Wafer measurement apparatus, method, and wafer bonding apparatus

Abstract

The application relates to the field of integrated circuits, and discloses a wafer measuring device, a wafer measuring method and a wafer bonding device. The wafer measuring device comprises an air pressure measuring module and a data processing module. The air pressure measuring module comprises a measuring air path, a reference air path, a reference plane and a differential pressure gauge. A measuring throttle valve is arranged on the measuring air path, and a measuring nozzle is arranged at the end of the measuring air path. A reference throttle valve is arranged on the reference air path, and a reference nozzle is arranged at the end of the reference air path. The beginning of the measuring air path and the beginning of the reference air path are connected to an air source. The first end of the differential pressure gauge is connected to the front section of the measuring air path between the measuring throttle valve and the measuring nozzle; and the second end of the differential pressure gauge is connected to the front section of the reference air path between the reference throttle valve and the reference nozzle.

Description

Technical Field

[0001] This application relates to the field of integrated circuits, and specifically to a wafer measurement device, method, and wafer bonding equipment. Background Technology

[0002] In the integrated circuit manufacturing process, to create microelectromechanical systems (MEMS) or achieve chip packaging, two pre-fabricated wafers are directly bonded together, a process known as W2W (Wafer to Wafer) bonding. This bonding process involves aligning the two wafers face-to-face before bonding them together, followed by annealing to solidify the contact surfaces and achieve complete bonding between the two wafers.

[0003] However, during the bonding process, the relative parallelism between the two wafers directly affects the subsequent bonding result, thus impacting product yield and final performance. Poor relative parallelism between the two wafers can lead to incomplete bonding or reduced bond strength. It can also cause defects such as particles, fragments, and scratches at the wafer edges or bonding interface. Therefore, determining the relative parallelism between the two wafers is crucial in W2W bonding.

[0004] In existing W2W bonding technology, before bonding, the wafer is sent to a dedicated metrology device to test its flatness, thereby preventing wafer flatness defects from affecting relative parallelism during the bonding process. Common methods for testing flatness include contact probe methods or optical interferometry. Contact probe methods use mechanical probes to directly contact the wafer surface, which may damage patterned devices on the wafer surface and generate particulate contamination, making them unsuitable for high-precision bonding processes. While optical interferometry does not directly contact the wafer, the reflectivity of the wafer surface is not 100%, and there are stacked layers of different materials inside. This means that the "surface" detected by the light is not the wafer surface itself, but rather below the surface, with a deviation of ±0.05 to 0.15 μm, and this deviation range varies depending on the wafer product. Furthermore, after metrology, the wafer may undergo deposition, cleaning, and activation processes before bonding, which may change its flatness. Therefore, existing methods for determining relative parallelism have many shortcomings and need improvement. Summary of the Invention

[0005] In view of this, embodiments of this application provide a wafer measurement apparatus, method, and wafer bonding equipment that can avoid damage to the wafer surface or cause particulate contamination, and improve measurement accuracy.

[0006] The technical solution of this application embodiment is implemented as follows:

[0007] This application provides a wafer measurement device applied to a wafer bonding equipment. The wafer measurement device includes a pneumatic measurement module and a data processing module. The pneumatic measurement module includes a measurement gas path, a reference gas path, a reference plane, and a differential pressure gauge. A measurement throttle valve is provided on the measurement gas path, and a measurement nozzle is provided at the end of the measurement gas path. A reference throttle valve is provided on the reference gas path, and a reference nozzle is provided at the end of the reference gas path. The beginnings of the measurement gas path and the reference gas path are both connected to a gas source. The first end of the differential pressure gauge is connected to the measurement throttle valve. The measurement gas path is connected to the valve and the measuring nozzle; the second end of the differential pressure gauge is connected to the reference gas path between the reference throttle valve and the reference nozzle; the measuring nozzle is used to spray gas onto the surface of the wafer to be bonded; the reference nozzle is used to spray gas onto the reference plane; the differential pressure gauge is used to measure the pressure difference between the measurement gas path and the reference gas path when gas is sprayed from the measuring nozzle and the reference nozzle; the data processing module is used to determine the relative parallelism between the two wafers to be bonded based on the pressure difference.

[0008] In some embodiments of this application, the wafer measuring device further includes: a mechanical shaft; the measuring nozzle, the reference nozzle, and the reference plane are all disposed at the end of the mechanical shaft; the mechanical shaft moves mechanically to move the measuring nozzle in a region close to the surface of the wafer to be bonded.

[0009] In some embodiments of this application, the number of measuring gas paths is two; the measuring nozzles of the two measuring gas paths are arranged opposite to each other at the ends of the mechanical shaft and respectively facing the two wafers to be bonded; the first end of the differential pressure gauge branches out into two sub-ends, and a switching valve is provided at the branch position; the two sub-ends of the differential pressure gauge are respectively connected to the front section of the measuring gas path of the two measuring gas paths.

