Mark positioning method and system based on object space telecentric lens

Abstract

The invention provides a mark positioning method and system based on an object space telecentric lens, and the method comprises the steps: determining a mechanical pixel x-axis multiplying power, a mechanical pixel y-axis multiplying power, x-axis telecentricity and y-axis telecentricity corresponding to image collection equipment based on the object space telecentric lens, determining a target transformation matrix from a pixel coordinate system to a mechanical coordinate system according to the mechanical pixel x-axis multiplying power, the mechanical pixel y-axis multiplying power, the mechanical x-axis coordinate, the mechanical y-axis coordinate and the mechanical z-axis coordinate of the equipment center point, the focal length of the image acquisition equipment, the x-axis telecentricity and the y-axis telecentricity; and obtaining the position marked by the reference mark plate, the position marked by the mask and the target conversion matrix of the pixel coordinate system and the mechanical coordinate system, determining the moving path of the mask workbench, and controlling the mask workbench to move. According to the method, marking positioning is carried out through effective fusion of parameters such as telecentricity and mechanical pixel multiplying power, and three-dimensional space accurate positioning of the target object with higher precision can be realized.

Description

Technical Field

[0001] The present application relates to the field of photolithography positioning technology, and in particular to a marking positioning method and system based on an object-side telecentric lens. Background Art

[0002] The photolithography process is a key step in the manufacturing process of semiconductor integrated circuits. Specifically, the pattern designed on the mask is transferred to the reference mark plate for fine processing by using processes such as exposure. In the process of making semiconductor reference mark plates, it is necessary to control the workbench where the mask is located to move to a certain position so that the mask mark and the semiconductor reference mark plate mark are aligned, thereby improving the overlay accuracy.

[0003] In the prior art, a simple measuring camera is used to collect images of mask marks and semiconductor fiducial mark plate marks, and a video image processing alignment technology (field image alignment, FIA) is used to process the positioning of the camera imaging to the real three-dimensional space according to the x-axis magnification, y-axis magnification and the coordinates of the center point of the camera field of view.

[0004] However, the prior art does not effectively integrate the telecentricity of the measuring camera and the camera internal parameters during the alignment process, and ignores the mutual influence between the data, resulting in the inability to accurately locate the target object in three-dimensional space. Summary of the invention

[0005] The purpose of the present application is to provide a marker positioning method and system based on an object-side telecentric lens to address the deficiencies in the above-mentioned prior art, so as to solve the problem in the prior art that it is impossible to accurately position the target object in three-dimensional space.

[0006] To achieve the above objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a marker positioning method based on an object-side telecentric lens, the method comprising:

[0008] Determine the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity, and y-axis telecentricity corresponding to the image acquisition device based on the object-space telecentric lens;

[0009] Determine a target transformation matrix from a pixel coordinate system to a mechanical coordinate system according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, a preset device center point mechanical x-axis coordinate, a preset device center point mechanical y-axis coordinate, a preset device center point mechanical z-axis coordinate, a preset image acquisition device focal length, the x-axis telecentricity, and the y-axis telecentricity;

[0010] Acquire the position of the reference mark plate mark and the position of the mask mark in the image of the measured object sent by the image acquisition device;

[0011] Determining a movement path of the mask stage according to the position of the reference mark plate mark, the position of the mask mark, and a target transformation matrix between the pixel coordinate system and the mechanical coordinate system;

[0012] The mask stage is controlled to move according to the mask stage movement path so that the mask mark in the mask set on the mask stage is aligned with the reference mark plate mark in the reference mark plate.

[0013] Optionally, determining a target transformation matrix from a pixel coordinate system to a mechanical coordinate system according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, a preset device center point mechanical x-axis coordinate, a preset device center point mechanical y-axis coordinate, a preset device center point mechanical z-axis coordinate, a preset image acquisition device focal length, an x-axis telecentricity, and a y-axis telecentricity includes:

[0014] Establish pixel coordinate system, image coordinate system, camera coordinate system and mechanical coordinate system;

[0015] Establishing a first transformation matrix from the image coordinate system to the pixel coordinate system;

[0016] Establishing a second transformation matrix from the camera coordinate system to the image coordinate system;

[0017] Establishing a third transformation matrix between the mechanical coordinate system and the camera coordinate system;

[0018] Determine a conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix;

[0019] The mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity are input into the transformation matrix between the pixel coordinate system and the mechanical coordinate system to obtain a target transformation matrix from the pixel coordinate system to the mechanical coordinate system.

[0020] Optionally, the establishing of a first transformation matrix from the image coordinate system to the pixel coordinate system includes:

[0021] The position coordinates of the origin of the image coordinate system in the pixel coordinate system are set to preset values, and a first conversion matrix from the image coordinate system to the pixel coordinate system is obtained.

[0022] Optionally, determining a conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix includes:

[0023] Determine a first inverse transformation matrix corresponding to the first transformation matrix;

[0024] Determine a second inverse transformation matrix corresponding to the second transformation matrix;

[0025] A conversion matrix between the pixel coordinate system and the mechanical coordinate system is determined according to the first inverse conversion matrix, the second inverse conversion matrix and the third conversion matrix.

[0026] Optionally, determining the conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first inverse conversion matrix, the second inverse conversion matrix and the third conversion matrix includes:

[0027] Multiplying the third conversion matrix, the second inverse conversion matrix and the first conversion matrix to obtain a conversion matrix between the pixel coordinate system and the mechanical coordinate system;

[0028] Among them, the transformation matrix between the pixel coordinate system and the mechanical coordinate system is:

[0029]

[0030] in, is the third transformation matrix, is the second transformation inverse matrix, is the first inverse transformation matrix, α is the x-axis telecentricity, β is the y-axis telecentricity, t x is the mechanical x-axis coordinate of the center point of the device, t y is the mechanical y-axis coordinate of the center point of the device, z M is the mechanical z-axis coordinate of the center point of the device, m is the ratio of the focal length of the image acquisition device to the mechanical z-axis coordinate of the center point of the device, dx is the mechanical pixel x-axis magnification, and dy is the mechanical pixel y-axis magnification.

[0031] Optionally, determining the movement path of the mask stage according to the position of the reference mark plate mark, the position of the mask mark and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system comprises:

[0032] Determine a moving start position according to the position of the mask mark in the image of the measured object and a target transformation matrix between the pixel coordinate system and the mechanical coordinate system;

[0033] Determining the end position of movement according to the position of the reference mark plate mark in the image of the measured object and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system;

[0034] The moving path of the mask working table is determined according to the moving starting position and the moving ending position.

