Parameter measurement method and related equipment

Abstract

The embodiment of the invention discloses a parameter measurement method and related equipment, which are used for improving the calculation precision of parameters such as sound velocity and Young modulus of a transparent film layer. The method comprises the steps that a target actual measurement signal of a target film layer in a sample is obtained, the target actual measurement signal is a signal returned by a measurement device for measuring the target film layer of the sample, and the sample comprises a plurality of film layers; constructing a fitting function comprising a plurality of elementary functions, the fitting function comprising a plurality of unknown coefficients, the plurality of elementary functions at least comprising a trigonometric function, the unknown coefficients comprising a frequency coefficient of the trigonometric function, and the fitting function being used for representing a reflectivity variation of a target film layer of a measurement sample of the measurement device; fitting the fitting function and the target actual measurement signal under the condition that the values of the plurality of unknown coefficients are not completely the same, and obtaining the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency; and calculating film layer parameters of the target film layer based on the target angular frequency.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of photoacoustic measurement, and particularly to a parameter measurement method and related devices. Background Art

[0002] In the semiconductor field, the photoacoustic effect principle is widely used to measure a series of film layer parameters such as the sound velocity and Young's modulus of a dielectric film.

[0003] In the prior art, for the sound velocity measurement of a transparent film layer in a sample, methods such as window Fourier transform are usually used to convert the detected time-domain oscillation signal of each layer of the transparent film layer to be measured into a frequency domain and amplitude spectrum with respect to time, and the frequency corresponding to the maximum amplitude is extracted for calculating parameters such as the sound velocity and Young's modulus of the film layer.

[0004] If the sample contains multiple transparent film layers, the measured signal within a single film layer will have a relatively low sampling frequency. The requirement of the Fourier transform for the sampling frequency causes the result of the Fourier transform at a relatively low sampling frequency to be distorted, ultimately affecting the calculation accuracy of parameters such as the sound velocity and Young's modulus of the film layer. Summary of the Invention

[0005] Embodiments of the present application provide a parameter measurement method and related devices for improving the calculation accuracy of parameters such as the sound velocity and Young's modulus of a transparent film layer.

[0006] A first aspect of an embodiment of the present application provides a parameter measurement method, including:

[0007] Obtaining a target measured signal of a target film layer in a sample, where the target measured signal is the signal returned by the target film layer when a measurement device measures the sample, and the sample includes multiple film layers;

[0008] Constructing a fitting function including multiple elementary functions, where the fitting function includes multiple unknown coefficients, the multiple elementary functions at least include trigonometric functions, the unknown coefficients include frequency coefficients of the trigonometric functions, and the fitting function is used to represent the change amount of the reflectivity of the target film layer when the measurement device measures the sample;

[0009] Fitting the fitting function and the target measured signal when the values of the multiple unknown coefficients are not all the same, and obtaining the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency;

[0010] Calculating the film layer parameters of the target film layer based on the target angular frequency.

[0011] In a specific implementation manner, when the target film layer is the i-th film layer from the sample substrate to the sample surface among the multiple film layers, the method further includes:

[0012] Determine the end time point of the measured signal of the (i - 1)-th film layer as the target start time point of the target measured signal;

[0013] Calculate the target end time point of the target measured signal according to the start time point of the target measured signal, the film thickness of the target film layer, and the reference sound velocity of the target film layer;

[0014] Obtain the signal measured by the measuring device between the target start time point and the target end time point as the target measured signal of the target film layer.

[0015] In a specific implementation manner, calculating the film layer parameters of the target film layer based on the target angular frequency includes:

[0016] Determine the quotient of the target angular frequency and twice the pi as the signal transmission frequency in the target film layer;

[0017] Calculate the film layer parameters of the target film layer based on the signal transmission frequency in the target film layer.

[0018] In a specific implementation manner, calculating the film layer parameters of the target film layer based on the signal transmission frequency in the target film layer includes:

[0019] Convert the periodic term of the sensitivity function of the target film layer into a trigonometric function, and obtain the angular frequency of the converted trigonometric function, where the sensitivity function is used to represent the response signal generated by the target film layer when stimulated by a signal;

[0020] Calculate the sound velocity of the target film layer based on the angular frequency of the converted trigonometric function and the signal transmission frequency.

