Scanning image correction method and device and scanning type electron beam detection imaging system

Abstract

The invention relates to a scanning image correction method and device and a scanning type electron beam detection imaging system. The method comprises the following steps: determining correction parameters; determining deflector excitation according to the correction parameters; based on deflector excitation, scanning and sampling a morphology image of the square pattern sample; obtaining morphology parameters of the morphology image; according to the morphology parameters of the morphology image, the distortion of the morphology image is quantified; if the distortion is greater than or equal to a target threshold value, adjusting a correction parameter based on the distortion, updating deflector excitation according to the adjusted correction parameter, and re-scanning the morphology image of the square pattern sample based on the updated deflector excitation until the distortion of the morphology image is less than the target threshold value; and if the distortion is smaller than the target threshold, determining the correction parameter as a target correction parameter, and finally correcting the scanned image according to the target correction parameter. According to the invention, distortion of the scanned image can be corrected.

Description

Technical Field

[0001] This application relates to the field of semiconductor quantity detection technology, and in particular to a scanning image correction method and apparatus, and a scanning electron beam detection imaging system. Background Technology

[0002] As chip manufacturing precision continues to increase, the demand for measurement accuracy in semiconductor metrology technology is also rising. Scanning electron beam imaging systems, such as scanning electron microscopes, can rely on precise electron beam control to scan and inspect nanoscale patterns.

[0003] Currently, in scanning electron beam imaging systems, the structure and manufacturing process of the deflector play a decisive role in the imaging performance of the system. The deflector can employ electrodes or coils to generate mutually orthogonal electric or magnetic fields. Through electric force or Lorentz force, the electron beam is deflected in two independent directions, thereby achieving scanning imaging of the surface of the structure under test.

[0004] However, in the actual manufacturing and installation process of the deflector, the spacing between the deflector electrodes or magnetic poles is not completely consistent, and the installation angle of the deflector may also have certain deviations, which can easily lead to some distortion in the scanned image. Even with extremely high precision requirements for the manufacturing and installation of the deflector, the risk of image distortion is still unavoidable for ultra-high precision scanning imaging observation. Summary of the Invention

[0005] Based on this, embodiments of this application provide a scanning image correction method and apparatus, and a scanning electron beam detection imaging system, which can effectively reduce the risk of distortion in scanning images and correct distortion in scanning images.

[0006] To achieve the above objectives, some embodiments of this application provide a scanning image correction method applied to a scanning electron beam detection imaging system. The scanning image correction method includes:

[0007] Determine the correction parameters;

[0008] Determine the deflector excitation based on the correction parameters;

[0009] Based on deflector excitation, the topographic image of the sampled square pattern is scanned;

[0010] Obtain the morphological parameters of the morphological image;

[0011] The distortion of the topographic image is quantified based on the topographic parameters of the topographic image;

[0012] If the distortion is greater than or equal to the target threshold, the correction parameters are adjusted based on the distortion, and the deflector excitation is updated according to the adjusted correction parameters. The topography image of the sampled square pattern is rescanned based on the updated deflector excitation until the distortion of the topography image is less than the target threshold.

[0013] If the distortion is less than the target threshold, the correction parameter is determined as the target correction parameter, and the scanned image is corrected according to the target correction parameter.

[0014] In some embodiments of this application, the scanning electron beam detection imaging system includes at least one set of scanning deflectors, and each set of scanning deflectors includes a first deflector and a second deflector to generate deflection forces in the X and Y directions, respectively.

[0015] Accordingly, determining the correction parameters includes:

[0016] Obtain the circuit gain and deflection sensitivity of the first and second deflectors;

[0017] Determine the first angle between the mechanical mounting direction of the first deflector and the corresponding first scanning direction, and the second angle between the mechanical mounting direction of the second deflector and the corresponding second scanning direction;

[0018] Based on the circuit gain, deflection sensitivity, first included angle and second included angle, the excitation correction formulas for the first deflector and the second deflector are determined respectively.

[0019] Based on the excitation correction formula, the correction parameters are determined.

[0020] In some embodiments of this application, the excitation correction formula for the first deflector is:

[0021] ;

[0022] The excitation correction formula for the second deflector is:

[0023] ;

[0024] Where DX is the excitation of the first deflector, DY is the excitation of the second deflector, g is the circuit gain, and s x The deflection sensitivity of the first deflector is s. y The deflection sensitivity of the second deflector is given by θ, where i and j are the coordinates of the scanning point in the two-dimensional scanning coordinate system, and θ is the deflection sensitivity of the second deflector. x Let θ be the first included angle. y This is the second included angle.

[0025] Accordingly, the correction parameters include: a first correction parameter λ and a second correction parameter δθ. Wherein,

[0026] First corrective parameter ;

[0027] Second corrective parameter .

