Wafer bonding methods, computer programs and their storage media

Abstract

This application provides a wafer bonding method, a computer program, and a storage medium thereof. The wafer bonding method includes: providing a first pair of wafers to be bonded; each wafer in the first pair of wafers to be bonded being adsorbed onto a first chuck and a second chuck; each wafer in the first pair of wafers to be bonded having a plurality of corresponding bonding alignment marks; the surface of the first chuck and / or the second chuck having a plurality of adsorption regions distributed circumferentially along the circle containing the chuck surface; according to the positional relationship between the plurality of bonding alignment marks of each wafer in the first pair of wafers to be bonded, controlling the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first pair of wafers to be bonded from the plurality of adsorption regions, to perform scaling compensation along multiple different directions on the first pair of wafers to be bonded; and bonding the first pair of wafers to be bonded after scaling compensation.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a wafer bonding method, a computer program, and a storage medium thereof. Background Technology

[0002] Wafer bonding is a process that integrates two or more chips with the same or different functions in three dimensions. Using wafer bonding can significantly reduce chip development and manufacturing cycles, shorten the metal interconnects between functional chips, and reduce heat generation, power consumption, and latency. Alignment accuracy is the most critical parameter in the bonding process.

[0003] However, in related technologies, there are problems such as poor compensation effect and low alignment accuracy during wafer bonding. Summary of the Invention

[0004] To address the related technical problems, embodiments of this application propose a wafer bonding method and apparatus, a computer program and its storage medium.

[0005] This application provides a wafer bonding method, including:

[0006] A first pair of wafers to be bonded is provided; each wafer in the first pair of wafers to be bonded is adsorbed on a first chuck and a second chuck respectively; each wafer in the first pair of wafers to be bonded has a corresponding plurality of bonding alignment marks; the surface of the first chuck and / or the second chuck has a plurality of adsorption areas distributed circumferentially along the circle on which the chuck surface is located;

[0007] Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first wafer pair to be bonded are controlled from the multiple adsorption regions respectively, so as to perform scaling compensation along multiple different directions on the first wafer pair to be bonded.

[0008] The first pair of wafers to be bonded, after scaling compensation, will be bonded.

[0009] In the above scheme, the number of the multiple adsorption regions is even, and two adsorption regions with the same diameter passing through the circle containing the chuck surface are jointly controlled.

[0010] In the above scheme, the area of ​​each of the multiple adsorption regions is equal.

[0011] In the above scheme, the first wafer pair to be bonded includes a first wafer adsorbed on the first chuck and a second wafer adsorbed on the second chuck, with the first chuck located above the second chuck;

[0012] The method further includes:

[0013] Scaling compensation is performed on the first wafer along multiple different directions, and scaling compensation is performed on the second wafer in one direction; or, scaling compensation is performed on the second wafer along multiple different directions, and scaling compensation is performed on the first wafer in one direction.

[0014] The method in the above scheme further includes:

[0015] Before controlling the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first wafer pair to be bonded from the plurality of adsorption regions, a downward force is applied to the first wafer.

[0016] The step of controlling the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafers in the first wafer pair to be bonded, based on the positional relationship between multiple bonding alignment marks on each wafer in the first wafer pair to be bonded, from the multiple adsorption regions, includes:

[0017] Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, the adsorption duration of the first chuck on the corresponding region of the first wafer is controlled from the multiple adsorption regions to perform scaling compensation on the first wafer along multiple different directions.

[0018] In the above scheme, the method further includes: while controlling the adsorption time of the first chuck on the first wafer from the plurality of adsorption regions respectively, adjusting the inflation pressure in the built-in cavity of the second chuck to perform scaling compensation in one direction on the second wafer.

[0019] The method in the above scheme further includes:

[0020] Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, a first set of coefficients is determined for scaling compensation of the first wafer along N different directions and a first set of coefficients for scaling compensation of the second wafer along one direction; the first set of coefficients includes N coefficients; where N is a positive integer greater than 1;

[0021] The duration for the first chuck to adsorb the first wafer is controlled along N different directions according to the first set of coefficients, and the inflation pressure in the built-in cavity of the second chuck is adjusted according to the first coefficients.

[0022] In the above scheme, the method further includes: when the second coefficient in the first coefficient set is greater than the third coefficient in the first coefficient set, controlling the adsorption time of the first chuck on the first wafer in the direction corresponding to the second coefficient to be greater than the adsorption time in the direction corresponding to the third coefficient.

[0023] The method in the above scheme further includes:

[0024] Analyze the bonding results of the first pair of wafers to be bonded;

[0025] When the bonding result does not meet the preset conditions, the first coefficient and the first coefficient set are adjusted, and the adjusted first coefficient and the first coefficient set are used to perform scaling compensation on the second wafer pair to be bonded.