[0021] In a specific implementation manner, the method further includes:

[0022] Construct a relationship between Young's modulus and sound velocity based on the calculation formula of Young's modulus and the calculation formula of sound velocity;

[0023] Calculate the Young's modulus of the target film layer based on the sound velocity of the target film layer and the relationship between Young's modulus and sound velocity.

[0024] In a specific implementation manner, when there are multiple target measured signals, and fitting the fitting function and the target measured signals in the case where the values of the multiple unknown coefficients are not completely the same, and obtaining the frequency coefficient of the trigonometric function with the highest corresponding fitting degree as the target angular frequency, includes:

[0025] When fitting the fitting function and each of the target measured signals under the condition that the values of the multiple unknown coefficients are not completely the same, when the fitting degree between the fitting function and each of the target measured signals is the highest, the frequency coefficient of the trigonometric function is used as the initial angular frequency;

[0026] The average value of the sum of each of the initial angular frequencies is determined as the target angular frequency.

[0027] In a specific implementation manner, the multiple elementary functions further include an exponential function and a polynomial function, and the fitting function is as follows:

[0028] f(t) = acos(bt + c) × e dt + gt 2 + ht + k

[0029] where f(t) is the change in reflectivity of the target film layer at time t, and a, b, c, d, g, h, and k are all unknown coefficients.

[0030] The second aspect of the embodiments of the present application provides a measuring device, including:

[0031] An acquisition unit, configured to acquire a target measured signal of a target film layer in a sample, where the target measured signal is a signal returned by the target film layer when the measuring device measures the sample, and the sample includes multiple film layers;

[0032] A construction unit, configured to construct a fitting function including multiple elementary functions, where the fitting function includes multiple unknown coefficients, the multiple elementary functions at least include trigonometric functions, the unknown coefficients include the frequency coefficients of the trigonometric functions, and the fitting function is used to represent the change in reflectivity of the target film layer of the sample measured by the measuring device;

[0033] A fitting unit, configured to fit the fitting function and the target measured signal under the condition that the values of the multiple unknown coefficients are not completely the same, and obtain the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency;

[0034] A calculation unit, configured to calculate the film layer parameters of the target film layer based on the target angular frequency.

[0035] In a specific implementation manner, the target film layer is the i-th film layer from the sample substrate to the sample surface among the multiple film layers, and the acquisition unit is further configured to determine the end time point of the measured signal of the (i - 1)-th film layer as the target start time point of the target measured signal;

[0036] The calculation unit is further configured to calculate a target end time point of the target measured signal according to a start time point of the target measured signal, a film thickness of the target film layer, and a reference sound velocity of the target film layer;

[0037] The acquisition unit is further configured to acquire a signal measured by the measuring device between the target start time point and the target end time point as the target measured signal of the target film layer.

[0038] In a specific implementation manner, the calculation unit is specifically configured to determine a signal transmission frequency in the target film layer by dividing the target angular frequency by twice the pi;

[0039] Calculate a film layer parameter of the target film layer based on the signal transmission frequency in the target film layer.

[0040] In a specific implementation manner, the calculation unit is specifically configured to convert a periodic term of a sensitivity function of the target film layer into a trigonometric function, and obtain an angular frequency of the converted trigonometric function, where the sensitivity function is used to represent a response signal generated by the target film layer when being stimulated by a signal;

[0041] Calculate a sound velocity of the target film layer based on the angular frequency of the converted trigonometric function and the signal transmission frequency.

[0042] In a specific implementation manner, the construction unit is further configured to construct a relationship between Young's modulus and sound velocity based on a calculation formula of Young's modulus and a calculation formula of sound velocity;

[0043] The calculation unit is further configured to calculate Young's modulus of the target film layer based on the sound velocity of the target film layer and the relationship between Young's modulus and sound velocity.

[0044] In a specific implementation manner, there are multiple target measured signals, and the fitting unit is specifically configured to fit the fitting function and each of the target measured signals when values of multiple unknown coefficients are not completely the same, and use a frequency coefficient of the trigonometric function as an initial angular frequency when a fitting degree between the fitting function and each of the target measured signals is the highest;

[0045] Determine an average value of a sum of each of the initial angular frequencies as the target angular frequency.

