Semiconductor thin film uniformity nondestructive testing method and system

Abstract

The present invention provides a method and system for nondestructive testing of uniformity of semiconductor thin films. The sample to be tested includes a substrate and a semiconductor thin film arranged on the surface of the substrate. The method includes: incident light is incident on a measuring point on the surface of the sample to be tested at a set incident angle, and optical parameters of the measuring point are obtained at a set wavelength or a set wavelength range, and the optical parameters include the refractive index and extinction coefficient of the semiconductor thin film and / or the curvature radius of the sample to be tested; the optical parameters of the sample to be tested are used as known parameters, and a physical model is applied to obtain the measurement parameters of the semiconductor thin film, and the measurement parameters include the relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor thin film; the above steps are repeated to obtain the measurement parameters of multiple measurement points; and the uniformity of the same measurement parameters of multiple measurement points is evaluated. The method of the present invention can realize nondestructive measurement, and the measurement parameters obtained are not single, which meets diversified needs.

Description

Technical Field

[0001] The present disclosure relates to the field of integrated circuits, and in particular to a method and system for non-destructive uniformity detection of semiconductor thin films. Background Art

[0002] Semiconductor films are widely used in micro-electromechanical systems (MEMS). Semiconductor films can include piezoelectric films, ferroelectric films, dielectric films and other films related to semiconductor materials. The uniformity of their physical properties is an important indicator for measuring product quality and is also one of the main performance indicators affecting the performance of back-end MEMS devices. Therefore, semiconductor film uniformity detection technology is an indispensable detection technology in the industrialization of semiconductor films.

[0003] The detection of semiconductor film uniformity includes the detection of relative dielectric constant, piezoelectric coefficient, stress, and thickness uniformity. However, the existing detection methods cannot meet the needs. For example, one method of detecting the relative dielectric constant is to use optical means to measure the relative dielectric constant of the film in the terahertz frequency band, but it cannot feedback the relative dielectric constant at low frequency, and cannot correctly predict the performance of the back-end device; another method of detecting the relative dielectric constant is the probe method, which requires the conductive electrode to be plated on the surface of the semiconductor film before measurement. The semiconductor film will inevitably be damaged during the measurement process, which seriously affects the subsequent device application; the method of detecting stress requires multiple measurements of the multi-layer film layer by layer, which is inefficient; the method of measuring thickness is mainly optical interference, but this method cannot feedback the uniformity of the electrical properties of the semiconductor film.

[0004] Therefore, there is an urgent need to provide a new type of non-destructive detection method and detection system for semiconductor thin film uniformity to solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present disclosure is to provide a method and system for detecting uniformity of a semiconductor thin film, which can non-destructively detect the uniformity of a semiconductor thin film and expand the application of semiconductor thin films in devices.

[0006] In order to solve the above problems, the present disclosure provides a method for detecting uniformity of a semiconductor thin film, wherein a sample to be tested includes a substrate and a semiconductor thin film disposed on the surface of the substrate, and the method includes:

[0007] The incident light is incident on the measuring point on the surface of the sample to be measured at a set incident angle, and the optical parameters of the measuring point at a set wavelength or a set wavelength range are obtained, wherein the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be measured;

[0008] Taking the optical parameters of the sample to be measured as known parameters, applying the physical model to obtain the measurement parameters of the semiconductor film, wherein the measurement parameters include the relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film;

[0009] Repeat the above steps to obtain the measurement parameters of multiple measurement points;

[0010] The uniformity of the same measurement parameter at multiple measurement points is evaluated.

[0011] The present invention also provides a system for realizing the above-mentioned semiconductor thin film uniformity detection, which comprises:

[0012] A sample stage, used for placing a sample to be tested, wherein the sample to be tested includes a substrate and a semiconductor film arranged on the substrate, and the sample stage can rotate and move along a set direction;

[0013] An optical detection unit, used for providing incident light and obtaining ellipsometric parameters of reflected light at a measuring point of the sample to be measured, and / or forming a reflected light array and receiving information of the reflected light array;

[0014] An analysis unit, used for obtaining optical parameters of the measuring point of the sample to be measured at a set wavelength or a set wavelength range according to the ellipsometric parameters and / or the reflected light array information, wherein the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be measured;

[0015] A physical model unit, used for obtaining measurement parameters of the semiconductor film by applying a physical model, wherein the measurement parameters include relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film;

[0016] An evaluation unit is used to evaluate the uniformity of the same measurement parameter at multiple measurement points.

