Calibration method of electron beam measuring equipment and related product

Abstract

The invention provides a calibration method of electron beam measuring equipment and a related product. The calibration method comprises the following steps: acquiring an initial scanning image of a wafer acquired by the electron beam measurement equipment at an initial position in a preset view field; controlling the wafer to move for a preset distance along a preset direction, and acquiring a translation scanning image acquired for the wafer under the condition of keeping the preset field of view unchanged; determining a first position coordinate of each positioning mark in the initial scanning image and a second position coordinate of each positioning mark in the translation scanning image; obtaining a distortion model of the electron beam measurement equipment according to the displacement of the second position coordinates and the first position coordinates of the positioning marks in the preset direction; and calibrating the electron beam measuring equipment by using the distortion model. According to the method, the distortion degree of the scanned image of the electron beam measurement equipment can be reduced, and the measurement precision of the electron beam measurement equipment is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor testing technology, and in particular to a calibration method for an electron beam measurement device, a computer-readable storage medium, a computer program product, and an electron beam measurement device. Background Technology

[0002] In the chip manufacturing process, critical dimension measurement and defect detection are crucial aspects of integrated circuit yield management. Related technologies typically use electron beam metrology equipment (such as scanning electron microscopes) to inspect wafers and detect defects promptly during wafer manufacturing.

[0003] Electron beam metrology equipment typically uses scanning coils to control the electron beam to scan within the field of view to obtain the inspection image of the wafer. Due to the inherent limitations of the electron gun scanning structure and control mechanism, the deflection of the electron beam will change nonlinearly under a large field of view, resulting in nonlinear shifts in the pixels of the inspection image, especially the pixels at the edges of the field of view, where the distortion is more severe.

[0004] Image distortion can affect the measurement accuracy of electron beam measurement equipment. Summary of the Invention

[0005] One object of the present invention is to provide a calibration method, a computer-readable storage medium, a computer program product, and an electron beam measurement device for calibrating the electron beam measurement device, reducing the degree of distortion of the scanned image, thereby improving the measurement accuracy of the electron beam measurement device.

[0006] Specifically, according to one aspect of the present invention, the present invention provides a calibration method for an electron beam measurement device, comprising: An initial scan image of the wafer is acquired by an electron beam gauging device at an initial position with a preset field of view; the wafer is provided with multiple positioning marks; The wafer is controlled to move a preset distance along a preset direction, and while keeping the preset field of view unchanged, a translational scan image of the wafer is acquired; Determine the first position coordinates of each of the positioning marks in the initial scan image, and the second position coordinates in the translational scan image; Based on the displacement of the second position coordinates and the first position coordinates of each of the positioning marks in the preset direction, the distortion model of the electron beam measurement device is obtained. The distortion model reflects the distortion of pixels at different positions in the preset direction in the scanned image of the electron beam measurement device in the preset direction. The electron beam measurement device is calibrated using the distortion model.

[0007] Optionally, obtaining the distortion model of the electron beam measurement device based on the displacement of the second position coordinates and the first position coordinates of each of the positioning marks in the preset direction includes: The first coordinate value of each first position coordinate on the first coordinate axis and the second coordinate value of each second position coordinate on the first coordinate axis are obtained respectively, wherein the preset direction is a direction parallel to the first coordinate axis; The difference between the second coordinate value and the first coordinate value of each of the positioning marks is calculated and used as the displacement. Subtract the preset distance from each of the displacements to obtain the offset; Based on each of the offsets and the corresponding first coordinate values, the cumulative offset of each positioning mark and the preset positioning mark in the direction of the first coordinate axis is calculated respectively; The cumulative offset data corresponding to each of the first coordinate values ​​is fitted with a function, and the resulting function relating the cumulative offset to the coordinate values ​​of the first coordinate axis is used as the distortion model.

[0008] Optionally, the step of calculating the cumulative offset between each positioning mark and the preset positioning mark in the first coordinate axis direction based on each offset and the corresponding first coordinate value includes: Discrete numerical integration is performed with the coordinates of the first coordinate axis as the independent variable and the offset as the dependent variable. The integration result is taken as the cumulative offset corresponding to the first coordinate value, with each first coordinate value as the upper limit of integration.