[0046] In a specific implementation manner, the multiple elementary functions further include an exponential function and a polynomial function, and the fitting function is as follows:

[0047] f(t) = acos(bt + c) × e dt + gt 2 + ht + k

[0048] Among them, f(t) is the change in reflectivity of the target film layer at time t, and a, b, c, d, g, h, and k are all unknown coefficients.

[0049] The third aspect of the embodiments of the present application provides a computer device, including:

[0050] A central processing unit, a memory, and an input / output interface;

[0051] The memory is a transient storage memory or a persistent storage memory;

[0052] The central processing unit is configured to communicate with the memory and execute the instruction operations in the memory to execute the method described in the first aspect.

[0053] The fourth aspect of the embodiments of the present application provides a computer program product containing instructions. When the computer program product runs on a computer, it causes the computer to execute the method described in the first aspect.

[0054] The fifth aspect of the embodiments of the present application provides a computer storage medium. Instructions are stored in the computer storage medium. When the instructions are executed on a computer, they cause the computer to execute the method described in the first aspect.

[0055] As can be seen from the above technical solutions, the embodiments of the present application have the following advantages: constructing a fitting function corresponding to the target measured signal of the target film layer, and determining the signal transmission frequency of the target film layer based on the trigonometric function terms in the fitted fitting function, and then calculating relevant film layer parameters based on the signal transmission frequency. By constructing a fitting function, the present application avoids Fourier transform and also avoids the result distortion of Fourier transform at low sampling frequencies, thereby ensuring the calculation accuracy of parameters such as film layer sound velocity and Young's modulus, which has practical significance for measuring uneven transparent film layers or photoacoustic signals with low signal-to-noise ratio. Description of the Drawings

[0056] Figure 1 It is a schematic diagram of a principle of photoacoustic measurement disclosed in an embodiment of the present application;

[0057] Figure 2 It is a schematic diagram of a process of a parameter measurement method disclosed in an embodiment of the present application;

[0058] Figure 3 It is an example diagram of a measured signal disclosed in an embodiment of the present application;

[0059] Figure 4 It is an example diagram of the fitting of a fitting function and a measured signal disclosed in an embodiment of the present application;

[0060] Figure 5A schematic structural diagram of the measuring device disclosed in the embodiments of the present application;

[0061] Figure 6 A schematic structural diagram of the computer device disclosed in the embodiments of the present application. Detailed implementation manners

[0062] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0063] The embodiments of the present application provide a parameter measurement method and related devices for improving the calculation accuracy of parameters such as the sound velocity and Young's modulus of a transparent film layer.

[0064] To better illustrate the parameter measurement method of the present application, please refer to Figure 1 , and the photoacoustic measurement principle will be explained below.

[0065] A beam of ultrashort pulsed laser (excitation light) is incident on the surface of the sample. A part of the light energy is absorbed to generate instantaneous thermal expansion, and then an ultrasonic pulse signal is excited. The generated ultrasonic pulse signal starts to transmit in the sample and is reflected and transmitted at the interfaces of different film layers in the sample. The reflected sound wave (i.e., the ultrasonic pulse signal) transmits back to the surface of the sample again. If the film layer on the surface of the sample is a transparent film layer, the optical characteristics of the film layer on the surface of the sample are constantly changing during the transmission process of the sound wave, forming a periodic change. Therefore, when the ultrasonic pulse signal transmits back to the surface of the sample and changes the reflectivity of the film layer on the surface of the sample, if a beam of probe light is incident on the point where the reflectivity changes for measurement, the reflected light intensity of the probe light will generate a periodic oscillation signal due to the change in reflectivity. According to the principle of Brillouin oscillation, the time required for the signal to pass through the target film layer can be obtained from the measurement of the above periodic change, and combined with the thickness of the target film layer, parameters such as the sound velocity and Young's modulus of the transparent film layer can be calculated.

[0066] Please continue to refer to Figure 2 , and the embodiments of the present application provide a parameter measurement method, including the following steps:

[0067] 201. Obtain the target measured signal of the target film layer in the sample. The target measured signal is the signal returned by the target film layer when the measuring device measures the sample, and the sample includes multiple film layers;

[0068] In the embodiments of the present application, by establishing a non-linear relationship between the sound velocity and the measured signal, the simulation signals at different sound velocities are fitted to obtain the sound velocity when the fitting effect between the above simulation signal and the measured signal is the best, and the Young's modulus is calculated based on this sound velocity.

