A method and system for locating the center of a light spot

Abstract

The application provides a light spot center positioning method and a positioning system. The method is applied to a controller in a light spot center positioning system, and the positioning system further comprises a first optical energy sensor, a second optical energy sensor, a workbench and a light source. The method comprises the following steps: controlling the workbench to move in a spiral manner; determining whether the first optical energy sensor has entered a target range of a light spot according to a light intensity ratio of a corresponding position of each step; if yes, recording a first position where the first optical energy sensor is located and controlling the workbench to stop moving; taking the first position as a starting point, controlling the workbench to perform line scanning along a coordinate axis direction of a plane where the workbench is located, and determining an edge position of the light spot according to a light intensity ratio in the line scanning process; and positioning the center of the light spot according to the edge position of the light spot. In this way, the light spot center can be quickly and accurately positioned automatically under the starting working condition of any direction and position.

Description

Technical Field

[0001] This application relates to the field of integrated circuit equipment technology, and in particular to a method and system for locating the center of a light spot. Background Technology

[0002] In the manufacturing and processing of integrated circuit equipment, the positioning of the spot center is of great significance and directly affects the processing quality. Current technologies often employ a combination of unidirectional linear scanning and threshold judgment to locate the spot center generated by the objective lens's optical axis.

[0003] However, when the initial position of the light spot deviates significantly, the sensor may fail to detect a valid signal for an extended period, leading to search failure. Furthermore, if the search path is poorly designed and the search direction is singular, it can easily get stuck in local blind spots, making a fully automatic, full-coverage positioning process impossible. Especially in actual production environments, due to factors such as mechanical installation errors and thermal drift, the position of the light spot is uncertain, making it difficult for traditional algorithms to reliably and quickly achieve positioning. In such cases, fully automatic spot positioning is impossible, requiring manual intervention, thus affecting the success rate and efficiency of spot center positioning. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method and system for locating the center of a light spot, which can quickly and accurately locate the center of the light spot automatically.

[0005] This application provides a method for locating the center of a light spot, applied to a controller in a light spot center positioning system. The positioning system further includes a first optical energy sensor, a second optical energy sensor, a worktable, and a light source. The light source projects a light spot onto the worktable. The first optical energy sensor is mounted on the worktable and is used to detect the light intensity on the surface of the worktable. The second optical energy sensor is used to detect the light intensity of the light source. The positioning method includes: The worktable is controlled to move in a spiral manner; wherein, each time the worktable moves one step, the light intensity ratio between the first light intensity detected at the location of the first optical energy sensor and the second light intensity detected by the second optical energy sensor is determined. Based on the light intensity ratio at each corresponding position, determine whether the first optical energy sensor has entered the target range of the light spot; If the first position of the first optical energy sensor has been entered, the first position of the first optical energy sensor is recorded and the worktable is controlled to stop moving. Starting from the first position, the worktable is controlled to perform line scanning along the coordinate axis direction of the plane, and the edge position of the light spot is determined according to the light intensity ratio during the line scanning process. The center of the light spot is located based on the edge position of the light spot.

[0006] Furthermore, the positioning method also includes: The worktable is controlled to perform a line scan again along the coordinate axis of the plane to determine the second position of the first optical energy sensor when the light intensity ratio is a second preset ratio. The worktable is controlled to perform step scanning along the Z-axis direction; wherein the Z-axis is perpendicular to the plane where the worktable is located; each time the worktable moves one step, the light intensity ratio between the first light intensity detected by the first optical energy sensor at the second position and the second light intensity detected by the second optical energy sensor is determined; The focal plane of the positioning system is determined based on the Z-axis positions to which the worktable moves and the corresponding light intensity ratios. Move the worktable to the focal plane and reposition the center of the light spot.

[0007] Furthermore, determining whether the first optical energy sensor has entered the target range of the light spot based on the light intensity ratio at each corresponding position includes: When the light intensity ratio at any step is greater than the first preset threshold, the worktable is controlled to move another step in the direction of that step, and it is determined whether the light intensity ratio is still greater than or equal to the first preset threshold. If it is still greater than or equal to the first preset threshold, then control the worktable to move one step again in the direction perpendicular to the movement direction of this step, and determine whether the light intensity ratio is still greater than the first preset threshold. If it is still greater than or equal to the first preset threshold, then it is determined that the first optical energy sensor has entered the target range of the light spot; If the value is less than the first preset threshold, the worktable is controlled to move two steps again in the opposite vertical direction to the movement direction of that step, and it is determined that the first optical energy sensor has entered the target range of the light spot.