[0010] In some embodiments of this application, the number of the measuring gas path is one; the mechanical shaft moves mechanically to orient the measuring nozzle of the measuring gas path toward any one of the wafers to be bonded.

[0011] In some embodiments of this application, the measuring gas path and the reference gas path are both connected to a gas source via a main gas path; a flow controller and a gas processor are provided on the main gas path; the flow controller is used to control the flow rate of the gas in the main gas path; the gas processor is used to filter and clean the gas in the main gas path.

[0012] In some embodiments of this application, the wafer measurement device further includes: an adjustment module; the adjustment module is used to control the stage of the wafer bonding equipment to perform a compensation action when the relative parallelism exceeds a threshold, until the relative parallelism meets the threshold requirement.

[0013] In some embodiments of this application, the adjustment module includes at least three piezoelectric actuators; the at least three piezoelectric actuators are disposed at the edge of the stage and drive the stage to perform the compensation action.

[0014] In some embodiments of this application, during the gas ejection process of the measuring nozzle, the distance between the measuring nozzle and the surface of the wafer to be bonded is less than 150 μm; the diameters of both the measuring nozzle and the reference nozzle are less than 500 mm and greater than 0.5 mm.

[0015] This application embodiment also provides a wafer measurement method, which includes: moving a measurement nozzle to a region close to the surface of the wafer to be bonded; opening a measurement throttle valve to allow the measurement nozzle to spray gas onto the surface of the wafer to be bonded, and opening a reference throttle valve to allow a reference nozzle to spray gas onto a reference plane; wherein the opening degree of the measurement throttle valve and the opening degree of the reference throttle valve are consistent with corresponding preset calibration opening degrees; measuring the pressure difference between the front section of the measurement gas path and the front section of the reference gas path using a differential pressure gauge; wherein the front section of the measurement gas path is located between the measurement throttle valve and the measurement nozzle; the front section of the reference gas path is located between the reference throttle valve and the reference nozzle; and determining the relative parallelism between the two wafers to be bonded based on the pressure difference.

[0016] In some embodiments of this application, after determining the relative parallelism between the two wafers to be bonded, the wafer measurement method further includes: if the relative parallelism exceeds a threshold, controlling the stage of the wafer bonding equipment to perform a compensation action until the relative parallelism meets the threshold requirement.

[0017] In some embodiments of this application, the measurement nozzle is used to spray gas onto the surface of the wafer to be bonded, which includes: translating the measurement nozzle to spray gas onto a plurality of measurement points on the surface of the wafer to be bonded; wherein the plurality of measurement points are distributed in a linear or grid pattern on the wafer to be bonded.

[0018] In some embodiments of this application, determining the relative parallelism between two wafers to be bonded based on the pressure difference includes: determining global gap data for each of the two wafers to be bonded based on the pressure difference; wherein the global gap data includes the gaps corresponding to multiple test points on the surface of the wafers to be bonded; the gap is the distance between the measuring nozzle and the surface of the wafers to be bonded; performing differential calculation on the global gap data of the two wafers to be bonded to obtain global relative gap difference data between the two wafers to be bonded; performing plane fitting on the global relative gap difference data to obtain a minimum mean square error plane; wherein the tilt of the minimum mean square error plane characterizes the relative parallelism between the two wafers to be bonded.

[0019] In some embodiments of this application, after obtaining the global gap data of each of the two wafers to be bonded, the wafer measurement method further includes: performing plane fitting on the global gap data of the two wafers to be bonded respectively to obtain a fitting plane of the surfaces of the two wafers to be bonded; wherein the shape of the fitting plane characterizes the flatness of the surface of the wafers to be bonded.

[0020] In some embodiments of this application, after obtaining the minimum mean square error plane, the wafer measurement method further includes: simulating and adjusting the minimum mean square error plane to obtain a target horizontal plane; determining the geometric operation of adjusting the minimum mean square error plane to the target horizontal plane; and controlling the stage of the wafer bonding equipment to perform compensation actions based on the geometric operation.

[0021] This application also provides a wafer bonding apparatus, which includes the wafer measurement device described in the above-described scheme.

[0022] It is understandable that by ejecting gas from the surface of the wafer to be bonded and measuring the pressure difference between the front section of the measuring gas path and the front section of the reference gas path, the distance between the measuring nozzle and the surface of the wafer to be bonded can be obtained, thereby determining the relative parallelism between the two wafers to be bonded. On the one hand, the measurement method in this embodiment is a non-contact measurement, therefore, it will not cause damage to the wafer surface or generate particulate contamination; on the other hand, the measurement method in this embodiment does not use light, therefore, the measurement accuracy is not affected by the roughness of the wafer surface, and the measurement accuracy can be improved to 10nm, which is far better than optical interferometry.

[0023] Meanwhile, the measuring device in this embodiment is directly applied to the wafer bonding equipment. Therefore, the relative parallelism between two wafers to be bonded can be directly measured during the wafer bonding process. In this way, the measurement results can intuitively reflect the state of the wafer during the bonding process, thus providing more reference value for wafer bonding.

