Wafer bonding slide three-dimensional scanning detection device and method

Abstract

The application discloses a wafer bonding slip three-dimensional scanning detection device and method, the device comprises a wafer stage, a rotary drive mechanism, a detection module and a control processing unit. The method is relative rotation to the wafer through the detection module, full three-dimensional scanning of the wafer edge is carried out, the three-dimensional appearance of the wafer edge is restored, the radial distance of the upper and lower wafer edges at each angle is measured, and if the radial distance exceeds the slip threshold, the slip is determined. Through statistical analysis of the radial distance data of the same batch of wafers, the systematic offset trend of the machine system is identified, and the compensation value is calculated, and the bonder is automatically adjusted. The application can realize high-precision detection of micron-level to nanometer-level slip, can identify the systematic offset of the machine system to realize automatic compensation, and is suitable for online full detection of mass production lines.

Description

Technical Field

[0001] This invention relates to the field of inspection technology in wafer-level bonding processes, and particularly to a three-dimensional scanning inspection device and method for wafer bonding sliders. Background Technology

[0002] Direct wafer bonding involves pre-bonding two cleaned and surface-activated wafers at room temperature using van der Waals forces or hydrogen bonds, followed by high-temperature annealing to form a stable chemical bond. Direct wafer bonding is one of the most researched bonding methods in recent years, but it is also the most challenging, demanding the highest standards for silicon wafer surface morphology and surface treatment processes, thus often resulting in bonding failures.

[0003] Because wafer materials are expensive, every step of the process must ensure material safety to avoid wafer damage or scrap due to operational errors. When bonding fails, it usually results in the scrapping of two wafers, making the cost of bonding failure extremely high. Bonding failures may be caused by problems with the bonding machine or poor silicon wafer surface topography, but if the bonding machine can detect bonding failures in time and stop operation immediately, the losses can be prevented from escalating.

[0004] To promptly detect the success of bonding, it is necessary to inspect the wafer edges or alignment marks after bonding to determine if there has been relative displacement between the two wafers, resulting in wafer slippage. Wafer slippage refers to the phenomenon where, after wafer bonding, there is relative displacement between the upper and lower wafers, which may prevent subsequent processes from being completed.

[0005] Currently, there are two main methods for detecting wafer slip after the wafer bonding process:

[0006] The first method is the diameter measurement method. See Figure 1 As shown, this is an existing vision-based inspection system that uses a vision inspection lens 13 to identify the edges or alignment marks of the wafer pair 10 to determine whether there is relative displacement between the first wafer 11 and the second wafer 12 bonded vertically, indicating slippage. This method uses an infrared camera as the vision inspection lens 13 to capture a top-down view of the wafer pair 10 from directly above. Image processing algorithms are used to extract the edge contours of the wafer pair and measure their diameters. The measurement results are compared with a standard diameter; if the deviation exceeds a preset threshold, slippage is determined.

[0007] The second method is the double black line spacing measurement method. This method uses a common light source to illuminate the bonding wafer pair vertically from above. When the upper and lower wafers slip relative to each other, due to edge misalignment, two clear black lines will form in the wafer edge region, corresponding to the actual edge positions of the upper and lower wafers, respectively. By measuring the pixel distance between the two black lines and combining it with the pixel equivalent calibrated by the system, the actual slippage amount can be calculated. If the slippage amount exceeds the threshold allowed by the process, it is determined to be slippage.

[0008] The above-mentioned detection technologies have the following shortcomings:

[0009] First, the detection accuracy is low. In practical applications on mass production lines, traditional sliding wafer detection methods are limited by factors such as camera resolution, full-field imaging requirements, and wafer surface reflection interference. Their reliable detection accuracy is typically on the order of 50-70μm, which cannot meet the needs of advanced packaging for micron-level sliding wafer detection.

[0010] Secondly, it has poor anti-interference ability. After bonding, the wafer is polished on both sides, which easily produces specular reflection, resulting in image overexposure and edge extraction failure.

[0011] Finally, the cost is high. Traditional sliding plate testing has low accuracy and cannot meet the requirements for micron-level detection; therefore, specialized metrology equipment is needed in actual production. However, such specialized equipment is very expensive, costing millions of yuan, which is unaffordable for small and medium-sized enterprises.