[0028] In some embodiments of this application, determining the deflector excitation based on the correction parameters includes:

[0029] Based on the correction parameters, the excitation formula for the first deflector is determined as follows:

[0030] ;

[0031] The excitation of the first deflector is determined according to the excitation formula of the first deflector;

[0032] Based on the correction parameters, the excitation formula for the second deflector is determined as follows:

[0033] ;

[0034] The excitation of the second deflector is determined according to the excitation formula of the second deflector.

[0035] In some embodiments of this application, the scanning electron beam detection imaging system includes multiple sets of scanning deflectors. The scanning image correction method further includes: determining the correction parameters corresponding to each set of scanning deflectors one by one; and determining the target correction parameters for the corresponding set of scanning deflectors based on each correction parameter.

[0036] In some embodiments of this application, the shape parameters of the shape image include: width, height, and interior angles. Obtaining the shape parameters of the shape image includes:

[0037] Identify the target boundaries corresponding to each boundary in the topography image of the square pattern sample;

[0038] Based on edge detection, multiple target points on the target boundary are identified, and an expression function of the target boundary is fitted according to each target point.

[0039] The width, height, and interior angles of the topographic image are determined based on the expression functions of each target boundary.

[0040] In some embodiments of this application, the expression function of the target boundary includes:

[0041] ;

[0042] Where x and y are the coordinates of the target point in the two-dimensional scanning coordinate system, A is the first scaling factor, B is the second scaling factor, and C is a constant.

[0043] Accordingly, determining the width, height, and interior angles of the topography image based on the expression functions of each target boundary includes:

[0044] The expression function for obtaining the first target boundary is:

[0045] ,

[0046] The expression function for the second objective boundary is:

[0047] ;

[0048] If the first target boundary and the second target boundary are opposite each other in the first scanning direction, then the distance between the first target boundary and the second target boundary is determined to be the width;

[0049] If the first target boundary and the second target boundary are opposite each other in the second scanning direction, then the distance between the first target boundary and the second target boundary is determined as the height; wherein the first scanning direction is orthogonal to the second scanning direction;

[0050] If the first target boundary and the second target boundary are adjacent, then the included angle between the first target boundary and the second target boundary is determined as the corresponding interior angle;

[0051] Wherein, the distance is , ,

[0052] ;

[0053] The included angle

[0054] .

[0055] In some embodiments of this application, the correction parameters include: a first correction parameter λ and a second correction parameter δθ. The step of quantifying the distortion of the topography image based on the topography parameters of the topography image includes:

[0056] The quantization function for distortion is defined as follows:

[0057] ;

[0058] Where J is the distortion, a is the first weighting coefficient, θ1 is the first interior angle, θ2 is the second interior angle, θ3 is the third interior angle, θ4 is the fourth interior angle, b is the second weighting coefficient, w is the width, and h is the height; the first, second, third, and fourth interior angles are arranged clockwise, and the first and third interior angles are diagonal, as are the second and fourth interior angles;

[0059] The distortion is calculated and determined based on the distortion quantization function.

[0060] On the other hand, some embodiments of this application also provide a scanned image correction apparatus for implementing the scanned image correction method as described in any of the preceding embodiments. The scanned image correction apparatus includes an acquisition module, a distortion reduction module, and a distortion correction module.

[0061] The acquisition module is used to acquire the morphological image of a square pattern sample under deflector excitation, as well as the morphological parameters of the morphological image; wherein, the deflector excitation is determined iteratively based on the correction parameters or the adjusted correction parameters.

[0062] The distortion quantification module is connected to the acquisition module and is used to quantify the distortion of the topography image based on the topography parameters of the topography image.

[0063] The distortion correction module is connected to the distortion quantification module and is used to determine whether the distortion is less than the target threshold, and: when the distortion is less than the target threshold, the correction parameter is determined as the target correction parameter, so as to correct the scanned image according to the target correction parameter; when the distortion is greater than or equal to the target threshold, the correction parameter is adjusted based on the distortion until the distortion of the morphology is less than the target threshold.

[0064] In another aspect, some embodiments of this application also provide a scanning electron beam detection imaging system, including the scanning image correction device as described in any of the preceding embodiments.

[0065] The embodiments of this application may have, or at least have, the following advantages:

[0066] In this embodiment, after pre-determining the correction parameters, the deflector excitation can be output based on the correction parameters, and the topographic image of the sampled square pattern can be scanned. Then, the distortion of the topographic image can be easily quantified using the topographic parameters. Finally, the correction parameters are adjusted iteratively or output based on the relationship between the distortion and the target threshold. Therefore, this embodiment easily achieves automated correction of the scanned image through iterative correction of the correction parameters, and can efficiently compensate for various deflector position deviations caused by mechanical errors, reducing the precision of the deflector's mechanical manufacturing process and installation difficulty. Simultaneously, it effectively reduces the risk of distortion in the scanned image, correcting distortion and thus improving the imaging performance of the scanning electron beam detection imaging system.

