Wafer level detection device and wafer level detection method

Abstract

The invention discloses a wafer level detection device and a wafer level detection method. 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] The present application relates to the field of optics, and in particular to a wafer-level detection device and a wafer-level detection method. Background Art

[0002] Optical elements such as superlenses and molded gratings are generally manufactured in wafer-level mass production. A single wafer contains a large number of sub-optical elements. Sub-optical elements are optical elements obtained by simultaneously preparing multiple optical elements on a wafer through a single exposure. In order to ensure that the optical performance of all sub-optical elements on a whole wafer manufactured in a single time is qualified, all sub-optical elements need to be tested to obtain optical performance parameters for evaluating the sub-optical elements.

[0003] Since there are a large number of sub-optical components on a single wafer, each of them needs to be tested for performance. Traditionally, performance testing is performed on a single optical component through camera and grayscale image data processing. Therefore, the wafer is usually cut first to cut out the sub-optical components on the wafer, and then each sub-optical component is tested for performance, thereby obtaining the optical performance parameters of each sub-optical component on the wafer. However, there are a large number of sub-optical components on a single wafer. When mass production is carried out, it takes a long time to cut out all the sub-optical components on the wafer and then perform performance testing. In addition, the grayscale images taken by the camera are prone to information loss, which leads to low accuracy of performance testing. Summary of the invention

[0004] In response to the above technical problems, the present application provides a wafer-level detection device and a wafer-level detection method. The present application controls the movement of the wafer to be detected through a movable carrying module, and records the image data of the light field modulated by the sub-optical element on the transmission film through a camera in a non-overexposed state, and then detects the optical performance parameters of the sub-optical element based on the captured image. Without cutting the wafer, the optical performance parameters of each sub-optical element can be quickly and accurately obtained through a small number of shots, thereby improving the efficiency of wafer detection, and then being able to quickly detect wafers produced in large quantities.

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

[0006] The light source and the camera are respectively arranged on two sides of the transmissive film;

[0007] The light source is used to emit a light beam to the 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 carrying module is used to carry and fix the wafer to be inspected, and the carrying module is configured to be movable relative to the light source, so that any sub-optical element on the wafer to be inspected 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 photograph the light field distribution on the transmission film, and the photographed 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 the present application, the area of ​​the transmission film is larger than the coverage range of the light field distribution.

[0011] In an exemplary embodiment of the present application, the field of view of the camera covers the coverage range of the light field distribution.

[0012] In an exemplary embodiment of the present application, the difference between the transmittances at various locations on the transmissive film is within a preset range.

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

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

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

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

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

[0018] According to one aspect of an embodiment of the present application, a wafer-level detection method is provided, the wafer-level detection method comprising:

[0019] Performing optical power calibration based on the light source, the transmissive film and the camera to obtain a power corresponding value, wherein the power corresponding value represents a conversion mapping relationship between a grayscale value and an optical power value;

[0020] Based on the power corresponding value, a calculation is performed according to the grayscale image of the currently detected sub-optical element to obtain a power value distribution corresponding to the currently detected sub-optical element;

[0021] According to the power value distribution of the currently detected sub-optical element, the optical performance parameter corresponding to the currently detected sub-optical element is calculated.

[0022] In an exemplary embodiment of the present application, the wafer-level detection method further includes:

[0023] constructing a normalized variation function based on the light source, the transmission film and the camera, wherein the normalized variation function represents a mapping relationship between the grayscale value and the camera field of view angle of the camera;

[0024] First, based on the normalized variation function, image data correction is performed on the grayscale image of the currently detected sub-optical element, and then based on the power corresponding value, calculation is performed according to the grayscale image of the currently detected sub-optical element to obtain the power value distribution corresponding to the currently detected sub-optical element.

[0025] The wafer inspection device provided in the embodiment of the present application includes: a light source, a supporting module, a transmissive film and a camera; the light source and the camera are respectively arranged on both sides of the transmissive film; the light source is used to emit a light beam to the 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 supporting module is used to support and fix the wafer to be inspected, and the supporting 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 transmissive film is used to receive the light field distribution; the camera is used to shoot the light field distribution on the transmissive film, and the image obtained is used to detect the optical performance parameters of the corresponding sub-optical element, wherein the camera is set to a non-overexposure state. The present application controls the movement of the wafer to be inspected through a movable carrying module, and records the image data of the light field modulated by the sub-optical element on the transmission film through a camera in a non-overexposed state, and then detects the optical performance parameters of the sub-optical element based on the captured image. Without cutting the wafer, the optical performance parameters of each sub-optical element can be quickly and accurately obtained through a small number of shots, thereby improving the efficiency of wafer inspection and enabling rapid inspection of wafers produced in large quantities.