[0069] For each film layer of the sample except the substrate, it is transparent or semi-transparent. Therefore, the measured signals of different film layers will return at different times. In order to accurately obtain the target measured signal of the target film layer in the sample, the present application needs to first determine the time period when the target measured signal of the target film layer returns, and then obtain all the signals in the corresponding time period as the target measured signal of the target film layer. In practical applications, the target measured signal of the target film layer can be obtained from the measured signal when calculating the film layer parameters, or can be pre-calculated and stored before calculating the film layer parameters, which is not specifically limited here.

[0070] 202. Construct a fitting function including a variety of elementary functions. The fitting function includes multiple unknown coefficients. The variety of elementary functions includes at least trigonometric functions. The unknown coefficients include the frequency coefficients of trigonometric functions. The fitting function is used to represent the change in reflectivity of the target film layer of the sample measured by the measuring device at different times.

[0071] By observing the measured signals of various transparent film layers, it can be found that the waveform of the measured signal is similar to the waveforms of sine-type functions and cosine-type functions. The physical meaning of the measured signal is the change in reflectivity of the film layer. Then the constructed fitting function is also used to simulate the change in reflectivity of the target film layer of the sample measured by the measuring device at different times, that is, to simulate the simulation signal corresponding to the measured signal.

[0072] Therefore, in order to avoid the step of performing Fourier transform, in the embodiments of the present application, by constructing a fitting function including trigonometric functions, the signal transmission frequency in the target film layer is obtained from the trigonometric function terms of the fitting function. Among them, in addition to trigonometric functions, the fitting function also includes other types of basic elementary functions, such as exponential functions, power functions, logarithmic functions, inverse trigonometric functions, constant functions, polynomial functions, cosine-type functions, and sine-type functions, etc. In addition, the coefficients of each elementary function in the fitting function are unknowns.

[0073] Actually, in order to maximize the fitting degree between the fitting function and the measured signal and obtain a more accurate angular frequency as much as possible, the coefficients in each function term can be made unknowns, and the value of each unknown can be obtained by fitting, specifically referring to the method of solving the frequency coefficients of trigonometric functions in the fitting function.

[0074] 203. Fit the fitting function and the target measured signal when the values of multiple unknown coefficients are not completely the same, and obtain the frequency coefficient of the trigonometric function with the highest corresponding fitting degree as the target angular frequency.

[0075] Fitting refers to determining the consistency between two curves. When the fitting function contains unknown coefficients, the fitting function is an uncertain curve. Therefore, the fitting in this step is to check the consistency between the fitting function and the target measured signal when the values of multiple unknown coefficients are not exactly the same. For example, if the unknown coefficients in the fitting function include a, b, c, and d, then there are countless combinations for making the values of multiple unknown coefficients not exactly the same. For example, in two value-taking cases, only one corresponding unknown coefficient is different among the four unknown coefficients {value-taking case 1: [1, 5, 4, 3], value-taking case 2: [1, 5, 2, 3]}, or all four unknown coefficients are different in two value-taking cases, which can be specifically configured as required. Through the optimization algorithm, the target value-taking case with the highest fitting degree can be solved, and the frequency coefficient of the trigonometric function in the target value-taking case is determined as the target angular frequency. Generally, the initial value [a0, b0, c0, d0] of the value-taking situation is input, and the unknown coefficients are iteratively fitted through the optimization algorithm. The evaluation of the fitting degree includes but is not limited to the sum of squared errors, the coefficient of determination, etc. The value-taking situation corresponding to the highest fitting degree is used as the output. The output is the target value-taking situation [a1, b1, c1, d1]. Among them, the evaluation of the fitting degree includes but is not limited to the sum of squared errors and the coefficient of determination, etc. The optimization algorithm includes but is not limited to the least squares method and the gradient descent method.

[0076] Since at least some of the coefficients of the function terms in the fitting function are unknowns, different expressions of the simulation signal at different sound speeds can be obtained by assigning different values to these unknown coefficients. Moreover, the embodiments of the present application have reasons to believe that when the fitting degree between the fitting function and the target measured signal of the target film layer is high enough, the fitting function is the expression of the target measured signal of the target film layer. Specifically, since the measured signal has periodicity, the angular frequency (i.e., the frequency coefficient) of the periodic term (i.e., the trigonometric function term) in the fitting function is the angular frequency corresponding to the measured signal.