[0067] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 This is a flowchart illustrating a scanned image correction method provided in some embodiments;

[0070] Figure 2 One of the embodiments provided Figure 1 A flowchart illustrating step 100 in the method shown;

[0071] Figure 3 This is an equivalent schematic diagram of the angle between the mechanical mounting direction of a deflector and the corresponding scanning direction provided in some embodiments;

[0072] Figure 4 One of the embodiments provided Figure 1 A flowchart illustrating step 200 in the method shown;

[0073] Figure 5 One of the embodiments provided Figure 1 A flowchart illustrating step 400 in the method shown;

[0074] Figure 6 This is a schematic diagram illustrating the identification of a target boundary provided in some embodiments;

[0075] Figure 7 This is a schematic diagram of the morphological parameters of a square patterned sample corresponding to a morphological image provided in some embodiments;

[0076] Figure 8 One of the embodiments provided Figure 1 A flowchart illustrating step 500 in the method shown;

[0077] Figure 9 This is a simulation diagram of a scanning pattern provided in some embodiments;

[0078] Figure 10 This is a simulation diagram of another scanning pattern provided in some embodiments;

[0079] Figure 11 This is a comparative schematic diagram of the initial sampling pattern and the corrected pattern of a square pattern sample provided in some embodiments;

[0080] Figure 12 This is a structural block diagram of a scanned image correction device provided in some embodiments;

[0081] Figure 13 This is a structural block diagram of another scanned image correction device provided in some embodiments.

[0082] Explanation of reference numerals in the attached figures:

[0083] 10 - Acquisition module, 20 - Distortion transformation module, 30 - Distortion correction module, 40 - Excitation generation module;

[0084] 11-First electrode, 12-Second electrode, 21-Third electrode, 22-Fourth electrode;

[0085] m - scan point, N - initial sampling pattern, N' - corrected pattern. Detailed Implementation

[0086] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0087] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0088] It should be understood that when an element or layer is referred to as being "on," "adjacent to," or "connected to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. It should be understood that although the terms "first," "second," etc., may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be referred to as a second element, component, region, layer, or portion.

[0089] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “comprise” and / or “comprising” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0090] Currently, the realization of electron beam scanning imaging in scanning electron beam detection imaging systems mainly involves converting timing signals into specific timing analog signals using digital circuits, and then transmitting these timing analog signals to a pair of scanning deflectors that are orthogonal to each other in the scanning field. However, it is understandable that, due to limitations in the actual manufacturing process and installation deviations of the deflectors, there is a risk that the scanning deflectors, which should be orthogonal, may not be orthogonal, inevitably causing distortion in the scanned image.

[0091] Based on this, some embodiments of this application provide a scanning image correction method applied to a scanning electron beam detection imaging system. This method can compensate for the scanning signal of a deflector with a non-orthogonal scanning field to generate an orthogonal scanning field, thereby avoiding distortion of the scanning image caused by installation errors of the deflector, etc. In other words, it can effectively reduce the risk of distortion of the scanning image and correct the distortion of the scanning image.

[0092] Please see Figure 1 The scanning image correction method provided in this application includes the following steps S100~S700.

[0093] S100, determine the correction parameters.

[0094] S200 determines the deflector excitation based on the correction parameters.

[0095] The S300, based on deflector excitation, scans and samples the topographic image of square patterned samples.

[0096] Optionally, the morphological image of the square patterned sample is acquired using a scanning electron beam detection imaging system. Scanning electron beam detection imaging systems include, but are not limited to, scanning electron microscope systems.

[0097] Optionally, the square patterned sample is pre-positioned in the center of the field of view of the scanning electron beam detection imaging system.

[0098] S400, Obtain the morphological parameters of the morphological image.

[0099] S500, quantify the distortion of the topography image based on the topography parameters of the topography image.

[0100] S600, in response to the distortion being greater than or equal to the target threshold, the correction parameters are adjusted based on the distortion, and the deflector excitation is updated according to the adjusted correction parameters. The topography image of the sampled square pattern is rescanned based on the updated deflector excitation until the distortion of the topography image is less than the target threshold.

[0101] S700, if the distortion is less than the target threshold, then the correction parameter is determined as the target correction parameter, so as to correct the scanned image according to the target correction parameter.