[0026] The method in the above scheme further includes:

[0027] When performing scaling compensation along multiple different directions on the first wafer pair to be bonded, the relative positions between the wafers in the first wafer pair to be bonded are adjusted to perform translation compensation and / or rotation compensation on the first wafer pair to be bonded.

[0028] This application also provides a computer program that, when executed by a processor, causes the processor to perform the steps of the method described in this application.

[0029] This application embodiment also provides a computer program storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the method described in this application embodiment.

[0030] This application provides a wafer bonding method, a computer program, and a storage medium thereof. The wafer bonding method includes: providing a first pair of wafers to be bonded; each wafer in the first pair of wafers to be bonded being adsorbed onto a first chuck and a second chuck; each wafer in the first pair of wafers to be bonded having a plurality of corresponding bonding alignment marks; the surface of the first chuck and / or the second chuck having a plurality of adsorption regions distributed circumferentially along the circle on which the chuck surface is located; according to the positional relationship between the plurality of bonding alignment marks of each wafer in the first pair of wafers to be bonded, controlling the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first pair of wafers to be bonded from the plurality of adsorption regions, so as to perform scaling compensation along multiple different directions on the first pair of wafers to be bonded; and bonding the first pair of wafers to be bonded after scaling compensation. In the various embodiments of this application, the adsorption time and / or adsorption force of the chuck on the corresponding areas of the wafer are controlled in multiple different directions to achieve scaling compensation for the wafer pair to be bonded in multiple different directions. This enables scaling compensation for the wafer pair to be bonded from more directions, thereby better meeting the compensation requirements of multiple bonding alignment marks in different directions. As a result, the compensation effect is greatly improved, and the alignment accuracy in the bonding process is improved. Attached Figure Description

[0031] Figures 1a-1d This is a top view schematic diagram illustrating translational misalignment, rotational misalignment, scaling misalignment, and random error misalignment of the wafer to be bonded, provided in an embodiment of this application.

[0032] Figure 2 A top view schematic diagram of an misaligned wafer to be bonded, provided for an embodiment of this application;

[0033] Figure 3 A schematic diagram illustrating the implementation process of a wafer bonding method provided in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of a chuck with four adsorption areas provided in an embodiment of this application;

[0035] Figure 5 This is a schematic diagram illustrating scaling compensation in four directions during wafer bonding, as provided in an embodiment of this application.

[0036] Figures 6-11b This is a schematic diagram illustrating the implementation process of a wafer bonding method provided in an embodiment of this application. Detailed Implementation

[0037] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Each wafer in a wafer to be bonded has multiple corresponding bonding alignment marks. During wafer bonding, the bonding process mainly involves aligning the corresponding bonding alignment marks of the two wafers before proceeding with the bonding process. However, due to various reasons, when aligning two wafers to be bonded, at least some of the corresponding bonding alignment marks may exhibit alignment errors.

[0039] In some specific examples, the main alignment errors involved include translation (e.g. Figure 1a As shown), rotate (as shown) Figure 1b As shown), scaling (as shown) Figure 1c (as shown) and random errors (such as) Figure 1d (As shown). To correct these alignment errors, a basic alignment model abstracted from these errors has emerged. The basic alignment model is established based on the three major coordinate axis transformations. In some embodiments, the basic alignment model is calculated as shown in Equations 1 to 3 below. In some specific examples, the parts corresponding to the coordinate axis transformations, namely translation, rotation, and scaling, can be compensated by adjusting the process, while random errors cannot be compensated by adjusting the process.

[0040] dx i =Tx + S*X i -Rot*Y i +Random xi (1)

[0041] dy i =Ty + S*Y i +Rot*X i +Random yi (2)

[0042] Where i = 1, 2, ..., n represents the i-th bonding alignment mark; X represents the x-axis coordinate, Y represents the y-axis coordinate; dx represents the measurement value in the x-axis direction, dy represents the measurement value in the y-axis direction, Tx represents the translational alignment error compensation coefficient in the x-axis direction, Ty represents the translational alignment error compensation coefficient in the y-axis direction, S represents the scaling alignment error compensation coefficient, Rot represents the rotational alignment error compensation coefficient, and Random represents the random alignment error compensation coefficient.

[0043]

[0044] Where n represents the total number of bonding alignment marks; X represents the x-axis coordinate; Y represents the y-axis coordinate; dx represents the measurement value in the x-axis direction; dy represents the measurement value in the y-axis direction; Tx represents the translational alignment error compensation coefficient in the x-axis direction; Ty represents the translational alignment error compensation coefficient in the y-axis direction; S represents the scaling alignment error compensation coefficient; and Rot represents the rotational alignment error compensation coefficient.