[0026] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0029] Figure 1 A schematic structural diagram of a wafer-level detection device provided in one embodiment of the present application is shown.

[0030] Figure 2 A schematic structural diagram of a wafer-level detection device provided in one embodiment of the present application is shown.

[0031] Figure 3 A flow chart of a wafer-level detection method provided by an embodiment of the present application is shown.

[0032] Figure 4 A detection schematic diagram of a wafer-level detection method provided in an embodiment of the present application is shown.

[0033] Figure 5 A schematic diagram of image data correction of a wafer-level inspection method provided in an embodiment of the present application is shown.

[0034] Figure 6 A grayscale image of a sub-optical element for projecting a dot matrix light spot provided by an embodiment of the present application is shown.

[0035] Figure 7 A grayscale image of a sub-optical element for projecting a word line light spot provided by an embodiment of the present application is shown.

[0036] Figure 8 A grayscale image of a sub-optical element for light homogenization provided in an embodiment of the present application is shown.

[0037] Fig. 9 A grayscale image of a sub-optical element for collimation provided by an embodiment of the present application is shown.

[0038] Reference numerals:

[0039] 1-light source; 2-transmissive film; 3-camera; 4-wafer to be inspected. DETAILED DESCRIPTION

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0041] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application unclear.

[0042] In the prior art, wafer-level mass production manufacturing technology is generally used to mass-produce diffraction elements such as super-lenses and molded gratings. A single wafer contains a large number of sub-optical elements. Before shipment, it is usually necessary to test all sub-optical elements on the wafer to determine whether their performance meets the standards. The current performance test is to perform performance testing on a single optical element by means of camera and grayscale image data processing. Therefore, it is necessary to first cut the wafer, cut out each sub-optical element on the wafer, and then perform performance testing on each sub-optical element separately, so as 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. When mass production is carried out, it takes a long time to cut out all the sub-optical elements on the wafer and then perform performance testing. In addition, the grayscale image taken by the camera is prone to information loss, resulting in low accuracy of performance testing, which is not suitable for batch testing.

[0043] In order to overcome the above-mentioned defects of the related art, the present application provides a wafer-level detection device and a wafer-level detection method. The present application controls the movement of the wafer to be detected through a movable carrying module, and records the image data of the light field modulated by the sub-optical element on the transmission film through a camera in a non-overexposed state, and then detects the optical performance parameters of the sub-optical element based on the captured image. Without cutting the wafer, the optical performance parameters of each sub-optical element can be quickly and accurately obtained through a small number of shots, thereby improving the efficiency of wafer-level detection, and then being able to quickly detect wafers produced in large quantities.

[0044] The present application provides a wafer-level detection device, such as Figure 1 As shown, Figure 1 The schematic diagram of the structure of a wafer-level detection device provided in an embodiment of the present application is shown, and the wafer-level detection device includes: a light source 1, a carrying module (not shown in the figure), a transmission film 2 and a camera 3. It should be noted that the mechanical structure for fixing, supporting and moving each component (such as the carrying module, the guide rail and other components) is not shown in the figure. Figure 1 In addition, Figure 1 For example only, Figure 1All components of the wafer-level inspection device shown in the figure are placed horizontally, but in fact they can also be placed vertically, and the present application does not limit the specific placement angle.

[0045] Specifically, the light source 1 and the camera 3 are respectively arranged on both sides of the transmission film 2. The light source 1 matches the design scheme of the sub-optical element on the wafer 4 to be detected, that is, the working wavelength of the light source 1 is consistent with the working wavelength of the sub-optical element on the wafer 4 to be detected, and the working distance from the light emitting surface of the light source 1 to the structural surface of the sub-optical element is the working distance of the design scheme (such as focal length), wherein the structural surface refers to the surface on which the nanostructure is arranged on the sub-optical element. In this case, the light source 1 is used to emit a light beam to the sub-optical element on the wafer 4 to be detected. When the light beam irradiates the sub-optical element, the sub-optical element modulates the light beam into a specific light field distribution. It should be noted that the coverage radius of the light beam emitted by the light source 1 on the wafer 4 to be detected is greater than the radius of any sub-optical element, and is less than the center distance between any two sub-optical elements on the wafer 4 to be detected. In this case, it can be ensured that the light beam emitted by the light source 1 is only irradiated to one sub-optical element, avoiding crosstalk between multiple sub-optical elements and affecting the detection accuracy.

