CN111583397B - Three-dimensional reconstruction method and device - Google Patents
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Abstract
The embodiment of the application provides a three-dimensional reconstruction method and a three-dimensional reconstruction device, which can scan a structure to be detected by using an electron beam scanning device to obtain an electron beam image, and can fit to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the model parameters can embody the three-dimensional characteristics of the structure to be detected, that is, the three-dimensional characteristics of the structure to be detected can be obtained by processing the electron beam image, so that the three-dimensional reconstruction of the structure to be detected can be performed by using the model parameters embodying the three-dimensional characteristics of the structure to be detected. The electron beam imaging model can fit electron beam images and depends on the corresponding relation between model parameters and image information, so that the electron beam imaging model is not influenced by edge angles, can be suitable for three-dimensional reconstruction of the structure to be detected at each edge angle, improves the accuracy of three-dimensional reconstruction of the structure to be detected at high edge angles, and further improves the accuracy of monitoring the process quality.
Description
Technical Field
The present application relates to the field of integrated circuits, and in particular, to a three-dimensional reconstruction method and apparatus.
Background
In the field of integrated circuits, the three-dimensional morphology of a device can embody the process quality and structural characteristics of the device, and how to obtain the three-dimensional morphology of the device is an important problem. At present, electron beam microscopy equipment can be utilized to scan a device structure to obtain electron beam imaging intensities at different positions, and then a three-dimensional reconstruction technology is utilized to analyze the electron beam imaging intensities to obtain the three-dimensional morphology of the device structure.
Generally speaking, the device structure may be divided into a continuous graded structure and a vertical edge structure, where in the continuous graded structure, the height of the surface changes slowly, so that the three-dimensional morphology of the device structure can be better reconstructed by using the functional relationship between the electron beam imaging intensity and the structure, and the vertical edge structure changes quickly at a certain position, at this time, the functional relationship between the electron beam imaging intensity and the structure is not accurate enough, so that the three-dimensional morphology of the device structure is difficult to obtain.
How to reconstruct the vertical edge structure in three dimensions is a problem to be solved in the art.
Disclosure of Invention
In order to solve the technical problems, the embodiment of the application provides a three-dimensional reconstruction method and a device, which expand the application range of the three-dimensional reconstruction technology and improve the accuracy of three-dimensional reconstruction.
The embodiment of the application provides a three-dimensional reconstruction method, which comprises the following steps:
acquiring an electron beam image, wherein the electron beam image is obtained by scanning a structure to be detected by using electron beam scanning equipment;
fitting to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model; the model parameters embody the three-dimensional characteristics of the structure to be tested;
and carrying out three-dimensional reconstruction of the structure to be detected by using the model parameters.
Optionally, the method further comprises: extracting the outline of the electron beam image to obtain at least one outline, and fitting the model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the method comprises the following steps:
And fitting to obtain model parameters corresponding to all lines based on gray distribution information on at least one line perpendicular to the contour line by using an electron beam imaging model, wherein the model parameters are used as the model parameters corresponding to the electron beam image.
Optionally, the electron beam image is subjected to contour extraction by using an edge contour algorithm, wherein the contour algorithm comprises at least one of the following algorithms: absolute threshold algorithm, relative threshold algorithm, frequency domain algorithm, correlation algorithm.
Optionally, the electron beam imaging model includes a first scattering model and a second scattering model, an edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, and an edge angle corresponding to the second scattering model is greater than the preset angle, and the fitting using the electron beam imaging model to obtain model parameters corresponding to the electron beam image includes:
and determining whether the edge angle corresponding to the electron beam image is larger than a preset angle, if so, fitting by using the second scattering model to obtain model parameters corresponding to the electron beam image, and if not, fitting by using the first scattering model to obtain the model parameters corresponding to the electron beam image.
Optionally, the model parameters include at least one of the following parameters: structure width, structure height, rising edge inclination, falling edge inclination, imaging attenuation length, rising edge coordinates, falling edge coordinates.
Optionally, fitting to obtain model parameters corresponding to the electron beam image by using a fitting algorithm, where the fitting algorithm includes one of the following fitting methods: parameter value traversal method, newton method, gradient descent method, conjugate gradient method, least square method, neural network method, and machine learning method.
