Size measurement method, device and equipment based on through-focus scanning image and medium

Abstract

The invention discloses a size measurement method, device and equipment based on a through-focus scanning image and a medium, and relates to the technical field of nanometer device measurement. The method comprises the following steps: determining a size value set according to the prior morphology size of a to-be-measured nano device; establishing a simulation focus-through scanning image of each size in the size value set; performing principal component decomposition on the simulation focus-through scanning image to obtain a principal component coefficient matrix; establishing a regression matrix according to the size value set and the principal component coefficient matrix; performing principal component decomposition on the actually-measured focus-through scanning image of the to-be-measured nano device to obtain an actually-measured principal component coefficient matrix; and performing reverse inversion on the actually measured principal component coefficient matrix according to the regression matrix to obtain a measurement result. According to the method, the problem of out-of-focus image noise interference is effectively solved, the technical performance of the TSOM method is remarkably optimized in the aspects of precision, robustness, efficiency and the like, and key support is provided for large-scale application of the TSOM method in advanced nanometer manufacturing.

Description

Technical Field

[0001] The present invention relates to the field of nano-device measurement technology, and in particular to a dimension measurement method, device, equipment and medium based on through-focus scanning images. Background Art

[0002] The morphology and dimensions of nanodevices have a significant impact on device performance. For example, the fin width and height of a FinFET affect the channel effect and drive current, while the oxide thickness affects leakage current. To ensure product yield in nanofabrication and enable process control and iteration, precise measurement of key nanodevice morphology and dimensions is essential.

[0003] The through-focus scanning optical microscope (TSOM) measurement method establishes a regression model between grayscale representations and topographic dimensions in the through-focus scanning image, and then extracts the measurement results through inverse inversion. A through-focus scanning image is a stack of defocused images of the device under test, acquired with a metallographic microscope at varying degrees of defocus. Compared to in-focus images, defocused images can bypass the optical diffraction limit. TSOM also offers the advantages of low cost, ease of use, and non-destructiveness, making it a recommended measurement method in the integrated circuit industry.

[0004] As nanofabrication process nodes continue to decrease, the dimensions of key nanodevice features are also shrinking significantly, posing a significant challenge to the measurement accuracy of TSOM. Because defocused images captured by metallographic microscopes are highly susceptible to camera grayscale noise, regression models based on grayscale characterizations suffer from significant errors, making it difficult to control measurement errors below 5nm. This, in turn, hinders the application of TSOM methods in the nanofabrication industry.

[0005] Therefore, improving and optimizing TSOM to reduce the interference of camera grayscale noise on defocused images is particularly important for the promotion and application of TSOM in nanomanufacturing. Summary of the Invention

[0006] The present invention provides a through-focus scanning image-based dimension measurement method, device, equipment and medium to solve the problem that defocused images collected by a metallographic microscope are interfered with by camera grayscale noise, resulting in increased measurement errors and limiting the application of the TSOM method in advanced nanomanufacturing.

[0007] The present invention is achieved through the following technical solutions:

[0008] A first aspect of the present invention provides a nanometer size measurement method based on a through-focus scanning image, comprising:

[0009] Determine a size value set according to the prior morphological size of the nanodevice to be measured;

[0010] Creating a simulated through-focus scanning image for each size in the size value set;

[0011] performing principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix;

[0012] Establishing a regression matrix based on the size value set and the principal component coefficient matrix;

[0013] performing principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured to obtain a measured principal component coefficient matrix;

[0014] The measured principal component coefficients are reversely inverted according to the regression matrix to obtain measurement results.

[0015] Since the characteristic distribution of the through-focus scanning image comes from the spatial scattering field formed by the incident light modulated by the device morphology, it is closely related to the device morphology. Therefore, in order to solve the problem that the camera grayscale noise introduces errors and reduces the measurement accuracy, the present invention performs principal component analysis on the collected through-focus scanning image, characterizes the image feature distribution through the principal components of the image, effectively separates the noise and signal components, and suppresses the interference of random noise by retaining the main eigenvectors. A regression model of image features and measured key morphological dimensions is established through the principal components, which effectively improves the robustness of the regression model to grayscale noise. The present invention effectively solves the problem of noise interference in defocused images, significantly optimizes the technical performance of the TSOM method in terms of robustness and accuracy, and provides key support for its large-scale application in advanced nanomanufacturing.