[0009] Optionally, the plurality of positioning marks are spaced apart in the preset direction with the preset distance as the spacing.

[0010] Optionally, the distance between the two farthest positioning marks is greater than the width of the preset field of view.

[0011] Optionally, the preset direction is the line scanning direction of the electron beam measurement device.

[0012] Optionally, calibrating the electron beam measurement device using the distortion model includes: According to the distortion model, the scanning signal of the electron beam measurement device is compensated so that the electron beam measurement device can acquire a calibrated scanning image. The scanning signal is used to control the scanning coil of the electron beam measurement device during the scanning process to adjust the deflection of the electron beam.

[0013] Optionally, calibrating the electron beam measurement device using the distortion model includes: The scanned images acquired by the electron beam measurement device are calibrated according to the distortion model to obtain calibrated scanned images.

[0014] According to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of the calibration method of any of the above-described electron beam measurement devices.

[0015] According to another aspect of the present invention, a computer program product is also provided, comprising a computer program that, when executed by a processor, implements the steps of the calibration method for any of the electron beam measurement devices described above.

[0016] According to another aspect of the present invention, an electron beam measurement device is also provided, the electron beam measurement device including a scanning coil and a controller, the controller including a memory, a processor and a computer program stored in the memory, and the processor executing the computer program to implement the steps of the calibration method of the electron beam measurement device described above.

[0017] The calibration method for the electron beam metrology equipment of the present invention involves moving the wafer a preset distance along a preset direction, and using this preset distance as a reference, comparing it with the displacement of the same positioning mark in the preset direction in the initial scan image and the translational scan image. This yields a distortion model reflecting the distortion of the scan image in the preset direction. By calibrating the electron beam metrology equipment using this distortion model, the degree of distortion in the scan image of the electron beam metrology equipment is reduced, thereby improving the measurement accuracy of the electron beam metrology equipment.

[0018] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0019] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic flowchart of a calibration method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of acquiring an initial scan image in a calibration method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of acquiring translational scan images using a calibration method according to an embodiment of the present invention; Figure 4This is a schematic diagram of the process for obtaining a distortion model according to another embodiment of the present invention; Figure 5 This is a schematic diagram of a calibration method according to an embodiment of the present invention, which performs function fitting on the data of the cumulative offset corresponding to the first coordinate value; Figure 6 This is a schematic diagram of an electron beam measurement device according to an embodiment of the present invention; Figure 7 This is a schematic diagram of a computer program product according to an embodiment of the present invention; Figure 8 This is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention. Detailed Implementation

[0020] The purpose of the calibration method for the electron beam measurement equipment in this embodiment is to calibrate the electron beam measurement equipment, reduce the distortion of the scanned images obtained by the electron beam measurement equipment, and thereby improve the measurement accuracy of the electron beam measurement equipment.

[0021] Figure 1 This is a schematic flowchart of a calibration method for an electron beam measurement device according to an embodiment of the present invention. The method generally includes: S100: Acquire the initial scan image of the wafer from the electron beam measurement device at the initial position with a preset field of view; the wafer is equipped with multiple positioning marks; S200 controls the wafer to move a preset distance along a preset direction, and acquires a translational scan image of the wafer while keeping the preset field of view unchanged; S300, determine the first position coordinates of each positioning mark in the initial scan image, and the second position coordinates in the translation scan image; S400: Based on the displacement of the second position coordinates and the first position coordinates of each positioning mark in the preset direction, the distortion model of the electron beam measurement device is obtained. The distortion model reflects the distortion of pixels at different positions in the preset direction in the scanned image of the electron beam measurement device. The S500 uses a distortion model to calibrate electron beam measurement equipment.

[0022] Electron beam metrology equipment can be a scanning electron microscope (SEM), a transmission electron microscope (TEM), or similar instruments. The object to be measured can be a semiconductor device, such as a wafer. Electron beam metrology equipment can be used to measure critical dimensions during wafer manufacturing and to detect wafer manufacturing defects.

