Wafer-based detection focusing method, device, equipment and product

Abstract

The application discloses a wafer detection-based focusing method, device, equipment and product, relates to the technical field of semiconductor wafer detection, and the method comprises the following steps: when it is detected that a to-be-detected wafer reaches an imaging position, emitting a point laser to the to-be-detected wafer through a test light path built in advance to obtain an imaging light beam; collecting a light spot image corresponding to the imaging light beam through a double-imaging camera, and calculating a light spot area through the light spot image; calculating an out-of-focus amount of the to-be-detected wafer according to the light spot area, moving the to-be-detected wafer for focusing according to the out-of-focus amount, and obtaining a focusing result. Therefore, the problem that the existing focusing mode needs to be repeatedly scanned, thereby being low in efficiency and failing to meet the requirement of accurate and rapid focusing of wafer microlenses is solved, and the efficiency of wafer detection-based focusing is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor wafer inspection technology, and in particular to a focusing method, apparatus, equipment and product based on wafer inspection. Background Technology

[0002] Wafer microlenses are tiny lenses ranging from hundreds of nanometers to several millimeters in diameter. They are often arranged in arrays on a substrate and have functions such as focusing, imaging, beam shaping, and light splitting. With their advantages of miniaturization and high integration, they play a key role in the miniaturization, intelligentization, and integration of optoelectronic devices and optical systems. An eight-inch wafer can be photolithographically etched with 40,000 to 60,000 microlenses. Inspection requires efficient and accurate focusing. The current mainstream image focusing solutions include contrast detection autofocus (CDAF) and phase detection autofocus (PDAF). The former determines the focus by calculating the contrast of adjacent pixels, while the latter relies on the phase difference of pixels to quickly measure the focus. Both are commonly used methods for focusing in industrial vision.

[0003] However, existing focusing solutions have significant drawbacks. They rely on images with clear boundaries and high contrast, and require the driving mechanism to repeatedly move and scan along the Z-axis to determine the focus. This is time-consuming and inefficient. In microlens inspection scenarios, images have no obvious features, and traditional solutions cannot be adapted. As a result, the inspection of an entire wafer takes three to seven days, which seriously restricts the production efficiency of enterprises and makes it difficult to meet the needs of modern industry for rapid and accurate microlens inspection.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this application is to provide a focusing method, apparatus, device, and product based on wafer inspection, which aims to solve the technical problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses.

[0006] To achieve the above objectives, this application proposes a focusing method based on wafer inspection, wherein the focusing method based on wafer inspection includes: When the wafer under test is detected to have reached the imaging position, a point laser is emitted toward the wafer under test through a pre-built test optical path to obtain an imaging beam; The light spot image corresponding to the imaging beam is acquired by dual imaging cameras, and the light spot area is calculated from the light spot image. The defocusing amount of the wafer under test is calculated based on the area of ​​the light spot, and the wafer under test is moved and refocused according to the defocusing amount to obtain the focusing result.

[0007] In one embodiment, before the step of emitting a point laser beam onto the wafer under test through a pre-built test optical path to obtain an imaging beam when the wafer under test is detected to have reached the imaging position, the method further includes: Select a point laser with an independent wavelength and configure the point laser in a parallel incident mode; According to the parallel incidence mode, the reflected laser corresponding to the point laser is split into a transmitted beam and a reflected beam by a beam splitter. A camera in focus is configured with the focal plane position based on the transmitted beam, and a camera out of focus is configured with the defocus position based on the reflected beam. A dual-imaging camera is formed by the in-focus camera and the out-of-focus camera, and a filter is configured for the dual-imaging camera; The effective area of ​​the test spot image acquired by the dual imaging camera is cropped to obtain the effective area of ​​the spot; The test optical path is constructed by integrating the transmitted beam, reflected beam, dual imaging camera, and effective area of ​​the light spot.

[0008] In one embodiment, the step of emitting a laser beam at a point on the wafer under test through a pre-built test optical path to obtain an imaging beam includes: The test optical path outputs point lasers of independent wavelengths to the wafer under test; The point laser is incident as a parallel beam onto the wafer under test to obtain reflected laser light; The reflected laser beam is split by the beam splitting element to obtain a transmitted beam and a reflected beam; The transmitted beam and the reflected beam together form an imaging beam.

[0009] In one embodiment, the step of acquiring a spot image corresponding to the imaging beam using dual imaging cameras and calculating the spot area using the spot image includes: The dual imaging cameras acquire a first spot image corresponding to the transmitted beam and a second spot image corresponding to the reflected beam. Threshold segmentation is performed on the first spot image and the second spot image respectively to obtain the first spot region and the second spot region within a preset gray range; Morphological opening and morphological closing operations are performed on the first spot region and the second spot region, respectively. After the morphological opening and closing operations are completed, the first spot region and the second spot region are filtered to obtain connected regions that meet the area threshold. Extract the target spot region from the connected domain and fill the internal voids in the target spot region; After the filling is completed, the number of pixels in the target spot area is calculated to obtain the spot area.

[0010] In one embodiment, before the step of calculating the defocus amount of the wafer under test based on the spot area, the method further includes: The wafer under test is controlled by the Z-axis controller to move the focal position in the spot image of the light spot, and the moving spot image is acquired by the dual imaging camera during the movement. Calculate the area of ​​the moving spot in the moving spot image, whereby the area of ​​the moving spot includes the area of ​​the moving spot from the in-focus camera and the area of ​​the moving spot from the out-of-focus camera. By fitting the Z-axis position parameters of the Z-axis controller to the light spot area of ​​the moving in-focus camera, a quadratic polynomial curve of the light spot area of ​​the moving in-focus camera versus the Z-axis position parameters is obtained. By fitting the Z-axis position parameters of the Z-axis controller to the light spot area of ​​the moving defocus camera, a linear polynomial relationship between the light spot area of ​​the moving defocus camera and the Z-axis position parameters is obtained.

