Calibration method and related device

Abstract

The invention discloses a calibration method and a related device. A plurality of temperature values, a current temperature and a plurality of focal plane compensation values are obtained. And if the current temperature reaches a target temperature value in the plurality of temperature values, acquiring a plurality of detection images corresponding to the calibration tool according to the plurality of focal plane compensation values. And determining the focal plane compensation value corresponding to the detection image with the highest definition as a target focal plane compensation value corresponding to the target temperature value according to the definitions corresponding to the multiple detection images. And taking each temperature value as a target temperature value, determining a target focal plane compensation value corresponding to each temperature value, and obtaining a compensation change relation of the target focal plane compensation value along with the temperature value. Therefore, the target focal plane compensation value with a better compensation difference effect corresponding to each temperature value is obtained through calibration, so that the focal plane compensation value can be adjusted according to the compensation change relation adapting to the environment temperature change, the accuracy of the compensation difference is improved, and the focus following capability of the automatic focusing equipment is stronger.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a calibration method and related devices. Background Art

[0002] Depth of field is the distance range along the observation direction within which a clear image of the object under test can be obtained. When inspecting objects such as semiconductor wafers, as the magnification of the objective lens increases, the depth of field gradually decreases, and the difficulty of focusing increases. To obtain a clear image of the object under test, an autofocus device is often used to control the object plane to the imaging focal plane.

[0003] In the related art, due to reasons such as installation errors and chromatic aberration, there may be a difference between the actual focal plane of the autofocus device and the desired imaging focal plane, and the difference is compensated by a preset focal plane compensation value.

[0004] However, autofocus devices are highly sensitive to temperature. When the ambient temperature changes, the focal plane of the autofocus device will drift, that is, the focal plane of the autofocus device will produce floating deviations as the ambient temperature changes. In this case, using the original focal plane compensation value will be difficult to accurately compensate for the difference between the focal plane of the autofocus device and the imaging focal plane, resulting in inaccurate focus and unclear image. Summary of the Invention

[0005] To address the above issues, the present application provides a calibration method and related devices for ensuring that the focal plane compensation value can accurately compensate for the difference between the focal plane of the autofocus device and the imaging focal plane, thereby improving the accuracy of follow focus.

[0006] Based on this, this application discloses the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a calibration method applied to an autofocus device, the method comprising:

[0008] Acquire multiple temperature values, a current temperature, and multiple focal plane compensation values, wherein the current temperature is the temperature of an environment where the autofocus device is located, and the current temperature varies between the multiple temperature values;

[0009] If the current temperature reaches a target temperature value among the multiple temperature values, acquiring multiple detection images corresponding to a calibration tool according to the multiple focal plane compensation values, the calibration tool including a pattern for image calibration;

[0010] According to the sharpnesses respectively corresponding to the plurality of detection images, the focus plane compensation value corresponding to the detection image with the highest sharpness is determined as the target focus plane compensation value corresponding to the target temperature value;

[0011] Taking each of the temperature values as the target temperature value, determining the target focal plane compensation value corresponding to each of the temperature values, and obtaining the compensation change relationship of the target focal plane compensation value with respect to the temperature value.

[0012] Optionally, the method further includes:

[0013] Obtaining a detected temperature, where the detected temperature is the ambient temperature when the autofocus device is used to detect a to-be-detected object;

[0014] Determining the target focal plane compensation value corresponding to the detected temperature according to the compensation change relationship;

[0015] After compensating the autofocus device according to the target focal plane compensation value corresponding to the detected temperature, obtaining a detection image of the to-be-detected object.

[0016] Optionally, the step of determining the target focal plane compensation value corresponding to the target temperature value by using the focal plane compensation value corresponding to the detection image with the highest sharpness among the multiple detection images includes:

[0017] Determining the sharpness scores corresponding to the multiple detection images according to a sharpness algorithm;

[0018] Taking the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

[0019] Optionally, the sharpness algorithm includes a first algorithm and a second algorithm, and the step of determining the sharpness scores corresponding to the multiple detection images according to the sharpness algorithm includes:

[0020] Determining the first sharpness scores corresponding to the multiple detection images according to the first algorithm;

[0021] Determining the second sharpness scores corresponding to the multiple detection images according to the second algorithm;

[0022] The step of taking the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value includes:

[0023] Determining the sharpness scores corresponding to the multiple detection images according to the first sharpness scores and the second sharpness scores corresponding to the multiple detection images;

[0024] Taking the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

[0025] Optionally, determining the focal plane compensation value corresponding to the detection image with the highest sharpness as the target focal plane compensation value corresponding to the target temperature value according to the sharpness corresponding to the multiple detection images respectively includes:

[0026] Determining the image differences between the multiple detection images and a target image respectively;

[0027] Determining the focal plane compensation value corresponding to the detection image with the smallest image difference as the target focal plane compensation value corresponding to the target temperature value, where the target image is an image with sharpness greater than a sharpness threshold.

[0028] Optionally, the multiple focal plane compensation values are the multiple focal plane compensation values included in a compensation traversal range.

[0029] Optionally, the multiple temperature values are the multiple temperature values included in a temperature traversal range, and the temperature traversal range is the change range of the ambient temperature controlled for detection by the autofocus device.

