Film thickness measuring method and system based on line scanning hyperspectral camera

Abstract

The invention discloses a film thickness measurement method and system based on a line scanning hyperspectral camera, and relates to the technical field of hyperspectral imaging, and the method comprises the steps: obtaining a reflection or transmission spectrum image and a dark noise image, and carrying out the denoising processing; using a hyperspectral camera and an integrating sphere to carry out radiation correction on the reflected or transmitted spectral image; acquiring a film reflectivity or transmissivity spectrum according to the transmission spectrum without the film or the standard specular reflection spectrum; and determining the number of global interference periods according to a reflectivity or transmissivity curve, and calculating by using a fast Fourier transform method or a spectrum fitting method to obtain the film thickness. Image data with space and spectrum information is acquired through a hyperspectral camera, high-precision film thickness measurement under global imaging and dynamic scanning is realized through an algorithm combining fast Fourier transform and spectrum fitting, and meanwhile, the film thickness measurement precision is improved by adopting dark noise correction and integrating sphere radiation correction. The quantitative accuracy of incident light and sample reflection or transmission light is ensured, and the detection efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hyperspectral imaging, and particularly to a film thickness measurement method and system based on a line-scanning hyperspectral camera. Background Art

[0002] Thin films are widely used in many fields, especially in the semiconductor and optical device fields. With the continuous development of the information industry, the demand for optical thin films is increasing day by day, and at the same time, the requirements for device characteristics are getting higher and higher. Physical thickness is one of the most basic parameters of thin films, which will affect the final performance of the entire device. Therefore, it is of great significance to quickly and accurately measure the thickness of thin films during the production process.

[0003] During the film thickness measurement process, in order to protect the thin film from being damaged, non-contact measurement is usually required. Among many non-contact thin film thickness measurement methods, the spectral method is the most efficient, concise, well-integrated, and has outstanding comprehensive advantages, occupying an important position in the thin film thickness measurement market.

[0004] The spectral method is based on the principle of thin film interference. By transmitting a beam of broad-spectrum light or incident at a certain angle on the surface of the thin film to be measured, the transmitted light or reflected light will interfere, and thus oscillating peaks with enhanced or weakened intensities will be shown at different wavelengths. There is a certain relationship between the period of oscillation and the positions of the peaks and valleys and the thickness of the thin film. By analyzing the transmission spectrum or reflection spectrum, the thickness of the thin film can be obtained. However, most of the current products on the market are single-point thin film tests based on optical probes or multi-point measurements based on the Z-shaped scanning method. This measurement method cannot well measure the complete information of the entire surface of the sample. For thin film products in high-end manufacturing, users often need to obtain the thickness distribution of the entire thin film sample.

[0005] The hyperspectral camera based on the line-scanning imaging method can well meet the requirements of full-width measurement of thin films and is very suitable for thin film samples flowing continuously on the production line. The hyperspectral camera combines line-scanning technology and hyperspectral imaging technology. It can obtain reflection or transmission spectral data at multiple wavelengths during the real-time movement of the thin film, thereby forming a hyperspectral image. The data of each point in the image contains information in the entire spectral range. By analyzing the reflection spectrum or transmission spectrum, the thickness distribution of the thin film sample with the entire width can be obtained. This method has a mature principle, simple hardware implementation, and advantages such as fast measurement and real-time measurement.

[0006] For a solution that measures the reflection spectrum at a certain angle of incidence on the surface of the thin film to be measured and then calculates the thickness of the thin film, at different field-of-view angles of the hyperspectral camera, that is, at different spatial dimensions of the acquired image, there are slight differences in the corresponding reflection angles. This part of the difference will cause relatively large errors when calculating the thickness of the thin film. Therefore, accurately obtaining the incident angle or reflection angle of light at different spatial dimensions is of great significance for improving the measurement accuracy and measurement accuracy. Summary of the Invention

[0007] Based on the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a film thickness measurement method and system based on a line-scanning hyperspectral camera to solve the above technical problems.