[0045] It should be noted that translation is the offset of the relative position of the wafer pair in the radial direction of the wafer in a two-dimensional plane; rotation is the offset of the wafer pair in the two-dimensional plane with the wafer axis as the reference angle; scaling is the spatial offset in three-dimensional space when the wafers in the wafer pair undergo deformations such as expansion or contraction. In some specific examples, when performing compensation, equations 1 to 3 can be used for iterative calculation to obtain the compensation coefficient that minimizes the vector sum of all bonding alignment marks.

[0046] like Figure 1c As shown, in related technologies, scaling compensation is generally performed on the wafer as a whole in one direction. In the overall scaling alignment method of related technologies, the compensation coefficients can be expressed as translational alignment errors (translational alignment errors Tx along the first direction and Ty along the second direction), rotational alignment errors Rot, and scaling alignment errors S. That is, the alignment error compensation coefficients between wafers can be expressed as Tx, Ty, Rot, and S. Translational errors are generally compensated by adjusting the relative positions of the two wafers in wafer alignment along the radial direction of the wafer's circle. Rotational errors are generally compensated by adjusting the relative angles of the two wafers in wafer alignment along the axial direction of the wafer's circle. Scaling errors are generally compensated by adjusting the relative curvature of the two wafers in wafer alignment.

[0047] However, in some specific examples, due to the irregularity of wafer deformation, the vector value characterizing the alignment error of the bonding alignment marks on the wafer may exhibit the following characteristics: Figure 2 When the variation patterns of different regions are significantly different, it is difficult to cover all the bond alignment marks by using translation compensation, scaling compensation, or scaling compensation along one direction. The compensation effect is not good.

[0048] Based on this, in the various embodiments of this application, the chuck vacuum release time is controlled separately in multiple different directions to achieve scaling compensation for multiple different directions of the wafer pair to be bonded. This enables scaling compensation for the wafer pair to be bonded from more directions, thereby better meeting the compensation requirements of multiple bonding alignment marks in different directions. As a result, the compensation effect is greatly improved and the alignment accuracy in the bonding process is improved.

[0049] This application provides a wafer bonding method. Figure 3 This is a schematic diagram illustrating the implementation process of the wafer bonding method according to an embodiment of this application. Figure 3 As shown, the method includes the following steps:

[0050] Step 301: Provide a first pair of wafers to be bonded; each wafer in the first pair of wafers to be bonded is adsorbed on a first chuck and a second chuck respectively; each wafer in the first pair of wafers to be bonded has a corresponding plurality of bonding alignment marks; the surface of the first chuck and / or the second chuck has a plurality of adsorption areas distributed circumferentially along the circle on which the chuck surface is located;

[0051] Step 302: Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, control the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first wafer pair to be bonded from the multiple adsorption regions, so as to perform scaling compensation along multiple different directions on the first wafer pair to be bonded.

[0052] Step 303: Bond the first pair of wafers to be bonded after scaling compensation.

[0053] Here, the entity performing the wafer bonding method includes, but is not limited to, wafer bonding equipment.

[0054] In step 301, the first wafer pair to be bonded may include two wafers to be bonded, namely a first wafer and a second wafer; wherein the first wafer (also called the upper wafer) is adsorbed on the first chuck (also called the upper chuck), and the second wafer (also called the lower wafer) is adsorbed on the second chuck (also called the lower chuck).

[0055] In some specific examples, the wafer pair to be bonded may include two or more wafers with the same or different functions. For example, the wafer pair to be bonded may include a wafer with a complementary metal oxide semiconductor (CMOS) circuit and a wafer with a memory array structure.

[0056] Both the first and second wafers have multiple bonding alignment marks; and it is expected that the multiple bonding alignment marks of the first wafer and the multiple bonding alignment marks of the second wafer can be perfectly aligned during bonding of the first and second wafers to achieve accurate connection of the bonding contacts. However, in some specific examples, due to the influence of various processing techniques and other factors, there may be positional deviations between the multiple bonding alignment marks of the first wafer and the multiple bonding alignment marks of the second wafer, i.e., the aforementioned misalignments.

[0057] Here, the surfaces of the first chuck and the second chuck used to adsorb the wafer can be circular. The circular surfaces of the first chuck and / or the second chuck have multiple adsorption regions distributed circumferentially along the circle on which the chuck surface is located. In other words, the chuck is divided into multiple adsorption regions along its circumference.

[0058] Here, the adsorption region is used to adsorb the wafer. In some specific examples, the adsorption force of the adsorption region for fixing the wafer can be provided by the vacuum suction in a vacuum hole provided on the adsorption region. The vacuum hole can penetrate the wafer chuck and be located in the adsorption region of the wafer chuck. The vacuum hole provides vacuum suction by reducing the gas pressure in the vacuum hole through a vacuum control device, such as a pumping device.

[0059] In some embodiments, the number of the plurality of adsorption regions is even; two adsorption regions of the same diameter that pass through the circle containing the chuck surface are jointly controlled among the plurality of adsorption regions.