[0046] The carrying module is a mechanical component used to carry and fix the wafer 4 to be detected. The specific fixing method is not limited. Exemplarily, the fixing method can be grasping, clamping, etc. The carrying module is configured to be movable relative to the light source 1 and is controlled by an electric control module (not shown in the figure) of the wafer-level detection device, so that the wafer-level detection device can change the spatial position of the wafer 4 to be detected by controlling the carrying module, so that any sub-optical element on the wafer 4 to be detected can be aligned with the center of the light source to realize the subsequent detection process. In this case, if the light source 1 is fixed, the detection of the entire wafer 4 to be detected can be realized by only changing the spatial position of the wafer 4 to be detected, which shortens the detection time and improves the detection efficiency. It should be noted that the carrier module is actually composed of multiple different mechanical parts. The present application does not limit the movement method of the carrier module. The carrier module can be moved relative to the light source as a whole; or the partial structure on the carrier module used to fix the wafer to be inspected can be moved relative to the light source; or the carrier module can be set to be fixed, and the performance of all sub-optical elements on the entire wafer 4 to be inspected can be detected by controlling the movement of the movable light source 1 and aligning the center of the light source 1 with the sub-optical element currently to be detected.

[0047] The transmission film 2 is used to receive the light field distribution modulated by the sub-optical element. After irradiating the transmission film 2 , the light field distribution modulated by the sub-optical element will propagate to the side of the transmission film 2 away from the light emitting surface of the light source 1 .

[0048] The camera 3 is arranged on the side of the transmission film 2 away from the light emitting surface of the light source 1. The camera of the camera 3 is used to photograph 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 resolution of the sensor of the camera 3 is high enough, and the acceptable working wavelength range of the sensor covers the working wavelength of the sub-optical element.

[0049] In addition, the camera in camera 3 is set to a non-overexposure state. The non-overexposure state is mainly aimed at the maximum receiving threshold of the camera sensor. If the light intensity on the transmission film exceeds the maximum receiving threshold of the sensor, the grayscale values ​​of the areas where the light intensity exceeds the maximum receiving threshold of the sensor on the grayscale image captured by the camera are all recorded as the maximum grayscale value of 255, which will make the grayscale values ​​of the areas where the light intensity exceeds the maximum receiving threshold of the sensor on the grayscale image inaccurate, causing information loss, thereby affecting the accuracy of the performance test of the subsequent image data processing. Therefore, the present application sets the camera to a non-overexposure state, which can ensure that the grayscale values ​​corresponding to the highlight and dark parts of the grayscale image captured by the camera can be accurately recorded, thereby improving the accuracy of the performance test of the sub-optical element.

[0050] It should be noted that, in fact, the wafer-level detection device provided in the present 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 taken 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 detection of the sub-optical element.

[0051] In one embodiment, in order to completely receive the light field distribution modulated by the sub-optical element, the area of ​​the transmissive film 2 is larger than the coverage range of the light field distribution.

[0052] In one embodiment, in order to obtain the square data comprehensively and clearly, the field of view (FOV) of the camera 3 covers the coverage range of the light field distribution.

[0053] In one embodiment, the difference between the transmittances of the light beam emitted by the light source 1 at each position on the transmission film 2 is within a preset range, that is, the difference between the transmittances of the light beam emitted by the light source 1 at any two positions on the transmission film 2 is ensured to be within a preset range, thereby ensuring uniform transmittances at each position on the transmission film 2. In addition, the surface of the transmission film 2 is placed flat. In this case, it can be ensured that the brightness of the light spot modulated by the sub-optical element projected onto the transmission film 2 is accurate, avoiding deviations, improving the uniformity and accuracy of the light field image, reducing the performance detection error caused by uneven transmittance during subsequent image processing, and improving the accuracy of performance detection of the sub-optical element.

[0054] In one embodiment, the preset range is -2% to 2%. Preferably, the transmittance of each position on the transmissive film 2 to the light beam emitted by the light source 1 is uniform, that is, the transmittance of each position on the transmissive film 2 is equal.

[0055] In one embodiment, the line connecting the center of the light source 1 and the center of the camera 3 is perpendicular to the transmissive film 2. Figure 1 and Figure 2 As shown, Figure 1 and Figure 2 The dotted line in is the line connecting the center of the light source 1 and the center of the camera 3.

[0056] In one embodiment, the spacing between the light source 1 and the sub-optical element on the wafer 4 to be detected needs to be equal to the working spacing of the sub-optical element, but considering the tolerance of the wafer-level detection device in the actual assembly process, it is difficult to ensure strict equality. Therefore, in this embodiment, the spacing between the light source 1 and any sub-optical element on the wafer 4 to be detected should be within a reasonable tolerance range, that is, the difference between the spacing between the light source 1 and the sub-optical element currently being detected on the wafer 4 to be detected and the working spacing of the sub-optical element currently being detected 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, reduce the inaccuracy of the final performance test results due to assembly errors, and thereby improve the accuracy of performance testing.

[0057] Further, the preset tolerance range is -0.02 mm to 0.02 mm. Preferably, the preset tolerance range is -0.015 mm to 0.015 mm. In this case, the upper and lower limits of the preset tolerance range can simplify the assembly difficulty while ensuring the accuracy of the performance test results.