[0102] In this embodiment, after pre-determining the correction parameters, the deflector excitation can be output based on the correction parameters, and the topographic image of the sampled square pattern can be scanned. Then, the distortion of the topographic image can be easily quantified using the topographic parameters. Finally, the correction parameters are adjusted iteratively or output based on the relationship between the distortion and the target threshold. Therefore, this embodiment easily achieves automated correction of the scanned image through iterative correction of the correction parameters, and can efficiently compensate for various deflector position deviations caused by mechanical errors, thereby reducing the precision of the deflector's mechanical manufacturing process and the difficulty of installation. Simultaneously, it effectively reduces the risk of distortion in the scanned image, corrects distortion in the scanned image, and thus improves the imaging performance of the scanning electron beam detection imaging system.

[0103] In some embodiments of this application, the scanning electron beam detection imaging system includes at least one set of scanning deflectors, and each set of scanning deflectors includes a first deflector and a second deflector.

[0104] Accordingly, please refer to Figure 2 In step S100, the correction parameters are determined, including the following steps S110 to S140.

[0105] S110, obtain the circuit gain and deflection sensitivity of the first deflector and the second deflector.

[0106] S120, determine the first angle between the mechanical mounting direction of the first deflector and the corresponding first scanning direction, and the second angle between the mechanical mounting direction of the second deflector and the corresponding second scanning direction.

[0107] S130, based on the circuit gain, deflection sensitivity, first included angle and second included angle, determine the excitation correction formulas for the first deflector and the second deflector respectively.

[0108] S140, based on the excitation correction formula, determine the correction parameters.

[0109] For example, a set of scanning deflectors typically consists of a series of symmetrically arranged scanning coils or metal electrodes, such as a four-coil structure, a four-electrode structure, an eight-electrode structure, or a twelve-electrode structure. Figure 3The following illustration uses a four-electrode structure for the scanning deflector. The first deflector, for example, consists of a first electrode 11 and a second electrode 12. The first electrode 11 can be applied with a negative excitation -DX, and the second electrode 12 can be applied with a positive excitation DX. The second deflector, for example, consists of a third electrode 21 and a fourth electrode 22. The third electrode 21 can be applied with a positive excitation DY, and the fourth electrode 22 can be applied with a negative excitation -DY. Here, the polarity of the excitation on each electrode can be matched to the scanning direction setting; this embodiment does not specifically limit this.

[0110] Please continue reading. Figure 3 The mechanical mounting direction of the first deflector is X', and the mechanical mounting direction of the second deflector is Y'. The first scanning direction is X, and the second scanning direction is Y. The angle between the mechanical mounting direction of the first deflector and the corresponding first scanning direction is the first angle θ. x The angle between the mechanical mounting direction of the second deflector and the corresponding second scanning direction is the second angle θ. y Ideally, the deflection fields generated by the first and second deflectors are orthogonal, i.e., the first included angle θ. x The second included angle θ y Equal, for example, θ x =θ y =θ. Thus, defining DX as the excitation of the first deflector, DY as the excitation of the second deflector, g as the circuit gain, s as the deflection sensitivity of the deflector, and i and j as the coordinates of the scanning point in the two-dimensional scanning coordinate system, the relationship between the deflector excitation and the corresponding scanning direction can be obtained based on linear rotation transformation as follows:

[0111] ;

[0112] .

[0113] Considering the actual installation error of the deflectors, the deflection fields generated by the first and second deflectors are not orthogonal. (Defining s...) x The deflection sensitivity of the first deflector is s. y After determining the deflection sensitivity of the second deflector, we can obtain:

[0114] The excitation correction formula for the first deflector is as follows:

[0115] ;

[0116] The excitation correction formula for the second deflector is as follows:

[0117] .

[0118] Therefore, it can be understood that the distortion of the scanned image is caused by two reasons: first, the deflection fields generated by the first deflector and the second deflector are not orthogonal; and second, the difference in deflection sensitivity between the first deflector and the second deflector.

[0119] Based on this, optionally, the correction parameters are defined as a first correction parameter λ and a second correction parameter δθ; wherein, the first correction parameter... Second correction parameter This facilitates the correction and adjustment of the deflector excitation.

[0120] Please refer to some embodiments of this application. Figure 4 In step S200, the deflector excitation is determined based on the correction parameters, including the following steps S210~S240.

[0121] S210, based on the correction parameters, the excitation formula for the first deflector is determined as follows:

[0122] .

[0123] S220, determine the excitation of the first deflector according to the excitation formula of the first deflector.

[0124] S230, based on the correction parameters, the excitation formula for the second deflector is determined as follows:

[0125] .

[0126] S240, determine the excitation of the second deflector according to the excitation formula of the second deflector.

[0127] In this embodiment, by adjusting the first correction parameter λ and the second correction parameter δθ, the excitation of the first deflector and the excitation of the second deflector can be corrected and adjusted to obtain an orthogonal scanning field and a scanning image that meets the expectations. This allows for better calibration of the scanning image distortion caused by the mechanical installation error of the deflector, thereby completing the distortion correction of the scanning image.