[0035] Optionally, determining the moving start position according to the position of the mask mark in the image of the measured object and a target transformation matrix between the pixel coordinate system and the mechanical coordinate system includes:

[0036] The moving start position is obtained by multiplying the vector corresponding to the position of the mask mark with the target transformation matrix between the pixel coordinate system and the mechanical coordinate system.

[0037] Optionally, the method further comprises:

[0038] Determine a conversion matrix from a mechanical coordinate system to a pixel coordinate system according to the first conversion matrix, the second conversion matrix, and the third conversion matrix;

[0039] The mark position in the pixel coordinate system is determined according to the conversion matrix from the mechanical coordinate system to the pixel coordinate system, the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity, and the mark position in the mechanical coordinate system.

[0040] Optionally, determining a conversion matrix from a mechanical coordinate system to a pixel coordinate system according to the first conversion matrix, the second conversion matrix, and the third conversion matrix includes:

[0041] Multiplying the first conversion matrix, the second conversion matrix and the third conversion matrix to obtain a conversion matrix from a mechanical coordinate system to a pixel coordinate system;

[0042] The conversion matrix from the mechanical coordinate system to the pixel coordinate system is:

[0043]

[0044] in, is the first transformation matrix, is the second transformation matrix, is the third conversion matrix, dx is the mechanical pixel x-axis magnification, dy is the mechanical pixel y-axis magnification, f is the focal length of the image acquisition device, α is the x-axis telecentricity, β is the y-axis telecentricity, t x is the mechanical x-axis coordinate of the center point of the device, t y It is the mechanical y-axis coordinate of the center point of the device.

[0045] In the second aspect, the present application provides a marking positioning system based on an object-side telecentric lens, the marking positioning system based on the object-side telecentric lens comprising a control module, an image acquisition device, a mask workbench and a reduced projection lens, the image acquisition device being used to sequentially acquire an image of a measured object through the reduced projection lens and the object-side telecentric lens, the image of the measured object comprising a mask mark of the mask on the mask workbench and a reference mark plate mark in a reference mark plate, and the image of the measured object is sent to the control module, the control module being used to execute the steps of the marking positioning method based on the object-side telecentric lens as described in the first aspect.

[0046] The beneficial effects of the present application are as follows: first, the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity and y-axis telecentricity corresponding to the image acquisition device based on the object-side telecentric lens are determined. Since the image acquisition device uses an object-side telecentric lens, the measured x-axis telecentricity and y-axis telecentricity have very small deviations from the actual optical path and the telecentricity of the mask stage, thereby improving the three-dimensional spatial positioning of the target object. Then, the target conversion matrix from the pixel coordinate system to the mechanical coordinate system is determined according to the above-mentioned mechanical pixel magnification, telecentricity, preset device center point coordinates and preset image acquisition device focal length. Next, the position of the reference mark plate mark and the position of the mask mark sent by the image acquisition device are obtained, and the mask workbench movement path is determined according to the target conversion matrix of the pixel coordinate system and the mechanical coordinate system, thereby controlling the movement of the mask workbench. In the above method, the mark positioning is performed by effectively integrating the telecentricity collected by the image acquisition device and the camera parameters such as the mechanical pixel x-axis magnification and the mechanical pixel y-axis magnification, so that the three-dimensional spatial precise positioning of the target object with higher precision can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 It is a schematic diagram of an application scenario of a marking positioning method based on an object-side telecentric lens provided in an embodiment of the present application;

[0049] Figure 2 It is a flow chart of a marking positioning method based on an object-side telecentric lens provided in an embodiment of the present application;

[0050] Figure 3 It is a schematic diagram of a telecentricity measurement principle provided by an embodiment of the present application;

[0051] Figure 4 It is a schematic diagram of a reference mark plate mark and a mask mark provided in an embodiment of the present application;

[0052] Figure 5 is a flowchart of the steps of determining a target transformation matrix from a pixel coordinate system to a mechanical coordinate system provided by an embodiment of the present application;

[0053] Figure 6 It is a schematic diagram of the imaging principle of an image acquisition device provided in an embodiment of the present application;

[0054] Figure 7 is a schematic diagram of the relationship between a camera coordinate system and an image coordinate system provided in an embodiment of the present application;

[0055] Figure 8 is a schematic diagram of the relationship between an image coordinate system and a pixel coordinate system provided in an embodiment of the present application;

[0056] Fig. 9 It is a schematic flow chart of a method for determining a conversion matrix between a pixel coordinate system and a mechanical coordinate system provided in an embodiment of the present application;

[0057] Fig.10 It is a flow chart of a method for determining a moving path of a mask workbench provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0059] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0060] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0061] In the prior art, the FIA ​​method is used to perform target positioning based on images. Specifically, the camera imaging is processed into the real three-dimensional space by measuring the camera's x-axis magnification, y-axis magnification and the coordinates of the camera's field of view center point. However, the prior art does not effectively integrate the telecentricity of the measured camera and the camera's internal parameters during the alignment process, ignoring the mutual influence between the data, resulting in the inability to accurately position the target object in three-dimensional space.

[0062] Based on this, the present application proposes a marking positioning method based on an object-side telecentric lens, which is applied in a control module of a marking positioning system. The method first determines the mechanical pixel magnification and telecentricity corresponding to the image acquisition device based on the object-side telecentric lens, and determines the target conversion matrix from the pixel coordinate system to the mechanical coordinate system according to the mechanical coordinates of the center point of the device. The target conversion matrix from the pixel coordinate system to the mechanical coordinate system is used to determine the movement of the mask workbench in the mechanical coordinates based on the pixel length of the image of the object to be measured acquired by the image acquisition device. During use, the position of the reference mark plate mark and the position of the mask mark in the image of the object to be measured sent by the image acquisition device are first obtained, wherein the position of the reference mark plate mark and the position of the mask mark are both coordinates in the pixel coordinate system, and then the moving distance of the mask workbench is determined according to the target conversion matrix from the pixel coordinate system to the mechanical coordinate system, and the movement of the mask workbench is controlled according to the moving path of the mask workbench, and the moving path is the path in the mechanical coordinate system. In the present application, not only the mechanical pixel magnification, telecentricity and mechanical coordinates of the device center point are used in the process of converting the pixel coordinate system to the mechanical coordinate system to achieve accurate three-dimensional spatial positioning, but also the object-side telecentric lens is used to overcome the imaging characteristics of large objects near and small objects far away, so that the accuracy of target space positioning is improved when the reference mark plate mark and the mask mark are aligned.