[0077] Actually, if the measured signal is Figure 3 as shown, the fitting situation between the fitting function and the measured signal when the fitting degree is the highest can be referred to Figure 4 . Among them, the abscissa is time, the ordinate is the signal value, the curve with a higher value at 0 picoseconds is the fitting function, and the curve with a lower value at 0 picoseconds is the measured signal.

[0078] In some specific implementation manners, step 201 may obtain multiple target measured signals of the target film layer through a measuring device, and when obtaining the highest fitting degree between the fitting function and different measured signals, use the frequency coefficient of the trigonometric function in the fitting function as the initial angular frequency. Finally, use the average value of the sum of the initial angular frequencies as the target angular frequency. Compared with the method of calculating the target angular frequency by only using one target measured signal extracted from one measured signal, the embodiments of the present application measure multiple measured signals and calculate the target angular frequency based on the target measured signals corresponding to the target film layer obtained from different measured signals, fully considering the variability and distribution of the data, and being more capable of reflecting the true trend and law of the fitting function. Even if there are outliers or noises in the target measured signals, the method of fitting multiple target measured signals can also average these effects to a certain extent, so as to obtain a more reliable target angular frequency.

[0079] 204. Calculate the film layer parameters of the target film layer based on the target angular frequency.

[0080] After obtaining the target angular frequency of the target measured signal of the target film layer, all film layer parameters related to the angular frequency of the film layer can be calculated, such as the sound velocity and Young's modulus, etc. The specific calculation method depends on the film layer parameters to be calculated, and details can be seen in the related embodiments described later.

[0081] In the embodiments of the present application, a fitting function corresponding to the target measured signal of the target film layer is constructed, and based on the trigonometric function term in the fitted fitting function, the signal transmission frequency of the target film layer is determined, and then the related film layer parameters are calculated based on the signal transmission frequency. By constructing the fitting function in the present application, the Fourier transform is avoided, and the result distortion of the Fourier transform at a low sampling frequency is also avoided, thereby ensuring the calculation accuracy of parameters such as the sound velocity and Young's modulus of the film layer, and it can be applied to the measurement of inhomogeneous transparent film layers or photoacoustic signals with low signal-to-noise ratios.

[0082] In some specific implementation manners, when the target film layer is the i-th film layer from the sample substrate to the sample surface among the multiple film layers, the target measured signal of the target film layer can be specifically determined through the following steps: determine the end time point of the measured signal of the (i - 1)-th film layer as the target start time point of the target measured signal; calculate the target end time point of the target measured signal according to the start time point of the target measured signal, the film thickness of the target film layer, and the reference sound velocity of the target film layer; obtain the signal measured by the measuring device from the target start time point to the target end time point as the target measured signal of the target film layer.

[0083] Take Figure 1 as an example. Assume that there are n transparent thin films from the substrate to the surface of the sample to be measured. Then the measured signal corresponding to the i-th transparent thin film should be at the time of ts i after the measuring device emits the probing light until tei between moments. Wherein, ts i is the starting time point of the measured signal of the i-th layer of transparent film, and te i is the ending time point of the measured signal of the i-th layer. The 0 moment is the starting time point of the signal of the n-th layer of transparent film detected. Therefore, there is:

[0084]

[0085] ts i+1 = te i (i = 1, 2,..., n - 1)

[0086] Wherein, T i represents the film thickness of the i-th film layer, that is, the film thickness of the i-th film layer, and V i represents the reference sound velocity of the i-th film layer. It can be understood that the sound velocity of the film layer determines the transmission speed in the signal film layer. Therefore, in order to roughly determine the starting time point and the ending time point of the target measured signal to obtain the target measured signal of the target film layer, the time period where the measured signal is located can be calculated through the reference sound velocity of the target film layer. It should be noted that the reference sound velocity is measured using a specified liquid or solid material under specific temperature and pressure according to the standard test method. However, the actual use environment of the thin film is different from the standard test environment, and the actual sound velocity will also be different. Therefore, the reference sound velocity of the film layer cannot accurately reflect the actual sound velocity of the film layer.