[0128] It should be added that, in some embodiments of this application, the scanning electron beam detection imaging system includes multiple sets of scanning deflectors. The scanning image correction method further includes: determining the correction parameters corresponding to each set of scanning deflectors one by one; and determining the target correction parameters for the corresponding set of scanning deflectors based on each correction parameter. Thus, for embodiments with multiple sets of scanning deflectors, the aforementioned method for correcting the deflector excitation in a set of scanning deflectors can be used to correct the deflector excitation of different sets of scanning deflectors separately, and then the sets of scanning deflectors in the scanning electron beam detection imaging system can be used together based on each target correction parameter.

[0129] It is worth mentioning that, in some embodiments of this application, the topographic parameters of the topographic image corresponding to the square pattern sample include: width, height, and each interior angle. Please refer to... Figure 5 Step S400 involves obtaining the morphological parameters of the morphological image, including the following steps S410 to S430.

[0130] S410, Identify the target boundaries corresponding to each boundary in the topography image of the square pattern sample.

[0131] Optionally, please refer to Figure 6 The preset boundary recognition algorithm identifies the regions where the top, bottom, left, and right boundaries of the square pattern sample are located in the topography image, and determines them as target boundaries (e.g., first boundary L1, second boundary L2, third boundary L3, and fourth boundary L4).

[0132] Here, the boundary recognition algorithm can be set according to requirements. This application embodiment does not specifically limit it, to ensure that the preset boundary recognition algorithm can identify and output, for example, pixels. Figure 6 The different target boundaries shown include, for example, the distance between opposite sides, and the angle between adjacent sides (or the difference between the angle between adjacent sides and 90°).

[0133] S420, based on edge detection, determines multiple target points on the target boundary and fits an expression function of the target boundary based on each target point.

[0134] Optionally, based on each target point, the expression function of the target boundary can be fitted using the least squares method.

[0135] Alternatively, the expression function of the target boundary can be represented as:

[0136] ;

[0137] Where x and y are the coordinates of the target point in the two-dimensional scanning coordinate system, A is the first scaling factor, B is the second scaling factor, and C is a constant.

[0138] S430, determine the width, height and interior angle of the topography image based on the expression function of each target boundary.

[0139] For example, please combine Figure 6 and Figure 7 It is understood that in step S430, the width, height, and interior angle of the topography image are determined according to the expression function of each target boundary, including the following steps S431 to S434.

[0140] S431, the expression function for obtaining the first target boundary is:

[0141] ,

[0142] The expression function for the second objective boundary is: .

[0143] S432, if the first target boundary and the second target boundary are opposite each other in the first scanning direction, then the distance between the first target boundary and the second target boundary is determined as the width.

[0144] Optionally, the first scanning direction is the X direction, the first target boundary is, for example, the first boundary L1, the second target boundary is, for example, the third boundary L3, and the width is w.

[0145] S433, if the first target boundary and the second target boundary are opposite each other in the second scanning direction, then the distance between the first target boundary and the second target boundary is determined as the height; wherein the first scanning direction is orthogonal to the second scanning direction.

[0146] Optionally, the second scanning direction is the Y direction, the first target boundary is, for example, the second boundary L2, the second target boundary is the fourth boundary L4, and the height is h.

[0147] It can be understood that the distance between the first target boundary and the second target boundary in steps S432 and S433 above can be expressed by the formula d= Obtained through calculation.

[0148] Where d is the distance. , .

[0149] S434, if the first target boundary and the second target boundary are adjacent, then the included angle between the first target boundary and the second target boundary is determined as the corresponding interior angle.

[0150] Optionally, the first target boundary is, for example, the first boundary L1, the second target boundary is, for example, the second boundary L2, and the corresponding interior angle is the first interior angle θ1.

[0151] Optionally, the first target boundary is, for example, the second boundary L2, the second target boundary is, for example, the third boundary L3, and the corresponding interior angle is the second interior angle θ2.

[0152] Optionally, the first target boundary is, for example, the third boundary L3, and the second target boundary is, for example, the fourth boundary L4, with the corresponding interior angle being the third interior angle θ3.

[0153] Optionally, the first target boundary is, for example, the fourth boundary L4, and the second target boundary is, for example, the first boundary L1, with the corresponding interior angle being the fourth interior angle θ4.

[0154] It can be understood that the angle between the first target boundary and the second target boundary in step S434 above can be obtained through the formula

[0155]

[0156] The angle is calculated, where θ is the included angle. Furthermore, the first interior angle θ1, the second interior angle θ2, the third interior angle θ3, and the fourth interior angle θ4 can be obtained one by one.