[0016] In one embodiment, establishing a simulated through-focus scan image for each size in the size value set includes:

[0017] The size p j Input the microscopic imaging simulation model and obtain the size p j Defocused image sequence of nanodevices;

[0018] The defocused image sequence is stacked into a three-dimensional image block according to the defocused acquisition order, and a cross section of the three-dimensional image block is obtained with a size of p. j Simulated through-focus scanning image of the nanodevice.

[0019] In one embodiment, the microscopic imaging simulation model is represented as:

[0020]

[0021] Where “…” indicates an omitted integral sign. It represents the scattered near field formed by the plane wave component obtained by decomposing the Kohler illumination field and incident on the device surface. (x0, y0) is the object plane coordinate, (x, y) is the image plane coordinate, θ, They represent the x-component and y-component of the direction cosine angle of the plane wave component, (f x ,f y ) represents the spatial frequency corresponding to (x,y), H(f x ,f y ) represents the generalized pupil function including the defocus phase factor, which is expressed as:

[0022]

[0023] Where z represents the defocus amount and CNA represents the imaging numerical aperture.

[0024] In one embodiment, principal component decomposition is performed on the simulated through-focus scan image to obtain a principal component coefficient matrix, including:

[0025] Connect all the row vectors of the simulated through-focus scanning image head to tail and transpose them to get the column vector A j ;

[0026] The column vector A of all simulated through-focus scan images j Composition feature matrix A=[A1,A2,…,A j ,……A N ], where A j Corresponding to size p j The simulated through-focus scanning image of the nanodevice, N is the size value set {p j}The number of size values ​​in ;

[0027] Perform principal component decomposition on the feature matrix A to obtain the principal component matrix and the principal component coefficient matrix.

[0028] In one embodiment, a regression matrix is ​​established based on the size values ​​and the principal component coefficient matrix, including:

[0029] For the principal component coefficient matrix and size value set {p j} Perform multiple linear regression operation and obtain the set of size values ​​{p j} to the principal component coefficient matrix, expressed as:

[0030] RM=regress(PCC,{p j})

[0031] Where RM represents the regression matrix, regress(·) is the multiple linear regression function, PCC represents the principal component coefficient matrix, {p j} is a set of size values.

[0032] In one embodiment, the measured through-focus scanning image is acquired by a metallographic microscope in bright field mode, and the acquisition method includes:

[0033] Place the nanodevice to be tested on the microscope stage and adjust it to the focusing distance Z0 of the metallographic microscope;

[0034] Collecting the actual defocused image of the nanodevice to be tested at fixed step lengths within the range of [Z0-Z, Z0+Z];

[0035] The actual defocused images are stacked into three-dimensional image blocks according to the defocused acquisition sequence, and a cross section of the three-dimensional image block is taken to obtain a measured through-focus scanning image.

[0036] In one embodiment, performing inverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain the measurement result includes: performing inverse inversion using a least squares method to obtain the measurement result.

[0037] A second aspect of the present invention provides a nanometer size measurement device based on through-focus scanning images, comprising:

[0038] A priori value module, used to determine a size value set based on the priori shape and size of the nanodevice to be measured;

[0039] A simulation modeling module, configured to establish a simulated through-focus scanning image of each dimension value in the dimension value set;

[0040] a principal component extraction module, configured to perform principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix;

[0041] A regression modeling module, configured to establish a regression matrix based on the size value set and the principal component coefficient matrix;

[0042] The principal component extraction module is further configured to perform principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured, to obtain a measured principal component coefficient matrix;

[0043] The inverse inversion module is used to perform inverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain a measurement result.

[0044] According to a third aspect of the present invention, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the nano-size measurement method based on through-focus scanning images according to any one of the embodiments of the first aspect of the present invention is implemented.

[0045] According to a third aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the nanometer size measurement method based on through-focus scanning images according to any one embodiment of the first aspect of the present invention is implemented.

[0046] Compared with the existing technology, the present invention has the following advantages and beneficial effects: the introduction of principal component analysis in the TSOM method establishes a bridge from the distribution of principal component features of the image to the measured shape size. Compared with traditional methods, it reduces the interference of grayscale noise on the measurement results and effectively improves the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0048] Figure 1 is a flow chart of a nanometer size measurement method based on through-focus scanning images according to an embodiment of the present invention;

[0049] Figure 2 1 is a schematic diagram of the relationship between a defocused image sequence and a through-focus scan image according to an embodiment of the present invention;

[0050] Figure 3 It is a schematic diagram of a nanocylindrical structure;

[0051] Figure 4 1 is a schematic diagram of a principal component decomposition result according to an embodiment of the present invention;

[0052] Figure 5 This is a comparison chart of measurement errors using the method of the present invention and the traditional method. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0054] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to other steps or units inherent in the device.