[0023] Taking a scanning electron microscope (SEM) as an example, an SEM typically includes components such as an electron source, condenser lens, scanning coil, aperture, objective lens, sample stage, and detector. The electron source emits an electron beam. When the electron beam illuminates a point on the surface of the wafer to be inspected, it excites secondary electrons and backscattered electrons, generating physical signals. These signals are collected and amplified by the detector to obtain a pixel image of that point. The SEM typically uses scanning signals to control the scanning coil, adjusting the deflection of the electron beam to scan a specific area on the wafer surface and acquire a scanned image of that area. During the scanning process, the left-to-right scanning motion of the electron beam on the sample stage plane or wafer plane is called line scanning or horizontal scanning, while the top-to-bottom scanning motion is called frame scanning or vertical scanning. The scanning speeds differ; line scanning is generally faster than frame scanning.

[0024] Due to the inherent limitations of the electron gun scanning structure and control mechanism, under a large field of view, the deflection of the electron beam and its scanning step size on the sample stage plane or wafer plane are not strictly linearly related. This results in nonlinear shifts in the pixels of the acquired scanned image, especially the pixels at the edge of the field of view, where the distortion is more severe.

[0025] In this embodiment, the wafer can be a pre-manufactured sample, and multiple positioning marks are etched on the wafer at intervals. The positioning marks can be dots, crosshairs, circles, etc. When the positioning mark is a dot, the position coordinates of the dot in the acquired scanned image can be used as the position coordinates of the positioning mark. When the positioning mark is a crosshair, the position coordinates of the crosshair intersection in the scanned image can be used as the position coordinates of the positioning mark. When the positioning mark is a circle, an image recognition algorithm can be used to determine the centroid of the circle in the scanned image, and the position coordinates of the centroid can be used as the position coordinates of the positioning mark.

[0026] The preset direction can be a scanning direction of the electron beam, such as a line scan direction. The preset distance can be set according to the parameters of the scanning electron microscope. For example, the preset distance can be set to about 2% of the width corresponding to the preset field of view. For instance, when the preset field of view of the scanning electron microscope is 10000*800nm ​​(this size is the size of the scanned image), the preset distance can be set to 200nm (corresponding to a width of 10000nm). In this way, the distortion of the scanned image at 2% of the preset field of view width can be obtained, improving the accuracy of subsequent calibration.

[0027] It is important to understand that, due to the inherent limitations of the electron gun scanning structure and control mechanism, both the initial scan image and the translational scan image will exhibit inherent nonlinear distortion in a preset direction. Conventionally, it is not possible to calibrate an electron beam measurement device by comparing two images with nonlinear distortion. The inventors of this application have overcome this conventional thinking and cleverly utilized the inherent nonlinear distortion in both the initial scan image and the translational scan image to design this calibration method: by moving the wafer a preset distance along a preset direction, and using this preset distance as a reference, the displacement of the same positioning mark in the preset direction in the initial scan image and the translational scan image is compared, thereby obtaining the distortion of the scan image in the preset direction.

[0028] The following explanation uses the X-axis as the preset direction and a preset distance of 200nm as an example. Please refer to... Figure 2-3 , Figure 2 This is a schematic diagram for acquiring the initial scan image. Figure 3 This is a schematic diagram for acquiring translational scan images. Figure 2-3 In the process, multiple positioning marks 62 are set on the wafer 61, and the preset field of view 53 of the electron beam measurement device has a width of W along the preset direction and a height of L along the preset direction. Figure 3 Wafer 61 in the middle is Figure 2 The position of wafer 61 shifted 200nm to the right.

[0029] During calibration, an electron beam calibrator is used to acquire scan images of the wafer before and after it has moved 200 nm along the X-axis, using the same field of view. Ideally, the displacement of any positioning mark on the wafer along the X-axis in both the initial scan image and the translational scan image should be equal to 200 nm. However, due to nonlinear distortion in the X-axis direction of the scan images, the displacement of each positioning mark may deviate by approximately 200 nm, and the degree of deviation relative to 200 nm may also differ for positioning marks at different positions along the X-axis.

