Bond strength test method and device

Abstract

The embodiments of the present application disclose a bonding strength testing method and device, which relate to the field of semiconductor technology, can reduce testing costs, achieve the effect of repeatable testing operations, and improve the accuracy of bonding strength testing of integrated structures. The bonding strength testing method includes: providing an integrated structure formed by bonding a die and a wafer. Determine the edge of the bonding interface between the die and the wafer. A groove structure is formed on the surface of the wafer close to the die at the edge of the bonding interface; the edge of the die is located on the side of the opening of the groove structure perpendicular to the plane of the wafer. Pull the die based on the groove structure and determine the bonding strength between the die and the wafer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a bonding strength testing method and device. Background Art

[0002] In the related art, the methods used for bonding strength testing, such as crack propagation diffusion method, four-point bending delamination method, straight pull method, etc., are usually one-time and destructive, which is not conducive to being widely used in the process flow of bonding strength detection, and the process cost is high; it is also not suitable for bonding strength testing of bonded integrated structures of different sizes; and the accuracy and repeatability of bonding strength testing also need to be improved. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a bonding strength testing method and device to solve at least one problem existing in the background technology, which can reduce the testing cost, achieve the effect of repeatable testing operation, and improve the accuracy of bonding strength testing of integrated structures.

[0004] To achieve the above purpose, the technical solution of this application is implemented as follows:

[0005] On the one hand, an embodiment of the present application provides a method for testing bonding strength. The method includes providing an integrated structure formed by bonding a die and a wafer. Determining the edge of the bonding interface between the die and the wafer. A groove structure is formed on the surface of the wafer on one side close to the die at the edge of the bonding interface; the edge of the die is located on the side of the opening of the groove structure perpendicular to the plane of the wafer. Pull the die based on the groove structure and determine the bonding strength between the die and the wafer.

[0006] In some examples, the step of pulling the die based on the groove structure and determining the bonding strength between the die and the wafer includes: a test hook is inserted into the groove structure and contacts a surface of one side of the die to pull the die. The pulling force applied to the die is increased at intervals of a first time length, and the pulling force value of the die is recorded, and a pulling force value curve is drawn according to the multiple pulling force values. When the pulling force value suddenly decreases, the maximum pulling force value among the multiple pulling force values ​​is determined to be the bonding strength.

[0007] In some examples, the step of pulling the tube core based on the groove structure and determining the bonding strength between the tube core and the wafer includes: a test hook extends into the groove structure and contacts a surface of one side of the tube core to pull the tube core. The pulling force value of the pulling force on the tube core is recorded at each second time interval, and image information of the bonding interface between the tube core and the wafer is obtained at each second time interval. The pulling force value when the bonding interface between the tube core and the wafer is separated is determined as the bonding strength.

[0008] In some examples, the groove structure formed at the edge of the bonding interface on the surface of the wafer on the side close to the tube core includes: irradiating the edge of the bonding interface with a laser having a pulse width less than a preset value along a direction having an angle with the plane of the wafer to form the groove structure; the preset value is the minimum pulse width of the laser that is related to the size of the tube core or affects the performance of the tube core and the wafer.

[0009] In some examples, the laser irradiates the edge of the bonding interface, including: continuously scanning the laser at the edge of the bonding interface to form an annular groove surrounding the tube core; or, scanning the laser at intervals at the edge of the bonding interface to form at least two grooves surrounding the tube core; two of the at least two grooves are located on a center line of the tube core.

[0010] In some examples, the integrated structure includes a plurality of the dies distributed in different areas of the wafer.

[0011] The method comprises: irradiating the edges of the bonding interfaces between the plurality of tube dies and the wafer with a laser to form a plurality of the groove structures. Pulling out the plurality of tube dies respectively based on the groove structures, and determining the bonding strengths between the plurality of tube dies and the wafer respectively. Determining the bonding strength between the tube die and the wafer according to the average value of the plurality of bonding strengths.

[0012] In some examples, determining the edge of the bonding interface between the die and the wafer includes: using an optical lens to obtain the edge of the bonding interface between the die and the wafer; and / or obtaining alignment parameters during the bonding process between the die and the wafer, and determining the edge of the bonding interface between the die and the wafer according to the structure of the die.

[0013] In some examples, the method further includes: forming a protective layer on a side of the die away from the wafer based on position information of the die; the protective layer at least covers an edge region of a bonding interface between the die and the wafer.

[0014] In some examples, forming a protective layer on the side of the tube core away from the wafer includes: determining the position and size of the tube core. Using laser cutting protection liquid, forming the protective layer on the surface of the tube core away from the wafer; one protective layer is used to cover one tube core.

[0015] In some examples, after forming the groove structure, the method further includes: removing the protective layer; and / or, flushing the groove structure to remove residues in the groove structure.

[0016] In some examples, providing an integrated structure formed by bonding the die and the wafer includes: providing the die and the wafer with hybrid bonding; and / or providing the die and the wafer with bonding without forming interconnect leads between the die and the wafer.

[0017] Compared with the method of first making a groove structure and then bonding the die to the wafer, the test method provided by the present application can avoid the bonding process causing the die material to be filled into the groove structure, affecting the subsequent position of the clamp. For example, the clamp cannot directly contact the die, but contacts the material in the groove. The connection strength between these materials and the wafer causes the bonding strength characterized by the tensile force of the test to include stress values ​​other than the bonding strength between the die and the wafer, reducing the accuracy of the test bond and strength. In this way, the above-mentioned method for testing the bonding strength based on the integrated structure of the die and wafer that have been bonded forms a groove structure on the integrated structure, and the opening of the groove structure extends from the edge of the die to the side surface of the die, which can facilitate the clamp to extend from the opening of the groove and contact with the bottom of the die. The tensile force acts directly on the die, and the bonding strength between the die and the wafer can be tested, reducing the influence of the tensile force on other structures on the test accuracy, and improving the accuracy of the test bond strength between the die and the wafer. Furthermore, the testing method provided in the present application can be applied to different integrated structures formed by various bonding methods, has a simple process, and expands the scope of application.

