An apparatus and method for confirming a crack position of a bonded wafer

Abstract

The application provides a device and method for confirming the crack position of a bonded wafer, wherein the device comprises a bonded wafer placing part, a light source, an image sensing part, a plug part and a light shielding part; the plug part is arranged outside the bonded wafer placing part, and a plug is inserted into the bonded wafer for confirming the crack position; and the bonded wafer placing part, the light source, the image sensing part and the plug part are covered in the light shielding part. The image sensing technology can be used to observe the wafer position in real time, the wafer defects can be observed conveniently, and the wafer crack position can be positioned accurately. The plug part is inserted into the wafer crack position, the wafer crack source can be found more accurately, and then the personnel can be assisted to improve the process; the bonded wafer crack position can be positioned accurately by using a simple structure, the wafer detection efficiency is improved, and the false detection and the missed detection caused by manual detection are reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of semiconductor manufacturing, and particularly relates to a device and method for confirming the crack position of a bonded wafer. BACKGROUND

[0002] Lithium niobate material is a functional crystal material with excellent piezoelectric, electro-optic and nonlinear optical properties, and plays an important role in the fields of optoelectronics, radio frequency communication and sensing. In recent years, with the development of heterogeneous integration technology, lithium niobate bonded wafer has become one of the core directions of the new generation of photonic integration platform. Lithium niobate bonded wafer combines single-crystal lithium niobate thin film and silicon, silicon nitride (SiN) or silicon-on-insulator (SOI) substrate through advanced wafer bonding technology (such as direct bonding, medium layer assisted bonding, etc.), forming a heterogeneous structure. Through nanoscale thin film preparation and micro-nano processing technology, low-loss optical waveguide, high-speed electro-optic modulator and high-efficiency nonlinear optical devices can be realized, which significantly improves the bandwidth and energy efficiency of optical communication systems. In recent years, with the gradual improvement of lithium niobate bonding technology, lithium niobate bonded wafer has shown great potential in the fields of 5G / 6G radio frequency front-end, quantum optics and microwave photonics, and has developed rapidly in the fields of optoelectronic devices, all-optical signal processing, optical data storage and optical sensing.

[0003] After lithium niobate is bonded with silicon carbide wafer, the wafer is prone to cracking during the bonding annealing process due to stress and other reasons, and cracks may occur. However, since both materials are transparent materials, it is difficult to confirm the position of the cracks generated by bonding and the type of wafer on which the cracks occur, and therefore there is an urgent need for a device to detect and judge the cracks generated by the wafer.

[0004] The existing technology for detecting wafer crack defects mainly includes the following: 1. Using automatic optical detection (AOI) wafer defect technology, such as patent No. CN115753822A, wafer defect detection device, which detects by setting light source, image sensing technology, but this technology can only detect the existence of cracks in the wafer, and cannot confirm the specific position of the cracks; 2. CN119164969A, a wafer quality detection method in an ultra-clean environment, discloses the use of laser scanning, infrared thermal imager, ultrasonic detection and other technologies, which is too fine in practical application and has low detection efficiency for bonded wafers; 3. CN118533860A discloses a wafer crack detection device and method, which can accurately detect whether the wafer has cracks by outputting information using photosensitive sensing technology. This technology is only suitable for single wafers, and cannot confirm the position of the cracks for bonded substrates. SUMMARY

[0005] In order to solve the above problems, the application provides a device for confirming the crack position of a bonded wafer, comprising: a bonded wafer placing part, a light source, an image sensing part, a plug part, and a light shielding part; the light source is arranged above the bonded wafer placing part; the image sensing part is arranged above the bonded wafer placing part and transmits images to a display device; the plug part is arranged outside the bonded wafer placing part, and a plug is inserted into the bonded wafer for confirming the crack position; and the bonded wafer placing part, the light source, the image sensing part, and the plug part are covered in the light shielding part.

[0006] Further, the plug part comprises a plug clamping part, the plug clamping part is a jaw structure, the contact surface of the jaw structure and the plug is provided with an anti-skid structure, the anti-skid structure is an array of hemispherical protrusions, the diameter of the hemispherical protrusions is 0.5-1mm, and the distance between adjacent hemispherical protrusions is 1-2mm.

[0007] Further, the hemispherical protrusions are polyurethane materials with a Shore hardness of 30-50A.

[0008] Further, the material of the plug is one or more composite materials selected from tungsten carbide, polycrystalline diamond, cubic boron nitride, zirconium oxide, and aluminum oxide.