[0087] Please continue to refer to Figure 3 , Figure 3 which is the measured signal obtained by the measuring device. The sample corresponding to this measured signal is a SiO2(1900nm) film with Cr as the substrate. According to the above time point calculation formula, Figure 3 in [10, 200] ps in

[0088] is the signal during the process of the sound wave propagating from the interface between SiO2 and Cr to the film surface, and [200, 400] ps is the signal during the process of the sound wave reflecting back from the sample surface to the above interface. The signal oscillation frequencies in the first two ranges are all reflections of the sound velocity of SiO2. In fact, the signal within [10, 200] ps can be taken as the measured signal of the SiO2 film for fitting.

[0089]

[0090] where δR(t) is the change in reflectivity of the film layer at time t, f(z) is the sensitivity function, and η(z,t) is the strain of the film layer with thickness z at time t. Among them, the sensitivity function of the thin film (also known as the response function or transfer function) refers to the response signal or output signal generated by the thin film when stimulated by an external signal or an input signal. This function describes how the thin film converts the input signal into an output signal and reflects the physical and chemical properties of the thin film and its interaction with the external environment.

[0091] Therefore, for the light wave (i.e., the probing light) vertically incident on the target film layer, the periodic term of the sensitivity function in the aforementioned formula (1) can be written as This trigonometric function form, where n is the refractive index of the target film layer, V represents the (actual) sound velocity of the target film layer, λ is the wavelength of the probing light, and ω is the target angular frequency. Therefore, the relationship between the signal frequency in the change in reflectivity δR(t) and the sound velocity can be deduced as

[0092]

[0093] According to the above analysis, when the wavelength of the probing light and the refractive index of the target film layer are known, only the frequency of the measured signal needs to be obtained to calculate the sound velocity V. At the same time, as previously recorded, when the fitting degree between the fitting function and the target measured signal of the target film layer is high enough, the fitting function is the expression of the target measured signal of the target film layer, that is, it can be considered that the angular frequency (i.e., the frequency coefficient) of the periodic term (i.e., the trigonometric function term) in the fitting function is the angular frequency of the measured signal.

[0094] In practical applications, the periodic term of the sensitivity function can be directly converted into the trigonometric function form, and the value of the angular frequency after the periodic term is converted into the trigonometric function is the target angular frequency ω. In this way, the sound velocity of the target film layer can be solved. If the periodic term of the sensitivity function can be written as This trigonometric function form, then the sound velocity V of the target film layer can be calculated through In this embodiment, the angular frequency after the periodic term of the sensitivity function is converted into the trigonometric function is

[0095] Alternatively, based on the conversion formula between angular frequency and frequency (2πν = ω), first obtain the (signal) transmission rate of the signal in the target film layer, and then solve the sound velocity of the target film layer through the relationship between the signal transmission rate and the angular frequency after the periodic term of the sensitivity function is converted into the trigonometric function. If the periodic term of the sensitivity function can be written as This trigonometric function form, then the sound velocity V of the target film layer can be calculated through In this embodiment, the angular frequency after the periodic term of the sensitivity function is converted into the trigonometric function is

[0096]

[0097] Furthermore, after obtaining the sound velocity of the target film layer, based on the relational expression between Young's modulus and sound velocity it can be known that the Young's modulus E of the target film layer can be calculated through the Poisson's ratio μ of the target film layer, the density ρ of the target film layer, and the sound velocity V of the target film layer.

[0098] Based on the foregoing embodiments, in some specific implementation manners, the fitting function including trigonometric functions, exponential functions, and polynomial functions may be f(t) = acos(bt + c) × e dt + gt 2 + ht + k, where f(t) is the change amount of the reflectivity of the target film layer at time t, and a, b, c, d, g, h, and k are all position coefficients. It should be noted that the fitting function provided in the embodiments of the present application is only for illustration, and the unknown coefficients (a, b, c, d, g, h, and k) that may be included in the fitting function are not specific limitations on the trigonometric functions, exponential functions, and polynomial functions in the embodiments of the present application.