[0008] Furthermore, after controlling the worktable to move two more steps in the opposite perpendicular direction to the movement direction of the previous step, the step of determining whether the first optical energy sensor has entered the target range of the light spot based on the light intensity ratio at the corresponding position of each step further includes: Determine whether the light intensity ratio is still greater than the first preset threshold; If it is still greater than or equal to the first preset threshold, then it is determined that the first optical energy sensor has entered the target range of the light spot; If the light intensity is less than the first preset threshold, the worktable is controlled to move again in a spiral manner from its current position, and the first optical energy sensor is re-determined whether it has entered the target range of the light spot based on the light intensity ratio at each corresponding position.

[0009] Furthermore, starting from the first position, the worktable is controlled to perform a line scan along the coordinate axis direction of the plane, and the edge position of the light spot is determined according to the light intensity ratio during the line scan process, including: For any direction of any coordinate axis, starting from the first position, the worktable is controlled to perform a line scan along that direction to determine the light intensity ratio corresponding to a position point at a predetermined distance from the starting point; wherein, the predetermined length is greater than the length of the light spot in that direction; The position point is iteratively selected between the position point and the starting point according to the binary search strategy until the edge position of the light spot in this direction is determined according to the light intensity ratio corresponding to the selected position point.

[0010] Furthermore, a binary search strategy is used to iteratively select a location point between the selected location point and the starting point until the edge position of the light spot in that direction is determined based on the light intensity ratio corresponding to the selected location point, including: For any selected location point, determine whether the light intensity ratio corresponding to that location point is equal to the first preset ratio; If equal, then that location is determined as the edge position of the light spot in that direction; If not equal, then determine whether the distance between the location point and the interval endpoint corresponding to the binary search strategy is less than or equal to the preset location precision; If the position is less than or equal to the preset position accuracy, the edge position of the light spot in that direction is determined based on the position point and the corresponding interval endpoint. If the accuracy is greater than the preset position precision, then the next position point is selected iteratively between the current position point and the corresponding interval endpoint according to the binary search strategy.

[0011] Furthermore, controlling the worktable to perform step scanning along the Z-axis includes: The worktable is controlled to perform the first step scan along the Z-axis with a first step length; The first Z-axis position is determined based on the light intensity ratio of each Z-axis position scanned during the first step of the scanning process; A second step scan is performed within a predetermined range around the first Z-axis position with a second step size; the second step size is smaller than the first step size.

[0012] Furthermore, based on the Z-axis positions moved by the worktable and the corresponding light intensity ratios, the focal plane of the positioning system is determined, including: Based on the Z-axis positions and corresponding light intensity ratios scanned during the second step scan, a second function relating the Z-axis positions and light intensity ratios is fitted; wherein, the second function is in the form of a parabola. The Z-axis position corresponding to the minimum value of the second function is determined as the location of the focal plane of the positioning system.

[0013] Furthermore, the first Z-axis position is determined based on the light intensity ratio corresponding to each Z-axis position scanned during the first step of the scanning process, including: When the light intensity ratio corresponding to any Z-axis position is less than the second preset threshold, the Z-axis position is determined as the first Z-axis position. When the light intensity ratio corresponding to each Z-axis position is greater than or equal to the second preset threshold, a first function between the Z-axis position and the light intensity ratio is fitted based on each Z-axis position and the corresponding light intensity ratio; wherein, the first function is in the form of a parabola; The Z-axis position corresponding to the minimum value of the first function is determined as the first Z-axis position.

[0014] This application embodiment also provides a positioning system for the center of a light spot, the positioning system including: a controller, a first optical energy sensor, a second optical energy sensor, a worktable, and a light source; The light source projects a light spot onto the worktable; the first optical energy sensor is mounted on the worktable to detect the light intensity on the worktable surface; the second optical energy sensor is used to detect the light intensity of the light source; and the controller is used to execute the steps of the light spot center positioning method described above.

[0015] This application provides a method and system for locating the center of a light spot. First, through a comprehensive spiral search, a position within the projected light spot on the workpiece table can be quickly located. Then, starting from this position, the edge position of the light spot is located by line scanning along the coordinate axis, thereby determining the center of the light spot. In this way, the center of the light spot can be automatically located quickly and accurately under any starting condition in any direction and position.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart of a method for locating the center of a light spot provided in an embodiment of this application is shown; Figure 2 This paper shows a schematic diagram of the structure of a spot center positioning system provided in an embodiment of this application; Figures 3(a) and (b) show schematic diagrams of a spiral search process provided in an embodiment of this application; Figure 4 A schematic diagram of a binary search process provided in an embodiment of this application is shown; Figure 5 A schematic diagram of a light spot center positioning method provided in an embodiment of this application is shown; Figure 6 A schematic diagram illustrating the positional relationship between energy and the focal plane provided in an embodiment of this application is shown; Figures 7(a) to (c) show experimental results of spot center positioning provided by an embodiment of this application; Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0020] Research has shown that locating the center of the optical spot is crucial in the manufacturing of integrated circuit equipment, directly impacting the processing quality. Current technologies often employ a combination of unidirectional linear scanning and threshold judgment to locate the center of the optical spot generated by the objective lens.