[0060] Here, two regions of the same diameter passing through the circle containing the chuck surface in the multiple adsorption regions correspond to one direction. In this embodiment, the adsorption region in one direction corresponds to one vacuum control device. That is to say, the adsorption regions in multiple directions can be controlled independently.

[0061] It should be noted that the adsorption areas on the first chuck and the second chuck can be the same or different. For example, the first chuck may have multiple adsorption areas distributed circumferentially along the circle containing the chuck surface; or, the second chuck may have multiple adsorption areas distributed circumferentially along the circle containing the chuck surface; or, both the first chuck and the second chuck may have multiple adsorption areas distributed circumferentially along the circle containing the chuck surface.

[0062] To facilitate coordinate conversion, in some embodiments, the areas of the multiple adsorption regions are equal. That is, adsorption regions corresponding to multiple different directions are evenly distributed along the circles containing the surfaces of the first and second chucks.

[0063] In some embodiments, the surface of the circular first chuck and / or second chuck has eight adsorption regions distributed along four directions.

[0064] In this embodiment, the shape of the adsorption region is not limited. In some embodiments, the shape of the adsorption region may include a fan shape. The fan-shaped adsorption region includes an arc-shaped region formed between a first distance and a second distance from the center of the circle containing the surface of the first chuck / second chuck; wherein the first distance is greater than the second distance.

[0065] In some specific examples, the first distance and the second distance can be adjusted according to the size of the wafer. For example, for a 12-inch wafer with a diameter of 300mm, the first distance can be 120mm and the second distance can be 100mm.

[0066] It should be noted that each adsorption region in the multiple adsorption regions is physically isolated, but two adsorption regions in the multiple adsorption regions that pass through the same diameter of the circle containing the chuck surface correspond to the same vacuum control device.

[0067] For example, such as Figure 4 As shown, the surface of the first chuck and / or the second chuck has eight adsorption regions along four directions: A-1, A-2, B-1, B-2, C-1, C-2, D-1, and D-2. Among them, the adsorption regions A-1 and A-2 are distributed along a 90° direction (denoted as S90); the adsorption regions B-1 and B-2 are distributed along a 45° direction (denoted as S45); the adsorption regions C-1 and C-2 are distributed along a 0° direction (denoted as S0); and the adsorption regions D-1 and D-2 are distributed along a 135° diameter direction (denoted as S135).

[0068] It should be noted that, Figure 4 This is an example only, used to explain the distribution and structural features of the adsorption regions in the embodiments of this application, and is not intended to limit the number or shape of the adsorption regions in the embodiments of this application.

[0069] In step 302, the main task is to perform scaling compensation along multiple different directions on the first pair of wafers to be bonded.

[0070] As previously mentioned, in some embodiments, the first wafer pair to be bonded includes a first wafer adsorbed on the first chuck and a second wafer adsorbed on the second chuck, with the first chuck (upper chuck) located above the second chuck (lower chuck). The first wafer is the upper wafer, and the second wafer is the lower wafer.

[0071] In some embodiments, the method further includes:

[0072] Scaling compensation is performed on the first wafer along multiple different directions, and scaling compensation is performed on the second wafer in one direction; or, scaling compensation is performed on the second wafer along multiple different directions, and scaling compensation is performed on the first wafer in one direction.

[0073] Here, when performing scaling compensation along multiple different directions on the first wafer pair to be bonded, the focus can be mainly on one wafer in the wafer pair, and then the remaining wafer can be compensated along one direction, or the whole wafer can be compensated. This can achieve compensation along different directions and simplify the compensation process.

[0074] In some embodiments, during the bonding process, a push pin can pass through the upper chuck and apply a downward force to the center of the circle containing the upper wafer. This force decreases across the entire wafer surface as the distance from the center increases. The upper chuck then adsorbs the wafer, providing an upward force. When the downward force applied by the push pin remains constant, the upward force applied to the wafer can be adjusted by changing the duration of wafer adsorption and / or the magnitude of the adsorption force (a longer adsorption duration means a longer time for the wafer to receive the push pin force in the adsorption area; a shorter adsorption duration means a shorter time for the wafer to receive the push pin force in the adsorption area). This corrects wafer deformation through the force applied to the wafer, thereby achieving scaling compensation and compensating for misalignment of the bonding marks caused by wafer deformation. When multiple adsorption regions exist, the adsorption time of each adsorption region can be controlled separately, allowing for scaling compensation along multiple directions. This better satisfies the compensation requirements of multiple bonding alignment marks in different directions, for example, effectively meeting the requirements of... Figure 2 The deformation correction requirement of the bonding alignment mark shown in the figure greatly improves the compensation effect and the alignment accuracy in the bonding process.