[0011] In one embodiment, the spot area includes the spot area of ​​the defocus camera and the spot area of ​​the in-focus camera, and the step of calculating the defocus amount of the wafer under test based on the spot area includes: The first position parameter is obtained by calculating the spot area of ​​the in-focus camera using the quadratic polynomial curve. The second position parameter is obtained by calculating the area of ​​the defocused camera spot using the first-order polynomial straight line. Determine the optimal focus position based on the first position parameter and the second position parameter; The difference between the actual Z-axis position of the wafer under test and the optimal focusing position is calculated to obtain the defocusing amount of the wafer under test.

[0012] In one embodiment, the step of moving the wafer under test to focus based on the defocus amount to obtain a focusing result includes: Determine whether the defocus amount is within the focus accuracy threshold range; If the defocus amount is not within the focus accuracy threshold range, the wafer to be tested is moved by the wafer movement controller according to the defocus amount until the defocus amount of the wafer to be tested is within the focus accuracy threshold range. If the defocus amount is within the focus accuracy threshold range, the focus result is "focusing complete".

[0013] Furthermore, to achieve the above objectives, this application also proposes a focusing device based on wafer inspection, the focusing device based on wafer inspection comprising: The emission module is used to emit a laser beam to the wafer under test through a pre-built test optical path when the wafer under test is detected to have reached the imaging position, so as to obtain an imaging beam. The calculation module is used to acquire the spot image corresponding to the imaging beam through dual imaging cameras, and calculate the spot area through the spot image; The focusing module is used to calculate the defocus amount of the wafer under test based on the spot area, and to move the wafer under test to focus based on the defocus amount to obtain the focusing result.

[0014] Furthermore, to achieve the above objectives, this application also proposes a focusing device based on wafer inspection, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the focusing method based on wafer inspection as described above.

[0015] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the focusing method based on wafer inspection as described above.

[0016] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the focusing method based on wafer inspection as described above.

[0017] One or more technical solutions proposed in this application have at least the following technical effects: This application proposes a focusing method, apparatus, device, and product based on wafer inspection. When the wafer under test is detected to have reached the imaging position, a point laser is emitted onto the wafer through a pre-built test optical path to obtain an imaging beam. A dual-imaging camera captures the spot image corresponding to the imaging beam, and the spot area is calculated from the spot image. The defocusing amount of the wafer under test is calculated based on the spot area, and the wafer is moved to focus based on the defocusing amount to obtain the focusing result. Thus, a dedicated test optical path is built to emit a point laser to form an imaging beam. Dual-imaging cameras capture spot images and calculate the spot area, directly converting the defocusing amount to the spot area. This eliminates the need for repeated scanning along the Z-axis for focusing, quickly obtaining the wafer microlens position offset, and directly driving the wafer to move and complete focusing. This avoids the time-consuming repeated scanning defects of traditional solutions, achieving precise and efficient focusing of the microlens. It solves the problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses, thereby improving the efficiency of focusing based on wafer inspection. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of a focusing method based on wafer inspection provided in Embodiment 1 of this application; Figure 2 This is a flowchart illustrating Embodiment 2 of the focusing method based on wafer inspection in this application; Figure 3 This is a schematic diagram illustrating the change of the spot area with the Z-axis in the focusing method based on wafer inspection in this application; Figure 4 This is a schematic diagram illustrating the relationship between the spot area and the Z-axis position in the focusing method based on wafer inspection in this application; Figure 5 This is a simplified flowchart of the focusing method based on wafer inspection provided in Embodiment 2 of this application; Figure 6 This is a schematic diagram of the module structure of the focusing device based on wafer inspection according to an embodiment of this application; Figure 7 This is a schematic diagram of the hardware operating environment involved in the focusing method based on wafer inspection in the embodiments of this application.

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0024] The main solution of this application embodiment is as follows: A point laser of an independent wavelength is selected and configured in a parallel incidence mode; according to the parallel incidence mode, the reflected laser corresponding to the point laser is split into a transmitted beam and a reflected beam using a beam splitter; a focus camera is configured at the focal plane position based on the transmitted beam, and a defocus camera is configured at the defocus position based on the reflected beam; a dual imaging camera is formed by the focus camera and the defocus camera, and a filter is configured for the dual imaging camera; the effective area of ​​the test spot image acquired by the dual imaging camera is cropped to obtain an effective spot area; a test optical path is constructed by integrating the transmitted beam, the reflected beam, the dual imaging camera, and the effective spot area. An independent wavelength point laser is output to the wafer under test through the test optical path; the point laser is incident on the wafer under test as a parallel beam to obtain a reflected laser; the reflected laser is split into a transmitted beam and a reflected beam using the beam splitter; and an imaging beam is formed by the transmitted beam and the reflected beam. The dual imaging cameras acquire a first spot image corresponding to the transmitted beam and a second spot image corresponding to the reflected beam. Threshold segmentation is performed on the first and second spot images to obtain a first spot region and a second spot region within a preset grayscale range. Morphological opening and closing operations are performed on the first and second spot regions. After the morphological opening and closing operations are completed, region filtering is performed on the first and second spot regions to obtain connected regions that meet an area threshold. A target spot region is extracted from the connected regions, and internal holes in the target spot region are filled. After filling, the number of pixels in the target spot region is calculated to obtain the spot area. The wafer under test is controlled by a Z-axis controller to move along the Z-axis coordinate of the focal position in the spot image, and the moving spot image is acquired by the dual imaging cameras during the movement. The moving spot area of ​​the moving spot image is calculated, and the moving spot area includes the spot area of ​​the moving in-focus camera and the spot area of ​​the moving out-of-focus camera. The Z-axis position parameters corresponding to the Z-axis controller are fitted with the spot area of ​​the moving in-focus camera to obtain a quadratic polynomial curve of the spot area of ​​the moving in-focus camera and the Z-axis position parameters. The Z-axis position parameters corresponding to the Z-axis controller are fitted with the spot area of ​​the moving out-of-focus camera to obtain a linear polynomial curve of the spot area of ​​the moving out-of-focus camera and the Z-axis position parameters. The first position parameter is obtained by calculating the spot area of ​​the in-focus camera using the quadratic polynomial curve; the second position parameter is obtained by calculating the spot area of ​​the defocus camera using the first polynomial straight line; the optimal focus position is determined based on the first and second position parameters; the defocus amount of the wafer under test is obtained by calculating the difference between the actual Z-axis position of the wafer under test and the optimal focus position.The system determines whether the defocus amount is within the focusing accuracy threshold range. If the defocus amount is not within the threshold range, the wafer under test is moved by a wafer movement controller until the defocus amount falls within the threshold range. If the defocus amount is within the threshold range, the focusing result is considered complete. This solves the problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses. It achieves wafer-based focusing, improving focusing efficiency. Based on the present invention, this invention addresses the problem that existing focusing methods rely on images with clear boundaries and high contrast, requiring repeated scanning along the Z-axis by a driving mechanism to determine the focus, which is time-consuming and inefficient. Furthermore, in microlens inspection scenarios, images lack obvious features, making traditional methods unsuitable and resulting in wafer inspection taking three to seven days, thus leading to low efficiency. Therefore, this invention proposes a wafer inspection-based focusing method. The effectiveness of this method was verified during wafer focusing, and the efficiency of wafer inspection-based focusing was significantly improved using the present invention.

