Wafer level detection device

Abstract

The utility model discloses a wafer level detection device. The wafer level detection device comprises a light source, a bearing module, a transmission film and a camera, the light source and the camera are respectively arranged on two sides of the transmission film; the light source is used for emitting light beams to the sub-optical elements on the wafer to be detected, and the sub-optical elements modulate the light beams into corresponding light field distribution; the bearing module is used for bearing and fixing a to-be-detected wafer, and the bearing module is arranged to be movable relative to the light source, so that any sub-optical element on the to-be-detected wafer can be aligned with the center of the light source; the transmission film is used for receiving light field distribution; the camera is used for shooting light field distribution on the transmission film, a shot image is used for detecting optical performance parameters of the corresponding sub optical element, and the camera is set to be in a non-overexposure state. According to the invention, the wafer detection time can be effectively shortened, the wafer detection efficiency is improved, and thus a large batch of wafers can be rapidly detected.

Description

Technical Field

[0001] This application relates to the field of optics, and more particularly to a wafer-level inspection device. Background Technology

[0002] Optical components such as superlenses and molded gratings are generally manufactured in wafer-level mass production. A single wafer contains a large number of sub-optical components. Sub-optical components are optical components that are fabricated simultaneously on a single wafer by a single exposure. In order to ensure that the optical performance of all sub-optical components on the entire wafer manufactured in a single exposure is qualified, all sub-optical components need to be tested to obtain optical performance parameters used to evaluate the sub-optical components.

[0003] Because a single wafer contains a large number of sub-optical elements, each of which requires performance testing, traditional performance testing involves using a camera and grayscale image data processing to test the performance of individual optical elements. Therefore, the wafer is typically diced first to extract the sub-optical elements, and then each sub-optical element is tested individually to obtain its optical performance parameters. However, given the large number of sub-optical elements on a single wafer, cutting all the sub-optical elements from the wafer for performance testing during mass production is time-consuming. Furthermore, grayscale images captured by a camera are prone to information loss, leading to low accuracy in performance testing. Utility Model Content

[0004] To address the aforementioned technical problems, this application provides a wafer-level inspection device. This application controls the movement of the wafer to be inspected via a movable carrier module, and records image data of the light field distribution modulated by sub-optical elements on a transmission film using a camera in a non-overexposed state. Based on the captured images, the optical performance parameters of the sub-optical elements are detected. This allows for the rapid and accurate acquisition of the optical performance parameters of each sub-optical element with fewer shots, without dicing the wafer, thereby improving the efficiency of wafer inspection and enabling rapid inspection of wafers produced in large quantities.

[0005] According to one aspect of the embodiments of this application, a wafer-level inspection device is provided, the wafer inspection device comprising: a light source, a carrier module, a transmission film, and a camera;

[0006] The light source and the camera are respectively disposed on both sides of the transmission film;

[0007] The light source is used to emit a light beam toward a sub-optical element on the wafer to be inspected, and the sub-optical element modulates the light beam into a corresponding light field distribution.

[0008] The carrier module is used to carry and fix the wafer to be tested, and the carrier module is configured to be movable relative to the light source, so that any sub-optical element on the wafer to be tested can be aligned with the center of the light source;

[0009] The transmission film is used to receive the light field distribution; the camera is used to capture the light field distribution on the transmission film, and the captured image is used to detect the optical performance parameters of the corresponding sub-optical element, wherein the camera is set to a non-overexposure state.

[0010] In an exemplary embodiment of this application, the area of ​​the transmission film is larger than the coverage area of ​​the light field distribution.

[0011] In an exemplary embodiment of this application, the field of view of the camera covers the coverage area of ​​the light field distribution.

[0012] In an exemplary embodiment of this application, the difference in transmittance at various points on the transmission film is within a preset range.

[0013] In one exemplary embodiment of this application, the preset range is -2% to 2%.

[0014] In an exemplary embodiment of this application, the line connecting the center of the light source and the center of the camera is perpendicular to the transmission film.

[0015] In an exemplary embodiment of this application, the difference between the distance between the light source and the currently detected sub-optical element on the wafer to be tested and the working distance of the currently detected sub-optical element is within a preset tolerance range.

[0016] In an exemplary embodiment of this application, the preset tolerance range is -0.02mm to 0.02mm.

[0017] In one exemplary embodiment of this application, the light source is configured to be movable and rotatable.

[0018] The wafer inspection apparatus provided in this application includes: a light source, a carrier module, a transmission film, and a camera; the light source and the camera are respectively disposed on opposite sides of the transmission film; the light source is used to emit a light beam to a sub-optical element on the wafer to be inspected, and the sub-optical element modulates the light beam into a corresponding light field distribution; the carrier module is used to carry and fix the wafer to be inspected, and the carrier module is configured to be movable, so that any sub-optical element on the wafer to be inspected can be aligned with the center of the light source; the transmission film is used to receive the light field distribution; the camera is used to capture the light field distribution on the transmission film, and the captured image is used to detect the optical performance parameters of the corresponding sub-optical element, wherein the camera is configured to be in a non-overexposure state. This application controls the movement of the wafer to be inspected through a movable carrier module, and records image data of the light field distribution modulated by the sub-optical elements on the transmission film through a camera in a non-overexposed state. Based on the captured images, the optical performance parameters of the sub-optical elements are detected. Without cutting the wafer, the optical performance parameters of each sub-optical element can be obtained quickly and accurately with fewer shots, thereby improving the efficiency of wafer inspection and enabling rapid inspection of wafers produced in large quantities.