[0017] The semiconductor thin film uniformity detection method provided by the present invention can measure optical parameters using optical methods, and then use the optical parameters as known quantities to obtain the measurement parameters of the semiconductor thin film according to the physical model, thereby realizing the evaluation of the uniformity of the measurement parameters. The detection method of the present invention can realize non-destructive measurement of semiconductor thin films, and the obtained measurement parameters are not single, which meets diversified needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the steps of the semiconductor thin film uniformity detection method of the present invention;

[0019] Figure 2 This is the thickness distribution of the lead zirconate titanate film on the surface of a 3-inch wafer;

[0020] Figure 3This is the relative dielectric constant distribution diagram of lead zirconate titanate film on the surface of a 3-inch wafer;

[0021] Figure 4 This is the piezoelectric coefficient distribution diagram of lead zirconate titanate film on the surface of a 3-inch wafer;

[0022] Figure 5 This is the stress distribution diagram of lead zirconate titanate film on the surface of a 3-inch wafer;

[0023] Figure 6 It is a schematic diagram of the structure of the system of the present invention. DETAILED DESCRIPTION

[0024] The specific implementation of the semiconductor thin film uniformity detection method and system provided by the present disclosure is described in detail below with reference to the accompanying drawings.

[0025] Existing semiconductor thin film uniformity detection methods cannot achieve non-destructive detection. In view of this, an embodiment of the present invention provides a semiconductor thin film uniformity detection method, which can achieve non-destructive detection of semiconductor thin film uniformity, avoid damage to the semiconductor film, and expand the application scope of the semiconductor film.

[0026] In an embodiment of the present invention, the sample to be tested includes a substrate and a semiconductor film disposed on the surface of the substrate, the surface of the semiconductor film serves as the surface of the sample to be tested, and the bottom surface of the substrate serves as the bottom surface of the sample to be tested. The semiconductor film uniformity detection includes the detection of relative dielectric constant uniformity, piezoelectric coefficient uniformity, stress uniformity and thickness uniformity.

[0027] See also Figure 1 , which is a schematic diagram of the steps of the semiconductor thin film uniformity detection method of the present invention, the semiconductor thin film uniformity detection method of the present invention comprises the following steps:

[0028] Step S10, incident light is incident on a measuring point on the surface of the sample to be measured at a set incident angle to obtain optical parameters of the measuring point at a set wavelength or a set wavelength range, wherein the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be measured.

[0029] The wavelength range of the incident light is 200nm-3000nm, and the incident angle is 0-90 degrees. In this embodiment, the incident angle is determined first, and the subsequent light sources are incident at the set incident angle to avoid the test results being affected by different incident angles.

[0030] The measuring point is a point on the surface of the semiconductor film, and its position can be set according to actual needs. For example, in some embodiments, the sample to be measured is a wafer, and the center of the wafer can be set as the first measuring point. When repeated measurements are made, other measuring points can be selected gradually from the center of the wafer to the edge of the wafer.

[0031] The optical parameters are different according to the different measurement parameters of the semiconductor film to be obtained. For example, in this embodiment, the thickness, relative dielectric constant, piezoelectric coefficient and stress of the semiconductor film need to be obtained later, and the optical parameters include the refractive index, extinction coefficient and curvature radius of the sample to be measured of the semiconductor film, while in other embodiments, the thickness, relative dielectric constant and piezoelectric coefficient of the semiconductor film need to be obtained later, and the optical parameters include the refractive index and extinction coefficient of the semiconductor film.

[0032] As an example, the present invention provides a method for obtaining the optical parameters of the measurement point at a set wavelength or a set wavelength range. The method comprises the following steps:

[0033] Obtain the ellipsometric parameters of the incident light at the measuring point. In some embodiments, the ellipsometric parameters of the incident light at a certain set wavelength are obtained at the measuring point. In other embodiments, the variation of the ellipsometric parameters of the incident light at the measuring point with the wavelength within the set wavelength range is obtained, that is, within the set wavelength range, multiple wavelengths and the ellipsometric parameters corresponding to each wavelength are obtained. The ellipsometric parameters include an amplitude ratio ψ and a phase difference Δ. Further, in some embodiments, after obtaining the ellipsometric parameters corresponding to multiple wavelengths and each wavelength, a spectrum can be drawn with the wavelength as the horizontal coordinate and the amplitude ratio or phase difference as the vertical coordinate.

[0034] Taking the ellipsometric parameters as known parameters, multiple dispersion models are applied to respectively fit and obtain initial values ​​of multiple refractive indices and extinction coefficients.