[0024] In addition, since the embodiments of this application adopt a jet-type measurement method, the ejected gas can also sweep away particulate contaminants on the wafer surface, avoiding the adverse effects of particulate contaminants on bonding, thereby improving the bonding quality. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Schematic diagram of the wafer measurement device provided in the embodiments of this application Figure 1 ;

[0027] Figure 2A This is a schematic diagram illustrating the relationship between gas pressure and gap in an embodiment of this application;

[0028] Figure 2B This is a schematic diagram illustrating the relationship between gas flow rate and gap in an embodiment of this application;

[0029] Figure 3 Schematic diagram 2 of the wafer measurement device provided in the embodiments of this application;

[0030] Figure 4 Schematic diagram of the wafer measurement device provided in the embodiments of this application Figure 3 ;

[0031] Figure 5 This is a schematic diagram of the structure of the wafer bonding equipment provided in the embodiments of this application;

[0032] Figure 6A A schematic diagram of the structure of the end of the mechanical shaft in the wafer measurement device provided in the embodiments of this application. Figure 1 ;

[0033] Figure 6B Schematic diagram 2 of the structure of the end of the mechanical shaft in the wafer measurement device provided in the embodiments of this application;

[0034] Figure 7 A schematic diagram of the jetting process of the wafer measurement apparatus provided in the embodiments of this application;

[0035] Figure 8 This is a schematic diagram of the piezoelectric actuator in the wafer measurement device provided in the embodiments of this application;

[0036] Figure 9 A schematic diagram illustrating the compensation operation of the wafer measurement device provided in the embodiments of this application;

[0037] Figure 10 A schematic diagram of the implementation process of the wafer measurement method provided in the embodiments of this application. Figure 1 ;

[0038] Figure 11 Schematic diagram 2 illustrating the implementation flow of the wafer measurement method provided in this application embodiment;

[0039] Figure 12 A schematic diagram of the implementation process of the wafer measurement method provided in the embodiments of this application. Figure 3 ;

[0040] Figure 13 A schematic diagram of the implementation process of the wafer measurement method provided in the embodiments of this application. Figure 4 ;

[0041] Figure 14 A schematic diagram of the implementation process of the wafer measurement method provided in the embodiments of this application. Figure 5 . Detailed Implementation

[0042] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the disclosure of the present application to those skilled in the art.

[0043] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, to avoid confusion with this application, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0044] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0045] It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or parts, these elements, components, areas, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or part from another element, component, area, layer, or part. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or part discussed below may be referred to as a second element, component, area, layer, or part. And the discussion of a second element, component, area, layer, or part does not imply that the first element, component, area, layer, or part necessarily exists in this application.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items. All numerical ranges herein include endpoint values.

[0047] This application provides a wafer measurement device for use in wafer bonding equipment. The wafer measurement device includes a pneumatic measurement module and a data processing module.

[0048] like Figure 1 As shown, the pneumatic measurement module includes: a measuring gas path, a reference gas path, a reference plane, and a differential pressure gauge. The measuring gas path is equipped with a measuring throttle valve, and its end is equipped with a measuring nozzle. The reference gas path is equipped with a reference throttle valve, and its end is equipped with a reference nozzle. Both the beginnings of the measuring and reference gas paths are connected to a gas source. The first end of the differential pressure gauge is connected to the front section of the measuring gas path between the measuring throttle valve and the measuring nozzle; the second end of the differential pressure gauge is connected to the front section of the reference gas path between the reference throttle valve and the reference nozzle.

[0049] Continue to refer to Figure 1 The measuring nozzle is used to eject gas onto the surface of the wafer to be bonded (including the upper and lower wafers). The reference nozzle is used to eject gas onto a reference plane.

[0050] It should be noted that the distance between the measuring nozzle and the surface of the wafer to be bonded (referred to as the gap) affects the gas flow rate through the measuring nozzle. Specifically, as the gap decreases, the obstruction of gas flow by the wafer surface increases, thus reducing the gas flow rate through the measuring nozzle; conversely, as the gap increases, the obstruction of gas flow by the wafer surface decreases, thus increasing the gas flow rate through the measuring nozzle.

[0051] Meanwhile, since the gas flow rate through the measuring nozzle is negatively correlated with the gas pressure at the beginning of the measuring gas path, the gas pressure at the beginning of the measuring gas path can also reflect the size of the gap. Specifically, as the gap decreases, the gas pressure at the beginning of the measuring gas path will increase; correspondingly, as the gap increases, the gas pressure at the beginning of the measuring gas path will decrease.

[0052] Figure 2A The diagram illustrates the relationship between the gas pressure (referred to as pressure) at the front of the measuring gas path and the change in clearance. Figure 2B This illustrates the relationship between the gas flow rate (or simply flow rate) measured at the nozzle and the change in nozzle clearance. For example... Figure 2A and Figure 2B As shown, within a specific gap range, pressure and gap exhibit a linear relationship, and at the same time, flow rate and gap also exhibit a linear relationship.