[0008] To achieve the above object, the present invention provides the following technical solutions: A film thickness measurement method based on a line-scanning hyperspectral camera, including: Using a line-scanning hyperspectral camera to obtain a reflection or transmission spectral image of a thin film composed of spatial dimensions and spectral dimensions; Obtaining the dark noise image of the hyperspectral camera used and performing denoising processing on the reflection or transmission spectral image; Using the hyperspectral camera and an integrating sphere to perform radiation correction on the reflection or transmission spectral image; Obtaining the reflectance or transmittance spectrum of the thin film according to the transmission spectrum without the thin film or the standard specular reflection spectrum; According to the reflectance or transmittance curve, determining the number of global interference periods. When the number of interference periods is greater than or equal to 5, using the fast Fourier transform method to calculate the film thickness. When the number of interference periods is less than 5, using the spectral fitting method to calculate the film thickness.

[0009] The present invention is further configured such that using the fast Fourier transform method to calculate the film thickness includes: Obtaining reflectance or transmittance data and performing denoising, smoothing, and baseline removal on the data; Using a selection algorithm to select data and using a window function for the selected range to reduce spectral leakage; Determining the corresponding refractive index data according to the selection result and interpolating the refractive index data to match the dimensions of the spectral data; Determining the incident angles corresponding to the spectra in different spatial dimensions according to the field-of-view angle of the lens of the hyperspectral camera and the angle between the camera and the normal of the plane of the thin film to be measured; Performing coordinate transformation on the spectra in different spatial dimensions according to the angle correction algorithm and the selected refractive index data; Performing a fast Fourier transform on the coordinate-transformed spectral data and obtaining the peak positions from the result of the transformation; Using the peak point coordinates as parameters, the fitting peak point data is obtained by Gaussian fitting, and the fitting peak point data is the film thickness.

[0010] The present invention is further configured to calculate the film thickness by using a spectral fitting method, including: Obtaining reflectivity or transmittance data, and performing denoising, smoothing, and baseline removal on the data; According to the field of view angle of the lens of the hyperspectral camera and the angle between the camera and the normal direction of the plane of the thin film to be measured, determining the incident angles corresponding to the spectra in different spatial dimensions; According to the angles in different spatial dimensions, correcting the spectral reflectivity or transmittance formulas in different spatial dimensions; Given an initial value range, using the traversal method and the least squares method to obtain the initial values of the optimal fitting parameters; Using the initial values of the optimal fitting parameters as fitting parameters, obtaining the film thickness by using the reflectivity or transmittance fitting method.

[0011] The present invention also provides a film thickness measurement system based on a line-scanning hyperspectral camera for implementing the above-mentioned film thickness measurement method based on a line-scanning hyperspectral camera. The system includes: an illumination light source module, a thin film, a push-scanning module, a hyperspectral camera imaging module, and a calculation and processing module; the calculation and processing module includes a calculation and processing unit, and the calculation and processing unit is respectively connected to a first communication module and a second communication module. The first communication module is connected to a driving module, the driving module is connected to the push-scanning module, and the second communication module is connected to the hyperspectral camera.

[0012] The present invention is further configured that the line-scanning hyperspectral film thickness measurement system is a reflection-type line-scanning hyperspectral film thickness measurement system, and further includes: an inclination sensor and a third communication module; The calculation and processing unit is connected to the third communication module, and the third communication module is connected to the inclination sensor; The thin film to be measured is placed on the push-scanning module and moves with the push-scanning module to realize the imaging of the entire sample. The calculation and processing module issues an instruction, which is transmitted to the first driving module through the first communication module, and then the first driving module drives the push-scanning module according to the instruction; The hyperspectral camera imaging module and the illumination light source module are located on both sides of the plane where the line-scanning area is located and are installed symmetrically like a mirror, and are used for hyperspectral imaging of the thin film sample. The control of the hyperspectral camera imaging module issues an instruction through the calculation and processing unit, and the instruction is transmitted through the second communication module; The inclination sensor is installed above or below or on the side of the hyperspectral camera imaging module, and is used to monitor the installation angle of the hyperspectral camera, accurately calculate the incident angle of the reflected light, and the angle read by the inclination sensor is communicated with the calculation and processing unit through the third communication module.

[0013] The present invention is further configured such that the illumination light source module is a uniform linear light source for illuminating the thin film to be measured. The size of the uniform linear light source is larger than the width of the thin film to be measured, so as to enable the light for specular reflection on the thin film surface to enter the collection range of the camera field of view angle.

