Wafer measuring device and method and wafer bonding equipment

Abstract

The invention relates to the field of integrated circuits, and discloses a wafer measuring device and method and wafer bonding equipment. The wafer measuring device comprises an air pressure type measuring module and a data processing module. The air pressure type 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 gas circuit, and a measuring nozzle is arranged at the tail end of the measuring gas circuit. A reference throttle valve is arranged on the reference gas path, and a reference nozzle is arranged at the tail end of the reference gas path. The starting end of the measuring gas circuit and the starting end of the reference gas circuit are both 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; and 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.

Description

Technical Field

[0001] The present application relates to the field of integrated circuits, and in particular to a wafer measurement device, method and wafer bonding equipment. Background Art

[0002] In the process of integrated circuit manufacturing, in order to manufacture micro-electromechanical systems or realize chip packaging, two manufactured wafers are directly bonded together, which is called W2W (Wafer to Wafer) bonding technology. The bonding process is to align the two wafers and then bond them together, and then anneal the contact surface of the wafers to solidify and achieve complete bonding of the two wafers.

[0003] However, during the bonding process, the relative parallelism between the two wafers will directly affect the post-bonding results, and thus affect the yield and final performance of the product. If the relative parallelism between the two wafers is poor, it may lead to incomplete bonding or reduced bonding strength. At the same time, it may also cause defects at the wafer edge or bonding interface, such as particles, debris, scratches, etc. Therefore, it is very important to determine the relative parallelism between the two wafers during the W2W bonding process.

[0004] In the existing W2W bonding technology, before bonding, the wafer will be sent to a dedicated measurement device to test the flatness, thereby avoiding the poor flatness of the wafer affecting the relative parallelism during the bonding process. Common methods for testing flatness include contact probe method or optical interference test. Among them, the contact probe method uses a mechanical probe to directly contact the surface of the wafer, which may cause damage to the patterned devices on the wafer surface and produce particle contamination, so it is not suitable for high-precision bonding processes; although the optical interference method does not directly contact the wafer, the reflectivity of the wafer surface is not 100%, and there are stacks of different material layers inside, resulting in the "surface" detected by the light is not the surface of the wafer, but below the surface, with a deviation of ±0.05 to 0.15um, and the deviation range will vary with different wafer products. In addition, the wafer after measurement may also undergo deposition, cleaning, activation and other treatments before bonding, and its wafer flatness may change. Therefore, the method of determining relative parallelism in the prior art has many shortcomings and needs to be improved. Summary of the invention

[0005] In view of this, the embodiments of the present application provide a wafer measurement device, method and wafer bonding equipment, which can avoid damage to the wafer surface or particle contamination and improve measurement accuracy.

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

[0007] The embodiment of the present application provides a wafer measurement device, which is applied to 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 starting end of the measurement gas path and the starting end of 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, and the reference nozzle is provided at the end of the reference gas path; The differential pressure gauge is connected to a front section of a measuring gas path between the reference throttle valve and the measuring nozzle; the second end of the differential pressure gauge is connected to a front section of a reference gas path between the reference throttle valve and the reference nozzle; the measuring nozzle is used to spray gas toward the surface of the wafer to be bonded; the reference nozzle is used to spray gas toward the reference plane; the 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 the measuring nozzle and the reference nozzle spray gas; 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 the present application, the wafer measurement device also includes: a mechanical axis; the measurement nozzle, the reference nozzle and the reference plane are all arranged at the end of the mechanical axis; the mechanical axis moves the measurement nozzle in an area close to the surface of the wafer to be bonded through mechanical movement.

[0009] In some embodiments of the present application, the number of the measuring gas circuits is two; the measuring nozzles of the two measuring gas circuits are arranged at the ends of the mechanical axis opposite to each other and respectively face the two wafers to be bonded; the first end of the differential pressure gauge branches into two sub-ends, and a switching valve is provided at the branching position; the two sub-ends of the differential pressure gauge are respectively connected to the front sections of the measuring gas circuits of the two measuring gas circuits.

[0010] In some embodiments of the present application, the number of the measuring gas path is one; the mechanical axis makes the measuring nozzle of the measuring gas path face any one of the wafers to be bonded through mechanical movement.