[0053] In this embodiment of the application, reference is made to Figure 1 A differential pressure gauge is used to measure the pressure difference between the front section of the measuring gas path and the front section of the reference gas path when gas is ejected from both the measuring nozzle and the reference nozzle. In other words, using the distance between the reference nozzle assembly and the reference plane as the standard gap, the pressure difference can reflect the distance between the measuring nozzle and the surface of the wafer to be bonded.

[0054] It should be noted that the wafer measurement device needs to be calibrated before measurement. Specifically, with the measurement throttle valve opening and the reference throttle valve opening as the corresponding preset calibration opening, the differential pressure value curves corresponding to each gap distance between the measuring nozzle and the calibration plane are calibrated (similar to...). Figure 2A (The curve shown) completes the calibration. In subsequent measurements, the opening of the throttle valve and the opening of the reference throttle valve must be consistent with the corresponding preset calibration opening. This allows the gap distance during the measurement process to be calculated by referring to the numerical curve determined during calibration.

[0055] In this embodiment, during the gas ejection process from the measuring nozzle, the distance (i.e., gap) between the measuring nozzle and the surface of the wafer to be bonded is less than 150 μm. This ensures that the gas pressure at the front of the measuring gas path changes significantly with the gap, thereby making the differential pressure gauge measurement more effective. Furthermore, the diameters of both the measuring nozzle and the reference nozzle are less than 500 mm and greater than 0.5 mm, ensuring that the gas flow rate remains within a suitable range.

[0056] In this embodiment of the application, the data processing module is used to determine the relative parallelism between two wafers to be bonded based on the pressure difference.

[0057] In this embodiment, by translating the measuring spray assembly, the measuring nozzles can spray gas onto multiple measuring points on the surface of the wafer to be bonded. Subsequently, the differential pressure gauge can measure the pressure difference corresponding to multiple test points on the surface of the wafer. Here, when the mechanical axis moves from one test point to the next, it must maintain a constant horizontal height; that is, the end of the mechanical axis performs a translating motion. This avoids measurement errors between different test points.

[0058] In this embodiment of the application, reference is made to Figure 7 Multiple measurement points are distributed in a linear or grid pattern on the surface of the wafer to be bonded, which can comprehensively and effectively reflect the condition of the wafer surface.

[0059] In this embodiment of the application, the data processing module performs statistical processing on the measured pressure difference to obtain the global gap data of each of the two wafers to be bonded; wherein, the global gap data includes the gaps corresponding to multiple test points on the surface of the wafers to be bonded.

[0060] Furthermore, the data processing module can perform differential calculations on the global gap data of the two wafers to be bonded to obtain the global relative gap difference data between the two wafers to be bonded. Each value in the global relative gap difference data is obtained by differential calculation between the bonding points on the two wafers to be bonded, thus reflecting the distance between the bonding points on the two wafers to be bonded.

[0061] Furthermore, the data processing module can perform plane fitting on the global relative gap difference data to obtain the minimum mean square error plane. The tilt of the minimum mean square error plane represents the relative parallelism between the two wafers to be bonded. In other words, the smaller the change in the global relative gap difference data, the closer the minimum mean square error plane is to the horizontal plane, and the better the relative parallelism between the two wafers to be bonded.

[0062] In some embodiments of this application, after obtaining the global gap data of each of the two wafers to be bonded, the data processing module can also perform plane fitting on the global gap data of the two wafers to be bonded to obtain the fitting plane of the surface of the two wafers to be bonded; wherein, the shape of the fitting plane characterizes the flatness of the surface of the wafer to be bonded, so as to determine whether the wafer surface has warping or bending, and perform corresponding processing.

[0063] It is understandable that by ejecting gas from the surface of the wafer to be bonded and measuring the pressure difference between the front section of the measuring gas path and the front section of the reference gas path, the distance between the measuring nozzle and the surface of the wafer to be bonded can be obtained, thereby determining the relative parallelism between the two wafers to be bonded. On the one hand, the measurement method in this embodiment is a non-contact measurement, therefore, it will not cause damage to the wafer surface or generate particulate contamination; on the other hand, the measurement method in this embodiment does not use light, therefore, the measurement accuracy is not affected by the roughness of the wafer surface, and the measurement accuracy can be improved to 10nm, which is far better than optical interferometry.

[0064] Meanwhile, the measuring device in this embodiment is directly applied to the wafer bonding equipment. Therefore, the relative parallelism between two wafers to be bonded can be directly measured during the wafer bonding process. In this way, the measurement results can intuitively reflect the state of the wafer during the bonding process, thus providing more reference value for wafer bonding.

[0065] In addition, since the embodiments of this application adopt a jet-type measurement method, the ejected gas can also sweep away particulate contaminants on the wafer surface, avoiding the adverse effects of particulate contaminants on bonding, thereby improving the bonding quality.

