A method and device for calibrating a horizontal zero position of a mask table, and an electronic device

Abstract

This application provides a method, apparatus, and electronic device for calibrating the horizontal zero position of a mask stage, including: controlling a movable stage to perform a spiral search to align an image alignment mark with a grating image, and recording the alignment position corresponding to the movable stage; constructing a loss function based on the grating group position of the grating image corresponding to each measurement on the mask stage, the mark position of the image alignment mark on the movable stage, the alignment position of the movable stage obtained in each measurement, and the horizontal zero position deviation of the mask stage; iteratively calculating the loss function using the gradient descent method to determine the target horizontal zero position deviation of the mask stage; and completing the calibration of the horizontal zero position of the mask stage based on the nominal zero position and the target horizontal zero position deviation. This application calibrates the horizontal zero position of the mask stage by using a mask stage reference plate and a workpiece stage reference plate, simplifying the calibration steps, reducing calibration costs, and improving calibration efficiency.

Description

Technical Field

[0001] This application relates to the field of optical inspection technology, and in particular to a method, apparatus and electronic device for calibrating the horizontal zero position of a mask stage. Background Technology

[0002] As the production accuracy requirements of measurement equipment continue to increase, the early calibration of equipment hardware is very important. In order to improve the overlay accuracy between layers, it is necessary to establish the positional relationship between the mask and the wafer. Therefore, it is necessary to determine the calibration of the zero position of the mask stage.

[0003] Currently, the calibration of the horizontal zero position of the mask stage usually requires removing the outer protective cover of the equipment, inserting a pin into a fixed round hole on the mask stage, and then pressing a specially made mask plate against the pin. Measurement is then performed using the small holes on the mask plate. However, in actual calibration, removing the outer protective cover and installing the pin each time is quite cumbersome, resulting in low efficiency in the calibration process. Furthermore, different sizes of mask stages require custom-made corresponding Dev mask plates, increasing calibration costs. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide at least one method, apparatus and electronic device for calibrating the horizontal zero position of the mask stage, which calibrates the horizontal zero position of the mask stage by using a mask stage reference plate and a workpiece stage reference plate, thereby simplifying the calibration steps, reducing calibration costs and improving calibration efficiency.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, embodiments of this application provide a method for calibrating the horizontal zero position of a mask stage, applied to a measurement system. The measurement system includes a light source, a mask stage, an objective lens, and a movable stage. A mask reference plate is fixed on the mask stage, and multiple grating groups are formed on the mask reference plate. A stage reference plate is fixed on the movable stage, and image alignment marks are formed on the stage reference plate. The method includes: turning on the light source, the light emitted by the light source passing through the multiple grating groups and the objective lens to form a grating image corresponding to each grating group on the stage reference plate; controlling the movable stage to move to perform multiple measurements, wherein during each measurement: controlling... A movable stage is used for spiral search to align the image alignment mark with a grating image, and the alignment position corresponding to the movable stage is recorded. Based on the position of the grating group to which the grating image belongs on the mask stage, the mark position of the image alignment mark on the movable stage, the alignment position of the movable stage obtained in each measurement, and the horizontal zero-position deviation of the mask stage, a loss function is constructed. The loss function is iteratively calculated using the gradient descent method to determine the target horizontal zero-position deviation of the mask stage. Based on the nominal zero position and the target horizontal zero-position deviation of the mask stage, the horizontal zero position of the mask stage is calibrated.

[0007] In one possible implementation, each grating group includes an X-direction grating and a Y-direction grating, image alignment marks include X-direction alignment marks and Y-direction alignment marks, grating images include X-direction grating images and Y-direction grating images, and alignment positions include X-alignment coordinates and Y-alignment coordinates corresponding to the movable stage. The alignment position of the movable stage in each measurement process is determined as follows: during the measurement process, the following processing is performed: controlling the light source to move above the target grating group to form X-direction grating images and Y-direction grating images on the stage reference plate; controlling the movable stage to perform a spiral search according to a preset unit step size; for each preset unit step size, acquiring the X-direction grating overlap rate between the X-direction grating image fed back by the X-direction alignment mark and the X-direction alignment mark, and the Y-direction grating overlap rate between the Y-direction grating image fed back by the Y-direction alignment mark and the Y-direction alignment mark; and determining the X-alignment coordinates and Y-alignment coordinates corresponding to each measurement based on the X-direction grating overlap rate and Y-direction grating overlap rate corresponding to each movement of the movable stage.

[0008] In one possible implementation, the X and Y alignment coordinates of the movable stage during each measurement are determined as follows: during the measurement process, the X coordinate of the movable stage corresponding to the maximum X-direction grating overlap rate is determined as the X alignment coordinate; the Y coordinate of the movable stage corresponding to the maximum Y-direction grating overlap rate is determined as the Y alignment coordinate.