[0014] The present invention is further configured such that the line-scanning hyperspectral film thickness measurement system is a transmissive line-scanning hyperspectral film thickness measurement system; The thin film to be measured is placed on the push-scan module and moves with the push-scan module to realize imaging of the entire sample. The calculation and processing module issues an instruction, which is transmitted through the first communication module to the first driving module, and then the first driving module drives the push-scan module according to the instruction; The hyperspectral camera imaging module is installed perpendicular to the thin film plane for hyperspectral imaging of the thin film sample. The control of the hyperspectral camera issues an instruction through the calculation and processing unit, and the instruction is transmitted through the second communication module; The calculation and processing unit is used for communicating with each module, and processing the acquired hyperspectral image and outputting the result.

[0015] The present invention is further configured such that the illumination light source module is a uniform linear light source for illuminating the thin film to be measured. The size of the uniform linear light source is larger than the width of the thin film, so as to realize full-range illumination in the width direction of the thin film.

[0016] The present invention provides a film thickness measurement method and system based on a line-scanning hyperspectral camera. The method includes: acquiring a reflection or transmission spectral image of a thin film composed of a spatial dimension and a spectral dimension by using a line-scanning hyperspectral camera; acquiring a dark noise image of the used hyperspectral camera and performing denoising processing on the reflection or transmission spectral image; performing radiometric calibration on the reflection or transmission spectral image by using the hyperspectral camera and an integrating sphere; obtaining the reflectance or transmittance spectrum of the thin film according to the transmission spectrum or standard specular reflection spectrum without the thin film; determining the number of global interference periods according to the reflectance or transmittance curve. When the number of interference periods is greater than or equal to 5, the film thickness is calculated by using the fast Fourier transform method. When the number of interference periods is less than 5, the film thickness is calculated by using the spectral fitting method. The beneficial effects generated include: High-precision film thickness measurement: By using a hyperspectral camera to acquire image data with both spatial and spectral information, and through fine processing of the reflection or transmission spectrum, accurate measurement of the thin film thickness is realized. Especially after the system collects data, denoising, smoothing, and baseline removal processing are performed, and then combined with two algorithms of fast Fourier transform and spectral fitting, it not only meets the high-efficiency processing when there are more interference periods, but also can improve the measurement accuracy through fine fitting when the periods are less, ensuring that the system has good measurement robustness and accuracy under different conditions; Global imaging and dynamic scanning: By means of a push-broom module, continuous imaging of the entire thin film sample to be measured is achieved, ensuring that the film thickness distribution of the entire sample can be completely collected and analyzed. This method based on continuous motion scanning not only improves the detection efficiency but also enables real-time dynamic measurement in terms of local feature analysis, facilitating subsequent precise positioning and data processing of each region; Efficient optical and data correction mechanisms: By setting a uniform line light source with a size larger than the width of the thin film to be measured, the entire sample surface can be fully covered to achieve full-range illumination. For the image data obtained by the hyperspectral camera, not only is preliminary noise reduction achieved through the dark noise image, but also radiation correction is realized using an integrating sphere, ensuring the quantitative accuracy of the incident light and the light reflected or transmitted by the sample and improving the reliability in the data processing stage.

[0017] The above description is only an overview of the technical solution of this application. In order to be able to more clearly understand the technical means of this application, it can be implemented in accordance with the content of the specification. And in order to make the above and other purposes, features and advantages of this application more obvious and understandable, the following specifically lists the specific implementation manners of this application. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings: Figure 1 It is a schematic diagram of the thin film interference principle; Figure 2 It is a flowchart of a film thickness measurement method based on a line-scanning hyperspectral camera shown in an exemplary embodiment of the present invention; Figure 3 It is a flowchart of calculating the film thickness using the fast Fourier transform method shown in an exemplary embodiment of the present invention; Figure 4 It is a result diagram of calculating the film thickness by the fast Fourier method shown in an exemplary embodiment of the present invention; Figure 5 It is a flowchart of calculating the film thickness using the spectral fitting method shown in an exemplary embodiment of the present invention; Figure 6 It is an example diagram of calculating the film thickness by the spectral fitting method shown in an exemplary embodiment of the present invention; Figure 7 It is a thickness distribution diagram of the oxide layer on the surface of a wafer shown in an exemplary embodiment of the present invention; Figure 8 It is an incident angle difference diagram shown in an exemplary embodiment of the present invention; Figure 9 Schematic structural diagram of a reflective line-scanning hyperspectral film thickness measurement system shown for an exemplary embodiment of the present invention; Figure 10 Schematic structural diagram of a transmissive line-scanning hyperspectral film thickness measurement system shown for an exemplary embodiment of the present invention. Detailed implementation manners

[0019] The following will describe the implementation manners of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the protection scope of the present invention.

