A film thickness measurement method and system based on line scanning hyperspectral camera

Abstract

The present invention discloses a film thickness measurement method and system based on a line-scanning hyperspectral camera, which relates to the field of hyperspectral imaging technology. The method includes: obtaining a reflection or transmission spectrum image and a dark noise image, and performing denoising processing; using a hyperspectral camera and an integrating sphere to perform radiation correction on the reflection or transmission spectrum image; obtaining a film reflectivity or transmittance spectrum based on the transmission spectrum in the absence of a thin film or a standard mirror reflection spectrum; determining the number of global interference cycles based on the reflectivity or transmittance curve, and calculating the film thickness using a fast Fourier transform method or a spectral fitting method. The hyperspectral camera is used to obtain image data with spatial and spectral information, and an algorithm combining fast Fourier transform and spectral fitting is used to achieve high-precision film thickness measurement under global imaging and dynamic scanning. At the same time, dark noise correction and integrating sphere radiation correction are used to ensure the quantitative accuracy of the incident light and the sample reflected or transmitted light, greatly improving the detection efficiency.

Description

Technical Field

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

[0002] Thin films are widely used in numerous fields, particularly semiconductors and optical devices. With the continuous development of the information industry, the demand for optical thin films is increasing, and the requirements for device properties are also becoming increasingly stringent. Physical thickness is one of the most fundamental parameters of thin films, as it affects the ultimate performance of the entire device. Therefore, rapid and accurate measurement of film thickness is of great significance during the production process.

[0003] During film thickness measurement, non-contact measurement is often required to protect the film from damage. Among the numerous non-contact film thickness measurement methods, spectroscopy holds a significant position in the film thickness measurement market due to its efficiency, simplicity, integration, and comprehensive advantages.

[0004] Spectroscopy is based on the principle of thin film interference. By transmitting a beam of light with a wide spectrum or incident at a certain angle on the surface of the film being measured, the transmitted or reflected light will interfere, resulting in oscillation peaks with increasing or decreasing intensity at different wavelengths. There is a certain relationship between the period of oscillation and the position of the peaks and valleys and the thickness of the film. By analyzing the transmission spectrum or reflection spectrum, the thickness of the film can be obtained. However, most products currently on the market are based on single-point thin film testing using optical probes, or multi-point measurements using Z-scanning. This measurement method cannot measure complete information on the entire surface of the sample. For thin film products in high-end manufacturing, users often need to be able to obtain the thickness distribution of the entire film sample.

[0005] Hyperspectral cameras based on line scanning imaging can effectively meet the needs of full-width thin film measurement and are ideally suited for thin film samples that continuously flow on production lines. Combining line scanning and hyperspectral imaging technologies, hyperspectral cameras can acquire reflection or transmission spectral data at multiple wavelengths while the film is moving in real time, forming a hyperspectral image. The data at each point in the image contains information across the entire spectral range. By analyzing the reflection or transmission spectrum, the thickness distribution of the entire film sample width can be determined. This method is well-established in principle, simple to implement in hardware, and offers the advantages of fast and real-time measurement.

[0006] For the solution of calculating film thickness by incident light at a certain angle on the surface of the film being measured and then measuring the reflection spectrum, there are slight differences in the corresponding reflection angles at different field angles of view of the hyperspectral camera, that is, at different spatial dimensions of the captured image. These differences can cause large errors in the film thickness calculation. Therefore, accurately obtaining the incident or reflection angle of light in different spatial dimensions is of great significance for improving measurement precision and accuracy. Summary of the Invention

[0007] Based on the above-mentioned shortcomings 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-mentioned technical problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a film thickness measurement method based on a line scanning hyperspectral camera, comprising:

[0009] Use a line scanning hyperspectral camera to obtain a reflection or transmission spectrum image of the film consisting of spatial and spectral dimensions;

[0010] Acquire a dark noise image of the hyperspectral camera used, and perform denoising processing on the reflection or transmission spectrum image;

[0011] Using the hyperspectral camera and integrating sphere, performing radiation correction on the reflection or transmission spectrum image;

[0012] Obtaining the reflectivity or transmittance spectrum of the thin film according to the transmittance spectrum without the thin film or the standard mirror reflectance spectrum;

[0013] According to the reflectivity or transmittance curve, the number of global interference periods is determined. 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 spectrum fitting method.