[0009] Preferably, the selection of the plug material should consider multiple factors, including hardness, rigidity, chemical inertness, processability, cost, etc. The hardness of the plug should be much higher than that of the wafer to ensure that no self-wear occurs during insertion, to avoid contaminating the wafer and to ensure that the plug can accurately wedge into the wafer bonding interface. The plug needs to have high rigidity to ensure that it does not bend, deform, or shake during insertion, thereby avoiding problems such as inaccurate positioning, scratching the wafer during insertion, or causing crack propagation that affects the observation of the target crack. The plug has good chemical stability and does not react with the wafer or oxidize and shed particles when exposed to air. The plug material needs to be able to be processed into an ultra-thin, ultra-flat, and sharp-edged blade form. In addition, the plug is inserted into the wafer bonding site to serve as a background plate for crack observation, so the plug should be opaque and colored.

[0010] Preferably, the plug is smooth near the insertion end and has a mirror surface, and the contact surface of the jaw structure has a certain roughness (maintains the rough surface state after grinding without polishing treatment) and has a strong mechanical interlocking effect with the polyurethane hemispherical protrusions, achieving excellent anti-skid effect.

[0011] Further, the plug part further comprises a vertical drive assembly for lifting the plug clamping part and a horizontal drive assembly for horizontal linear reciprocating motion of the plug clamping part; the stroke of the vertical drive assembly is 50-150mm; and the horizontal drive assembly is driven by a linear motor with a stroke of 10-30μm.

[0012] Further, the horizontal driving assembly feeds back position information in real time through a motor encoder to realize accurate adjustment of the horizontal position of the blade.

[0013] Further, the insert piece part can be provided with a pressure sensor with a measurement range of 0-5N and a tension sensor provided on the lifting part with a measurement range of 0-10N, to monitor the contact force in the insertion process of the insert piece, the clamping force of the insert piece clamping part and the position coordinates of the insert piece in real time, and transmit the data to the control system; when the clamping force is detected to be lower than 0.5N or the contact force is detected to be higher than 3N, the system automatically triggers an alarm and stops the operation, to ensure that the optimal clamping state and insertion safety are maintained at all times during the transportation and insertion process. Further, the insertion end of the insert piece has a wedge-shaped cutting edge with an included angle of 5°-20° and a cutting edge thickness of 10-20μm.

[0014] The main body thickness of the insert piece is 60μm-200μm; the length of the insert piece is 10mm-30mm; and the width of the insert piece is 10mm-20mm.

[0015] Preferably, the cutting edge of the insert piece must be free of burrs and micro-cracks to avoid misjudgment of cracks or secondary damage to the wafer caused by defects in the cutting edge during insertion.

[0016] Further, the bonded wafer placement part includes a vacuum suction platform, a horizontal rotation device for continuous rotation of the vacuum suction platform in the horizontal direction by 360°, and a pitch adjustment device for realizing rotation of the vacuum suction platform in the vertical direction by -90° to +90°.

[0017] Further, the pitch adjustment device is arranged below the vacuum suction platform, and the pitch adjustment device includes a connected rotation shaft and a rotating frame, with the upper end of the rotating frame connected to the vacuum suction platform.

[0018] Further, a vacuum generator is arranged at the lower end of the rotating frame, and a channel is arranged inside the rotating frame, with one end of the channel connected to the vacuum generator and the other end of the channel connected to the vacuum suction platform.

[0019] Further, the rotating shaft is arranged on a support frame, the rotating frame is located inside the support frame, the lower end of the support frame is connected to a support frame, and the horizontal rotation device is arranged below the support frame to drive the support frame to perform horizontal rotation.

[0020] The application also provides a method for confirming the crack position of a bonded wafer, including the following steps:

[0021] (1) Place the bonded wafer on the bonded wafer placement part and fix it;

[0022] (2) Find the crack position through the image sensing part;

[0023] (3) Insert the insert piece into the middle of the wafer bonding surface. If the crack is above the insert piece, the crack is generated on the upper surface of the bonded wafer, otherwise the crack is generated on the lower surface of the bonded wafer.

[0024] The present application can bring the following beneficial effects:

[0025] 1. The present application can observe the wafer position in real time through image sensing technology, facilitate the observation of wafer defects, and accurately determine the wafer crack generation position. Then, the insert piece part is inserted into the wafer crack generation position, and the wafer crack generation source is found more accurately, so as to assist personnel to improve the process; the wafer crack generation position can be accurately positioned by using a simple structure, the wafer detection efficiency is improved, and the false detection and missed detection phenomenon caused by manual detection is reduced.