[0021] However, when the initial position of the light spot deviates significantly, the sensor may fail to detect a valid signal for an extended period, leading to search failure. Furthermore, if the search path is poorly designed and the search direction is singular, it can easily get stuck in local blind spots, making a fully automatic, full-coverage positioning process impossible. Especially in actual production environments, due to factors such as mechanical installation errors and thermal drift, the position of the light spot is uncertain, making it difficult for traditional algorithms to reliably and quickly achieve positioning. In such cases, fully automatic spot positioning is impossible, requiring manual intervention, thus affecting the success rate and efficiency of spot center positioning.

[0022] Based on this, embodiments of this application provide a method for locating the center of a light spot, so as to achieve rapid and accurate automatic positioning of the center of the light spot under any initial working condition in any direction and position.

[0023] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for locating the center of a light spot according to an embodiment of this application. The method is applied to a controller in a light spot center positioning system; the positioning system also includes a first optical energy sensor, a second optical energy sensor, a worktable, and a light source.

[0024] The system includes a light source projecting a light spot onto a worktable; a first optical energy sensor mounted on the worktable detects the light intensity (illuminance) on its surface; and a second optical energy sensor detects the light intensity of the light source. A controller can drive the worktable to move via a motor, causing the first optical energy sensor to move as well. Furthermore, the positioning system may include optical components for transmitting the light beam.

[0025] In one example, see Figure 2 , Figure 2 This is a schematic diagram of a spot center positioning system provided in an embodiment of this application. Figure 2 As shown, the positioning system includes a first optical energy sensor (SS sensor), a second optical energy sensor (ES sensor), a stage, a laser as a light source, a beam transmission mirror group, a homogenizing unit, a photomask, and an objective lens group. The positioning system also includes a controller and a drive motor. Figure 2 (Not shown in the image).

[0026] In practice, the light-transmitting hole on the photomask is moved to align with the nominal optical axis of the projection lens. Above the worktable, the laser source projects a uniform beam of light obtained through the homogenizing unit onto the workpiece stage through the light-transmitting hole on a dedicated photomask, forming a light spot. For ease of positioning, the light-transmitting hole is square. For example, 1.6 A 1.6mm square hole with an objective lens magnification of 0.25 theoretically creates a 0.4mm diameter on the wafer surface during processing. A 0.4mm square light spot. Other light source types can also be used, and this application does not impose any restrictions on them.

[0027] like Figure 1 As shown in the embodiments of this application, the positioning method includes: S101. Control the worktable to move in a spiral manner; wherein, each time the worktable moves one step, determine the light intensity ratio between the first light intensity detected at the location of the first optical energy sensor and the second light intensity detected by the second optical energy sensor.

[0028] In this step, the worktable moving in a spiral manner means that the worktable moves along a spiral trajectory; the position of the first optical energy sensor also changes under the influence of the worktable, so the position of the first optical energy sensor also forms a spiral trajectory.

[0029] Furthermore, the worktable moves in steps, and the step size can be determined based on the spot size, for example, 1 / N of the theoretical spot size, where N is a positive integer greater than 2. Taking a square spot as an example, the step size can be 1 / 4 of the side length. Each time the worktable moves one step, the first optical energy sensor detects the first light intensity at the position it reaches in that step, and simultaneously determines the intensity ratio between the first light intensity and the second light intensity detected by the second optical energy sensor. To improve positioning accuracy, the light intensity detected by the optical energy sensor can also be sampled and filtered.

[0030] S102. Determine whether the first optical energy sensor has entered the target range of the light spot based on the light intensity ratio at the corresponding position of each step.

[0031] In this embodiment, the purpose of the worktable moving in a spiral manner is to find a position within the projected light spot on the workpiece table surface through a spiral search. Therefore, in one possible implementation, when the light intensity ratio is greater than a first preset threshold, it is determined that the first optical energy sensor has entered the target range of the light spot, and the position of the first optical energy sensor is a position within the light spot. The first preset threshold can be determined through a pre-executed reference search process, in which the light intensity ratio when the first optical energy sensor is within the light spot is determined. For example, the first preset threshold is 80%.

[0032] In another possible implementation, to avoid misjudgments caused by single-point threshold comparison; and considering that the plane where the worktable is located may not be the optimal focal plane at the start of the search, the spot range on the worktable surface will be slightly larger than the spot range on the optimal focal plane due to defocusing. Therefore, the searched position should be kept close to the center of the spot to avoid exceeding the spot range on the optimal focal plane. Step S102 may include: S1021. When the light intensity ratio at any step position is greater than the first preset threshold, control the worktable to move another step in the direction of movement of that step, and determine whether the light intensity ratio is still greater than or equal to the first preset threshold.