[0014] The present invention is further configured to calculate the film thickness using a fast Fourier transform method, including:

[0015] Obtain reflectance or transmittance data and perform denoising, smoothing and baseline removal on the data;

[0016] Use the selection algorithm to select data areas, and use the window function on the selection range to reduce spectrum leakage;

[0017] Determine the corresponding refractive index data based on the selection result, and interpolate the refractive index data to match the dimensions of the refractive index data and the spectral data;

[0018] Determining the incident angle corresponding to spectra of different spatial dimensions based on the field of view of the hyperspectral camera and the angle between the camera and the normal of the film plane to be measured;

[0019] According to the angle correction algorithm and the selected area refractive index data, the coordinate transformation of the spectra in different spatial dimensions is performed;

[0020] Perform fast Fourier transform on the spectral data after coordinate transformation, and obtain the peak point from the transformation result;

[0021] The peak point coordinates are used as parameters and Gaussian fitting is used to obtain the fitted peak point data, which is the film thickness.

[0022] The present invention is further configured to calculate the film thickness using a spectrum fitting method, comprising:

[0023] Obtain reflectance or transmittance data and perform denoising, smoothing and baseline removal on the data;

[0024] Determining the incident angle corresponding to spectra of different spatial dimensions based on the field of view of the hyperspectral camera and the angle between the camera and the normal of the film plane to be measured;

[0025] According to the angles of different spatial dimensions, the spectral reflectance or transmittance formulas of different spatial dimensions are modified;

[0026] Given an initial value range, use the ergodic method and the least squares method to obtain the optimal initial value of the fitting parameter;

[0027] The initial values ​​of the optimal fitting parameters are used as fitting parameters, and the film thickness is obtained using the reflectivity or transmittance fitting method.

[0028] The present invention also provides a film thickness measurement system based on a line scanning hyperspectral camera, which 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 film, a push-scan module, a hyperspectral camera imaging module and a calculation and processing module; the calculation and processing module includes a calculation processing unit, which is connected to a first communication module and a second communication module respectively, the first communication module is connected to a driving module, the driving module is connected to the push-scan module, and the second communication module is connected to the hyperspectral camera.

[0029] The present invention is further configured such that the line scanning hyperspectral film thickness measurement system is a reflective line scanning hyperspectral film thickness measurement system, further comprising: a tilt sensor and a third communication module;

[0030] The calculation processing unit is connected to the third communication module, and the third communication module is connected to the tilt sensor;

[0031] The film to be tested is placed on the push-scan module and moves with the push-scan module to achieve imaging of the entire sample. The calculation and processing module issues instructions, which are transmitted to the first driving module through the first communication module. The first driving module then drives the push-scan module according to the instructions.

[0032] 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 in a mirror-symmetrical manner. They are used to perform hyperspectral imaging of thin film samples. The control of the hyperspectral camera imaging module is carried out by issuing instructions through the computing processing unit and transmitting the instructions through the second communication module.

[0033] The tilt sensor is installed above, below or on the side of the hyperspectral camera imaging module to monitor the installation angle of the hyperspectral camera and accurately calculate the incident angle of the reflected light. The angle read by the tilt sensor is communicated with the computing processing unit through the third communication module.

[0034] The present invention is further configured such that the illumination light source module is a uniform line light source for illuminating the film to be measured. The size of the uniform line light source is larger than the width of the film to be measured, and is used to enable the light reflected by the mirror on the surface of the film to enter the camera field of view angle collection range.

[0035] The present invention is further configured such that the line scanning hyperspectral film thickness measurement system is a transmission line scanning hyperspectral film thickness measurement system;

[0036] The film to be tested is placed on the push-scan module and moves with the push-scan module to achieve imaging of the entire sample. The calculation and processing module issues instructions, which are transmitted to the first driving module through the first communication module. The first driving module then drives the push-scan module according to the instructions.

[0037] The hyperspectral camera imaging module is installed perpendicular to the film plane and is used to perform hyperspectral imaging of the film sample. The hyperspectral camera is controlled by issuing instructions through the computing processing unit and the instructions are transmitted through the second communication module.

[0038] The computing and processing unit is used to communicate with each module and process the collected hyperspectral images and output the results.

[0039] The present invention is further configured such that the illumination light source module is a uniform line light source for illuminating the film to be tested. The size of the uniform line light source is larger than the width of the film, and is used to achieve full-range illumination in the width direction of the film.