[0030] Optionally, the autofocus device includes a coaxial autofocus device and an off-axis autofocus device. The coaxial autofocus device is an autofocus device through which the light beam generated by the light source illumination module passes through the objective lens, and the off-axis autofocus device is an autofocus device through which the light beam generated by the light source illumination module does not pass through the objective lens.

[0031] Optionally, the autofocus device includes a chuck for fixing a to-be-tested object. The calibration tool includes a standard wafer and a calibration module. The standard wafer is a wafer fixed by the chuck, and the distance between the calibration module and the chuck is less than a distance threshold.

[0032] Optionally, the difference between the central density and the edge density corresponding to the pattern is greater than a preset threshold.

[0033] In a second aspect, an embodiment of the present application provides a calibration device, and the device includes: an acquisition unit, an image unit, a determination unit, and a calibration unit;

[0034] The acquisition unit is configured to acquire multiple temperature values, a current temperature, and multiple focal plane compensation values. The current temperature is the temperature of the environment where the autofocus device is located, and the current temperature varies among the multiple temperature values;

[0035] The image unit is configured to, if the current temperature reaches a target temperature value among the multiple temperature values, acquire multiple detection images corresponding to a calibration tool according to the multiple focal plane compensation values. The calibration tool includes a pattern for image calibration;

[0036] The determining unit is configured to determine, according to the sharpness corresponding to each of the multiple detection images, the focal plane compensation value corresponding to the detection image with the highest sharpness as the target focal plane compensation value corresponding to the target temperature value;

[0037] The calibration unit is configured to use each of the temperature values as the target temperature value, determine the target focal plane compensation value corresponding to each of the temperature values, and obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value.

[0038] As a possible implementation, the apparatus further includes a detection unit, an application unit, and a compensation unit:

[0039] The detection unit is configured to obtain a detection temperature, where the detection temperature is the ambient temperature when the autofocus device is used to detect a to-be-detected object;

[0040] The application unit is configured to determine the target focal plane compensation value corresponding to the detection temperature according to the compensation change relationship;

[0041] The compensation unit is configured to obtain a detection image of the to-be-detected object after compensating the autofocus device according to the target focal plane compensation value corresponding to the detection temperature.

[0042] As a possible implementation, the determining unit includes a fraction determining unit and a first compensation value determining unit:

[0043] The fraction determining unit is configured to determine the sharpness scores corresponding to each of the multiple detection images according to a sharpness algorithm;

[0044] The first compensation value determining unit is configured to determine the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

[0045] As a possible implementation, the sharpness algorithm includes a first algorithm and a second algorithm, and the fraction determining unit is specifically configured to:

[0046] Determine the first sharpness scores corresponding to each of the multiple detection images according to the first algorithm;

[0047] Determine the second sharpness scores corresponding to each of the multiple detection images according to the second algorithm;

[0048] The first compensation value determining unit is specifically configured to:

[0049] Determine the sharpness scores corresponding to each of the multiple detection images according to the first sharpness scores and the second sharpness scores corresponding to each of the multiple detection images;

[0050] Determine the focal plane compensation value corresponding to the detection image with the highest clarity score as the target focal plane compensation value corresponding to the target temperature value.

[0051] As a possible implementation, the determining unit includes a difference determining unit and a second compensation value determining unit:

[0052] The difference determining unit is configured to determine the image differences between the multiple detection images and the target image respectively;

[0053] The second compensation value determining unit is configured to determine the focal plane compensation value corresponding to the detection image with the smallest image difference as the target focal plane compensation value corresponding to the target temperature value, where the target image is an image with a clarity greater than the clarity threshold.

[0054] As a possible implementation, the multiple focal plane compensation values are the multiple focal plane compensation values included in the compensation traversal range.

[0055] As a possible implementation, the multiple temperature values are the multiple temperature values included in the temperature traversal range, and the temperature traversal range is the change range of the ambient temperature controlled for detection by the autofocus device.

[0056] As a possible implementation, the autofocus device includes a coaxial autofocus device and an off-axis autofocus device. The coaxial autofocus device is an autofocus device through which the light beam generated by the light source illumination module passes through the objective lens, and the off-axis autofocus device is an autofocus device through which the light beam generated by the light source illumination module does not pass through the objective lens.

[0057] As a possible implementation, the autofocus device includes a chuck for fixing the object to be measured. The calibration tool includes a standard wafer and a calibration module. The standard wafer is a wafer fixed by the chuck, and the distance between the calibration module and the chuck is less than the distance threshold.

[0058] As a possible implementation, the difference between the central density and the edge density of the pattern is greater than a preset threshold.

[0059] In a third aspect, an embodiment of the present application provides a computer device, which includes a processor and a memory:

[0060] The memory is used to store a computer program and transmit the computer program to the processor;

[0061] The processor is configured to execute the method described in the first aspect above according to the computer program.

[0062] Fourthly, an embodiment of the present application provides a computer-readable storage medium for storing a computer program for executing the method described in the first aspect above.

[0063] Fifthly, an embodiment of the present application provides a computer program product including a computer program, which, when running on a computer device, causes the computer device to execute the method described in the first aspect above.