[0075] Understandably, considering the complexity of controlling the process when simultaneously performing multi-directional scaling compensation on both the upper and lower wafers, the lower wafer is used as the compensation reference standard, with multi-directional scaling compensation primarily applied to the upper wafer. It should be noted that the different compensation strategies for the upper and lower wafers can be interchanged, but the direction of the force applied by the ejector pins also needs to be adjusted accordingly when making this interchange.

[0076] In some embodiments, controlling the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafers in the first wafer pair to be bonded, respectively, from the plurality of adsorption regions based on the positional relationship between the plurality of bonding alignment marks of each wafer in the first wafer pair to be bonded, includes:

[0077] Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, the adsorption time of the first chuck on the first wafer is controlled from the multiple adsorption regions respectively.

[0078] In some embodiments, the method further includes: while controlling the adsorption duration of the first chuck on the first wafer from the plurality of adsorption regions, adjusting the inflation pressure in the built-in cavity of the second chuck to perform scaling compensation in one direction on the second wafer.

[0079] In other words, when performing scaling compensation, the deformation error between the upper and lower wafers can be compensated by adjusting the scaling compensation of a single wafer in different directions, such as the upper wafer; or completely different compensation strategies can be adopted for the upper and lower wafers, that is, the lower wafer is scaled and compensated as a whole in one direction, while the upper wafer is scaled and compensated separately in multiple different directions.

[0080] In some specific examples, considering that when performing scaling compensation, the process is more likely to perform amplification (expansion, or bending away from the chuck where the adsorption force is applied) compensation on the wafer, but less likely to perform shrinkage (bending towards the chuck where the adsorption force is applied) compensation on the wafer, scaling compensation can be performed on the wafer as a whole in one direction. This adjusts the magnitude of deformation errors such as expansion between the two wafers in one direction. For example, if the upper wafer needs to be compensated in a negative direction (shrinkage) relative to the lower wafer when the lower wafer is not compensated, positive direction (amplification) compensation can be performed on the lower wafer first, thereby pulling the compensation of the upper wafer relative to the lower wafer in a positive direction.

[0081] In some embodiments, when the wafer is scaled and compensated as a whole in one direction, the inflation pressure in the built-in cavity of the corresponding chuck can be adjusted so that the wafer follows the change in chord height of the protrusion on the chuck surface, thereby achieving wafer expansion and other deformation compensation.

[0082] In practical applications, the corresponding compensation coefficient can be determined based on the positional relationship between multiple bonding alignment marks on each wafer in the first wafer pair to be bonded, and then the adsorption time can be determined based on the compensation coefficient.

[0083] In some embodiments, the method further includes:

[0084] Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, a first set of coefficients is determined for scaling compensation of the first wafer along N different directions and a first set of coefficients for scaling compensation of the second wafer along one direction; the first set of coefficients includes N coefficients; where N is a positive integer greater than 1;

[0085] The duration for the first chuck to adsorb the first wafer is controlled along N different directions according to the first set of coefficients, and the inflation pressure in the built-in cavity of the second chuck is adjusted according to the first coefficients.

[0086] In some specific examples, the positional relationship between multiple bonding alignment marks on each wafer in the first wafer pair to be bonded can be measured using a bonding alignment mark measuring device. The alignment error of each bonding alignment mark on each wafer can be considered as a vector value. Specifically, the compensation coefficient can be determined by summing the vector values ​​corresponding to the alignment errors of all bonding alignment marks, iteratively calculating using the alignment model formula, and determining the compensation coefficient value when all vector values ​​are minimized.

[0087] Unlike the overall scaling alignment method in related technologies, the compensation coefficients of the scaling alignment method along N different directions in the embodiments of this application may include: translation misalignment compensation coefficients (displacement misalignment Tx along the first direction and displacement misalignment Ty along the second direction), rotation misalignment compensation coefficients Rot, and scaling misalignment coefficients in N directions. Taking N=4 as an example, that is, the N directions are 90° direction, 45° direction, 0° direction, and 135° direction. The scaling alignment error compensation coefficients corresponding to each direction are denoted as S90, S45, S0, and S135, respectively. In some specific embodiments, the misalignment compensation coefficients between wafers can be expressed as Tx, Ty, Rot, S0, S45, S90, and S135.

[0088] In some embodiments, when N=4, the alignment model is calculated as shown in Equations 4 to 5 below.

