Calibration structure
By forming calibration marks with different reflectivities on the wafer, the problem that existing calibration boards cannot be used to calibrate imaging systems with high magnification is solved, achieving efficient and accurate calibration results.
Patent Information
- Application Number
- CN202423238066.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2034-12-26
AI Technical Summary
Existing calibration plates are too large to be effectively calibrated for imaging systems with high magnification.
Calibration marks are formed on the wafer, and different colors of calibration marks are formed by utilizing the reflectivity difference between the first and second feature structures. Combined with the polygonal arrangement on the wafer, a smaller size calibration mark is achieved, which is suitable for imaging systems with high magnification.
It enables high-precision calibration of imaging systems with large magnification, improves calibration efficiency and accuracy, and reduces the influence of aberrations.
Smart Images
Figure CN223580927U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of microscopic imaging, in particular to a calibration structure. BACKGROUND
[0002] At present, a calibration board can be used to calibrate an imaging system, so as to determine the conversion relationship between the physical size and the pixels of the imaging system. However, the current calibration board is large in size, and cannot be used to calibrate an imaging system with a large magnification. CONTENT OF THE INVENTION
[0003] Therefore, the present application aims to provide a calibration structure, which forms calibration marks on a wafer, and can realize calibration marks with a small size, and is beneficial to calibrate an imaging system with a large magnification. The specific scheme is as follows:
[0004] In one aspect, the present application provides a calibration structure, which comprises a wafer and calibration marks on the wafer, the calibration marks having first feature structures and second feature structures arranged at intervals, the first feature structures being first film layers on the wafer, and the second feature structures being second film layers on the wafer.
[0005] The reflectivity of the first feature structures and the second feature structures is different, so that the first feature structures and the second feature structures are of different colors.
[0006] Optionally, the first feature structures and the second feature structures have flush upper surfaces, and the first film layers and the second film layers have the same thickness.
[0007] Optionally, the wafer comprises a plurality of calibration regions, and each calibration region is provided with the calibration marks.
[0008] Optionally, a target region of the plurality of calibration regions is provided with a plurality of calibration marks, the first feature structures in the plurality of calibration marks are different in size, and the plurality of calibration marks correspond to imaging systems with different magnifications.
[0009] Optionally, the imaging systems with different magnifications comprise a first imaging system with a first magnification and a second imaging system with a second magnification, when the first magnification is greater than the second magnification, the feature pattern of the first feature structures in the calibration marks corresponding to the first imaging system is smaller than the feature pattern of the first feature structures in the calibration marks corresponding to the second imaging system.
[0010] Optionally, the first magnification is 200 microns, and the second magnification is 20, and the size of the feature pattern of the first feature structure in the calibration mark corresponding to the second imaging system is 1 millimeter.
[0011] Optionally, the size of the feature pattern of the first feature structure and the second feature structure ranges from 0.8 microns to 5000 microns.
[0012] Optionally, the first feature structure and the second feature structure are periodically arranged in a first direction x and a second direction y; in one calibration mark, the number of arrangements of the first feature structure in the first direction x is greater than or equal to 3, and the number of arrangements of the first feature structure in the second direction y is greater than or equal to 3.
[0013] Optionally, the shape of the feature pattern of the first feature structure and the second feature structure is a polygon.
[0014] Optionally, the first direction x and the second direction y are perpendicular, and the shape of the feature pattern of at least one of the first feature structure and the second feature structure is a square.
[0015] Optionally, the contrast of the first feature structure and the second feature structure is greater than a preset value.
[0016] The embodiment of the present application provides a calibration structure, which can include a wafer and a calibration mark on the wafer. The calibration mark has a first feature structure and a second feature structure arranged at intervals. The first feature structure is a first film layer on the wafer, and the second feature structure is a second film layer on the wafer. The reflectivity of the first feature structure and the second feature structure is different, so that the first feature structure and the second feature structure are different in color, thereby distinguishing the first feature structure and the second feature structure from an imaging system. The calibration mark is formed on the wafer, and a calibration mark with a smaller size can be realized, which is beneficial to calibration for an imaging system with a larger magnification. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.
[0018] Figure 1 A schematic diagram of a calibration structure provided by an embodiment of the present application is shown;
[0019] Figure 2A structure diagram of a calibration mark provided by an embodiment of the present application is shown.
[0020] Figure 3 A top view of a calibration structure provided by an embodiment of the present application is shown.