[0030] Generally, the distortion of pixels at the edge of the field of view is more severe. That is, the displacement of the positioning mark at the edge of the scanned image (such as the positioning mark near X-axis coordinate 0 or 10000) relative to 200nm will be greater than that of the positioning mark at the center of the scanned image (such as the positioning mark near X-axis coordinate 5000).

[0031] By calculating the displacement of positioning marks at different positions on the X-axis relative to 200 nm, and then performing data fitting (e.g., polynomial fitting), a distortion model of the electron beam measurement device can be obtained. This distortion model reflects the distortion of pixels at any position on the X-axis in the X-axis direction. Using this distortion model, the electron beam measurement device can be calibrated to obtain a calibrated scan image.

[0032] The calibration method for the electron beam metrology equipment in this embodiment involves moving the wafer a preset distance along a preset direction and using this preset distance as a reference. The displacement of the same positioning mark in the preset direction in the initial scan image and the translated scan image is compared to obtain a distortion model reflecting the distortion of the scan image in the preset direction. By calibrating the electron beam metrology equipment using this distortion model, the degree of distortion in the scan image of the electron beam metrology equipment is reduced, thereby improving the measurement accuracy of the electron beam metrology equipment.

[0033] In some embodiments of the calibration method of the present invention, such as Figure 4 As shown, based on the displacement of the second and first position coordinates of each positioning mark in a preset direction, the distortion model of the electron beam measurement device is obtained, including: S411, respectively obtain the first coordinate value of each first position coordinate on the first coordinate axis, and the second coordinate value of each second position coordinate on the first coordinate axis, with the preset direction being the direction parallel to the first coordinate axis; S413, calculate the difference between the second coordinate value and the first coordinate value of each positioning mark, and use it as the displacement; S415, subtract the preset distance from each displacement to obtain the offset; S417, Based on each offset and the corresponding first coordinate value, calculate the cumulative offset of each positioning mark and the preset positioning mark in the first coordinate axis direction; S419, perform function fitting on the cumulative offset data corresponding to each first coordinate value, and use the obtained function on the change of cumulative offset with the coordinate value of the first coordinate axis as the distortion model.

[0034] In this embodiment, the first coordinate axis can be the X-axis, and the preset direction can be parallel to the X-axis and point in the direction that increases along the X-axis. By setting the first coordinate axis along the preset direction, in subsequent calculations, only the coordinate values ​​of the position coordinates on the first coordinate axis need to be used, thereby simplifying the calculation process. For example, the preset direction can be the line scan direction to calibrate distortions in the line scan direction. The preset direction can also be the frame scan direction to calibrate distortions in the frame scan direction.

[0035] In this embodiment, the offset corresponding to different first coordinate values ​​can be positive or negative. The offset reflects the distortion caused when the first coordinate value deviates from the preset distance in the direction of the first coordinate axis. That is to say, the magnitude of the offset corresponding to each first coordinate value is related to both the magnitude of the preset distance and the magnitude of the first coordinate value itself.

[0036] The preset positioning marker can be the positioning marker corresponding to the smallest of the first coordinate values, the positioning marker corresponding to the largest of the first coordinate values, or the positioning marker corresponding to the first coordinate value that serves as the median. In order for the distortion model to reflect the distortion of pixels corresponding to different coordinate values ​​of the first coordinate axis in the scanned image, it is necessary to calculate the cumulative offset of the pixel at each first coordinate value relative to the preset positioning marker in the direction of the first coordinate axis.

[0037] For example, the positioning marker corresponding to the smallest of the first coordinate values ​​is used as the preset positioning marker. When calculating the cumulative offset, the traversal starts from the left edge of the first coordinate axis direction of the scanned image. For each first coordinate value encountered, the offsets corresponding to all first coordinate values ​​to the left of that first coordinate value (i.e., all first coordinate values ​​less than that first coordinate value) are summed, and the result is used as the cumulative offset corresponding to that first coordinate value. In this way, a discrete dataset including each first coordinate value and its corresponding cumulative offset is obtained.

[0038] Next, by performing function fitting (e.g., multi-top fitting) on ​​the above discrete dataset, we obtain a continuous function curve of the cumulative offset as a function of the coordinate values ​​of the first coordinate axis, which is the distortion model.