[0099] Please refer to Figure 5 , an embodiment of the present application provides a measuring device, including:

[0100] An acquisition unit 501, configured to acquire a target measured signal of a target film layer in a sample when the measuring device measures the sample, where the sample includes multiple film layers;

[0101] A construction unit 502, configured to construct a fitting function including multiple elementary functions, the fitting function includes multiple unknown coefficients, the multiple elementary functions at least include trigonometric functions, and the frequency coefficient of the trigonometric function is an unknown coefficient, and the fitting function is used to represent the change amount of the reflectivity of the target film layer at different times when the measuring device measures the sample;

[0102] A fitting unit 503, configured to fit the fitting function and the target measured signal when the values of the multiple unknown coefficients are different, and obtain the frequency coefficient of the trigonometric function with the highest corresponding fitting degree as the target angular frequency;

[0103] A calculation unit 504, configured to calculate the film layer parameters of the target film layer based on the target angular frequency.

[0104] In a specific implementation manner, the target film layer is the i-th film layer from the sample substrate to the sample surface among the multiple film layers. The acquisition unit 501 is specifically configured to determine the end time point of the measured signal of the (i - 1)-th film layer as the target start time point of the target measured signal;

[0105] Calculate the target end time point of the target measured signal according to the start time point of the target measured signal, the film thickness of the target film layer, and the reference sound velocity of the target film layer;

[0106] Obtain the signal measured by the measuring device from the target start time point to the target end time point as the target measured signal of the target film layer.

[0107] In a specific implementation manner, the calculation unit 504 is specifically configured to determine the quotient of the target angular frequency and twice the pi as the signal transmission frequency in the target film layer;

[0108] Calculate the film layer parameters of the target film layer based on the signal transmission frequency in the target film layer.

[0109] In a specific implementation manner, the calculation unit 504 is specifically configured to convert the periodic term of the sensitivity function of the target film layer into a trigonometric function and obtain the angular frequency of the converted trigonometric function;

[0110] Calculate the sound velocity of the target film layer based on the angular frequency of the converted trigonometric function and the signal transmission frequency.

[0111] In a specific implementation manner, the method further includes:

[0112] The construction unit 502 is further configured to construct a relationship between the Young's modulus and the sound velocity based on the calculation formula of the Young's modulus and the calculation formula of the sound velocity;

[0113] The calculation unit 504 is further configured to calculate the Young's modulus of the target film layer based on the sound velocity of the target film layer and the relationship between the Young's modulus and the sound velocity.

[0114] In a specific implementation manner, there are multiple target measured signals. The fitting unit 503 is specifically configured to use different values as the coefficients in various elementary functions. When the fitting degree between the fitting function and each target measured signal is the highest, the frequency coefficient of the trigonometric function is used as the initial angular frequency;

[0115] Determine the average value of each initial angular frequency as the target angular frequency.

[0116] In a specific implementation manner, the various elementary functions further include an exponential function and a polynomial function. The fitting function is as follows:

[0117] f(t) = acos(bt + c) × e dt + gt 2 + ht + k

[0118] where f(t) is the change in reflectivity of the target film layer at time t, and a, b, c, d, g, h, and k are all unknown coefficients.

[0119] Figure 66 is a schematic diagram of a computer device structure provided in an embodiment of the present application. The computer device 600 may include one or more central processing units (CPU) 601 and a memory 605. The memory 605 stores one or more application programs or data.

[0120] The memory 605 may be a volatile storage or a persistent storage. The program stored in the memory 605 may include one or more modules, each of which may include a series of instruction operations in the computer device. Furthermore, the central processing unit 601 may be configured to communicate with the memory 605 and execute a series of instruction operations in the memory 605 on the computer device 600.

[0121] The computer device 600 may also include one or more power supplies 602, one or more wired or wireless network interfaces 603, one or more input and output interfaces 604, and / or one or more operating systems, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.

[0122] The CPU 601 can execute the aforementioned Figures 1 to 5 The operations performed by the measuring device in the illustrated embodiment will not be described in detail herein.

[0123] It should be noted that, although the steps in the flowcharts involved in the embodiments are drawn in sequence according to the indications of the arrows, unless otherwise clearly stated in this document, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0124] Those skilled in the art can 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.

[0125] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods 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 may 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, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0126] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they may be located in one place, or they may 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.

[0127] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0128] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing 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 methods described in each embodiment of the present application. And the aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, read-only memory), random access memories (RAM, random access memory), magnetic disks, or optical discs, etc., which can store program codes.

[0129] The embodiments of the present application also provide a computer program product containing instructions. When the computer program product runs on a computer, it causes the computer to execute the parameter measurement method as described above.

