Method for correcting FOV image alignment error

Abstract

The present invention provides a method for correcting the alignment error of FOV images. An FOV image and its corresponding layout design file are obtained. The FOV image includes a plurality of irregular graphics. Align the irregular graphics in the middle part of the FOV image with the layout design file. Divide the FOV image into a plurality of partial images according to each irregular graphic. Align each partial image with the layout design file. The present invention performs alignment on local scanning electron microscope images, reducing the alignment error caused by image shooting.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for correcting the alignment error of FOV images. Background Art

[0002] The field of view (FOV) refers to the range that a lens can cover. (Objects beyond this angle will not be captured by the lens.) The range of scenery that a camera lens can cover is usually expressed in terms of an angle, and this angle is called the FOV of the lens. The area included in the visible image formed by the object through the lens on the focal plane is the field of view of the lens.

[0003] For SEM (scanning electron microscope) images with a large FOV, such as Figure 1 the shown image, the typical SEM image size can reach 4096×4096 pixels. For the contour extraction or CD (critical dimension) measurement of such large FOV images, after aligning the center of the image with the layout design file (GDS), the edge images will have alignment errors between the image and the layout design file due to factors such as image capture.

[0004] To solve the above problems, a new method for correcting the alignment error of FOV images is needed. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for correcting the alignment error of FOV images, which is used to solve the problem that for SEM images with a large FOV in the prior art, after aligning the center of the image with the layout design file, the edge images will have alignment errors between the image and the layout design file due to factors such as image capture.

[0006] To achieve the above purpose and other related purposes, the present invention provides a method for correcting the alignment error of FOV images, including:

[0007] Step 1: Obtain the FOV image and its corresponding layout design file, where the FOV image includes a plurality of irregular figures;

[0008] Step 2: Align the irregular figures in the middle part of the FOV image with the layout design file;

[0009] Step 3: Divide the FOV image into a plurality of local images according to each irregular figure;

[0010] Step 4: Align each local image with the layout design file.

[0011] Preferably, in Step 1, the FOV image is obtained by using a scanning electron microscope.

[0012] Preferably, in step two, the contour line of the irregular figure in the middle part of the FOV image is aligned with the layout design file.

[0013] Preferably, the contour line in step two is a closed figure.

[0014] Preferably, in step two, the key dimensions of the irregular figure in the middle part of the FOV image are measured and aligned with the layout design file.

[0015] Preferably, in step three, the FOV image is segmented into multiple local images according to the contour lines of each irregular figure with a set value added.

[0016] Preferably, the set value in step three is 25 nanometers.

[0017] Preferably, the irregular figure in the middle part of the FOV image and the layout design file in step two are aligned using the same reference system.

[0018] Preferably, each local image and the layout design file in step four are aligned using the same reference system.

[0019] As described above, the method for correcting the alignment error of the FOV image of the present invention has the following beneficial effects:

[0020] The present invention performs alignment on local scanning electron microscope images, reducing the alignment error caused by image capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram showing the alignment of the FOV image of the prior art;

[0022] Figure 2 Enlarged schematic diagram showing the alignment at point A of the FOV image of the prior art;

[0023] Figure 3 Enlarged schematic diagram showing the alignment at point B of the FOV image of the prior art;

[0024] Figure 4 Schematic diagram showing the design standard of the cutting image of the present invention;

[0025] Figure 5 First cutting image schematic diagram of the present invention;

[0026] Figure 6 Second cutting image schematic diagram of the present invention;

[0027] Figure 7 Third cutting image schematic diagram of the present invention;

[0028] Figure 8 It is shown as a schematic diagram of the method of the present invention. Detailed implementation manners

[0029] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] Please refer to Figure 8 , the present invention provides a method for correcting the alignment error of FOV images, including:

[0031] Step 1, obtain the FOV image and its corresponding layout design file. The FOV image includes multiple irregular graphics, a scanning electron microscope image of a large FOV. After aligning the image with the layout design file (GDS), the edge image will have an alignment error between the image and the layout design file due to factors such as image shooting.

[0032] In an embodiment of the present invention, in Step 1, a scanning electron microscope is used to obtain the FOV image. A scanning electron microscope (SEM) is an observation means between a transmission electron microscope and an optical microscope. It uses a very narrow and high-energy electron beam focused to scan the sample, and through the interaction between the electron beam and the substance, various physical information is excited. These information are collected, amplified, and re-imaged to achieve the purpose of characterizing the microscopic morphology of the substance. The resolution of a new type of scanning electron microscope can reach 1 nm; the magnification can be continuously adjusted up to 300,000 times and above; and it has a large depth of field, a large field of view, and a good three-dimensional imaging effect. It should be noted that the FOV image is preferably obtained by a scanning electron microscope, and can also be obtained by other types of microscopes.