[0063] Before introducing the specific implementation steps of the marker positioning method based on the object-space telecentric lens, the application scenarios of the method are first introduced. Figure 1 Schematic diagram of an application scenario of a marker positioning method based on an object-side telecentric lens provided in an embodiment of the present application. Figure 1As shown, the mark positioning method based on the object telecentric lens is applied in the mark positioning system based on the object telecentric lens, the system includes a control module, an image acquisition device, a mask workbench and a reduced projection lens, wherein the image acquisition device has an object telecentric lens, the image acquisition device is used to sequentially obtain the image of the object to be measured through the reduced projection lens and the object telecentric lens, and send the image of the object to the control module, the control module is used to receive the image of the object to be measured sent by the image acquisition device, and control the movement of the mask workbench according to the position of the reference mark plate mark and the position of the mask mark in the image of the object to be measured. Among them, one or more reference mark plates are set corresponding to a silicon wafer, and the mask mark on the mask workbench is aligned with the reference mark plate, so that the silicon wafer is photolithographically processed through the mask. As an optional embodiment, since there may be two or more reference mark plate marks in a reference mark plate, specifically, including coarse alignment marks and fine alignment marks, multiple image acquisition devices with object telecentric lenses can be set to align each reference mark plate mark and mask mark.

[0064] Next, refer to Figure 2 The specific implementation process of the marker positioning method based on the object-space telecentric lens is introduced. Figure 2 It is a flow chart of a marking positioning method based on an object-side telecentric lens provided in an embodiment of the present application.

[0065] S201, determining a mechanical pixel x-axis magnification, a mechanical pixel y-axis magnification, an x-axis telecentricity, and a y-axis telecentricity corresponding to an image acquisition device based on an object-side telecentric lens.

[0066] Among them, the mechanical pixel x-axis magnification corresponding to the image acquisition device based on the object space telecentric lens is the ratio of the unit pixel length of the x-axis of the image acquisition device to the mechanical moving length of the mask workbench. The mechanical pixel y-axis magnification is the ratio of the unit pixel length of the y-axis of the image acquisition device to the mechanical moving length of the mask workbench. The x-axis telecentricity is the rotational offset angle of the optical path relative to the mask workbench in the x-axis direction, and the y-axis telecentricity is the rotational offset angle of the optical path relative to the mask workbench in the y-axis direction.

[0067] As an optional implementation, the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity, and y-axis telecentricity corresponding to the image acquisition device can be determined through a pre-adjustment process. The pre-adjustment process is to control the mask workbench to translate the x-axis and y-axis, and rotate the x-axis and y-axis, so as to determine the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity, and y-axis telecentricity according to the moving pixel distance and the mechanical moving distance.

[0068] As an optional implementation, a method for obtaining the mechanical pixel x-axis magnification and mechanical pixel y-axis magnification corresponding to the object telecentric lens is as follows: control the mask stage to move horizontally based on a unit moving step according to a preset mechanical distance and a preset mechanical direction, and control the object telecentric lens to collect the image of the object to be measured during the movement of the mask stage, wherein the mask stage is located in the field of view of the object telecentric lens. The quotient of the pixel distance of the object to be measured along the x-axis in the image of the object to be measured and the mechanical distance of the mask stage along the x-axis is used as the mechanical pixel x-axis magnification, and the quotient of the pixel distance of the object to be measured along the y-axis in the image of the object to be measured and the mechanical distance of the mask stage along the y-axis is used as the mechanical pixel y-axis magnification. Wherein, the object to be measured can be a mask mark. Optionally, the steps of controlling the mask stage to move horizontally according to a preset mechanical distance and a preset mechanical direction, and controlling the object telecentric lens to collect the image of the object to be measured during the movement of the mask stage can be performed multiple times to obtain multiple x-axis magnifications and y-axis magnifications to be selected. After removing outliers by the three sigma method, the average of the removed candidate x-axis magnifications and the candidate y-axis magnifications is calculated to obtain the mechanical pixel x-axis magnification and the mechanical pixel y-axis magnification, so that the mechanical pixel x-axis magnification and the mechanical pixel y-axis magnification are more accurate.

[0069] As an optional implementation, the method for obtaining the x-axis telecentricity and y-axis telecentricity corresponding to the object-side telecentric lens is as follows: control the mask stage to move vertically according to the preset mechanical distance and the direction close to the mask stage, and control the object-side telecentric lens to collect the image of the object to be measured during the movement of the mask stage, wherein the mask stage is located in the field of view of the object-side telecentric lens. The ratio of the mechanical distance corresponding to the pixel distance of the x-axis moved by the object to be measured in the image of the object to be measured to the preset mechanical distance is used as the tangent value of the x-axis telecentricity, and the ratio of the mechanical distance corresponding to the pixel distance of the y-axis moved by the object to be measured in the image of the object to be measured to the preset mechanical distance is used as the tangent value of the y-axis telecentricity. The mechanical distance corresponding to the pixel distance can be calculated and determined according to the mechanical pixel x-axis magnification and the mechanical pixel y-axis magnification.

[0070] For example, Figure 3 Schematic diagram of telecentricity measurement principle provided by an embodiment of the present application. Figure 3 As shown, the center position of the measured object image changes when the mask workbench moves vertically, and the ratio of the preset mechanical distance to the mechanical distance corresponding to the pixel distance moved by the measured object in the measured object image can be used as the telecentricity.

[0071] S202. Determine a target transformation matrix from the pixel coordinate system to the mechanical coordinate system according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity, and the y-axis telecentricity.

[0072] The pixel coordinate system is used to represent the projection coordinates of the measured object on the discrete image plane. The coordinate axes of the pixel coordinate system can be represented by (u, v), and its unit scale is one pixel. The mechanical coordinate system is a reference system used to represent the position of the measured object. Its coordinate axes are (x mcs ,y mcs , z mcs ), in this embodiment, the origin of the mechanical coordinate system can be set directly below the reduced projection lens, where x mcs Axis and y mcs The axis direction is determined by the installation of the servo, and the specific position in the mechanical coordinate system can be determined by reading the high-precision interferometer.

[0073] Optionally, the target transformation matrix from the pixel coordinate system to the mechanical coordinate system is specifically used to transform the coordinates in the pixel coordinate system into the coordinates in the mechanical coordinate system. Further, the target transformation matrix can transform the moving path in the pixel coordinate system into the moving path in the mechanical coordinate system, so that the mask stage can move according to the moving path in the mechanical coordinate system transformed from the moving path in the pixel coordinate system.