[0040] The present invention provides a film thickness measurement method and system based on a line scanning hyperspectral camera. The method uses a line scanning hyperspectral camera to obtain a reflection or transmission spectrum image of a thin film consisting of spatial dimensions and spectral dimensions; obtains a dark noise image of the hyperspectral camera used, and performs denoising on the reflection or transmission spectrum image; uses the hyperspectral camera and an integrating sphere to perform radiation correction on the reflection or transmission spectrum image; obtains a film reflectivity or transmittance spectrum based on a transmission spectrum without a thin film or a standard mirror reflection spectrum; determines the number of global interference periods based on a reflectivity or transmittance curve; when the number of interference periods is greater than or equal to 5, uses a fast Fourier transform method to calculate the film thickness; when the number of interference periods is less than 5, uses a spectral fitting method to calculate the film thickness. The beneficial effects produced include:

[0041] High-precision film thickness measurement: Using a hyperspectral camera to acquire image data containing both spatial and spectral information, and by finely processing the reflection or transmission spectra, accurate thin film thickness measurement is achieved. Specifically, after the system acquires data, it performs denoising, smoothing, and baseline removal, and then combines fast Fourier transform and spectral fitting algorithms. This not only satisfies the high-efficiency processing requirements when there are many interference cycles, but also improves measurement accuracy through fine fitting when there are fewer cycles, ensuring the system's robustness and accuracy under various conditions.

[0042] Global imaging and dynamic scanning: The push-scan module continuously images the entire thin film sample to be tested, ensuring that the film thickness distribution of the entire sample can be fully collected and analyzed. This method based on continuous motion scanning not only improves detection efficiency, but also enables real-time dynamic measurement of local feature analysis, facilitating subsequent precise positioning and data processing of each area.

[0043] Efficient optical and data correction mechanisms: A uniform line light source, larger than the width of the film being measured, fully covers the entire sample surface, achieving full-range illumination. Image data captured by the hyperspectral camera is not only initially de-noised using dark noise images, but also radiometrically corrected using an integrating sphere. This ensures quantitative accuracy of incident light and light reflected or transmitted from the sample, improving reliability during data processing.

[0044] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. In the drawings:

[0046] Figure 1 Schematic diagram of thin film interference principle;

[0047] Figure 2 This is a flow chart of a film thickness measurement method based on a line scanning hyperspectral camera according to an exemplary embodiment of the present invention;

[0048] Figure 3 A flowchart showing the use of a fast Fourier transform method to calculate the film thickness according to an exemplary embodiment of the present invention;

[0049] Figure 4 A diagram showing the film thickness calculation results using the fast Fourier transform method according to an exemplary embodiment of the present invention;

[0050] Figure 5 A flow chart showing the use of a spectrum fitting method to calculate film thickness according to an exemplary embodiment of the present invention;

[0051] Figure 6 An example diagram of calculating film thickness using a spectrum fitting method according to an exemplary embodiment of the present invention is shown;

[0052] Figure 7 A diagram showing the thickness distribution of the oxide layer on the surface of a wafer according to an exemplary embodiment of the present invention;

[0053] Figure 8 FIG. 1 is a diagram showing a difference in incident angles according to an exemplary embodiment of the present invention;

[0054] Figure 9 This is a schematic structural diagram of a reflective line scanning hyperspectral film thickness measurement system according to an exemplary embodiment of the present invention;

[0055] Figure 10 The figure is a schematic structural diagram of a transmission-type line scanning hyperspectral film thickness measurement system according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0057] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0058] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the embodiments of the present invention.

[0059] Example 1: First of all, it should be noted that the spectral method for measuring film thickness is based on the interference principle. Figure 1 As shown, taking a single-layer film as an example, a beam of light with a wide wavelength and intensity A is incident on the upper surface of the film at an angle α. According to the law of reflection, part of the light is reflected by the upper surface, which is set as , then is the Fresnel reflection coefficient at the boundary when light passes from the front medium to the film. The rest of the incident light is refracted, and according to Snell's law, its magnitude is t 01 A0. This portion of light passes through the film and reaches the bottom edge of the film at an angle β. At this point, some of the light is reflected. After reaching the top surface of the film, some of the light is reflected back into the film, while some of it passes through the top surface, interfering with the first reflected light. A hyperspectral imager collects and analyzes the interference light to generate an interference image, which shows the distribution of light intensity as it varies with wavelength. This interference image can then be used to calculate the thickness of the film being measured.