[0009] In one possible implementation, the grating group position includes the X coordinate of the X-direction grating on the mask stage and the Y coordinate of the Y-direction grating on the mask stage; the horizontal zero-position deviation includes the X-direction zero-position deviation, Y-direction zero-position deviation, and rotation angle zero-position deviation of the nominal zero position relative to the actual zero position on the mask stage; the marker position includes the X coordinate of the X-direction alignment mark on the movable worktable and the Y coordinate of the Y-direction alignment mark on the movable worktable; wherein, the loss function is constructed using the following formula:

[0010]

[0011] In this formula, F(.) represents the loss function, n represents the total number of measurements, Rz0 is the zero-position deviation of the rotation angle, and x pi The x-coordinate of the X-direction grating on the mask stage corresponding to the i-th measurement is y. pi This represents the Y-coordinate of the Y-direction grating on the mask stage corresponding to the i-th measurement; x0 is the zero-position deviation in the X direction, y0 is the zero-position deviation in the Y direction, and x... g This indicates the X-coordinate of the alignment mark on the movable worktable, and the y-coordinate... g This indicates the Y-coordinate of the alignment mark on the movable worktable, x siThe x-coordinate corresponds to the i-th measurement, and the y-coordinate corresponds to the y-coordinate. si This represents the Y-alignment coordinate corresponding to the i-th measurement.

[0012] In one possible implementation, the step of using gradient descent to iteratively calculate the loss function and determine the target horizontal zero-position deviation corresponding to the mask stage includes: (A) determining the first partial derivative expression of the loss function with respect to the zero-position deviation in the X direction, the second partial derivative expression with respect to the zero-position deviation in the Y direction, and the third partial derivative expression with respect to the zero-position deviation in the rotation angle; (B) substituting the current zero-position deviation in the X direction, the current zero-position deviation in the Y direction, and the current zero-position deviation in the rotation angle into the first, second, and third partial derivative expressions respectively to obtain the X partial derivative value corresponding to the first partial derivative expression, the Y partial derivative value corresponding to the second partial derivative expression, and the rotation angle partial derivative value corresponding to the third partial derivative expression; (C) updating the zero-position deviation in the X direction, the Y direction, and the rotation angle based on the calculated X partial derivative value, Y partial derivative value, and rotation angle partial derivative value respectively; (D) substituting the updated X-direction zero-position deviation, Y-direction zero-position deviation, and rotation angle zero-position deviation into the loss function to calculate the loss value; (E) comparing the loss value with a preset loss threshold and determining the target horizontal zero-position deviation based on the comparison result.

[0013] In one possible implementation, step (C) includes: calculating a first product between the X-direction partial derivative and the mask stage unit step size, and determining the sum of the first product and the current X-direction zero deviation as the updated X-direction zero deviation; calculating a second product between the Y-direction partial derivative and the mask stage unit step size, and determining the sum of the second product and the current Y-direction zero deviation as the updated Y-direction zero deviation; calculating a third product between the rotation angle partial derivative and the mask stage unit step size, and determining the sum of the third product and the current rotation angle zero deviation as the updated rotation angle zero deviation.

[0014] In one possible implementation, the target horizontal zero-position deviation includes the target X-direction zero-position deviation, the target Y-direction zero-position deviation, and the target rotation angle zero-position deviation. Step (E) includes: if the loss value is greater than or equal to a preset loss threshold, then using the updated X-position deviation, Y-direction deviation, and rotation angle deviation, returning to step (B); if the loss value is less than the preset loss threshold, then the updated X-position zero-position deviation, Y-direction zero-position deviation, and rotation angle zero-position deviation are respectively determined as the target X-position zero-position deviation, the target Y-direction zero-position deviation, and the target rotation angle zero-position deviation.

[0015] In one possible implementation, the nominal zero position includes a nominal zero position X coordinate, a nominal zero position Y coordinate, and a nominal zero position rotation angle. The step of calibrating the horizontal zero position of the mask stage based on the deviation between the nominal zero position and the target horizontal zero position includes: determining the difference between the nominal zero position X coordinate and the target X-direction zero position deviation as the actual zero position X coordinate corresponding to the mask stage; determining the difference between the nominal zero position Y coordinate and the target Y-direction zero position deviation as the actual zero position Y coordinate corresponding to the mask stage; determining the difference between the nominal zero position rotation angle and the target rotation angle zero position deviation as the actual zero position rotation angle corresponding to the mask stage; and controlling the mask stage to move to the position indicated by the actual zero position X coordinate, actual zero position Y coordinate, and actual zero position rotation angle to complete the calibration of the horizontal zero position of the mask stage.