[0055] The terms used in various embodiments of the present invention are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as those of ordinary skill in the art generally understood by the various embodiments of the present invention. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having idealized meaning or too formal meaning, unless clearly defined in various embodiments of the present invention.

[0056] The current general measurement method based on through-focus scan images is to convert the through-focus scan image into a grayscale representation, establish a regression model with the size based on the grayscale representation, and then perform inverse inversion by measuring the through-focus scan image to obtain the measured size. The grayscale representation is calculated using the following formula (1).

[0057] OIR=max{max{i}}-min{min{i}} (1)

[0058] Where i represents the through-focus scan image, and OIR represents the grayscale representation.

[0059] Since the defocused images collected by the metallographic microscope are easily affected by the grayscale noise of the camera, the regression model based on the grayscale characterization quantity OIR value has large errors, making it difficult to control the measurement error below 5nm. Therefore, the application of this method in the nanomanufacturing industry is severely limited.

[0060] In view of this, the present invention proposes a nanometer size measurement method based on through-focus scanning images, see Figure 1 The measurement method flow chart shown includes the following steps.

[0061] S1, determining a set of size values ​​according to the prior morphological dimensions of the nanodevice to be measured;

[0062] S2, creating a simulated through-focus scanning image of each size in the size value set;

[0063] S3, performing principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix;

[0064] S4, establishing a regression matrix based on the size value set and the principal component coefficient matrix;

[0065] S5, performing principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured, and obtaining a measured principal component coefficient matrix;

[0066] S6, performing reverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain the measurement results.

[0067] In step S1, for the key morphological dimensions of the nanodevice to be measured, the possible value range [p1, p2] is determined according to the prior value of the key morphological dimensions, and the values ​​are taken at equal intervals with a fixed interval △p within the range to form a dimension value set {p j}.

[0068] For each dimension, take value p j Simulations are performed to obtain simulated through-focus scan images corresponding to different sizes. A through-focus scan image is obtained by performing a through-focus scan of the device under test using a metallurgical microscope, obtaining a series of defocused images at different defocus levels. The defocused images are then stacked in the order of the focus scans to form a 3D image block. Finally, an XZ cross-section of the 3D image block is taken to obtain a 2D cross-section image. The X and Y axes correspond to the X and Y axes of the defocused image, and the Z axis corresponds to the optical axis.

[0069] The characteristic distribution of through-focus scan images originates from the spatial scattering field formed by incident light modulated by the device topography. This field is closely related to the device topography but is susceptible to camera grayscale noise. In this paper, the distribution of image features is characterized by the image's principal components, replacing traditional grayscale representations. This principal component-based regression model is then used to establish a correlation between image features and the dimensions of the key measured features, thereby reducing the impact of grayscale noise and effectively improving the regression model's robustness against grayscale noise.

[0070] In step S2, a numerical simulation method based on vector optical diffraction is used to establish simulated through-focus scanning images of various sizes, such as combining commonly used software Lumerical and Comsol in industrial applications with custom scripts to achieve efficient simulation.

[0071] In one embodiment of the present invention, a microscopic imaging simulation model is established by using the principle of vector optical diffraction. j Input the microscopic imaging simulation model and obtain the size p j The defocused image sequence of the nanodevice is then stacked into a three-dimensional image block according to the defocused acquisition order to obtain a size of p j Simulated through-focus scanning image of the nanodevice.

[0072] See also Figure 2The diagram below shows the relationship between the defocused image sequence and the through-focus scan image. The defocused image sequence is obtained within the upper and lower ranges [Z0-Z, Z0+Z] of the focus distance Z0, with each defocused image being captured at intervals of ΔZ, starting from the lower or upper limit. The defocused image sequence is stacked in the order of acquisition, forming a 3D image block. The simulated through-focus scan image is obtained by taking the XZ cross-section of the 3D image block.