[0025] In this embodiment, for ease of description, the following description uses a focusing device based on wafer inspection as the main execution subject.

[0026] Due to the limitations of mainstream industrial vision focusing solutions in existing technologies, the focusing efficiency of wafer microlens inspection still needs to be improved. One issue is the adaptability of image features. Traditional CDAF and PDAF focus rely on clear boundaries and high-contrast image features. Microlens inspection images lack obvious features, which can easily lead to focusing failure. Another issue is the efficiency of focusing and scanning. Existing solutions require repeated scanning along the Z-axis to determine the focus, which is time-consuming. There is also the issue of efficiency in large-scale inspection. The number of microlenses on a single wafer is huge, and traditional focusing methods are difficult to adapt to the needs of batch inspection. Therefore, in the wafer microlens inspection scenario, efficient and accurate focusing is also a challenge. Existing solutions cannot achieve fast focusing, which seriously restricts the production efficiency of batch inspection of wafer microlenses.

[0027] This application provides a solution that constructs a dedicated test optical path, uses lasers at the emission point to form an imaging beam, employs dual imaging cameras to acquire light spot images and calculates the light spot area, and directly converts the defocusing amount through the light spot area. This eliminates the need for repeated scanning along the Z-axis for focusing, and can quickly obtain the positional offset of the wafer microlens, directly driving the wafer to move and complete focusing. This avoids the time-consuming defects of repeated scanning in traditional solutions, achieving precise and efficient focusing of the microlens. It solves the problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses, thus improving the focusing efficiency based on wafer inspection.

[0028] Based on this, embodiments of this application provide a focusing method based on wafer inspection, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the focusing method based on wafer inspection in this application.

[0029] In this embodiment, the focusing method based on wafer inspection includes steps S01 to S03: Step S01: When the wafer under test is detected to have reached the imaging position, a point laser is emitted to the wafer under test through a pre-built test optical path to obtain an imaging beam. Before the present embodiment begins to describe the solution, it should be clear that in the prior art, the focusing solution relies on the image having clear boundaries and high contrast features, and the driving mechanism needs to move and scan repeatedly along the Z-axis to determine the focus. This is time-consuming and inefficient. However, in the microlens detection scenario, the image has no obvious features, and the traditional solution cannot be adapted. As a result, the detection of the entire wafer takes three to seven days, which seriously restricts the production efficiency of enterprises and makes it difficult to meet the needs of modern industry for rapid and accurate detection of microlenses.

[0030] Therefore, in order to solve the above problems, this embodiment activates the pre-built test optical path after detecting that the wafer under test has reached the preset imaging position. The point laser source in the optical path is controlled to emit point lasers of independent wavelengths. The point lasers are calibrated into parallel beams by the lenses in the optical path and are incident perpendicularly on the surface of the wafer under test. After being reflected by the wafer microlens, they form reflected lasers. After being split by the beam splitting element, the reflected lasers form a transmitted beam and a reflected beam for subsequent imaging. The two together constitute the imaging beam.

[0031] Step S02: Acquire the spot image corresponding to the imaging beam using dual imaging cameras, and calculate the spot area using the spot image; At this time, the in-focus camera and the out-of-focus camera in the dual imaging camera are started simultaneously, respectively acquiring the light spot images corresponding to the transmitted beam and the reflected beam. A series of image processing operations such as threshold segmentation, morphological processing, and region filtering are performed on the acquired two light spot images to remove image noise, fill light spot holes, and filter out effective target light spot areas. Finally, the area of ​​each of the two light spots is obtained by calculating the number of pixels in the target light spot area.

[0032] Step S03: Calculate the defocus amount of the wafer under test based on the spot area, and move the wafer under test to refocus based on the defocus amount to obtain the refocusing result.

[0033] Finally, the calculated areas of the two light spots are substituted into the pre-fitted quadratic polynomial curve and linear polynomial line, respectively, to solve for the current Z-axis position and the optimal Z-axis position of the wafer under test. The difference between the two is calculated to obtain the defocus amount. It is then determined whether the defocus amount is within the preset focusing accuracy range. If not, the Z-axis displacement mechanism is controlled to move the wafer under test along the Z-axis until the defocus amount meets the accuracy requirements, thus completing the focusing and outputting the focusing result.

[0034] In summary, this embodiment uses point lasers and a dual imaging system to directly calculate the defocus amount using the spot area, eliminating the need for repeated scanning and focusing along the Z-axis. This saves the time-consuming process of multiple movements, imaging, and calculations required by traditional methods. Furthermore, this embodiment does not rely on wafer surface textures or high-contrast features, making it suitable for detection scenarios with weak features and no obvious boundaries, such as microlenses. It can still achieve fast focusing response and high accuracy, significantly reducing the whole wafer inspection time from three to seven days and significantly improving production efficiency.