[0018] On the other hand, an embodiment of the present application provides a device for testing bonding strength. The device for testing bonding strength is used for the test method provided in any of the above examples. The device includes: a test base, a processing control unit and a display unit. The test base is used to fix the integrated structure formed by the bonding of the wafer and the die. The processing control unit is used to obtain edge information of the bonding interface between the die and the wafer, form a groove structure along the edge of the bonding interface, and pull the die through a clamp and record the tension value information; determine the bonding strength between the die and the wafer based on the tension value. The display unit is coupled to the processing control unit, and is used to display the tension value information, and to display the bonding strength information.

[0019] In some examples, the processing control unit is further used to form a protective layer on a side of the tube die away from the wafer based on position information of the tube die, and / or to rinse the integrated structure after forming the groove structure and perform a drying process.

[0020] The beneficial effects of the device for testing bonding strength provided in the embodiment of the present application are the same as the beneficial effects of the method for testing bonding strength provided in any of the above examples, and will not be repeated here.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a process for testing bonding strength provided in an embodiment of the present application Figure 1 ;

[0023] Figure 2 A schematic diagram of an integrated structure provided in one embodiment of the present application;

[0024] Figure 3 A schematic cross-sectional view of a wafer and a die of an integrated structure provided by an embodiment of the present application along the AA line;

[0025] Figure 4 A schematic diagram of a process for testing bonding strength provided in an embodiment of the present application Figure 2 ;

[0026] Figure 5 (a) in ~ Figure 5 (f) is a schematic diagram of the structural flow of a bonding strength testing method provided in an embodiment of the present application;

[0027] Figure 6 for Figure 5 (d) is an enlarged schematic diagram of the local structure G;

[0028] Figure 7 A schematic diagram of a groove structure provided in one embodiment of the present application;

[0029] Figure 8 Another schematic diagram of the structure of the groove structure provided in one embodiment of the present application;

[0030] Fig. 9 A schematic diagram of a process for testing bonding strength provided in an embodiment of the present application Figure 3 ;

[0031] Fig.10 A schematic diagram of the structure of a device for testing bonding strength provided in one embodiment of the present application. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] 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.

[0035] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers.

[0036] 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.

[0037] Spatial relationship terms such as "under", "below", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0038] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence 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.

[0039] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0040] Wafer bonding technology refers to the process of tightly bonding two wafers together through chemical and physical effects. After the wafers are bonded, the atoms at the interface react under the action of external forces to form covalent bonds and become one, and the bonding interface reaches a specific bonding strength. Among them, wafer bonding technology can be divided into four categories, including adhesive and anodic bonding, direct wafer bonding, metal wafer bonding and hybrid bonding (HB).

[0041] In wafer bonding technology, bonding strength is an important technical indicator to characterize the bonding effect. If the bonding strength is too low, the two wafers bonded to each other are likely to crack during processing, leading to failure. Therefore, it is necessary to test the bonding strength of the bonded wafers to evaluate whether the bonding effect of the bonded wafers meets the requirements of the subsequent process.

[0042] For example, the bonding process can be divided into wafer to wafer (W2W) bonding, chip to wafer (C2W) bonding, die to wafer (C2C) bonding and chip to chip (C2C) bonding according to the bonding object. Different bonding objects can choose appropriate test methods to perform bonding strength tests.

[0043] It should be noted that chip and die can refer to the same structure (the names are interchangeable), or die can be a chip that is not packaged. Different levels of chip structures are set according to needs. For example, chip, die and wafer are three different levels of chip structures. The examples provided in this application do not impose specific restrictions on the structure of chip and die, and they can all be tested using subsequent testing methods. Subsequent examples all use "die" for illustrative purposes.

[0044] In the related art, the crack propagation diffusion method, four-point bending layering method, straight pull method and other methods are usually used to test the bonding strength. However, these methods are mostly used to test the bonding strength between wafer-level chips. Moreover, these methods are destructive testing methods. After the test is completed, the two bonded chips tested cannot be used for functional implementation, which makes it impossible to accurately judge whether the bonding strength in the actual integrated structure is consistent with the bonding strength in the test.

[0045] For example, the crack propagation diffusion method includes using an interference method to test the crack length, forming an initial crack in advance, and judging the bonding strength based on the size of the crack. This requires that the bonding strength can only be judged when the size of the crack being tested is large (for example, the crack size is significantly larger than the size of the entire bonded chip). If the size of the two bonded chips is small (for example, a few millimeters to tens of millimeters), the crack size is not easy to grasp and the bonding strength cannot be accurately judged. Especially after the chip is thinned (for example, a die-level chip), the thinned chip itself is easy to break, resulting in the main influencing factor of the size of the crack being obtained being the bonding strength or the material of the thinned chip itself. In this way, in the scenario where the die-level chip is bonded to the wafer-level chip, the crack propagation diffusion method cannot accurately determine the bonding strength.

[0046] The four-point bending delamination method is mainly used to test the crack resistance and fracture behavior of stacked materials in stacked structures when subjected to interlayer stress. Due to the large size difference between core-level chips and wafer-level chips, the bonding interface between the two cannot be tested for bonding strength using the four-point bending delamination method.