[0066] The measurement method provided in this application embodiment has low error, wherein the linear error is less than 0.1 μm and the repeatability error is less than 0.02 μm.

[0067] In some embodiments of this application, such as Figure 5 As shown, the wafer measurement apparatus also includes a mechanical axis. The measurement nozzle, reference nozzle, and reference plane are all located at the end of the mechanical axis (i.e., Figure 5 (The position circled in the middle). This ensures that the measuring nozzle and the reference nozzle operate in a consistent environment, avoiding interference from external environmental factors on the measurement results.

[0068] In this embodiment, the mechanical axis can perform mechanical movements such as translation and rotation. Through these mechanical movements, the mechanical axis can move the measuring nozzle in a region close to the surface of the wafer to be bonded, thereby causing the measuring nozzle to eject gas towards the measuring points on the surface of the wafer to be bonded.

[0069] In some embodiments of this application, such as Figure 3 As shown, there are two measuring gas paths; the first measuring gas path is equipped with a measuring throttle valve 1, and a measuring nozzle a is installed at the end of the first measuring gas path; the second measuring gas path is equipped with a measuring throttle valve 2, and a measuring nozzle b is installed at the end of the second measuring gas path. The first end of the differential pressure gauge branches off into two sub-ends, and a switching valve is installed at the branch position; the two sub-ends of the differential pressure gauge are respectively connected to the front section of the measuring gas path of the two measuring gas paths.

[0070] refer to Figure 5 and Figure 6B The measuring nozzles (i.e., measuring nozzle a and measuring nozzle b) of the two measuring gas paths are positioned opposite each other at the end of the mechanical shaft and face the two wafers to be bonded. During the measurement process, only the end of the mechanical shaft needs to be inserted between the wafers to be bonded.

[0071] Combination Figure 7 The wafer measurement device can control the measurement nozzles to move between the upper and lower wafers, thereby spraying gas at the measurement points on the upper and lower wafers; wherein, the measurement nozzle a facing the upper wafer is used to spray gas onto the upper wafer, while the measurement nozzle b facing the lower wafer is used to spray gas onto the lower wafer.

[0072] In this embodiment of the application, reference is made to Figure 3 During the measurement of the upper wafer, the reference throttle valve and measurement throttle valve 1 are open, while measurement throttle valve 2 is closed. This causes the reference nozzle and measurement nozzle a to eject gas, while measurement nozzle b does not. Similarly, during the measurement of the lower wafer, the reference throttle valve and measurement throttle valve 2 are open, while measurement throttle valve 1 is closed. This causes the reference nozzle and measurement nozzle b to eject gas, while measurement nozzle a does not.

[0073] In some other embodiments of this application, the number of measuring gas paths is one; combined with Figure 5 and Figure 6A The mechanical shaft, through mechanical movements such as rotation and movement, can direct the measuring nozzle of the measuring gas path toward any wafer to be bonded.

[0074] In some embodiments of this application, such as Figure 4 As shown, both the measuring gas path and the reference gas path are connected to the gas source via the main gas path. A flow controller and a gas processor are installed on the main gas path. The flow controller controls the flow rate of the gas in the main gas path; the gas processor filters and cleans the gas in the main gas path. The gas source may include an air pump and an air inlet, wherein the air pump provides power for the ejected gas.

[0075] In some embodiments of this application, the wafer measurement device further includes an adjustment module. The adjustment module is configured to control the stage (chuck) of the wafer bonding equipment to perform a compensation action when the relative parallelism between the two wafers to be bonded exceeds a threshold, until the relative parallelism between the two wafers meets the threshold requirement.

[0076] In some embodiments of this application, such as Figure 8 As shown, the adjustment module includes at least three piezoelectric actuators PZT1, PZT2, and PZT3. These at least three piezoelectric actuators PZT1, PZT2, and PZT3 are positioned along the edge of the stage and drive the stage to perform compensation actions.

[0077] It should be noted that a piezoelectric actuator is a component that uses piezoelectric ceramics as a driving source to generate displacement through the reverse piezoelectric effect. During operation, applying voltage causes the piezoelectric ceramics to displace, thereby driving the stage to perform compensation actions. Using three or more piezoelectric actuators allows the stage to be adjusted to the target plane.

[0078] In this embodiment of the application, combined with Figure 5 and Figure 8 A piezoelectric actuator can be installed between the download stage and the base plate, thereby allowing for fine-tuning of the position of the lower wafer by adjusting the piezoelectric actuator.

[0079] refer to Figure 9 This can drive the download stage to perform a compensation action, causing the lower wafer to rotate around the rotation axis until the relative parallelism between the lower and upper wafers meets the threshold requirement. During the compensation action, the wafer surface height at the rotation axis will remain unchanged.

[0080] In this embodiment of the application, after obtaining the minimum mean square error plane characterizing the relative parallelism, the data processing module can simulate and adjust the minimum mean square error plane to obtain the target horizontal plane; then, the data processing module can determine the geometric operation of adjusting the minimum mean square error plane to the target horizontal plane; then, the data processing module can control the stage of the wafer bonding equipment to perform compensation actions based on the geometric operation.