[0035] Different types of materials and different thin film structures are suitable for different dispersion models. In this embodiment, a suitable dispersion model can be selected according to the material type and semiconductor film structure of the substrate and semiconductor film of the sample to be tested. There may be multiple dispersion models suitable for the sample to be tested, and multiple suitable dispersion models can be selected to fit and obtain initial values ​​of multiple refractive indices and extinction coefficients.

[0036] In some embodiments, the dispersion model includes the NK model (commonly used for metal substrates, silicon substrates, etc.), the Cauchy model (commonly used for transparent materials), the Cauchy index model (commonly used for oxides and semiconductor materials), the Forouhi-Bloomer model (applicable to semiconductor dielectric materials), the Lorentz model (commonly used for semiconductor materials, insulators and crystalline materials or materials with unknown characteristics), the Sellmeier model (commonly used for transparent materials or materials that are transparent in a certain band), the effective medium approximation model (commonly used for mixed medium systems composed of different components), and the Tauc-Lorentz model (widely used in amorphous, polycrystalline or amorphous / crystalline mixed materials).

[0037] As described above, there may be multiple dispersion models suitable for the sample to be tested. Therefore, it is necessary to evaluate the fitting results of the selected dispersion model to obtain accurate refractive index and extinction coefficient.

[0038] In this embodiment, the first evaluation function is used to evaluate the dispersion model fitting result, and the initial values ​​of the refractive index and the extinction coefficient obtained by the dispersion model fitting that meet the preset standard are selected as the optical parameters. For example, in this embodiment, the first evaluation function includes a root mean square error evaluation function (MSE), and the root mean square error is obtained by using the root mean square error evaluation function for the dispersion model fitting result; the initial values ​​of the refractive index and the extinction coefficient obtained by the dispersion model fitting corresponding to the minimum root mean square error are used as the optical parameters.

[0039] The root mean square error evaluation function (MSE) is as follows:

[0040]

[0041] Where ψ is the amplitude ratio, Δ is the phase difference, N is the number of amplitude ratios or phase differences, M is the number of parameters obtained by the fitting model, mod is the calculated value obtained according to the fitting model, exp is the measured value of the device itself, and ε is the measurement error of the amplitude ratio or phase difference.

[0042] In some embodiments, for the case where there are multiple wavelengths and their corresponding ellipsometric parameters, each dispersion model is fitted to obtain the initial values ​​of the refractive index and extinction coefficient corresponding to each wavelength, that is, the same dispersion model can obtain multiple fitting results. Then, when the first evaluation function is used to evaluate the dispersion model fitting results, the dispersion model can be more fully evaluated, thereby improving the accuracy of the evaluation.

[0043] Further, in some embodiments, when multiple fitting results can be obtained from the same dispersion model, multiple spectra can be formed with the wavelength as the horizontal coordinate and the refractive index or extinction coefficient as the vertical coordinate.

[0044] In some embodiments, for a known semiconductor thin film material and its corresponding dispersion model, the corresponding dispersion model may be directly used for fitting, and the fitting result may be evaluated using a first evaluation function to detect its fitting accuracy.

[0045] Please continue reading Figure 1 In step S11, the optical parameters of the sample to be tested are used as known parameters, and the physical model is applied to obtain the measurement parameters of the semiconductor film, wherein the measurement parameters include the relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film.

[0046] In this step, according to the difference of the measurement parameters, the corresponding physical model is selected to obtain the measurement parameters.

[0047] As an example, the present invention provides a method for obtaining the thickness of the semiconductor film by applying a physical model. When the light source wavelength, the incident angle of light, the substrate and other parameters are constant, the ellipsometric parameters (including the amplitude ratio and the phase difference) are functions of the thickness and the refractive index of the semiconductor film. Theoretically, the thickness and the refractive index of the film can be obtained by the amplitude ratio and the phase difference, but the specific form of the thickness d = (ψ, Δ) and the refractive index n = (ψ, Δ) cannot be analyzed at present. Therefore, the method of the present invention for obtaining the thickness of the semiconductor film by applying a physical model includes:

[0048] The wavelength of the incident light, the incident angle and the refractive index of the semiconductor film (obtained in step S10) are used as known parameters of the physical model to obtain a comparison table of ellipsometric parameters, thickness and refractive index. The comparison table is known data, which is a table of correspondence between ellipsometric parameters and thickness under a set range of incident light wavelength, range of incident angle and range of refractive index of the semiconductor film. The physical model includes a database consisting of a plurality of comparison tables. In this step, a corresponding comparison table can be obtained in the database according to the wavelength of the incident light, the incident angle and the refractive index of the semiconductor film. The comparison table may include a spectrum with wavelength as the horizontal coordinate and amplitude ratio as the vertical coordinate, or a spectrum with wavelength as the horizontal coordinate and phase difference as the vertical coordinate and the thickness corresponding to these spectra.