[0035] Specifically, before step S01 above, which involves emitting a point laser beam onto the wafer under test through a pre-built test optical path to obtain an imaging beam when the wafer under test is detected to have reached the imaging position, the method further includes: Step S0101: Select a point laser with an independent wavelength and configure the point laser in parallel incident mode; Step S0102: According to the parallel incident mode, the reflected laser corresponding to the point laser is split into a transmitted beam and a reflected beam by a beam splitting element. Step S0103: Configure an in-focus camera at the focal plane position based on the transmitted beam, and configure an out-of-focus camera at the defocus position based on the reflected beam. Step S0104: A dual imaging camera is formed by the in-focus camera and the out-of-focus camera, and a filter is configured for the dual imaging camera. Step S0105: The effective area of ​​the test spot image acquired by the dual imaging camera is cropped to obtain the effective area of ​​the spot; Step S0106: The test optical path is constructed by integrating the transmitted beam, the reflected beam, the dual imaging camera, and the effective area of ​​the light spot.

[0036] First, a point laser with a wavelength significantly different from other light sources in the system is selected to avoid interference between different light sources and ensure the clarity of the light spot imaging. The selected point laser is calibrated by the lens assembly in the optical path and configured as a parallel incident mode to ensure that the laser can be incident perpendicularly and uniformly onto the surface of the wafer under test.

[0037] Subsequently, based on the parallel incident mode of the point laser, a beam splitter cube was selected as the beam splitting element. The angle and position of the beam splitting element were pre-adjusted so that the reflected laser after the point laser is reflected by the wafer under test can be accurately split into two beams, forming a downward transmitted beam and a right-reflected beam. The two beams do not interfere with each other and the light intensity is stable.

[0038] Based on the propagation path of the transmitted light beam, the sensor target surface of the focusing camera is precisely aligned at the rear focal point of the tube lens to ensure that the focusing camera can acquire the clearest light spot image. At the same time, based on the propagation path of the reflected light beam, the sensor target surface of the defocusing camera is set at a slightly defocused position at the rear focal point of the tube lens to form a preset defocus distance, which facilitates the subsequent calculation of the defocus amount.

[0039] The in-focus and out-of-focus cameras, which have been debugged, are combined to form a dual-imaging camera. Filters matching the wavelength of the point laser are installed in front of the lenses of both cameras to filter out ambient light, stray light and other interfering light, thereby further improving the imaging quality of the spot image.

[0040] The system controls dual imaging cameras to acquire a set of test spot images. Using ROI cropping technology, invalid background areas in the images are cropped according to the actual size and shape of the test spots, leaving only the spot imaging area. This reduces the amount of imaging data, significantly reduces the real-time calculation time in the later stages, and improves the camera's acquisition frame rate and real-time defocus sampling rate.

[0041] Finally, the transmitted and reflected beam propagation paths, after being debugged, are combined with dual imaging cameras equipped with filters and with effective area cropping settings, and integrated and debugged as a whole to ensure that all components work together, the optical path propagates smoothly, and the imaging is stable. The test optical path is then built to prepare for subsequent focus testing.

[0042] More specifically, step S01 above, which involves emitting a laser beam at a point on the wafer under test through a pre-built test optical path to obtain an imaging beam, includes: Step S011: Output point lasers of independent wavelengths to the wafer under test through the test optical path; Step S012: The point laser is incident on the wafer under test as a parallel beam to obtain reflected laser; Step S013: The reflected laser beam is split by the beam splitting element to obtain a transmitted beam and a reflected beam; Step S014: The transmitted beam and the reflected beam are combined to form an imaging beam.

[0043] The point laser source in the test optical path is activated, and the source emits a point laser with a preset independent wavelength. The point laser is further calibrated by the lens assembly in the optical path to ensure that the laser intensity is uniform and the beam parallelism meets the preset standard. Then, the point laser is output to the wafer under test at the preset imaging position through the optical path.

[0044] The output point laser is incident perpendicularly to the surface of the wafer under test in the form of a parallel beam. After being reflected by the microlens on the wafer, the beam forms a reflected laser. The propagation direction of the reflected laser is opposite to that of the incident direction, and it returns to the beam splitter along the original optical path.

[0045] The pre-calibrated beam splitter precisely splits the reflected laser into two paths: one path transmits downwards along the original direction to form a transmitted beam, and the other path reflects to the right to form a reflected beam. The intensity ratio of the two beams meets the preset requirements, and both maintain good parallelism.

[0046] The transmitted and reflected beams obtained by beam splitting are integrated to ensure that the two beams can be accurately incident on the corresponding lenses of the dual imaging cameras. The two beams work together to form the imaging beam used for subsequent spot acquisition and defocus calculation. The intensity of the imaging beam is stable and there is no obvious interference.

[0047] Further, step S02 above, which involves acquiring a spot image corresponding to the imaging beam using dual imaging cameras and calculating the spot area using the spot image, includes: Step S021: The dual imaging camera acquires the first spot image corresponding to the transmitted beam and the second spot image corresponding to the reflected beam. Step S022: Threshold segmentation is performed on the first spot image and the second spot image respectively to obtain the first spot region and the second spot region within a preset gray range; Step S023: Perform morphological opening and morphological closing operations on the first spot region and the second spot region, respectively. Step S024: After the morphological opening and morphological closing operations are completed, the first spot region and the second spot region are filtered to obtain connected regions that meet the area threshold. Step S025: Extract the target spot region from the connected domain and fill the internal voids in the target spot region; Step S026: After the filling is completed, calculate the number of pixels in the target spot area to obtain the spot area.

[0048] The dual imaging cameras are controlled to start the acquisition function synchronously. The in-focus camera acquires the first spot image corresponding to the transmitted beam, and the out-of-focus camera acquires the second spot image corresponding to the reflected beam. During the acquisition process, the camera frame rate is kept consistent to ensure that the acquisition time of the two spot images is synchronized, and to avoid calculation errors caused by acquisition time difference.

[0049] Threshold segmentation is performed on the first and second spot images acquired respectively. The preset gray value range is 30 to 255. The pixel areas in the image with gray values ​​within this range are extracted to generate a binarized image, thereby clearly distinguishing the spot area from the background area and removing dark background noise and stray light interference. The gray value range can be flexibly adjusted according to the actual laser intensity.