[0020] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0021] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0022] Embodiment 1: First of all, it should be noted that the spectral method for measuring the film thickness is based on the interference principle to measure the film thickness. As Figure 1 shown, taking a single-layer film as an example, a beam of light with a wide wavelength and an intensity of A is incident on the upper surface of the film at an angle of α. According to the law of reflection, part of the light is reflected by the upper surface, denoted as , then there is is the Fresnel reflection coefficient at the boundary when the light travels from the previous medium to the film. The remaining incident light is refracted, and according to Snell's law, its magnitude is t 01A0. This part of the light passes through the thin film and reaches the lower edge of the thin film at an angle β. At this time, a part of the light is reflected. Then, after reaching the upper surface of the thin film, part of the light is reflected back into the thin film by the upper surface, and part of it passes through the upper surface and interferes with the light reflected for the first time. The interference light is collected and analyzed by a hyperspectral imager to obtain an interference image, and a distribution image of the light intensity varying with the wavelength is obtained. Then, the thickness of the measured thin film can be calculated using the interference image.

[0023] Ignoring the absorption of light by the thin film material and considering the interference of all reflected light beams, under multi-beam interference, the reflectivity can be accurately expressed by the optical parameters of each layer of medium, the incident angle α, and the refraction angle β, and other parameters. The specific calculation formula is as follows:

[0024] where n0 is the refractive index of air, n1 is the refractive index of the thin film, n2 is the refractive index of the substrate, r 01 and r 12 are the Fresnel reflection coefficients at the upper surface interface and the lower surface interface of the thin film respectively, R 01 and R 12 are respectively the light intensity ratios of the reflection from the upper surface of the thin film and the reflection from the lower surface of the thin film, d is the thickness of the thin film, and is the optical path difference.

[0025] A film thickness measurement method based on a line-scanning hyperspectral camera, as Figure 2 shown, includes: Using a line-scanning hyperspectral camera to obtain the reflection or transmission spectral image of the thin film composed of the spatial dimension and the spectral dimension; Obtaining the dark noise image of the used hyperspectral camera and performing denoising processing on the reflection or transmission spectral image; Using the hyperspectral camera and an integrating sphere to perform radiometric calibration on the reflection or transmission spectral image; Obtaining the thin film reflectivity or transmittance spectrum according to the transmission spectrum without the thin film or the standard specular reflection spectrum; Determining the number of global interference periods according to the reflectivity or transmittance curve. When the number of interference periods is greater than or equal to 5, the fast Fourier transform method is used to calculate the film thickness. When the number of interference periods is less than 5, the spectral fitting method is used to calculate the film thickness.

[0026] Please refer to Figure 3 , the present invention is further set as using the fast Fourier transform method to calculate the film thickness, including: Obtaining the reflectivity or transmittance data and performing denoising, smoothing, and baseline removal processing on the data; Using the region selection algorithm to perform data region selection and using a window function on the selected region to reduce spectral leakage; Determine the corresponding refractive index data according to the selected area result, and interpolate the refractive index data to match the dimensions of the refractive index data and the spectral data; Determine the incident angles corresponding to the spectra in different spatial dimensions according to the lens field of view angle of the hyperspectral camera and the angle between the camera and the normal of the plane of the thin film to be measured; Perform coordinate transformation on the spectra in different spatial dimensions according to the angle correction algorithm and the refractive index data of the selected area; Perform a fast Fourier transform on the coordinate-transformed spectral data, and obtain the peak positions from the results of the transform; Using the peak position coordinates as parameters, obtain the fitted peak point data by Gaussian fitting, and the fitted peak point data is the film thickness.

[0027] Specific implementation methods and examples: The principle of calculating the film thickness using the fast Fourier transform method is: According to the expression (1) of the reflectivity, it can be known that In order to be able to perform the Fourier transform, this formula can be rewritten as: In this case, let Perform coordinate transformation on the data, then . Perform a Fourier transform on the measured R, obtain the curve corresponding to the position with the highest peak and its nearby positions, and perform Gaussian fitting on these data to obtain the central position corresponding to the fitted peak, which is the thickness value d.