[0074] As an optional implementation, the target conversion matrix from the pixel coordinate system to the mechanical coordinate system can be determined according to the conversion matrix from the pixel coordinate system to the mechanical coordinate system and according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset mechanical x-axis coordinate of the center point of the device, the preset mechanical y-axis coordinate of the center point of the device, the preset mechanical z-axis coordinate of the center point of the device, the preset focal length of the image acquisition device, the x-axis telecentricity and the y-axis telecentricity. Among them, the mechanical x-axis coordinate of the center point of the device and the mechanical y-axis coordinate of the center point of the device are both the coordinates of the image acquisition device in the mechanical coordinate system, and the mechanical z-axis coordinate of the center point of the device is pre-set according to the position of the measured object. Specifically, the z-axis coordinate of the device is adjusted, and when the device image is clear, the coordinate of the center point of the device on the mechanical z-axis is the mechanical z-axis coordinate of the center point of the device. In the marking positioning process of the reference marking plate, the mechanical x-axis coordinate of the center point of the device, the mechanical y-axis coordinate of the center point of the device and the mechanical z-axis coordinate of the center point of the device are all pre-set and do not change during the marking positioning process. The focal length of the image acquisition device is determined by the model of the image acquisition device.

[0075] As another optional implementation, the target transformation matrix from the mechanical coordinate system to the pixel coordinate system can be determined based on the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity, thereby determining the moving path in the pixel coordinate system corresponding to the moving path in the mechanical coordinate system based on the target transformation matrix from the mechanical coordinate system to the pixel coordinate system.

[0076] It is worth noting that, since the image acquisition device uses an object-space telecentric lens, the x-axis telecentricity and y-axis telecentricity have very small deviations from the actual optical path and the telecentricity of the mask stage. Therefore, the conversion relationship from the pixel coordinate system to the mechanical coordinate system determined according to the determined x-axis telecentricity and y-axis telecentricity is more accurate, so that the movement of the mask stage is more precise.

[0077] S203, obtaining the position of the reference mark plate mark and the position of the mask mark in the image of the measured object sent by the image acquisition device.

[0078] Among them, in the image of the object under test captured by the image acquisition device, the mark of the reference mark plate is projected onto the photosensitive original of the device through the reduction projection lens and the object side telecentric lens in sequence, and the mask mark is directly projected onto the photosensitive original of the image acquisition device through the object side telecentric lens.

[0079] It is worth noting that the positions of the reference mark plate marks and the mask marks in the image of the object being measured sent by the image acquisition device are both positions in the pixel coordinate system.

[0080] S204, determining the movement path of the mask workbench according to the position of the reference mark plate mark, the position of the mask mark, and the target conversion matrix between the pixel coordinate system and the mechanical coordinate system.

[0081] Specifically, since the position of the reference mark plate mark and the position of the mask mark are both positions in the pixel coordinate system, the position of the reference mark plate mark and the position of the mask mark in the mechanical coordinate system can be determined based on the target transformation matrix between the pixel coordinate system and the mechanical coordinate system, thereby determining the movement path of the mask workbench based on the position of the reference mark plate mark and the position of the mask mark.

[0082] S205 , controlling the mask workbench to move according to the mask workbench moving path so that the mask mark in the mask set on the mask workbench is aligned with the reference mark plate mark in the reference mark plate.

[0083] The mask stage may include a mask carrier and a mask, the mask includes a mask mark corresponding to a mark on a fiducial mark plate, and the fiducial mark plate is located on the wafer carrier. After determining the movement path of the mask stage, the control module controls the mask carrier to move so that the mask mark of the mask on the mask stage is aligned with the fiducial mark plate mark in the fiducial mark plate. After aligning the fiducial mark plate mark with the mask mark, the silicon wafer on the wafer carrier may be overlaid according to the path mode and path expansion percentage preset by the user.

[0084] As an optional implementation, Figure 4 Schematic diagram of a reference mark plate mark and a mask mark provided in an embodiment of the present application. Figure 4 As shown, the reference mark plate mark includes: a first reference mark plate mark and a second reference mark plate mark.

[0085] The first reference mark plate is marked as a square hollow ring with an outer width of 70 microns and an inner width of 50 microns. The second reference mark plate includes a left part, a middle part and a right part, the left part and the middle part are separated by 7 microns, and the middle part and the right part are separated by 7 microns, wherein the left part includes three vertical lines with a width of 7 microns, a spacing of 7 microns, and a length of 80 microns, the right part includes three vertical lines with a width of 7 microns, a spacing of 7 microns, and a length of 80 microns, the middle part includes a horizontal line with a width of 7 microns, a spacing of 7 microns, and a length of 80 microns, and the left part, the middle part and the right part are flush with each other. The mask mark includes an upper part, a lower part, a left part and a right part, wherein the upper part includes two horizontal lines with a width of 20 microns and a spacing of 20 microns, the lower part includes two horizontal lines with a width of 20 microns and a spacing of 20 microns, the left part includes two vertical lines with a width of 20 microns and a spacing of 20 microns, the right part includes two horizontal lines with a width of 20 microns and a spacing of 20 microns, the bottom edge of the upper part is 5 microns away from the left part and the right part, and the left part and the right part are 5 microns away from the lower part. By using the above-mentioned reference mark plate mark and mask mark, the calculation accuracy can be improved.

[0086] Among them, the first reference mark plate mark, the second reference mark plate mark and the mask mark can be used for x-axis magnification and y-axis magnification measurement, and the second reference mark plate mark and the mask mark can be used for x-axis telecentricity and y-axis telecentricity measurement.

[0087] In this embodiment, the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity and y-axis telecentricity corresponding to the image acquisition device based on the object telecentric lens are first determined. Since the image acquisition device uses an object telecentric lens, the measured x-axis telecentricity and y-axis telecentricity have very small deviations from the actual optical path and the telecentricity of the mask stage, thereby improving the three-dimensional spatial positioning of the target object. Then, the target conversion matrix from the pixel coordinate system to the mechanical coordinate system is determined according to the above-mentioned mechanical pixel magnification, telecentricity, preset device center point coordinates and preset image acquisition device focal length. Next, the position of the reference mark plate mark and the position of the mask mark sent by the image acquisition device are obtained, and the mask workbench movement path is determined according to the target conversion matrix of the pixel coordinate system and the mechanical coordinate system, thereby controlling the movement of the mask workbench. In the above method, the mark positioning is performed by effectively integrating the telecentricity collected by the image acquisition device and the camera parameters such as the mechanical pixel x-axis magnification and the mechanical pixel y-axis magnification, so that the three-dimensional spatial precise positioning of the target object with higher accuracy can be achieved.