[0058] 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 a sliding component and a rotating component, so that the light source 1 can be moved and / or rotated, that is, in fact, the light source 1 can be configured to be movable, can be configured to be rotatable, can also be configured to be movable and rotatable, so that the light source can cooperate with the subsequent optical power calibration process and image data correction process.

[0059] In one embodiment, the optical performance parameter includes one or more of optical efficiency, light spot uniformity, light spot line length, light spot status and collimation.

[0060] It should be emphasized that the wafer-level detection device provided in the present application can detect a variety of different types of sub-optical elements. Specifically, it can be achieved by replacing the light source 1 and controlling the working distance between the light source 1 and the wafer 4 to be detected according to the design plan of the sub-optical element. When performing performance tests on different types of sub-optical elements, the optical performance parameters that need to be tested can be selected.

[0061] As an example, Figure 2 As shown, Figure 2 A structural schematic diagram of a wafer-level detection device provided by an embodiment of the present application is shown. Taking a dot matrix projection sub-optical element compatible with a collimation function as an example, the main optical process in the detection process is: the divergent light emitted by the light source 1 is irradiated onto a sub-optical element on the wafer 4 to be detected, and the nanostructure on this sub-optical element splits the light beam into multiple light beams at different angles in the form of an array, and then projects it onto the transmission film 2 to form diffuse reflection and transmission, which is specifically manifested as a light spot distributed in a discrete array. The camera 3 captures the light field distribution on the transmission film 2 and reads the corresponding grayscale image for subsequent detection. In fact, the optical performance parameters of the sub-optical element used to project the dot matrix light spot include optical efficiency and / or light spot uniformity.

[0062] For other types of sub-optical elements, the wafer-level detection device only uses different light sources 1 and light field distributions on the transmission film 2. For example, the light field distribution of the sub-optical element used to project a line of light spot is divergent and uniformly distributed in a specific FOI (Field of Illumination, illumination coverage angle) range in one direction (such as the horizontal direction), and the overall line of light spot is collimated in a direction perpendicular to this direction (such as the vertical direction). The optical performance parameters of the sub-optical element used to project the line of light spot include one or more of optical efficiency, light spot line length, light spot line width and light spot uniformity; the light field distribution of the sub-optical element used for uniform light is an overall rectangular light spot divergent and uniformly distributed at a specific FOI angle, and the optical performance parameters of the sub-optical element used for uniform light include optical efficiency; the light field distribution of the sub-optical element used for collimation is a circular light spot within a small angle range, and the optical performance parameters of the sub-optical element used for collimation include optical efficiency and / or collimation.

[0063] In one embodiment of the present application, a wafer-level detection method is provided, such as Figure 3 As shown, Figure 3 A flowchart of a wafer-level detection method provided by an embodiment of the present application is shown. The wafer-level detection method includes:

[0064] S10, performing optical power calibration based on the light source, the transmission film and the camera to obtain a power corresponding value, wherein the power corresponding value represents a conversion mapping relationship between the grayscale value and the optical power value.

[0065] Specifically, the image captured by the camera contains grayscale value information, and only the relative value of the light field distribution can be obtained based on the grayscale value information. The relative value 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 ​​through the relative value of the light field distribution. Therefore, it is necessary to construct a power correspondence between the grayscale value of the grayscale image and the light power value of the light spot, that is, to establish a conversion mapping relationship between the grayscale value and the actual energy distribution of the light field, and the key operation is the optical power calibration process.

[0066] In one embodiment, the optical power is calibrated based on the light source, the transmission film and the camera to obtain the corresponding power value, including:

[0067] The first power value of the light source is measured, and the light source is controlled to directly irradiate the transmissive film; the transmissive film is photographed based on a camera to obtain a first grayscale image corresponding to the light source directly irradiating the transmissive film; the grayscale values ​​of all pixels in the first grayscale image are summed to obtain a first grayscale value; and calculation is performed based on the first power value and the first grayscale value to obtain power corresponding values ​​of the grayscale value and the power value.

[0068] First, the first power value I of the light source is measured by an optical power meter. Then, without placing the wafer to be inspected, the light source is controlled to directly irradiate the transmissive film. The transmissive film is then photographed by a camera, thereby obtaining a first grayscale image when the light source directly irradiates the transmissive film. Subsequently, the sum of the grayscale values ​​of all pixels in the first grayscale image is calculated by an image processing device. sum , and the corresponding power value can be calculated based on the first power value of the light source measured by the optical power meter That is, the conversion mapping relationship between grayscale value and power value, that is, the power value corresponding to 1 grayscale value is After that, during the detection process, as long as the camera is used to shoot the transmissive film and the grayscale value of each pixel in the grayscale image is read, the power value corresponding to this pixel can be obtained. For example, if the grayscale value of a pixel is g, the power value corresponding to this pixel is The higher the resolution of the camera 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.