[0016] Secondly, this application also provides a calibration device for the horizontal zero position of a mask stage, applied to a measurement system. The measurement system includes a light source, a mask stage, an objective lens, and a movable stage. A mask reference plate is fixed on the mask stage, and multiple grating groups are formed on the mask reference plate. A stage reference plate is fixed on the movable stage, and image alignment marks are formed on the stage reference plate. The device includes: a projection module for turning on the light source, the light emitted by the light source passing through multiple grating groups and the objective lens to form a grating image corresponding to each grating group on the stage reference plate; and a measurement module for controlling the movement of the movable stage to perform multiple measurements. During each measurement process: the movable stage is controlled to move. The movable stage performs a spiral search to align the image alignment mark with a grating image and records the alignment position corresponding to the movable stage. The loss function construction module is used to construct the loss function based on the grating group position on the mask stage used in each measurement, the mark position of the image alignment mark on the movable stage, the alignment position of the movable stage obtained in each measurement, and the horizontal zero-position deviation of the mask stage. The determination module uses the gradient descent method to iteratively calculate the loss function and determine the target horizontal zero-position deviation of the mask stage. The calibration module is used to calibrate the horizontal zero position of the mask stage based on the nominal zero position and the target horizontal zero-position deviation of the mask stage.

[0017] Thirdly, embodiments of this application also provide an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the memory communicate via the bus. The machine-readable instructions are executed by the processor to perform the steps of the mask stage horizontal zero-position calibration method in the first aspect or any possible implementation of the first aspect.

[0018] The mask stage horizontal zero-position calibration method, apparatus, and electronic equipment provided in this application control a movable stage to perform a spiral search, aligning the grating image with the image alignment mark, and recording the alignment position corresponding to the movable stage. Based on the grating group position on the mask stage used in each measurement, the mark position of the image alignment mark on the movable stage, the alignment position of the movable stage obtained in each measurement, and the horizontal zero-position deviation of the mask stage, a loss function is constructed. The loss function is iteratively calculated using the gradient descent method to determine the target horizontal zero-position deviation of the mask stage. The horizontal zero-position of the mask stage is calibrated based on the nominal zero-position and the target horizontal zero-position deviation. This application calibrates the horizontal zero-position of the mask stage by using a mask stage reference plate and a workpiece stage reference plate, eliminating the need to disassemble external protection and load a special mask plate, simplifying the calibration steps and reducing calibration costs.

[0019] The advantages of this application are:

[0020] Measurements are taken using a mask stage reference plate and a workpiece stage reference plate, without the need to disassemble or install external protection or load a special mask. This avoids the tediousness of measurement and calibration and reduces the cost of making a special mask.

[0021] The zero-position deviation of the mask stage can be determined simply by aligning the marks on the two reference plates, which is convenient and quick.

[0022] 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

[0023] 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.

[0024] Figure 1 A schematic diagram of the structure of a measurement system provided in an embodiment of this application is shown;

[0025] Figure 2 This illustration shows a structural schematic diagram of the position of a mask reference plate relative to a mask stage, provided in an embodiment of this application.

[0026] Figure 3 A flowchart is shown for a method for calibrating the horizontal zero position of a mask stage according to an embodiment of this application;

[0027] Figure 4A schematic diagram of a movable workbench performing a spiral search, provided in an embodiment of this application, is shown.

[0028] Figure 5 A flowchart illustrating the steps of a method for determining the zero deviation of a target level according to an embodiment of this application is shown.

[0029] Figure 6 This illustration shows a structural schematic diagram of a calibration device for the horizontal zero position of a mask stage provided in an embodiment of this application;

[0030] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0031] 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. It should be understood that the drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0032] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically 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 to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] Currently, the calibration of the mask stage's horizontal zero position usually requires removing the equipment's external protection, inserting a pin into a fixed round hole on the mask stage, then pressing a specially made mask plate against the pin, and using the small holes on the mask plate for measurement.

[0034] However, in actual calibration, removing the equipment's external protection and installing pins each time is cumbersome, leading to low calibration efficiency. Furthermore, the original calibration method has the following drawbacks:

[0035] ① The accuracy of the mask position depends heavily on the position of the pins;

[0036] ② Manually uploading the mask plate will increase the risk of mask plate wear, increase calibration costs, and affect calibration accuracy;

[0037] ③ Because the size of the apertures in the photomask that are mapped onto the wafer surface is extremely small, they are difficult to locate.

[0038] Increased calibration time reduces calibration efficiency.

[0039] Based on this, embodiments of this application provide a method, apparatus, and electronic device for calibrating the horizontal zero position of a mask stage. By using a mask stage reference plate and a workpiece stage reference plate, the horizontal zero position of the mask stage is calibrated, simplifying the calibration steps, reducing calibration costs, and improving calibration efficiency. Specifically, as follows:

[0040] Please see Figure 1 , Figure 1 A schematic diagram of a measurement system provided in an embodiment of this application is shown. Please refer to [link / reference]. Figure 2 , Figure 2 This illustration shows a structural schematic diagram of the position of a mask reference plate relative to a mask stage, provided in an embodiment of this application.