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

[0012] In some embodiments of the present 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 value until the relative parallelism meets the threshold requirement.

[0013] In some embodiments of the present application, the adjustment module includes: at least three piezoelectric actuators; the at least three piezoelectric actuators are arranged at the edge of the carrier to drive the carrier to perform the compensation action.

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

[0015] An embodiment of the present application also provides a wafer measurement method, which includes: moving a measurement nozzle to an area close to the surface of a wafer to be bonded; opening a measurement throttle valve to allow the measurement nozzle to spray gas toward the surface of the wafer to be bonded, and opening a reference throttle valve to allow the reference nozzle to spray gas toward a reference plane; wherein the opening of the measurement throttle valve and the opening of the reference throttle valve are respectively consistent with corresponding preset calibrated openings; measuring the pressure difference between a front section of the measurement gas path and a front section of the reference gas path by a differential pressure gauge; wherein the front section of the measurement gas path is located between the measurement throttle valve and the measurement nozzle; and the front section of the reference gas path is located between the reference throttle valve and the reference nozzle; based on the pressure difference, determining the relative parallelism between the two wafers to be bonded.

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

[0017] In some embodiments of the present application, making the measuring nozzle spray gas toward the surface of the wafer to be bonded includes: translating the measuring nozzle so that the measuring nozzle sprays gas toward multiple measuring points on the surface of the wafer to be bonded; wherein the multiple measuring points are distributed in a linear or grid shape on the wafer to be bonded.

[0018] In some embodiments of the present application, the relative parallelism between the two wafers to be bonded is determined based on the pressure difference, including: based on the pressure difference, determining the global gap data of each of the two wafers to be bonded; wherein the global gap data includes: 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; 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 inclination of the minimum mean square error plane characterizes the relative parallelism between the two wafers to be bonded.

[0019] In some embodiments of the present 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 fitting planes of the surfaces of the two wafers to be bonded; wherein the shape of the fitting plane characterizes the flatness of the surfaces of the wafers to be bonded.

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

[0021] An embodiment of the present application also provides a wafer bonding device, which includes the wafer measuring device described in the above scheme.

[0022] It is understandable that by spraying gas on 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, and then the relative parallelism between the two wafers to be bonded can be determined. On the one hand, the measurement method in the embodiment of the present application is non-contact measurement, so it will not cause damage to the wafer surface or produce particle contamination; on the other hand, the measurement method in the embodiment of the present application does not use light, so the measurement accuracy is not affected by the roughness of the wafer surface, and the measurement accuracy can be improved to 10nm, which is much better than optical interference testing.

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

[0024] In addition, since the embodiment of the present application adopts a jet-type measurement method, the ejected gas can also purge the particulate contaminants on the surface of the wafer to avoid the adverse effects of the particulate contaminants on bonding, thereby improving the quality of bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 Schematic diagram of the structure of the wafer measurement device provided in the embodiment of the present application Figure 1 ;

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

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

[0029] Figure 3 A second structural diagram of a wafer measurement device provided in an embodiment of the present application;

[0030] Figure 4 Schematic diagram of the structure of the wafer measurement device provided in the embodiment of the present application Figure 3 ;

[0031] Figure 5 A schematic diagram of the structure of a wafer bonding device provided in an embodiment of the present application;

[0032] Fig. 6A A schematic diagram of the structure of the end of the mechanical axis in the wafer measurement device provided in the embodiment of the present application Figure 1 ;

[0033] Figure 6B A second structural schematic diagram of the end of a mechanical axis in a wafer measurement device provided in an embodiment of the present application;

[0034] Figure 7 A schematic diagram of the air jetting process of the wafer measurement device provided in an embodiment of the present application;

[0035] Figure 8 A schematic diagram of the structure of a piezoelectric actuator in a wafer measurement device provided in an embodiment of the present application;

[0036] Fig. 9 A schematic diagram of a compensation action of a wafer measurement device provided in an embodiment of the present application;

[0037] Fig.10 Schematic diagram of the implementation process of the wafer measurement method provided in the embodiment of the present application Figure 1 ;