[0033] Here, each step corresponds to a position where the first optical energy sensor reaches the location corresponding to that step of the worktable's movement. For example, when the worktable moves for the i-th step, the first optical energy sensor moves from position i-1 to position i. Assuming the light intensity ratio at step i is greater than a first preset threshold, the worktable is controlled to move another step (step i+1) in the same direction as step i. At this point, the first optical energy sensor moves from position i to position i+1 and determines whether the light intensity ratio at position i+1 is still greater than or equal to the first preset threshold.

[0034] S1022. If it is still greater than or equal to the first preset threshold, control the worktable to move one step again in the direction perpendicular to the moving direction of this step, and determine whether the light intensity ratio is still greater than the first preset threshold.

[0035] S1023. If it is still greater than or equal to the first preset threshold, then it is determined that the first optical energy sensor has entered the target range of the light spot.

[0036] S1024. If the value is less than the first preset threshold, control the worktable to move two more steps in the opposite vertical direction to the movement direction of this step, and determine that the first optical energy sensor has entered the target range of the light spot.

[0037] Regarding steps S1022 to S1024, it can be understood that the vertical direction of the movement in this step includes two possibilities: a 90-degree clockwise rotation and a 90-degree counter-clockwise rotation. If another step is taken in either vertical direction, because the position of the light spot is unknown, the new position may be closer to or further away from the center of the light spot. Therefore, after this second step, it is necessary to re-determine whether the light intensity ratio at the new position is still greater than the first preset threshold.

[0038] If the position is still greater than or equal to the first preset threshold, it indicates that the position is closer to the center of the light spot, confirming that the first optical energy sensor has entered the target range of the light spot. If the position is less than the first preset threshold, it indicates that the position is further away from the center of the light spot, and the selected vertical direction is reversed. Therefore, the worktable should be controlled to move two more steps in the opposite vertical direction of the movement direction of this step, that is, the opposite of the vertical direction of S1022 (for example, if S1022 is a 90-degree clockwise rotation, S1024 is a 90-degree counterclockwise rotation), and it should be confirmed that the first optical energy sensor has entered the target range of the light spot. Here, the target range is smaller than the complete range of the light spot.

[0039] Please refer to Figures 3(a) and (b), which illustrate a schematic diagram of a spiral search process provided in an embodiment of this application. As shown in Figures 3(a) and (b), the spiral search can be performed in a clockwise direction or a counterclockwise direction. The spiral movement starts from position "0", with a side length of L for the square light spot, and a step size of L / 4 each time.

[0040] When the light position is first detected at position "1", that is, when the light intensity ratio at position "1" is greater than the first preset threshold for the first time, move one more step in the same direction to position "2". If the light intensity ratio at position "2" is still greater than the first preset threshold, move one more step in the direction perpendicular to the previous movement direction.

[0041] For Figure 3(a), if a 90-degree clockwise rotation is selected, the light intensity ratio is still greater than the first preset threshold, and the first optical energy sensor has entered the target range of the light spot. The position "3" that it has moved to can be determined as the first position.

[0042] For Figure 3(b), if a 90-degree clockwise rotation is selected, but the moved position "S" is further away from the center of the light spot, and the light intensity ratio is less than the first preset threshold, then move two more steps in the opposite perpendicular direction of the previous step. The moved position "3" can then be determined as the first position. It should be noted that the broken line between position "S" and position "3" in Figure 3(b) is drawn to distinguish the lines and does not represent the actual movement trajectory. The actual movement trajectory from position "S" to position "3" should be a straight line moving vertically upwards for two steps.

[0043] This comprehensive spiral search strategy enables reliable positioning within the projected light spot on the workpiece table, regardless of the initial working condition, once the light position is detected in any direction or position. Furthermore, after the initial light position is detected, a search strategy involving one step in the same direction, one step in a different direction, and two steps in the opposite direction ensures that the determined initial position is closer to the center of the light spot, avoiding the need for another large-scale spiral movement and thus accelerating the search and positioning speed.

[0044] Furthermore, in step S1024, after controlling the worktable to move two more steps in the opposite perpendicular direction to the direction of movement of the previous step, step S102 may also include: Determine whether the light intensity ratio is still greater than the first preset threshold; if it is still greater than or equal to the first preset threshold, determine that the first optical energy sensor has entered the target range of the light spot; if it is less than the first preset threshold, control the worktable to move again in a spiral manner from the current position, and re-determine whether the first optical energy sensor has entered the target range of the light spot according to the light intensity ratio at each corresponding position.

[0045] To reliably locate a position within the light spot and avoid situations where an unreasonable step size setting causes the sensor to move two steps in the opposite vertical direction and then exceed the light spot's range, the light intensity ratio can be re-determined to see if it is still greater than the first preset threshold. If it is still greater than or equal to the first preset threshold, it is determined that the first optical energy sensor has entered the target range of the light spot. If it is less than the first preset threshold, the stage is controlled to move from its current position in a spiral motion, and the determination of whether the first optical energy sensor has entered the target range of the light spot is made again in the aforementioned manner.