[0050] For the first and second spot regions obtained by threshold segmentation, morphological opening and morphological closing operations are performed sequentially. A circular structuring element with a radius of 3 is selected. The morphological opening operation first erodes and then dilates the spot region to remove small bright spots and subtle noise in the spot region. The morphological closing operation first dilates and then erodes to smooth the edge of the spot region, fill in small holes at the edge of the spot, and further improve the integrity of the spot region.

[0051] After morphological processing, connected component analysis is performed on the first and second spot regions respectively. The continuous pixels in each region are connected into multiple connected regions. Then, an area threshold of 70 is set to filter out connected regions whose area meets the threshold, and invalid regions that are too small or too large are filtered out to ensure the accuracy of subsequent calculations.

[0052] From the selected connected regions, the target spot region with the closest shape to a circle and the most complete edge is extracted. To address the problem of insufficient brightness in the center caused by the divergence of the spot far from focus, the internal void of the target spot region is filled to make the target spot region a complete solid region, thus avoiding the void affecting the calculation result of the spot area.

[0053] After the filling is completed, the number of pixels in the target spot area is counted by the image pixel counting algorithm. The number of pixels is used as a quantitative indicator of the spot area. The spot areas corresponding to the first spot area and the second spot area are calculated and stored in preset variables to provide data support for subsequent defocus calculation.

[0054] This embodiment, through the above-described scheme, specifically involves emitting a point laser beam onto the wafer under test via a pre-built test optical path when the wafer under test is detected to have reached the imaging position, thereby obtaining an imaging beam. A dual-imaging camera then captures the spot image corresponding to the imaging beam, and the spot area is calculated from the spot image. The defocusing amount of the wafer under test is calculated based on the spot area, and the wafer is moved and refocused based on the defocusing amount to obtain the focusing result. Thus, by constructing a dedicated test optical path to emit a point laser beam to form an imaging beam, using dual-imaging cameras to capture spot images and calculate the spot area, and directly converting the defocusing amount from the spot area, the wafer microlens position offset can be quickly obtained without repeated scanning along the Z-axis for focusing. This directly drives the wafer to move and complete the focusing process, avoiding the time-consuming repeated scanning defects of traditional schemes. This achieves precise and efficient focusing of the microlens, solving the problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses, thereby improving the focusing efficiency based on wafer inspection.

[0055] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 2 Before step S03, which involves calculating the defocus amount of the wafer under test based on the spot area, the focusing method based on wafer inspection further includes steps S0301~S0304: Step S0301: The wafer under test is controlled by the Z-axis controller to move the focal position in the spot image by the Z-axis coordinate, and the moving spot image is acquired by the dual imaging camera during the movement. Step S0302: Calculate the moving spot area of ​​the moving spot image, wherein the moving spot area includes the moving spot area of ​​the in-focus camera and the moving spot area of ​​the out-of-focus camera. Step S0303: Fit the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving in-focus camera to obtain a quadratic polynomial curve of the light spot area of ​​the moving in-focus camera and the Z-axis position parameters. Step S0304: Fit the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving defocus camera to obtain a linear polynomial between the light spot area of ​​the moving defocus camera and the Z-axis position parameters.

[0056] like Figure 3As shown, three data lists are first created: the focus area list, the defocus area square root list, and the Z-axis position list. The focus area list is used to record the area of ​​the moving camera spot corresponding to each Z-axis position. The defocus area square root list is used to record the square root value of the area of ​​the moving camera spot corresponding to each Z-axis position. The Z-axis position list is used to record the actual Z-axis coordinates when acquiring data.

[0057] Subsequently, the displacement mechanism carrying the wafer under test is controlled by the Z-axis controller, which moves the wafer under test along the Z-axis direction perpendicular to the wafer surface near the focal point of the point laser. First, the Z-axis is moved to the point where the spot of the focusing camera is the smallest, and the absolute position of the current Z-axis is obtained as the reference point. The Z-axis rapid movement parameters are set, and the Z-axis is moved to the starting position that is offset a certain distance in the positive direction from the reference point. Then, the slower movement parameters are reset to prepare for fine scanning.

[0058] Starting from the starting position, the Z-axis is controlled to move gradually in the negative direction according to a predetermined step size, covering the entire range from the positive offset to the negative offset from the reference point. After each movement, a 15-millisecond pause is made to wait for the mechanical vibration to decay and the image to stabilize. Then, the dual imaging cameras are controlled to synchronously acquire images of the moving light spot during the movement, ensuring that each Z-axis position corresponds to a complete set of moving light spot images.

[0059] For each set of moving light spot images acquired, the light spot area of ​​the moving in-focus camera and the light spot area of ​​the moving out-of-focus camera are calculated respectively. The light spot area of ​​the moving in-focus camera is recorded in the focus area list, and the square root of the light spot area of ​​the moving out-of-focus camera is calculated and recorded in the square root of the out-of-focus area list. At the same time, the actual Z-axis position parameters output by the current Z-axis controller are recorded in the Z-axis position list.

[0060] After all Z-axis positions have been scanned, the data in the three lists are converted into array format and subjected to mathematical fitting, such as... Figure 3 As shown, with the Z-axis position parameter as the independent variable (X) and the area of ​​the moving, focused camera spot as the dependent variable (Y), a quadratic polynomial is used for fitting, resulting in a quadratic polynomial curve between the area of ​​the moving, focused camera spot and the Z-axis position parameter, as shown below. Figure 3 The blue line segment (parabolic model) in the diagram represents the optimal focus position. Using the square root of the area of ​​the light spot from the moving defocusing camera as the independent variable (X) and the Z-axis position parameter as the dependent variable (Y), a first-order polynomial is used for fitting, resulting in a linear first-order polynomial between the light spot area of ​​the moving defocusing camera and the Z-axis position parameter, as shown below. Figure 3 The red line segment in the figure, after the fitting is completed, the two curves are saved for subsequent calculation of defocus amount.