[0038] Fig.11 Schematic diagram 2 of the implementation process of the wafer measurement method provided in the embodiment of the present application;

[0039] Fig.12 Schematic diagram of the implementation process of the wafer measurement method provided in the embodiment of the present application Figure 3 ;

[0040] Fig.13 Schematic diagram of the implementation process of the wafer measurement method provided in the embodiment of the present application Figure 4 ;

[0041] Fig.14 Schematic diagram of the implementation process of the wafer measurement method provided in the embodiment of the present application Figure 5 . DETAILED DESCRIPTION

[0042] The exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope disclosed in the present application to those skilled in the art.

[0043] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0044] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0045] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part. When the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has a first element, component, region, layer or part.

[0046] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present application. When used herein, the singular "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "composition" and / or "comprising" when used in this specification determine the existence of the features, integers, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items. All numerical ranges herein include endpoint values.

[0047] The embodiment of the present application provides a wafer measuring device applied to a wafer bonding device. The wafer measuring device includes: a pneumatic measuring module and a data processing module.

[0048] like Figure 1 As shown, the air pressure measurement module includes: a measuring gas circuit, a reference gas circuit, a reference plane and a differential pressure gauge. Among them, a measuring throttle valve is provided on the measuring gas circuit, and a measuring nozzle is provided at the end of the measuring gas circuit; a reference throttle valve is provided on the reference gas circuit, and a reference nozzle is provided at the end of the reference gas circuit; the beginning of the measuring gas circuit and the beginning of the reference gas circuit are both connected to the gas source. The first end of the differential pressure gauge is connected to the front section of the measuring gas circuit 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 circuit between the reference throttle valve and the reference nozzle.

[0049] Continue to refer Figure 1 The measuring nozzle is used to spray gas toward the surface of the wafers to be bonded (including the upper wafer and the lower wafer). The reference nozzle is used to spray gas toward the 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) will affect the gas flow through the measuring nozzle. Specifically, as the gap decreases, the surface of the wafer to be bonded will hinder the gas flow more, so the gas flow through the measuring nozzle will decrease; correspondingly, as the gap increases, the surface of the wafer to be bonded will hinder the gas flow less, so the gas flow through the measuring nozzle will increase.

[0051] At the same time, since the gas flow through the measuring nozzle is negatively correlated with the gas pressure at the front section of the measuring gas path, the value of the gas pressure at the front section of the measuring gas path can also reflect the size of the gap. Specifically, as the gap decreases, the gas pressure at the front section of the measuring gas path will increase; correspondingly, as the gap increases, the gas pressure at the front section of the measuring gas path will decrease.

[0052] Figure 2A The relationship between the gas pressure (referred to as pressure) and the gap at the front section of the measuring gas path is shown. Figure 2B The figure shows the relationship between the gas flow rate (referred to as flow rate) through the measuring nozzle and the gap. Figure 2A and Figure 2B As shown, within a specific gap range, the pressure and the gap show a linear relationship, and at the same time, the flow rate and the gap also show a linear relationship.

[0053] In the present application examples, reference Figure 1 The 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 the measuring nozzle and the reference nozzle are spraying gas. In other words, taking the distance between the reference nozzle 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 before the measurement is carried out, the wafer measurement device needs to be calibrated. Specifically, when the opening of the measuring throttle valve and the opening of the reference throttle valve are the corresponding preset calibration openings, the differential pressure value curve corresponding to each gap distance between the measuring nozzle and the calibration plane is calibrated (similar to Figure 2A In the subsequent measurement process, the opening of the measured throttle valve and the opening of the reference throttle valve need to be consistent with the corresponding preset calibration openings, so that the gap distance in the measurement process can be calculated by referring to the numerical curve determined by the calibration work.

[0055] In the embodiment of the present application, during the process of the measuring nozzle ejecting gas, the distance (i.e., the gap) between the measuring nozzle and the surface of the wafer to be bonded is less than 150 μm, so that the gas pressure in the front section of the measuring gas path can be ensured to change more obviously with the change of the gap, thereby making the measurement of the differential pressure gauge more effective. In addition, the diameters of the measuring nozzle and the reference nozzle are both less than 500 mm and greater than 0.5 mm, so that the gas flow rate can be ensured to be within an appropriate range.