[0157] In some embodiments of this application, the correction parameters include: a first correction parameter λ and a second correction parameter δθ. Accordingly, please refer to... Figure 7 In step S500, the distortion of the topography image is quantified according to the topography parameters of the topography image, including the following steps S510 and S520.

[0158] S510, the quantization function for distortion is defined as follows:

[0159] ;

[0160] Where J is the distortion, a is the first weighting coefficient, θ1 is the first interior angle, θ2 is the second interior angle, θ3 is the third interior angle, θ4 is the fourth interior angle, b is the second weighting coefficient, w is the width, and h is the height; the first, second, third, and fourth interior angles are arranged clockwise, and the first and third interior angles are diagonal, as are the second and fourth interior angles.

[0161] Here, the first weight coefficient a is the weight coefficient of the first correction parameter λ in the distorted value, and the second weight coefficient b is the weight coefficient of the second correction parameter δθ in the distorted value. The specific weight coefficients can be set according to the requirements.

[0162] S520 calculates and determines the distortion based on the distortion quantization function.

[0163] For example, when the first weight coefficient a=1 and the second weight coefficient b=0.1, the target threshold is 1.

[0164] In this embodiment, the distortion of the scanned image can be quantified by the distortion quantization function, which facilitates the iteration or output of correction parameters (including the first correction parameter λ and the second correction parameter δθ) by comparing the numerical value between the distortion and the target threshold.

[0165] Here, through the iteration of the correction parameters (including the first correction parameter λ and the second correction parameter δθ), the distortion can be continuously reduced until the distortion is less than the target threshold, at which point the distortion of the scanned image is considered to have been corrected.

[0166] It should be added that the iterative adjustment of the correction parameters in this embodiment is based on the gradient descent algorithm, but it is not limited to this. Other iterative methods, such as direct iterative methods and Newton's method, which use multiple iterations to determine whether the distortion function has converged, are also applicable.

[0167] To more clearly illustrate the technical effects that the embodiments of this application can achieve, Figure 9 and Figure 10 Scanning simulations were performed with different scan image distortions, and the uncorrected scan image F1 and the corrected scan image F2 were compared.

[0168] For example, please refer to Figure 9 Before using the scanning image correction method provided in this application embodiment, the uncorrected scanning image F1 and the corresponding X channel signal and Y channel signal are as follows: Figure 9 As shown in Figure (A), assume there is a signal deviation between the excitation of the first deflector and the second deflector, and a first angle θ between the mechanical mounting direction of the first deflector and the corresponding first scanning direction. x =0°, correspondingly, after adopting the scanning image correction method provided in this application embodiment, under the conditions of the first correction parameter λ=0.9 and the second correction parameter δθ=5°, the corrected scanning image F2 and the corresponding X channel signal and Y channel signal are as follows: Figure 9 As shown in Figure (B) of the document. Figure 9 Figure (C) in the middle is Figure 9 (A) diagram and Figure 9 The superimposed comparison diagram in Figure (B) shows that, compared to the uncorrected scan image F1, the corrected scan image F2 has effectively corrected the image distortion in the uncorrected scan image F1.

[0169] For example, please refer to Figure 10 Before using the scanning image correction method provided in this application embodiment, the uncorrected scanning image F1 and the corresponding X channel signal and Y channel signal are as follows: Figure 10 As shown in Figure (A). Assume a first angle θ between the mechanical mounting direction of the first deflector and the corresponding first scanning direction. x =45°, after adopting the scanning image correction method provided in this application embodiment, under the conditions of first correction parameter λ=0.9 and second correction parameter δθ=5°, the corrected scanning image F2 and the corresponding X channel signal and Y channel signal are as follows: Figure 10 As shown in Figure (B) of the document. Figure 10 Figure (C) in the middle is Figure 10 (A) diagram and Figure 10The superimposed comparison diagram in Figure (B) shows that, compared to the uncorrected scan image F1, the corrected scan image F2 has effectively corrected the image distortion in the uncorrected scan image F1.

[0170] also, Figure 11 This diagram illustrates a comparison between the initial sampling pattern N and the corrected pattern N' of a square pattern sample. The initial sampling pattern N of the square pattern sample is shown below. Figure 11 As shown in Figure (A), image distortion exists due to the non-orthogonality of the deflectors and differences in their sensitivity. The corrected pattern N', after correcting the initial sampling pattern N using the scanning image correction method provided in this application, is, for example... Figure 11 As shown in Figure (B), the corrected pattern N' can be a standard square.