[0019] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0020] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0021] The above and other objectives, features and advantages of this application will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0022] Figure 1 A schematic diagram of the structure of a wafer-level inspection device provided in an embodiment of this application is shown.

[0023] Figure 2 A schematic diagram of the structure of a wafer-level inspection device provided in an embodiment of this application is shown.

[0024] Figure 3 A flowchart of a wafer-level inspection method provided in an embodiment of this application is shown.

[0025] Figure 4 A schematic diagram of a wafer-level inspection method provided in an embodiment of this application is shown.

[0026] Figure 5 A schematic diagram of image data correction for a wafer-level inspection method provided in an embodiment of this application is shown.

[0027] Figure 6 A grayscale image of a sub-optical element for projecting a dot matrix light spot, provided in an embodiment of this application, is shown.

[0028] Figure 7 A grayscale image of a sub-optical element for projecting a line-shaped light spot, provided in an embodiment of this application, is shown.

[0029] Figure 8 A grayscale image of a sub-optical element for homogenizing light provided in an embodiment of this application is shown.

[0030] Figure 9 A grayscale image of a collimating sub-optical element provided in one embodiment of this application is shown.

[0031] Figure label:

[0032] 1-Light source; 2-Transmission film; 3-Camera; 4-Wafer to be inspected. Detailed Implementation

[0033] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided to make the description of this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0034] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details are provided in the following description to give a full understanding of exemplary embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced by omitting one or more of the specific details, or other modules, components, etc., can be employed. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0035] In existing technologies, wafer-level mass production technology is generally used to mass-produce diffraction elements such as superlenses and molded gratings. A single wafer contains a large number of sub-optical elements. Before shipment, all sub-optical elements on the wafer usually need to be tested to determine whether their performance meets the standards. Current performance testing is performed on individual optical elements using cameras and grayscale image data processing. Therefore, the wafer needs to be diced first to cut out each sub-optical element, and then each sub-optical element is tested separately to obtain the optical performance parameters of each sub-optical element on the wafer. However, the number of sub-optical elements on a single wafer is large. In mass production, cutting out all the sub-optical elements on the wafer and then performing performance testing is time-consuming. Furthermore, grayscale images captured by cameras are prone to information loss, resulting in low accuracy of performance testing and making it unsuitable for batch testing.

[0036] To overcome the aforementioned deficiencies in related technologies, this application provides a wafer-level inspection device. This application controls the movement of the wafer to be inspected via a movable carrier module, and records image data of the light field distribution modulated by sub-optical elements on a transmission film using a camera in a non-overexposed state. Based on the captured images, the optical performance parameters of the sub-optical elements are detected. This allows for the rapid and accurate acquisition of the optical performance parameters of each sub-optical element with fewer shots, without dicing the wafer, thereby improving the efficiency of wafer-level inspection and enabling rapid inspection of wafers produced in large quantities.

[0037] This application provides a wafer-level inspection device, such as... Figure 1 As shown, Figure 1 A schematic diagram of a wafer-level inspection device according to an embodiment of this application is shown. The wafer-level inspection device includes: a light source 1, a support module (not shown in the figure), a transmission film 2, and a camera 3. It should be noted that the mechanical structures (e.g., the support module, guide rails, etc.) used to fix, support, and move the components are not shown. Figure 1 As shown in the image. Additionally... Figure 1 For example only. Figure 1 All components of the wafer-level inspection device shown are placed horizontally, but they can also be placed vertically. This application does not limit the specific placement angle.

[0038] Specifically, light source 1 and camera 3 are respectively positioned on opposite sides of transmission film 2. The design of light source 1 is matched to the sub-optical elements on the wafer 4 under test; that is, the operating wavelength of light source 1 is consistent with the operating wavelength of the sub-optical elements on the wafer 4 under test, and the working distance from the emitting surface of light source 1 to the structural surface of the sub-optical element is the designed working distance (e.g., focal length). Here, the structural surface refers to the surface on the sub-optical element where nanostructures are formed. In this configuration, light source 1 emits a light beam towards the sub-optical elements on the wafer 4 under test. When the light beam illuminates the sub-optical elements, the sub-optical elements modulate the beam into a specific light field distribution. It should be noted that the radius of the coverage area of ​​the light beam emitted by light source 1 on the wafer 4 under test is greater than the radius of any sub-optical element, but less than the center-to-center distance between any two sub-optical elements on the wafer 4 under test. This ensures that the light beam emitted by light source 1 illuminates only one sub-optical element, avoiding crosstalk between multiple sub-optical elements and affecting detection accuracy.