[0028] As Figure 4 shown, Figure 4 is the result diagram of calculating the film thickness by this method, the nominal film thickness is , and the film thickness calculated using the said method is .

[0029] Please refer to Figure 5 , the present invention is further set to calculate the film thickness using the spectral fitting method, including: Obtain the reflectivity or transmittance data, and perform denoising, smoothing and baseline removal processing on the data; Determine the incident angles corresponding to the spectra in different spatial dimensions according to the lens field of view angle of the hyperspectral camera and the angle between the camera and the normal of the plane of the thin film to be measured; Correct the spectral reflectivity or transmittance formula in different spatial dimensions according to the angles in different spatial dimensions; Given an initial value range, use the traversal method and the least squares method to obtain the initial value of the optimal fitting parameter; Using the initial value of the optimal fitting parameter as the fitting parameter, obtain the film thickness using the reflectivity or transmittance fitting method.

[0030] Specific implementation methods and examples: The main principle of calculating film thickness by spectral fitting method is to use the standard reflection or transmission spectral expression. Given an initial value, through the least squares method, continuously adjust the parameters to minimize the difference between the calculated theoretical spectrum and the actual measured spectrum, so as to obtain the optimal fitting parameters. These fitting parameters include the thickness of the thin film. Therefore, we can obtain the thickness value d of the thin film to be measured according to the fitting result.

[0031] This technique depends on the initial parameter values. When the deviation of the given initial parameter values is large, the spectral curve may not be fitted. Therefore, the traversal method is introduced. By continuously changing the initial parameter values, the optimal initial fitting parameter values are obtained, and further using the optimal initial fitting parameter values, the film thickness value d is fitted.

[0032] As Figure 6 shown Figure 6 is an example of calculating film thickness by spectral fitting method. The standard film thickness value is 1000 nm, and the fitted film thickness value is 1001.090 nm.

[0033] Furthermore, by applying this fitting method to different spatial points in the hyperspectral image, the film thickness distribution at different spatial positions of the measured thin film can be obtained. As Figure 7 shown, it is the thickness distribution map of the oxide layer on the surface of the wafer.

[0034] Furthermore, for the hyperspectral line scan mode, the incident angles of the light corresponding to the reflection or transmission spectra of the thin films in different spatial dimensions collected by line scan are not completely consistent. Especially when the field of view angle of the imaging lens used is relatively large, the calculation error caused by the angular difference of the spatial positions is relatively large. Therefore, the angular correction of the spatial positions is particularly important.

[0035] As Figure 8 shown on the left, the main light rays reflected or transmitted at each pixel corresponding spatial position are used to replace all the reflected or transmitted light rays at each spatial position. For the transmission spectrum, the angle of the spatial position is related to the field of view angle of the hyperspectral system. In the case of perpendicular illumination of the light source, the incident angle of the light corresponding to the middle of the spatial dimension of the collected transmission spectrum image is 0°, and from the middle to the edge spatial positions, the incident angle gradually increases from 0° to half of the field of view angle.

[0036] As Figure 8 shown on the right, for the reflection spectrum, the angle of the spatial position is related to the field of view angle of the hyperspectral system and the incident angle of the light source. Assuming that the included angle between the incident light source and the thin film plane is θ and the field of view angle of the hyperspectral system is α, then the incident angle of the light corresponding to the middle of the spatial dimension of the collected reflection spectrum image is θ, and from the middle to the edge spatial positions, the incident angle gradually increases from θ to In this case, when the field of view angle is relatively large, the incident angle corresponding to the edge position will be much larger than that at the middle position. Therefore, the correction of the formula is particularly important.

[0037] Embodiment 2: An exemplary film thickness measurement system based on a line-scanning hyperspectral camera is used to implement the above-mentioned film thickness measurement method based on a line-scanning hyperspectral camera. The system includes: an illumination light source module, a thin film, a push-broom module, a hyperspectral camera imaging module, and a calculation and processing module; the calculation and processing module includes a calculation and processing unit, and the calculation and processing unit is respectively connected to a first communication module and a second communication module. The first communication module is connected to a driving module, the driving module is connected to the push-broom module, and the second communication module is connected to the hyperspectral camera.