[0049] The ellipsometric parameters of the incident light at the measuring point are used as the query parameters of the physical model, and the thickness of the semiconductor film is obtained in the comparison table. In this step, the amplitude ratio and phase difference of the incident light at the measuring point are used as the query parameters, and the thickness of the semiconductor film corresponding to the amplitude ratio and phase difference of the incident light at the measuring point is obtained in the comparison table obtained in the previous step.

[0050] Furthermore, in some embodiments, a spectrum of the amplitude ratio or phase difference of the incident light at the measuring point (a spectrum consisting of the wavelength as the horizontal coordinate and the amplitude ratio as the vertical coordinate, or a spectrum consisting of the wavelength as the horizontal coordinate and the phase difference as the vertical coordinate) is used as a measurement spectrum (i.e., the query parameter) and compared with a standard spectrum in a comparison table, and the thickness corresponding to the standard spectrum in the comparison table with the highest similarity to the measurement spectrum is used as the thickness of the semiconductor film.

[0051] The semiconductor film thickness measurement method provided by the present invention utilizes known parameters through an existing database, including the wavelength of the incident light, the incident angle, the refractive index of the semiconductor film, the amplitude ratio and the phase difference of the incident light at the measurement point, so as to obtain the thickness of the semiconductor film without measuring the multi-layer film layer by layer, thereby greatly improving the detection efficiency.

[0052] As an example, the present invention provides a method for obtaining the relative dielectric constant of the semiconductor film by applying a physical model.

[0053] There are four main contribution mechanisms to the relative dielectric constant of dielectric materials, namely space charge polarization, double ion polarization, ion polarization and electronic polarization. Among them, ion polarization and double ion polarization are the main contribution mechanisms to the relative dielectric constant in dielectric materials. 5 Hz, the relative dielectric constant has the above four relative dielectric constant contribution mechanisms; when the frequency is higher than 10 5 Hz, the space charge polarization contribution mechanism gradually fails, and the relative dielectric constant drops sharply at this frequency; when the frequency is higher than 10 9 Hz, the contribution mechanism of the even ion polarization gradually fails, and the relative dielectric constant drops sharply near this frequency; when the frequency is higher than 10 12 Hz, the ion polarization contribution mechanism gradually fails, and the relative dielectric constant drops sharply in this frequency range; when the frequency range reaches 10 14 -10 15 When the frequency is near Hz, the relative dielectric constant is very small and is only contributed by electron polarization.

[0054] In this embodiment, the wavelength range of the incident light is 200nm-3000nm, and the corresponding frequency is 10 14 Hz~1.5×10 15 Hz. The frequency range of the incident light is defined as the first frequency, that is, the first frequency is 10 14 Hz~1.5×10 15Hz. Since the back-end devices will not work at such a high frequency in actual use, the electrical performance parameters such as the relative dielectric constant obtained in the above frequency range are worthless, so it is necessary to obtain the electrical performance parameters such as the relative dielectric constant in the low frequency band. As analyzed above, the relative dielectric constant of the semiconductor film at the first frequency depends on the electron polarization, which can be calculated by 10 14 ~10 15 The relative dielectric constant in the Hz frequency band, that is, the relative dielectric constant contributed by electron polarization, is gradually calculated to obtain the relative dielectric constant of the semiconductor film at low frequency.

[0055] In this embodiment, the physical model includes a first relative dielectric constant model and a second relative dielectric constant model, and the method for obtaining the relative dielectric constant of the semiconductor film by applying the physical model includes the following steps:

[0056] The relative dielectric constant ε1 of the semiconductor film at the first frequency is obtained according to the first relative dielectric constant model. At the first frequency, the first relative dielectric constant model includes the following formula:

[0057] ε1=n 2 -k 2

[0058] Wherein, n is the refractive index of the semiconductor film, and k is the extinction coefficient of the semiconductor film. The refractive index of the semiconductor film and the extinction coefficient of the semiconductor film have been obtained in step S10. In the case where multiple wavelengths and their corresponding refractive indices and extinction coefficients of the semiconductor film are obtained within a set wavelength range in step S10, in this step, the refractive index of the semiconductor film and the extinction coefficient of the semiconductor film at a certain set wavelength are selected as parameters of the first relative dielectric constant model.