[0012] Based on the above, and in view of the problems existing in the prior art, the present invention proposes the following technical solutions. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to overcome the problems existing in the prior art and provide a three-dimensional scanning detection device and method for wafer bonding sliders.

[0014] To address the aforementioned technical problems, this invention provides a three-dimensional scanning inspection device for wafer bonding sliding. This inspection device is used to detect whether a first wafer and a second wafer in a bonded wafer pair have a relative offset. The device includes: a stage for supporting the bonded wafer pair, a detection module for acquiring morphological data of the wafer pair edges, and a rotation drive mechanism. The stage or the detection module achieves relative rotational movement through the rotation drive mechanism. The detection module acquires morphological data of the wafer pair edges while rotating relative to the edge of the stage.

[0015] Furthermore, in the above-mentioned detection device, the detection module is connected to the lower end of a telescopic arm. The telescopic arm moves vertically, causing the detection module to run between the upper retracted position and the lower scanning position, and the scanning position is located at the periphery of the wafer.

[0016] Furthermore, in the technical solution of the above-mentioned detection device, the rotary drive mechanism can be implemented in the following two ways: Method 1: The rotary drive mechanism is positioned above the stage, and the telescopic arm is connected to the output end of the rotary drive mechanism. The rotary drive mechanism drives the telescopic arm and the detection module to move in a circular motion around the edge of the wafer. Method 2: The rotary drive mechanism is connected to the stage to drive the stage to rotate around its central axis.

[0017] This invention also provides a three-dimensional scanning detection method for wafer bonding slip, the method comprising the following steps: Step 1: Calibrate the detection device and obtain the system resolution R, wherein the system resolution represents the minimum displacement that the detection device can reliably resolve; Step 2: Full-circumference three-dimensional scanning, placing the bonding wafer pair to be tested on the stage, and using a rotation drive mechanism to generate a 360° relative rotation between the detection module and the wafer pair, continuously acquiring the morphological data of the wafer pair edges during the relative motion to obtain raw data covering the entire circumference of the wafer pair; Step 3: Processing the acquired data to reconstruct the complete three-dimensional morphology of the wafer pair edges; Step 4: Radial distance measurement and slip determination, extracting the radial positions of the upper and lower wafer edges at various angles from the reconstructed three-dimensional morphology, and measuring the radial distance D of the upper and lower wafer edges at various angles; if any angle θ exists such that D exceeds a preset slip threshold T, the wafer is determined to have a slip defect; otherwise, it is determined to be qualified; wherein, the slip threshold T is not less than the system resolution R.

[0018] Furthermore, in the above-mentioned detection method, the detection method also includes: Step 5: Machine stability analysis and automatic compensation, statistical analysis of the D data of the same batch of wafers, calculation of the average radial distance at each angle, identification of the systematic offset trend of the machine based on the distribution law of radial distance with angle, calculation of compensation value and sending it to the bonding machine for adjustment.

[0019] Furthermore, in the technical solution of the above detection method, in step 1, the system resolution R is obtained by the following method: selecting a standard calibration piece of known size for repeated measurements, calculating the standard deviation σ of the measured values, and setting the system resolution R = kσ, where k is the confidence coefficient.

[0020] Furthermore, in the technical solution of the above detection method, the sliding plate threshold T in step 4 is set according to the maximum allowable offset of the process.

[0021] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages:

[0022] 1. This invention uses three-dimensional scanning technology to restore the edge morphology of the wafer and directly measure the radial distance between the upper and lower wafer edges. The system resolution comprehensively reflects the detection capabilities of each core component of the device. Core components can be selected according to actual needs to achieve micron-level to nanometer-level precision detection.

[0023] 2. Strong anti-interference capability. Compared to traditional infrared imaging methods that rely on wafer surface reflection, where double-sided polishing after bonding creates a mirror-like surface, light is repeatedly reflected and struggles to enter the camera, leading to overexposure or bright spots and edge extraction failure. Furthermore, changes in ambient light and surface contamination can severely impact the stability of the detection results. This invention employs active measurement technology, acquiring wafer edge morphology information from multiple angles to ensure effective signal reception and effectively solve the measurement blind zone problem caused by unidirectional imaging. This technology does not rely on the reflective properties of the wafer surface, enabling stable imaging even on highly reflective double-sided polished wafers. Simultaneously, the active light source is unaffected by changes in ambient light, ensuring the stability and reliability of the detection results.