[0039] The carrier module is a mechanical component used to carry and fix the wafer 4 to be inspected. The specific fixing method is not limited; for example, it can be gripping, clamping, etc. The carrier module is set to be movable relative to the light source 1 and is controlled by the electric control module (not shown in the figure) of the wafer-level inspection device. This allows the wafer-level inspection device to change the spatial position of the wafer 4 to be inspected by controlling the carrier module, thereby ensuring that any sub-optical element on the wafer 4 can be aligned with the center of the light source for subsequent inspection processes. In this case, if the light source 1 is fixed, the entire wafer 4 can be inspected simply by changing its spatial position, shortening the inspection time and improving inspection efficiency. It should be noted that the carrier module is actually composed of multiple different mechanical parts. This application does not limit the movement mode of the carrier module. The carrier module can be moved relative to the light source as a whole; or the part of the carrier module used to fix the wafer to be tested can be moved relative to the light source; or the carrier module can be set to be fixed, and the performance testing of all sub-optical elements on the entire wafer to be tested can be achieved by controlling the movement of the movable light source 1 and aligning the center of the light source 1 with the sub-optical element to be tested.

[0040] The transmission film 2 is used to receive the light field distribution modulated by the sub-optical element. After the light field distribution modulated by the sub-optical element is irradiated onto the transmission film 2, it will propagate to the side of the transmission film 2 that is away from the light-emitting surface of the light source 1.

[0041] Camera 3 is positioned on the side of the transmission film 2 away from the light-emitting surface of the light source 1. The camera of camera 3 is used to capture the light field distribution on the transmission film 2 to obtain a light field image of the light field distribution modulated by the sub-optical element; the sensor of camera 3 has a sufficiently high resolution, and the acceptable operating wavelength range of the sensor covers the operating wavelength of the sub-optical element.

[0042] Furthermore, the camera in camera 3 is set to a non-overexposure state. The non-overexposure state primarily refers to the maximum receiving threshold of the camera's sensor. If the light intensity on the transmission film exceeds the sensor's maximum receiving threshold, the grayscale values ​​of all areas in the grayscale image captured by the camera where the light intensity exceeds the sensor's maximum receiving threshold will be recorded as the maximum grayscale value of 255. This will result in inaccurate grayscale values ​​in areas where the light intensity exceeds the sensor's maximum receiving threshold, causing information loss and affecting the accuracy of subsequent image data processing and performance testing. Therefore, this application sets the camera to a non-overexposure state to ensure that the grayscale values ​​corresponding to both the highlight and shadow areas in the grayscale image captured by the camera are accurately recorded, thereby improving the accuracy of performance testing of the sub-optical elements.

[0043] It should be noted that the wafer-level inspection apparatus provided in this application also includes an image processing device (not shown in the figure) for image data processing. The image processing device is used to process the light field image captured by the camera to obtain the optical performance parameters of the sub-optical element corresponding to the light field image, so as to complete the performance inspection of the sub-optical element.

[0044] In one embodiment, in order to fully receive the light field distribution modulated by the optical elements, the area of ​​the transmission film 2 is larger than the coverage area of ​​the light field distribution.

[0045] In one embodiment, in order to acquire square data comprehensively and clearly, the field of view (FOV) of camera 3 covers the coverage area of ​​the light field distribution.

[0046] In one embodiment, the difference in transmittance between different positions on the transmission film 2 and the light beam emitted by the light source 1 is within a preset range. This ensures that the difference in transmittance between any two positions on the transmission film 2 and the light beam emitted by the light source 1 is within the preset range, thereby ensuring uniform transmittance at all positions on the transmission film 2. Furthermore, the surface of the transmission film 2 is flat. In this case, it can be ensured that the brightness of the light spot modulated by the sub-optical element and projected onto the transmission film 2 is accurate, avoiding deviations, improving the uniformity and accuracy of the light field image, reducing performance detection errors caused by non-uniform transmittance during subsequent image processing, and improving the accuracy of performance testing of the sub-optical element.

[0047] In one embodiment, the preset range is -2% to 2%. Preferably, the transmittance of the light beam emitted by the light source 1 is uniform at each position on the transmission film 2, that is, the transmittance at each position on the transmission film 2 is equal.

[0048] In one embodiment, the line connecting the center of the light source 1 and the center of the camera 3 is perpendicular to the transmission film 2. For example... Figure 1 and Figure 2 As shown, Figure 1 and Figure 2 The dashed line in the diagram represents the line connecting the center of light source 1 and the center of camera 3.

[0049] In one embodiment, the distance between the light source 1 and the sub-optical element on the wafer 4 to be tested needs to be equal to the working distance of the sub-optical element. However, considering the tolerances that exist in the actual assembly process of the wafer-level inspection device, it is difficult to guarantee strict equality. Therefore, in this embodiment, the distance between the light source 1 and any sub-optical element on the wafer 4 to be tested should be within a reasonable tolerance range. That is, the difference between the distance between the light source 1 and the currently detected sub-optical element on the wafer 4 to be tested and the working distance of the currently detected sub-optical element is within a preset tolerance range. In this case, a reasonable tolerance range can ensure that the light field distribution modulated by the sub-optical element can be clearly presented on the transmission film 2, reducing the inaccuracy of the final performance test results due to assembly errors, thereby improving the accuracy of performance test.