[0064] It can be seen from the above technical solutions that the present application has at least the following beneficial effects:

[0065] Obtain multiple temperature values, the current temperature, and multiple focal plane compensation values. The current temperature is the temperature of the environment where the autofocus device is located, and the current temperature varies among the multiple temperature values. If the current temperature reaches the target temperature value among the multiple temperature values, obtain multiple detection images corresponding to the calibration tool according to the multiple focal plane compensation values. The calibration tool includes a pattern for image calibration. Determine the focal plane compensation value corresponding to the detection image with the highest clarity as the target focal plane compensation value corresponding to the target temperature value based on the clarity corresponding to each of the multiple detection images. Take each temperature value as the target temperature value, determine the target focal plane compensation value corresponding to each temperature value, and obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value. Thus, through calibration, target focal plane compensation values with better compensation difference effects corresponding to each temperature value are obtained, so that the focal plane compensation value can be adjusted according to the compensation change relationship adapted to the environmental temperature change, improving the accuracy of the compensation difference, making the autofocus ability of the autofocus device stronger, and obtaining clearer detection images. Description of the Drawings

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0067] Figure 1 It is a schematic flowchart of a calibration method provided by an embodiment of the present application;

[0068] Figure 2 It is a schematic diagram of a coaxial autofocus device provided by an embodiment of the present application;

[0069] Figure 3 It is a schematic diagram of an off-axis autofocus device provided by an embodiment of the present application;

[0070] Figure 4A flowchart showing the process of an application calibration method scenario provided by an embodiment of the present application;

[0071] Figure 5 A schematic structural diagram of a calibration device provided by an embodiment of the present application;

[0072] Figure 6 A schematic structural diagram of a computer device provided by an embodiment of the present application. Detailed implementation manners

[0073] Embodiments of the present application will be described in more detail with reference to the accompanying drawings. Although some embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not used to limit the protection scope of the present application.

[0074] As mentioned in the background art, in the related art, a focal plane compensation value is used to compensate for the difference between the focal plane of an autofocus device and the imaging focal plane. Specifically: the focal plane of the autofocus device + the focal plane compensation value = the imaging focal plane, which is a compensation correspondence relationship under the ideal condition of a constant ambient temperature. However, even when temperature control is performed by control devices such as a temperature controller, it is difficult to maintain the temperature of the actual environment where the autofocus device is located at an absolutely constant temperature, and the autofocus device is highly sensitive to temperature. When the ambient temperature changes, the focal plane of the autofocus device will drift, and at the same time, the imaging focal plane will also drift. As a result, the difference between the two will change with temperature, and it is difficult to compensate for this temperature-varying difference with a fixed focal plane compensation value, resulting in inaccurate focus tracking and difficulty in obtaining a clear image of the object to be measured.

[0075] Based on this, embodiments of the present application provide a calibration method and related device. By obtaining a plurality of detection images of a calibration tool corresponding to different focal plane compensation values at multiple temperature values, the focal plane compensation value corresponding to the detection image with the highest clarity is determined as the target focal plane compensation value, so as to obtain a target focal plane compensation value with a better compensation difference effect corresponding to each temperature value, and obtain a compensation change relationship that can adapt to the change of the ambient temperature, adjust the focal plane compensation value, improve the accuracy of the compensation difference, make the focus tracking ability of the autofocus device stronger, and obtain a clearer detection image.

[0076] See Figure 1 , this figure is a flowchart showing the calibration method provided by an embodiment of the present application. For ease of description, the following embodiments will be described by taking the execution subject of this calibration method as an autofocus device as an example. As Figure 1 shown, this calibration method includes S101 - S104.

[0077] S101: Obtain multiple temperature values, the current temperature, and multiple focal plane compensation values.

[0078] The multiple temperature values can be multiple temperature values with continuous numerical values and uniform intervals. For example, 23.1°C (degrees Celsius), 23.2°C, 23.3°C, 23.4°C, and so on, in order to calibrate a more complete and continuous variation relationship of the focal plane compensation value with the temperature value. The current temperature is the temperature of the environment where the autofocus device is located, which varies among the multiple temperature values. The temperature of the environment where the autofocus device is located can reflect the operating temperature maintained when the autofocus device is not affected by internal factors such as the working duration. As can be seen from the foregoing, the autofocus device is highly sensitive to temperature, which is reflected in that when the temperature of its environment changes, the temperature changes during the calibration process corresponding to different temperature values can simulate the temperature changes in the actual detection process.

[0079] It should be noted that the embodiments of the present application do not limit how the current temperature changes among the multiple temperature values. The current temperature can change naturally according to natural objective factors such as the weather, or the current temperature can be controlled to change through temperature control means to enable the current temperature to traverse multiple temperature values. For example, the environmental temperature inside the cabin where the autofocus device is located is controlled by a temperature controller to change according to multiple temperature values. As a possible implementation, the current temperature can be obtained through a temperature sensor installed in the environment where the autofocus device is located.

[0080] The focal plane compensation value is used to compensate for the difference between the focal plane of the autofocus device and the imaging focal plane. This difference is caused by reasons such as chromatic aberration and alignment errors. For example, the heights of the focal plane of the autofocus device and the imaging focal plane are different, or there is a position misalignment. However, since the operating temperature of the autofocus device may be affected by the change in the ambient temperature, the focal plane and the imaging focal plane of the autofocus device will deviate, resulting in the non-constancy of this difference. Therefore, a preset focal plane compensation value cannot be used to compensate for the difference between the two.