[0047] In the process of testing the bond strength by the direct-pull method, it is usually necessary to modify the connection structure at the bonding interface of the two chips (such as interconnection leads or beam leads, etc.) to increase the bonding curvature, so that the test hook can smoothly extend into the connection structure or the bottom of the chip, and then perform a tensile test. The magnitude of the pulling force indicates the bonding strength of the two chips. If it is based on the bonding technology of advanced packaging, in the bonding structure between the core-level chip and the wafer-level chip, there is no gap at the bonding interface between the core-level chip and the wafer-level chip, and it is impossible to implement the means for the test hook to extend into the bottom of the core-level chip. In addition, even if the fixture and the core-level chip are glued together and then tested by tension, after the test is completed, the fixture and the tested core-level chip cannot be reused. They are all disposable testing methods, which are not conducive to being widely used in the bonding strength testing process in the semiconductor process flow. Moreover, even if the bonding strength of the tested integrated structure meets the requirements, since the tested integrated structure is damaged and cannot be applied to actual products (it is not local damage, but the entire test wafer is damaged), it is impossible to guarantee whether the bonding strength of the new integrated structure in the actual product meets the requirements.

[0048] Based on this, an embodiment of the present application provides a bonding strength testing method, which can improve the testing accuracy of bonding strength and reduce the damage rate of the bonded wafer structure caused by the bonding testing means, which is conducive to being widely used in the bonding test of integrated structures.

[0049] like Figure 1 As shown, in some embodiments, the bonding strength testing method includes: S100, S200, S300 and S400.

[0050] S100: Figure 2 As shown, an integrated structure 100 formed by bonding a die 10 and a wafer 20 is provided.

[0051] For example, the integrated structure 100 provided in the present application may be the same semiconductor substrate or a heterogeneous composite integrated structure. The semiconductor substrate of the die 10 included in the heterogeneous composite integrated structure is different from the semiconductor substrate of the wafer 20, and heterogeneous refers to the different semiconductor substrates of the two. For example, the material of the semiconductor substrate may include one or more of silicon Si, gallium nitride GaN, silicon carbide SiC, and indium phosphide InP.

[0052] For example, the die 10 may be an unpackaged integrated circuit structure for forming a radio frequency device chip, a power device chip or a silicon photonic chip. The embodiment of the present application does not limit the specific functional type of the die 10 .

[0053] The wafer 20 may include a silicon photonic chip. The size of the wafer 20 is quite different from that of the tube core 10. Based on the structure of the conductive pillars on the wafer 20 that can meet the requirements of different-sized tube cores 10 for electrical connection, a plurality of tube cores 10 of different sizes can be bonded on the wafer 20.

[0054] It is understandable that bonding is generally performed on the entire plane of the tube core 10 and the wafer 20. The interface of the bonding between the two may include contacting non-conductive materials and conductive structures to achieve hybrid bonding; it may also include conductive structures to achieve electrical connection, and no bonding is performed on the contacting non-conductive materials. Among them, based on the advantages of hybrid bonding technology that allows solder-free bonding, it can reduce the interconnection spacing, reduce the thickness of the bonding interface, etc., and the prepared tube core 10 (or chip Chip) is bonded to the wafer 20, which can simplify the process of preparing the integrated structure 100, while improving the alignment accuracy and coupling efficiency of the tube core 10 (or chip Chip) and the wafer 20. The present application does not specifically limit the bonding method of the integrated structure 100, and the example test method provided in the present application can be applied to the integrated structure 100 formed by any bonding method.

[0055] In addition, considering that the thickness of the tube core 10 may affect the bonding strength, in order to reflect the bonding strength between the tube core 10 and the wafer 20 in the actual product, the tube core 10 may refer to a thinned structure.

[0056] In some examples, a hybrid bonded die 10 and wafer 20 are provided. And / or, a bonded die 10 and wafer 20 are provided without forming interconnect wires between the die 10 and wafer 20 .

[0057] Before bonding, the surface of the die 10 may be polished by a chemical mechanical polishing process to improve the surface flatness of the die 10 so as to improve the bonding tightness in the subsequent process of achieving hybrid bonding through the contact surface of the die 10 and the wafer 20 .

[0058] The chip-wafer bonding process is used to sequentially bond multiple dies 10 to the wafer 20. For example, firstly a die 10 is bonded to the wafer 20 after an alignment process, and then a second die 10 is bonded to the wafer 20 after an alignment process, and so on, and the dies 10 are sequentially bonded to the areas on the wafer 20 where the dies 10 are required to be arranged. In this way, the bonding strength of different areas of the wafer 20 can be tested as required to improve the accuracy of the bonding strength test.

[0059] S200 : Determine the edge M of the bonding interface between the die 10 and the wafer 20 .

[0060] It is understood that the “bonding interface” refers to the surface where the die 10 and the wafer 20 are in contact and bonded. The “edge of the bonding interface” refers to the edge of the surface where the die 10 and the wafer 20 are in contact, and may also refer to the position of the side edge of the die 10 on the wafer 20. For example, Figure 2 and Figure 3 As shown, the shape of the “edge of the bonding interface” is a closed figure (that is, it can be the shape of the tube core 10), and M is used to represent the position of the edge of the bonding interface in subsequent examples.

[0061] In some examples, such as Figure 4 As shown, S200 includes S210 and / or S220.

[0062] S210: Using an optical lens to obtain an edge M of the bonding interface between the die 10 and the wafer 20 .

[0063] For example, the optical lens can be a structure for acquiring image information. For example, the optical lens can be a structure used by a camera or a microscope or other equipment to collect images. In this way, the edge M of the bonding interface between the die 10 and the wafer can be directly observed through the optical lens, or an image of the bonding interface between the die 10 and the wafer 20 can be collected, and the edge M of the bonding interface between the die 10 and the wafer 20 can be intuitively determined from the image. This application does not make specific restrictions on this, and it can be selected according to the specific operation process of the test method.