[0050] Furthermore, the preset tolerance range is -0.02mm to 0.02mm. Preferably, the preset tolerance range is -0.015mm to 0.015mm. In this case, the upper and lower limits of the preset tolerance range can simplify assembly while ensuring the accuracy of performance test results.

[0051] In one embodiment, the light source 1 is configured to be movable and / or rotatable. In fact, the light source 1 can also be controlled by components such as sliding components and rotating components, so that the light source 1 can be moved and / or rotated. That is, the light source 1 can actually be configured to be movable, or it can be configured to be rotatable, or it can be both movable and rotatable, so that the light source can cooperate with the subsequent optical power calibration process and image data correction process.

[0052] In one embodiment, the optical performance parameters include one or more of the following: optical efficiency, spot uniformity, spot line length, spot condition, and collimation.

[0053] It should be emphasized that the wafer-level inspection device provided in this application can inspect a variety of different types of sub-optical elements. Specifically, it can be achieved by changing the light source 1 and controlling the working distance between the light source 1 and the wafer 4 to be inspected according to the design scheme of the sub-optical element. When performing performance testing on different types of sub-optical elements, the optical performance parameters to be tested can be selected.

[0054] For example, such as Figure 2 As shown, Figure 2 The diagram shows a schematic of the wafer-level inspection device provided in an embodiment of this application. Taking a dot-matrix projection sub-optical element with collimation function as an example, the main optical process in the inspection process is as follows: the divergent light emitted by the light source 1 illuminates a certain sub-optical element on the wafer 4 to be inspected. The nanostructure on this sub-optical element splits the light beam into multiple beams at different angles in an array, and then projects them onto the transmission film 2 to form diffuse reflection and transmission, specifically manifested as a discrete array of light spots. The camera 3 captures the light field distribution on the transmission film 2 and reads the corresponding grayscale image for subsequent inspection. In fact, the optical performance parameters of the sub-optical element used to project the dot-matrix light spots include optical efficiency and / or light spot uniformity.

[0055] For other types of sub-optical elements, the wafer-level inspection device differs only in the light field distribution on the light source 1 and the transmission film 2. For example, the light field distribution of a sub-optical element used to project a line-shaped light spot is a uniformly distributed line-shaped light spot that is divergent and homogenized within a specific FOI (Field of Illumination) range in one direction (e.g., the horizontal direction) and collimated in a direction perpendicular to this direction (e.g., the vertical direction). The optical performance parameters of the sub-optical element used to project the line-shaped light spot include one or more of optical efficiency, light spot line length, light spot linewidth, and light spot uniformity. The light field distribution of a sub-optical element used for homogenization is a uniformly distributed rectangular light spot that is divergent and homogenized at a specific FOI angle. The optical performance parameters of the sub-optical element used for homogenization include optical efficiency. The light field distribution of a sub-optical element used for collimation is a circular light spot within a small angular range. The optical performance parameters of the sub-optical element used for collimation include optical efficiency and / or collimation.

[0056] In one embodiment of this application, a wafer-level inspection method is provided, such as... Figure 3 As shown, Figure 3 A flowchart of a wafer-level inspection method provided in an embodiment of this application is shown. The wafer-level inspection method includes:

[0057] S10. Based on the light source, transmission film and camera, perform optical power calibration to obtain power correspondence value, wherein the power correspondence value represents the conversion mapping relationship between gray value and optical power value.

[0058] Specifically, images captured by a camera contain grayscale information. However, only the relative values ​​of the light field distribution can be obtained from the grayscale information. The relative values ​​of the light field distribution can be used to detect the uniformity of the light spot, but it is difficult to calculate the optical efficiency or other optical performance parameters that require accurate power values ​​from the relative values ​​of the light field distribution. Therefore, it is necessary to construct a power correspondence between the grayscale values ​​of the grayscale image and the light power values ​​of the light spot, that is, to establish a conversion mapping relationship between the grayscale values ​​and the actual energy distribution of the light field. The key operation is the light power calibration process.

[0059] In one embodiment, optical power calibration is performed based on the light source, the transmission film, and the camera to obtain corresponding power values, including:

[0060] The first power value of the light source is measured, and the light source is controlled to directly illuminate the transmission film; the transmission film is photographed by a camera to obtain a first grayscale image corresponding to the direct illumination of the transmission film by the light source; the grayscale values ​​of all pixels in the first grayscale image are summed to obtain a first grayscale value; the power correspondence value between the grayscale value and the power value is calculated based on the first power value and the first grayscale value.