[0021] Figure 4 A schematic diagram of a target area provided by an embodiment of the present application is shown. DETAILED DESCRIPTION
[0022] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application are described in detail below with reference to the accompanying drawings.
[0023] In the following description, a lot of specific details are set forth in order to facilitate a full understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.
[0024] Secondly, the present application is described in detail in combination with the schematic diagram, when the embodiments of the present application are described, for the convenience of description, the cross-sectional view of the device structure will be partially enlarged without the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.
[0025] In order to facilitate understanding, the calibration structure provided by an embodiment of the present application is described in detail below in combination with the accompanying drawings.
[0026] REFERENCE Figure 1 As shown, a schematic diagram of a calibration structure provided by an embodiment of the present application is shown, the calibration structure includes a wafer 100 and a calibration mark 110 on the wafer 100.
[0027] In the embodiments of the present application, the wafer 100 can be a semiconductor wafer, such as a silicon wafer or a germanium wafer, etc. The film layer on the wafer 100 can be prepared by a photolithography process, which is beneficial to improve the line width precision of the calibration mark 110 thereon, and the line width precision of the calibration mark is much higher than that of the ordinary calibration plate, so that the calibration of the imaging system with a larger magnification can be realized.
[0028] The calibration mark 110 has first feature structures 111 and second feature structures 112 arranged at intervals, the first feature structures 111 are first film layers on the wafer 100, and the second feature structures 112 are second film layers on the wafer 100; the reflectivities of the first feature structures 111 and the second feature structures 112 are different, so that the first feature structures 111 and the second feature structures 112 are in different colors. Thus, the first feature structures and the second feature structures can be distinguished from an imaging system, the calibration mark can be formed on the wafer, and a calibration mark with a smaller size can be realized, which is beneficial to calibration for an imaging system with a larger magnification.
[0029] Specifically, the contrast of the first feature structures 111 and the second feature structures 112 is greater than a preset value, for example, the reflectivity of the first feature structures 111 is relatively high, and the first feature structures 111 can be white, and the reflectivity of the second feature structures 112 is relatively low, and the second feature structures 112 can be close to black, so that the contrast of the first feature structures 111 and the second feature structures 112 is relatively large, and thus the first feature structures 111 and the second feature structures 112 are easy to identify. That is, the calibration mark 110 includes black regions and white regions arranged at intervals. The materials of the first feature structures 111 and the second feature structures 112 are different, so that the first feature structures 111 and the second feature structures 112 have different reflectivities.
[0030] The first feature structures 111 and the second feature structures 112 have flush upper surfaces, and the thicknesses of the first film layers and the second film layers are the same, so that the influence of aberration caused by the calibration structure itself can be reduced.
[0031] In the embodiment, the first feature structures 111 and the second feature structures 112 are periodically arranged in a first direction x and a second direction y; in one calibration mark 110, the number of the first feature structures 111 arranged in the first direction x is greater than or equal to 3, and the number of the first feature structures 111 arranged in the second direction y is greater than or equal to 3. The first direction and the second direction can be perpendicular or at a certain angle, so that the first feature structures 111 and the second feature structures 112 are distributed in a certain area to form the calibration mark 110. The number of the first feature structures 111 in the first direction can be the same as or different from the number of the first feature structures 111 in the second direction.
[0032] The shapes of the feature patterns of the first feature structures 111 and the second feature structures 112 are polygons, for example, triangles, quadrilaterals, hexagons, etc., and the shapes of the feature patterns of the first feature structures 111 and the second feature structures 112 can be the same or different. When the shapes of the feature patterns of the first feature structures 111 and the second feature structures 112 are the same, the feature sizes of the first feature structures 111 and the second feature structures 112 can be the same or different. Of course, each first feature structure 111 in the same calibration mark can have the same shape and size to simplify calculation.
[0033] The first direction x and the second direction y are perpendicular, and the shape of the feature pattern of at least one of the first feature structure 111 and the second feature structure 112 is a square, so that the size of the calibration mark can be determined according to the side length and the pitch of the square. As an example, the shape of the feature pattern of the first feature structure 111 and the second feature structure 112 can both be a square. As shown in FIG. 1, the shape of the feature pattern of the first feature structure 111 and the second feature structure 112 is a square, and the size of the calibration mark is 4 microns x 4 microns. Figure 2 As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here.