[0089] dx i =Tx+S0*X i +S45*(X i +Y i ) / 2+S135*(X i -Y i ) / 2-Rot*Y i +Random xi (4)

[0090] dy i =Ty+S45*(X i +Y i ) / 2+S90*Y i +S135*(X i -Y i ) / 2+Rot*X i +Random yi (5)

[0091] Where i = 1, 2, ..., n represents the i-th bonding alignment mark; X represents the x-axis coordinate, Y represents the y-axis coordinate; dx represents the measurement value in the x-axis direction, dy represents the measurement value in the y-axis direction, Tx represents the translational alignment error compensation coefficient in the x-axis direction, Ty represents the translational misalignment compensation coefficient in the y-axis direction, S0, S45, S90, and S135 represent the scaling alignment error compensation coefficients in different directions, Rot represents the rotational alignment error compensation coefficient, and Random represents the random alignment error compensation coefficient. In some specific examples, during compensation, equations 4 to 5 can be used for iterative calculation to obtain the compensation coefficient that minimizes the vector sum of the alignment errors representing all bonding alignment marks.

[0092] In some specific examples, the lower wafer can be scaled and compensated as a whole according to the first coefficient, while the upper wafer can be scaled and compensated separately along N different directions according to N coefficients in the first coefficient set.

[0093] In some embodiments, the method further includes: when a second coefficient in the first coefficient set is greater than a third coefficient in the first coefficient set, controlling the adsorption time of the first chuck on the first wafer in the direction corresponding to the second coefficient to be greater than the adsorption time in the direction corresponding to the third coefficient.

[0094] Here, the second and third coefficients are both coefficients from the first coefficient set. It should be noted that, in the embodiments of this application, the adsorption time for each region is determined by the magnitude of each coefficient in the first coefficient set, thereby adjusting the bonding alignment error. The sign of each coefficient in the first coefficient set can be controlled by its temporal relationship with the first coefficient.

[0095] The following specific example will further illustrate the implementation of scaling compensation along different directions in the embodiments of this application.

[0096] Combination Figures 5 to 11b Let's take N=4 as an example for further explanation. The alignment error compensation coefficients between wafers can be expressed as Tx, Ty, Rot, S0, S45, S90, S135. Using the aforementioned method for calculating the compensation coefficients, we obtain Tx = -0.03464um, Ty = -0.01346um, Rot = -0.02559, S0 = -0.25ppm, S90 = -0.42ppm, S45 = 0.09ppm, and S135 = 0.21ppm. Figure 5As shown. Here, the compensation coefficient is the compensation coefficient of the upper wafer, while the lower wafer serves as the reference standard for compensation. The compensation coefficient corresponding to the lower wafer can be 0, meaning that the lower wafer does not need to be compensated, and its position remains unchanged when no compensation is performed. Alternatively, the lower wafer can serve as the reference standard for compensation, and its corresponding compensation coefficient can be any value. In this case, the wafer uses this value as the distinguishing value between positive and negative coefficients. For the sign of each coefficient, the lower wafer is used as the reference standard. If S0 and S90 are both negative, the lower wafer can be compensated as a whole, making the directions of S0 and S90 relative to the compensated lower wafer positive. Since S45 and S135 are both positive, the positive amplitude of S45 and S135 relative to the compensated lower wafer will increase. Then, the adsorption time of the first chuck on the first wafer in the directions corresponding to S45 and S135 is controlled based on this increased amplitude. For example, if the compensation coefficient corresponding to the lower wafer is set to 0.5ppm, then S0 = -0.25ppm, S90 = -0.42ppm, S45 = 0.09ppm, and S135 = 0.21ppm will all become: S0' = 0.25ppm, S90' = 0.08ppm, S45' = 0.59ppm, and S135' = 0.71ppm. At this point, the scaling alignment error coefficients of the upper wafer in each direction all become positive, meaning that expansion forces or bending towards the chuck direction away from the direction of the adsorption force can be applied in all four directions. Furthermore, S135' = 0.71ppm is the largest scaling alignment error coefficient, corresponding to the direction requiring the greatest degree of scaling compensation and the longest time required for the ejector pin to act, i.e., the longest adsorption time.

[0097] The scaling compensation for each wafer in the first wafer pair to be bonded is implemented as follows in this example:

[0098] like Figure 6 Both wafers are mounted on their respective chucks, ready for scaling compensation operations.

[0099] Next, as Figure 7 A force is applied to the center of the first wafer (upper wafer) using a push pin. At this time, the cavity of the second wafer (lower wafer) is inflated, causing the chord height of the cavity to reach a preset value. This causes the second wafer to deform along with the cavity, achieving scaling compensation. Here, the preset value is determined based on the corresponding compensation coefficient of the lower wafer, such as the aforementioned 0.5 ppm.

[0100] Next, as Figure 8a , 8b In the S90 direction, the adsorption effect of the adsorption region on the first wafer is turned off. At this time, the adsorption effect on the first wafer is maintained in the S0, S45, and S135 directions, while maintaining the gas pressure in the inner cavity of the second wafer.

[0101] Next, as Figure 9a , 9b In the S0 direction, the adsorption effect of the adsorption region on the first wafer is turned off, while the adsorption effect on the first wafer is maintained in the S45 and S135 directions, while maintaining the gas pressure in the inner cavity of the second wafer.