[0088] Next, refer to Figure 5 Explain the determination of the target transformation matrix from the pixel coordinate system to the mechanical coordinate system in the above step S202 according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity. Wherein, Figure 5 It is a flowchart of the steps of determining a target transformation matrix from a pixel coordinate system to a mechanical coordinate system provided by an embodiment of the present application.

[0089] S501 , establishing a pixel coordinate system, an image coordinate system, a camera coordinate system and a mechanical coordinate system.

[0090] The image coordinate system is a coordinate system established with the intersection of the diagonal lines of the image as the reference origin. Its unit is meter or millimeter. The coordinate axis of the image coordinate system is (x p ,y p The camera coordinate system is the coordinate system of the image acquisition device itself, and its coordinate axis is (x M ,y M , z M ). Figure 6 is a schematic diagram of the imaging principle of an image acquisition device provided in an embodiment of the present application, Figure 7 Schematic diagram of the relationship between a camera coordinate system and an image coordinate system provided in an embodiment of the present application. Figure 6 and Figure 7As shown in the figure, the lens in the image acquisition device is equivalent to a convex lens, and the photosensitive element forms an image opposite to the actual object being measured at the focus of the convex lens. In actual shooting, when the object distance is much greater than 2 times the focal length of the image acquisition device, the image acquisition device forms an image such as Figure 6 As shown in , it is similar to pinhole imaging at the focal length. The pinhole surface in the imaging structure is located between the imaging plane and the object point plane where the object to be measured is located. Figure 7 As shown, the camera coordinate system is established at the origin of the pinhole surface, and the image coordinate system is established on the object point plane side of the pinhole surface. The origin distance between the image coordinate system and the camera coordinate system is the focal length of the image acquisition device. M Axis and image coordinate system x p The axis direction is the same, the y M Axis and y in image coordinate system p The axis direction is the same, the z of the camera coordinate system M The axis is the direction from the origin to the origin of the image coordinate system.

[0091] exist Figure 7 In the camera coordinate system, assume that there is a point M(x M ,y M , z M ), then there exists a point P(x p ,y p ), the following formula (1) can be obtained by the similarity principle:

[0092]

[0093] Among them, f p This is the focal length f of the image acquisition device.

[0094] S502: Establish a first transformation matrix from the image coordinate system to the pixel coordinate system.

[0095] Optionally, Figure 8 Schematic diagram of the relationship between an image coordinate system and a pixel coordinate system provided in an embodiment of the present application. Figure 8 As shown in the figure, the origin of the pixel coordinate system is located at the lower left of the origin of the image coordinate system, and the pixel coordinate system and the image coordinate system have a translation relationship. (u0, v0) represents the coordinates of the origin of the image coordinate system in the pixel coordinate system. Specifically, the u axis of the pixel coordinate system represents the column where the pixel is located, and the v axis represents the row where the pixel is located. The u axis of the pixel coordinate system is the same as the x axis of the image coordinate system. p The axes are parallel and in the same direction, the v axis of the pixel coordinate system and the y axis of the image coordinate system p The axes are parallel and in the same direction.

[0096] Optionally, the transformation relationship from the image coordinate system to the pixel coordinate system may be as follows (2):

[0097]

[0098] Where dx is the x coordinate of a single pixel in the image coordinate system. p The physical length of the axis. dy is the y coordinate of a single pixel in the image coordinate system. p The physical length along the axis.

[0099] As an optional implementation, the specific process of establishing the first transformation matrix from the image coordinate system to the pixel coordinate system in step S502 includes the following steps.

[0100] Optionally, the position coordinates of the origin of the image coordinate system in the pixel coordinate system are set to preset values ​​to obtain a first conversion matrix from the image coordinate system to the pixel coordinate system.

[0101] Among them, the preset value can be (0, 0).

[0102] Specifically, the origin of the pixel coordinate system is set to the center of the image, that is, the geometric center of the pixel arrangement, so (u0, v0) can be set to a preset value. Optionally, (u0, v0) is set to (0, 0), so the conversion relationship from the image coordinate system to the pixel coordinate system can be the following equation (3):

[0103]

[0104] in, This is the first transformation matrix.

[0105] This embodiment achieves higher-speed calculation and simplifies the amount of calculation parameters by setting the position coordinates of the origin of the image coordinate system in the pixel coordinate system to a preset value.

[0106] S503: Establish a second transformation matrix from the camera coordinate system to the image coordinate system.

[0107] Optionally, based on the relationship between the camera coordinate system and the image coordinate system, as shown in equation (1), a transformation relationship from the camera coordinate system to the image coordinate system can be obtained, as shown in equation (4):

[0108]

[0109] Among them, (x p ,y p , 1) is the homogeneous coordinate of the point in the image coordinate system, (x M ,y M , z M , 1) is the homogeneous coordinate of the point in the camera coordinate system.

[0110] To simplify the conversion relationship, based on the normalization principle, let z Mis 1, then according to the above formula (3), we can get formula (5):

[0111]

[0112] in, This is the second transformation matrix.

[0113] S504: Establish a third conversion matrix between the mechanical coordinate system and the camera coordinate system.

[0114] In actual business, the camera coordinate system and the mechanical coordinate system are both three-dimensional coordinates, so the mechanical coordinate system and the camera coordinate system can be translated and rotated to perform mutual conversion. For example, the conversion relationship between the mechanical coordinate system and the camera coordinate system can be shown as formula (6):

[0115]

[0116] in, That is the third transformation matrix, R represents the rotation matrix, and T represents the translation matrix.

[0117] For example, R can be Where α is the x-axis telecentricity, β is the y-axis telecentricity, and T can be Indicates that in x mcs Axis, y mcs Axis and z mcs The distance of the on-axis translation. Since the distance change between the lens and the measured object within the depth of field does not affect the camera's image magnification when the telecentric lens is imaging, t z can be 0, then T can be In this embodiment, t x is the mechanical x-axis coordinate of the center point of the device, t y The mechanical y-axis coordinate of the device midpoint.

[0118] S505 . Determine a conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix, and the third conversion matrix.

[0119] Optionally, since the first transformation matrix represents the transformation matrix from the image coordinate system to the pixel coordinate system, the second transformation matrix represents the transformation matrix from the camera coordinate system to the image coordinate system, and the third transformation matrix represents the transformation matrix between the mechanical coordinate system and the camera coordinate system, it is necessary to inverse transform the first transformation matrix and the second transformation matrix respectively, and determine the transformation matrices of the pixel coordinate system and the mechanical coordinate system based on the inverse transformed matrix and the third transformation matrix.