[0081] For a clearer elaboration, the following takes the focal plane compensation value used to compensate for the height difference between the focal plane of the autofocus device and the imaging focal plane as an example for illustration.

[0082] S102: If the current temperature reaches the target temperature value among the multiple temperature values, obtain multiple detection images corresponding to the calibration tool according to the multiple focal plane compensation values.

[0083] The target temperature value is a temperature value to be calibrated among the multiple temperature values. The calibration tool is a test object used for image calibration, including a pattern for image calibration.

[0084] In a possible implementation, the multiple focal plane compensation values are the multiple focal plane compensation values included in the compensation traversal range, and the compensation traversal range is the preset traversal range of the focal plane compensation values. Those skilled in the art can set it according to the time-consuming for calibrating the compensation change relationship. For example, the compensation traversal range can be ±1 / 4 DOF (Depth of Field).

[0085] Therefore, by traversing the multiple focal plane compensation values included in the compensation traversal range (such as ±1 / 4 DOF), the number of traversals can be reduced, the calibration duration can be shortened, and the efficiency of calibrating the compensation change relationship can be improved.

[0086] In a possible implementation, the autofocus device includes a chuck, which is a device for fixing the object to be measured. The calibration tool includes a standard wafer and a calibration module. The standard wafer is a wafer fixed by the chuck and is usually a reference standard sample for calibration and detection. The distance between the calibration module and the chuck is less than the distance threshold. When image calibration is required, the pattern corresponding to the calibration module does not need to be replaced and can quickly appear in the field of view of the objective lens, which is more convenient and fast.

[0087] The pattern included in the calibration tool is used for clarity recognition, such as a wheel pattern, a grid pattern, etc. In a possible implementation, the difference between the central density and the edge density corresponding to the pattern is greater than a preset threshold. The density is used to reflect the density of the pattern elements. The more elements there are per unit area, the higher the density of that area. When the difference between the central density and the edge density corresponding to the pattern is greater than the preset threshold, it means that the density of the pattern elements is distributed differently at different positions and is rich in variation, which can enhance the clarity recognition ability of the autofocus device for the pattern, thereby improving the accuracy of the target focal plane compensation value obtained by calibration.

[0088] The detection image is an image obtained by the detection device corresponding to the autofocus device by photographing the object to be measured. The autofocus device is used to provide the autofocus function for the detection device. If the current temperature reaches the target temperature value, then at this target temperature value, the autofocus device is compensated by using multiple focal plane compensation values, and then multiple detection images corresponding to the calibration tool under the compensation of different focal plane compensation values are respectively obtained. That is, the compensation effects of different focal plane compensation values are different, and the focus tracking accuracy brought is also different. Different focal plane compensation values correspond to different detection images, and the clarity of different detection images is also different.

[0089] S103: According to the clarity corresponding to the multiple detection images respectively, determine the focal plane compensation value corresponding to the detection image with the highest clarity as the target focal plane compensation value corresponding to the target temperature value.

[0090] The target focal plane compensation value is the focal plane compensation value with higher compensation accuracy among multiple focal plane compensation values at the target temperature value. For multiple detected images corresponding to multiple focal plane compensation values, by determining the sharpness corresponding to each of the multiple detected images, such as the first sharpness corresponding to the first detected image, the second sharpness corresponding to the second detected image, etc., the focal plane compensation value corresponding to the detected image with the highest sharpness is determined as the target focal plane compensation value corresponding to the target temperature value, that is, the focal plane compensation value corresponding to the sharpest detected image is the focal plane compensation value with more accurate compensation among multiple focal plane compensation values, and the focal plane compensation value with more accurate compensation is determined as the target focal plane compensation value.

[0091] The present application does not limit how to determine the sharpness of the detected image. The following takes two determination methods as examples for illustration.

[0092] Determination method 1: Determine the sharpness scores corresponding to each of the multiple detected images according to the sharpness algorithm. The focal plane compensation value corresponding to the detected image with the highest sharpness score is determined as the target focal plane compensation value corresponding to the target temperature value.

[0093] The sharpness score is an index reflecting the sharpness of the detected image, and the sharpness algorithm is an algorithm for determining the sharpness score of the detected image. For example:

[0094] (1) Gradient Operator method: Common gradient operators include Sobel, Prewitt, and Roberts, etc. The difference between each pixel in the image and its neighboring pixels is calculated through the gradient operator to measure the edge strength of the image. The sharpness of the detected image is determined by comparing the difference in edge strength between the detected image and the target image, and the detected image with the smallest difference in edge strength is determined as the detected image with the highest sharpness.

[0095] (2) Laplacian Operator method: The Laplacian Operator is a second-order differential operator used to detect rapid brightness changes in the image. The Laplacian Operator highlights the edges and other high-frequency components in the image through convolution operations on the image. The clearer the image, the larger the result of its Laplace transform. The detected image with the largest result after Laplace transform is determined as the detected image with the highest sharpness.

[0096] The embodiment of the present application also provides a method for determining the target focal plane compensation value by cross-validation. The sharpness algorithm includes a first algorithm and a second algorithm. Determine the first sharpness scores corresponding to each of the multiple detected images according to the first algorithm. Determine the second sharpness scores corresponding to each of the multiple detected images according to the second algorithm.