[0060] Ignoring the absorption of light by the thin film material and considering the interference of all reflected beams, the reflectivity under multi-beam interference can be determined by the optical parameters of each layer of the medium, the incident angle α and the refraction angle β. The parameters are accurately expressed, and the specific calculation formula is as follows:

[0061] Where n0 is the refractive index of air, n1 is the refractive index of the film, n2 is the refractive index of the substrate, and r 01 and r 12 are the Fresnel reflection coefficients at the upper and lower surfaces of the film, R 01 and R 12 are the ratio of the light intensity reflected from the upper surface of the film to the light intensity reflected from the lower surface of the film, d is the thickness of the film, is the optical path difference.

[0062] A film thickness measurement method based on a line scanning hyperspectral camera, such as Figure 2 Shown, including:

[0063] Use a line scanning hyperspectral camera to obtain a reflection or transmission spectrum image of the film consisting of spatial and spectral dimensions;

[0064] Acquire a dark noise image of the hyperspectral camera used, and perform denoising processing on the reflection or transmission spectrum image;

[0065] Using the hyperspectral camera and integrating sphere, performing radiation correction on the reflection or transmission spectrum image;

[0066] Obtaining the reflectivity or transmittance spectrum of the thin film according to the transmittance spectrum without the thin film or the standard mirror reflectance spectrum;

[0067] According to the reflectivity or transmittance curve, the number of global interference periods is determined. 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 spectrum fitting method.

[0068] See also Figure 3 The present invention is further configured to calculate the film thickness using a fast Fourier transform method, including:

[0069] Obtain reflectance or transmittance data and perform denoising, smoothing and baseline removal on the data;

[0070] Use the selection algorithm to select data areas, and use the window function on the selection range to reduce spectrum leakage;

[0071] Determine the corresponding refractive index data based on the selection result, and interpolate the refractive index data to match the dimensions of the refractive index data and the spectral data;

[0072] Determining the incident angle corresponding to spectra of different spatial dimensions based on the field of view of the hyperspectral camera and the angle between the camera and the normal of the film plane to be measured;

[0073] According to the angle correction algorithm and the selected area refractive index data, the coordinate transformation of the spectra in different spatial dimensions is performed;

[0074] Perform fast Fourier transform on the spectral data after coordinate transformation, and obtain the peak point from the transformation result;

[0075] The peak point coordinates are used as parameters and Gaussian fitting is used to obtain the fitted peak point data, which is the film thickness.

[0076] Specific implementation methods and examples:

[0077] The principle of calculating film thickness using the fast Fourier transform method is:

[0078] According to the reflectivity expression (1), we know that In order to perform Fourier transform, the formula can be rewritten as:

[0079] In this case, Perform coordinate transformation on the data, then Performing Fourier transform on the measured R can obtain the curve corresponding to the highest peak position and its nearby positions. Performing Gaussian fitting on these data can obtain the center position corresponding to the fitted peak, which is the thickness value d.

[0080] like Figure 4 As shown, Figure 4 This is the film thickness calculation result diagram of this method. The nominal film thickness is , the film thickness is calculated using the method .

[0081] See also Figure 5 The present invention is further configured to calculate the film thickness using a spectrum fitting method, including:

[0082] Obtain reflectance or transmittance data and perform denoising, smoothing and baseline removal on the data;

[0083] Determining the incident angle corresponding to spectra of different spatial dimensions based on the field of view of the hyperspectral camera and the angle between the camera and the normal of the film plane to be measured;

[0084] According to the angles of different spatial dimensions, the spectral reflectance or transmittance formulas of different spatial dimensions are modified;

[0085] Given an initial value range, use the ergodic method and the least squares method to obtain the optimal initial value of the fitting parameter;

[0086] The initial values ​​of the optimal fitting parameters are used as fitting parameters, and the film thickness is obtained using the reflectivity or transmittance fitting method.

[0087] Specific implementation methods and examples:

[0088] The main principle of the spectral fitting method for calculating film thickness is to use the standard reflection or transmission spectrum expression. Under given initial values, the least squares method is used to continuously adjust the parameters to minimize the difference between the calculated theoretical spectrum and the actual measured spectrum, thereby obtaining the optimal fitting parameters. These fitting parameters include the thickness of the film. Therefore, we can obtain the film thickness value d that we need to measure based on the fitting results.

[0089] This technique relies on initial parameter values. If the given initial parameter values ​​deviate significantly, the spectral curve may not fit. Therefore, the ergodic method is introduced to obtain the optimal initial fitting parameter values ​​by continuously changing the initial parameter values. The optimal initial fitting parameter values ​​are then used to fit the film thickness d.