[0026] 2. The present application sets the clamping jaw structure to clamp the insert piece, and the anti-slip structure is arranged on the contact surface of the insert piece, which can increase the friction with the insert piece to prevent displacement of the insert piece, and can also avoid scratching the surface of the insert piece during clamping.

[0027] 3. The present application optimizes the material of the insert piece by comprehensively considering multiple factors (hardness, rigidity, chemical inertness, processability, cost, observability, etc.), which is beneficial to the insertion of the insert piece and the observation of the crack after insertion.

[0028] 4. The vertical driving assembly is arranged on the insert piece part to adjust the height of the insert piece to align with the wafer bonding interface, the horizontal driving assembly is arranged to adjust the horizontal distance between the insert piece and the wafer, control the insertion depth, and facilitate the observation of the direction and expansion path of the crack.

[0029] 5. The wedge-shaped blade edge design of the insert piece can gradually and smoothly enter the bonding interface, avoid accidental cracking of the wafer due to sudden stress concentration, and more effectively and controllably separate the two wafers in a local micro area. Compared with the flat blade, the initial contact of the wedge-shaped blade with the wafer is a point or a very short line, the pressure is larger, the insertion is easier, but the total force is smaller and more delicate.

[0030] 6. The design of the blade angle ensures the accuracy and low stress of insertion; the smaller the extrusion and destructiveness during insertion, the greater the integrity of the sample is maintained.

[0031] 7. The design of various parameters of the insert piece, such as the material, main body thickness, length, width, blade angle, shape, and blade thickness of the insert piece, not only controls the insertion process and minimizes the impact on the wafer after insertion, but also considers that the crack generated after insertion is minimal, the crack shape generated by the insert piece is significantly different from the target crack morphology, and thus it can be easily distinguished during subsequent observation, and thus it will not interfere with the target crack.

[0032] 8. The wafer bonding placement part of the present application is provided with a horizontal rotation device and a pitch adjustment device to realize the purpose of observing the crack state from multiple angles. BRIEF DESCRIPTION OF DRAWINGS

[0033] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their description serve to explain the present application. They do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 A structural schematic diagram of the device for identifying the crack position of the wafer in the present application;

[0035] Figure 2 A schematic diagram of the insertion of the plug into the wafer to identify the crack position;

[0036] Figure 3 Another structural schematic diagram of the device for identifying the crack position of the wafer in the present application;

[0037] Figure 4 A structural schematic diagram of the wafer placement part in the present application.

[0038] Wherein:

[0039] 1. Light source, 100. Wafer, 2. Wafer placement part, 21. Vacuum suction platform, 22. Horizontal rotation device, 23. Rotation shaft, 24. Rotation frame, 25. Vacuum generator, 251. Channel, 26. Bracket, 27. Support frame, 3. Plug part, 31. Plug, 32. Plug clamping part, 33. Anti-slip structure, 34. Vertical drive assembly, 35. Horizontal drive assembly, 4. Light shielding part, 5. Image sensing part, 6. Display device. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the overall concept of the present application, the following will be described in detail in an exemplary manner with reference to the drawings.

[0041] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0042] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0045] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0046] In one embodiment, an apparatus for identifying the location of a bonding wafer crack is provided, as shown in the attached diagram. Figure 1 Appendix Figure 2As shown, the device structure includes: a bonded wafer placement part 2, a light source 1, an image sensing part 5, a plug part 3, and a light shielding part 4. The light source 1 is arranged above the bonded wafer placement part 2, and the image sensing part 5 is arranged above the bonded wafer placement part 2 to transmit images to a display device 6. The plug part 3 is arranged outside the bonded wafer placement part 2, and a plug 31 is inserted into the bonded wafer 100 to confirm the crack position. The bonded wafer placement part 2, the light source 1, the image sensing part 5, and the plug part 3 are all covered in the light shielding part 4.