[0064] And / or, S220 : acquiring alignment parameters during the bonding process of the die 10 and the wafer 20 , and determining an edge M of the bonding interface between the die 10 and the wafer 20 according to the structure of the die 10 .

[0065] For example, based on the alignment parameters of the die 10 on the wafer 20 determined during the bonding process of the die 10 and the wafer 20 (such as the position information of the conductive structure bonded between the two), and combined with the shape and size of the die 10, the coordinate position of the die 10 on the wafer 20 and the edge M of the bonding interface between the die 10 and the wafer 20 can be determined.

[0066] The information of the alignment parameters during the bonding process between the die 10 and the wafer 20 can be transmitted from the device for implementing the bonding to the device for testing the bonding strength; or the operator can obtain the information from the device for implementing the bonding and input it into the input interface of the device for testing the bonding strength to control the device for testing the bonding strength to perform the test operation. This application does not impose any specific restrictions on the transmission method of the alignment parameters during the bonding process between the die 10 and the wafer 20, and it can be set according to the specific implementation requirements of the test method.

[0067] In some examples, such as Figure 4 As shown, before etching the groove structure 21 , the testing method further includes S500 .

[0068] S500: Based on the position information of the tube core 10, a protective layer 30 is formed on the side of the tube core 10 away from the wafer 20. The protective layer 30 at least covers the edge area of ​​the bonding interface between the tube core 10 and the wafer 20. The protective layer 30 can improve the cutting quality of the cutting groove structure 21, and can also reduce the adverse effect of the deformation of the tube core 10 caused by laser irradiation on the tube core 10 on the magnitude of the tension applied to the deformed position of the tube core 10 later.

[0069] For example, the protective layer 30 covers at least the edge area of ​​the bonding interface between the die 10 and the wafer 20, including: the protective layer 30 can cover the edge area of ​​the bonding interface between the die 10 and the wafer 20, for example, the protective layer 30 only surrounds the edge of the die 10 and is located on the wafer 20. Considering that the laser irradiates the edge of the bonding interface between the die 10 and the wafer 20, the protective layer 30 covering the edge area of ​​the bonding interface between the die 10 and the wafer 20 can protect the position of the die 10 and the wafer 20 irradiated by the laser, and can improve the quality of laser cutting.

[0070] Or, if Figure 5 As shown in (c) in the figure, multiple protective layers 30 are formed, and one protective layer 30 is used to cover one tube core 10. The protective layer 30 can cover the side surface of the tube core 10 away from the wafer 20 and extend to the edge area of ​​the bonding interface between the tube core 10 and the wafer 20. The size of different protective layers 30 can be adjusted according to the size of the tube core 10 it covers. In this way, multiple protective layers 30 can protect the tube core 10 respectively, which is conducive to improving the protection effect against lasers.

[0071] Alternatively, the protection layer 30 may be a whole layer and cover a plurality of tube cores 10. This is beneficial to the process operation.

[0072] like Figure 4 As shown, in some examples, S500 includes S510 and S520.

[0073] S510 : Determine the position and size of the die 10 .

[0074] For example, Figure 4 As shown, the position and size of the die 10 can be determined according to the above steps S210 and / or S220, and the specific method will not be repeated here.

[0075] S520: Figure 5 As shown in (b), a laser cutting protection liquid is used to form a protection layer 30 on the surface of the tube core 10 away from the wafer 20. One protection layer 30 is used to cover one tube core 10.

[0076] It should be noted that the laser cutting protection fluid is in liquid state. During the laser cutting process, the laser cutting protection fluid can effectively block the thermal energy of the laser, reduce the heat generated during the laser cutting process, reduce the thermal impact on the cutting surface, and improve cutting accuracy.

[0077] For example, the amount of the laser cutting protection liquid is set according to the size of the tube core 10 so that the laser cutting protection liquid can cover one tube core 10 .

[0078] In addition, in some examples, the protective layer 30 may be a solid layer structure formed by a photolithography + etching process. For example, the material of the protective layer 30 may be an insulating material such as silicon nitride or silicon oxide.

[0079] For example, the thickness of the protective layer 30 ranges from 1 micron to 2 microns. For example, the thickness of the protective layer 30 is 1 micron, 1.5 microns or 2 microns. In addition, the thickness of the protective layer 30 can be increased according to actual requirements such as the structure of the tube core 10 and the application scenario.

[0080] S300: Figure 5 As shown in (c) and (d) in FIG. 1 , a groove structure 21 is formed on the surface of the wafer 20 close to the tube core 10 at the edge M of the bonding interface. The edge of the tube core 10 is located on the side of the opening of the groove structure 21 perpendicular to the plane of the wafer 20.

[0081] The edge of the tube core 10 is located on one side of the groove structure 21 along the direction perpendicular to the plane of the wafer 20, which can mean that the edge of the tube core 10 is located above the opening of the groove structure 21, or that the edge of the tube core 10 is located at the groove depth of the groove structure 21 extending to the bottom of the tube core 10, as long as the groove structure 21 can facilitate the hook of the clamp in the subsequent process to extend into the groove structure 21 and contact the bottom surface of the tube core 10. It can be understood that "above", "below" and "bottom" are based on Figure 6 The description method of the structural position of the local G of the integrated structure 100 shown in FIG.

[0082] In some examples, such as Figure 4 As shown, S300 includes S310 .