[0102] Next, as Figure 10a , 10b In the S45 direction, the adsorption effect of the adsorption region on the first wafer is turned off, while in the S135 direction, the adsorption effect on the first wafer is maintained, and the gas pressure in the cavity of the second wafer is maintained.

[0103] Next, as Figure 11a , 11b In the direction of S135, the adsorption effect of the adsorption region on the first wafer is turned off. At this time, the adsorption effect of all adsorption regions on the first wafer has been released, and the gas pressure in the inner cavity of the second wafer can be turned off. At this point, the scaling compensation is completed.

[0104] It should be noted that, Figure 8b for Figure 8a Cross-sectional view along the CC direction; Figure 9b for Figure 9a Cross-sectional view along the AA direction; Figure 10b for Figure 10a Cross-sectional view along the BB direction; Figure 11b for Figure 11a Cross-sectional view along the DD direction. Figure 7 , Figure 8b , Figure 9b , Figure 10b The degree of wafer deformation shown is only to highlight the scaling compensation process and does not represent the actual deformation of the wafer during the compensation process.

[0105] In some embodiments, the method further includes:

[0106] When performing scaling compensation along multiple different directions on the first wafer pair to be bonded, the relative positions between the wafers in the first wafer pair to be bonded are adjusted to perform translation compensation and / or rotation compensation on the first wafer pair to be bonded.

[0107] Here, in the example, Tx = -0.03464µm and Ty = -0.01346µm are the compensation coefficients for translation compensation, and Rot = -0.02559 is the compensation coefficient for rotation compensation. Based on the translation compensation coefficients, the relative positions of the two wafers in wafer alignment along the radial direction of the wafer circle are adjusted to achieve compensation. Based on the rotation error, the relative angles of the two wafers in wafer alignment along the axial direction of the wafer circle are adjusted to achieve compensation.

[0108] In some embodiments, the method further includes:

[0109] Analyze the bonding results of the first pair of wafers to be bonded;

[0110] When the bonding result does not meet the preset conditions, the first coefficient and the first coefficient set are adjusted, and the adjusted first coefficient and the first coefficient set are used to perform scaling compensation on the second wafer pair to be bonded.

[0111] In some specific examples, after the previous wafer pair to be bonded is completed, the first coefficient and the first coefficient set can be corrected based on the bonding result, and the corrected first coefficient and the first coefficient set can be used to perform scaling compensation on the next wafer pair to be bonded. It is understood that multiple trials can be used to determine the optimal first coefficient and the first coefficient set for use in mass production.

[0112] In step 303, the wafers in the first wafer pair to be bonded can be bonded by any bonding method, such as adhesive bonding, anodic bonding, direct wafer bonding, metal bonding, or hybrid bonding.

[0113] In some embodiments, when the wafer pair to be bonded is a wafer with a CMOS circuit and a wafer with a memory array structure, the wafers in the wafer pair to be bonded can be bonded as a hybrid bonding (also known as "metal / dielectric hybrid bonding").

[0114] The wafer bonding method provided in this application embodiment involves providing a first pair of wafers to be bonded; each wafer in the first pair of wafers to be bonded is adsorbed onto a first chuck and a second chuck; each wafer in the first pair of wafers to be bonded has a corresponding plurality of bonding alignment marks; the surface of the first chuck and / or the second chuck has a plurality of adsorption regions distributed circumferentially along the circle on which the chuck surface is located; according to the positional relationship between the plurality of bonding alignment marks of each wafer in the first pair of wafers to be bonded, the adsorption duration and / or adsorption force of the first chuck and / or the second chuck on the corresponding wafer in the first pair of wafers to be bonded are controlled from the plurality of adsorption regions to perform scaling compensation along multiple different directions on the first pair of wafers to be bonded; and the first pair of wafers to be bonded after scaling compensation is bonded. In the various embodiments of this application, the adsorption time and / or adsorption force of the chuck on the corresponding areas of the wafer are controlled in multiple different directions to achieve scaling compensation for the wafer pairs to be bonded in multiple different directions. This enables scaling compensation for the wafer pairs to be bonded from more directions, thereby better meeting the compensation requirements of multiple bonding alignment marks in different directions. As a result, the compensation effect is greatly improved, and the alignment accuracy in the bonding process is enhanced.

[0115] This application also provides a computer program that, when executed by a processor, causes the processor to perform the steps of the bonding method described in this application.

[0116] This application also provides a storage medium storing a computer program that, when executed by at least one processor, implements the bonding method provided in this application.

[0117] In some embodiments, the storage medium may be a magnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM), etc.; or it may be a device that includes one or any combination of the above-mentioned memories.