[0090] like Figure 6 As shown, Figure 6 This is an example of calculating film thickness using the spectrum fitting method. The standard film thickness is 1000nm, and the film thickness obtained by fitting is 1001.090nm.

[0091] 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 film can be obtained. Figure 7 As shown, it is the thickness distribution of the oxide layer on the surface of the wafer.

[0092] Furthermore, for the hyperspectral line scanning method, the reflection or transmission spectra of thin films of different spatial dimensions collected by line scanning have corresponding incident angles of light that are not completely consistent. Especially when the field of view of the imaging lens used is relatively large, the calculation error caused by the angle difference in spatial position will be relatively large. Therefore, angle correction for spatial position is particularly important.

[0093] like Figure 8 As shown on the left, the principal ray reflected or transmitted at each pixel's corresponding spatial position replaces all reflected or transmitted rays at each spatial position. For the transmission spectrum, the angle of the spatial position is related to the field of view of the hyperspectral system. When the light source is vertical, the incident angle of the light corresponding to the center of the spatial dimension of the collected transmission spectrum image is 0°. From the center to the edge of the spatial position, the incident angle gradually increases from 0° to half the field of view.

[0094] like Figure 8 As 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 angle between the light source and the film plane is θ and the field of view angle of the hyperspectral system is α, the incident angle of the light corresponding to the center of the spatial dimension of the collected reflection spectrum image is θ, and the incident angle gradually increases from θ to α from the center to the edge of the spatial position. In this case, when the field of view is large, the incident angle at the edge will be much larger than that at the center. Therefore, the correction of the formula is particularly important.

[0095] Example 2: This 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 film, a push-scan module, a hyperspectral camera imaging module and a calculation and processing module; the calculation and processing module includes a calculation processing unit, which is connected to the first communication module and the second communication module respectively, the first communication module is connected to the driving module, the driving module is connected to the push-scan module, and the second communication module is connected to the hyperspectral camera.

[0096] like Figure 9 As shown, the present invention is further configured such that the line scanning hyperspectral film thickness measurement system is a reflective line scanning hyperspectral film thickness measurement system, further comprising: a tilt sensor and a third communication module;

[0097] The calculation processing unit is connected to the third communication module, and the third communication module is connected to the tilt sensor;

[0098] The film to be tested is placed on the push-scan module and moves with the push-scan module to achieve imaging of the entire sample. The calculation and processing module issues instructions, which are transmitted to the first driving module through the first communication module. The first driving module then drives the push-scan module according to the instructions.

[0099] 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 in a mirror-symmetrical manner. They are used to perform hyperspectral imaging of thin film samples. The control of the hyperspectral camera imaging module is carried out by issuing instructions through the computing processing unit and transmitting the instructions through the second communication module.

[0100] The tilt sensor is installed above, below or on the side of the hyperspectral camera imaging module to monitor the installation angle of the hyperspectral camera and accurately calculate the incident angle of the reflected light. The angle read by the tilt sensor is communicated with the computing processing unit through the third communication module.

[0101] The present invention is further configured such that the illumination light source module is a uniform line light source for illuminating the film to be measured. The size of the uniform line light source is larger than the width of the film to be measured, and is used to enable the light reflected by the mirror on the surface of the film to enter the camera field of view angle collection range.

[0102] like Figure 10 As shown, the present invention is further configured such that the line scanning hyperspectral film thickness measurement system is a transmission line scanning hyperspectral film thickness measurement system;

[0103] The film to be tested is placed on the push-scan module and moves with the push-scan module to achieve imaging of the entire sample. The calculation and processing module issues instructions, which are transmitted to the first driving module through the first communication module. The first driving module then drives the push-scan module according to the instructions.

[0104] The hyperspectral camera imaging module is installed perpendicular to the film plane and is used to perform hyperspectral imaging of the film sample. The hyperspectral camera is controlled by issuing instructions through the computing processing unit and the instructions are transmitted through the second communication module.

[0105] The computing and processing unit is used to communicate with each module and process the collected hyperspectral images and output the results.

[0106] The present invention is further configured such that the illumination light source module is a uniform line light source for illuminating the film to be tested. The size of the uniform line light source is larger than the width of the film, and is used to achieve full-range illumination in the width direction of the film.

[0107] 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 program are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. 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 via a wired (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0108] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. A and B can be singular or plural. Furthermore, the character " / " as used herein generally indicates an "or" relationship between the associated objects, but it may also indicate an "and / or" relationship. For specific understanding, please refer to the context.