[0061] First, the first power value I of the light source is measured using an optical power meter. Then, without placing the wafer under test, the light source is controlled to directly illuminate the transmission film, and the transmission film is then photographed using a camera, thus obtaining a first grayscale image of the light source directly illuminating the transmission film. Subsequently, the sum of the grayscale values ​​G of all pixels in the first grayscale image is calculated using an image processing device. sum The corresponding power value can be calculated based on the first power value obtained from the actual light source measured by the optical power meter. This refers to the conversion mapping relationship between grayscale values ​​and power values, that is, the power value corresponding to a grayscale value of 1 is... Subsequently, during the detection process, simply photographing the transmission film with a camera and reading the grayscale value of each pixel in the grayscale image will yield the power value corresponding to that pixel. For example, if the grayscale value of a pixel is g, then the power value corresponding to that pixel is g. The higher the camera's resolution and the denser the pixel sampling points, the more accurate the power correspondence between the grayscale value and the power value obtained through optical power calibration.

[0062] Furthermore, in one embodiment, to improve the accuracy of the power correspondence value, the power of the light source is modulated multiple times, and the power correspondence values ​​corresponding to different power light sources are calculated. The average value of all power correspondence values ​​is then taken as the final power correspondence value. Optionally, the movable light source can be controlled to move within the same horizontal plane parallel to the antireflection film, irradiating the antireflection film vertically multiple times from different positions. The power correspondence value corresponding to each irradiation of the antireflection film is calculated, and the average value of all power correspondence values ​​is taken as the final power average value.

[0063] S20. Based on the power correspondence value, calculate the power value distribution of the currently detected sub-optical element according to each grayscale image of the currently detected sub-optical element.

[0064] Specifically, firstly, based on the power correspondence value, the grayscale value on each grayscale image is converted into a power value, thereby obtaining the power value distribution of each sub-optical element. Then, based on the preset performance evaluation criteria, the optical performance parameters of each sub-optical element are calculated respectively. Finally, the performance evaluation of each sub-optical element is obtained through the optical performance parameters of each sub-optical element.

[0065] In one embodiment, based on the power correspondence value, the power value distribution corresponding to each sub-optical element is calculated according to the grayscale image of the currently detected sub-optical element, including:

[0066] Obtain the grayscale value distribution of the grayscale image of the currently detected sub-optical element; based on the power corresponding value, calculate the power value distribution corresponding to the currently detected sub-optical element according to the grayscale value distribution.

[0067] Specifically, grayscale value distribution refers to the grayscale distribution of each pixel in a grayscale image, while power value distribution refers to the power value distribution of light spots in the grayscale image. After acquiring a grayscale image of the currently detected sub-optical element, the camera first reads the grayscale value distribution corresponding to this grayscale image. Then, it can calculate the power value distribution of this grayscale image based on the conversion mapping relationship between grayscale values ​​and power values. The actual process is as follows: based on the grayscale value distribution of the grayscale image, the region where all light spots are located in the grayscale image is obtained, and the power value of each light spot in the grayscale image is calculated to obtain the power value distribution corresponding to the grayscale image.

[0068] It should be noted that, in the above embodiment, after the camera captures a grayscale image of the currently detected sub-optical element, the image processing device immediately calculates the power value distribution corresponding to this sub-optical element.

[0069] In another embodiment, all sub-optical elements can be photographed first, and then the power value distribution of the grayscale image corresponding to each sub-optical element can be calculated uniformly. That is, the camera can be used to traverse all sub-optical elements on the wafer to be tested to obtain the grayscale image corresponding to each sub-optical element.

[0070] Specifically, the process iterates through all sub-optical elements on the wafer to be inspected, obtaining a grayscale image corresponding to each sub-optical element, including:

[0071] The carrier module carrying the wafer to be tested is moved to sequentially align each sub-optical element on the wafer to be tested with the center of the light source; the camera is controlled to sequentially capture images of the transmission film to obtain a grayscale image corresponding to each sub-optical element.

[0072] To conduct batch testing and avoid the tedious operation of repeatedly fixing and switching the wafers under test, the most appropriate approach is to directly fix the wafers under test using a carrier module, and then move the carrier module via an electric control module to change the spatial position of the wafers under test and align the individual sub-optical elements on the wafers under test with the center of the light source, ensuring accurate working spacing. At this point, the grayscale image of the individual sub-optical elements on the wafers under test can be directly recorded. Then, while maintaining the spacing between the wafers under test and the light source, the wafers under test are moved sequentially so that the next sub-optical element is aligned with the center of the light source, and the recording is switched. The above steps are repeated until the grayscale image corresponding to each sub-optical element is obtained.

[0073] S30. Based on the power value distribution of the currently detected sub-optical element, calculate the optical performance parameters corresponding to the currently detected sub-optical element.

[0074] Specifically, based on preset performance evaluation criteria, the optical performance parameters of the currently tested sub-optical elements are calculated according to the power value distribution of the tested sub-optical elements. In other words, by calculating the performance distribution list of all sub-optical elements on the wafer under test, and using the sample product performance evaluation criteria, it is possible to determine whether the performance of the sub-optical elements is qualified. Figure 4 As shown, Figure 4 A schematic diagram of wafer-level inspection results provided in an embodiment of this application is shown.