[0059] Further, in this step, the dielectric loss of the semiconductor film can be obtained by using the optical parameters of the sample to be tested as known parameters and applying the physical model, including: applying the following formula to obtain the dielectric loss ε2 of the semiconductor film:

[0060] ε2=2nk

[0061] Wherein, n is the refractive index of the semiconductor film, and k is the extinction coefficient of the semiconductor film. In the case where multiple wavelengths and their corresponding refractive indices and extinction coefficients of the semiconductor film are obtained within the set wavelength range in step S10, in this step, the refractive index of the semiconductor film and the extinction coefficient of the semiconductor film at a certain set wavelength are selected as parameters for calculating the dielectric loss of the semiconductor film.

[0062] After obtaining the relative dielectric constant corresponding to the first frequency, using the relative dielectric constant corresponding to the first frequency as a known parameter, multiple second relative dielectric constant models are applied to respectively fit and obtain multiple relative dielectric constants of the semiconductor film at a second frequency, wherein the second frequency is less than the first frequency. For example, in this embodiment, the second frequency is 10 12 Hz, this method can be used to obtain 10 12 Relative dielectric constant corresponding to Hz.

[0063] Different materials of the samples to be tested have different relative dielectric constant models, so the samples to be tested in the present invention may correspond to multiple second relative dielectric constant models. The second relative dielectric constant model includes at least two of a half-quantum model, a relaxation oscillation model, a Debye relaxation model, a damped resonator model, and a pseudoharmonic model.

[0064] The specific expression of the semi-quantum model is:

[0065]

[0066]

[0067] In the formula, ε ∞1 is the relative dielectric constant contributed by ionic polarization, ε ∞ is the relative dielectric constant contributed by the electronic polarization (i.e., the relative dielectric constant corresponding to the first frequency), n is the number of phonon models, γ is the damping factor, TO and LO are the transverse and longitudinal optical models, ω is the angular frequency, ε0 ​​is the relative dielectric constant at low frequency, g i is the relaxation time distribution, τ i is the relaxation time.

[0068] The relaxation oscillation model is based on the ferroelectric soft mode theory and dielectric relaxation theory, and couples a relaxation oscillation model. Its specific expression is:

[0069]

[0070] In the formula, ε ∞ is the relative dielectric constant contributed by the electronic polarization (i.e., the relative dielectric constant corresponding to the first frequency), Γ, f, ω s are the damping coefficient, oscillator strength and characteristic frequency in the soft mode, γ c and g are the frequency and strength in the Debye relaxation model, respectively, δ is the coupling coefficient, and ω is the angular frequency.

[0071] The specific expression of the Debye relaxation model is:

[0072]

[0073] Among them, ε ∞ is the relative dielectric constant contributed by electronic polarization (i.e., the relative dielectric constant corresponding to the first frequency), ε S is the relative dielectric constant at low frequency, ω is the angular frequency, and τ is the relaxation time.

[0074] A second evaluation function is used to evaluate the accuracy of the second relative dielectric constant model, and a relative dielectric constant obtained by fitting the second relative dielectric constant model that meets a preset standard is selected as the relative dielectric constant of the semiconductor film at the second frequency.

[0075] The specific expression of the damped resonator model is:

[0076]

[0077] Among them, ε ∞ is the relative dielectric constant contributed by electronic polarization (i.e., the relative dielectric constant corresponding to the first frequency), ω j and γ j are the resonant frequency and damping factor of the jth phonon model, and ω is the angular frequency.

[0078] The specific expression of the pseudoharmonic model is:

[0079]

[0080] Among them, ε ∞ is the relative dielectric constant contributed by electronic polarization (i.e., the relative dielectric constant corresponding to the first frequency), ω TO and γ LO and are the angular frequency and damping constant of the transverse optical phonon model, γ LO is the characteristic frequency of the longitudinal optical phonon model, and ω is the angular frequency.

[0081] In another embodiment of the present invention, the step of using a relative dielectric constant corresponding to the frequency of the incident light as a known parameter and applying a plurality of second relative dielectric constant models to respectively fit and obtain a plurality of relative dielectric constants of the semiconductor film at the second frequency comprises the following steps:

[0082] Taking the relative dielectric constant corresponding to the first frequency as a known parameter, each of the second relative dielectric constant models is applied to obtain the relative dielectric constant of the semiconductor film at the first sub-frequency, where the relative dielectric constant of the semiconductor film depends on ionic polarization and electronic polarization. The first sub-frequency is 10 12 Hz.