[0097] Based on the first sharpness scores and the second sharpness scores respectively corresponding to multiple detection images, determine the sharpness scores respectively corresponding to the multiple detection images. For example, the average sharpness scores respectively corresponding to each focal plane compensation value can be obtained by performing an averaging operation on the first sharpness score and the second sharpness score, and the focal plane compensation value with the highest average sharpness score is determined as the focal plane compensation value with the highest sharpness score by comparison. Finally, the focal plane compensation value with the highest sharpness score is determined as the target focal plane compensation value.

[0098] Different sharpness algorithms focus on different aspects when calculating the image difference. For example, the gradient operator method focuses on the edge intensity, and the Laplace operator focuses on the brightness change. By using multiple sharpness algorithms to determine the sharpness of the detection image, the comprehensiveness and accuracy of sharpness recognition can be improved, so that the sharpness score of the detection image can be calculated more accurately, and a more accurate target focal plane compensation value can be obtained.

[0099] Determination method two: Determine the image differences between multiple detection images and the target image respectively. The focal plane compensation value corresponding to the detection image with the smallest image difference is determined as the target focal plane compensation value corresponding to the target temperature value, and the target image is an image with sharpness greater than the sharpness threshold.

[0100] The target image is an image corresponding to the calibration tool with sharpness greater than the sharpness threshold. The image difference between the detection image and the target image can reflect the sharpness of the detection image. The greater the difference between the detection image and the target image, the lower the sharpness.

[0101] For multiple detection images corresponding to multiple focal plane compensation values, by determining the image differences between multiple detection images and the target image respectively, such as the first image difference corresponding to the first detection image, the second image difference corresponding to the second detection image, etc., the focal plane compensation value corresponding to the detection image with the smallest image difference can be determined as the target focal plane compensation value corresponding to the target temperature value, that is, the focal plane compensation value corresponding to the clearest detection image is the more accurate compensation value among multiple focal plane compensation values, and the more accurate compensation value is determined as the target focal plane compensation value.

[0102] S104: Respectively use each temperature value as the target temperature value, determine the target focal plane compensation value respectively corresponding to each temperature value, and obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value.

[0103] Taking each temperature value as the target temperature value respectively and executing S102 - S103, the target focal plane compensation value corresponding to each temperature value can be obtained. There is a one - to - one mapping relationship between the temperature value and the focal plane compensation value. This set of mapping relationships can reflect how the target focal plane compensation value that accurately reflects the compensation effect changes with the change of the temperature value, and thus the compensation change relationship of the target focal plane compensation value with the temperature value is obtained. As an implementation method, the compensation change relationship is a curve of the target focal plane compensation value changing with the temperature value.

[0104] Through the compensation change relationship, the target focal plane compensation value with more accurate compensation corresponding to different temperature values can be directly determined. When using the target focal plane compensation value to compensate for the height difference between the focal plane of the autofocus device and the imaging focal plane, the object plane can be maintained at the position of the focal plane of the autofocus device + the target focal plane compensation value, thereby reducing the height difference between the object plane and the imaging focal plane caused by focal plane drift, making the autofocus of the autofocus device more accurate and the obtained detection image clearer.

[0105] For example, the detection temperature can be obtained. The detection temperature is the ambient temperature when the autofocus device is used to detect the object to be measured. Determine the target focal plane compensation value corresponding to the detection temperature according to the compensation change relationship. According to the target focal plane compensation value corresponding to the detection temperature, compensate the focal plane of the autofocus device through the target focal plane compensation value to obtain the target compensated focal plane, so that the object plane corresponding to the object to be measured is at the position where the target compensated focal plane is located, and then obtain the detection image of the object to be measured.

[0106] By obtaining the detection temperature in real - time and dynamically adjusting the focal plane compensation value according to the compensation change relationship, the autofocus device can make the object to be measured in a relatively accurate position under various ambient temperature conditions, improve the autofocus ability of the autofocus device, and thus obtain a clearer detection image.

[0107] As can be seen from the above technical solution, multiple temperature values, the current temperature, and multiple focal plane compensation values are obtained. The current temperature is the temperature of the environment where the autofocus device is located, and the current temperature varies between multiple temperature values. If the current temperature reaches the target temperature value among the multiple temperature values, according to the multiple focal plane compensation values, multiple detection images corresponding to the calibration tool are obtained. The calibration tool includes a pattern for image calibration. According to the sharpness corresponding to each of the multiple detection images, the focal plane compensation value corresponding to the detection image with the highest sharpness is determined as the target focal plane compensation value corresponding to the target temperature value. Each temperature value is used as the target temperature value respectively, and the target focal plane compensation value corresponding to each temperature value is determined, so as to obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value. Thus, through calibration, the target focal plane compensation values with better compensation difference effects corresponding to each temperature value are obtained, so that the focal plane compensation value can be adjusted according to the compensation change relationship adapted to the environmental temperature change, the accuracy of the compensation difference is improved, the focusing ability of the autofocus device is stronger, and the obtained detection images are clearer.

[0108] In a possible implementation manner, when the autofocus device performs detection, temperature control means are adopted for the environment where the autofocus device is located, so that the environmental temperature is maintained within the temperature traversal range, that is, the temperature traversal range is the change range of the environmental temperature control when the autofocus device is used for detection. Based on this, in the calibration process, the multiple temperature values obtained can be multiple temperature values within the temperature traversal range. For example, the temperature traversal range is 23°C - 24°C, and the multiple temperature values are multiple temperature values at intervals of 0.1°C between 23°C and 24°C, such as 23.1°C, 23.2°C, 23.3°C, and so on.