[0041] like Figure 1 As shown, the measurement system includes a light source 1, a mask stage 2, an objective lens 3, and a movable stage 4. A mask reference plate 5 is fixed on the mask stage 2, as shown. Figure 2 As shown, the length of the mask reference plate 5 is less than the length of the mask stage 2, and the width of the mask reference plate 5 is less than the width of the mask stage 2. Multiple grating groups a1 to a2 are formed on the mask reference plate. n n represents the number of grating groups. A worktable reference plate (not shown in the figure) is fixed on the movable worktable 4, and image alignment marks are formed on the worktable reference plate.

[0042] Please see Figure 3 , Figure 3 This document illustrates a flowchart of a method for calibrating the horizontal zero point of a mask stage according to an embodiment of this application. The method for calibrating the horizontal zero point of a mask stage provided in this embodiment of the application is as follows: Figure 3 As shown, it includes the following steps:

[0043] S100, Turn on the light source.

[0044] The light emitted by the light source 1 passes through multiple grating groups a on the mask reference plate 5 and the objective lens 3 to form a grating image corresponding to each grating group a on the stage reference plate.

[0045] S200: Control the movable stage to move to perform multiple measurements. During each measurement: control the movable stage to perform a spiral search so that the image alignment mark is aligned with a raster image, and record the corresponding alignment position of the movable stage.

[0046] S300. Based on the position of the grating group to which the grating image belongs in each measurement on the mask stage, the position of the image alignment mark on the movable worktable, the alignment position of the movable worktable obtained in each measurement, and the horizontal zero deviation of the mask stage, construct a loss function.

[0047] S400. Use the gradient descent method to iteratively calculate the loss function and determine the target horizontal zero-position deviation corresponding to the mask stage.

[0048] S500. Based on the deviation between the nominal zero position and the target horizontal zero position of the mask stage, complete the calibration of the horizontal zero position of the mask stage.

[0049] In specific implementation, each grating group a includes an X-direction grating and a Y-direction grating, the image alignment marks include X-direction alignment marks and Y-direction alignment marks, and the grating image includes an X-direction grating image and a Y-direction grating image, such as... Figure 1 As shown, with grating group a k For example, after light source 1 is turned on, the light emitted by light source 1 passes through grating group a. k The X-direction grating and objective lens 3 form an X-direction grating image on the stage reference plate. The light emitted by the light source 1 passes through the grating group a. k The Y-direction grating and objective lens 3 form a Y-direction grating image on the worktable reference plate. The alignment position includes the X alignment coordinate and Y alignment coordinate corresponding to the movable worktable. In this application, the grating image corresponding to the grating group can be selected to perform the measurement according to actual needs. For example, the two grating groups that are farthest apart on the mask reference plate can be selected to perform two measurements to complete the calibration.

[0050] In this application, before step S200, it is necessary to control the mask stage to move to the initial position corresponding to the nominal zero position of the mask stage, and then execute step S200.

[0051] In a preferred embodiment, the alignment position of the movable stage for each measurement process is determined by performing the following steps during that measurement process:

[0052] The movable stage is controlled to perform a spiral search according to a preset unit step size. After each preset unit step size, the X-direction grating overlap rate between the X-direction alignment mark and the X-direction alignment mark is acquired, as well as the Y-direction grating overlap rate between the Y-direction alignment mark and the Y-direction alignment mark. Based on the X-direction grating overlap rate and Y-direction grating overlap rate corresponding to each movement of the movable stage, the X-alignment coordinates and Y-alignment coordinates corresponding to this measurement are determined.

[0053] In this application, both the X-direction alignment mark and the Y-direction alignment mark are equipped with brightness sensors to obtain the grating overlap rate between the grating image passed through the objective lens and the alignment mark. (See also...) Figure 4 , Figure 4 This diagram illustrates a movable workbench performing a spiral search, as provided in an embodiment of this application. Figure 4 As shown, the movable worktable starts from the preset initial position 0 and performs a spiral search along the horizontal XY direction in the order of 0--->M1--->M2--->M3--->M4--->M5--->M6--->M7--->M8--->M9--->M10--->M11--->M12--->M13. During the search process, the X-direction grating overlap rate and the Y-direction grating overlap rate need to be recorded after each movement. Based on the X-direction grating overlap rate and the Y-direction grating overlap rate obtained after each movement, the X-alignment coordinates and the Y-alignment coordinates are determined.

[0054] In another preferred embodiment, the X and Y alignment coordinates of the movable stage during each measurement process are determined in the following manner:

[0055] During this measurement process: the X coordinate of the movable stage corresponding to the maximum X-direction grating overlap rate was determined as the X alignment coordinate, and the Y coordinate of the movable stage corresponding to the maximum Y-direction grating overlap rate was determined as the Y alignment coordinate.