[0056] In an embodiment of the present 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 the embodiment of the present application, by translating the measurement spray group, the measurement nozzle can spray gas to multiple measurement points on the surface of the wafer to be bonded, and then 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, the horizontal height needs to remain unchanged, that is, the end of the mechanical axis performs a translational action, so that measurement errors between different test points can be avoided.

[0058] In the present application examples, reference Figure 7 , multiple measuring points are distributed in a linear or grid shape on the surface of the wafer to be bonded, so that the condition of the surface of the wafer to be bonded can be fully and effectively reflected.

[0059] In an embodiment of the present application, the data processing module counts and processes 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 wafer to be bonded.

[0060] Furthermore, the data processing module can 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; wherein each value in the global relative gap difference data is obtained by performing differential calculation between the bonding points on the two wafers to be bonded, and thus can reflect 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; wherein the inclination of the minimum mean square error plane represents the relative parallelism between the 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 the horizontal plane, and the better the relative parallelism between the two wafers to be bonded.

[0062] In some embodiments of the present 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, respectively, to obtain the fitting planes of the surfaces of the two wafers to be bonded; wherein the shape of the fitting plane characterizes the flatness of the surfaces of the wafers to be bonded, so that it can be determined whether warping or bending occurs on the wafer surface, and corresponding processing can be performed.

[0063] It is understandable that by spraying gas on 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, and then the relative parallelism between the two wafers to be bonded can be determined. On the one hand, the measurement method in the embodiment of the present application is non-contact measurement, so it will not cause damage to the wafer surface or produce particle contamination; on the other hand, the measurement method in the embodiment of the present application does not use light, so the measurement accuracy is not affected by the roughness of the wafer surface, and the measurement accuracy can be improved to 10nm, which is much better than optical interference testing.

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

[0065] In addition, since the embodiment of the present application adopts a jet-type measurement method, the ejected gas can also purge the particulate contaminants on the surface of the wafer to avoid the adverse effects of the particulate contaminants on bonding, thereby improving the quality of bonding.

[0066] The measurement method provided in the embodiment of the present application has a relatively low error, wherein the linear error can be less than 0.1 μm and the repeatability error can be less than 0.02 μm.

[0067] In some embodiments of the present application, Figure 5 As shown, the wafer measurement device also includes: a mechanical axis. The measurement nozzle, the reference nozzle and the reference plane are all arranged at the end of the mechanical axis (i.e. Figure 5 In this way, the measuring nozzle and the reference nozzle can operate in the same environment, avoiding interference of external environmental factors on the measurement results.

[0068] In the embodiment of the present application, the mechanical axis can perform mechanical movements such as translation, rotation, etc. The mechanical axis can move the measurement nozzle in a region close to the surface of the wafer to be bonded through mechanical movement, so that the measurement nozzle can spray gas toward the measurement point on the surface of the wafer to be bonded.

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

[0070] refer to Figure 5 and Figure 6B The measuring nozzles of the two measuring gas paths (i.e., measuring nozzle a and measuring nozzle b) are arranged at the ends of the mechanical axis opposite to each other and facing the two wafers to be bonded respectively. During the measurement process, it is only necessary to extend the end of the mechanical axis between the wafers to be bonded.

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

[0072] In the present application examples, reference Figure 3 In the process of measuring the upper wafer, the reference throttle valve and the measurement throttle valve 1 are opened, while the measurement throttle valve 2 is closed, so that the reference nozzle and the measurement nozzle a will spray gas, while the measurement nozzle b will not spray gas. Correspondingly, in the process of measuring the lower wafer, the reference throttle valve and the measurement throttle valve 2 are opened, while the measurement throttle valve 1 is closed, so that the reference nozzle and the measurement nozzle b will spray gas, while the measurement nozzle a will not spray gas.

[0073] In other embodiments of the present application, the number of the measuring gas path is one; Figure 5 and Fig. 6A The mechanical axis can make the measuring nozzle of the measuring gas path point to any wafer to be bonded through mechanical movements such as rotation and movement.