[0069] Furthermore, in one embodiment, in order to improve the accuracy of the power corresponding value, the power of the light source is modulated multiple times, and the power corresponding values ​​corresponding to light sources with different powers are calculated, and then the average value of all the power corresponding values ​​is taken as the final power corresponding value. Optionally, the movable light source can also be controlled to move in the same horizontal plane parallel to the anti-reflection film, and the anti-reflection film is vertically irradiated multiple times at different positions, and the power corresponding value corresponding to each irradiation of the anti-reflection film is calculated, and the average value of all the power corresponding values ​​is taken as the final power average value.

[0070] S20, based on the power corresponding value, calculate according to each grayscale image of the sub-optical element currently detected to obtain the power value distribution corresponding to the sub-optical element currently detected.

[0071] Specifically, based on the power corresponding value, the grayscale value on each grayscale image is converted into a power value, and then the power value distribution corresponding to each sub-optical element is obtained, and then based on the preset performance evaluation criteria, the optical performance parameters corresponding to each sub-optical element are calculated respectively, and finally the performance evaluation of each sub-optical element is obtained through the optical performance parameters corresponding to each sub-optical element.

[0072] In one embodiment, based on the power corresponding value, the power value distribution corresponding to each sub-optical element is obtained by calculation according to the grayscale image of the currently detected sub-optical element, including:

[0073] The grayscale value distribution of the grayscale image of the currently detected sub-optical element is obtained; based on the power corresponding value, calculation is performed according to the grayscale value distribution to obtain the power value distribution corresponding to the currently detected sub-optical element.

[0074] Specifically, the grayscale value distribution refers to the grayscale distribution of each pixel on the grayscale image, and the power value distribution refers to the power value distribution of the light spot on the grayscale image. After the camera obtains the grayscale image of the sub-optical element currently being detected, it first reads the grayscale value distribution corresponding to the grayscale image, and then calculates the power value distribution of the grayscale image based on the conversion mapping relationship between the grayscale value and the power value. The actual process is: identify according to the grayscale value distribution of the grayscale image, obtain the area where all the light spots on the grayscale image are located, calculate the power value of each light spot on the grayscale image, and obtain the power value distribution corresponding to the grayscale image.

[0075] It should be noted that, in the above embodiment, after the camera captures the grayscale image of the sub-optical element currently being detected, the image processing device immediately calculates the power value distribution corresponding to the sub-optical element.

[0076] In another embodiment, all sub-optical elements may be photographed first, and then the power value distribution of the grayscale image corresponding to each sub-optical element may be uniformly calculated, that is, all sub-optical elements on the wafer to be inspected may be traversed by the camera first to obtain the grayscale image corresponding to each sub-optical element.

[0077] Specifically, all sub-optical elements on the wafer to be inspected are traversed to obtain a grayscale image corresponding to each sub-optical element, including:

[0078] The carrying module carrying the wafer to be inspected is controlled to move, and each sub-optical element on the wafer to be inspected is aligned with the center of the light source in turn; the camera is controlled to photograph the transmission film in turn to obtain a grayscale image corresponding to each sub-optical element.

[0079] In order to carry out batch testing and avoid the tedious operation of fixing and switching the wafers to be inspected multiple times, the most appropriate method is to directly fix the wafers to be inspected through the carrying module, and then control the movement of the carrying module through the electric control module, so as to change the spatial position of the wafer to be inspected and align the single sub-optical element in the wafer to be inspected with the center of the light source to ensure the accuracy of the working spacing. At this time, the grayscale image of a single sub-optical element on the wafer to be inspected can be directly recorded, and then the spacing between the wafer to be inspected and the light source is maintained, and the wafer to be inspected is moved in turn so that the next sub-optical element is aligned with the center of the light source to switch the recording, and the above steps are repeated until the grayscale image corresponding to each sub-optical element is obtained.

[0080] S30. Calculate the optical performance parameter corresponding to the currently detected sub-optical element according to the power value distribution of the currently detected sub-optical element.

[0081] Specifically, based on the preset performance evaluation criteria, the optical performance parameters corresponding to the currently detected sub-optical element are calculated according to the power value distribution corresponding to the currently detected sub-optical element, that is, the performance distribution list of all sub-optical elements on the wafer to be detected is obtained according to the calculation, and the performance evaluation criteria of the sample product are used to determine whether the performance of the sub-optical element is qualified, such as Figure 4 As shown, Figure 4 A schematic diagram showing wafer-level detection results provided by an embodiment of the present application is shown.