[0047] In actual use, first, place the bonded wafer 100 to be tested with the front face upward on the bonded wafer placement part 2, then turn on the detection light source 1, rotate the bonded wafer placement part 2, and observe the crack condition of the wafer on the display device 6 through the image sensing part 5. After the wafer crack is found, take a photo and record the position. Adjust the wafer crack position to the plug part 3, then adjust the position of the plug 31 up and down, insert the plug 31 at the crack position, and insert the plug 31 between the bonding surfaces of the two wafers. Observe the crack image. If the plug 31 insertion position shows a crack image, it proves that the crack grows on the front face of the wafer, otherwise it grows on the back face of the wafer.

[0048] In another embodiment, the plug part 3 is further structurally designed, as shown in Figure 3 The plug part 3 includes a plug clamping part 32, the contact surface of the clamping jaw structure and the plug 31 is provided with an anti-skid structure 33, the anti-skid structure 33 is an array of hemispherical protrusions, the diameter of the hemispherical protrusions is 0.5-1mm, and the distance between adjacent hemispherical protrusions is 1-2mm. The hemispherical protrusions are polyurethane materials with a Shore hardness of 30-50A. The material of the plug 31 is one or more composite materials of tungsten carbide, polycrystalline diamond, cubic boron nitride, zirconia, and alumina.

[0049] In another embodiment, as shown in Figure 3 The plug part 3 further includes a vertical driving assembly 34 and a horizontal driving assembly 35. The stroke of the vertical driving assembly 34 is 50-150mm. The vertical driving assembly 34 is arranged below the plug clamping part 32 to adjust the height of the plug clamping part 32. The specific driving structure can adopt conventional lifting mechanisms, such as linear motor driving, telescopic air cylinder, etc.

[0050] The horizontal driving assembly 35 can be arranged above the vertical driving assembly 34 to drive the telescopic movement of the plug clamping part by using telescopic structures such as air cylinders and linear motors. The vertical driving assembly drives the lifting movement of the overall structure above.

[0051] As shown in Figure 3As shown, the horizontal driving assembly 35 can be arranged outside the vertical driving assembly to drive the whole of the insert piece part 3 to make horizontal reciprocating motion, and the lower end of the insert piece part 3 can be provided with a slide structure. The horizontal driving assembly 35 is driven by a linear motor, and the stroke is 10-30 μm.

[0052] In another embodiment, the insert piece 31 is further structurally designed, the insertion end of the insert piece 31 has a wedge-shaped blade edge with an included angle of 5°-20° and a blade edge thickness of 10-20 μm; the main body thickness of the insert piece 31 is 60 μm-200 μm; the length of the insert piece 31 is 10 mm-30 mm; and the width of the insert piece 31 is 10 mm-20 mm.

[0053] In actual application, the bonded wafer 100 formed after the lithium niobate and silicon carbide wafer bonding is inserted with the insert piece 31, the insert piece 31 is inserted into the middle of the bonding surface of the two wafers, and the crack image is observed. The crack generated by the insertion of the insert piece 31 of the present application is not the same as the crack (target crack) caused by thermal stress. The crack generated after the bonding and annealing of silicon carbide and lithium niobate is a straight crack penetrating the wafer surface. The crack generated by the insertion of the insert piece 31 of the present application is a small curved crack, and the two crack morphologies can be easily distinguished by the naked eye.

[0054] In another embodiment, the bonded wafer placement part 2 is further structurally designed, as shown in Figure 4 The bonded wafer placement part 2 includes a vacuum adsorption platform 21, a horizontal rotation device 22 for continuous rotation of the vacuum adsorption platform 21 in the horizontal direction 360°, and a pitch adjustment device for realizing -90° to +90° rotation of the vacuum adsorption platform 21 in the vertical direction. The pitch adjustment device is arranged below the vacuum adsorption platform 21, and includes a connected rotation shaft 23 and a rotating frame 24, and the upper end of the rotating frame 24 is connected with the vacuum adsorption platform 21. A vacuum generator 25 is arranged at the lower end of the rotating frame 24, and a channel 251 is arranged inside the rotating frame 24, one end of the channel 251 is connected with the vacuum generator 25, and the other end of the channel 251 is connected with the vacuum adsorption platform 21. The rotating shaft 23 is arranged on a support 26, the rotating frame 24 is located inside the support 26, the lower end of the support 26 is connected with a support frame 27, and the horizontal rotation device 22 is arranged below the support frame 27 to drive the support frame 27 to make horizontal rotation motion.