[0081] It is understood that, in the embodiments of this application, the stage is controlled to perform a compensation action based on the measured relative parallelism, so that the relative parallelism of the two wafers to be bonded meets the threshold requirement. In this way, the bonding quality of the wafers can be guaranteed and bonding damage can be avoided.

[0082] This application also provides a wafer measurement method. For example... Figure 10 As shown, the wafer measurement method includes steps S101 to S104.

[0083] S101. Move the measuring nozzle to a region close to the surface of the wafer to be bonded.

[0084] S102. Open the measuring throttle valve to spray gas from the measuring nozzle onto the surface of the wafer to be bonded, and open the reference throttle valve to spray gas from the reference nozzle onto the reference plane; wherein the opening degree of the measuring throttle valve and the opening degree of the reference throttle valve are consistent with the corresponding preset calibration opening degree.

[0085] S103. The pressure difference between the front section of the measuring gas path and the front section of the reference gas path is measured using a differential pressure gauge.

[0086] S104. Based on the pressure difference, determine the relative parallelism between the two wafers to be bonded.

[0087] In this embodiment of the application, reference is made to Figure 1 The pneumatic measurement module of the wafer measurement apparatus includes: a measurement gas path, a reference gas path, a reference plane, and a differential pressure gauge. The measurement gas path is equipped with a measurement throttle valve, and a measurement nozzle is located at its end. The reference gas path is equipped with a reference throttle valve, and a reference nozzle is located at its end. Both the beginnings of the measurement and reference gas paths are connected to a gas source. The first end of the differential pressure gauge is connected to the front section of the measurement gas path between the measurement throttle valve and the measurement nozzle; the second end of the differential pressure gauge is connected to the front section of the reference gas path between the reference throttle valve and the reference nozzle.

[0088] Continue to refer to Figure 1 The differential pressure gauge is used to measure the pressure difference between the front sections of the measuring gas path and the front sections of the reference gas path when gases are ejected from both the measuring nozzle and the reference nozzle. In other words, using the distance between the reference nozzle assembly and the reference plane as a standard gap, the pressure difference reflects the distance between the measuring nozzle and the surface of the wafer to be bonded. Furthermore, the data processing module can determine the relative parallelism between the two wafers to be bonded based on the pressure difference.

[0089] It should be noted that the wafer measurement device needs to be calibrated before measurement. Specifically, with the measurement throttle valve opening and the reference throttle valve opening as the corresponding preset calibration opening, the differential pressure value curves corresponding to each gap distance between the measuring nozzle and the calibration plane are calibrated (similar to...). Figure 2A (The curve shown) completes the calibration. In subsequent measurements, the opening of the throttle valve and the opening of the reference throttle valve must be consistent with the corresponding preset calibration opening. This allows the gap distance during the measurement process to be calculated by referring to the numerical curve determined during calibration.

[0090] In some embodiments of this application, Figure 10 Following step S104, the wafer measurement method further includes... Figure 11Step S105 is shown. The explanation will be based on each step.

[0091] S105. If the relative parallelism exceeds the threshold, control the stage of the wafer bonding equipment to perform a compensation action until the relative parallelism meets the threshold requirement.

[0092] In this embodiment of the application, combined with Figure 5 and Figure 8 A piezoelectric actuator can be installed between the download stage and the base plate, thereby allowing for fine-tuning of the position of the lower wafer by adjusting the piezoelectric actuator.

[0093] refer to Figure 9 If the relative parallelism exceeds the threshold, the download stage can be driven to perform a compensation action, causing the lower wafer to rotate around the rotation axis until the relative parallelism between the lower wafer and the upper wafer meets the threshold requirement.

[0094] In some embodiments of this application, step S1021 can be used to achieve this. Figure 10 Step S102 is shown. Each step will be explained in detail.

[0095] S1021, Move the measuring nozzle to spray gas onto multiple measuring points on the surface of the wafer to be bonded.

[0096] In this embodiment of the application, reference is made to Figure 1 During the process of gas being ejected from the measuring nozzle to multiple measuring points on the surface of the wafer to be bonded, the differential pressure gauge can measure the pressure difference corresponding to the multiple test points on the surface of the wafer to be bonded. Here, when the mechanical axis moves from one test point to the next test point, it must maintain a constant horizontal height, that is, the end of the mechanical axis performs a translational movement. This can avoid measurement errors between different test points.

[0097] In this embodiment of the application, reference is made to Figure 7 Multiple measurement points are distributed in a linear or grid pattern on the wafer to be bonded, which can comprehensively and effectively reflect the condition of the wafer surface.

[0098] In some embodiments of this application, it can be achieved through Figure 12 The steps S201 to S203 shown are used to achieve the following: Figure 10 Step S104 is shown. The explanation will be provided in conjunction with each step.