Optionally, the structure to be tested includes: a raised line structure, a groove structure, or a hole pattern structure.
The embodiment of the application also provides a three-dimensional reconstruction device, which comprises:
The image acquisition unit is used for acquiring an electron beam image, wherein the electron beam image is obtained by scanning a structure to be detected by using electron beam scanning equipment;
the parameter acquisition unit is used for fitting to obtain model parameters corresponding to the electron beam image by utilizing an electron beam imaging model; the model parameters embody the three-dimensional characteristics of the structure to be tested;
And the reconstruction unit is used for carrying out three-dimensional reconstruction of the structure to be detected by utilizing the model parameters.
Optionally, the parameter obtaining unit includes:
The contour extraction unit is used for extracting the contour of the electron beam image to obtain at least one contour line;
And the parameter acquisition subunit is used for fitting to obtain model parameters corresponding to each line based on gray level distribution information on at least one line perpendicular to the contour line by using an electron beam imaging model, and the model parameters are used as the model parameters corresponding to the electron beam image.
Optionally, the electron beam image is subjected to contour extraction by using an edge contour algorithm, wherein the contour algorithm comprises at least one of the following algorithms: absolute threshold algorithm, relative threshold algorithm, frequency domain algorithm, correlation algorithm.
Optionally, the electron beam imaging model includes a first scattering model and a second scattering model, an edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, and an edge angle corresponding to the second scattering model is greater than the preset angle, and the parameter obtaining unit is specifically configured to:
and determining whether the edge angle corresponding to the electron beam image is larger than a preset angle, if so, fitting by using the second scattering model to obtain model parameters corresponding to the electron beam image, and if not, fitting by using the first scattering model to obtain the model parameters corresponding to the electron beam image.
Optionally, the model parameters include at least one of the following parameters: structure width, structure height, rising edge inclination, falling edge inclination, imaging attenuation length, rising edge coordinates, falling edge coordinates.
Optionally, fitting to obtain model parameters corresponding to the electron beam image by using a fitting algorithm, where the fitting algorithm includes one of the following fitting methods: parameter value traversal method, newton method, gradient descent method, conjugate gradient method, least square method, neural network method, and machine learning method.
Optionally, the structure to be tested includes: a raised line structure, a groove structure, or a hole pattern structure.
The embodiment of the application provides a three-dimensional reconstruction method and a three-dimensional reconstruction device, which can scan a structure to be detected by using an electron beam scanning device to obtain an electron beam image, and can fit to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the model parameters can embody the three-dimensional characteristics of the structure to be detected, that is, the three-dimensional characteristics of the structure to be detected can be obtained by processing the electron beam image, so that the three-dimensional reconstruction of the structure to be detected can be performed by using the model parameters embodying the three-dimensional characteristics of the structure to be detected. The electron beam imaging model can fit electron beam images and depends on the corresponding relation between model parameters and image information, so that the electron beam imaging model is not influenced by edge angles, can be suitable for three-dimensional reconstruction of the structure to be detected at each edge angle, improves the accuracy of three-dimensional reconstruction of the structure to be detected at high edge angles, and further improves the accuracy of monitoring the process quality.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to these drawings for those of ordinary skill in the art.
FIG. 1 is a flow chart of a three-dimensional reconstruction method according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a structure to be tested according to an embodiment of the present application;
FIG. 3 is a schematic diagram of an electron beam image according to an embodiment of the present application;
fig. 4 is a schematic diagram of gray scale distribution according to an embodiment of the present application;
Fig. 5 is a schematic diagram of fitting distribution information obtained by fitting according to an embodiment of the present application;
FIG. 6 is a schematic diagram of a reconstruction structure according to an embodiment of the present application;
Fig. 7 is a block diagram of a three-dimensional reconstruction device according to an embodiment of the present application.
Detailed Description
In order to make the present application better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the field of integrated circuits, the three-dimensional morphology of the device can be obtained by using a three-dimensional reconstruction technology, specifically, the device structure can be scanned by using electron beam microscopy equipment to obtain electron beam imaging intensities at different positions, and then the electron beam imaging intensities are analyzed by using the three-dimensional reconstruction technology to obtain the three-dimensional morphology of the device structure.