[0056] like Figure 4 As shown, among all search positions from 0 to M13, if the position M10 has the maximum X-direction grating overlap rate, then the X coordinate corresponding to the position M10 is determined as the X alignment coordinate. If the position M7 has the maximum Y-direction grating overlap rate, then the Y coordinate corresponding to the position M7 is determined as the Y alignment coordinate. In this application, different alignment positions (X alignment coordinate and Y alignment coordinate) can be obtained under different grating groups.

[0057] In step S300, the grating group position includes the X coordinate of the X-direction grating on the mask stage and the Y coordinate of the Y-direction grating on the mask stage. The horizontal zero position deviation includes the X-direction zero position deviation, Y-direction zero position deviation, and rotation angle zero position deviation of the nominal zero position relative to the actual zero position on the mask stage. The mark position includes the X coordinate of the X-direction alignment mark on the movable worktable and the Y coordinate of the Y-direction alignment mark on the movable worktable. In this application, the grating group position and the mark position are both preset machine constants.

[0058] In one possible implementation, for a single measurement, the following formula exists:

[0059] L·T0·(P-t0)=(Gs)(1)

[0060] In formula (1), T0 represents the zero-position rotation matrix of the mask stage, where, After Taylor expansion, omitting orders higher than 2, we obtain the simplified result. Rz0 is the unknown quantity, representing the zero-position deviation of the rotation angle of the mask stage.

[0061] This indicates the position of the grating group on the mask stage. x p The x-coordinate of the X-direction grating on the mask stage is represented by the y-coordinate. p This represents the Y-coordinate of the Y-direction grating on the mask stage.

[0062] t0 is the unknown quantity, representing the xy component of the zero-position deviation corresponding to the mask stage. Where x0 represents the zero-position deviation in the X direction corresponding to the mask stage, y0 represents the zero-position deviation in the Y direction corresponding to the mask stage, and S represents the stage rotation matrix. R represents the horizontal rotation angle of the worktable. In this application, the movable worktable is not set to rotate, that is, R = 0. At this time, S is the identity matrix.

[0063] G is a machine constant representing the position of the image alignment mark on the reference plate of the worktable on the movable worktable. x g This indicates the X-coordinate of the alignment mark on the movable worktable, and the y-coordinate... g This indicates the Y-coordinate of the alignment mark on the movable worktable in the Y direction.

[0064] L is the machine constant, representing the objective lens magnification, and s is the alignment position of the movable stage obtained during the helical search. x s This represents the X-alignment coordinate determined by measurement, y s This represents the Y-alignment coordinate determined by measurement.

[0065] In a preferred embodiment, formula (1) corresponds to a single measurement, while this application involves multiple measurements. Since L is a machine constant, it is ignored here. Based on the above, formula (1) is transformed, and the formula is fitted by integrating multiple measurements to obtain the following loss function:

[0066]

[0067] In formula (2), F(.) represents the loss function, n represents the total number of measurements, and x pi The x-coordinate of the X-direction grating on the mask stage corresponding to the i-th measurement is y. pi Let Y represent the Y coordinate of the Y-direction grating on the mask stage corresponding to the i-th measurement. siThe x-coordinate corresponds to the i-th measurement, and the y-coordinate corresponds to the y-coordinate. si This represents the Y-alignment coordinate corresponding to the i-th measurement.

[0068] Please see Figure 5 , Figure 5 A flowchart illustrating the steps of a method for determining the zero-point deviation of a target level provided in an embodiment of this application is shown. Figure 5 As shown, step S400 includes:

[0069] (A) Determine the first partial derivative expression of the loss function with respect to the zero deviation in the X direction, the second partial derivative expression with respect to the zero deviation in the Y direction, and the third partial derivative expression with respect to the zero deviation in the rotation angle.

[0070] Specifically, the expression for the first partial derivative is:

[0071]

[0072] The expression for the second partial derivative is:

[0073]

[0074] The expression for the third partial derivative is:

[0075]

[0076] (B) Substitute the current zero deviation in the X direction, the current zero deviation in the Y direction, and the current zero deviation in the rotation angle into the first partial derivative expression, the second partial derivative expression, and the third partial derivative expression, respectively, to obtain the X partial derivative value corresponding to the first partial derivative expression, the Y partial derivative value corresponding to the second partial derivative expression, and the rotation angle partial derivative value corresponding to the third partial derivative expression.

[0077] In this application, when step (B) is executed for the first time, the preset initial values ​​corresponding to x0, y0 and Rz0 are used as the current zero position deviation in the X direction, the current zero position deviation in the Y direction and the current zero position deviation in the rotation angle, so as to complete the update of the zero position deviation in the X direction, the deviation in the Y direction and the zero position deviation in the rotation angle.

[0078] (C) Update the zero position deviation in the X direction, the deviation in the Y direction, and the zero position deviation in the rotation angle based on the calculated X partial derivative, Y partial derivative, and rotation angle partial derivative, respectively.