[0109] Thus, the working conditions covered in the calibration process are more matched with the working conditions during the actual detection of the automatic detection device, so that the obtained compensation change relationship is more targeted. At the same time, the temperature traversal range is reduced, the calibration duration is shortened, and the calibration efficiency is improved.

[0110] The embodiments of the present application do not limit the type of the autofocus device, that is, the above calibration process can cover various types of autofocus devices. For example, the autofocus device may include a coaxial autofocus device and an off-axis autofocus device. Refer to Figure 2 , Figure 2 which is a schematic diagram of a coaxial autofocus device provided by an embodiment of the present application. The coaxial autofocus device is coupled with the objective lens, and the beam generated by its light source illumination module passes through the objective lens. Refer to Figure 3 , Figure 3 which is a schematic diagram of an off-axis autofocus device provided by an embodiment of the present application. The off-axis autofocus device is not coupled with the objective lens, and the beam generated by its light source illumination module does not pass through the objective lens.

[0111] Refer to Figure 4 ,Figure 4 A flowchart showing a scenario of an application calibration method provided by an embodiment of the present application.

[0112] In this application scenario, it is divided into a calibration process and a detection process. In the calibration process, first, move the calibration tool under the objective lens, set the focal plane compensation value to zero to traverse the focal plane compensation value. The focal plane compensation value is used to correct the deviation between the focal plane of the autofocus device and the imaging focal plane, playing a role similar to moving the focal plane. Determine the possible change range of the ambient temperature, and this change range is used to indicate the range of temperature value traversal during the calibration process. According to the possible change range of the ambient temperature, obtain X ambient temperatures through the temperature sensor, and control the ambient temperature to change between X temperature values within the change range, that is, traverse X ambient temperatures within the change range. For example, if the change range is 23°C - 24°C, control the ambient temperature to change in steps of 0.1°C. For the target temperature value, traverse different focal plane compensation values, take detection images corresponding to different focal plane compensation values in the case of following focus, and determine the focal plane compensation value corresponding to the detection image with the highest clarity by comparison. Determine the focal plane compensation value corresponding to the detection image with the highest clarity as the target focal plane compensation value corresponding to the target temperature value, and the calibration process of the target temperature value is completed. Then, by taking each ambient temperature as the target temperature value respectively and executing the above calibration process, the entire calibration process is ended.

[0113] In the detection process, during the operation of the system, the ambient temperature is detected in real time through the temperature sensor, and according to the ambient temperature, the calibrated target focal plane compensation value is sent down, so as to compensate the focal plane of the autofocus device through the target focal plane compensation value to make the imaging clearer.

[0114] See Figure 5 , Figure 5 A calibration device provided by an embodiment of the present application. The device 500 includes an acquisition unit 501, an image unit 502, a determination unit 503, and a calibration unit 504;

[0115] The acquisition unit 501 is configured to acquire a plurality of temperature values, the current temperature, and a plurality of focal plane compensation values, where the current temperature is the temperature of the environment where the autofocus device is located, and the current temperature changes among the plurality of temperature values;

[0116] The image unit 502 is configured to, if the current temperature reaches the target temperature value among the plurality of temperature values, acquire a plurality of detection images corresponding to the calibration tool according to the plurality of focal plane compensation values, where the calibration tool includes a pattern for image calibration;

[0117] The determination unit 503 is configured to determine the focal plane compensation value corresponding to the detection image with the highest clarity as the target focal plane compensation value corresponding to the target temperature value according to the clarity corresponding to the plurality of detection images;

[0118] The calibration unit 504 is configured to use each of the temperature values as the target temperature value, determine the target focal plane compensation value corresponding to each of the temperature values, and obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value.

[0119] As can be seen from the above technical solutions, the calibration device provided in the embodiments of the present application includes an acquisition unit, an image unit, a determination unit, and a calibration unit. According to the acquisition unit that acquires a plurality of temperature values, the current temperature, and a plurality of focal plane compensation values, the current temperature is the temperature of the environment where the autofocus device is located, and the current temperature varies among the plurality of temperature values. If the current temperature reaches the target temperature value among the plurality of temperature values, according to the plurality of focal plane compensation values, the image unit acquires a plurality of detection images corresponding to the calibration tool. The calibration tool includes a pattern for image calibration. According to the determination unit, based on the sharpness corresponding to each of the plurality of detection images, the focal plane compensation value corresponding to the detection image with the highest sharpness is determined as the target focal plane compensation value corresponding to the target temperature value. According to the calibration unit, each of the temperature values is used as the target temperature value, the target focal plane compensation value corresponding to each of the temperature values is determined, and the compensation change relationship of the target focal plane compensation value with respect to the temperature value is obtained. Thus, through calibration, the target focal plane compensation values with better compensation difference effects corresponding to each temperature value are obtained, so that the focal plane compensation value can be adjusted according to the compensation change relationship adapted to the environmental temperature change, the accuracy of the compensation difference is improved, the focusing ability of the autofocus device is stronger, and the acquired detection images are clearer.