[0046] S103. If the position has been entered, record the first position of the first optical energy sensor and control the worktable to stop moving.

[0047] S104. Starting from the first position, control the worktable to perform line scanning along the coordinate axis direction of the plane, and determine the edge position of the light spot according to the light intensity ratio during the line scanning process.

[0048] In this step, the edge position of the light spot can be understood as the light-dark transition position, where the light intensity ratio is a first preset ratio (approximately 50%). Therefore, starting from the first position, the worktable is controlled to perform a line scan along the coordinate axis direction of the plane, which can find the light-dark or dark-light gradient line. By stepping around the 50% light-dark transition position, the edge position of the light spot is determined. The coordinate axes along the plane of the worktable include the X-axis and Y-axis, and the coordinate axis direction includes at least the positive and negative directions of each coordinate axis, such as the positive and negative X-axis directions.

[0049] In another possible implementation, to speed up the search, this embodiment uses a binary search strategy, then step S104 may include: S1041. For any direction of any coordinate axis, taking the first position as the starting point, control the worktable to perform line scanning along that direction to determine the light intensity ratio corresponding to a position point that is a predetermined distance away from the starting point.

[0050] The predetermined length is greater than the length of the light spot in that direction to ensure that the edge of the light spot exists within the predetermined length. It should be noted that line scanning here can be understood as linear, continuous linear motion, not continuous detection, such as continuous measurement of light intensity. That is, the stage is controlled to move along this direction in a straight line to a position a predetermined length away from the starting point, and the light intensity at the starting point and the position is obtained respectively, thereby determining the light intensity ratio corresponding to the starting point and the position.

[0051] S1042. Iteratively select a position point between the position point and the starting point according to the binary search strategy until the edge position of the light spot in this direction is determined according to the light intensity ratio corresponding to the selected position point.

[0052] The binary search strategy iteratively selects location points and compares the light intensity ratio of the selected location points with the first preset ratio of the edge location, halving the search range each time until the edge location of the light spot in that direction is found.

[0053] In specific implementation, step S1042 may include: Step 1: For any selected location point, determine whether the light intensity ratio corresponding to that location point is equal to the first preset ratio.

[0054] Step 2: If equal to, then the position point is determined as the edge position of the light spot in that direction.

[0055] Here, the first preset ratio can be determined through a prior reference experiment, that is, the light intensity ratio at the edge position is determined as the first preset ratio based on the prior reference experiment. If the light intensity ratio corresponding to any selected position point is equal to the first preset ratio, then that position point is directly determined as the edge position of the light spot in that direction.

[0056] Step 3: If not equal, determine whether the distance between the location point and the endpoint of the interval corresponding to the binary search strategy is less than or equal to the preset location precision.

[0057] If the light intensity ratio corresponding to any selected location point is not equal to the first preset ratio, the light intensity ratio of that location point can be compared with the two endpoints in the previous round of binary search (that is, the midpoint of the line connecting the two endpoints in the previous round of binary search is that location point). Generally speaking, in the interval where the edge location is located, the light intensity ratio of the two endpoints should be greater than the first preset ratio and less than the first preset ratio.

[0058] Therefore, one endpoint can be selected from the two endpoints in the previous round of binary search as the interval endpoint corresponding to the binary search strategy in the next round; then, the distance between the position point and the interval endpoint corresponding to the binary search strategy in the next round is determined, and it is judged whether this distance is less than or equal to the preset position accuracy.

[0059] Step 4: If the position is less than or equal to the preset position accuracy, then determine the edge position of the light spot in that direction based on the position point and the corresponding interval endpoint.

[0060] If this distance is less than or equal to the preset position accuracy, an edge position point can be determined by interpolation between the position point and the corresponding interval endpoint, and the binary search can be stopped.

[0061] Step 5: If the position accuracy is greater than the preset position accuracy, then continue to iterate and select the next position point between the current position point and the corresponding interval endpoint according to the binary search strategy.

[0062] If this distance is greater than the preset position accuracy, the root binary search strategy continues to iterate between the current position and the corresponding interval endpoint to select the next position, and then returns to execute step 1 above.

[0063] Please see Figure 4 , Figure 4 A schematic diagram of a binary search process provided in an embodiment of this application is shown. Figure 4 As shown, taking the negative X-axis direction as an example, A0 is the starting point located in the aforementioned steps, and A1 is the position point at a predetermined distance (e.g., 1.5 times the side length) from the starting point. Using a binary search strategy, A2 is inserted between A1 and A0 in the first search, A3 between A2 and A0 in the second search, A4 between A3 and A2 in the third search, and so on, until the nth search determines the edge position A5 of the light spot in that direction.

[0064] Using a similar method, the edge positions of the light spot in each direction can be determined, that is, the edge positions of the four sides of the square light spot.