[0099] S201. Based on the pressure difference, determine the global gap data of each of the two wafers to be bonded.

[0100] In this embodiment, the global gap data includes the gaps corresponding to multiple test points on the surface of the wafer to be bonded; the gap is the distance between the measuring nozzle and the surface of the wafer to be bonded. Therefore, the global gap data can reflect the overall gap value distribution on the wafer surface, thereby indicating whether the wafer is tilted.

[0101] S202. Perform differential calculation on the global gap data of the two wafers to be bonded to obtain the global relative gap difference data between the two wafers to be bonded.

[0102] In this embodiment, each value in the global relative gap difference data is obtained by differential calculation between the bonding points on the two wafers to be bonded, thus reflecting the distance between the bonding points on the two wafers to be bonded.

[0103] S203. Perform plane fitting on the global relative gap difference data to obtain the minimum mean square error plane; wherein, the tilt of the minimum mean square error plane characterizes the relative parallelism between the two wafers to be bonded.

[0104] In this embodiment, the tilt of the minimum mean square error plane characterizes the relative parallelism between the two wafers to be bonded. In other words, the smaller the change in the global relative gap difference data, the closer the minimum mean square error plane is to the horizontal plane, and the better the relative parallelism between the two wafers to be bonded.

[0105] In some embodiments of this application, in Figure 12 Following step S201, the wafer measurement method further includes... Figure 13 Step S204 is shown. The explanation will follow each step.

[0106] S204. Perform plane fitting on the global gap data of the two wafers to be bonded to obtain the fitting plane of the surface of the two wafers to be bonded; wherein, the shape of the fitting plane characterizes the flatness of the surface of the wafers to be bonded.

[0107] In this embodiment of the application, by performing planar fitting on the global gap data of the two wafers to be bonded, a fitting plane characterizing the flatness can be obtained. In this way, it can be determined whether the wafer surface has warping or bending, and corresponding processing can be performed.

[0108] In some embodiments of this application, in Figure 12 Following step S203, the wafer measurement method further includes... Figure 14 Steps S301 to S303 are shown. Each step will be explained in detail.

[0109] S301. Simulate and adjust the minimum mean square error plane to obtain the target horizontal plane.

[0110] S302. Determine the geometric operations for adjusting the plane from the minimum mean square error plane to the target horizontal plane.

[0111] S303, based on geometric operations, controls the stage of the wafer bonding equipment to perform compensation actions.

[0112] In this embodiment, the tilt of the minimum mean square error plane characterizes the relative parallelism between two wafers to be bonded. That is, the smaller the change in the global relative gap difference data, the closer the minimum mean square error plane is to a horizontal plane, and the better the relative parallelism between the two wafers to be bonded. Therefore, the process of adjusting the minimum mean square error plane to the target horizontal plane simulates the process of adjusting the relative parallelism. The geometric operations in the simulation adjustment can be used to control the stage of the wafer bonding equipment to perform corresponding compensation actions, for example, referring to... Figure 8 and Figure 9 It can control the piezoelectric actuator to drive the download stage to perform compensation actions, so that the lower wafer rotates around the rotation axis until the relative parallelism between the lower wafer and the upper wafer meets the threshold requirement.

[0113] This application also provides a wafer bonding device, such as... Figure 5 As shown, the wafer bonding equipment includes a wafer measurement device. Figure 5 The diagram shows the mechanical shaft and part of the gas pipe in the wafer measurement device. The wafer measurement device includes the technical features described in the above embodiments.

[0114] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0115] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined to obtain new method embodiments without conflict. The features disclosed in the several product embodiments provided in this application can be arbitrarily combined to obtain new product embodiments without conflict. The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined to obtain new method or device embodiments without conflict.

[0116] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes 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.

Claims

1. A wafer measurement device, applied to wafer bonding equipment, characterized in that, The wafer measurement device includes: a pneumatic measurement module, a data processing module, and a mechanical axis; the pneumatic measurement module includes: a measurement gas path, a reference gas path, a reference plane, and a differential pressure gauge; The measurement gas path consists of two lines, each equipped with a measurement throttle valve and a measurement nozzle at its end. A reference gas path is equipped with a reference throttle valve and a reference nozzle at its end. The beginnings of both the measurement and reference gas paths are connected to a gas source. The measurement nozzle, reference nozzle, and reference plane are all located at the end of the mechanical shaft. The measurement nozzles of the two measurement gas paths are positioned opposite each other at the end of the mechanical shaft and face the two wafers to be bonded. The differential pressure gauge has two branch ends at its first end, and a switching valve is provided at each branch position; the two branch ends of the differential pressure gauge are respectively connected to the front section of the two measuring gas paths; the second end of the differential pressure gauge is connected to the front section of the reference gas path between the reference throttle valve and the reference nozzle. The measuring nozzle is used to spray gas onto the surface of the wafer to be bonded; The reference nozzle is used to eject gas toward the reference plane; The differential pressure gauge is used to measure the pressure difference between the front sections of the two measuring gas paths and the front section of the reference gas path when gas is ejected from the measuring nozzle and the reference nozzle. The data processing module is used to determine the relative parallelism between the two wafers to be bonded based on the pressure difference.