However, the current three-dimensional reconstruction method can reconstruct the three-dimensional morphology of the device structure by using the functional relationship between the electron beam imaging intensity and the structure, for example, the electron beam imaging intensity can be a derivative function of the surface height of the structure, thereby reconstructing the three-dimensional morphology of the device structure. However, the method can better reconstruct the three-dimensional morphology of the continuous slowly-varying structure, and for the vertical edge structure, the fault appears in the differential function between the structure surface height and the electron beam imaging intensity, and the determined three-dimensional morphology is not accurate enough, so the three-dimensional reconstruction method cannot accurately obtain the three-dimensional morphology of the device structure with larger height variation, such as the three-dimensional morphology of the vertical edge structure.
Based on the above technical problems, the embodiments of the present application provide a three-dimensional reconstruction method and apparatus, which may scan a structure to be measured with an electron beam scanning device to obtain an electron beam image, and may fit to obtain model parameters corresponding to the electron beam image with an electron beam imaging model, where the model parameters may represent three-dimensional characteristics of the structure to be measured, that is, may process the electron beam image to obtain three-dimensional characteristics of the structure to be measured, so that three-dimensional reconstruction of the structure to be measured may be performed with the model parameters that represent three-dimensional characteristics of the structure to be measured. The electron beam imaging model can fit electron beam images and depends on the corresponding relation between model parameters and image information, so that the electron beam imaging model is not influenced by edge angles, can be suitable for three-dimensional reconstruction of the structure to be detected at each edge angle, improves the accuracy of three-dimensional reconstruction of the structure to be detected at high edge angles, and further improves the accuracy of monitoring the process quality.
The following describes in detail, by way of embodiments, a specific implementation manner of a three-dimensional reconstruction method and apparatus in an embodiment of the present application with reference to the accompanying drawings.
Referring to fig. 1, a flowchart of a three-dimensional reconstruction method according to an embodiment of the present application may include the following steps:
S101, acquiring an electron beam image.
In the embodiment of the application, the structure to be detected can be scanned, the structure to be detected can be an independent structure in a device, the independent structure can be a regular structure such as a convex line structure, a groove structure or a hole structure, and the like, can also be other irregular structures which are convex or concave on a plane, and can also be a structure with severe height change or a structure with more gradual height change. Referring to fig. 2, a schematic diagram of a structure to be tested according to an embodiment of the present application is shown, wherein the structure to be tested is a bump line structure, and the bump line structure has a certain height and width.
Scanning of the structure to be measured can be performed by using an electron beam scanning device, such as a scanning electron microscope (Scanning Electron Microscope, SEM) or a transmission electron microscope (Transmission Electron Microscope, TEM), the electron beam scanning device can emit an electron beam to the structure to be measured, the electron beam interacts with the structure to be measured, and various physical information is excited, for example, electrons around the structure to be measured can be collected to form an electron beam image, and referring to fig. 3, a schematic diagram of the electron beam image is provided in an embodiment of the present application, and gray level distribution information in the electron beam image represents the number of electrons, so as to represent interaction between the structure to be measured and the electron beam.
The angle for scanning the structure to be detected by using the electron beam scanning equipment can be a single angle, for example, can be vertical overlooking scanning, so that the problem of difficult operation caused by three-dimensional reconstruction of a plurality of electron beam images obtained by combining a plurality of scanning angles in the prior art is avoided.
The electron beam image is obtained by scanning the structure to be detected, so that one structure to be detected corresponds to one electron beam image, the electron beam image represents the structural characteristics of the corresponding structure to be detected, for example, the structure to be detected is a convex line structure, and the corresponding electron beam image represents the structural characteristics of the convex line structure.
In actual operation, a device may include a plurality of independent structures, and each independent structure may be used as a structure to be tested, and these structures to be tested may be scanned to obtain an original image at the same time, and the original image may be divided to obtain a plurality of structure areas, where each structure area includes only one independent structure, and each structure area may be used as an electron beam image, so as to reflect the structural characteristics of the independent structure in the structure area. For example, the device comprises a plurality of two structures to be tested, namely a convex line structure and a concave groove structure, and an electron beam image showing the structural characteristics of the convex line structure and an electron beam image showing the structural characteristics of the concave groove structure can be obtained by scanning the two structures to be tested.