[0065] S105. Locate the center of the light spot based on the edge position of the light spot.

[0066] In this step, the center of the light spot can be located through geometric calculation based on the edge positions of the light spot in various directions.

[0067] Please see Figure 5 , Figure 5 A schematic diagram of a beam center positioning method provided in an embodiment of this application is shown. Figure 5 As shown, the scan along the X and Y axes uses a binary search: Step 1: X-axis scanning. The distance between the starting position A1 and A0 on the X-axis is 1.5Lx, and the distance between the ending positions A1 and A6 on the X-axis is 3Lx. The 50% light-dark transition positions on the X-axis are determined through X-axis scanning, i.e., points A5 and A7 in the diagram. The X-center position A8 can be calculated using points A5 and A7.

[0068] Step 2: Y-axis scanning. Determine the starting position B1 and ending position B2 of the Y-axis, with a distance of 3Ly between B1 and B2. Use the Y-axis scanning to determine the 50% light / dark transition positions on the Y-axis, i.e., points B3 and B4 in the diagram. The Y-center position, which is the center of the light spot M, can be calculated using points B3 and B4.

[0069] Furthermore, after determining the center of the light spot, the positioning method also includes: S105. Control the worktable to perform a line scan again along the coordinate axis direction of the plane to determine the second position of the first optical energy sensor when the light intensity ratio is a second preset ratio.

[0070] S106. Control the worktable to perform step scanning along the Z-axis direction; wherein, the Z-axis is perpendicular to the plane where the worktable is located; whenever the worktable moves one step, determine the light intensity ratio between the first light intensity detected by the first optical energy sensor at the second position and the second light intensity detected by the second optical energy sensor.

[0071] S107. Determine the focal plane of the positioning system based on the Z-axis positions to which the worktable has moved and the corresponding light intensity ratios.

[0072] For steps S105 to S107, please refer to Figure 6 , Figure 6 A schematic diagram illustrating the positional relationship between energy and the focal plane, provided in an embodiment of this application, is shown. Figure 6 As shown, when scanning along the vertical line (Z-axis) from the starting plane of the scan, the position with 25% energy (i.e., the light intensity ratio is the second preset ratio of 25%) is taken as the second position. The relationship between the vertical position of this position and the energy is parabolic, and the focal plane is located at the endpoint of the parabola, i.e. the point of lowest energy.

[0073] For example, the second preset ratio is set to 25%, and a line scan is performed again along the coordinate axis of the plane to determine the second position of the first optical energy sensor when the light intensity ratio is 25%. The method of finding the 25% light intensity ratio by line scan can be referred to the above method, and will not be repeated here.

[0074] Then, the control table performs step scanning along the Z-axis. Each time the table moves one step along the Z-axis, the intensity ratio between the first light intensity detected by the first optical energy sensor and the second light intensity detected by the second optical energy sensor at the second position is determined.

[0075] Finally, based on the Z-axis positions moved by the worktable and the corresponding light intensity ratios, the Z-axis position with the lowest energy can be determined, which is the focal plane of the positioning system.

[0076] In one possible implementation, step S106 may include: S1061. Control the worktable to perform the first step scan along the Z-axis direction according to the first step length.

[0077] S1062. Determine the first Z-axis position based on the light intensity ratio of each Z-axis position scanned during the first step of the scanning process.

[0078] S1063. Perform a second step scan with a second step size within a predetermined range around the first Z-axis position.

[0079] Wherein, the second step length is smaller than the first step length. This application embodiment employs a method combining coarse scanning (first step scan) and fine scanning (second step scan). First, a coarse scan is used to roughly locate the first Z-axis position, and then a fine scan is performed near the first Z-axis position.

[0080] In one possible implementation, step S1062 may include: When the light intensity ratio corresponding to any Z-axis position is less than the second preset threshold, the Z-axis position is determined as the first Z-axis position; when the light intensity ratio corresponding to each Z-axis position is greater than or equal to the second preset threshold, a first function between the Z-axis position and the light intensity ratio is fitted according to each Z-axis position and the corresponding light intensity ratio; wherein, the first function is in the form of a parabola; the Z-axis position corresponding to the minimum value of the first function is determined as the first Z-axis position.

[0081] For example, the second preset threshold can be 1%. During the scanning process, a coarse scan is first performed along the Z-axis with a step of 50 μm. If a point with an energy ratio below 1% exists, the focal plane is located near the center point of the interval where the energy ratio is below 1%; the center point of the interval where the energy ratio is below 1% is determined as the first Z-axis position. Alternatively, if no point with an energy ratio below 1% exists, a first function relating the Z-axis position and the light intensity ratio is fitted, and the Z-axis position corresponding to the minimum value of the first function is determined as the first Z-axis position. Then, a fine scan is performed within the Z-axis range of -50 μm to 50 μm at that point, with measurements taken along the Z-axis in 2 μm steps.