[0083] Taking the relative dielectric constant corresponding to the first sub-frequency as a known parameter, each of the second relative dielectric constant models is applied to obtain the relative dielectric constant of the semiconductor film at the second sub-frequency. The relative dielectric constant of the semiconductor film at the second sub-frequency depends on the dipole polarization, ion polarization and electron polarization. The second sub-frequency is 10 9 Hz.

[0084] Taking the relative dielectric constant corresponding to the second sub-frequency as a known parameter, each second relative dielectric constant model is applied to obtain the relative dielectric constant of the semiconductor film at the second frequency, wherein the second frequency is less than the second sub-frequency, the second sub-frequency is less than the first sub-frequency, the first sub-frequency is less than the first frequency, and the relative dielectric constant of the semiconductor film at the second frequency depends on space charge polarization, double ion polarization, ion polarization and electronic polarization. The second frequency is 10 5 Hz.

[0085] Through the above steps, the relative dielectric constant of the semiconductor film at low frequency can be gradually obtained.

[0086] As described above, there may be multiple second relative permittivity models suitable for the sample to be tested. Therefore, it is necessary to evaluate the fitting result of the selected second relative permittivity model to obtain an accurate relative permittivity.

[0087] In this embodiment, a second evaluation function is used to evaluate the accuracy of the second relative permittivity model, and the relative permittivity obtained by fitting the second relative permittivity model that meets the preset standard is selected as the relative permittivity of the semiconductor film at the second frequency. For example, the second evaluation function includes a mean absolute error function (MAE) or a determination coefficient function, and the mean absolute error function or the determination coefficient function is used to calculate the mean absolute error or the determination coefficient of each of the second relative permittivity models; the relative permittivity obtained by fitting the second relative permittivity model corresponding to the minimum mean absolute error or the maximum determination coefficient is used as the relative permittivity of the semiconductor film.

[0088] The expression of the mean absolute error function is:

[0089]

[0090] The expression of the coefficient of determination is

[0091]

[0092] In which, define y i is the standard relative dielectric constant of the sample to be tested or the value in the self-assembled database through a large amount of data measurement, To measure the value, is the measured average value.

[0093] As an example, the present invention provides a method for obtaining the piezoelectric coefficient of the semiconductor film by applying a physical model. The physical model includes a piezoelectric coefficient model, and the method for obtaining the piezoelectric coefficient of the semiconductor film by applying the physical model includes:

[0094] The piezoelectric coefficient model is used to obtain the piezoelectric coefficient d of the semiconductor film. 33 , the piezoelectric coefficient model includes the following formula:

[0095] d 33 =2Q 33 ε0ε r P s

[0096] Among them, Q 33 is the electrostrictive coefficient of the semiconductor film, ε0 is the vacuum relative dielectric constant of the semiconductor film, ε r is the relative dielectric constant of the semiconductor film, P s is the spontaneous polarization of the semiconductor film. Wherein, the relative dielectric constant of the semiconductor film has been obtained in the above steps.

[0097] As an example, the present invention provides a method for obtaining the stress of the semiconductor film by applying a physical model. The physical model includes a stress model, and the method for obtaining the stress of the semiconductor film by applying the physical model using the optical parameters of the sample to be tested as known parameters includes:

[0098] The curvature radius of the substrate is obtained according to the substrate type. The substrate includes a single layer or multiple layers. The number of layers and materials of the substrate are different, and the stress is also different. In an embodiment of the present invention, a database can be established according to the substrate type (number of layers and material type), and the database includes multiple data pairs, and the data pairs are substrates and their corresponding curvature radii. In this step, the curvature radius of the substrate can be obtained from the database according to the substrate of the sample to be tested.

[0099] The stress σ of the semiconductor film is obtained according to the stress model, and the stress model includes the following formula (Stony formula):

[0100]

[0101] Where Es is the elastic model of the substrate, t s is the thickness of the substrate, Vs is the Poisson's ratio of the substrate, Rs is the radius of curvature of the substrate, t f is the thickness of the semiconductor film, R fIt is the difference between the radius of curvature of the sample to be tested and the radius of curvature of the substrate. The thickness of the semiconductor film can be obtained through the above steps.