[0039] In some embodiments of the calibration method of the present invention, based on each offset and the corresponding first coordinate value, the cumulative offset between each positioning mark and the preset positioning mark in the first coordinate axis direction is calculated, including: Discrete numerical integration is performed with the coordinates of the first coordinate axis as the independent variable and the offset as the dependent variable. The upper limit of integration is set for each first coordinate value, and the integrated result is used as the cumulative offset corresponding to the first coordinate value.

[0040] In this embodiment, the cumulative offset of the pixel at each first coordinate value along the first coordinate axis is calculated using discrete numerical integration. The example will still use the positioning mark corresponding to the smallest of the first coordinate values ​​as the preset positioning mark. When calculating the discrete numerical integration, the traversal begins from the left edge of the first coordinate axis of the scanned image. For each traversed first coordinate value, the offsets corresponding to all first coordinate values ​​to the left of that first coordinate value are discretely integrated. In each discrete numerical integration, the coordinate value of the first coordinate axis is used as the independent variable, the offset as the dependent variable, the smallest first coordinate value as the lower limit of integration, and the traversed first coordinate value as the upper limit of integration. Discrete numerical integration can be calculated using methods such as the rectangular method or interpolation; no specific method is applied here.

[0041] By using discrete numerical integration to calculate the cumulative offset corresponding to each first coordinate value, the cumulative offset data incorporates information on the displacement along the first coordinate axis, thereby improving the calibration effect.

[0042] In some embodiments of the calibration method of the present invention, a fourth-order polynomial is used to perform function fitting on the data of the cumulative offset corresponding to each first coordinate value to obtain a distortion model.

[0043] Please refer to Figure 5 In the figure, the horizontal axis is the first coordinate axis, the vertical axis is the cumulative offset, and the dashed line is the fourth-order polynomial curve obtained by fitting.

[0044] The inventors of this application collected a large amount of experimental data and used various polynomials for fitting and verification. After analysis, they found that the fourth-order polynomial can more accurately reflect the change of the cumulative offset with the coordinate value of the first coordinate axis, and the resulting distortion model can more accurately calibrate the electron beam measurement equipment.

[0045] In some embodiments of the calibration method of the present invention, after determining the first position coordinates of each positioning mark in the initial scanned image and the second position coordinates in the translated scanned image, the method further includes: Using the translational scan image as the new initial scan image, the wafer is again controlled to move a preset distance along a preset direction, and while keeping the preset field of view unchanged, a new translational scan image of the wafer is acquired. Using the position coordinates of each positioning mark in the new initial scan image as the first position coordinates, the second position coordinates of each positioning mark in the new translational scan image are determined.

[0046] In this embodiment, by moving the wafer multiple times at a preset distance and acquiring scanned images, the amount of discrete dataset can be increased, thereby improving the accuracy of function fitting.

[0047] In some embodiments of the calibration method of the present invention, the positioning marks are closed shapes such as circles and squares.

[0048] For example, such as Figure 2-3 As shown, when the positioning mark 62 is a circle, an image recognition algorithm (such as the Centroid Algorithm, or COG algorithm for short) can be used to determine the centroid of the circle in the scanned image, and the position coordinates of the centroid are used as the position coordinates of the positioning mark.

[0049] It's important to understand that when using dots or crosshairs as positioning markers, individual pixels at the intersections of dots or crosshairs may experience random pixel drift, leading to inaccurate position coordinates that don't accurately reflect the marker's location. Using closed shapes as positioning markers, however, involves referencing the entire closed region during centroid determination. This reduces the impact of pixel drift, resulting in more accurate overall positioning coordinates and improved calibration precision.

[0050] In some embodiments of the calibration method of the present invention, such as Figure 2-3 As shown, multiple positioning marks 62 are spaced apart in a preset direction at a preset distance D. This facilitates the determination of the position of each positioning mark in the translational scan image, improving calibration efficiency.

[0051] In some embodiments of the calibration method of the present invention, such as Figure 2-3 As shown, in the preset direction, the distance between the two furthest positioning marks 62 is greater than the width W of the preset field of view. This ensures that positioning marks exist near both edges of the initial scanned image and the translated scanned image in the preset direction, thereby providing data acquisition near the edges of the scanned image and improving the calibration effect on the scanned image edges.