[0082] Alternatively, the Z-axis can be moved to the vicinity of the first Z-axis position and a coarse scan can be performed again. If there is no point with an energy ratio lower than 1%, then the minimum point of the parabola will be searched, and the position of the first Z-axis will be redefined.

[0083] In one possible implementation, step S107 may include: Based on the Z-axis positions and corresponding light intensity ratios scanned during the second step scanning process, a second function relating the Z-axis position and the light intensity ratio is fitted; wherein the second function is in parabolic form; the Z-axis position corresponding to the minimum value of the second function is determined as the focal plane position of the positioning system.

[0084] S108. Move the worktable to the focal plane and reposition the center of the light spot.

[0085] In this way, by repositioning the center of the light spot on the focal plane, the measurement data will be more accurate. The repositioning steps can refer to the aforementioned steps S101 to S105 and achieve the same technical effect, so they will not be repeated here.

[0086] After the center of the light spot is located, the deviation between the light spot center and the nominal optical axis of the objective lens can be used to compensate for the actual installation position of the first optical energy sensor, providing accurate input for subsequent optical system calibration. Once the position of the first optical energy sensor is determined, the diameter of the sensor's optical aperture can be measured, ultimately determining the position of the workpiece stage coordinate system relative to the objective lens's optical axis.

[0087] In one experiment, the spot center positioning method provided in this application embodiment was applied to the objective lens optical axis position calibration test. Figures 7(a) to (c) show the experimental results of spot center positioning provided in this application embodiment. Figure 7(a) shows the experimental results of spiral search, Figure 7(b) shows the experimental results of binary search and spot center positioning, and Figure 7(c) shows the experimental results of focal plane fitting. The experimental results show that the positioning method can achieve fast, accurate, and fully automatic spot center positioning.

[0088] Based on the same inventive concept, this application also provides a positioning system for the center of a light spot; the positioning system includes: a controller, a first optical energy sensor, a second optical energy sensor, a worktable, and a light source; The light source projects a light spot onto the worktable; the first optical energy sensor is mounted on the worktable to detect the light intensity on the worktable surface; the second optical energy sensor is used to detect the light intensity of the light source; and the controller is used to execute the steps of the above-described method for locating the center of the light spot.

[0089] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 8 As shown, the electronic device 800 includes a processor 810, a memory 820, and a bus 830.

[0090] The memory 820 stores machine-readable instructions that can be executed by the processor 810. When the electronic device 800 is running, the processor 810 and the memory 820 communicate via the bus 830. When the machine-readable instructions are executed by the processor 810, the steps of the spot center positioning method as described in the above method embodiment can be performed. For specific implementation details, please refer to the method embodiment, which will not be repeated here.

[0091] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can perform the above-described actions. Figure 1 The steps of the spot center positioning method in the method embodiment can be found in the method embodiment for specific implementation, and will not be repeated here.

[0092] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0093] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0094] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0095] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0096] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0097] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered 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.

Claims

1. A method for locating the center of a light spot, characterized in that, A controller is used in a positioning system for the center of a light spot. The positioning system also includes a first optical energy sensor, a second optical energy sensor, a worktable, and a light source. The light source projects a light spot onto the worktable. The first optical energy sensor is mounted on the worktable and is used to detect the light intensity on the surface of the worktable. The second optical energy sensor is used to detect the light intensity of the light source; the positioning method includes: The worktable is controlled to move in a spiral manner; wherein, each time the worktable moves one step, the light intensity ratio between the first light intensity detected at the location of the first optical energy sensor and the second light intensity detected by the second optical energy sensor is determined. Based on the light intensity ratio at each corresponding position, determine whether the first optical energy sensor has entered the target range of the light spot; If the first position of the first optical energy sensor has been entered, the first position of the first optical energy sensor is recorded and the worktable is controlled to stop moving. Starting from the first position, the worktable is controlled to perform line scanning along the coordinate axis direction of the plane, and the edge position of the light spot is determined according to the light intensity ratio during the line scanning process. The center of the light spot is located based on the edge position of the light spot.

2. The positioning method according to claim 1, characterized in that, The positioning method further includes: The worktable is controlled to perform a line scan again along the coordinate axis of the plane to determine the second position of the first optical energy sensor when the light intensity ratio is a second preset ratio. The worktable is controlled to perform step scanning along the Z-axis direction; wherein the Z-axis is perpendicular to the plane where the worktable is located; each time the worktable moves one step, the light intensity ratio between the first light intensity detected by the first optical energy sensor at the second position and the second light intensity detected by the second optical energy sensor is determined; The focal plane of the positioning system is determined based on the Z-axis positions to which the worktable moves and the corresponding light intensity ratios. Move the worktable to the focal plane and reposition the center of the light spot.