[0075] The performance evaluation criteria for sub-optical elements vary depending on their intended use. Different types of sub-optical elements have their own corresponding performance evaluation standards, thus requiring the calculation of different optical performance parameters for different types of sub-optical elements. Among all optical performance parameters, an important indicator for evaluating sub-optical elements is optical efficiency. Optical efficiency refers to the ratio of the power value reaching the target effective light field to the power value output by the light source. Optical efficiency, to a certain extent, determines the application scenario of the sub-optical element. When using a light source of a certain power, the higher the optical efficiency of the sub-optical element, the greater the light energy reaching the target after passing through the sub-optical element, resulting in higher sensitivity and a longer detection distance for the device equipped with this sub-optical element.

[0076] Taking the sub-optical element for projecting a dot-matrix light spot as an example, after obtaining the grayscale image corresponding to this sub-optical element by taking a picture with a camera, each light spot is identified one by one, the grayscale values in a small area around the light spot are captured and summed, and after calculation according to the corresponding power value, the power value corresponding to each light spot can be obtained. The optical efficiency of this sub-optical element is the sum of the power values of each light spot divided by the first power value of the light source. Optionally, another optical performance parameter for evaluating the sub-optical element for projecting a dot-matrix light spot is the uniformity of the power values of each light spot.

[0077] Evaluating the optical efficiency of the sub-optical element for projecting a one-dimensional line light spot and the sub-optical element for light homogenization is the ratio of the sum of all values greater than e of the maximum power value in the light spot to the first power value of the light source. Optionally, the optical performance parameters for evaluating the sub-optical element for projecting a one-dimensional line light spot also include line width, line length, and uniformity. -2 It should be noted that the sub-optical element for collimation is different from the above three types of sub-optical elements. An important optical performance parameter for measuring the sub-optical element for collimation is the collimation degree, which can be calculated in principle by the change of the light spot radius at different distances of different transmission films. However, this method requires at least one change in the device structure for each single-point product tested, and the operation is relatively cumbersome. The method adopted in this application is to add a step of standard product calibration during the process of light power calibration, that is, to use a standard product with the same performance for calibration and record the collimated light spot power distribution of the standard product. During the actual test process, the difference between the light spot power distribution of the sub-optical element to be detected and the light spot power distribution of the standard product is calculated. If the sum of the total differences is less than the preset threshold of the sum of the light spot powers of the standard product, it is considered qualified. Therefore, it is only necessary to take a picture of the light spot image once to determine whether the collimation performance meets the standard.

[0078] After calculating the optical performance parameters of the currently detected sub-optical element, it is possible to judge whether the currently detected sub-optical element is qualified, and then complete the performance detection of the currently detected sub-optical element.

[0079] It should be noted that, similar to the previous embodiment of taking pictures of all sub-optical elements first, in fact, after the camera traverses all sub-optical elements on the wafer to be detected and obtains the grayscale image corresponding to each sub-optical element, the optical performance parameters of each sub-optical element can be calculated uniformly.

[0080]

[0081] In one embodiment, the wafer-level detection method further includes: constructing a normalization change function based on the light source, the transmission film, and the camera, where the normalization change function represents the mapping relationship between the grayscale value and the camera field angle of the camera.

[0082] ​First, based on the normalized change function, image data correction is performed on the grayscale image of the currently detected sub-optical element. Then, based on the power correspondence value, the power value distribution corresponding to the currently detected sub-optical element is calculated according to the grayscale image of the currently detected sub-optical element.

[0083] Specifically, theoretically, the transmittance of a transmission film for a normally incident light beam is approximately uniform. If a single-point collimated laser is used as the light source, and the emitted beam is controlled to enter the transmission film perpendicularly, and the light source is controlled to translate within a plane parallel to the transmission film, the grayscale values ​​of the laser spot in all grayscale images captured by the camera will be basically consistent. However, for cases where the beam is projected at a certain angle to cover the light spot, most of the beam illuminating the transmission film will have an angle of inclination, such as... Figure 2 As shown, the transmission and reflection energy of an obliquely incident beam differs from that of a normally incident beam. This difference in energy causes light spots with the same power to have unequal grayscale values ​​in the images captured by the camera due to the difference in incident angle. Furthermore, when a wide-angle camera captures a large field of view, the relative illumination (RI) differs between the center and edge fields of view, causing the grayscale values ​​of the captured images to decrease as the field of view increases. Under the influence of these two factors, the grayscale values ​​of the captured images do not directly reflect the true light field distribution on the transmission film, necessitating image data correction.

[0084] After the camera captures a grayscale image of the currently detected sub-optical element, to ensure the accuracy of the grayscale values, image data correction is first performed on the grayscale image according to a normalized transformation function. This means correcting the grayscale values ​​at various locations on the grayscale image based on the camera's field of view. If the grayscale data distribution of the acquired grayscale image is A(θ), then the corrected grayscale value is... Subsequently, based on the power corresponding value, calculations are performed on the grayscale image after image data correction to obtain the power value distribution of the grayscale image after image data correction, which is the power value distribution of the sub-optical element currently being detected.