[0109] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0110] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0111] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0112] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0113] In the several embodiments provided in this application, it should be understood that the disclosed system can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as 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 mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0114] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0115] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0116] If the 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 this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the 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 enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0117] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A film thickness measurement method based on a line scanning hyperspectral camera, characterized in that: include: Use a line scanning hyperspectral camera to obtain a reflection or transmission spectrum image of the film consisting of spatial and spectral dimensions; Acquire a dark noise image of the hyperspectral camera used, and perform denoising processing on the reflection or transmission spectrum image; Using the hyperspectral camera and integrating sphere, performing radiation correction on the reflection or transmission spectrum image; Obtaining the reflectivity or transmittance spectrum of the thin film according to the transmittance spectrum without the thin film or the standard mirror reflectance spectrum; According to the reflectivity or transmittance curve, the number of global interference periods is determined. 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 spectrum fitting method. The method of calculating the film thickness using the fast Fourier transform method includes: obtaining reflectivity or transmittance data, and performing denoising, smoothing and baseline removal on the data; selecting the data using a selection algorithm, and applying a window function to the selection range to reduce spectrum leakage; determining the corresponding refractive index data based on the selection result, and interpolating the refractive index data to match the dimensions of the refractive index data and the spectral data; determining the incident angle corresponding to the spectra of different spatial dimensions based on the field of view of the lens of the hyperspectral camera and the angle between the camera and the normal of the plane of the film to be measured; performing coordinate transformation on the spectra of different spatial dimensions based on the angle correction algorithm and the selected refractive index data; performing fast Fourier transform on the spectral data after the coordinate transformation, and obtaining the peak point from the transformation result; using the peak point coordinate as a parameter, obtaining fitting peak point data using Gaussian fitting, and the fitting peak point data is the film thickness.

2. The film thickness measurement method based on a line scanning hyperspectral camera according to claim 1, characterized in that: The film thickness is calculated using a spectrum fitting method, including: Obtain reflectance or transmittance data and perform denoising, smoothing and baseline removal on the data; Determining the incident angle corresponding to spectra of different spatial dimensions based on the field of view of the hyperspectral camera and the angle between the camera and the normal of the film plane to be measured; According to the angles of different spatial dimensions, the spectral reflectance or transmittance formulas of different spatial dimensions are modified; Given an initial value range, use the ergodic method and the least squares method to obtain the optimal initial value of the fitting parameter; The initial values ​​of the optimal fitting parameters are used as fitting parameters, and the film thickness is obtained using the reflectivity or transmittance fitting method.

3. A film thickness measurement system based on a line scanning hyperspectral camera, used to implement the film thickness measurement method based on a line scanning hyperspectral camera according to any one of claims 1-2, characterized in that: include: Illumination light source module, film, push-scan module, hyperspectral camera imaging module, computing and processing module, tilt sensor and third communication module; The calculation processing module includes a calculation processing unit, the calculation processing unit is connected to the first communication module and the second communication module respectively, the first communication module is connected to the driving module, the driving module is connected to the push-broom module, and the second communication module is connected to the hyperspectral camera; The calculation processing unit is connected to the third communication module, and the third communication module is connected to the tilt sensor; The tilt sensor is installed above, below or on the side of the hyperspectral camera imaging module to monitor the installation angle of the hyperspectral camera and accurately calculate the incident angle of the reflected light. The angle read by the tilt sensor is communicated with the computing processing unit through the third communication module.

4. The film thickness measurement system based on a line scanning hyperspectral camera according to claim 3, characterized in that: The line scanning hyperspectral film thickness measurement system is a reflective line scanning hyperspectral film thickness measurement system; The film to be tested is placed on the push-scan module and moves with the push-scan module to achieve imaging of the entire sample. The calculation and processing module issues instructions, which are transmitted to the first driving module through the first communication module. The first driving module then drives the push-scan module according to the instructions. 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 in a mirror-symmetrical manner. They are used to perform hyperspectral imaging of thin film samples. The control of the hyperspectral camera imaging module is achieved by issuing instructions through the computing processing unit, and the instructions are transmitted through the second communication module.

5. The film thickness measurement system based on a line scanning hyperspectral camera according to claim 4, characterized in that: The illumination light source module is a uniform line light source, which is used to illuminate the film to be tested. The size of the uniform line light source is larger than the width of the film to be tested, and is used to enable the light reflected by the mirror on the surface of the film to enter the camera's field of view collection range.

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