[0079] In another preferred embodiment, step (C) includes:

[0080] Calculate the first product between the X-direction partial derivative and the mask stage unit step size. The sum of the first product and the current X-direction zero deviation is determined as the updated X-direction zero deviation. Calculate the second product between the Y-direction partial derivative and the mask stage unit step size. The sum of the second product and the current Y-direction zero deviation is determined as the updated Y-direction zero deviation. Calculate the third product between the rotation angle partial derivative and the mask stage unit step size. The sum of the third product and the current rotation angle zero deviation is determined as the updated rotation angle zero deviation.

[0081] (D) Substitute the updated zero-position deviation in the X direction, zero-position deviation in the Y direction, and zero-position deviation in the rotation angle into the loss function to calculate the loss value.

[0082] (E) Compare the loss value with the preset loss threshold, and determine the target level zero deviation based on the comparison result.

[0083] Specifically, the target horizontal zero-position deviation includes the target X-direction zero-position deviation, the target Y-direction zero-position deviation, and the target rotation angle zero-position deviation, wherein step (E) includes:

[0084] If the loss value is greater than or equal to the preset loss threshold, then the updated X-direction deviation, Y-direction deviation and rotation angle deviation are used to return to step (B). If the loss value is less than the preset loss threshold, then the updated X-direction zero deviation, Y-direction zero deviation and rotation angle zero deviation are determined as the target X-direction zero deviation, target Y-direction zero deviation and target rotation angle zero deviation, respectively.

[0085] In this application, the loss function is iteratively calculated based on steps (B) to (E) until the loss value is less than the preset loss threshold, thereby determining the zero position deviation of the target in the X direction, the zero position deviation of the target in the Y direction, and the zero position deviation of the target rotation angle.

[0086] In one example, the nominal zero position includes the nominal zero position X coordinate, the nominal zero position Y coordinate, and the nominal zero position rotation angle.

[0087] The steps for calibrating the horizontal zero position of the mask stage based on the deviation between the nominal zero position and the target horizontal zero position include:

[0088] The difference between the nominal zero-position X coordinate and the target X-direction zero-position deviation is determined as the actual zero-position X coordinate corresponding to the mask stage. The difference between the nominal zero-position Y coordinate and the target Y-direction zero-position deviation is determined as the actual zero-position Y coordinate corresponding to the mask stage. The difference between the nominal zero-position rotation angle and the target rotation angle zero-position deviation is determined as the actual zero-position rotation angle corresponding to the mask stage. The mask stage is then moved to the position indicated by the actual zero-position X coordinate, actual zero-position Y coordinate, and actual zero-position rotation angle to complete the calibration of the horizontal zero position of the mask stage.

[0089] Specifically, the actual zero-position X coordinate can be determined using the following formula:

[0090]

[0091] In formula (3), Indicates the actual zero-position X coordinate. This represents the nominal zero-position X-coordinate.

[0092] The actual zero-position Y-coordinate is determined using the following formula:

[0093]

[0094] In formula (4), Indicates the actual zero-position Y coordinate. This represents the nominal zero-position Y-coordinate.

[0095] The actual zero-position Y-coordinate is determined using the following formula:

[0096]

[0097] In formula (5), Indicates the actual zero-position rotation angle. This indicates the nominal zero-position rotation angle.

[0098] Based on the same application concept, this application also provides a calibration device for the horizontal zero position of the mask stage, which corresponds to the calibration method for the horizontal zero position of the mask stage provided in the above embodiments. Since the principle of the device in this application is similar to the calibration method for the horizontal zero position of the mask stage in the above embodiments of this application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.

[0099] Please see Figure 6 , Figure 6 This diagram illustrates the structure of a calibration device for the horizontal zero position of a mask stage, as provided in an embodiment of this application. Figure 6 As shown, the device includes:

[0100] The projection module 500 is used to turn on the light source. The light emitted by the light source passes through multiple grating groups and objective lenses to form a grating image corresponding to each grating group on the worktable reference plate.

[0101] The measurement module 510 is used to control the movement of the movable stage to perform multiple measurements. During each measurement, the movable stage is controlled to perform a spiral search to align the image alignment mark with a raster image and the corresponding alignment position of the movable stage is recorded.

[0102] The loss function construction module 520 is used to construct a loss function based on the position of the grating group to which the grating image belongs in each measurement on the mask stage, the position of the image alignment mark on the movable worktable, the alignment position of the movable worktable obtained in each measurement, and the horizontal zero deviation of the mask stage.

[0103] Module 530 is determined, and the loss function is iteratively calculated using the gradient descent method to determine the target horizontal zero-position deviation corresponding to the mask stage.

[0104] The calibration module 540 is used to calibrate the horizontal zero position of the mask stage based on the deviation between the nominal zero position and the target horizontal zero position of the mask stage.