[0085] It should be noted that θ = θ0 only when the distances from the light source and camera to the transmission film are the same; when the distances from the light source and camera to the transmission film are not the same, the camera field of view angle can be calculated based on the distance from the center of the light spot projected by the light source to the projection of the camera onto the transmission film, and the distance from the camera to the transmission film. This application only focuses on the grayscale images corresponding to different camera field of view angles. Although the angle of the light source will affect the oblique incidence transmission and reflection of the light beam to the transmission film, it will ultimately be superimposed on the grayscale image corresponding to the camera field of view angle in the form of data received by the camera.

[0086] Furthermore, the aforementioned image data correction process is strictly tied to the performance of the transmission film, the camera performance, and the fixed distance; that is, the performance of the transmission film, the camera performance, and the fixed distance cannot be changed. If they are changed, the image data correction must be performed again. However, the image data correction process is independent of the light source and the wafer 4 under test. Replacing the light source and the wafer 4 under test will allow a stable light field distribution to be formed on the transmission film.

[0087] In one embodiment, a normalized variation function is constructed based on the light source, the transmission film, and the camera, including:

[0088] The light source is controlled to rotate at a preset angle, so that the light source illuminates the transmission film at different light source angles in sequence until the light spot projected by the light source reaches the maximum field of view of the camera; the camera is controlled to take pictures of the transmission film in sequence to obtain the second grayscale images corresponding to different light source angles; the second power value corresponding to each second grayscale image is calculated, and the camera field of view angle corresponding to each second power value is obtained; a normalized variation function of grayscale value and camera field of view angle is constructed based on all second power values ​​and corresponding camera field of view angles.

[0089] Specifically, such as Figure 4 As shown, Figure 4 This diagram illustrates image data correction for a wafer-level inspection method according to an embodiment of this application. The positions of the transmission film and camera remain unchanged. A rotatable light source (e.g., a single-point collimated laser) directly illuminates the transmission film while maintaining constant power. The light source is rotated at a preset angle (e.g., 1°). During rotation, a second grayscale image corresponding to each light source angle is sequentially captured until the light spot projected by the light source reaches the maximum field of view of the camera. Then, based on the power correspondence value and the total grayscale value of each second grayscale image, a second power value corresponding to each second grayscale image is calculated. The camera field of view angle corresponding to each second power value is obtained, which is essentially obtaining the camera field of view angle corresponding to each light source angle. Thus, a normalized variation function of grayscale values ​​and camera field of view angles can be constructed based on all second power values ​​and camera field of view angles. This normalized variation function reflects the mapping relationship between grayscale image grayscale data and camera field of view angles under different light source angles and shooting field of view angles. Finally, taking the reciprocal of the normalized variation function can compensate for the grayscale value attenuation caused by field of view attenuation and oblique incident beams, thereby correcting the grayscale values ​​of the grayscale image. It should be noted that the terms "first" and "second" in the above-mentioned first grayscale image, first power value, second grayscale image, and second grayscale value are only used to distinguish the parameters.

[0090] For example, such as Figure 4 As shown, the light source is controlled at a light source angle θ0:θ 0,1 ,θ 0,2 ,θ 0,3 ,…,θ 0,nThe transmission film is illuminated sequentially, and the camera is controlled to capture the second grayscale image corresponding to each light source angle in sequence. The second power value I0:I corresponding to each second grayscale image is calculated. 0,1 ,I 0,2 ,I 0,3 ,…,I 0,n Obtain the camera field of view angle θ: θ1, θ2, θ3, ..., θ for each second grayscale image. n It should be noted that there is a one-to-one correspondence between the light source angle θ0, the second power value I0, and the camera field of view angle θ; then, the normalized variation function R(θ) can be obtained by fitting all the second power values ​​and all the camera field of view angles.

[0091] Example 1

[0092] like Figure 6 As shown, Figure 6 This image shows a grayscale image of a sub-optical element for projecting a dot matrix light spot, according to an embodiment of this application. In this embodiment, the sub-optical element is used to project a 5*3 dot matrix light spot. The beam emitted by a single-point VCSEL (Vertical-Cavity Surface-Emitting Laser) source is modulated at the wafer level optical radius to form a 5*3 dot matrix distribution on the transmission film. Calculations can obtain... Figure 6 The power value P of each light spot n The optical efficiency is calculated as follows: Where P0 is the first power value corresponding to the light source. To better utilize light energy, the optical efficiency η should be as high as possible. For example, a satisfactory performance standard could be an optical efficiency η greater than 65%.

[0093] Optionally, another optical performance parameter for evaluating the sub-optical element used to project the dot matrix light spots is the uniformity of the power values ​​of each spot. Since the power values ​​of each spot are already obtained, the uniformity of the spot power values ​​can be calculated. For example, the calculation method for the uniformity of one spot power value is as follows: Where ε represents the uniformity of the spot power value, P max P represents the power value of the most powerful light spot. min It is the power value of the weakest light spot. The more uniform the power of each light spot, the higher the power value. max and P min The closer the uniformity ε is to 100%, the better the performance of the sub-optical element. For example, a performance qualification standard could be a uniformity ε greater than 80%.