3. The positioning method according to claim 1, characterized in that, The step of determining whether the first optical energy sensor has entered the target range of the light spot based on the light intensity ratio at each corresponding position includes: When the light intensity ratio at any step is greater than the first preset threshold, the worktable is controlled to move another step in the direction of that step, and it is determined whether the light intensity ratio is still greater than or equal to the first preset threshold. If it is still greater than or equal to the first preset threshold, then control the worktable to move one step again in the direction perpendicular to the movement direction of this step, and determine whether the light intensity ratio is still greater than the first preset threshold. If it is still greater than or equal to the first preset threshold, then it is determined that the first optical energy sensor has entered the target range of the light spot; If the value is less than the first preset threshold, the worktable is controlled to move two steps again in the opposite vertical direction to the movement direction of that step, and it is determined that the first optical energy sensor has entered the target range of the light spot.

4. The positioning method according to claim 3, characterized in that, After controlling the worktable to move two more steps in the opposite perpendicular direction to the movement direction of the previous step, the step of determining whether the first optical energy sensor has entered the target range of the light spot based on the light intensity ratio at the corresponding position of each step further includes: Determine whether the light intensity ratio is still greater than the first preset threshold; If it is still greater than or equal to the first preset threshold, then it is determined that the first optical energy sensor has entered the target range of the light spot; If the light intensity is less than the first preset threshold, the worktable is controlled to move again in a spiral manner from its current position, and the first optical energy sensor is re-determined whether it has entered the target range of the light spot based on the light intensity ratio at each corresponding position.

5. The positioning method according to claim 1, characterized in that, Starting from the first position, the worktable is controlled to perform a line scan along the coordinate axis of the plane, and the edge position of the light spot is determined according to the light intensity ratio during the line scan, including: For any direction of any coordinate axis, starting from the first position, the worktable is controlled to perform a line scan along that direction to determine the light intensity ratio corresponding to a position point at a predetermined distance from the starting point; wherein, the predetermined length is greater than the length of the light spot in that direction; The position point is iteratively selected between the position point and the starting point according to the binary search strategy until the edge position of the light spot in this direction is determined according to the light intensity ratio corresponding to the selected position point.

6. The positioning method according to claim 5, characterized in that, The position point is iteratively selected between the current position point and the starting point using a binary search strategy until the edge position of the light spot in this direction is determined based on the light intensity ratio corresponding to the selected position point, including: For any selected location point, determine whether the light intensity ratio corresponding to that location point is equal to the first preset ratio; If equal, then that location is determined as the edge position of the light spot in that direction; If not equal, then determine whether the distance between the location point and the interval endpoint corresponding to the binary search strategy is less than or equal to the preset location precision; If the position is less than or equal to the preset position accuracy, the edge position of the light spot in that direction is determined based on the position point and the corresponding interval endpoint. If the accuracy is greater than the preset position precision, then the next position point is selected iteratively between the current position point and the corresponding interval endpoint according to the binary search strategy.

7. The positioning method according to claim 2, characterized in that, Controlling the worktable to perform step scanning along the Z-axis includes: The worktable is controlled to perform the first step scan along the Z-axis with a first step length; The first Z-axis position is determined based on the light intensity ratio of each Z-axis position scanned during the first step of the scanning process; A second step scan is performed within a predetermined range around the first Z-axis position with a second step size; the second step size is smaller than the first step size.

8. The positioning method according to claim 7, characterized in that, The focal plane of the positioning system is determined based on the Z-axis positions of the worktable and the corresponding light intensity ratios, including: Based on the Z-axis positions and corresponding light intensity ratios scanned during the second step scan, a second function relating the Z-axis positions and light intensity ratios is fitted; wherein, the second function is in the form of a parabola. The Z-axis position corresponding to the minimum value of the second function is determined as the location of the focal plane of the positioning system.

9. The positioning method according to claim 7, characterized in that, The first Z-axis position is determined based on the light intensity ratio corresponding to each Z-axis position scanned during the first step of the scanning process, including: When the light intensity ratio corresponding to any Z-axis position is less than the second preset threshold, the Z-axis position is determined as the first Z-axis position. When the light intensity ratio corresponding to each Z-axis position is greater than or equal to the second preset threshold, a first function between the Z-axis position and the light intensity ratio is fitted based on each Z-axis position and the corresponding light intensity ratio; wherein, the first function is in the form of a parabola; The Z-axis position corresponding to the minimum value of the first function is determined as the first Z-axis position.

10. A system for locating the center of a light spot, characterized in that, The positioning system includes: a controller, a first optical energy sensor, a second optical energy sensor, a worktable, and a light source; The light source projects a light spot onto the worktable; the first optical energy sensor is mounted on the worktable and is used to detect the light intensity on the surface of the worktable; the second optical energy sensor is used to detect the light intensity of the light source; the controller is used to execute the steps of the spot center positioning method as described in any one of claims 1 to 9.

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