The electron beam image may represent structural characteristics of the structure to be measured, specifically, a contour in the electron beam image may represent contour characteristics of the structure to be measured, a distance between the contours may represent a size of the structure to be measured, and a gray scale distribution of the electron beam image may represent a height change of the structure to be measured. After the electron beam image is obtained, the size relationship between the structure to be measured and the electron beam image can be calibrated, and in general, the size relationship between the structure to be measured and the electron beam image is determined by parameters of the electron beam scanning device, so that the size in the electron beam image can be converted into the actual size of the structure to be measured.
S102, fitting to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model.
The gray level distribution information of the electron beam image shows the interaction between the structure to be tested and the electron beam, so that the three-dimensional characteristic of the structure to be tested can be shown, the model parameters corresponding to the electron beam image can be obtained by fitting an electron beam imaging model, and the model parameters corresponding to the electron beam image can show the three-dimensional characteristic of the structure to be tested, so that the three-dimensional characteristic of the structure to be tested is obtained by processing the electron beam image. The three-dimensional characteristic of the structure to be measured is obtained by utilizing the electron beam imaging model, the simple functional relation between the height of the structure to be measured and the electron beam imaging intensity is not relied on, and more factors are considered, so that the obtained three-dimensional characteristic of the structure to be measured is more accurate and can be applied to a wider range.
Wherein the model parameters of the electron beam imaging model may comprise at least one of the following parameters: structure width, structure height, rising edge inclination, falling edge inclination, imaging decay length, rising edge coordinates, falling edge coordinates, and the like. It will be appreciated that the model parameters herein correspond to individual structures, each individual structure corresponding to a set of model parameters representing the three-dimensional characteristics of the individual structure, and thus each electron beam image may correspond to a set of determined model parameters, which may include model parameters for one or more locations.
In the embodiment of the application, the electron beam imaging model can obtain the corresponding image by using the model parameters, so the model parameters corresponding to the electron beam image are obtained by fitting the electron beam imaging model, essentially, the model parameters are adjusted to enable the obtained image to be close to the electron beam imaging model, and if the obtained image is consistent with or has smaller phase difference with the electron beam imaging model, the model parameters at the moment can be used as the model parameters corresponding to the electron beam image, namely, the electron beam image can be obtained under the model parameters.
Specifically, the model parameters corresponding to the electron beam image can be obtained by fitting with a fitting algorithm, and the fitting algorithm can be one of the following fitting methods: parameter value traversal method, newton method, gradient descent method, conjugate gradient method, least square method, neural network method, machine learning method, etc.
In order to reduce the fitting calculation amount, features can be extracted from the electron beam image, so that fitting can be performed in a targeted manner. Specifically, the contour extraction can be performed on the electron beam image to obtain at least one contour line, then gray distribution information on at least one line perpendicular to the contour line can be extracted, and model parameters corresponding to the electron beam image can be obtained by fitting an electron beam imaging model based on the gray distribution information on the lines. This is because the gradation is not greatly different in the direction of parallel contour lines, and thus the gradation distribution information on at least one line perpendicular to the contour lines is extracted, and the data processing amount can be reduced while important information is extracted, thereby improving the three-dimensional reconstruction efficiency.
Specifically, the electron beam image may be subjected to contour extraction using an edge contour algorithm, which includes at least one of the following algorithms: absolute threshold algorithms, relative threshold algorithms, frequency domain algorithms, correlation algorithms, etc. After contour extraction is performed on the electron beam image, contour parameters may be obtained for representing contour characteristics, where the contour parameters may include contour distance, contour roughness, distance roughness, and the like.
In the embodiment of the present application, the profile extraction may be performed on the electron beam image by using a relative threshold algorithm, and referring to fig. 3, two of the profile lines are vertical profile lines, and referring to fig. 4, a gray distribution schematic diagram provided in the embodiment of the present application is provided, the dotted line direction is gray distribution information on one line in the horizontal direction in fig. 3, the abscissa is position (position), the ordinate is electron intensity (SE), and the unit is dimensionless (a.u.), and it can be seen that very high electron intensity appears in the profile lines, and the electron intensity rapidly changes at adjacent positions on both sides of the profile lines, and gradually decreases between the two profile lines.