[0074] In some embodiments of the present application, Figure 4 As shown, the measuring gas circuit and the reference gas circuit are both connected to the gas source through the main gas circuit. A flow controller and a gas processor are provided on the main gas circuit. The flow controller is used to control the flow of the gas in the main gas circuit; the gas processor is used to filter and clean the gas in the main gas circuit. 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 the present application, the wafer measurement device further includes: an adjustment module. The adjustment module is used to control the chuck of the wafer bonding device to perform a compensation action when the relative parallelism between the two wafers to be bonded exceeds a threshold value, until the relative parallelism between the two wafers to be bonded meets the threshold requirement.

[0076] In some embodiments of the present application, Figure 8 As shown, the adjustment module includes: at least three piezoelectric actuators PZT1, PZT2 and PZT3. At least three piezoelectric actuators PZT1, PZT2 and PZT3 are arranged at the edge of the stage to drive the stage to perform compensation action.

[0077] It should be noted that a piezoelectric actuator is a component that uses piezoelectric ceramics as a driving source and generates displacement through the reverse piezoelectric effect. When working, the piezoelectric ceramics are displaced by applying voltage, thereby driving the stage to perform compensation actions. Setting three or more piezoelectric drivers can drive the stage to adjust to the target plane.

[0078] In the present application embodiment, combined Figure 5 and Figure 8 , a piezoelectric actuator can be set between the unloading platform and the base plate, so that the position of the lower wafer can be fine-tuned by adjusting the piezoelectric actuator.

[0079] refer to Fig. 9 , the unloading platform can be driven to perform compensation action, 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. During the compensation action, the height of the wafer surface at the rotation axis will remain unchanged.

[0080] In an embodiment of the present application, after obtaining the minimum mean square error plane that characterizes the relative parallelism, the data processing module can simulate the adjustment of 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 carrier of the wafer bonding equipment to perform compensation action based on the geometric operation.

[0081] It can be understood that in the embodiment of the present 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] The present application also provides a wafer measurement method. Fig.10 As shown, the wafer measurement method includes steps S101 to S104.

[0083] S101 , moving the measurement nozzle to an area close to the surface of the wafer to be bonded.

[0084] S102, opening the measuring throttle valve to make the measuring nozzle spray gas toward the surface of the wafer to be bonded, and opening the reference throttle valve to make the reference nozzle spray gas toward the reference plane; wherein the opening of the measuring throttle valve and the opening of the reference throttle valve are respectively consistent with the corresponding preset calibrated openings.

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

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

[0087] In the present application examples, reference Figure 1 The pneumatic measurement module of the wafer measurement device includes: a measurement gas circuit, a reference gas circuit, a reference plane and a differential pressure gauge. Among them, a measurement throttle valve is provided on the measurement gas circuit, and a measurement nozzle is provided at the end of the measurement gas circuit; a reference throttle valve is provided on the reference gas circuit, and a reference nozzle is provided at the end of the reference gas circuit; the beginning of the measurement gas circuit and the beginning of the reference gas circuit are both connected to the gas source. The first end of the differential pressure gauge is connected to the front section of the measurement gas circuit 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 circuit between the reference throttle valve and the reference nozzle.

[0088] Continue to refer Figure 1 The 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 the measuring nozzle and the reference nozzle spray gas. In other words, taking the distance between the reference nozzle group 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. 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 before the measurement is carried out, the wafer measurement device needs to be calibrated. Specifically, when the opening of the measuring throttle valve and the opening of the reference throttle valve are the corresponding preset calibration openings, the differential pressure value curve corresponding to each gap distance between the measuring nozzle and the calibration plane is calibrated (similar to Figure 2A In the subsequent measurement process, the opening of the measured throttle valve and the opening of the reference throttle valve need to be consistent with the corresponding preset calibration openings, so that the gap distance in the measurement process can be calculated by referring to the numerical curve determined by the calibration work.

[0090] In some embodiments of the present application, Fig.10 After step S104, the wafer measurement method further includes Fig.11The step S105 shown will be described in combination with each step.