Claims

1. A parameter measurement method, characterized in that, Including: Obtaining a target measured signal of a target film layer in a sample, where the target measured signal is a signal returned by the target film layer when a measuring device measures the sample, and the sample includes multiple film layers; Constructing a fitting function including multiple elementary functions, the fitting function including multiple unknown coefficients, the multiple elementary functions at least including trigonometric functions, the unknown coefficients including frequency coefficients of the trigonometric functions, and the fitting function being used to represent the change in reflectivity of the target film layer of the sample measured by the measuring device; Fitting the fitting function and the target measured signal when the values of the multiple unknown coefficients are not all the same, and obtaining the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency; Calculating a film layer parameter of the target film layer based on the target angular frequency.

2. The method according to claim 1, wherein The target film layer is the i-th film layer from the sample substrate to the sample surface among the multiple film layers, and the method further includes: Determining the end time point of the measured signal of the (i - 1)-th film layer as the target start time point of the target measured signal; Calculating the target end time point of the target measured signal according to the start time point of the target measured signal, the film thickness of the target film layer, and the reference sound speed of the target film layer; Obtaining the signal measured by the measuring device between the target start time point and the target end time point as the target measured signal of the target film layer.

3. The method according to claim 1, wherein The calculating the film layer parameter of the target film layer based on the target angular frequency includes: Determining the quotient of the target angular frequency and twice the pi as the signal transmission frequency in the target film layer; Calculating the film layer parameter of the target film layer based on the signal transmission frequency in the target film layer.

4. The method according to claim 3, wherein The calculating the film layer parameter of the target film layer based on the signal transmission frequency in the target film layer includes: Converting the periodic term of the sensitivity function of the target film layer into a trigonometric function, and obtaining the angular frequency of the converted trigonometric function, where the sensitivity function is used to represent the response signal generated when the target film layer is stimulated by a signal; Calculating the sound speed of the target film layer based on the angular frequency of the converted trigonometric function and the signal transmission frequency.

5. The method according to claim 4, wherein The method further includes: Constructing a relationship between Young's modulus and sound speed based on the calculation formula of Young's modulus and the calculation formula of sound speed; Calculating the Young's modulus of the target film layer based on the sound speed of the target film layer and the relationship between Young's modulus and sound speed.

6. The method according to claim 1, wherein There are multiple target measured signals, and the fitting the fitting function and the target measured signals when the values of the multiple unknown coefficients are not all the same, and obtaining the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency includes: Fitting the fitting function and each of the target measured signals when the values of the multiple unknown coefficients are not all the same, and taking the frequency coefficient of the trigonometric function when the fitting degree between the fitting function and each of the target measured signals is the highest as the initial angular frequency; Determining the average value of the sum of each of the initial angular frequencies as the target angular frequency.

7. The method according to claim 1, characterized in that, The multiple elementary functions further include exponential functions and polynomial functions, and the fitting function is as follows: f(t) = a cos(bt + c) × e dt + gt 2 + ht + k where f(t) is the change in reflectivity of the target film layer at time t, and a, b, c, d, g, h, and k are all unknown coefficients.

8. A measuring device, characterized in that, It includes: An acquisition unit configured to acquire a target measured signal of a target film layer in a sample, where the target measured signal is a signal returned by a measurement device measuring the target film layer of the sample, and the sample includes multiple film layers; A construction unit configured to construct a fitting function including multiple elementary functions, the fitting function including multiple unknown coefficients, the multiple elementary functions at least including trigonometric functions, the unknown coefficients including frequency coefficients of the trigonometric functions, and the fitting function being used to represent the change in reflectivity of the target film layer of the sample measured by the measurement device; A fitting unit configured to fit the fitting function and the target measured signal when the values of the multiple unknown coefficients are not all the same, and acquire the frequency coefficient of the trigonometric function when the corresponding fitting degree is the highest as the target angular frequency; A calculation unit configured to calculate the film layer parameters of the target film layer based on the target angular frequency.

9. A computer device, characterized in that, It includes: A central processing unit, a memory, and an input / output interface; The memory is a transient storage memory or a persistent storage memory; The central processing unit is configured to communicate with the memory and execute the instruction operations in the memory to execute the method according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that, Instructions are stored in the computer storage medium, and when the instructions are executed on a computer, the computer is caused to execute the method according to any one of claims 1 to 7.

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