to the amount of motion error.