[0120] As a possible implementation, the device further includes a detection unit, an application unit, and a compensation unit:

[0121] The detection unit is configured to acquire a detection temperature, where the detection temperature is the temperature of the environment when the autofocus device is used to detect a to-be-detected object;

[0122] The application unit is configured to determine the target focal plane compensation value corresponding to the detection temperature according to the compensation change relationship;

[0123] The compensation unit is configured to acquire a detection image of the to-be-detected object after compensating the autofocus device according to the target focal plane compensation value corresponding to the detection temperature.

[0124] As a possible implementation, the determination unit includes a score determination unit and a first compensation value determination unit:

[0125] The score determination unit is configured to determine the sharpness scores corresponding to each of the plurality of detection images according to a sharpness algorithm;

[0126] The first compensation value determining unit is configured to determine the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

[0127] As a possible implementation, the sharpness algorithm includes a first algorithm and a second algorithm, and the score determining unit is specifically configured to:

[0128] Determine the first sharpness scores respectively corresponding to the multiple detection images according to the first algorithm;

[0129] Determine the second sharpness scores respectively corresponding to the multiple detection images according to the second algorithm;

[0130] The first compensation value determining unit is specifically configured to:

[0131] Determine the sharpness scores respectively corresponding to the multiple detection images according to the first sharpness scores and the second sharpness scores respectively corresponding to the multiple detection images;

[0132] Determine the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

[0133] As a possible implementation, the determining unit includes a difference determining unit and a second compensation value determining unit:

[0134] The difference determining unit is configured to determine the image differences between the multiple detection images and a target image respectively;

[0135] The second compensation value determining unit is configured to determine the focal plane compensation value corresponding to the detection image with the smallest image difference as the target focal plane compensation value corresponding to the target temperature value, and the target image is an image with a sharpness greater than a sharpness threshold.

[0136] As a possible implementation, the multiple focal plane compensation values are the multiple focal plane compensation values included in the compensation traversal range.

[0137] As a possible implementation, the multiple temperature values are the multiple temperature values included in the temperature traversal range, and the temperature traversal range is the change range of the ambient temperature controlled for detection by the autofocus device.

[0138] As a possible implementation, the autofocus device includes a coaxial autofocus device and an off-axis autofocus device. The coaxial autofocus device is an autofocus device through which the light beam generated by the light source illumination module passes through the objective lens, and the off-axis autofocus device is an autofocus device through which the light beam generated by the light source illumination module does not pass through the objective lens.

[0139] As a possible implementation manner, the autofocus device includes a chuck for fixing the object to be measured. The calibration tool includes a standard wafer and a calibration module. The standard wafer is a wafer fixed by the chuck, and the distance between the calibration module and the chuck is less than a distance threshold.

[0140] As a possible implementation manner, the difference between the central density and the edge density of the pattern is greater than a preset threshold.

[0141] See Figure 6 , an embodiment of the present application further provides a computer device, which includes a memory 601 and a processor 602:

[0142] The memory is used to store a computer program and transmit the computer program to the processor;

[0143] The processor is used to execute the method in the above method embodiment according to the computer program.

[0144] An embodiment of the present application further provides a computer-readable storage medium, which is characterized in that the computer-readable storage medium is used to store a computer program, and the computer program is used to execute the method in the above method embodiment.

[0145] An embodiment of the present application further provides a computer program product including a computer program. When it runs on a computer device, it causes the computer device to execute the method in the above method embodiment.

[0146] It should be noted that the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the system or device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0147] The term "including" and its variants used herein are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0148] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or its similar expressions refer to any combination of these items, including any combination of single items (one) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0149] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0150] The steps of the methods or algorithms described in connection with the embodiments disclosed herein can be implemented directly in hardware, software modules executed by a processor, or a combination of both. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0151] The above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A calibration method, characterized in that, Applied to an autofocus device, the method includes: Acquire multiple temperature values, a current temperature, and multiple focal plane compensation values, wherein the current temperature is the temperature of an environment where the autofocus device is located, and the current temperature varies between the multiple temperature values; If the current temperature reaches a target temperature value among the multiple temperature values, acquiring multiple detection images corresponding to a calibration tool according to the multiple focal plane compensation values, the calibration tool including a pattern for image calibration; According to the sharpnesses respectively corresponding to the plurality of detection images, the focus plane compensation value corresponding to the detection image with the highest sharpness is determined as the target focus plane compensation value corresponding to the target temperature value; Each of the temperature values is used as the target temperature value, and the target focal plane compensation value corresponding to each of the temperature values is determined to obtain a compensation variation relationship between the target focal plane compensation value and the temperature value.

2. The method according to claim 1, wherein The method further comprises: Acquiring a detection temperature, where the detection temperature is the ambient temperature of the environment when the autofocus device is used to detect the object to be detected; determining a target focal plane compensation value corresponding to the detected temperature according to the compensation change relationship; After compensating the automatic focusing device according to the target focal plane compensation value corresponding to the detected temperature, a detection image of the object to be detected is acquired.

3. The method according to claim 1, characterized in that, The step of determining, based on the sharpnesses respectively corresponding to the plurality of detection images, the focus plane compensation value corresponding to the detection image with the highest sharpness as the target focus plane compensation value corresponding to the target temperature value comprises: Determine the clarity scores corresponding to the plurality of detection images respectively according to a clarity algorithm; The focus plane compensation value corresponding to the detection image with the highest clarity score is determined as the target focus plane compensation value corresponding to the target temperature value.