[0055] The bonding wafer placing part 2, in use, places the bonding wafer 100 on the vacuum adsorption platform 21, and due to the structure of the vacuum generator 25 and the channel 251, the bonding wafer 100 is adsorbed and fixed on the platform; if the position of the wafer needs to be adjusted during the observation of wafer cracks, the horizontal rotating device 22 can be used to drive the support frame 27 to make horizontal rotating movement, thereby driving the support frame 26 and the vacuum adsorption platform 21 to make horizontal rotating movement. If the vacuum adsorption platform 21 needs to be adjusted in the vertical direction to change the inclination angle, the rotating shaft 23 is rotated forward or reversely, thereby driving the vacuum adsorption platform 21 on the rotating frame 24 to make the movement of bending or lifting, so as to change the inclination angle. The outer end of the rotating shaft 23 can be connected with a motor, and the rotating direction and angle of the rotating shaft 23 are controlled by the motor.

[0056] Each of the embodiments in the specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the difference from other embodiments. Especially, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts can be referred to the part of the method embodiment.

[0057] The above only describes the embodiments of the present application and is not used to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. An apparatus for confirming the location of cracks in bonded wafers, characterized in that, It comprises: a bonded wafer placing part, a light source arranged above the bonded wafer placing part, an image sensing part arranged above the bonded wafer placing part to transmit images to a display device; a tab part arranged outside the bonded wafer placing part, and a tab is inserted into the middle of the wafer bonding surface to confirm the crack position generated on the upper surface or lower surface of the bonded wafer; a light shielding part covering the bonded wafer placing part, the light source, the image sensing part, and the tab part in the light shielding part.

2. The apparatus for confirming the position of a crack in a bonded wafer according to claim 1, wherein: The tab part comprises a tab clamping part in a jaw structure, and the contact surface of the tab clamping part is provided with an anti-skid structure in the form of an array of hemispherical protrusions, the diameter of the hemispherical protrusions is 0.5-1mm, and the distance between adjacent hemispherical protrusions is 1-2mm. The hemispherical protrusions are made of polyurethane material with a Shore hardness of 30-50A.

3. The apparatus for confirming the position of a crack in a bonded wafer of claim 1, wherein: The material of the tab is one or more composite materials selected from tungsten carbide, polycrystalline diamond, cubic boron nitride, zirconia, and alumina.

4. The apparatus for confirming the position of a crack in a bonded wafer of claim 2, wherein: The tab part further comprises a vertical driving assembly for lifting the tab clamping part and a horizontal driving assembly for horizontal linear reciprocating motion of the tab clamping part; the stroke of the vertical driving assembly is 50-150mm; and the stroke of the horizontal driving assembly is 10-30μm.

5. The apparatus for confirming the position of a crack in a bonded wafer of claim 1, wherein: The insertion end of the tab is provided with a wedge-shaped cutting edge with an included angle of 5°-20° and a thickness of 10-20μm. The main body of the tab has a thickness of 60-200μm, a length of 10-30mm, and a width of 10-20mm.

6. The apparatus for confirming a crack position of a bonded wafer according to claim 1, wherein: The bonded wafer placing part comprises a vacuum suction platform, a horizontal rotation device for continuous rotation of the vacuum suction platform in the horizontal direction by 360°, and a pitch adjustment device for rotation of the vacuum suction platform in the vertical direction by -90° to +90°.

7. The apparatus for confirming the position of a crack in a bonded wafer of claim 6, wherein: The pitch adjustment device is arranged below the vacuum suction platform and comprises a rotating shaft and a rotating frame connected thereto, and the upper end of the rotating frame is connected to the vacuum suction platform.

8. The apparatus for confirming the position of a crack in a bonded wafer of claim 7, wherein: A vacuum generator is arranged at the lower end of the rotating frame, and a channel is arranged inside the rotating frame, one end of the channel is connected to the vacuum generator, and the other end of the channel is connected to the vacuum suction platform.

9. The apparatus for confirming the position of a crack in a bonded wafer of claim 7, wherein: The rotating shaft is arranged on a support, the rotating frame is located inside the support, the lower end of the support is connected to a support frame, and the horizontal rotation device is arranged below the support frame to drive the support frame to rotate horizontally.

10. A method for confirming the location of a bonded wafer crack, characterized in that, The method comprises the following steps: (1) placing the bonded wafer on the bonded wafer placing part and fixing it; (2) finding the crack position through the image sensing part; (3) inserting the tab into the middle of the wafer bonding surface, and if the crack is above the tab, the crack is generated on the upper surface of the bonded wafer, otherwise the crack is generated on the lower surface of the bonded wafer.

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