[0052] In some embodiments of the calibration method of the present invention, the positioning mark 62 is a circle, and multiple positioning marks 62 are spaced apart in a preset direction at a preset distance D, and the diameter of the positioning mark 62 is 1 / 3 to 2 / 3 of the preset distance. This ensures that the circular image occupies 1 / 3 to 2 / 3 of the preset distance in the scanned image. During the determination of the centroid of the circular image, the coordinates of pixels in a larger area are calculated, allowing the determined position coordinates to further reduce the influence of pixel drift, accurately reflecting the position of the positioning mark as a whole, and thus improving the subsequent calibration accuracy.

[0053] In some embodiments of the calibration method of the present invention, the preset direction is the line scanning direction of the electron beam measurement device.

[0054] When acquiring scanned images with a large field of view, the field width in the horizontal scanning direction is usually large, which easily leads to nonlinear distortion in the horizontal scanning direction. On the other hand, in order to improve the acquisition speed, the scanning speed in the horizontal scanning direction is relatively fast, which further aggravates the nonlinear distortion in the horizontal scanning direction. By setting the preset direction as the horizontal scanning direction of the electron beam measurement device, distortion calibration in the horizontal scanning direction can be achieved, thereby improving the measurement accuracy of the electron beam measurement device.

[0055] In some embodiments of the calibration method of the present invention, the electron beam measurement equipment is calibrated using a distortion model, including: Based on the distortion model, the scanning signal of the electron beam measurement device is compensated so that the electron beam measurement device can acquire a calibrated scanning image. The scanning signal is used to control the scanning coil of the electron beam measurement device during the scanning process to adjust the deflection of the electron beam.

[0056] In this embodiment, by using a distortion model to compensate for the scanning signal of the electron beam metrology equipment, the equipment scans the wafer with a calibrated electron beam and directly outputs the calibrated scan image. This approach significantly improves measurement efficiency while enhancing the measurement accuracy of the electron beam metrology equipment.

[0057] In some embodiments of the calibration method of the present invention, the electron beam measurement equipment is calibrated using a distortion model, including: Based on the distortion model, the scanned images acquired by the electron beam measurement equipment are calibrated to obtain calibrated scanned images. This approach allows for more flexible processing of scanned images and improves the measurement accuracy of the electron beam measurement equipment.

[0058] The flowchart provided in this embodiment is not intended to indicate that the operations of the method will be performed in any particular order, or that all operations of the method are included in every case. Furthermore, the method may include additional operations. Within the scope of the technical concept provided by the method in this embodiment, additional variations can be made to the above method.

[0059] It should be understood that in some embodiments, the components may be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods may be implemented using software or firmware stored in memory and executed by a suitable instruction execution system.

[0060] This invention also provides a computer program product 10, a computer-readable storage medium 20, and an electron beam measurement device 50. Figure 7 This is a schematic diagram of a computer program product 10 according to an embodiment of the present invention. Figure 8 This is a schematic diagram of a computer-readable storage medium 20 according to an embodiment of the present invention. Figure 6This is a schematic diagram of an electron beam measurement device 50 according to an embodiment of the present invention. The computer program product 10 includes a computer program 11, which, when executed by the processor 32, implements the steps of the calibration method for the electron beam measurement device described above. A computer-readable storage medium 20 stores the computer program 11 thereon, which, when executed by the processor 32, implements the steps of the calibration method for the electron beam measurement device described above. The electron beam measurement device 50 may include a scanning coil 51 and a controller 52. The controller 52 includes a memory 31, a processor 32, and the computer program 11 stored in the memory 31. When the processor 32 executes the computer program, it implements the steps of the calibration method for the electron beam measurement device described above.

[0061] The computer program 11 used to perform the operations of this invention may be assembly instructions, Instruction Set Architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, integrated circuit configuration data, or source code or object code written in any combination of one or more programming languages ​​and procedural programming languages. The computer program 11 may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a Local Area Network (LAN) or Wide Area Network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of this invention, electronic circuits, including, for example, programmable logic circuits, Field-Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), may execute computer-readable program instructions to personalize the electronic circuits by utilizing state information from computer-readable program instructions.