4. The method according to claim 3, wherein The clarity algorithm includes a first algorithm and a second algorithm, and determining the clarity scores corresponding to the plurality of detection images respectively according to the clarity algorithm includes: Determine, according to the first algorithm, first clarity scores corresponding to each of the plurality of detection images; Determine, according to the second algorithm, second clarity scores corresponding to each of the plurality of detection images; The step of determining the focus plane compensation value corresponding to the detection image with the highest clarity score as the target focus plane compensation value corresponding to the target temperature value includes: Determining the clarity scores corresponding to the plurality of detection images respectively according to the first clarity scores and the second clarity scores corresponding to the plurality of detection images respectively; The focus plane compensation value corresponding to the detection image with the highest clarity score is determined as the target focus plane compensation value corresponding to the target temperature value.

5. The method according to claim 1, wherein The step of determining, based on the sharpnesses respectively corresponding to the plurality of detection images, the focus plane compensation value corresponding to the detection image with the highest sharpness as the target focus plane compensation value corresponding to the target temperature value comprises: Determining image differences between each of the plurality of detection images and the target image; The focus plane compensation value corresponding to the detection image with the smallest image difference is determined as the target focus plane compensation value corresponding to the target temperature value, and the target image is an image with a clarity greater than a clarity threshold.

6. The method according to claim 1, characterized in that The multiple focal plane compensation values are multiple focal plane compensation values included in the compensation traversal range.

7. The method according to claim 1, wherein The multiple temperature values are the multiple temperature values included in the temperature traversal range, and the temperature traversal range is the change range of the ambient temperature control for the autofocus device during detection.

8. The method according to claim 1, characterized in that, The autofocus device includes a coaxial autofocus device and an off-axis autofocus device. The coaxial autofocus device is an autofocus device through which the light beam generated by the light source illumination module passes through the objective lens, and the off-axis autofocus device is an autofocus device through which the light beam generated by the light source illumination module does not pass through the objective lens.

9. The method according to claim 1, wherein The autofocus device includes a chuck for fixing the object to be measured. The calibration tool includes a standard wafer and a calibration module. The standard wafer is a wafer fixed by the chuck, and the distance between the calibration module and the chuck is less than a distance threshold.

10. The method according to claim 1, characterized in that The difference between the central density and the edge density corresponding to the pattern is greater than a preset threshold.

11. A calibration device, characterized in that, Applied to an autofocus device, the device includes: an acquisition unit, an image unit, a determination unit, and a calibration unit; The acquisition unit is configured to acquire multiple temperature values, a current temperature, and multiple focal plane compensation values. The current temperature is the temperature of the environment where the autofocus device is located, and the current temperature varies among the multiple temperature values. The image unit is configured to, if the current temperature reaches a target temperature value among the multiple temperature values, acquire multiple detection images corresponding to the calibration tool according to the multiple focal plane compensation values. The calibration tool includes a pattern for image calibration. The determination unit is configured to determine, according to the sharpness corresponding to the multiple detection images respectively, the focal plane compensation value corresponding to the detection image with the highest sharpness as the target focal plane compensation value corresponding to the target temperature value. The calibration unit is configured to use each of the temperature values as the target temperature value, determine the target focal plane compensation value corresponding to each of the temperature values respectively, and obtain the compensation change relationship of the target focal plane compensation value with respect to the temperature value.

12. The device according to claim 11, characterized in that, The device further includes a detection unit, an application unit, and a compensation unit: The detection unit is configured to acquire a detection temperature, which is the ambient temperature when the autofocus device is used to detect the object to be measured. The application unit is configured to determine the target focal plane compensation value corresponding to the detection temperature according to the compensation change relationship. The compensation unit is configured to acquire a detection image of the object to be measured after compensating the autofocus device according to the target focal plane compensation value corresponding to the detection temperature.

13. The device according to claim 11, characterized in that, The determination unit includes a score determination unit and a first compensation value determination unit: The score determination unit is configured to determine the sharpness scores corresponding to the multiple detection images respectively according to a sharpness algorithm. The first compensation value determination unit is configured to determine the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

14. The device according to claim 13, characterized in that, The sharpness algorithm includes a first algorithm and a second algorithm. Specifically, the score determination unit is configured to: Determine the first sharpness scores corresponding to the multiple detection images respectively according to the first algorithm; Determine the second sharpness scores corresponding to the multiple detection images respectively according to the second algorithm; Specifically, the first compensation value determination unit is configured to: Determine the sharpness scores corresponding to the multiple detection images respectively according to the first sharpness scores and the second sharpness scores corresponding to the multiple detection images respectively; Determine the focal plane compensation value corresponding to the detection image with the highest sharpness score as the target focal plane compensation value corresponding to the target temperature value.

15. The device according to claim 11, wherein The determination unit includes a difference determination unit and a second compensation value determination unit: The difference determination unit is configured to determine the image differences between the multiple detection images and a target image respectively; The second compensation value determination unit is configured to determine the focal plane compensation value corresponding to the detection image with the smallest image difference as the target focal plane compensation value corresponding to the target temperature value, where the target image is an image with a sharpness greater than a sharpness threshold.

Images