In actual operation, noise may exist in the electron beam image, so that the obtained gray level distribution information has obvious noise, and therefore, the noise of the electron beam image can be removed by using a denoising algorithm, and the denoising mode can include one or more of a neighbor average effect method, a frequency domain denoising algorithm, a Gaussian denoising algorithm, a convolution denoising algorithm and the like, so that more accurate gray level distribution information can be obtained. The principle of denoising by using a denoising algorithm is that gray level distribution on a plurality of adjacent lines perpendicular to a contour line is averaged, so that differences among the lines caused by noise can be reduced, and the distance and the number of the adjacent lines can be determined according to actual conditions.
After the gray distribution information on the line perpendicular to the contour line is obtained, the electron beam imaging model may be used to obtain the model parameters corresponding to the electron beam image by fitting based on the gray distribution information on the line perpendicular to the contour line, and referring to fig. 4, the solid line is the fitting distribution information corresponding to the model parameters obtained by fitting the gray distribution information, and when the gray distribution information and the fitting distribution information have a small difference, the model parameters corresponding to the fitting distribution information may be used as the model parameters obtained by fitting.
Because the contour line has a certain length, gray level distribution information of a plurality of lines perpendicular to the contour line can be obtained at different positions of the contour line, and model parameters corresponding to each line are obtained, so that the model parameters corresponding to the plurality of lines are used as model parameters corresponding to the electron beam image.
Referring to fig. 5, a schematic diagram of fitting distribution information obtained by fitting according to an embodiment of the present application has a gray distribution similar to that of the electron beam image shown in fig. 3, and suppresses background random noise to a certain extent, thereby improving the accuracy of image recognition. The model parameters corresponding to the fitting distribution information can be used as model parameters corresponding to the electron beam image and used for reflecting the three-dimensional characteristics of the structure to be detected corresponding to the electron beam image.
In the embodiment of the application, the electron beam imaging model may be a secondary electron scattering model of the electron beam scanning device in an imaging process, and the electron beam imaging model may include a first scattering model and a second scattering model, where an edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, and an edge angle corresponding to the second scattering model is greater than the preset angle, and the preset angle range may be 60 ° to 90 °, for example, may be 70 °, so that, relative to the first scattering model, the second scattering model may consider a vertical edge effect to adapt to an actual imaging process with a larger edge angle.
Therefore, different electron beam imaging models can be used for different electron beam images, for example, whether the edge angle corresponding to the electron beam image is larger than a preset angle can be judged, if yes, model parameters corresponding to the electron beam image can be obtained by fitting the second scattering model, and if not, model parameters corresponding to the electron beam image can be obtained by fitting the first scattering model. The corresponding edge angle for e-beam imaging is the edge angle of the individual structures in the e-beam image.
S103, performing three-dimensional reconstruction of the structure to be detected by using model parameters corresponding to the electron beam image.
After obtaining the model parameters corresponding to the electron beam image, the model parameters can represent the three-dimensional characteristics of the structure to be measured, so that the model parameters can be utilized to reconstruct the three-dimensional structure to be measured, and referring to fig. 6, a schematic diagram of the reconstructed structure provided by the embodiment of the application can represent the Height (Height), width, edge angle and other characteristics of the structure to be measured, wherein the unused positions in the plane perpendicular to the Height are represented by coordinates (position), and the units are all nm. Comparing the reconstruction structure of fig. 6 with the structure to be measured of fig. 2, it can be known that the reconstruction structure and the structure to be measured have higher similarity, so that the reconstruction effect is good, the precision is high, the robustness is good, and meanwhile, the reconstruction structure has obvious inhibition effect on some background noise.
In the embodiment of the application, the three-dimensional reconstruction structure can be analyzed and evaluated, the analysis result is utilized to adjust the electron beam imaging model, or the edge contour algorithm is reselected, or the fitting method is reselected, or the denoising method is reselected, so that the optimization of the three-dimensional reconstruction method is realized, and the accuracy of the three-dimensional reconstruction is improved.