[0024] 3. This invention identifies whether there is a systematic offset in the machine by statistically analyzing the radial distance distribution trend of the same batch of wafers, using the difference in radial distance between 0° and 180° to identify the X-direction offset, and using the difference in radial distance between 90° and 270° to identify the Y-direction offset.

[0025] 4. The detection device of the present invention provides two different application modes. When using it, the appropriate mode can be flexibly selected according to different application scenarios and spatial layouts, thereby improving the applicability of the present invention. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an existing detection method;

[0027] Figure 2 This is a schematic diagram of the structure of the detection device of the present invention in Embodiment 1;

[0028] Figure 3 This is a schematic diagram of the structure of the detection device of the present invention under another state in Embodiment 1;

[0029] Figure 4 This is a schematic diagram illustrating the working principle of the detection device of the present invention in Embodiment 1;

[0030] Figure 5 This is a schematic diagram of the structure of the detection device of the present invention in Embodiment 2;

[0031] Figure 6 This is a schematic diagram of the 3D model of the morphology obtained for this invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] See Figures 2 to 4 As shown, this is Embodiment 1 of the present invention. Embodiment 1 provides a wafer bonding slider three-dimensional scanning inspection device for detecting whether the first wafer 11 and the second wafer 12 in the bonded wafer pair 10 have a relative offset. The inspection device includes: a stage 2, an inspection module 3, and a rotation drive mechanism 4.

[0034] The stage 2 is used to support the bonded wafer pair 10 and can support wafers of different sizes. Typically, the stage 2 has a vacuum adsorption function to adsorb and fix the wafers placed on it.

[0035] The detection module 3 is used to collect the topographic data of the wafer's 10 edges. In this embodiment, the detection module 3 can be an active measurement instrument such as a laser displacement sensor or a line laser profilometer.

[0036] The rotation drive mechanism 4 is used to drive the stage 2 or the detection module 3 to achieve relative rotational motion, and then the detection module 3 is used to collect the morphology data of the wafer pair 10 edge along the edge of the stage 2.

[0037] In this first embodiment, the rotary drive mechanism 4 is positioned above the stage 2, and the detection module 3 is connected to the rotation output end of the stage 2 via a telescopic arm 31. Specifically, the detection module 3 is connected to the lower end of the telescopic arm 31. This telescopic arm 31 can move vertically, thereby driving the detection module 3 to operate between the upper retracted position and the lower scanning position.

[0038] The retracted position refers to the position where the telescopic arm 31 is retracted to its shortest length. At this time, the telescopic arm 31 will approach the upper rotary drive mechanism 4, so that the telescopic arm 31 will not interfere with the space between the rotary drive mechanism 4 and the stage 2, which facilitates the operation of devices such as robotic arms for picking up and placing wafers.

[0039] The scanning position is located around the wafer pair 10 so that the detection module 3 can collect the morphology data of the edge of the wafer pair 10.

[0040] The rotary drive mechanism 4 is used to drive the detection module 3 to perform circular motion, and its specific structure can be set according to actual needs. For example, a gear transmission mechanism can be used, which is driven by a motor to drive the telescopic arm 31 to perform circular motion.

[0041] The detection method of the present invention will be described below with reference to the above embodiments.

[0042] The detection method includes the following steps:

[0043] Step 1: Calibrate the detection device and obtain the system resolution R, which represents the minimum displacement that the detection device can reliably distinguish.

[0044] Before using the detection device of this invention for formal testing, the device needs to be calibrated. The typical method is to select a standard calibration piece of known size and perform multiple repeated measurements, calculate the standard deviation σ of the measured values, and set the system resolution R = kσ, where k is the confidence coefficient (usually 3 or 6). The system resolution comprehensively reflects the combined influence of factors such as light source fluctuations, optical system aberrations, sensor noise, and mechanical vibration on the detection capability, representing the minimum displacement that the device can reliably resolve.