[0061] Specifically, the aforementioned spot area includes the spot area of ​​the defocus camera and the spot area of ​​the in-focus camera. Step S03, which calculates the defocus amount of the wafer under test based on the spot area, includes: Step S031: Calculate the spot area of ​​the in-focus camera using the quadratic polynomial curve to obtain the first position parameter; Step S032: Calculate the area of ​​the defocused camera spot using the first-order polynomial straight line to obtain the second position parameter; Step S033: Determine the optimal focus position based on the first position parameter and the second position parameter; Step S034: Calculate the difference between the actual Z-axis position of the wafer under test and the optimal focusing position to obtain the defocusing amount of the wafer under test.

[0062] like Figure 4 As shown, the spot area of ​​the in-focus camera obtained by real-time acquisition and calculation is substituted into the pre-fitted quadratic polynomial curve. The curve has the Z-axis position as the independent variable and the spot area of ​​the in-focus camera as the dependent variable. The corresponding Z-axis position is obtained by solving the curve, which is the first position parameter. This parameter corresponds to the theoretical focus position detected by the in-focus camera.

[0063] Meanwhile, the area of ​​the defocus camera spot obtained by real-time acquisition and calculation is substituted into a pre-fitted first-order polynomial straight line. This straight line takes the square root of the area of ​​the defocus camera spot as the independent variable and the Z-axis position as the dependent variable. First, the square root of the area of ​​the defocus camera spot is calculated, and then the corresponding Z-axis position is obtained by solving the straight line. This is the second position parameter, which corresponds to the current wafer position detected by the defocus camera.

[0064] Combination Figure 4 The intersection and distribution characteristics of the two curves are used to fuse and calibrate the first and second position parameters, eliminate abnormal data, and take the average of the two as the final optimal focus position Z0. This position is the ideal Z-axis position for the wafer under test to achieve accurate focusing.

[0065] The actual Z-axis position Z1 of the wafer under test is obtained by the Z-axis controller. The difference between the actual Z-axis position Z1 and the optimal focus position Z0 is calculated, i.e., ΔZ=Z1-Z0. This difference is the defocus amount of the wafer under test. If the difference is positive, it means that the current position of the wafer is higher than the optimal focus position. If the difference is negative, it means that the current position of the wafer is lower than the optimal focus position. The larger the absolute value of the defocus amount, the farther it is from the optimal focus position.

[0066] More specifically, step S03 above, which involves moving the wafer under test to focus based on the defocusing amount to obtain the focusing result, includes: Step S035: Determine whether the defocus amount is within the focus accuracy threshold range; Step S036: If the defocus amount is not within the focus accuracy threshold range, then according to the defocus amount, the wafer to be tested is moved by the wafer movement controller until the defocus amount of the wafer to be tested is within the focus accuracy threshold range. Step S037: If the defocus amount is within the focus accuracy threshold range, the focus result is "focusing complete".

[0067] A pre-set focusing accuracy threshold is set, which is determined according to the detection requirements of the wafer microlens. It is usually set to the sub-micron level to ensure that the focusing accuracy can meet the precise requirements of microlens detection.

[0068] Based on the defocus amount calculated in the above steps, it is compared with the preset focus accuracy threshold to determine whether the absolute value of the defocus amount is less than or equal to the focus accuracy threshold, thereby determining whether the current wafer is in a precise focus state.

[0069] If the defocus amount is not within the focusing accuracy threshold range, the wafer movement controller controls the Z-axis displacement mechanism to move the wafer under test along the Z-axis direction according to the magnitude of the defocus amount. If the defocus amount is positive, the wafer is controlled to move downward; if the defocus amount is negative, the wafer is controlled to move upward. The distance moved is proportional to the absolute value of the defocus amount. At the same time, spot images during the movement are acquired in real time, the real-time defocus amount is calculated, and the moving speed and distance are dynamically adjusted.

[0070] Repeat the above movement and detection process until the calculated defocus amount is within the preset focusing accuracy threshold range, then stop wafer movement.

[0071] If the defocusing amount is within the focusing accuracy threshold range, it means that the wafer under test has reached the optimal focusing position. At this time, the focusing result is output, and the current Z-axis position is recorded as the reference position for this focusing, which can be quickly called in subsequent inspection processes to improve inspection efficiency. If slight defocusing occurs in subsequent inspection processes, it can be quickly adjusted based on the reference position.

[0072] In this embodiment, the above-described scheme specifically involves using a Z-axis controller to move the wafer under test along the Z-axis at the focal point of the light spot image, and acquiring the moving light spot image using the dual imaging cameras during the movement. The moving light spot area is calculated, including the area of ​​the moving in-focus camera and the area of ​​the moving out-of-focus camera. The Z-axis position parameters corresponding to the Z-axis controller are fitted with the area of ​​the moving in-focus camera to obtain a quadratic polynomial curve relating the moving in-focus camera's light spot area to the Z-axis position parameters. Finally, the Z-axis position parameters corresponding to the Z-axis controller are fitted with the area of ​​the moving out-of-focus camera's light spot area to obtain a linear polynomial relating the moving out-of-focus camera's light spot area to the Z-axis position parameters. Therefore, a dedicated test optical path is constructed to emit a laser beam to form an imaging beam. Dual imaging cameras are used to acquire the light spot image and calculate the light spot area. The defocus amount is directly calculated from the light spot area, eliminating the need for repeated scanning along the Z-axis for focusing. This allows for the rapid acquisition of the wafer microlens position offset, directly driving the wafer to move and complete focusing. This avoids the time-consuming defects of repeated scanning in traditional solutions, achieving precise and efficient focusing of the microlens. It solves the problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses, thus improving the focusing efficiency based on wafer inspection.

[0073] For example, to help understand the implementation flow of the focusing method based on wafer inspection obtained by combining this embodiment with the above embodiment one, please refer to... Figure 5 , Figure 5 A simplified flowchart of a focusing method based on wafer inspection is provided, specifically: First, the test optical path is constructed. A point laser of an independent wavelength is selected and configured as a parallel incident mode. The reflected laser beam is split by a beam splitter. A dual imaging camera is configured with a focusing camera and a defocusing camera and a filter is added. The test spot image acquired by the camera is effectively cropped. All components are integrated to complete the test optical path construction.