[0034] In actual operation, the size of the feature pattern of the first feature structure 111 and the second feature structure 112 is limited by the lithography support and also by the imaging system. The size of the feature pattern of the first feature structure 111 and the second feature structure 112 ranges from 0.8 microns to 5000 microns. Too small a size is easily affected by diffraction in the lithography process, affecting the accuracy, and is also easily affected by the magnification of the imaging system, making it impossible to distinguish.
[0035] As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here. Figure 2 As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here.
[0036] In the embodiment of the present application, the wafer 100 can include a plurality of calibration regions 1001, and each calibration region 1001 is provided with a calibration mark 110. As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here. Figure 3 As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here.
[0037] As shown in FIG. 1, the structure of the calibration mark provided in the embodiment of the present application is a top view of the calibration structure, and the two can have the same size to simplify the calculation. As another example, the shape of the feature pattern of the second feature structure 111 can be a square, and the shape of the feature pattern of the second feature structure 112 can be a rectangle, the length of the rectangle being equal to the side length of the square, and the width being less than the side length of the square, which is not shown here. Figure 4As shown, the target area is a schematic diagram of a target area provided by an embodiment of the present application. The sizes of the first feature structure 111 in the plurality of calibration marks 110 in the target area are different, and the plurality of calibration marks 110 correspond to imaging systems of different magnification ratios, so that the imaging systems of different magnification ratios can be calibrated by calibration marks 110 of different sizes, avoiding the problem that the size of the calibration mark 110 is too large to completely image the first feature structure 111 and the second feature structure 112, and avoiding the problem that the calibration mark 110 is too small to be distinguished.
[0038] The imaging systems of different magnification ratios include a first imaging system with a first magnification ratio and a second imaging system with a second magnification ratio. When the first magnification ratio is greater than the second magnification ratio, the feature pattern of the first feature structure 111 in the calibration mark 110 corresponding to the first imaging system is smaller than the feature pattern of the first feature structure 111 in the calibration mark 110 corresponding to the second imaging system.
[0039] As an example, the first magnification ratio is 100, the size of the feature pattern of the first feature structure 111 in the calibration mark 110 corresponding to the first imaging system is 200 microns, and the second magnification ratio is 20, the size of the feature pattern of the first feature structure 111 in the calibration mark 110 corresponding to the second imaging system is 1 millimeter. Taking the first feature structure 111 and the second feature structure 112 as squares with equal sizes as an example, the calibration mark 110 includes black and white checkerboards. The size of the checkerboard in the calibration mark 110 corresponding to the first magnification ratio of 100 is 200 microns x 200 microns, and the size of the checkerboard in the calibration mark 110 corresponding to the second magnification ratio of 20 is 1 millimeter x 1 millimeter.
[0040] Based on the above calibration structure, an embodiment of the present application further provides a calibration method, which can include the following steps.
[0041] S101, providing the calibration structure.
[0042] The calibration structure is described above and will not be described again.
[0043] S102, capturing the calibration structure by the imaging system to obtain a calibration image.
[0044] Specifically, the calibration structure can be placed in the field of view of the imaging system, and then focused and captured to obtain a calibration image. Alternatively, the calibration structure can be placed in the field of view of the imaging system, and then focused and focused. After focusing, the focusing surface is taken as a focal surface, and a sequence of images is collected from the out-of-focus position above the focal surface to the out-of-focus position below the focal surface, and the image with the best contrast is selected from the image sequence as the calibration image.
[0045] S103, calibrate the imaging system according to the actual size of the calibration mark in the calibration structure and the pixel size of the calibration mark in the calibration image.
[0046] In the process of calibrating the imaging system, the magnification of the imaging system can be calibrated, or the pixel size of a single pixel of the imaging system can be calibrated.
[0047] Specifically, the magnification of the imaging system can be calibrated according to the actual size of the calibration mark in the calibration structure and the pixel size of the calibration mark in the calibration image. Generally, the ratio of the pixel size to the actual size is the magnification.
[0048] Suppose 20 black and white grids in the first direction of the field of view are taken, and the grid size is 1 micrometer, then the object size is 20*1 micrometer=20 micrometers.
[0049] If the number of pixels corresponding to the 20 grids in the calibration image is 400, and the pixel size of a single pixel of the imaging system is 5 micrometers, then the image size on the image side is 400*5 micrometers=2000 micrometers, and the magnification of the imaging system is 2000 / 20=100 times, which is the ideal state for a 100X imaging system.