[0102] Please continue reading Figure 1 Step S12, repeat the above steps to obtain the measurement parameters of multiple measurement points, that is, repeat steps S10 and S11 to obtain the measurement parameters of multiple measurement points. The purpose of this step is to obtain the measurement parameters of multiple measurement points to provide data for subsequent uniformity evaluation.

[0103] Further, in this embodiment, in the step of obtaining the refractive index and extinction coefficient of the measurement point at the set wavelength or within the set wavelength range, since the first evaluation function has been used to evaluate the appropriate dispersion model at the first measurement point, in this step, the dispersion model that meets the preset standard can be directly used to fit the refractive index and extinction coefficient of multiple measurement points without the need to screen the dispersion model again. In other embodiments of the present invention, in order to further ensure data accuracy, the step of screening the dispersion model can also be performed for each measurement point.

[0104] Further, in this embodiment, in the step of using the relative dielectric constant corresponding to the first frequency as a known parameter and applying multiple second relative dielectric constant models to fit and obtain multiple relative dielectric constants of the semiconductor film at the second frequency, since the second evaluation function has been used to evaluate the suitable second relative dielectric constant model at the first measurement point, in this step, the second relative dielectric constant model that meets the preset standard can be directly used to fit and obtain the relative dielectric constants of multiple measurement points without the need to screen the second relative dielectric constant model again. In other embodiments of the present invention, in order to further ensure the accuracy of the data, the step of screening the second relative dielectric constant model can also be performed for each measurement point.

[0105] Please continue reading Figure 1 Step S13, uniformity evaluation is performed on the same measurement parameter of multiple measurement points. In this step, the obtained measurement parameters can be plotted into a topographic map, so as to evaluate the uniformity of the semiconductor film according to the distribution of the measurement parameters on the topographic map.

[0106] For example, the thickness obtained at multiple measurement points can be plotted as a topographic map according to their location, see Figure 2 , which is a thickness distribution diagram of lead zirconate titanate film on the surface of a 3-inch wafer. From this diagram, we can clearly see the thickness distribution and uniformity of the lead zirconate titanate film; please refer to Figure 3 , which is a relative dielectric constant distribution diagram of lead zirconate titanate film on the surface of a 3-inch wafer. From this diagram, we can clearly see the distribution of the relative dielectric constant of the lead zirconate titanate film and the uniformity of the relative dielectric constant distribution; please refer to Figure 4, which is a piezoelectric coefficient distribution diagram of lead zirconate titanate film on a 3-inch wafer surface. From this diagram, we can clearly see the distribution of the piezoelectric coefficient of the lead zirconate titanate film and the uniformity of the piezoelectric coefficient distribution; please refer to Figure 5 , which is a stress distribution diagram of the lead zirconate titanate film on the surface of a 3-inch wafer. From this diagram, we can clearly see the stress distribution and uniformity of the lead zirconate titanate film.

[0107] In the detection method of the present invention, the relative dielectric constant ranges from 0.1 to 2000, the dielectric loss ranges from 0 to 10, the piezoelectric constant ranges from 1 to 1000 pm / V, the semiconductor film thickness ranges from 100 to 6000 nm, and the stress ranges from 10 to 2000 MPa.

[0108] The semiconductor thin film uniformity detection method provided by the present invention can measure optical parameters using optical methods, and then use the optical parameters as known quantities to obtain the measurement parameters of the semiconductor thin film according to the physical model, thereby realizing the evaluation of the uniformity of the measurement parameters. The detection method of the present invention can realize non-destructive measurement of semiconductor thin films, and the obtained measurement parameters are not single, which meets diversified needs.

[0109] The present invention also provides a system for realizing the above-mentioned semiconductor film uniformity detection. Figure 6 , which is a schematic diagram of the structure of the system of the present invention, the system includes a sample stage 1, an optical detection unit 2, an analysis unit 3, a physical model unit 4 and an evaluation unit 5.

[0110] The sample stage 1 is used to place the sample to be tested, and the sample to be tested includes a substrate and a semiconductor film arranged on the substrate. The sample stage 1 can rotate and move along a set direction. The sample stage can place samples of different sizes, such as 3-inch, 4-inch, 6-inch, 8-inch, 12-inch wafers, square, rectangular or other irregularly shaped films. The rotation mode of the sample stage 1 is rotational motion in a plane or translation along a set direction (such as any one or two directions in the X direction and the Y direction). Among them, the rotation speed can be set according to needs. For example, in some embodiments, the rotation speed ranges from 0 to 40 deg / s. The driving mode of the sample stage can be manual or automatic, and can be set according to needs. For example, for regular shapes such as wafers and rectangular or square semiconductor films, it can be set to automatic movement; for irregularly shaped semiconductor films, it can be manually adjusted according to the shape and size of the semiconductor film to obtain the required measurement points.