[0074] After the optical path is set up, preparations are made for auxiliary focusing. The wafer under test is controlled by the Z-axis controller to scan finely along the Z-axis near the focal point. Simultaneously, images of the moving spot are acquired and the area of ​​the moving spot is calculated. The quadratic polynomial curve and the linear polynomial curve are fitted to complete the calibration and save the curve data.

[0075] Then, the formal focusing and detection is initiated. After the wafer under test is detected to have reached the imaging position, a parallel point laser is emitted to the wafer through the test optical path. After reflection and beam splitting, an imaging beam is formed. The dual imaging cameras simultaneously acquire two beam spot images. After threshold segmentation, morphological processing, region filtering, and hole filling, the area of ​​the two beam spots is calculated.

[0076] Substitute the area of ​​the light spot into the pre-fitted curve to obtain the first position parameter and the second position parameter, determine the optimal focus position, and calculate the defocus amount by calculating the difference between the current Z-axis position and the optimal focus position.

[0077] Determine if the defocus amount is within the focus accuracy threshold range. If not, control the wafer to move along the Z-axis to adjust until the defocus amount meets the requirements, and output the focus completion result. If it is within the threshold range, directly output the focus completion result.

[0078] In addition, it can meet different needs through three usage methods: Method 1 is autofocus tracking, which calculates the defocus amount in real time and adjusts it repeatedly to improve focusing accuracy; Method 2 is out-of-focus shooting, which calculates the defocus amount in real time and provides the distance between the shooting surface and the focal surface for subsequent detection algorithm correction; Method 3 is scanning the surface parameters of the measured object, moving the measured object horizontally and continuously calculating the defocus amount to achieve sub-micron accuracy, which can replace the complex spectral confocal displacement sensor.

[0079] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the focusing method based on wafer inspection in this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0080] This application also provides a focusing device based on wafer inspection, please refer to... Figure 6 The focusing device based on wafer inspection includes: The emission module 10 is used to emit a laser beam to the wafer under test through a pre-built test optical path when the wafer under test is detected to have reached the imaging position, so as to obtain an imaging beam. The calculation module 20 is used to acquire the spot image corresponding to the imaging beam through the dual imaging cameras, and calculate the spot area through the spot image; The focusing module 30 is used to calculate the defocus amount of the wafer under test based on the spot area, and to move and focus the wafer under test according to the defocus amount to obtain a focusing result.

[0081] The wafer inspection-based focusing device provided in this application, employing the wafer inspection-based focusing method described in the above embodiments, solves the technical problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses. Compared with the prior art, the beneficial effects of the wafer inspection-based focusing device provided in this application are the same as those of the wafer inspection-based focusing method provided in the above embodiments, and other technical features in the wafer inspection-based focusing device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0082] This application provides a focusing device based on wafer inspection. The focusing device based on wafer inspection includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the focusing method based on wafer inspection in the above embodiment 1.

[0083] The following is for reference. Figure 7 This document illustrates a schematic diagram of a focusing device based on wafer inspection suitable for implementing embodiments of this application. The focusing device based on wafer inspection in these embodiments may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 7 The wafer inspection-based focusing device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0084] like Figure 7 As shown, the wafer inspection-based focusing device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory 1002 or a program loaded from a storage device 1003 into a random access memory 1004. The random access memory 1004 also stores various programs and data required for the operation of the wafer inspection-based focusing device. The processing unit 1001, the read-only memory 1002, and the random access memory 1004 are interconnected via a bus 1005. An input / output interface 1006 is also connected to the bus. Typically, the following systems can be connected to the input / output interface 1006: input devices 1007 including, for example, a touchscreen, touchpad, keyboard, mouse, image sensor, microphone, accelerometer, gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; storage devices 1003 including, for example, magnetic tape, hard disk, etc.; and communication devices 1009. Communication device 1009 allows the wafer inspection-based focusing device to communicate wirelessly or wiredly with other devices to exchange data. While the figures show wafer inspection-based focusing devices with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0085] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from read-only memory 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0086] The wafer inspection-based focusing device provided in this application, employing the wafer inspection-based focusing method described in the above embodiments, solves the technical problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses. Compared with the prior art, the beneficial effects of the wafer inspection-based focusing device provided in this application are the same as those of the wafer inspection-based focusing method provided in the above embodiments, and other technical features of this wafer inspection-based focusing device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0087] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0088] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0089] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the wafer inspection-based focusing method in the above embodiments.

[0090] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0091] The aforementioned computer-readable storage medium may be included in a wafer-based focusing device; or it may exist independently and not assembled into a wafer-based focusing device.

[0092] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by a wafer inspection-based focusing device, the wafer inspection-based focusing device: upon detecting that the wafer under test has reached the imaging position, emits a point laser beam to the wafer under test through a pre-built test optical path to obtain an imaging beam; acquires a spot image corresponding to the imaging beam using dual imaging cameras, and calculates the spot area using the spot image; calculates the defocus amount of the wafer under test based on the spot area; and moves the wafer under test to focus based on the defocus amount to obtain a focusing result.

[0093] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0094] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0095] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0096] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described wafer inspection-based focusing method. This solves the technical problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the wafer inspection-based focusing method provided in the above embodiments, and will not be repeated here.

[0097] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the focusing method based on wafer inspection as described above.

[0098] The computer program product provided in this application solves the technical problem that existing focusing methods require repeated scanning, resulting in low efficiency and failing to meet the requirements for precise and rapid focusing of wafer microlenses. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the wafer inspection-based focusing method provided in the above embodiments, and will not be repeated here.