[0120] S506. Input the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity into the transformation matrix between the pixel coordinate system and the mechanical coordinate system to obtain a target transformation matrix from the pixel coordinate system to the mechanical coordinate system.

[0121] Specifically, the target transformation matrix from the pixel coordinate system to the mechanical coordinate system is used to transform the coordinates of the pixel coordinate system into the coordinates of the mechanical coordinate system.

[0122] In this embodiment, the conversion matrix between the pixel coordinate system and the mechanical coordinate system is determined according to the first conversion matrix from the image coordinate system to the pixel coordinate system, the second conversion matrix from the camera coordinate system to the image coordinate system, and the third conversion matrix between the mechanical coordinate system and the camera coordinate system, and a plurality of project parameters are input into the conversion matrix between the pixel coordinate system and the mechanical coordinate system to obtain a target conversion matrix from the pixel coordinate system to the mechanical coordinate system, thereby being able to control the movement of the object in the mechanical coordinates according to the target conversion matrix from the pixel coordinate system to the mechanical coordinate system based on the image captured by the image acquisition device, thereby achieving more accurate target space positioning and movement control.

[0123] Furthermore, if Fig. 9 As shown, the steps of determining the conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix in the above step S505 are as follows. Fig. 9 It is a flowchart of a method for determining a conversion matrix between a pixel coordinate system and a mechanical coordinate system provided in an embodiment of the present application.

[0124] S901. Determine a first inverse transformation matrix corresponding to a first transformation matrix.

[0125] Optionally, for the first transformation matrix Perform inverse transformation to obtain the first inverse transformation matrix The first inverse transformation matrix represents a transformation matrix from the pixel coordinate system to the image coordinate system.

[0126] S902: Determine a second inverse transformation matrix corresponding to the second transformation matrix.

[0127] Optionally, because the telecentric lens is imaging, the change in the distance between the lens and the measured object within the depth of field does not affect the camera's magnification of the image. Figure 7 , there is a point M(x M ,y M , z M ), there is a point p(x p ,y p), the second transformation matrix can be transformed into formula (7):

[0128]

[0129] in, is the second transformation matrix under the telecentric lens, m is the focal length f and z of the image acquisition device M The second transformation matrix under the telecentric lens is inversely transformed to obtain the second inverse transformation matrix:

[0130] S903 . Determine a conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first inverse conversion matrix, the second inverse conversion matrix, and the third conversion matrix.

[0131] Optionally, since the first inverse transformation matrix is ​​the transformation matrix from the pixel coordinate system to the image coordinate system, the second inverse transformation matrix is ​​the transformation matrix from the graphic coordinate system to the camera coordinate system, and the third transformation matrix is ​​the transformation matrix between the camera coordinate system and the mechanical coordinate system, the transformation matrix between the pixel coordinate system and the mechanical coordinate system can be determined based on the first inverse transformation matrix, the second inverse transformation matrix and the third transformation matrix.

[0132] In this embodiment, the conversion between pixel coordinates and mechanical coordinates is achieved by determining a first conversion inverse matrix and a second conversion inverse matrix, and determining a conversion matrix from a pixel coordinate system to a mechanical coordinate system based on the first conversion inverse matrix, the second conversion inverse matrix and the third conversion matrix.

[0133] Furthermore, the specific process of determining the conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first inverse conversion matrix, the second inverse conversion matrix and the third conversion matrix in the above step S903 is as follows.

[0134] Optionally, the third conversion matrix, the second inverse conversion matrix and the first conversion matrix are multiplied to obtain a conversion matrix between the pixel coordinate system and the mechanical coordinate system.

[0135] Specifically, the third conversion matrix, the second inverse conversion matrix and the first conversion matrix are sequentially multiplied on the left to obtain a conversion matrix between the pixel coordinate system and the mechanical coordinate system.

[0136] The transformation matrix between the pixel coordinate system and the mechanical coordinate system is as follows (8):

[0137]

[0138] in, is the third transformation matrix, is the second inverse transformation matrix, is the first inverse transformation matrix, (x mcs ,y mcs , z mcs) is the mechanical coordinate, α is the telecentricity of the x-axis, β is the telecentricity of the y-axis, t x is the mechanical x-axis coordinate of the center point of the device, t y is the mechanical y-axis coordinate of the center point of the device, z M is the mechanical z-axis coordinate of the center point of the device, m is the ratio of the focal length of the image acquisition device to the mechanical z-axis coordinate of the center point of the device, dx is the mechanical pixel x-axis magnification, dy is the mechanical pixel y-axis magnification, and (u, v) is the pixel coordinate.

[0139] In this embodiment, the transformation matrix between the pixel coordinate system and the mechanical coordinate system is obtained by multiplying the first transformation inverse matrix, the second transformation inverse matrix and the third transformation matrix, so as to accurately position the object in the mechanical coordinate system by combining the imaging principle of the object-side telecentric lens and the camera internal parameters.

[0140] As an optional implementation, refer to Fig.10 As shown, the specific process of determining the moving path of the mask workbench in the above step S204 according to the position of the reference mark plate mark, the position of the mask mark and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system is as follows. Fig.10 It is a flow chart of a method for determining a moving path of a mask workbench provided in an embodiment of the present application.

[0141] S1001. Determine a moving start position according to a position of a mask mark in an image of a measured object and a target conversion matrix between a pixel coordinate system and a mechanical coordinate system.

[0142] The moving starting position is the starting position of the moving path of the mask workbench.

[0143] S1002. Determine the end position of the movement according to the position of the reference mark plate mark in the image of the measured object and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system.

[0144] The moving starting position is the starting position of the moving path of the mask workbench.

[0145] S1003, determining the moving path of the mask workbench according to the moving starting position and the moving ending position.

[0146] As an optional implementation, the moving path of the mask workbench may be determined according to a preset path mode and path expansion / contraction percentage, and based on a moving start position and a moving end position.

[0147] As an optional implementation, in order to ensure that the reference mark plate mark does not move out of the field of view of the image acquisition device during the movement of the mask stage, the movement boundary of the mask stage can be determined by combining the actual field of view of the image acquisition device, the actual size of the reference mark plate mark and the mechanical coordinates of the mask stage, wherein the movement boundary is the position in the mechanical coordinate system. The movement path of the mask stage is determined according to the movement start position, the movement end position and the movement boundary.