[0082] The performance evaluation criteria for sub-optical components with different purposes are inconsistent. Different types of sub-optical components have corresponding performance evaluation criteria. Therefore, different optical performance parameters need to be calculated for different types of sub-optical components. Among all the optical performance parameters, an important indicator for evaluating sub-optical components is optical efficiency. Optical efficiency refers to the ratio of the power value of the target effective light field to the power value output by the light source. Optical efficiency determines the application scenario of the sub-optical component to a certain extent. When using a light source of a certain power, the higher the optical efficiency of the sub-optical component, the greater the light energy reaching the target after passing through the sub-optical component, making the device with this sub-optical component more sensitive and with a longer detection distance.

[0083] Taking the sub-optical element used to project dot-matrix light spots as an example, after the grayscale image corresponding to the sub-optical element is obtained by shooting with a camera, each light spot is identified one by one, the grayscale value of a small area around the light spot is captured and summed, and the power value corresponding to each light spot is calculated according to the power corresponding value. 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 used to project dot-matrix light spots is the uniformity of the power values ​​of each light spot.

[0084] Evaluate the optical efficiency of the sub-optical element used to project a line spot and for light uniformity, which is greater than the maximum power value e in the spot. -2 Optionally, the optical performance parameters of the sub-optical element used to project a line light spot are also evaluated, such as line width, line length and uniformity.

[0085] It should be noted that the sub-optical element used for collimation is different from the above three types of sub-optical elements. An important optical performance parameter for measuring the sub-optical element used for collimation is collimation. In principle, it can be calculated by the change in the spot radius of different transmission films at distances. However, this method requires changing the device architecture at least once for each test of a single-point product, and the operation is relatively cumbersome. The method used in this application is to add a step of standard calibration during the optical power calibration process, that is, to calibrate with a standard product with the same performance, and record the collimation spot power distribution of the standard product. In the actual test process, the spot power distribution of the sub-optical element to be tested 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.

[0086] After the optical performance parameters of the currently detected sub-optical element are calculated, it can be judged whether the currently detected sub-optical element is qualified, thereby completing the performance test of the currently detected sub-optical element.

[0087] It should be noted that, similar to the aforementioned embodiment of photographing all sub-optical elements first, in fact, after the camera traverses all sub-optical elements on the wafer to be inspected and obtains the grayscale image corresponding to each sub-optical element, the optical performance parameters of each sub-optical element can be uniformly calculated.

[0088] In one embodiment, the wafer-level detection method further includes: constructing a normalized variation function based on the light source, the transmission film, and the camera, wherein the normalized variation function represents a mapping relationship between the grayscale value and the camera field of view angle of the camera;

[0089] First, based on the normalized variation function, image data correction is performed on the grayscale image of the currently detected sub-optical element, and then based on the power corresponding value, calculation is performed according to the grayscale image of the currently detected sub-optical element to obtain the power value distribution corresponding to the currently detected sub-optical element.

[0090] Specifically, in theory, the transmittance of the transmissive film for a normally incident light beam is approximately uniform. If a single-point collimated laser is used as the light source, the light beam emitted by the light source is controlled to vertically enter the transmissive film, and the light source is controlled to translate in a plane parallel to the transmissive film, the grayscale values ​​of the laser spot in all grayscale images captured by the camera are basically consistent. However, for the case of projecting a certain angle to cover the light spot, most of the light beams are irradiated on the transmissive film at an angle, such as Figure 2 As shown in the figure, at this time, there is a difference between the transmission and reflection energy of the oblique incident light beam and the transmission and reflection energy of the normal incident light beam, which will cause the grayscale values ​​of the image taken by the camera to be unequal due to the difference in incident angles for the light spots with the same power value. In addition, when a wide-angle camera shoots a large field of view image, there is a difference in the relative illumination (RI, Relative Illumination) between the central field of view and the edge field of view, and the grayscale value of the image taken by the camera will decay as the field of view angle increases. Under the influence of these two factors, the grayscale value of the grayscale image taken by the camera cannot directly reflect the actual situation of the light field distribution on the transmissive film, and image data correction is required.

[0091] After the subsequent camera captures the grayscale image of the currently detected sub-optical element, in order to ensure the accuracy of the grayscale value of the grayscale image, the grayscale image is first corrected according to the normalized change function, that is, the grayscale value corresponding to each position on the grayscale image is corrected according to the camera field of view. If the grayscale data distribution of the obtained grayscale image is A(θ), the corrected grayscale value is Subsequently, based on the power corresponding value, calculation is performed according to the grayscale image after image data correction, so as to obtain the power value distribution corresponding to the grayscale image after image data correction, that is, the power value distribution corresponding to the sub-optical element currently detected.