[0099] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A focusing method based on wafer inspection, characterized in that, The focusing method based on wafer inspection includes: When the wafer under test is detected to have reached the imaging position, a point laser is emitted toward the wafer under test through a pre-built test optical path to obtain an imaging beam; The light spot image corresponding to the imaging beam is acquired by dual imaging cameras, and the light spot area is calculated from the light spot image. The defocusing amount of the wafer under test is calculated based on the area of ​​the light spot, and the wafer under test is moved and refocused based on the defocusing amount to obtain the focusing result. Prior to the step of calculating the defocus amount of the wafer under test based on the spot area, the method further includes: The wafer under test is controlled by a Z-axis controller to move along the Z-axis coordinate of the focal position in the spot image, and the moving spot image is acquired by the dual imaging camera during the movement. Calculate the area of ​​the moving spot in the moving spot image, whereby the area of ​​the moving spot includes the area of ​​the moving spot from the in-focus camera and the area of ​​the moving spot from the out-of-focus camera. By fitting the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving focused camera, a quadratic polynomial curve of the light spot area of ​​the moving focused camera versus the Z-axis position parameters is obtained. By fitting the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving defocus camera, a linear polynomial of the light spot area of ​​the moving defocus camera and the Z-axis position parameters is obtained. The spot area includes the spot area of ​​the defocus camera and the spot area of ​​the in-focus camera. The step of calculating the defocus amount of the wafer under test based on the spot area includes: The first position parameter is obtained by calculating the spot area of ​​the in-focus camera using the quadratic polynomial curve. The second position parameter is obtained by calculating the area of ​​the defocused camera spot using the first-order polynomial straight line. Determine the optimal focus position based on the first position parameter and the second position parameter; The difference between the actual Z-axis position of the wafer under test and the optimal focusing position is calculated to obtain the defocusing amount of the wafer under test.

2. The focusing method based on wafer inspection as described in claim 1, characterized in that, Before the step of emitting a point laser beam onto the wafer under test through a pre-built test optical path to obtain an imaging beam when the wafer under test is detected to have reached the imaging position, the method further includes: Select a point laser with an independent wavelength and configure the point laser in a parallel incident mode; According to the parallel incidence mode, the reflected laser corresponding to the point laser is split into a transmitted beam and a reflected beam by a beam splitter. A camera in focus is configured with the focal plane position based on the transmitted beam, and a camera out of focus is configured with the defocus position based on the reflected beam. A dual-imaging camera is formed by the in-focus camera and the out-of-focus camera, and a filter is configured for the dual-imaging camera; The effective area of ​​the test spot image acquired by the dual imaging camera is cropped to obtain the effective area of ​​the spot; The test optical path is constructed by integrating the transmitted beam, reflected beam, dual imaging camera, and effective area of ​​the light spot.

3. The focusing method based on wafer inspection as described in claim 2, characterized in that, The step of emitting laser light at a point on the wafer under test through a pre-built test optical path to obtain an imaging beam includes: The test optical path outputs point lasers of independent wavelengths to the wafer under test; The point laser is incident as a parallel beam onto the wafer under test to obtain reflected laser light; The reflected laser beam is split by the beam splitting element to obtain a transmitted beam and a reflected beam; The transmitted beam and the reflected beam together form an imaging beam.

4. The focusing method based on wafer inspection as described in claim 3, characterized in that, The step of acquiring a spot image corresponding to the imaging beam using dual imaging cameras and calculating the spot area from the spot image includes: The dual imaging cameras acquire a first spot image corresponding to the transmitted beam and a second spot image corresponding to the reflected beam. Threshold segmentation is performed on the first spot image and the second spot image respectively to obtain the first spot region and the second spot region within a preset gray range; Morphological opening and morphological closing operations are performed on the first spot region and the second spot region, respectively. After the morphological opening and closing operations are completed, the first spot region and the second spot region are filtered to obtain connected regions that meet the area threshold. Extract the target spot region from the connected domain and fill the internal voids in the target spot region; After the filling is completed, the number of pixels in the target spot area is calculated to obtain the spot area.

5. The focusing method based on wafer inspection as described in claim 1, characterized in that, The step of moving and focusing the wafer under test according to the defocusing amount to obtain the focusing result includes: Determine whether the defocus amount is within the focus accuracy threshold range; If the defocus amount is not within the focus accuracy threshold range, the wafer to be tested is moved by the wafer movement controller according to the defocus amount until the defocus amount of the wafer to be tested is within the focus accuracy threshold range. If the defocus amount is within the focus accuracy threshold range, the focus result is "focusing complete".

6. A focusing device based on wafer inspection, characterized in that, The focusing device based on wafer inspection includes: The emission module is used to emit a laser beam to the wafer under test through a pre-built test optical path when the wafer under test is detected to have reached the imaging position, so as to obtain an imaging beam. The calculation module is used to acquire the spot image corresponding to the imaging beam through dual imaging cameras, and calculate the spot area through the spot image; The focusing module is used to calculate the defocus amount of the wafer under test based on the spot area, and to move the wafer under test to focus based on the defocus amount to obtain the focusing result. The focusing module is also used to control the focus position of the wafer under test in the spot image to move in the Z-axis coordinate through the Z-axis controller, and to acquire the moving spot image through the dual imaging camera during the movement; Calculate the area of ​​the moving spot in the moving spot image, whereby the area of ​​the moving spot includes the area of ​​the moving spot from the in-focus camera and the area of ​​the moving spot from the out-of-focus camera. By fitting the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving focused camera, a quadratic polynomial curve of the light spot area of ​​the moving focused camera versus the Z-axis position parameters is obtained. By fitting the Z-axis position parameters corresponding to the Z-axis controller to the light spot area of ​​the moving defocus camera, a linear polynomial of the light spot area of ​​the moving defocus camera and the Z-axis position parameters is obtained. The calculation module is also used to include the spot area of ​​the defocus camera and the spot area of ​​the in-focus camera. The focusing module is further configured to calculate the spot area of ​​the in-focus camera using the quadratic polynomial curve to obtain a first position parameter; calculate the spot area of ​​the defocus camera using the first-order polynomial straight line to obtain a second position parameter; determine the optimal focusing position based on the first and second position parameters; and calculate the difference between the actual Z-axis position of the wafer under test and the optimal focusing position to obtain the defocus amount of the wafer under test.

7. A focusing device based on wafer inspection, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the focusing method based on wafer inspection as described in any one of claims 1 to 5.

8. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of the focusing method based on wafer inspection as described in any one of claims 1 to 5.

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