[0083] S310: along a direction having an angle with the plane of the wafer 20, a laser having a pulse width less than a preset value is used to irradiate the edge M of the bonding interface to form a groove structure 21. The preset value is the minimum pulse width of the laser that is related to the size of the die or affects the performance of the die 10 and the wafer 20.

[0084] It is understandable that the smaller the pulse width of the laser, the higher the frequency of the laser, and the greater the laser energy. In this way, the effect of laser etching per unit time is better, for example, the edge after etching is smoother, the particle size produced by etching is smaller, etc. Among them, the smaller the laser spot, the better the etching effect. For example, picosecond laser is used for etching. The frequency of picosecond laser is 100 kHz to 1000 kHz, and the wavelength can be 355nm, 405 nm, 488 nm, 532 nm, 780 nm, 800 nm, 1030 nm, 1064 nm, etc.

[0085] For example, Figure 6 As shown, the extending direction of the plane where the wafer 20 is located is X, and the direction perpendicular to the plane where the wafer 20 is located is Y. The direction having an angle with the plane where the wafer 20 is located can be direction Y, or direction P having an angle with both X and Y.

[0086] The laser irradiates the edge M of the bonding interface along the direction P. By controlling the time for which the laser irradiates the same position of the edge M of the bonding interface, the depth of the etched groove structure 21 can be adjusted. Figure 6 In the cross-sectional view of the groove structure 21 shown, the depth of the groove structure 21 extends along the laser irradiation direction P, and the opening of the formed groove is relatively large. The edge of the tube core 10 is located on one side of the groove structure 21 along the direction Y perpendicular to the plane of the wafer 20, that is, the edge of the tube core 10 is suspended above the groove structure 21, so that the pull hook of the clamp in the subsequent process steps can extend into the groove structure 21 and contact the tube core 10 to pull the tube core 10.

[0087] In some examples, such as Figure 7 As shown, S310 includes: continuously scanning the edge M of the bonding interface with a laser to form an annular groove 211 surrounding the tube core 10 .

[0088] The shape of the annular groove 211 in a top view is related to the shape of the tube core 10. The shapes of the tube cores 10 with different functions and structures can be the same or different. The present application does not impose any specific restrictions on the shape of the tube core 10. It is sufficient to form an annular groove structure 21 along the edge of the tube core 10. For example, the shape of the tube core 10 is rectangular (see Figure 7 ), the shape of the annular groove 211 in a top view is a rectangle. The shape of the tube core 10 is an irregular polygon (not shown in the figure), and the shape of the annular groove 211 in a top view is the same as the shape of the tube core 10.

[0089] Based on the annular groove 211 , when a clamp is used to clamp the tube core 10 in the subsequent process steps, the clamp can use any position on the edge of the tube core 10 as a force point while ensuring that the tube core 10 is subjected to balanced force, thereby facilitating the clamp's clamping operation.

[0090] In other examples, such as Figure 8 As shown, S310 includes: laser scanning the edge M of the bonding interface at intervals to form at least two grooves 211 surrounding the tube core 10. Two of the at least two grooves 211 are located on a center line Q of the tube core 10 (for example Figure 8 on Q1 or Q2 in the circuit.

[0091] For example, based on the shape of the tube core 10, a plurality of grooves 211 are formed and arranged at intervals around the tube core 10. A center line Q of the tube core 10 includes, when the shape of the tube core 10 is a regular polygon, the center line Q is the symmetry axis of the tube core 10; when the shape of the tube core 10 is an irregular polygon, the center line Q is a line starting from a point on the edge of the tube core 10 and passing through the center of gravity of the tube core 10.

[0092] For example, Figure 8 As shown, the tube core 10 is in the shape of a rectangle, and a groove 211 is formed on each of the four sides of the rectangle, and two opposite grooves are located on the center line (or axis of symmetry) of the tube core 10. In this way, considering the influence of different force-bearing positions of the tube core 10 on the magnitude of the pulling force, in the operation of clamping the tube core 10 with a fixture in the subsequent process steps, the clamp hook extends into the two grooves 211 located on the same center line Q1 or Q2, so that the tube core 10 is subjected to a balanced force, which is conducive to improving the accuracy of detecting the bonding strength between the tube core 10 and the wafer 20 under the action of the pulling force.

[0093] During the laser irradiation of the edge M of the bonding interface, the groove structure 21 can be etched by fixing the orientation of the laser light source and translating or rotating the integrated structure 100, or by adjusting the position of the laser light source. This application does not limit this and can be set according to actual needs.

[0094] In some examples, such as Figure 4 As shown, before pulling out the tube die 10, the testing method further includes S600. S600 includes S610 and / or S620.

[0095] For example, S610: Figure 5 As shown in (e) in FIG. 1 , the protective layer 30 is removed.

[0096] According to step S500 in the above example, the protective layer 30 can be in a solid state or in a liquid state.

[0097] For example, when the protection layer 30 is in a solid state, the protection layer 30 may be removed by a lift-off process.

[0098] For another example, when the protective layer 30 is in a liquid state, the protective layer 30 can be removed by a deionized water rinsing process.

[0099] For example, S620: Figure 5 As shown in (e) in FIG. 1 , the groove structure 21 is rinsed to remove the residue in the groove structure 21 .

[0100] For example, when the protection layer 30 is in a liquid state, the integrated structure 100 may be rinsed with deionized water to remove residues in the protection layer 30 and the groove structure 21 .

[0101] For another example, when the protection layer 30 is in a solid state, the residue in the groove structure 21 may be removed first, and then the protection layer 30 may be removed using an organic solvent according to the material properties of the protection layer 30 .

[0102] It should be explained that the above-mentioned removal of the residue in the protective layer and the groove structure 21 can be achieved simultaneously by the same process step. The above two examples of the present application illustrate two removal methods based on different objects to be removed, and do not limit the implementation to two steps.