[0073] by Figure 3 Taking the nano-cylinder structure shown in the figure as an example, the cylinder is made of gold and the base material is silicon. The measured morphological parameter is the diameter D of the cylinder. D = 153nm was previously measured by scanning electron microscopy and this value is used as the true value for verifying the measurement accuracy of the present invention. The height H = 100nm of the cylinder is used as a known quantity. Based on the prior value of the diameter D, the range of values ​​is selected as [140nm, 160nm]. Within this range, the values ​​are equally spaced at intervals of 2nm to form a column vector {D j}, together with the height H = 100nm, are input into the microscopic imaging simulation model to obtain each dimension value D j The corresponding defocused image sequence is then stacked to form a corresponding image for each size value D j Simulated through-focus scan image.

[0074] Furthermore, the microscopic imaging simulation model is expressed as:

[0075]

[0076] in, It represents the scattered near field formed by the plane wave component obtained by decomposing the Kohler illumination field and incident on the device surface. (x0, y0) is the object plane coordinate, (x, y) is the image plane coordinate, θ, They represent the x-component and y-component of the direction cosine angle of the plane wave component, (f x ,f y ) represents the spatial frequency corresponding to (x,y), H(f x ,f y ) represents the generalized pupil function including the defocus phase factor, and the “…” in the formula represents the omitted integral symbol. H(f x ,f y ) is:

[0077]

[0078] Where Z represents the defocus amount and CNA represents the imaging numerical aperture.

[0079] For each size p j are input into the microscopic imaging simulation model to obtain each size p jThe corresponding simulated through-focus scan image.

[0080] In one embodiment of the present invention, performing principal component decomposition on a simulated through-focus scanning image to obtain a principal component coefficient matrix includes the following specific steps.

[0081] S31, connect all row vectors of the simulated through-focus scanning image head to tail and transpose them to obtain column vector A j ;

[0082] S32, the column vector A of all simulated through-focus scanning images j Composition feature matrix A=[A1,A2,…,A j ,……A N ];

[0083] S33, performing principal component decomposition on the feature matrix A to obtain a principal component matrix and a principal component coefficient matrix.

[0084] Among them, A j Corresponding to size p j The simulated through-focus scanning image of the nanodevice, N is the size value set {p j The through-focus scan image is a two-dimensional image. The row vectors of the two-dimensional image are sequentially spliced ​​and transposed, that is, the two-dimensional image features are converted into column vector representations. The column vector representations of the two-dimensional images of all sizes are obtained, and then the column vector representations are obtained according to the size p. j The order of the feature matrix A, where the size is p j The order is the order of the size value set, arranged from small to large.

[0085] To perform principal component decomposition on the feature matrix A, you can call the function pca in MATLAB, that is:

[0086] [PCC,PC]=pca(A) (4)

[0087] Among them, PC is the principal component matrix, and PCC is the principal component coefficient matrix. Figure 4 The figure shows the result of principal component decomposition of feature matrix A.

[0088] Furthermore, after obtaining the principal component coefficient matrix, according to the size value set {p j} and the principal component coefficient matrix PCC to establish a regression matrix, and call the multivariate linear regression function regress in MATLAB to obtain the value set {p j} to the principal component coefficient matrix PCC, as shown in formula (5).

[0089] RM=regress(PCC,{p j}) (5)

[0090] Where RM represents the regression matrix, regress(·) is the multiple linear regression function, PCC represents the principal component coefficient matrix, {p j} is a set of size values, {p j}={p1,p2,…,p j ,…,p N}.

[0091] The principal components of any two images are orthogonal and uncorrelated, and there is a strong linear relationship between the principal component coefficient and the shape size, thus avoiding the influence of data crosstalk on the measurement results and improving the measurement accuracy.

[0092] When performing reverse inversion, the measured through-focus scanning image of the nanodevice to be measured is first decomposed into principal components to obtain a measured principal component coefficient matrix, and then the regression matrix is ​​reversely inverted based on the measured principal component coefficient matrix to obtain the measurement result.

[0093] Specifically, the measured principal component coefficient matrix can be obtained by fitting the column vector representation CS of the measured through-focus scan image with the principal component matrix PC of the simulated through-focus scan image through the least squares method, as shown in the following formula:

[0094] RPCC=pinv(PC)*CS

[0095] Where RPCC represents the measured principal component coefficient matrix, PC represents the principal component matrix of the characteristic matrix A of the simulated through-focus scan image, and CS is the column vector representation of the measured through-focus scan image. Like the column vector representation of the simulated through-focus scan image, CS is obtained by sequentially concatenating and transposing the row vectors of the two-dimensional image.