[0148] In this embodiment, the starting position and the ending position of the movement are determined according to the position of the mask mark and the position of the reference mark plate mark and the target conversion matrix between the pixel coordinate system and the mechanical coordinate system, and then the moving path of the mask table is determined according to the starting position and the ending position of the movement. Since the target conversion matrix between the pixel coordinate system and the mechanical coordinate system realizes the imaging principle of the object telecentric lens and the effective fusion of the camera parameters, the moving path of the mask table is made more accurate.

[0149] The specific steps of determining the moving start position in the above step S1001 according to the position of the mask mark in the image of the measured object and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system are as follows.

[0150] Optionally, the vector corresponding to the position of the mask mark is multiplied by the target transformation matrix between the pixel coordinate system and the mechanical coordinate system to obtain the moving starting position.

[0151] Optionally, the calculation formula for the moving starting position may be as follows:

[0152]

[0153] Among them, (x mcs1 ,y mcs1 , z mcs1 ) is the mechanical coordinate of the moving start position, (u1, v1) is the pixel coordinate of the position marked by the mask, α is the telecentricity of the x-axis, β is the telecentricity of the y-axis, t x is the mechanical x-axis coordinate of the center point of the device, t y is the mechanical y-axis coordinate of the center point of the device, z M is the mechanical z-axis coordinate of the center point of the device, m is the ratio of the focal length of the image acquisition device to the mechanical z-axis coordinate of the center point of the device, dx is the mechanical pixel x-axis magnification, and dy is the mechanical pixel y-axis magnification. α, β, t x ,t y 、z M , m, dx and dy are all known values.

[0154] In this embodiment, the starting position of movement is obtained by multiplying the vector corresponding to the position of the mask mark with the transformation matrix between the pixel coordinate system and the mechanical coordinate system. Since the transformation matrix between the pixel coordinate system and the mechanical coordinate system realizes the imaging principle of the object-side telecentric lens and the effective fusion of the camera parameters, the obtained starting position of movement of the mechanical coordinates is more accurate.

[0155] As an optional implementation, in actual implementation, when it is necessary to determine the object position in the pixel coordinate system according to the object position in the mechanical coordinate system, the following steps may be performed.

[0156] Optionally, a conversion matrix from the mechanical coordinate system to the pixel coordinate system is determined according to the first conversion matrix, the second conversion matrix and the third conversion matrix.

[0157] Among them, the first transformation matrix is ​​the transformation matrix from the image coordinate system to the pixel coordinate system, the second transformation matrix is ​​the transformation matrix from the camera coordinate system to the image coordinate system, and the third transformation matrix is ​​the transformation matrix from the camera coordinate system to the mechanical coordinate system. Therefore, according to the transformation relationship between the first transformation matrix, the second transformation matrix and the third transformation matrix, the transformation matrix from the mechanical coordinate system to the pixel coordinate system can be determined.

[0158] Optionally, the mark position in the pixel coordinate system is determined based on the conversion matrix from the mechanical coordinate system to the pixel coordinate system, the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity, and the mark position in the mechanical coordinate system.

[0159] Specifically, the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity, and the y-axis telecentricity are input into the conversion matrix from the mechanical coordinate system to the pixel coordinate system to obtain the target conversion matrix from the mechanical coordinate system to the pixel coordinate system. According to the target conversion matrix from the mechanical coordinate system to the pixel coordinate system and the marker position in the mechanical coordinate system, the marker position in the pixel coordinate system is determined.

[0160] Specifically, the vector corresponding to the marker position in the mechanical coordinate system is multiplied by the target transformation matrix from the mechanical coordinate system to the pixel coordinate system to obtain the marker position in the pixel coordinate system.

[0161] In this embodiment, the transformation matrix from the mechanical coordinate system to the pixel coordinate system is determined according to the first transformation matrix, the second transformation matrix and the third transformation matrix, and then the mark position in the pixel coordinate system is determined according to multiple parameters such as telecentricity and the mark position in the mechanical coordinate system, thereby realizing the transformation between the object position in the mechanical coordinate system and the object position in the pixel coordinate system.

[0162] Furthermore, in the above steps, the specific process of determining the conversion matrix from the mechanical coordinate system to the pixel coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix is ​​as follows.

[0163] Optionally, the first conversion matrix, the second conversion matrix and the third conversion matrix are multiplied to obtain a conversion matrix from the mechanical coordinate system to the pixel coordinate system.

[0164] Specifically, the first conversion matrix, the second conversion matrix, and the third conversion matrix are sequentially multiplied on the left to obtain a conversion matrix from the mechanical coordinate system to the pixel coordinate system.

[0165] The transformation matrix from the mechanical coordinate system to the pixel coordinate system is as follows (10):

[0166]

[0167] in, is the first transformation matrix, is the second transformation matrix, is the third conversion matrix, dx is the mechanical pixel x-axis magnification, dy is the mechanical pixel y-axis magnification, f is the focal length of the image acquisition device, α is the x-axis telecentricity, β is the y-axis telecentricity, t x is the mechanical x-axis coordinate of the center point of the device, t y It is the mechanical y-axis coordinate of the center point of the device.

[0168] In this embodiment, by multiplying the first conversion matrix, the second conversion matrix and the third conversion matrix, a conversion matrix from the mechanical coordinate system to the pixel coordinate system is obtained. According to the conversion matrix, more precise positioning from the position in the mechanical coordinate system to the position in the pixel coordinate system can be achieved.

[0169] An embodiment of the present application also provides a marking positioning system based on an object side telecentric lens. The marking positioning system based on the object side telecentric lens includes a control module, an image acquisition device, a mask workbench and a reduced projection lens. The image acquisition device is used to sequentially acquire an image of the object to be measured through the reduced projection lens and the object side telecentric lens. The image of the object to be measured includes the mask mark of the mask on the mask workbench and the reference mark plate mark in the reference mark plate. The image of the object to be measured is sent to the control module. The control module is used to execute the steps of the marking positioning method based on the object side telecentric lens as described above.