[0045] Simultaneously, the sliding threshold T is set according to process requirements. The sliding threshold T is the maximum allowable offset of the process. For example, for a specific process, the allowable sliding amount is no more than 5μm, so T=5μm is set. The system resolution R must be less than or equal to T to ensure that the device can reliably detect sliding defects that exceed the allowable range of the process.

[0046] Step 2: After calibrating the testing device, testing can begin. First, place the bonded wafer pair 10 to be tested on the stage 2. The stage 2 fixes the wafer pair 10 by means of vacuum adsorption or other methods.

[0047] Then, the detection module 3 is driven to rotate around the periphery of the wafer pair 10 by the rotation drive mechanism 3, so that the two rotate relative to each other. During the relative motion, the detection module 3 continuously collects the morphology data of the edge of the wafer pair 10 to obtain the raw data covering the entire circumference of the wafer pair 10.

[0048] Step 3: Process the acquired raw data, including filtering and noise reduction, data stitching, coordinate transformation, etc., to restore the complete three-dimensional morphology of the wafer edge. For example... Figure 6 As shown, this is the restored three-dimensional topography image 100, which restores the upper wafer edge 110 and the lower wafer edge 120 (the middle area is not scanned, so it is blank). The spatial positions of the upper wafer edge 110 and the lower wafer edge 120 can be clearly distinguished through this restored three-dimensional topography image 100.

[0049] Step 4: Radial distance measurement and slip determination. Extract the radial positions of the upper wafer 11 edge and the lower wafer 12 edge at various angles from the restored 3D morphology, and measure the radial distance D of the upper and lower wafer edges at various angles. If there is any angle θ that makes D exceed the preset slip threshold T, the wafer is determined to have a slip defect; otherwise, it is determined to be qualified.

[0050] In addition, the detection method of this invention also includes a pair of steps for machine stability analysis and automatic compensation. That is, the stability of the entire wafer bonding machine is analyzed using this busy detection device. If a systematic offset trend is found, automatic compensation is performed. That is, this invention also includes step 5: machine stability analysis and automatic compensation, which involves statistically analyzing the D data of the same batch of wafers, calculating the average radial distance at each angle, identifying the systematic offset trend of the machine based on the distribution law of radial distance with angle, calculating the compensation value, and sending it to the bonding machine for adjustment.

[0051] Step 5 involves statistically analyzing the D(θ) data of the same batch of wafers to calculate the average radial distance at each angle. According to geometric principles, when the upper wafer 11 and the lower wafer 12 undergo relative translational misalignment, their radial distance D(θ) exhibits a sinusoidal distribution with respect to angle θ. Specifically:

[0052] If the upper wafer 11 is offset by Δx relative to the lower wafer 12 in the positive X direction, then D(0°) = Δx in the 0° direction, D(180°) = Δx in the 180° direction, and D(90°) = D(270°) = 0 in the 90° and 270° directions (ideally). This indicates a systematic offset of the machine tool in the X direction (0°-180° direction), and the average compensation value ΔX in the X direction is calculated.

[0053] If the upper wafer 11 is offset by Δy in the positive Y direction relative to the lower wafer 12, then D(90°) = Δy in the 90° direction, D(270°) = Δy in the 270° direction, and D(0°) = D(180°) = 0 in the 0° and 180° directions (ideally). In this case, it indicates that the machine has a systematic offset in the Y direction (90°-270° direction). Calculate the average compensation value ΔY in the Y direction.

[0054] If there are offsets in both the X and Y directions, then the radial distance D(θ) = Δx·cosθ + Δy·sinθ.

[0055] Based on the above principles and the analysis results of the machine stability, the present invention can adjust the micro-axis of the bonding machine through the control processing unit, and compensate for the offset in the opposite direction to restore the machine to a stable state.

[0056] In actual production, when a bonding machine continuously bonds multiple wafers, systematic misalignment of the alignment system may occur due to thermal expansion or mechanical wear. The method of this invention allows for simultaneous detection of wafer slippage and analysis of the machine's stability, thereby calculating compensation values ​​and automatically sending them to the bonding machine, achieving closed-loop control.