[0050] If the number of pixels corresponding to the 20 grids in the calibration image is 404, then the image size on the image side is 404*5 micrometers=2020 micrometers, and the corresponding magnification is 2020 / 20=101, which means that the magnification is not accurate for a 100X imaging system and needs to be adjusted.
[0051] Specifically, the actual magnification of the imaging system can be determined according to the actual size of the calibration mark in the calibration structure and the pixel size of the calibration mark in the calibration image; and the pixel size of a single pixel of the imaging system can be calibrated according to the actual magnification of the imaging system. The pixel size of a single pixel can be determined according to the ratio of the product of the actual magnification and the actual size to the pixel size.
[0052] Suppose 20 black and white grids in the first direction of the field of view are taken, and the grid size is 1 micrometer, then the object size is 20*1 micrometer=20 micrometers.
[0053] If the number of pixels corresponding to the 20 grids in the calibration image is 404, then the image size on the image side is 404*5 micrometers=2020 micrometers, and the corresponding magnification is 2020 / 20=101, which means that the magnification is not accurate for a 100X imaging system. In order to restore the object size, the size of a single pixel can be set to 20 micrometers*100 / 404=4.9505 micrometers at this time.
[0054] The embodiment of the present application provides a calibration structure, including a wafer and a calibration mark on the wafer, the calibration mark has first feature structures 111 and second feature structures 112 arranged at intervals, the first feature structures are first film layers on the wafer, the second feature structures are second film layers on the wafer, the reflectivity of the first feature structures and the second feature structures is different, so that the first feature structures and the second feature structures are different in color, so that the first feature structures and the second feature structures can be distinguished from an imaging system, the calibration mark is formed on the wafer, and a calibration mark with a smaller size can be realized, and calibration for an imaging system with a larger magnification is facilitated.
[0055] The above merely describes the preferred embodiments of the present application, and the above is disclosed as the preferred embodiments of the present application, but is not used to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application or modify equivalent embodiments with equivalent changes without departing from the scope of the technical solutions of the present application by using the disclosed methods and technical contents. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solutions of the present application still belongs to the protection scope of the technical solutions of the present application.
Claims
1. A calibration structure, characterized in that, The calibration structure includes a wafer and calibration marks on the wafer. The calibration marks have a first feature structure and a second feature structure arranged at intervals. The first feature structure is a first film layer on the wafer, and the second feature structure is a second film layer on the wafer. The first feature structure and the second feature structure have different reflectivities, causing the first feature structure and the second feature structure to appear as different colors.
2. The calibration structure according to claim 1, characterized in that, The first feature structure and the second feature structure have flush upper surfaces, and the first film layer and the second film layer have the same thickness.
3. The calibration structure according to claim 1, characterized in that, The wafer includes multiple calibration areas, and each calibration area is equipped with the calibration mark.
4. The calibration structure according to claim 3, characterized in that, The target area in the multiple calibration regions is provided with multiple calibration marks, and the first feature structure in the multiple calibration marks has a different size. The multiple calibration marks correspond to imaging systems with different magnifications.
5. The calibration structure according to claim 4, characterized in that, The imaging systems with different magnifications include a first imaging system with a first magnification and a second imaging system with a second magnification. When the first magnification is greater than the second magnification, the feature pattern of the first feature structure in the calibration mark corresponding to the first imaging system is smaller than the feature pattern of the first feature structure in the calibration mark corresponding to the second imaging system.
6. The calibration structure according to claim 5, characterized in that, The first magnification is 200 micrometers, and the second magnification is 20, where the size of the feature pattern of the first feature structure in the calibration mark corresponding to the first imaging system is 1 millimeter.
7. The calibration structure according to claim 1, characterized in that, The size range of the feature patterns of the first feature structure and the second feature structure is 0.8-5000 micrometers.
8. The calibration structure according to any one of claims 1-7, characterized in that, The first feature structure and the second feature structure are periodically arranged in the first direction x and the second direction y; in a calibration mark, the number of the first feature structure arranged in the first direction x is greater than or equal to 3, and the number of the first feature structure arranged in the second direction y is greater than or equal to 3.
9. The calibration structure according to claim 8, characterized in that, The shape of the feature patterns of the first feature structure and the second feature structure is a polygon.
10. The calibration structure according to claim 9, characterized in that, The first direction x and the second direction y are perpendicular, and the shape of the feature pattern of at least one of the first feature structure and the second feature structure is a square.
11. The calibration structure according to any one of claims 1-7, characterized in that, The contrast between the first feature structure and the second feature structure is greater than a preset value.