[0092] It should be noted that only when the distances from the light source and the camera to the transmissive film are consistent, θ=θ0; when the distances from the light source and the camera to the transmissive film are inconsistent, 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 on the transmissive film, and the distance from the camera to the transmissive film. This application only focuses on the grayscale images corresponding to different camera field of view angles. Although the light source angle will affect the oblique incidence, transmission and reflection of the light beam to the transmissive film, it will eventually be superimposed on the grayscale image corresponding to the camera field of view angle in the form of camera received data.

[0093] Furthermore, the above image data correction process is strictly bound to the performance of the transmission film, the performance of the camera and the fixed distance, that is, the performance of the transmission film, the performance of the camera and the fixed distance cannot be changed. If they are changed, the image data correction needs to be performed again. However, the image data correction process is independent of the light source and the wafer 4 to be detected. After replacing the light source and the wafer 4 to be detected, a stable light field distribution can be formed on the transmission film.

[0094] In one embodiment, a normalized variation function is constructed based on a light source, a transmission film, and a camera, including:

[0095] The light source is controlled to rotate at a preset angle so that the light source illuminates the transmissive film at different light source angles in turn until the light spot projected by the light source reaches the maximum field of view angle of the camera; the camera is controlled to photograph the transmissive film in turn to obtain second grayscale images corresponding to different light source angles; the second power value corresponding to each second grayscale image is calculated respectively, and the camera field of view angle corresponding to each second power value is obtained; and a normalized change function of the grayscale value and the camera field of view angle is constructed according to all the second power values ​​and the corresponding camera field of view angles.

[0096] Specifically, Figure 4 As shown, Figure 4 The image data correction schematic diagram of the wafer-level detection method provided by an embodiment of the present application is shown. The positions of the transmission film and the camera are kept unchanged, and a rotatable light source (such as a single-point collimated laser) is used to directly illuminate the transmission film, and the power of the light source is kept unchanged. The light source is controlled to rotate at a preset angle (such as 1°), and the second grayscale image corresponding to each light source angle is sequentially photographed during the rotation process until the light spot projected by the light source reaches the maximum field of view of the camera. Then, the second power value corresponding to each second grayscale image is calculated according to the power corresponding value and the total grayscale value of each second grayscale image, and the camera field of view angle corresponding to each second power value is obtained, which is actually to obtain the camera field of view angle corresponding to each light source angle, so that the normalized change function of the grayscale value and the camera field of view angle can be constructed according to all the second power values ​​and the camera field of view angle. The normalized change function reflects the mapping relationship between the grayscale value data of the grayscale image and the camera field of view angle under different light source angles and shooting field of view angles. Finally, the inverse of the normalized change function can be taken to supplement the field of view attenuation and the grayscale value attenuation caused by the oblique incident light beam, thereby correcting the grayscale value of the grayscale image. It should be noted that, the “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 parameters.

[0097] As an example, 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 transmissive film is illuminated in sequence, and the camera is controlled to sequentially capture the second grayscale image corresponding to each light source angle, and 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 , get the camera field of view angle θ corresponding to each second grayscale image: θ1, θ2, θ3, …, θ 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 change function R(θ) can be obtained by fitting according to all the second power values ​​and all the camera field of view angles.

[0098] Example 1

[0099] like Figure 6 As shown, Figure 6 The figure shows a grayscale image of a sub-optical element for projecting a dot matrix light spot provided by an embodiment of the present application. In this embodiment, the sub-optical element is used to project a 5*3 dot matrix light spot. The light beam emitted by a single-point VCSEL (Vertical-Cavity Surface-Emitting Laser) light source is modulated by a wafer-level optical fillet to form a 5*3 dot matrix distribution on the transmission film. After calculation, it can be obtained Figure 6 The power value P of each spot in n , the optical efficiency is calculated as: Wherein, P0 is the first power value corresponding to the light source. In order to make better use of light energy, the optical efficiency η should be as high as possible. Exemplarily, the standard for qualified performance may be that the optical efficiency η is greater than 65%.

[0100] Optionally, another optical performance parameter for evaluating the sub-optical element used to project the dot matrix light spot is the uniformity of the power value of each light spot. Since the power value of each light spot has been obtained, the uniformity of the light spot power value can be calculated. Exemplarily, the calculation method of the uniformity of one light spot power value is: Among them, ε is the uniformity of the spot power value, P max is the power value of the strongest light spot, P min is the power value of the weakest spot. When the power of each spot is more uniform, P max and P min The closer the uniformity ε is, the closer it is to 100%, that is, the higher the uniformity is, the better the performance of the sub-optical element is. Exemplarily, the standard for qualified performance may be that the uniformity ε is greater than 80%.