[0057] See Figure 5 As shown, this is a second embodiment of the detection device of the present invention. The difference from the first embodiment is that in this second embodiment, the rotary drive mechanism 4 is located below the stage 2, driving the stage 2 to rotate around its central axis. The stage 2 is provided with a fixed base 5, and the detection module 3 is mounted below the fixed base 5 via a telescopic arm 31.

[0058] Example 2 differs from Example 1 only in the driving method of relative rotation; their working principles and detection methods are the same, and will not be described in detail here.

[0059] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A three-dimensional scanning detection device for wafer bonding sliding, used to detect whether a relative shift occurs between a first wafer (11) and a second wafer (12) in a bonded wafer pair (10), characterized in that, The device includes: a stage (2) for carrying the bonded wafer pair (10), a detection module (3) for collecting topographic data of the edge of the wafer pair (10), and a rotation drive mechanism (4). The stage (2) or the detection module (3) achieves relative rotational motion through the rotational drive mechanism (4). While the detection module (3) rotates relative to the edge of the stage (2), it collects the morphology data of the edge of the wafer pair (10).

2. The wafer bonding slider three-dimensional scanning inspection device according to claim 1, characterized in that, The detection module (3) is connected to the lower end of a telescopic arm (31). The telescopic arm (31) moves in the vertical direction, causing the detection module (3) to run between the upper contracted position and the lower scanning position, and the scanning position is located on the periphery of the wafer pair (10).

3. The wafer bonding slider three-dimensional scanning inspection device according to claim 2, characterized in that, The rotary drive mechanism (4) is located above the stage (2), and the telescopic arm (31) is connected to the output end of the rotary drive mechanism (4). The rotary drive mechanism (4) drives the telescopic arm (31) and the detection module (3) to make circular motion around the edge of the wafer pair (10).

4. The wafer bonding slider three-dimensional scanning inspection device according to claim 2, characterized in that, The rotary drive mechanism (4) is connected to the platform (2) to drive the platform (2) to rotate around the central axis.

5. A three-dimensional scanning inspection method for wafer bonding slip, employing the inspection device according to any one of claims 1-4, characterized in that, The detection method includes the following steps: Step 1: Calibrate the detection device and obtain the system resolution R, whereby the system resolution represents the minimum displacement that the detection device can reliably resolve; Step 2: Full-circumference three-dimensional scanning. Place the bonding wafer pair (10) to be tested on the stage (2). Use the rotation drive mechanism (4) to make the detection module (3) and the wafer pair (10) rotate 360° relative to each other. During the relative motion, continuously collect the morphology data of the edge of the wafer pair (10) to obtain the original data covering the entire circumference of the wafer pair (10). Step 3: Process the collected data to restore the complete three-dimensional morphology of the wafer pair (10) edge; Step 4: Radial distance measurement and slip determination. Extract the radial positions of the upper wafer (11) edge and the lower wafer (12) edge at each angle from the restored three-dimensional morphology, and measure the radial distance D of the upper and lower wafer edges at each angle. If there is any angle θ that makes D exceed the preset slip threshold T, the wafer is determined to have a slip defect; otherwise, it is determined to be qualified. Wherein, the slider threshold T is not less than the system resolution R.

6. The method for three-dimensional scanning and inspection of wafer bonding slips according to claim 5, characterized in that, The detection method also includes: Step 5: Machine stability analysis and automatic compensation. Statistical analysis is performed on the D data of the same batch of wafers to calculate the average radial distance at each angle. Based on the distribution law of radial distance with angle, the systematic offset trend of the machine is identified, the compensation value is calculated and sent to the bonding machine for adjustment.

7. The three-dimensional scanning detection method for wafer bonding slips according to claim 5, characterized in that, In step 1, the system resolution R is obtained through the following method: Select a standard calibration piece of known size and perform repeated measurements. Calculate the standard deviation σ of the measured values ​​and set the system resolution R = kσ, where k is the confidence coefficient.

8. The three-dimensional scanning detection method for wafer bonding slips according to claim 5, characterized in that, In step 4, the slider threshold T is set according to the maximum allowable offset of the process.

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