[0103] Furthermore, the present application does not limit the order of steps S610 and S620. After removing the residues in the protective layer 30 and / or the groove structure 21, the integrated structure 100 may be dried, for example, by rotating the integrated structure 100 for drying.

[0104] S400 : Pull out the tube die 10 based on the groove structure 21 , and determine the bonding strength between the tube die 10 and the wafer 20 .

[0105] For example, Figure 5 As shown in (f), the die 10 is pulled by the clamp 200, and the hook 210 of the clamp 200 extends into the groove structure 21 and contacts one side surface of the die 10. The clamp clamps the die 10 and pulls the die 10 along the direction Y perpendicular to the plane of the wafer 20. The magnitude of the pulling force can represent the bonding strength between the die 10 and the wafer 20.

[0106] In some examples, such as Fig. 9 As shown, S400 includes: S410~S430.

[0107] S410 : The test hook 210 extends into the groove structure 21 and contacts a surface of one side of the tube core 10 , and pulls the tube core 10 .

[0108] like Figure 5 As shown in (f), the test hook 210 of the fixture 200 moves in a direction perpendicular to the plane where the wafer 20 is located to pull the tube core 10. In this way, by setting the pulling direction of the tube core 10, the force on the tube core 10 is balanced, and the test accuracy of the bonding strength between the tube core 10 and the wafer 20 is improved.

[0109] S420: increasing the tension applied to the tube core 10 at intervals of a first time length, recording the tension value of the tension applied to the tube core 10, and drawing a tension value curve according to the multiple tension values.

[0110] For example, a tension sensor can be used to record the tension value of the tube core 10 at intervals of a first time length. The value of the first time length can be adjusted according to the tension applied to the tube core 10 (or the tension that the tube core 10 can withstand), so that multiple tension values ​​can be tested in the process of uniformly increasing tension. For example, the first time length is 1 second. Then, a tension value curve is drawn based on multiple tension values, so as to intuitively judge the change of tension value.

[0111] S430: Determine that, in the case where the tension value suddenly decreases, the maximum tension value among the plurality of tension values ​​is the key strength.

[0112] For example, when the die 10 and the wafer 20 are not separated, as the tension applied to the die 10 increases, it indicates that the current tension value does not reach the bonding strength between the die 10 and the wafer 20. When the die 10 and the wafer 20 are separated, the tension value drops sharply. In this way, the bonding strength between the die 10 and the wafer 20 is obtained according to the largest tension value among the multiple tension values ​​obtained. For example, based on the tension value curve determined in the above steps, in the interval where the tension value curve drops suddenly, the largest tension value is the bonding strength between the die 10 and the wafer 20.

[0113] In other examples, such as Fig. 9 As shown, S400 includes: S440~S460.

[0114] S440 : The test hook extends into the groove structure 21 and contacts a surface of one side of the tube core 10 , and pulls out the tube core 10 .

[0115] like Figure 5 As shown in (f), the test hook 210 of the fixture 200 moves in a direction perpendicular to the plane where the wafer 20 is located to pull the tube core 10. In this way, by setting the pulling direction of the tube core 10, the force on the tube core 10 is balanced, and the test accuracy of the bonding strength between the tube core 10 and the wafer 20 is improved.

[0116] S450: recording the tension value of the tube die 10 at every second time interval, and acquiring image information of the bonding interface between the tube die 10 and the wafer 20 at every second time interval.

[0117] For example, a tension sensor can be used to obtain the tension value of the tension applied to the die 10 every second time period, and an optical lens can be used to obtain image information of the bonding interface between the die 10 and the wafer 20 every second time period. The image information of the bonding interface can display the status of the die 10 and the wafer 20 under the current tension in real time.

[0118] The value of the second time length can be adjusted according to the tension applied to the tube core 10 (or the tension that the tube core 10 can withstand), so that multiple tension values ​​can be tested in the process of uniformly increasing tension. For example, the second time length is 1 second.

[0119] It should be explained that the “second time length” and the “first time length” are used to distinguish the data collection time in the embodiments of different process flows, and do not limit the data of the “second time length” and the “first time length” to be different, that is, the values ​​of the “second time length” and the “first time length” can be the same.

[0120] S460: Determine the tension value when the bonding interface between the die 10 and the wafer 20 is separated as the bonding strength.

[0121] Based on the image information of the bonding interface between the die 10 and the wafer 20 obtained in S450, it is possible to determine when the die 10 and the wafer 20 are separated. For example, in the image information of the bonding interface between the die 10 and the wafer 20 obtained by an optical lens, when the die 10 and the wafer 20 are separated, the gap between the two can be represented as a white area in the image, and the operator can intuitively observe the separation of the two and determine the tension value obtained while obtaining the image.

[0122] Based on the above test method example, you can combine Figure 5 (a) in ~ Figure 5 (f) in further describes the test process. In some examples, such as Figure 5 As shown in FIG. 2 (a), the integrated structure 100 includes a plurality of dies 10 distributed in different regions of a wafer 20 .

[0123] The “multiple dies 10 in different regions” may include multiple dies with smaller spacing distances arranged in a dense region of a wafer bonding chip corresponding to an actual semiconductor product, and multiple dies 10 with larger spacing distances arranged in other regions.

[0124] The bonding strength test method includes: irradiating the edges M of the bonding interfaces between the plurality of tube dies 10 and the wafer 20 with laser light to form a plurality of groove structures 21. One groove structure 21 is formed for one tube die 10.