The embodiment of the application provides a three-dimensional reconstruction method, which can scan a structure to be detected by using electron beam scanning equipment to obtain an electron beam image, and can fit to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the model parameters can embody the three-dimensional characteristics of the structure to be detected, that is, the three-dimensional characteristics of the structure to be detected can be obtained by processing the electron beam image, so that the three-dimensional reconstruction of the structure to be detected can be performed by using the model parameters embodying the three-dimensional characteristics of the structure to be detected. The electron beam imaging model can fit electron beam images and depends on the corresponding relation between model parameters and image information, so that the electron beam imaging model is not influenced by edge angles, can be suitable for three-dimensional reconstruction of the structure to be detected at each edge angle, improves the accuracy of three-dimensional reconstruction of the structure to be detected at high edge angles, and further improves the accuracy of monitoring the process quality.
Based on the above three-dimensional reconstruction method, the embodiment of the present application further provides a three-dimensional reconstruction device, and referring to fig. 7, a structural block diagram of the three-dimensional reconstruction device provided by the embodiment of the present application is shown, where the device may include:
An image acquisition unit 110, configured to acquire an electron beam image, where the electron beam image is obtained by scanning a structure to be measured with an electron beam scanning device;
A parameter obtaining unit 120, configured to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model through fitting; the model parameters embody the three-dimensional characteristics of the structure to be tested;
and the reconstruction unit 130 is used for performing three-dimensional reconstruction of the structure to be detected by using the model parameters.
Optionally, the parameter obtaining unit includes:
The contour extraction unit is used for extracting the contour of the electron beam image to obtain at least one contour line;
And the parameter acquisition subunit is used for fitting to obtain model parameters corresponding to each line based on gray level distribution information on at least one line perpendicular to the contour line by using an electron beam imaging model, and the model parameters are used as the model parameters corresponding to the electron beam image.
Optionally, the electron beam image is subjected to contour extraction by using an edge contour algorithm, wherein the contour algorithm comprises at least one of the following algorithms: absolute threshold algorithm, relative threshold algorithm, frequency domain algorithm, correlation algorithm.
Optionally, the electron beam imaging model includes a first scattering model and a second scattering model, an edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, and an edge angle corresponding to the second scattering model is greater than the preset angle, and the parameter obtaining unit is specifically configured to:
and determining whether the edge angle corresponding to the electron beam image is larger than a preset angle, if so, fitting by using the second scattering model to obtain model parameters corresponding to the electron beam image, and if not, fitting by using the first scattering model to obtain the model parameters corresponding to the electron beam image.
Optionally, the model parameters include at least one of the following parameters: structure width, structure height, rising edge inclination, falling edge inclination, imaging attenuation length, rising edge coordinates, falling edge coordinates.
Optionally, fitting to obtain model parameters corresponding to the electron beam image by using a fitting algorithm, where the fitting algorithm includes one of the following fitting methods: parameter value traversal method, newton method, gradient descent method, conjugate gradient method, least square method, neural network method, and machine learning method.
Optionally, the structure to be tested includes: a raised line structure, a groove structure, or a hole pattern structure.
The embodiment of the application provides a three-dimensional reconstruction device, which can scan a structure to be detected by using electron beam scanning equipment to obtain an electron beam image, and can fit to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the model parameters can embody the three-dimensional characteristics of the structure to be detected, that is, the three-dimensional characteristics of the structure to be detected can be obtained by processing the electron beam image, so that the three-dimensional reconstruction of the structure to be detected can be performed by using the model parameters embodying the three-dimensional characteristics of the structure to be detected. The electron beam imaging model can fit electron beam images and depends on the corresponding relation between model parameters and image information, so that the electron beam imaging model is not influenced by edge angles, can be suitable for three-dimensional reconstruction of the structure to be detected at each edge angle, improves the accuracy of three-dimensional reconstruction of the structure to be detected at high edge angles, and further improves the accuracy of monitoring the process quality.
The "first" in the names of "first … …", "first … …", etc. in the embodiments of the present application are used for name identification, and do not represent the first in sequence. The rule applies equally to "second" etc.