[0096] In one embodiment, a through-focus scan of the nanodevice to be measured is performed using a metallographic microscope in bright field mode to obtain a measured through-focus scan image. Specifically:

[0097] S51, first place the nanodevice to be tested on the microscope stage and adjust it to the focus distance Z0 of the metallographic microscope;

[0098] S52, collecting an actual defocused image of the nanodevice to be tested at fixed step lengths within the range [Z0-Z, Z0+Z];

[0099] S53 , stacking the actual defocused images into a three-dimensional image block according to the defocused acquisition sequence, and taking the XZ cross-section of the three-dimensional image block to obtain a measured through-focus scanning image.

[0100] The brightfield mode uses vertical incident light (Köhler illumination). The light passes through the objective lens and hits the sample surface, then reflects back to the objective lens to form an image. Compared with other models, the brightfield mode is sensitive to small height changes in surface topography, and the intensity of edge scattered light changes more significantly when out of focus.

[0101] Taking the measurement of nanocylinder structures as an example, after placing the nanocylinder to be measured on the microscope stage, the metallographic microscope is set to an illumination numerical aperture of INA0 = 0.1, an imaging numerical aperture of CNA0 = 0.75, an illumination wavelength of λ0 = 400 nm, a TE polarization state, and a magnification of M = 50. The nanocylinder is adjusted to a roughly in-focus position, set to Z = 0. The stage is then controlled to move downward to Z = -2 μm, and a defocused image is captured every 2 nm until the stage moves to Z = +2 μm above the initial focus position. All defocused images are stacked at their corresponding focal points to form an image block. An XZ cross-section of the image block is taken through the midpoint of the Y axis of the defocused image to obtain the measured through-focus scan image of the nanocylinder.

[0102] Furthermore, the least squares method is used to perform inverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain the measurement results.

[0103] Through the method of the present invention, in actual measurement, it is only necessary to perform principal component decomposition on the measured image once and call the regression model inversion, avoiding the complex real-time grayscale matching calculation in the traditional method, while ensuring accuracy and significantly reducing the calculation time.

[0104] See also Figure 5 The measurement error results shown in the figure show that the nanocylinder device was measured 10 times using the method of the present invention and the traditional TSOM method based on grayscale OIR values. The measured mean cylinder diameters were 154.4nm and 158nm, respectively, with measurement errors of 1.4nm and 5nm, respectively. This shows that the method of the present invention reduces the measurement error to 1 / 4 of that of traditional TSOM.

[0105] An embodiment of the present invention further provides a nanometer size measurement device based on a through-focus scanning image, comprising:

[0106] A priori value module, used to determine a size value set based on the priori shape and size of the nanodevice to be measured;

[0107] A simulation modeling module, for establishing a simulated through-focus scanning image of each dimension value in the dimension value set;

[0108] A principal component extraction module is used to perform principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix;

[0109] A regression modeling module is used to establish a regression matrix based on the size value set and the principal component coefficient matrix;

[0110] The principal component extraction module is further used to perform principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured to obtain a measured principal component coefficient matrix;

[0111] The reverse inversion module is used to perform reverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain the measurement results.

[0112] An embodiment of the present invention further provides an electronic device comprising a processor and a memory, wherein the number of processors may be one or more. The memory, as a computer-readable storage medium, can be used to store software programs, computer-executable programs, and modules. The processor executes the software programs, instructions, and modules stored in the memory to perform various functional applications and data processing of the electronic device, thereby implementing the nanometer size measurement method based on through-focus scanning images according to any of the above-mentioned embodiments of the present invention.

[0113] The memory may primarily include a program storage area and a data storage area. The program storage area may store an operating system and at least one application required for a function; the data storage area may store data generated based on the use of the terminal, etc. Furthermore, the memory may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state memory device. In some instances, the memory may further include memory remotely located relative to the processor, and these remote memories may be connected to the electronic device via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0114] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the nanometer size measurement method based on through-focus scanning images according to any embodiment of the present invention is implemented.

[0115] The computer storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, a computer-readable storage medium can be any tangible medium that contains or stores a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0116] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0117] An embodiment of the present invention further provides a computer program product. When the computer program product is run on a computer, the computer is enabled to execute the nanometer size measurement method based on through-focus scanning images according to any of the above embodiments of the present invention.