[0094] Example 2

[0095] like Figure 7 As shown, Figure 7 A grayscale image of a sub-optical element for projecting a line beam according to an embodiment of this application is shown. In this embodiment, the sub-optical element is used to project a line beam, and its function is to disperse the light beam emitted by the light source into a unidirectional, large-angle diverging line beam. When evaluating the performance of this sub-optical element, a value with a power greater than the maximum power value e within the line beam can be selected. -2 The sum of all values, denoted as the effective value P. L The formula for calculating optical efficiency is: Where P0 is the first power value corresponding to the light source. For example, a qualified performance standard could be an optical efficiency η greater than 80%.

[0096] Optional optical performance parameters for evaluating line spot performance include linewidth, line length, and uniformity, which can be calculated separately. Figure 7 The power value at the longitudinal edge of the beam spot drops to the maximum power value e -2 At the angular range, the power value at the lateral edge of the light spot drops to the maximum power value e. -2 The uniformity of the power distribution within the maximum value at the upper edge of the transverse section of the longitudinal center of the light spot, within the angular range, is easily calculated since the power distribution of the light spot has already been obtained.

[0097] Example 3

[0098] like Figure 8 As shown, Figure 8 A grayscale image of a sub-optical element for homogenizing light according to an embodiment of this application is shown. In this embodiment, the sub-optical element is used to homogenize the light beam emitted by a light source, and its function is to disperse and homogenize the light beam emitted by the light source into a uniform spot within a specific FOI angle range. Similar to a sub-optical element for projecting a line-shaped light spot, the FOI decreases from the edge power of the spot to the maximum power value e. -2 The optical efficiency is determined by the angular range at which the power within the light spot is greater than the maximum power value e. -2 The sum of all values ​​at point P D The ratio to the first power value P0 of the light source. For example, a performance qualification standard could be an optical efficiency η greater than 80%.

[0099] Example 4

[0100] like Figure 9 As shown, Figure 9 A grayscale image of a collimating sub-optical element provided in an embodiment of this application is shown. In this embodiment, the sub-optical element is used to collimate a light beam emitted by a light source; its function is to collimate a diverging light beam into a collimated beam. The optical efficiency of this sub-optical element is determined by the power within the light spot being greater than the maximum power value e. -2 The sum of all values ​​P CThe ratio to the first power value P0 of the light source. Exemplarily, the standard for qualified performance can be that the optical efficiency η is greater than 80%.

[0101] Moreover, an important optical performance parameter for measuring the sub-optical element for collimation is collimation. After the optical power is calibrated, the calibration of the standard product has been carried out. During the inspection process, the spot power distribution of the sub-optical element to be detected is subtracted from the spot power distribution of the standard product. If the sum of the total differences is less than the preset threshold of the sum of the spot powers of the standard product, it is qualified. Therefore, it is only necessary to take a spot image once to determine whether the collimation performance meets the standard. Exemplarily, the preset threshold can be 5%.

[0102] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and the practice of the utility model disclosed herein. The present application aims to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include the well-known common knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and the embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the appended claims.

Claims

1. A wafer-level inspection device, characterized in that, The wafer-level inspection device includes: a light source, a carrier module, a transmission film, and a camera; The light source and the camera are respectively disposed on both sides of the transmission film; The light source is used to emit a light beam toward a sub-optical element on the wafer to be inspected, and the sub-optical element modulates the light beam into a corresponding light field distribution. The carrier module is used to carry and fix the wafer to be tested, and the carrier module is configured to be movable relative to the light source, so that any sub-optical element on the wafer to be tested can be aligned with the center of the light source; The transmission film is used to receive the light field distribution; the camera is used to capture the light field distribution on the transmission film, and the captured image is used to detect the optical performance parameters of the corresponding sub-optical element, wherein the camera is set to a non-overexposure state.

2. The wafer-level inspection device according to claim 1, characterized in that, The area of ​​the transmission film is larger than the coverage area of ​​the light field distribution.

3. The wafer-level inspection device according to claim 1, characterized in that, The field of view of the camera covers the coverage area of ​​the light field distribution.

4. The wafer-level inspection device according to claim 1, characterized in that, The difference in transmittance at various points on the transmission film is within a preset range.

5. The wafer-level inspection device according to claim 4, characterized in that, The preset range is -2% to 2%.

6. The wafer-level inspection device according to claim 1, characterized in that, The line connecting the center of the light source and the center of the camera is perpendicular to the transmission film.

7. The wafer-level inspection device according to claim 1, characterized in that, The difference between the distance between the light source and the currently detected sub-optical element on the wafer to be tested and the working distance of the currently detected sub-optical element is within a preset tolerance range.

8. The wafer-level inspection device according to claim 7, characterized in that, The preset tolerance range is -0.02mm to 0.02mm.

9. The wafer-level inspection device according to claim 1, characterized in that, The optical performance parameters include one or more of the following: optical efficiency, spot uniformity, spot line length, spot linewidth, and collimation.

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