[0038] As Figure 9 shown, the present invention is further configured such that the line-scanning hyperspectral film thickness measurement system is a reflection-type line-scanning hyperspectral film thickness measurement system, and further includes: an inclination sensor and a third communication module; The calculation and processing unit is connected to the third communication module, and the third communication module is connected to the inclination sensor; The thin film to be measured is placed on the push-broom module and moves with the push-broom module to achieve imaging of the entire sample. The calculation and processing module issues an instruction, which is transmitted to the first driving module through the first communication module, and then the first driving module drives the push-broom module according to the instruction; The hyperspectral camera imaging module and the illumination light source module are located on both sides of the plane where the line-scanning area is located and are symmetrically installed in a mirror image for performing hyperspectral imaging on the thin film sample. The control of the hyperspectral camera imaging module issues an instruction through the calculation and processing unit, and the instruction is transmitted through the second communication module; The inclination sensor is installed above or below or on the side of the hyperspectral camera imaging module for monitoring the installation angle of the hyperspectral camera, accurately calculating the incident angle of the reflected light, and the angle read by the inclination sensor is communicated with the calculation and processing unit through the third communication module.

[0039] The present invention is further configured such that the illumination light source module is a uniform line light source for illuminating the thin film to be measured. The size of the uniform line light source is larger than the width of the thin film to be measured to enable the light reflected specularly on the surface of the thin film to enter the collection range of the camera's field of view angle.

[0040] As Figure 10 shown, the present invention is further configured such that the line-scanning hyperspectral film thickness measurement system is a transmission-type line-scanning hyperspectral film thickness measurement system; The thin film to be measured is placed on the push-broom module and moves with the push-broom module to achieve imaging of the entire sample. The calculation and processing module issues an instruction, which is transmitted to the first driving module through the first communication module, and then the first driving module drives the push-broom module according to the instruction; The hyperspectral camera imaging module is installed perpendicular to the film plane and is used to perform hyperspectral imaging on the film sample. The control of the hyperspectral camera is issued by the calculation and processing unit and the command is transmitted through the second communication module. The calculation and processing unit is used to communicate with each module, and process and output the collected hyperspectral images.

[0041] The present invention is further configured such that the illumination light source module is a uniform linear light source for illuminating the film to be measured. The size of the uniform linear light source is larger than the width of the film, so as to achieve full-range illumination in the width direction of the film.

[0042] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wire (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access or a data storage device such as a server or data center that contains one or more collections of available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0043] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Among them, A and B can be singular or plural. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after, but it may also represent an "and / or" relationship, which can be specifically understood with reference to the context before and after.

[0044] In this application, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or a similar expression means any combination of these items, including any combination of single item(s) or plural item(s). For example, at least one of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, and c can be single or multiple.

[0045] It should be understood that in various embodiments of this application, the magnitudes of the sequence numbers of the above - mentioned processes do not mean the sequence of execution. The execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0046] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professionals can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0047] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0048] In several embodiments provided in this application, it should be understood that the disclosed systems can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0049] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0050] In addition, in each embodiment of the present application, each functional unit may be integrated into one processing unit, may exist separately physically for each unit, or two or more units may be integrated into one unit.

[0051] If the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0052] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A film thickness measurement method based on a line-scanning hyperspectral camera, characterized in that, Comprising: Obtaining a reflection or transmission spectral image of a thin film composed of a spatial dimension and a spectral dimension using a line-scanning hyperspectral camera; Obtaining a dark noise image of the used hyperspectral camera and performing denoising processing on the reflection or transmission spectral image; Performing radiometric calibration on the reflection or transmission spectral image using the hyperspectral camera and an integrating sphere; Obtaining the reflectance or transmittance spectrum of the thin film according to the transmission spectrum without the thin film or the standard specular reflection spectrum; Determining the number of global interference periods according to the reflectance or transmittance curve. When the number of interference periods is greater than or equal to 5, the film thickness is calculated using the fast Fourier transform method. When the number of interference periods is less than 5, the film thickness is calculated using the spectral fitting method.

2. The film thickness measurement method based on a line-scanning hyperspectral camera according to claim 1, wherein Calculating the film thickness using the fast Fourier transform method, including: Obtaining reflectance or transmittance data and performing denoising, smoothing, and baseline removal on the data; Using a selection algorithm to select data regions and applying a window function to the selected region to reduce spectral leakage; Determining the corresponding refractive index data according to the selection result and interpolating the refractive index data to match the dimensions of the spectral data; Determining the incident angles corresponding to the spectra in different spatial dimensions according to the field of view angle of the lens of the hyperspectral camera and the angle between the camera and the normal of the plane of the thin film to be measured; Performing coordinate transformation on the spectra in different spatial dimensions according to the angle correction algorithm and the selected region refractive index data; Performing a fast Fourier transform on the coordinate-transformed spectral data and obtaining the peak positions from the transformation result; Using the peak position coordinates as parameters and obtaining the fitted peak point data by Gaussian fitting. The fitted peak point data is the film thickness.