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

[0092] In the present application embodiment, combined Figure 5 and Figure 8 , a piezoelectric actuator can be set between the unloading platform and the base plate, so that the position of the lower wafer can be fine-tuned by adjusting the piezoelectric actuator.

[0093] refer to Fig. 9 , when the relative parallelism exceeds the threshold, the unloading platform can be driven to perform a compensation action 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.

[0094] In some embodiments of the present application, step S1021 can be used to implement Fig.10 The step S102 shown will be described in combination with each step.

[0095] S1021 , translate the measuring nozzle to make the measuring nozzle spray gas toward a plurality of measuring points on the surface of the wafer to be bonded.

[0096] In the present application examples, reference Figure 1 In the process of the measuring nozzle spraying gas 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, the horizontal height needs to remain unchanged, that is, the end of the mechanical axis performs a translational action, so that measurement errors between different test points can be avoided.

[0097] In the present application examples, reference Figure 7 , multiple measurement points are distributed in a linear or grid shape on the wafer to be bonded, so that the surface condition of the wafer to be bonded can be fully and effectively reflected.

[0098] In some embodiments of the present application, Fig.12 Steps S201 to S203 are shown to achieve Fig.10 The step S104 shown will be described in combination with each step.

[0099] S201 , determining global gap data of two wafers to be bonded based on the pressure difference.

[0100] In the embodiment of the present application, 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 gap value distribution of the entire wafer surface, and thus whether the position of the wafer is tilted.

[0101] S202 , 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.

[0102] In the embodiment of the present application, each value in the global relative gap difference data is obtained by performing a differential calculation between the bonding points on the two wafers to be bonded, and thus can reflect the distance between the bonding points on the two wafers to be bonded.

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

[0104] In the embodiment of the present application, the inclination of the minimum mean square error plane represents the relative parallelism between the two wafers to be bonded. That is, the smaller the change in the global relative gap difference data is, 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 is.

[0105] In some embodiments of the present application, Fig.12 After step S201, the wafer measurement method further includes Fig.13 The step S204 shown will be described in combination with each step.

[0106] S204 , performing plane fitting on the global gap data of the two wafers to be bonded respectively to obtain fitting planes of the surfaces of the two wafers to be bonded; wherein the shapes of the fitting planes represent the flatness of the surfaces of the wafers to be bonded.

[0107] In the embodiment of the present application, by performing plane 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 warping or bending occurs on the wafer surface, and corresponding processing can be performed.

[0108] In some embodiments of the present application, Fig.12 After step S203, the wafer measurement method further includes Fig.14 Steps S301 to S303 are shown. Each step will be described in combination.

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

[0110] S302: Determine a geometric operation for adjusting the minimum mean square error plane to the target horizontal plane.

[0111] S303 , based on the geometric operation, controlling the stage of the wafer bonding equipment to perform compensation action.

[0112] In the embodiment of the present application, the inclination of the minimum mean square error plane represents the relative parallelism between the two wafers to be bonded. That is, the smaller the change in the global relative gap difference data is, 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 is. 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 operation in the simulated adjustment can be used to control the carrier of the wafer bonding equipment to perform the corresponding compensation action. For example, referring to Figure 8 and Fig. 9 , the piezoelectric actuator can be controlled to drive the unloading stage to perform a compensation action, 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] The present 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 mechanical axis and part of the air pipe in the wafer measurement device are shown in FIG. 1 . The wafer measurement device includes the technical features of the above-mentioned embodiments.

[0114] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0115] The serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments. The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments. The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments. The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0116] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A wafer measuring device, applied to wafer bonding equipment, characterized in that: The wafer measurement device comprises: a pneumatic measurement module and a data processing module; the pneumatic measurement module comprises: a measurement gas path, a reference gas path, a reference plane and a differential pressure gauge; The measuring gas path is provided with a measuring throttle valve, and the end of the measuring gas path is provided with a measuring nozzle; the reference gas path is provided with a reference throttle valve, and the end of the reference gas path is provided with a reference nozzle; the starting end of the measuring gas path and the starting end of the reference gas path are both 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; The measuring nozzle is used to spray gas toward the surface of the wafer to be bonded; The reference nozzle is used to spray gas toward the reference plane; The 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 the measuring nozzle and the reference nozzle spray gas; 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 measurement device according to claim 1, characterized in that: The wafer measurement device further includes: a mechanical axis; The measuring nozzle, the reference nozzle and the reference plane are all arranged at the end of the mechanical axis; The mechanical axis moves the measurement nozzle in a region close to the surface of the wafer to be bonded through mechanical movement.