[0062] For the purposes of this embodiment, computer program product 10 is a related product that includes computer program 11.

[0063] For the purposes of this embodiment, the computer-readable storage medium 20 is a tangible device capable of holding and storing a computer program 11. It can be any device capable of containing, storing, communicating, propagating, or transmitting the computer program 11 for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable storage medium 20 include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable optical disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, floppy disk, mechanical encoding device, and any suitable combination thereof.

[0064] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method of calibrating an e-beam metrology apparatus, characterized by, The method comprises: acquiring an initial scanning image of a wafer collected by an electron beam measurement device at an initial position with a preset field of view; the wafer is provided with a plurality of positioning marks; controlling the wafer to move a preset distance along a preset direction, and acquiring a translation scanning image of the wafer collected while keeping the preset field of view unchanged; determining first position coordinates of each positioning mark in the initial scanning image and second position coordinates of each positioning mark in the translation scanning image; obtaining a distortion model of the electron beam measurement device according to a displacement of the second position coordinates and the first position coordinates of each positioning mark in the preset direction, the distortion model reflecting a distortion of pixel points in different positions in the preset direction in a scanning image of the electron beam measurement device; calibrating the electron beam measurement device by using the distortion model.

2. The calibration method of claim 1, wherein, The method of obtaining a distortion model of the electron beam measurement device according to a displacement of the second position coordinates and the first position coordinates of each positioning mark in the preset direction comprises: respectively acquiring a first coordinate value of each first position coordinate on a first coordinate axis and a second coordinate value of each second position coordinate on the first coordinate axis, the preset direction being parallel to the first coordinate axis; respectively calculating a difference value between the second coordinate value and the first coordinate value of each positioning mark as the displacement; respectively subtracting the preset distance from each displacement to obtain an offset; respectively calculating a cumulative offset of each positioning mark and a preset positioning mark in the first coordinate axis direction based on each offset and the corresponding first coordinate value; performing function fitting on data of the cumulative offset corresponding to each first coordinate value, and taking a function about the cumulative offset changing with the coordinate value of the first coordinate axis as the distortion model.

3. The method of calibration of claim 2, wherein, The method of respectively calculating a cumulative offset of each positioning mark and a preset positioning mark in the first coordinate axis direction based on each offset and the corresponding first coordinate value comprises: performing discrete numerical integration with the coordinate value of the first coordinate axis as the independent variable and the offset as the dependent variable, wherein each first coordinate value is taken as the upper limit of integration, and the integral result is taken as the cumulative offset corresponding to the first coordinate value.

4. The method of calibration of claim 1, wherein, The plurality of positioning marks are arranged at intervals in the preset direction with the preset distance as the interval.

5. The method of calibration of claim 4, wherein, The distance between the two positioning marks farthest apart is greater than the width of the preset field of view.

6. The method of calibration of claim 1, wherein, The preset direction is the line scanning direction of the electron beam measurement device.

7. The method of calibration of claim 1, wherein, The method of calibrating the electron beam measurement device by using the distortion model comprises: compensating a scanning signal of the electron beam measurement device according to the distortion model, so that the electron beam measurement device acquires a calibrated scanning image, the scanning signal being used to control a scanning coil of the electron beam measurement device in a scanning process to adjust the deflection amount of an electron beam; or According to the distortion model, a scanning image collected by the electron beam measurement device is calibrated to obtain a calibrated scanning image.

8. A computer-readable storage medium, characterized in that, A computer program is stored thereon, and the computer program, when executed by a processor, implements the steps of the calibration method of the electron beam measurement device according to any one of claims 1 to 7.

9. A computer program product comprising a computer program, characterized in that, The computer program, when executed by a processor, implements the steps of the calibration method of the electron beam measurement device according to any one of claims 1 to 7.

10. An e-beam metrology apparatus, characterized in that, The computer program, when executed by a processor, implements the steps of the calibration method of the electron beam measurement device according to any one of claims 1 to 7. The computer program, when executed by a processor, implements the steps of the calibration method of the electron beam measurement device according to any one of claims 1 to 7.

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