3. The film thickness measurement method based on a line-scanning hyperspectral camera according to claim 1, wherein Calculating the film thickness using the spectral fitting method, including: Obtaining reflectance or transmittance data and performing denoising, smoothing, and baseline removal on the data; Determining the incident angles corresponding to the spectra in different spatial dimensions according to the field of view angle of the lens of the hyperspectral camera and the angle between the camera and the normal of the plane of the thin film to be measured; Correcting the spectral reflectance or transmittance formula in different spatial dimensions according to the angles in different spatial dimensions; Given an initial value range, using the traversal method and the least squares method to obtain the initial values of the optimal fitting parameters; Using the initial values of the optimal fitting parameters as the fitting parameters and obtaining the thin film thickness using the reflectance or transmittance fitting method.

4. A film thickness measurement system based on a line-scanning hyperspectral camera, which is used to implement a film thickness measurement method based on a line-scanning hyperspectral camera according to any one of claims 1-3, characterized in that, Comprising: An illumination light source module, a thin film, a push-broom module, a hyperspectral camera imaging module, and a calculation and processing module; The calculation and processing module includes a calculation and processing unit. The calculation and processing unit is respectively connected to a first communication module and a second communication module. The first communication module is connected to a driving module, the driving module is connected to the push-broom module, and the second communication module is connected to the hyperspectral camera.

5. The film thickness measurement system based on a line-scanning hyperspectral camera according to claim 4, wherein The line-scanning hyperspectral film thickness measurement system is a reflection-type line-scanning hyperspectral film thickness measurement system, and further includes: an inclination sensor and a third communication module; The calculation and processing unit is connected to the third communication module, and the third communication module is connected to the inclination sensor; The thin film to be measured is placed on the push-broom module and moves with the push-broom module to achieve imaging of the entire sample. The calculation and processing module issues an instruction, which is transmitted to the first driving module through the first communication module, and then the first driving module drives the push-broom module according to the instruction; The hyperspectral camera imaging module and the illumination light source module are located on both sides of the plane where the line scan area is located, and are installed symmetrically like a mirror, and are used for hyperspectral imaging of the thin film sample. The control of the hyperspectral camera imaging module issues commands through the calculation and processing unit, and the commands are transmitted through the second communication module; The inclination sensor is installed above or below or on the side of the hyperspectral camera imaging module, and is used to monitor the installation angle of the hyperspectral camera, accurately calculate the incident angle of the reflected light, and the angle read by the inclination sensor communicates with the calculation and processing unit through the third communication module.

6. The film thickness measurement system based on a line-scanning hyperspectral camera according to claim 5, wherein, The illumination light source module is a uniform line light source, which is used to illuminate the thin film to be measured. The size of the uniform line light source is larger than the width of the thin film to be measured, and is used to enable the light reflected specularly on the surface of the thin film to enter the collection range of the camera's field of view angle.

7. A film thickness measurement system based on a line-scanning hyperspectral camera according to claim 4, characterized in that, The line scan hyperspectral film thickness measurement system is a transmission type line scan hyperspectral film thickness measurement system; The thin film to be measured is placed on the push-scan module and moves with the push-scan module to realize the imaging of the entire sample. The calculation and processing module issues commands, which are transmitted to the first drive module through the first communication module, and then the first drive module drives the push-scan module according to the commands; The hyperspectral camera imaging module is installed perpendicular to the thin film plane and is used for hyperspectral imaging of the thin film sample. The control of the hyperspectral camera issues commands through the calculation and processing unit, and the commands are transmitted through the second communication module; The calculation and processing unit is used to communicate with each module, and process the collected hyperspectral images and output the results.

8. A film thickness measurement system based on a line-scanning hyperspectral camera according to claim 7, characterized in that, The illumination light source module is a uniform line light source, which is used to illuminate the thin film to be measured. The size of the uniform line light source is larger than the width of the thin film, and is used to realize full-range illumination in the width direction of the thin film.

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