2. The wafer measuring apparatus according to claim 1, characterized in that, The mechanical shaft moves the measuring nozzle in a region close to the surface of the wafer to be bonded through mechanical motion.

3. The wafer measuring apparatus according to claim 2, characterized in that, The number of the measuring gas path is one; The mechanical shaft moves mechanically to orient the measuring nozzle of the measuring gas path toward any of the wafers to be bonded.

4. The wafer measuring apparatus according to claim 1, characterized in that, Both the measuring gas path and the reference gas path are connected to the gas source through the main gas path; A flow controller and a gas processor are installed on the main gas line; The flow controller is used to control the flow rate of gas in the main gas path; The gas processor is used to filter and clean the gas in the main gas path.

5. The wafer measuring apparatus according to claim 1, characterized in that, The wafer measurement device further includes: an adjustment module; The adjustment module is used to control the stage of the wafer bonding equipment to perform a compensation action when the relative parallelism exceeds the threshold, until the relative parallelism meets the threshold requirement.

6. The wafer measuring apparatus according to claim 5, characterized in that, The adjustment module includes at least three piezoelectric actuators; The at least three piezoelectric actuators are disposed at the edge of the stage and drive the stage to perform the compensation action.

7. The wafer measuring apparatus according to claim 1, characterized in that, During the process of the gas being ejected from the measuring nozzle, the distance between the measuring nozzle and the surface of the wafer to be bonded is less than 150 μm; The diameters of both the measuring nozzle and the reference nozzle are less than 500 mm and greater than 0.5 mm.

8. A wafer measurement method, characterized in that, The wafer measurement method includes: The measuring nozzle is moved to a region close to the surface of the wafer to be bonded; the wafer to be bonded includes an upper wafer and a lower wafer to be bonded; The measurement throttle valve is opened, causing the measurement nozzle to spray gas onto the surface of the wafer to be bonded. Simultaneously, the reference throttle valve is opened, causing the reference nozzle to spray gas onto a reference plane. The opening degrees of both the measurement throttle valve and the reference throttle valve are consistent with their respective preset calibration opening degrees. The step of spraying gas onto the surface of the wafer to be bonded by the measurement nozzle includes: controlling the measurement nozzle to move between the upper and lower wafers, spraying gas onto the surfaces of both wafers. The pressure difference between the measuring gas path front section and the reference gas path front section is measured using a differential pressure gauge; wherein, the measuring gas path front section is located between the measuring throttle valve and the measuring nozzle; and the reference gas path front section is located between the reference throttle valve and the reference nozzle. Determining the relative parallelism between the two wafers to be bonded based on the pressure difference includes: determining the global gap data for each of the two wafers to be bonded based on the pressure difference; wherein the global gap data includes the gaps corresponding to multiple test points on the surface of the wafers to be bonded; the gap is the distance between the measuring nozzle and the surface of the wafers to be bonded; performing differential calculation on the global gap data of the two wafers to be bonded to obtain global relative gap difference data between the two wafers to be bonded; performing plane fitting on the global relative gap difference data to obtain a minimum mean square error plane; wherein the tilt of the minimum mean square error plane characterizes the relative parallelism between the two wafers to be bonded.

9. The wafer measurement method according to claim 8, characterized in that, After determining the relative parallelism between the two wafers to be bonded, the wafer measurement method further includes: If the relative parallelism exceeds the threshold, the stage of the wafer bonding equipment is controlled to perform a compensation action until the relative parallelism meets the threshold requirement.

10. The wafer measurement method according to claim 8, characterized in that, The method of spraying gas from the measuring nozzle onto the surface of the wafer to be bonded includes: The measuring nozzle is shifted so that it sprays gas onto multiple measuring points on the surface of the wafer to be bonded; wherein the multiple measuring points are distributed in a linear or grid pattern on the wafer to be bonded.

11. The wafer measurement method according to claim 8, characterized in that, After obtaining the global gap data for each of the two wafers to be bonded, the wafer measurement method further includes: Plane fitting is performed on the global gap data of the two wafers to be bonded to obtain the fitting plane of the surfaces of the two wafers to be bonded; wherein the shape of the fitting plane characterizes the flatness of the surface of the wafer to be bonded.

12. The wafer measurement method according to claim 8, characterized in that, After obtaining the minimum mean square error plane, the wafer measurement method further includes: The minimum mean square error plane is simulated and adjusted to obtain the target horizontal plane; Determine the geometric operation to adjust the plane from the minimum mean square error plane to the target horizontal plane; Based on the aforementioned geometric operations, the stage of the wafer bonding equipment is controlled to perform compensation actions.

13. A wafer bonding apparatus, characterized in that, The wafer bonding equipment includes the wafer measurement device as described in any one of claims 1 to 7.

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