[0118] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nanometer size measurement method based on through-focus scanning images, characterized in that: include: Determine a size value set according to the prior morphological size of the nanodevice to be measured; Creating a simulated through-focus scanning image for each size in the size value set; performing principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix; Establishing a regression matrix based on the size value set and the principal component coefficient matrix; performing principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured to obtain a measured principal component coefficient matrix; The measured principal component coefficient matrix is ​​reversely inverted according to the regression matrix to obtain a measurement result.

2. The nanometer size measurement method based on through-focus scanning image according to claim 1, characterized in that: Creating a simulated through-focus scan image of each size in the size value set, including: The size p j Input the microscopic imaging simulation model and obtain the size p j Defocused image sequence of nanodevices; The defocused image sequence is stacked into a three-dimensional image block according to the defocused acquisition order, and a cross section of the three-dimensional image block is obtained with a size of p. j Simulated through-focus scanning image of the nanodevice.

3. The nanometer size measurement method based on through-focus scanning image according to claim 2, characterized in that: The microscopic imaging simulation model is expressed as: Among them, "..." indicates the omitted integral symbol, It represents the scattered near field formed by the plane wave component obtained by decomposing the Kohler illumination field and incident on the device surface. (x0, y0) is the object plane coordinate, (x, y) is the image plane coordinate, θ, They represent the x-component and y-component of the direction cosine angle of the plane wave component, (f x ,f y ) represents the spatial frequency corresponding to (x,y), H(f x ,f y ) represents the generalized pupil function including the defocus phase factor, which is expressed as: Where Z represents the defocus amount and CNA represents the imaging numerical aperture.

4. The nanometer size measurement method based on through-focus scanning image according to claim 1, characterized in that: The simulated through-focus scanning image is subjected to principal component decomposition to obtain a principal component coefficient matrix, including: Connect all the row vectors of the simulated through-focus scanning image head to tail and transpose them to get the column vector A j ; The column vector A of all simulated through-focus scan images j Composition feature matrix A=[A1,A2,…,A j ,……A N ], where A j Corresponding to size p j The simulated through-focus scanning image of the nanodevice, N is the size value set {p j } the number of sizes in the Perform principal component decomposition on the feature matrix A to obtain the principal component matrix and the principal component coefficient matrix.

5. The nanometer size measurement method based on through-focus scanning image according to claim 4, characterized in that: A regression matrix is ​​established based on the size value set and the principal component coefficient matrix, including: For the principal component coefficient matrix and size value set {p j } Perform multiple linear regression operation and obtain the set of size values ​​{p j } to the principal component coefficient matrix, expressed as: RM=regress(PCC,{p j }) Where RM represents the regression matrix, regress(·) is the multiple linear regression function, PCC represents the principal component coefficient matrix, {p j } is a set of size values.

6. The nanometer size measurement method based on through-focus scanning image according to claim 1, characterized in that: The measured through-focus scanning image is acquired by a metallographic microscope in bright field mode, and the acquisition method includes: Place the nanodevice to be tested on the microscope stage and adjust it to the focusing distance Z0 of the metallographic microscope; Collecting the actual defocused image of the nanodevice to be tested at fixed step lengths within the range of [Z0-Z, Z0+Z]; The actual defocused images are stacked into a three-dimensional image block according to the defocused acquisition sequence, and a cross section of the three-dimensional image block is taken to obtain a measured through-focus scanning image.

7. The nanometer size measurement method based on through-focus scanning images according to claim 6, characterized in that: Performing reverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain a measurement result includes: performing reverse inversion using a least squares method to obtain the measurement result.

8. A nanometer size measuring device based on through-focus scanning images, characterized in that: include: A priori value module, used to determine a size value set based on the priori shape and size of the nanodevice to be measured; A simulation modeling module, configured to establish a simulated through-focus scanning image of each dimension value in the dimension value set; a principal component extraction module, configured to perform principal component decomposition on the simulated through-focus scanning image to obtain a principal component coefficient matrix; A regression modeling module, configured to establish a regression matrix based on the size value set and the principal component coefficient matrix; The principal component extraction module is further configured to perform principal component decomposition on the measured through-focus scanning image of the nanodevice to be measured, to obtain a measured principal component coefficient matrix; The inverse inversion module is used to perform inverse inversion on the measured principal component coefficient matrix according to the regression matrix to obtain a measurement result.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the nanometer size measurement method based on through-focus scanning images according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the nanometer size measurement method based on through-focus scanning images according to any one of claims 1 to 7 is implemented.

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