From the above description of embodiments, it will be apparent to those skilled in the art that all or part of the steps of the above described example methods may be implemented in software plus general hardware platforms. Based on such understanding, the technical solution of the present application may be embodied in the form of a software product, which may be stored in a storage medium, such as a read-only memory (ROM)/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network communication device such as a router) to perform the method according to the embodiments or some parts of the embodiments of the present application.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments for relevant points. The above-described apparatus and system embodiments are merely illustrative, in which the modules illustrated as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed across multiple network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
The foregoing is merely a preferred embodiment of the present application and is not intended to limit the scope of the present application. It should be noted that modifications and adaptations to the present application may occur to one skilled in the art without departing from its scope.
Claims (5)
1. A method of three-dimensional reconstruction, the method comprising:
acquiring an electron beam image, wherein the electron beam image is obtained by scanning a structure to be detected by using electron beam scanning equipment;
Fitting to obtain model parameters corresponding to the electron beam image by using an electron beam imaging model; the model parameters embody the three-dimensional characteristics of the structure to be tested; the model parameters include at least one of the following: structure width, structure height, rising edge inclination, falling edge inclination, imaging attenuation length, rising edge coordinates, falling edge coordinates;
Carrying out three-dimensional reconstruction of the structure to be detected by utilizing the model parameters;
Extracting the outline of the electron beam image to obtain at least one outline, and fitting the model parameters corresponding to the electron beam image by using an electron beam imaging model, wherein the method comprises the following steps:
Fitting to obtain model parameters corresponding to all lines based on gray distribution information on at least one line perpendicular to the contour line by using an electron beam imaging model, wherein the model parameters are used as model parameters corresponding to the electron beam image;
Or, the electron beam imaging model includes a first scattering model and a second scattering model, an edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, and an edge angle corresponding to the second scattering model is larger than the preset angle, and the fitting using the electron beam imaging model to obtain model parameters corresponding to the electron beam image includes:
and determining whether the edge angle corresponding to the electron beam image is larger than a preset angle, if so, fitting by using the second scattering model to obtain model parameters corresponding to the electron beam image, and if not, fitting by using the first scattering model to obtain the model parameters corresponding to the electron beam image.
2. The method of claim 1, wherein the electron beam image is contour extracted using an edge contour algorithm, the contour algorithm comprising at least one of the following algorithms: absolute threshold algorithm, relative threshold algorithm, frequency domain algorithm, correlation algorithm.
3. The method according to any one of claims 1-2, wherein the model parameters corresponding to the electron beam image are obtained by fitting using a fitting algorithm, the fitting algorithm comprising one of the following fitting methods: parameter value traversal method, newton method, gradient descent method, conjugate gradient method, least square method, neural network method, and machine learning method.
4. The method according to any one of claims 1-2, wherein the structure to be measured comprises: a raised line structure, a groove structure, or a hole pattern structure.
5. A three-dimensional reconstruction apparatus, the apparatus comprising:
The image acquisition unit is used for acquiring an electron beam image, wherein the electron beam image is obtained by scanning a structure to be detected by using electron beam scanning equipment;
The parameter acquisition unit is used for fitting to obtain model parameters corresponding to the electron beam image by utilizing an electron beam imaging model; the model parameters embody the three-dimensional characteristics of the structure to be tested; the model parameters include at least one of the following: structure width, structure height, rising edge inclination, falling edge inclination, imaging attenuation length, rising edge coordinates, falling edge coordinates;
the reconstruction unit is used for carrying out three-dimensional reconstruction of the structure to be detected by utilizing the model parameters;
The parameter acquisition unit includes:
The contour extraction unit is used for extracting the contour of the electron beam image to obtain at least one contour line;
The parameter acquisition subunit is used for fitting to obtain model parameters corresponding to each line based on gray level distribution information on at least one line perpendicular to the contour line by using an electron beam imaging model, and the model parameters are used as model parameters corresponding to the electron beam image;
Or alternatively, the first and second heat exchangers may be,
The electron beam imaging model comprises a first scattering model and a second scattering model, the edge angle corresponding to the first scattering model is smaller than or equal to a preset angle, the edge angle corresponding to the second scattering model is larger than the preset angle, and the parameter obtaining unit is specifically configured to:
and determining whether the edge angle corresponding to the electron beam image is larger than a preset angle, if so, fitting by using the second scattering model to obtain model parameters corresponding to the electron beam image, and if not, fitting by using the first scattering model to obtain the model parameters corresponding to the electron beam image.
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