[0125] The groove structure 21 may include an annular closed groove 211; or may include a plurality of spaced grooves 211, and at least two of the plurality of spaced grooves 211 are located on the center line of the tube core 10. For example, the groove structure 21 includes two grooves 211, and the two grooves 211 are located on the center line of the tube core 10.

[0126] Based on the groove structure 21, multiple tube cores 10 are pulled out respectively, and the bonding strengths of the multiple tube cores 10 and the wafer 20 are determined respectively. For example, after the clamp 200 pulls out a tube core 10 and measures the pulling force value representing the bonding strength, the current tube core 10 is released. Then, the clamp 200 can clamp other tube cores 10 by translating or rotating the integrated structure 100; or, the position of the clamp 200 can be moved so that the clamp can clamp other tube cores 10. And so on, the bonding strengths of all tube cores 10 and the wafer 20 are determined.

[0127] Finally, the bonding strength between the die 10 and the wafer 20 is determined based on the average value of the multiple bonding strengths. In this way, the bonding strength between the die 10 and the wafer 20 in different regions can be determined based on the multiple die 10 located in different regions, and the bonding strength of the entire wafer 20 relative to the die 10 at any position can be determined by calculating the average value of the multiple bonding strengths, thereby improving the accuracy of the tested bonding strength.

[0128] For example, in different integration scenarios, the sizes of different dies 10 will change to adapt to changes in the number and size of integrated chips. Among them, in the integrated structure 100 that bonds multiple dies 10, the sizes of multiple dies 10 can be different. In this way, based on the structure of the conductive column on the wafer 20 that can meet the electrical connection of dies 10 of different sizes, multiple dies 10 of different sizes can be bonded on the wafer 20. By testing the bonding strength of dies 10 of different sizes located in different areas, the accuracy of testing the bonding strength of dies 10 of different sizes and wafers 20 can be improved.

[0129] Furthermore, in the above scenario of obtaining the average value of the bonding strength of multiple dies 10 , the bonding methods of multiple dies 10 and wafer 20 are set to be the same, so as to facilitate the detection of the bonding strength of the dies 10 and wafer 20 for different bonding methods.

[0130] Compared to the method of first making the groove structure 21 and then bonding the tube core 10 and the wafer 20, the means provided in the present application can avoid the bonding process causing the material of the tube core 10 to be filled into the groove structure 21, affecting the subsequent position of the clamp. For example, the clamp cannot directly contact the tube core 10, but contacts the material in the groove structure 21. The viscosity between these materials and the wafer 20 causes the bonding strength characterized by the tensile force of the test to include stress values ​​other than the bonding strength between the tube core 10 and the wafer 20, thereby reducing the accuracy of testing the bonding strength between the tube core 10 and the wafer 20. In this way, the above-mentioned method for testing the bonding strength based on the integrated structure 100 of the already bonded tube core 10 and the wafer 20 forms a groove structure 21 on the integrated structure 100, and the opening of the groove structure 21 extends from the edge of the tube core 10 to the side surface of the tube core 10, which can facilitate the fixture to extend from the opening of the groove structure 21 and contact the bottom of the tube core 10. The tension acts directly on the tube core 10, and the bonding strength between the tube core 10 and the wafer 20 can be tested, reducing the influence of the tension on other structures on the test accuracy, and improving the accuracy of the bonding strength between the tube core 10 and the wafer 20. And the test method provided by the present application can be applied to different integrated structures 100 formed by various bonding methods, the process is simple, and the scope of application is expanded.

[0131] Furthermore, due to the large size difference between the die 10 and the wafer 20, after the above test method is executed, most of the area on the wafer 20 (except the area bonded to the die 10) can still be used for the preparation of semiconductor products, which is beneficial to cost saving.

[0132] In some embodiments, Fig.10 As shown, the present application also provides a bonding strength testing device 1000. The bonding strength testing device 1000 includes: a testing platform 1100, a processing control unit 1200 and a display unit 1300.

[0133] The test platform 1100 is used to fix the integrated structure 100 formed by bonding the wafer 20 and the die 10 (see Figure 5 (a) in the figure.

[0134] The processing control unit 1200 is used to obtain edge M information of the bonding interface between the die 10 and the wafer 20, and form a groove structure 21 along the edge M of the bonding interface. Also, the die 10 is pulled by the fixture 200, and the pulling force value information is recorded; and the bonding strength between the die 10 and the wafer 20 is determined based on the pulling force value.

[0135] The display unit 1300 is coupled to the processing control unit 1200 and is used to display the tension value information and the bonding strength information.

[0136] For example, the processing control unit 1200 may include: an image collector, an etching component, a tension sensor, and a controller.

[0137] The image collector is used to obtain edge M information of the bonding interface between the tube core 10 and the wafer 20. The image collector includes an optical lens. The etching component is coupled to the image collector and is used to form a groove structure 21 along the edge M of the bonding interface. The tension sensor is used to pull the tube core 10 through the clamp and transmit the tension value.

[0138] The controller is coupled to the image collector, the etching assembly and the tension sensor, and is used to control the image collector, the etching assembly and the tension sensor, and display the tension information, for example, displaying multiple tension values ​​in the process of pulling the tube core 10, and identifying the tension value representing the bonding strength.

[0139] In some examples, the processing control unit 1200 is further used to form a protection layer 30 on a side of the die 10 away from the wafer 20 according to position information of the die 10 , and / or rinse the integrated structure 100 after forming the groove structure 21 , and perform a drying process.

[0140] Illustratively, the process control unit 1200 includes a component for dripping the laser cutting protection liquid, and a cleaning component for flushing the integrated structure 100 .