[0170] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A marker positioning method based on an object-space telecentric lens, characterized in that: The method comprises: Determine the mechanical pixel x-axis magnification, mechanical pixel y-axis magnification, x-axis telecentricity, and y-axis telecentricity corresponding to the image acquisition device based on the object-space telecentric lens; Determine a target transformation matrix from a pixel coordinate system to a mechanical coordinate system according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, a preset device center point mechanical x-axis coordinate, a preset device center point mechanical y-axis coordinate, a preset device center point mechanical z-axis coordinate, a preset image acquisition device focal length, the x-axis telecentricity, and the y-axis telecentricity; Acquire the position of the reference mark plate mark and the position of the mask mark in the image of the object to be measured sent by the image acquisition device; Determining a movement path of the mask stage according to the position of the reference mark plate mark, the position of the mask mark, and a target transformation matrix between the pixel coordinate system and the mechanical coordinate system; The mask stage is controlled to move according to the mask stage movement path so that the mask mark in the mask set on the mask stage is aligned with the reference mark plate mark in the reference mark plate.

2. The marker positioning method based on the object-space telecentric lens according to claim 1, characterized in that: The method of determining a target transformation matrix from a pixel coordinate system to a mechanical coordinate system according to the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, a preset device center point mechanical x-axis coordinate, a preset device center point mechanical y-axis coordinate, a preset device center point mechanical z-axis coordinate, a preset image acquisition device focal length, an x-axis telecentricity, and a y-axis telecentricity includes: Establish pixel coordinate system, image coordinate system, camera coordinate system and mechanical coordinate system; Establishing a first transformation matrix from the image coordinate system to the pixel coordinate system; Establishing a second transformation matrix from the camera coordinate system to the image coordinate system; Establishing a third transformation matrix between the mechanical coordinate system and the camera coordinate system; Determine a conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix; The mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset device center point mechanical z-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity are input into the transformation matrix between the pixel coordinate system and the mechanical coordinate system to obtain a target transformation matrix from the pixel coordinate system to the mechanical coordinate system.

3. The marker positioning method based on the object-space telecentric lens according to claim 2, characterized in that: The step of establishing a first transformation matrix from the image coordinate system to the pixel coordinate system comprises: The position coordinates of the origin of the image coordinate system in the pixel coordinate system are set to preset values, and a first conversion matrix from the image coordinate system to the pixel coordinate system is obtained.

4. The marker positioning method based on the object-space telecentric lens according to claim 2, characterized in that: Determining the conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion matrix, the second conversion matrix and the third conversion matrix includes: Determine a first inverse transformation matrix corresponding to the first transformation matrix; Determine a second inverse transformation matrix corresponding to the second transformation matrix; A conversion matrix between the pixel coordinate system and the mechanical coordinate system is determined according to the first inverse conversion matrix, the second inverse conversion matrix and the third conversion matrix.

5. The marker positioning method based on the object-space telecentric lens according to claim 4, characterized in that: Determining the conversion matrix between the pixel coordinate system and the mechanical coordinate system according to the first conversion inverse matrix, the second conversion inverse matrix and the third conversion matrix includes: Multiplying the third conversion matrix, the second inverse conversion matrix and the first conversion matrix to obtain a conversion matrix between the pixel coordinate system and the mechanical coordinate system; Among them, the transformation matrix between the pixel coordinate system and the mechanical coordinate system is: in, is the third transformation matrix, is the second transformation inverse matrix, is the first inverse transformation matrix, α is the x-axis telecentricity, β is the y-axis telecentricity, t x is the mechanical x-axis coordinate of the center point of the device, t y is the mechanical y-axis coordinate of the center point of the device, z M is the mechanical z-axis coordinate of the center point of the device, m is the ratio of the focal length of the image acquisition device to the mechanical z-axis coordinate of the center point of the device, dx is the mechanical pixel x-axis magnification, and dy is the mechanical pixel y-axis magnification.

6. The marker positioning method based on the object-space telecentric lens according to claim 1, characterized in that: The step of determining the movement path of the mask table according to the position of the reference mark plate mark, the position of the mask mark, and the target conversion matrix between the pixel coordinate system and the mechanical coordinate system comprises: Determine a moving start position according to the position of the mask mark in the image of the measured object and a target transformation matrix between the pixel coordinate system and the mechanical coordinate system; Determining the end position of movement according to the position of the reference mark plate mark in the image of the measured object and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system; The moving path of the mask working table is determined according to the moving starting position and the moving ending position.

7. The marker positioning method based on the object-space telecentric lens according to claim 6, characterized in that: The step of determining the moving start position according to the position of the mask mark in the image of the object to be measured and the target transformation matrix between the pixel coordinate system and the mechanical coordinate system comprises: The moving start position is obtained by multiplying the vector corresponding to the position of the mask mark with the target transformation matrix between the pixel coordinate system and the mechanical coordinate system.

8. The marker positioning method based on the object-side telecentric lens according to any one of claims 1 to 7, characterized in that: The method further comprises: Determine a conversion matrix from a mechanical coordinate system to a pixel coordinate system according to the first conversion matrix, the second conversion matrix, and the third conversion matrix; The mark position in the pixel coordinate system is determined according to the conversion matrix from the mechanical coordinate system to the pixel coordinate system, the mechanical pixel x-axis magnification, the mechanical pixel y-axis magnification, the preset device center point mechanical x-axis coordinate, the preset device center point mechanical y-axis coordinate, the preset image acquisition device focal length, the x-axis telecentricity and the y-axis telecentricity, and the mark position in the mechanical coordinate system.

9. The marker positioning method based on the object-space telecentric lens according to claim 8, characterized in that: The step of determining a conversion matrix from a mechanical coordinate system to a pixel coordinate system according to the first conversion matrix, the second conversion matrix, and the third conversion matrix includes: Multiplying the first conversion matrix, the second conversion matrix and the third conversion matrix to obtain a conversion matrix from a mechanical coordinate system to a pixel coordinate system; Among them, the transformation matrix from the mechanical coordinate system to the pixel coordinate system is: in, is the first transformation matrix, is the second transformation matrix, is the third conversion matrix, dx is the mechanical pixel x-axis magnification, dy is the mechanical pixel y-axis magnification, f is the focal length of the image acquisition device, α is the x-axis telecentricity, β is the y-axis telecentricity, t x is the mechanical x-axis coordinate of the center point of the device, t y It is the mechanical y-axis coordinate of the center point of the device.

10. A marker positioning system based on an object-space telecentric lens, characterized in that: The mark positioning system based on the object-side telecentric lens includes a control module, an image acquisition device, a mask workbench and a reduced projection lens. The image acquisition device is used to obtain an image of the object to be measured through the reduced projection lens and the object-side telecentric lens in sequence, and the image of the object to be measured includes the mask mark of the mask on the mask workbench and the reference mark plate mark in the reference mark plate, and the image of the object to be measured is sent to the control module. The control module is used to execute the steps of the mark positioning method based on the object-side telecentric lens as described in any one of claims 1 to 9.

Images