[0105] Based on the same application concept, please refer to Figure 7 , Figure 7 The diagram shows a schematic of an electronic device provided in an embodiment of this application. The electronic device 600 includes a processor 610, a memory 620, and a bus 630. The memory 620 stores machine-readable instructions that can be executed by the processor 610. When the electronic device 600 is running, the processor 610 and the memory 620 communicate through the bus 630. When the machine-readable instructions are executed by the processor 610, the steps of the calibration method for the horizontal zero position of the mask stage provided in any of the above embodiments are executed.

[0106] Based on the same concept, this application also provides a computer-readable storage medium storing a computer program, which, when run by a processor, executes the steps of the mask stage horizontal zero-position calibration method provided in the above embodiments.

[0107] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; 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. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection may be through some communication interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0108] 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.

[0109] 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.

[0110] 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 part 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.

[0111] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calibrating the horizontal zero position of a mask stage, applied to a measurement system, the measurement system comprising a light source, a mask stage, an objective lens, and a movable stage, characterized in that, A mask reference plate is fixed on the mask stage, and multiple grating groups are formed on the mask reference plate. A worktable reference plate is fixed on the movable worktable, and image alignment marks are formed on the worktable reference plate. The calibration method includes: When the light source is turned on, the light emitted by the light source passes through the plurality of grating groups and the objective lens to form a grating image corresponding to each grating group on the worktable reference plate; The movable worktable is controlled to move to perform multiple measurements. During each measurement: the movable worktable is controlled to perform a spiral search so that the image alignment mark is aligned with a raster image, and the alignment position of the movable worktable is recorded. Based on the position of the grating group to which the grating image belongs in each measurement on the mask stage, the position of the image alignment mark on the movable worktable, the alignment position of the movable worktable obtained in each measurement, and the horizontal zero deviation of the mask stage, a loss function is constructed. The loss function is iteratively calculated using the gradient descent method to determine the target horizontal zero-position deviation corresponding to the mask stage; The horizontal zero position of the mask stage is calibrated based on the deviation between the nominal zero position of the mask stage and the target horizontal zero position. Each grating group includes an X-direction grating and a Y-direction grating. The image alignment marks include X-direction alignment marks and Y-direction alignment marks. The grating images include X-direction grating images and Y-direction grating images. The alignment positions include X-alignment coordinates and Y-alignment coordinates corresponding to the movable stage. The alignment position of the movable worktable in each measurement process is determined by the following method: During each measurement, the following processing is performed: The movable worktable is controlled to perform a spiral search according to a preset unit step. For each preset unit step, the X-direction grating overlap rate between the X-direction alignment mark and the X-direction alignment mark is obtained, as well as the Y-direction grating overlap rate between the Y-direction alignment mark and the Y-direction alignment mark. Based on the X-direction grating overlap rate and Y-direction grating overlap rate corresponding to each movement of the movable worktable, the X-alignment coordinates and Y-alignment coordinates corresponding to each measurement are determined.

2. The calibration method according to claim 1, characterized in that, The X and Y alignment coordinates of the movable stage during each measurement process are determined using the following method: During each measurement: The X coordinate of the movable worktable corresponding to the maximum X-direction grating overlap rate is determined as the X alignment coordinate. The Y coordinate of the movable worktable corresponding to the maximum Y-direction grating overlap rate is determined as the Y alignment coordinate.

3. The calibration method according to claim 1, characterized in that, The grating group position includes the X coordinate of the X-direction grating on the mask stage and the Y coordinate of the Y-direction grating on the mask stage. The horizontal zero-position deviation includes the X-direction zero-position deviation, Y-direction zero-position deviation, and rotation angle zero-position deviation of the nominal zero position corresponding to the mask stage relative to the actual zero position. The mark position includes the X coordinate of the X-direction alignment mark on the movable worktable and the Y coordinate of the Y-direction alignment mark on the movable worktable. The loss function is constructed using the following formula: In the formula, Represents the loss function. Indicates the total number of measurements. This is the zero-position deviation of the rotation angle. Indicates the first The X coordinate of the X-direction grating on the mask stage corresponding to this measurement. Indicates the first The Y coordinate of the Y-direction grating on the mask stage corresponding to this measurement; This represents the zero-position deviation in the X direction. The zero-position deviation is in the Y direction. This indicates the X-coordinate of the alignment mark on the movable worktable in the X direction. This indicates the Y-coordinate of the alignment mark on the movable worktable. Indicates the first The X alignment coordinates corresponding to this measurement. Indicates the first The Y-alignment coordinates corresponding to this measurement.