[0033] Exemplarily, please refer to Figure 1 , the present invention provides a scanning electron microscope image of the EP5 model of ASML company. Please refer to Figure 2 , Figure 2 , the image at Figure 3 is the image of the middle part of the scanning electron microscope image, and there is no alignment error between the image here and the layout design file; please refer to Figure 3 , the image at

[0034] Step 2: Align the irregular figure in the middle part of the FOV image with the layout design file. Image alignment is one of the basic problems in the field of computer vision, that is, through pattern recognition, the irregular figure in the middle part of the FOV image can be aligned with the layout design file;

[0035] In an embodiment of the present invention, in Step 2, the contour line of the irregular figure in the middle part of the FOV image is extracted and aligned with the layout design file, that is, the contour line of the irregular figure is obtained by using graphics processing technology, and then aligned with the layout design file according to the contour line.

[0036] In an embodiment of the present invention, the contour line in Step 2 is a closed figure.

[0037] In an embodiment of the present invention, in Step 2, the critical dimensions of the irregular figure in the middle part of the FOV image are measured and aligned with the layout design file, that is, the line width of the irregular figure is measured and aligned with the layout design file.

[0038] In an embodiment of the present invention, in Step 2, the irregular figure in the middle part of the FOV image and the layout design file share the same reference system. Since the FOV image is obtained by photographing the device made from the layout design file, it is necessary to align the FOV image with the design figure in the layout design file to identify the error between the two. However, the edge image will cause an alignment error between the image and the layout design file due to factors such as image shooting. Therefore, the alignment in this step is a rough alignment, and the purpose is to establish a reference system adapted to the FOV image and the layout design file, that is, the coordinates of each irregular figure in the FOV image correspond one by one to the layout design file.

[0039] Step 3: Segment the FOV image into multiple local images according to each irregular figure. By segmenting the FOV image and then aligning it with the layout design file, the alignment error between the image and the layout design file caused by factors such as image shooting at the edge can be improved;

[0040] In an embodiment of the present invention, please refer to Figure 4 , in Step 3, the FOV image is segmented into multiple local images by increasing a set value according to the contour line of each irregular figure. That is to say, the closest distance from the edge of the local image to the contour line is the set value.

[0041] In an embodiment of the present invention, the set value in Step 3 is 25 nanometers, and local images such as Figures 5 to 7 are obtained. It should be understood that the set value here is determined according to the density of the figure, and other set values can also be used.

[0042] In an embodiment of the present invention, in Step 4, each local image and the layout design file share the same reference system.

[0043] Step 4: Align each partial image with the layout design file.

[0044] In an embodiment of the present invention, when aligning each partial image with the layout design file in Step 4, the same reference system is shared. By aligning each partial image with the layout design file, the alignment error caused by image shooting is reduced.

[0045] It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in actual implementation may be arbitrarily changed, and the layout type of its components may also be more complex.

[0046] In summary, the present invention performs alignment on the local scanning electron microscope image to reduce the alignment error caused by image shooting. Therefore, the present invention effectively overcomes various drawbacks in the prior art and has high industrial utilization value.

[0047] The above embodiments are only used to illustrate the principle and efficacy of the present invention by way of example, rather than to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for correcting the alignment error of FOV images, characterized in that, At least including: Step 1: Obtain a FOV image and its corresponding layout design file, where the FOV image includes a plurality of irregular figures; Step 2: Align the irregular figures in the middle part of the FOV image with the layout design file, and the irregular figures in the middle part of the FOV image and the layout design file share the same reference system for alignment; Step 3: Divide the FOV image into a plurality of local images according to each of the irregular figures; Step 4: Align each of the local images with the layout design file, and each of the local images and the layout design file share the same reference system for alignment.

2. The method for correcting the FOV image alignment error according to claim 1, wherein: In Step 1, the FOV image is obtained by using a scanning electron microscope.

3. The method for correcting the FOV image alignment error according to claim 1, characterized in that: In Step 2, alignment is achieved by extracting the contour lines of the irregular figures in the middle part of the FOV image with the layout design file.

4. The method for correcting the FOV image alignment error according to claim 1, wherein: In Step 2, alignment is achieved by measuring the critical dimensions of the irregular figures in the middle part of the FOV image with the layout design file.

5. The method for correcting the FOV image alignment error according to claim 1, characterized in that: In Step 3, the FOV image is divided into a plurality of local images according to the contour lines of each of the irregular figures by adding a set value.

6. The method for correcting the FOV image alignment error according to claim 5, characterized in that: The set value in Step 3 is 25 nanometers.

7. The method for correcting the FOV image alignment error according to claim 1, wherein: In Step 2, the irregular figures in the middle part of the FOV image and the layout design file share the same reference system for alignment.

8. The method for correcting the FOV image alignment error according to claim 7, characterized in that: In Step 4, each of the local images and the layout design file share the same reference system for alignment.

9. The method for correcting the FOV image alignment error according to claim 3, characterized in that: The contour line in Step 2 is a closed figure.

Images