[0118] In some embodiments, a computer program may take the form of a program, software, software module, script, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0119] As an example, a computer program may, but does not necessarily, correspond to a file in a file system. It may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a Hyper Text Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple collaborating files (e.g., a file that stores one or more modules, subroutines, or code sections).

[0120] As an example, a computer program may be deployed to execute on a single computing device, or on multiple computing devices located in one location, or on multiple computing devices distributed across multiple locations and interconnected via a communication network.

[0121] The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method or device embodiments.

[0122] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer bonding method, characterized in that, include: Provide the first pair of wafers to be bonded; Each wafer in the first pair of wafers to be bonded is adsorbed onto a first chuck and a second chuck, respectively; each wafer in the first pair of wafers to be bonded has a plurality of corresponding bonding alignment marks; the surface of the first chuck and / or the second chuck has a plurality of adsorption regions distributed circumferentially along the circle on which the chuck surface is located; the number of the plurality of adsorption regions is even; two adsorption regions that are radially opposite each other in the plurality of adsorption regions are jointly controlled; and two regions in the plurality of adsorption regions that pass through the same diameter of the circle on which the chuck surface is located correspond to one direction; the adsorption regions in the plurality of directions are controlled independently. Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, compensation coefficients are determined along multiple different directions; the directions pass through two opposing adsorption regions in the radial direction of the circle on which the chuck surface is located; Based on the compensation coefficients along the multiple different directions, the adsorption time of the first chuck and / or the second chuck on the corresponding wafer in the first wafer pair to be bonded is controlled from the multiple adsorption regions respectively, so as to perform scaling compensation along the multiple different directions on the first wafer pair to be bonded. The first pair of wafers to be bonded after the scaling compensation is performed is then bonded. Before controlling the adsorption time of the first chuck and / or the second chuck on the corresponding wafer in the first wafer pair to be bonded from the plurality of adsorption regions, a downward force is applied to the first wafer of the first wafer pair to be bonded.

2. The method according to claim 1, characterized in that, Each of the multiple adsorption regions has an equal area.

3. The method according to claim 2, characterized in that, The first wafer pair to be bonded includes a first wafer adsorbed on the first chuck and a second wafer adsorbed on the second chuck, wherein the first chuck is located above the second chuck; The method further includes: Scaling compensation is performed on the first wafer along multiple different directions, and scaling compensation is performed on the second wafer in one direction; or, scaling compensation is performed on the second wafer along multiple different directions, and scaling compensation is performed on the first wafer in one direction.

4. The method according to claim 3, characterized in that, The method further includes: The step of controlling the adsorption time of the first chuck and / or the second chuck for the corresponding wafer in the first wafer pair to be bonded, based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, from the multiple adsorption regions, includes: Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, the adsorption duration of the first chuck on the first wafer is controlled from the multiple adsorption regions to perform scaling compensation on the first wafer along multiple different directions.

5. The method according to claim 4, characterized in that, The method further includes: while controlling the adsorption time of the first chuck on the first wafer from the plurality of adsorption regions respectively, adjusting the inflation pressure in the built-in cavity of the second chuck to perform scaling compensation in one direction on the second wafer.

6. The method according to claim 5, characterized in that, The method further includes: Based on the positional relationship between multiple bonding alignment marks of each wafer in the first wafer pair to be bonded, a first set of coefficients is determined for scaling compensation of the first wafer along N different directions and a first set of coefficients for scaling compensation of the second wafer along one direction; the first set of coefficients includes N coefficients; where N is a positive integer greater than 1; The duration for the first chuck to adsorb the first wafer is controlled along N different directions according to the first set of coefficients, and the inflation pressure in the built-in cavity of the second chuck is adjusted according to the first coefficients.

7. The method according to claim 6, characterized in that, The method further includes: When the second coefficient in the first coefficient set is greater than the third coefficient in the first coefficient set, the adsorption time of the first chuck on the first wafer in the direction corresponding to the second coefficient is controlled to be greater than the adsorption time in the direction corresponding to the third coefficient.

8. The method according to claim 6, characterized in that, The method further includes: Analyze the bonding results of the first pair of wafers to be bonded; When the bonding result does not meet the preset conditions, the first coefficient and the first coefficient set are adjusted, and the adjusted first coefficient and the first coefficient set are used to perform scaling compensation on the second wafer pair to be bonded.

9. The method according to claim 1, characterized in that, The method further includes: When performing scaling compensation along multiple different directions on the first wafer pair to be bonded, the relative positions between the wafers in the first wafer pair to be bonded are adjusted to perform translation compensation and / or rotation compensation on the first wafer pair to be bonded.

10. A computer program, characterized in that, When the computer program is executed by a processor, the processor performs the steps of the method according to any one of claims 1 to 9.

11. A computer program storage medium, characterized in that, The computer program storage medium stores a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1 to 9.

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