4. The calibration method according to claim 3, characterized in that, The steps for iteratively calculating the loss function using the gradient descent method to determine the target horizontal zero-position deviation corresponding to the mask stage include: (A) Determine the first partial derivative expression of the loss function with respect to the zero deviation in the X direction, the second partial derivative expression with respect to the zero deviation in the Y direction, and the third partial derivative expression with respect to the zero deviation in the rotation angle; (B) Substitute the current zero position deviation in the X direction, the current zero position deviation in the Y direction, and the current zero position deviation in the rotation angle into the first partial derivative expression, the second partial derivative expression, and the third partial derivative expression, respectively, to obtain the X-direction partial derivative value corresponding to the first partial derivative expression, the Y-direction partial derivative value corresponding to the second partial derivative expression, and the rotation angle partial derivative value corresponding to the third partial derivative expression. (C) Update the zero position deviation in the X direction, the zero position deviation in the Y direction, and the zero position deviation in the rotation angle based on the calculated partial derivative values ​​in the X direction, Y direction, and rotation angle, respectively; (D) Substitute the updated zero-position deviation in the X direction, zero-position deviation in the Y direction, and zero-position deviation in the rotation angle into the loss function to calculate the loss value; (E) Compare the loss value with a preset loss threshold, and determine the target level zero deviation based on the comparison result.

5. The calibration method according to claim 4, characterized in that, Step (C) includes: Calculate the first product between the X-direction partial derivative value and the mask stage unit step size, and determine the sum of the first product and the current X-direction zero deviation as the updated X-direction zero deviation; Calculate the second product between the Y-direction partial derivative value and the mask stage unit step size, and determine the sum of the second product and the current Y-direction zero deviation as the updated Y-direction zero deviation; Calculate the third product between the partial derivative of the rotation angle and the unit step of the mask stage, and determine the sum of the third product and the current zero deviation of the rotation angle as the updated zero deviation of the rotation angle.

6. The calibration method according to claim 5, characterized in that, The target horizontal zero-position deviation includes the target X-direction zero-position deviation, the target Y-direction zero-position deviation, and the target rotation angle zero-position deviation. Step (E) includes: If the loss value is greater than or equal to the preset loss threshold, then the updated X-direction zero deviation, Y-direction zero deviation and rotation angle zero deviation are used to return to step (B). If the loss value is less than the preset loss threshold, the updated zero-position deviation in the X direction, the zero-position deviation in the Y direction, and the zero-position deviation in the rotation angle are respectively determined as the target zero-position deviation in the X direction, the target zero-position deviation in the Y direction, and the target zero-position deviation in the rotation angle.

7. The calibration method according to claim 6, characterized in that, The nominal zero position includes the nominal zero position X coordinate, the nominal zero position Y coordinate, and the nominal zero position rotation angle. The step of calibrating the horizontal zero position of the mask stage based on the deviation between the nominal zero position and the target horizontal zero position includes: The difference between the nominal zero-position X coordinate and the target X-direction zero-position deviation is determined as the actual zero-position X coordinate corresponding to the mask stage; The difference between the nominal zero-position Y coordinate and the target Y-direction zero-position deviation is determined as the actual zero-position Y coordinate corresponding to the mask stage; The difference between the nominal zero-position rotation angle and the target rotation angle zero-position deviation is determined as the actual zero-position rotation angle corresponding to the mask stage; The mask stage is controlled to move to the position indicated by the actual zero position X coordinate, the actual zero position Y coordinate, and the actual zero position rotation angle, so as to complete the calibration of the horizontal zero position of the mask stage.

8. A calibration device for the horizontal zero position of a mask stage, applied to a measurement system, the measurement system comprising a light source, a mask stage, an objective lens, and a movable stage, characterized in that, A mask reference plate is fixed on the mask stage, and multiple grating groups are formed on the mask reference plate. A worktable reference plate is fixed on the movable worktable, and image alignment marks are formed on the worktable reference plate. The calibration device employs the calibration method as described in any one of claims 1-7, comprising: A projection module is used to turn on the light source, and the light emitted by the light source passes through the multiple grating groups and the objective lens to form a grating image corresponding to each grating group on the worktable reference plate; The measurement module is used to control the movement of the movable worktable to perform multiple measurements. During each measurement, the movable worktable is controlled to perform a spiral search so that the image alignment mark is aligned with a raster image, and the alignment position of the movable worktable is recorded. The loss function construction module is used to construct a loss function based on the position of the grating group to which the grating image belongs in each measurement on the mask stage, the position of the image alignment mark on the movable worktable, the alignment position of the movable worktable obtained in each measurement, and the horizontal zero deviation of the mask stage. The module is determined by iteratively calculating the loss function using the gradient descent method to determine the target horizontal zero-position deviation corresponding to the mask stage. The calibration module is used to calibrate the horizontal zero position of the mask stage based on the deviation between the nominal zero position of the mask stage and the target horizontal zero position.

9. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. The machine-readable instructions are executed by the processor to perform the steps of the mask stage horizontal zero-position calibration method as described in any one of claims 1 to 7.

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