[0101] Example 2

[0102] like Figure 7 As shown, Figure 7 The figure shows a grayscale image of a sub-optical element for projecting a line light spot provided by an embodiment of the present application. In this embodiment, the sub-optical element is used to project a line light spot, and its function is to disperse the light beam emitted by the light source into a line light spot with a unidirectional large angle divergence. When evaluating the performance of this sub-optical element, the power in the line light spot can be selected to be greater than the maximum power value e -2 The sum of all values ​​of is recorded as the effective value P L , the calculation formula of optical efficiency is: Wherein, P0 is the first power value corresponding to the light source. Exemplarily, the standard of qualified performance may be that the optical efficiency η is greater than 80%.

[0103] Optionally, the optical performance parameters for evaluating line spot performance include line width, line length and uniformity, which can be calculated separately Figure 7 The power value at the longitudinal edge of the middle spot drops to the maximum power value e -2 The angle range at which the light spot is located and the power value at the lateral edge of the spot drops to the maximum power value e -2 The angular range at and the uniformity of the internal power value distribution of the upper edge maximum value of the transverse section of the longitudinal center of the light spot. Since the power value distribution of the light spot has been obtained, the above optical performance parameters can be easily calculated.

[0104] Example 3

[0105] like Figure 8 As shown, Figure 8 FIG. 1 shows a grayscale image of a sub-optical element for light homogenization provided by an embodiment of the present application. In this embodiment, the sub-optical element is used to homogenize the light beam emitted by the light source. Its function is to disperse and homogenize the light beam emitted by the light source into an overall light spot within a specific FOI angle range. Similar to the sub-optical element used to project a line light spot, the FOI is reduced from the edge power of the light spot to the maximum power value e -2 The optical efficiency is determined by the angle range at which the power in the spot is greater than the maximum power value e -2 The sum of all values ​​at P D The ratio of the optical efficiency η to the first power value P0 of the light source. Exemplarily, the qualified performance standard may be that the optical efficiency η is greater than 80%.

[0106] Example 4

[0107] like Fig. 9 As shown, Fig. 9 FIG. 1 shows a grayscale image of a sub-optical element for collimation provided by an embodiment of the present application. In this embodiment, the sub-optical element is used to collimate the light beam emitted by the light source, and its function is to collimate the divergent light beam of the light source into a collimated light beam. The optical efficiency of this sub-optical element is determined by the power in the spot being greater than the maximum power value e -2 The sum of all values ​​of P CThe ratio of the optical efficiency η to the first power value P0 of the light source. Exemplarily, the qualified performance standard may be that the optical efficiency η is greater than 80%.

[0108] In addition, an important optical performance parameter for measuring the sub-optical element used for collimation is the collimation degree. After the optical power calibration, the standard product calibration has been carried out. During the inspection process, the spot power distribution of the sub-optical element to be tested is subtracted from the spot power distribution of the standard product. If the sum of the total difference is less than the preset threshold of the sum of the spot power 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%.

[0109] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A wafer-level detection device, characterized in that: The wafer-level detection device comprises: a light source, a carrying module, a transmission film and a camera; The light source and the camera are respectively arranged on two sides of the transmissive film; The light source is used to emit a light beam to the 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 carrying module is used to carry and fix the wafer to be inspected, and the carrying module is configured to be movable relative to the light source, 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 photograph the light field distribution on the transmission film, and the photographed 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 detection device according to claim 1, characterized in that: The area of ​​the transmission film is larger than the coverage range of the light field distribution.

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

4. The wafer-level detection device according to claim 1, characterized in that: The difference between the transmittances at various locations on the transmittance film is within a preset range.

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

6. The wafer-level inspection device according to claim 1, characterized in that: A 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 spacing between the light source and the sub-optical element currently being inspected on the wafer to be inspected and the working spacing of the sub-optical element currently being inspected is within a preset tolerance range.

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

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

10. A wafer-level detection method based on the wafer-level detection device according to any one of claims 1 to 9, characterized in that: The wafer-level detection method comprises: Performing optical power calibration based on the light source, the transmissive film and the camera to obtain a power corresponding value, wherein the power corresponding value represents a conversion mapping relationship between a grayscale value and an optical power value; Based on the power corresponding value, a calculation is performed according to the grayscale image of the currently detected sub-optical element to obtain a power value distribution corresponding to the currently detected sub-optical element; According to the power value distribution of the currently detected sub-optical element, the optical performance parameter corresponding to the currently detected sub-optical element is calculated.

11. The wafer-level detection method according to claim 10, characterized in that: The wafer-level detection method further includes: constructing a normalized variation function based on the light source, the transmission film and the camera, wherein the normalized variation function represents a mapping relationship between the grayscale value and the camera field of view angle of the camera; First, based on the normalized variation function, image data correction is performed on the grayscale image of the currently detected sub-optical element, and then based on the power corresponding value, calculation is performed according to the grayscale image of the currently detected sub-optical element to obtain the power value distribution corresponding to the currently detected sub-optical element.

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