[0141] It should be noted that the embodiments of the bonding strength testing method provided in the present application and the embodiments of the bonding strength testing device belong to the same concept; the technical features in the technical solutions recorded in the embodiments can be arbitrarily combined without conflict. However, it should be further noted that the bonding strength testing method provided in the embodiments of the present application, the combination of its various technical features can already solve the technical problem to be solved by the present application; therefore, the bonding strength testing method provided in the embodiments of the present application may not be limited by the bonding strength testing device provided in the embodiments of the present application.

[0142] The above is only a preferred embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for testing bonding strength, characterized in that: include: Providing an integrated structure formed by die and wafer bonding; determining an edge of a bonding interface between the die and the wafer; A groove structure is formed at the edge of the bonding interface on the surface of the wafer on one side close to the tube core; the edge of the tube core is located on the side of the opening of the groove structure along a direction perpendicular to the plane where the wafer is located; Pulling the tube die based on the groove structure, and determining the bonding strength between the tube die and the wafer; Wherein, forming a groove structure on the surface of the wafer on the side close to the tube core at the edge of the bonding interface comprises: irradiating the edge of the bonding interface with a laser having a pulse width less than a preset value in a direction having an angle with the plane where the wafer is located, so as to form the groove structure; the preset value is the minimum pulse width of the laser that is related to the size of the tube core or affects the performance of the tube core and the wafer; The laser irradiates the edge of the bonding interface, including: continuously scanning the edge of the bonding interface with the laser to form an annular groove surrounding the tube core; or scanning the edge of the bonding interface with the laser at intervals to form a plurality of grooves surrounding the tube core, and two of the plurality of grooves are located on a center line of the tube core; The pulling out of the tube core based on the groove structure includes: pulling out a plurality of the tube cores respectively based on the groove structure, and respectively determining the bonding strength between the plurality of the tube cores and the wafer.

2. The testing method according to claim 1, characterized in that: Pulling the tube die based on the groove structure and determining the bonding strength between the tube die and the wafer includes: The test hook extends into the groove structure and contacts with a side surface of the tube core to pull the tube core; increasing the tension applied to the tube core at intervals of a first time length, recording the tension value of the tension applied to the tube core, and drawing a tension value curve according to a plurality of the tension values; It is determined that when the tension value suddenly decreases, the maximum tension value among the multiple tension values ​​is the bonding strength.

3. The testing method according to claim 1, characterized in that: Pulling the tube die based on the groove structure and determining the bonding strength between the tube die and the wafer includes: The test hook extends into the groove structure and contacts with a side surface of the tube core to pull the tube core; Recording the tensile force value of the tube die at every second time interval, and acquiring image information of the bonding interface between the tube die and the wafer at every second time interval; The pulling force value when the tube die is separated from the wafer is determined as the bonding strength.

4. The testing method according to claim 1, characterized in that: The integrated structure includes a plurality of the dies distributed in different areas of the wafer; The method comprises: irradiating the edges of the bonding interfaces between the dies and the wafer with a laser to form a plurality of the groove structures; The bonding strength between the tube die and the wafer is determined according to an average value of the bonding strength between a plurality of the tube dies and the wafer.

5. The testing method according to claim 1, characterized in that: Determining the edge of the die and the wafer bonding interface includes: Using an optical lens to obtain the edge of the bonding interface between the die and the wafer; and / or, Acquire alignment parameters during the bonding process of the tube die and the wafer, and determine the edge of the bonding interface between the tube die and the wafer according to the structure of the tube die.

6. The testing method according to claim 1 or 5, characterized in that: The method further comprises: Based on the position information of the tube die, a protective layer is formed on a side of the tube die away from the wafer; the protective layer at least covers an edge region of a bonding interface between the tube die and the wafer.

7. The testing method according to claim 6, characterized in that: The step of forming a protective layer on a side of the die away from the wafer comprises: Determining the position and size of the die; A laser cutting protection liquid is used to form the protection layer on the surface of the tube core away from the wafer; one protection layer is used to cover one tube core.

8. The testing method according to claim 6, characterized in that: After forming the groove structure, the method further includes: removing the protective layer; and / or, The groove structure is rinsed to remove the residue in the groove structure.

9. The testing method according to claim 1, characterized in that: The integrated structure formed by bonding the die and the wafer comprises: providing the hybrid bonded die and wafer; And / or, providing the die and the wafer bonded without forming interconnect wires between the die and the wafer.

10. A device for testing bonding strength, characterized in that: include: A test base, used to fix the integrated structure formed by bonding the wafer and the die; A processing control unit, used to obtain edge information of the bonding interface between the tube core and the wafer, form a groove structure along the edge of the bonding interface, and pull the tube core through a clamp and record the pulling force value information; determine the bonding strength between the tube core and the wafer based on the pulling force value; wherein the processing control unit is used to set the pulse width of the laser to be less than a preset value, and adjust the irradiation direction of the laser so that the laser irradiates the edge of the bonding interface along a direction having an angle with the plane where the wafer is located to form the groove structure; the groove structure includes an annular groove surrounding the tube core, or a plurality of grooves surrounding the tube core, and two of the plurality of grooves are located on a center line of the tube core; the preset value is the minimum pulse width of the laser that is related to the size of the tube core or affects the performance of the tube core and the wafer; and the processing control unit is also used to pull a plurality of the tube cores respectively, and record the pulling force value information of different tube cores, and determine the bonding strength between the plurality of the tube cores and the wafer respectively; The display unit is coupled to the processing control unit and is used to display the tension value information and the bonding strength information.

11. The device according to claim 10, characterized in that The processing control unit is also used to form a protective layer on the side of the tube die away from the wafer according to the position information of the tube die, and / or to rinse the integrated structure after forming the groove structure and perform a drying process.

Images