[0171] Some embodiments of this application also provide a scanned image correction apparatus for implementing the scanned image correction method as described in the foregoing embodiments. The scanned image correction apparatus also possesses the technical advantages of the aforementioned scanned image correction method, and will not be detailed here. Furthermore, the functional features of each component involved in this scanned image correction apparatus can also be found in the relevant descriptions in the foregoing embodiments.

[0172] Please see Figure 12 The scanned image correction device includes an acquisition module 10, a distortion reduction module 20, and a distortion correction module 30.

[0173] The acquisition module 10 is used to acquire the morphological image of the square pattern sample under the excitation of the deflector, and the morphological parameters of the morphological image; wherein, the deflector excitation is determined iteratively according to the correction parameters or the adjusted correction parameters.

[0174] The distortion quantification module 20 is connected to the acquisition module 10 and is used to quantify the distortion of the shape image based on the shape parameters of the shape image.

[0175] The distortion correction module 30 is connected to the distortion quantification module 20 and is used to determine whether the distortion is less than the target threshold, and: when the distortion is less than the target threshold, the correction parameter is determined as the target correction parameter, so as to correct the scanned image according to the target correction parameter; when the distortion is greater than or equal to the target threshold, the correction parameter is adjusted based on the distortion until the distortion of the morphology is less than the target threshold.

[0176] Please refer to some embodiments of this application. Figure 13The scanning image correction device further includes an excitation generation module 40 connected to the distortion correction module 30. The excitation generation module 40 is used to: acquire the circuit gain of the first deflector and the second deflector, the deflection sensitivity of the first deflector and the second deflector, the first angle between the mechanical mounting direction of the first deflector and the corresponding first scanning direction, and the second angle between the mechanical mounting direction of the second deflector and the corresponding second scanning direction; determine excitation correction formulas for the first deflector and the second deflector based on the circuit gain, deflection sensitivity, the first angle, and the second angle; determine correction parameters based on the excitation correction formulas; iteratively update the correction parameters in response to parameter adjustment commands from the distortion correction module 30; and output deflector excitation based on the correction parameters.

[0177] In some embodiments of this application, the acquisition module 10 is further configured to: identify the target boundaries corresponding to each boundary in the square pattern sample in the topography image; determine multiple target points on the target boundary based on edge detection, and fit an expression function of the target boundary according to each target point; and determine the width, height and interior angles of the topography image according to the expression function of each target boundary.

[0178] In some embodiments of this application, the distortion quantization module 20 is further configured to: define a quantization function for the distortion; and calculate and determine the distortion based on the quantization function for the distortion. For example, the quantization function for the distortion is as follows:

[0179] ;

[0180] Where J is the distortion, a is the first weighting coefficient, θ1 is the first interior angle, θ2 is the second interior angle, θ3 is the third interior angle, θ4 is the fourth interior angle, b is the second weighting coefficient, w is the width, and h is the height; the first, second, third, and fourth interior angles are arranged clockwise, and the first and third interior angles are diagonal, as are the second and fourth interior angles.

[0181] Here, the first weight coefficient a is the weight coefficient of the first correction parameter λ in the distorted value, and the second weight coefficient b is the weight coefficient of the second correction parameter δθ in the distorted value. The specific weight coefficients can be set according to the requirements.

[0182] For example, when the first weight coefficient a=1 and the second weight coefficient b=0.1, the target threshold is 1.

[0183] Some embodiments of this application also provide a scanning electron beam detection imaging system, including the scanning image correction device as described in any of the preceding embodiments. The scanning electron beam detection imaging system includes, but is not limited to, a scanning electron microscope system.

[0184] In the description of this specification, references to terms such as "some embodiments," "some examples," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0185] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0186] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A method for correcting scanned images, characterized in that, Applied to scanning electron beam detection imaging systems; the scanning image correction method includes: Determine the correction parameters; Determine the deflector excitation based on the correction parameters; Based on the deflector excitation, the topographic image of the sampled square pattern is scanned; Obtain the morphological parameters of the morphological image; The distortion of the topographic image is quantified based on the topographic parameters of the topographic image; If the distortion is greater than or equal to the target threshold, the correction parameter is adjusted based on the distortion, and the deflector excitation is updated according to the adjusted correction parameter. The topography image of the square pattern sample is rescanned based on the updated deflector excitation until the distortion of the topography image is less than the target threshold. If the distortion is less than the target threshold, the correction parameter is determined as the target correction parameter, and the scanned image is corrected according to the target correction parameter.

2. The scanned image correction method according to claim 1, characterized in that, The scanning electron beam detection imaging system includes at least one set of scanning deflectors, and each set of scanning deflectors includes a first deflector and a second deflector; wherein, determining the correction parameters includes: Obtain the circuit gain and deflection sensitivity of the first deflector and the second deflector; Determine the first angle between the mechanical mounting direction of the first deflector and the corresponding first scanning direction, and the second angle between the mechanical mounting direction of the second deflector and the corresponding second scanning direction; Based on the circuit gain, the deflection sensitivity, the first included angle, and the second included angle, the excitation correction formulas for the first deflector and the second deflector are determined respectively. The correction parameters are determined based on the excitation correction formula.