3. The wafer measurement device according to claim 2, characterized in that: The number of the measuring gas paths is two; The measuring nozzles of the two measuring gas paths are arranged at the ends of the mechanical axis opposite to each other and respectively face 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 branching position; the two sub-ends of the differential pressure gauge are respectively connected to the front sections of the measuring gas paths of the two measuring gas paths.

4. The wafer measurement device according to claim 2, characterized in that: The number of the measuring gas path is one; The mechanical axis moves mechanically so that the measuring nozzle of the measuring gas path faces any one of the wafers to be bonded.

5. The wafer measurement device according to claim 1, characterized in that: The measuring gas circuit and the reference gas circuit are both connected to a gas source through a main gas circuit; The main gas circuit is provided with a flow controller and a gas processor; The flow controller is used to control the flow of the gas in the main gas path; The gas processor is used to filter and clean the gas in the main gas path.

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

7. The wafer measurement device according to claim 6, characterized in that: The regulating module includes: at least three piezoelectric actuators; The at least three piezoelectric actuators are arranged at the edge of the carrier to drive the carrier to perform the compensation action.

8. The wafer measurement device according to claim 1, characterized in that: During the process of the measuring nozzle ejecting gas, the distance between the measuring nozzle and the surface of the wafer to be bonded is less than 150 μm; The diameters of the measuring nozzle and the reference nozzle are both less than 500 mm and greater than 0.5 mm.

9. A wafer measurement method, characterized in that: The wafer measurement method comprises: moving the measurement nozzle to an area close to the surface of the wafer to be bonded; Opening the measuring throttle valve so that the measuring nozzle sprays gas toward the surface of the wafer to be bonded, and opening the reference throttle valve so that the reference nozzle sprays gas toward the reference plane; wherein the opening of the measuring throttle valve and the opening of the reference throttle valve are respectively consistent with the corresponding preset calibration openings; The pressure difference between the front section of the measuring gas path and the front section of the reference gas path is measured by a differential pressure gauge; wherein the front section of the measuring gas path is located between the measuring throttle valve and the measuring nozzle; and the front section of the reference gas path is located between the reference throttle valve and the reference nozzle; Based on the pressure difference, the relative parallelism between the two wafers to be bonded is determined.

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

11. The wafer measurement method according to claim 9, characterized in that: The step of causing the measuring nozzle to spray gas toward the surface of the wafer to be bonded comprises: The measuring nozzle is translated to make the measuring nozzle spray gas toward a plurality of measuring points on the surface of the wafer to be bonded; wherein the plurality of measuring points are distributed in a linear or grid shape on the wafer to be bonded.

12. The wafer measurement method according to claim 9, characterized in that: Based on the pressure difference, determining the relative parallelism between the two wafers to be bonded comprises: Based on the pressure difference, determining the global gap data of each of the two wafers to be bonded; wherein the global gap data includes: gaps corresponding to a plurality of 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; 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; A plane fitting is performed on the global relative gap difference data to obtain a minimum mean square error plane; wherein the inclination of the minimum mean square error plane represents the relative parallelism between the two wafers to be bonded.

13. The wafer measurement method according to claim 12, characterized in that: After obtaining the global gap data of 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 respectively to obtain fitting planes of the surfaces of the two wafers to be bonded; wherein the shapes of the fitting planes represent the flatness of the surfaces of the wafers to be bonded.

14. The wafer measurement method according to claim 12, characterized in that: 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 a geometric operation for adjusting the minimum mean square error plane to the target horizontal plane; Based on the geometric operation, the stage of the wafer bonding equipment is controlled to perform a compensation action.

15. A wafer bonding device, characterized in that: The wafer bonding equipment comprises the wafer measurement device according to any one of claims 1 to 8.

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