3. The scanned image correction method according to claim 2, characterized in that, The excitation correction formula for the first deflector is: ； The excitation correction formula for the second deflector is: ； Where DX is the excitation of the first deflector, DY is the excitation of the second deflector, g is the circuit gain, and s x s is the deflection sensitivity of the first deflector. y θ represents the deflection sensitivity of the second deflector, i and j are the coordinates of the scanning point in the two-dimensional scanning coordinate system, and θ is the deflection sensitivity of the second deflector. x Let θ be the first included angle. y This is the second included angle; The correction parameters include: a first correction parameter λ and a second correction parameter δθ; First correction parameter ; The second correction parameter .

4. The scanned image correction method according to claim 3, characterized in that, The step of determining the deflector excitation based on the correction parameters includes: Based on the correction parameters, the excitation formula for the first deflector is determined as follows: ； The excitation of the first deflector is determined according to the excitation formula of the first deflector; Based on the aforementioned correction parameters, the excitation formula for the second deflector is determined as follows: ； The excitation of the second deflector is determined according to the excitation formula of the second deflector.

5. The scanned image correction method according to claim 2, characterized in that, The scanning electron beam detection imaging system includes multiple sets of scanning deflectors; the scanning image correction method further includes: Determine the correction parameters corresponding to each group of scanning deflectors; Based on each of the aforementioned correction parameters, the target correction parameters of the corresponding group of scanning deflectors are determined respectively.

6. The scanned image correction method according to any one of claims 1 to 5, characterized in that, The shape parameters of the shape image include: width, height, and interior angles; obtaining the shape parameters of the shape image includes: Identify the target boundaries corresponding to each boundary in the topography image of the square pattern sample; Based on edge detection, multiple target points on the target boundary are determined, and an expression function of the target boundary is fitted according to each target point; The width, height, and interior angle of the topography image are determined based on the expression function of each target boundary.

7. The scanned image correction method according to claim 6, characterized in that, The expression function of the target boundary includes: ； Where x and y are the coordinates of the target point in the two-dimensional scanning coordinate system, A is the first scaling factor, B is the second scaling factor, and C is a constant; Determining the width, height, and interior angle of the topography image based on the expression function of each target boundary includes: The expression function for obtaining the first target boundary is: ， The expression function for the second objective boundary is: ； If the first target boundary and the second target boundary are opposite each other in the first scanning direction, then the distance between the first target boundary and the second target boundary is determined as the width; If the first target boundary and the second target boundary are opposite each other in the second scanning direction, then the distance between the first target boundary and the second target boundary is determined as the height; the first scanning direction is orthogonal to the second scanning direction; If the first target boundary and the second target boundary are adjacent, then the included angle between the first target boundary and the second target boundary is determined to be the corresponding interior angle; Wherein, the distance is , , ； The included angle 。 8. The scanned image correction method according to claim 6, characterized in that, The correction parameters include: a first correction parameter λ and a second correction parameter δθ; quantifying the distortion of the topography image based on the topography parameters includes: The quantization function for the distortion is defined as follows: ； Wherein, J is the distortion, a is the first weighting coefficient, θ1 is the first interior angle, θ2 is the second interior angle, θ3 is the third interior angle, θ4 is the fourth interior angle, b is the second weighting coefficient, w is the width, and h is the height; the first interior angle, the second interior angle, the third interior angle, and the fourth interior angle are arranged clockwise, and the first interior angle and the third interior angle are diagonal, and the second interior angle and the fourth interior angle are diagonal; The distortion is calculated and determined based on the quantization function of the distortion.

9. A scanning image correction device, characterized in that, include: The acquisition module is used to acquire a morphological image of a square pattern sample under deflector excitation, and the morphological parameters of the morphological image; wherein the deflector excitation is determined iteratively based on the correction parameters or the adjusted correction parameters; A distortion quantification module, connected to the acquisition module, is used to quantify the distortion of the topography image based on the topography parameters of the topography image; A distortion correction module, connected to the distortion quantification module, is used to determine whether the distortion is less than a target threshold, and: when the distortion is less than the target threshold, to determine the correction parameter as a target correction parameter, so as to correct the scanned image according to the target correction parameter; when the distortion is greater than or equal to the target threshold, to adjust the correction parameter based on the distortion until the distortion of the morphology image is less than the target threshold.

10. A scanning electron beam detection imaging system, characterized in that, include: The scanned image correction apparatus as described in claim 9.

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