[0111] In this embodiment, the system further includes a rotating device 6 for driving the sample stage to rotate, a sliding device 7 for driving the sample stage 1 to move linearly, and a connecting rod 8 connecting the sample stage 1 , the rotating device 6 and the sliding device 7 .

[0112] The optical detection unit 2 is used to provide incident light and obtain ellipsometric parameters of reflected light at the measuring point of the sample to be measured, and / or form a reflected light array and receive the reflected light array information. The ellipsometric parameters include the amplitude ratio and phase difference of the reflected light.

[0113] In this embodiment, the optical detection unit 2 includes a light source 20 , a polarizer 21 , an analyzer 22 , a linear CCD 23 , and a receiver 24 .

[0114] The light source 20 is used to provide incident light. The polarizer 21 is used to convert the incident light into polarized light, and the polarized light is incident on the measurement point at a set incident angle. The analyzer 22 is used to detect the polarized light signal of the reflected light of the sample to be measured; the linear CCD 23 is used to receive the polarized light signal and form a reflected light array; the receiver 24 is used to obtain the ellipsometric parameters of the polarized light signal and / or the reflected light array information, and send them to the analysis unit 3.

[0115] The analysis unit 3 is used to obtain the optical parameters of the measurement point of the sample to be tested at a set wavelength or a set wavelength range according to the ellipsometric parameters and / or the reflected light array information, and the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be tested. In this embodiment, the analysis unit 3 obtains the refractive index and extinction coefficient of the measurement point of the sample to be tested at a set wavelength or a set wavelength range according to the ellipsometric parameters, and obtains the curvature radius of the measurement point of the sample to be tested at a set wavelength or a set wavelength range according to the reflected light array information.

[0116] Further, in some embodiments, the analysis unit 3 includes a dispersion model unit 30 and a first evaluation function unit 31, the dispersion model unit 30 includes multiple dispersion models, the first evaluation function unit 31 includes a first evaluation function, and the analysis unit 3 is used to use the ellipsometric parameters as known parameters, apply multiple dispersion models to respectively fit to obtain initial values ​​of multiple refractive indices and extinction coefficients, and use the first evaluation function to evaluate the dispersion model fitting results, and select the initial values ​​of the refractive index and extinction coefficient obtained by fitting the dispersion model that meet preset standards as the optical parameters.

[0117] The physical model unit 4 is used to apply the physical model to obtain the measurement parameters of the semiconductor film, wherein the measurement parameters include the relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film. The physical model unit 4 obtains the optical parameters from the analysis unit 3, and uses the optical parameters as known quantities to select an appropriate physical model to obtain the corresponding measurement parameters.

[0118] Further, in some embodiments, the physical model unit 4 includes a thickness query unit 40, and the thickness query unit 40 is used to use the wavelength of the incident light, the incident angle and the refractive index of the semiconductor film as known parameters of the thickness query unit 40 to obtain a comparison table of ellipsometric parameters, thickness and refractive index, and use the ellipsometric parameters of the incident light at the measuring point as query parameters of the thickness query unit 40 to obtain the thickness of the semiconductor film in the comparison table.

[0119] Further, in some embodiments, the physical model unit 4 includes a relative dielectric constant model unit 41 and a second evaluation function unit 42, the relative dielectric constant model unit 41 is used to obtain the relative dielectric constant of the semiconductor film according to the first relative dielectric constant model and the second relative dielectric constant model, the second evaluation function unit 42 is used to evaluate the accuracy of the second relative dielectric constant model, and the physical model unit 4 is also used to select the relative dielectric constant obtained by fitting the second relative dielectric constant model that meets the preset standard as the relative dielectric constant of the semiconductor film.

[0120] Furthermore, in some embodiments, the physical model unit 4 includes a piezoelectric coefficient model unit 43, and the piezoelectric coefficient model unit 43 is used to obtain the piezoelectric coefficient of the semiconductor film by adopting a piezoelectric coefficient model.

[0121] Furthermore, in some embodiments, the physical model unit 4 includes a stress model unit 44, and the stress model unit 44 is used to obtain the stress of the semiconductor film by using a stress model.

[0122] The evaluation unit 5 is used to evaluate the uniformity of the same measurement parameter at multiple measurement points. For example, the evaluation unit 5 can draw the same measurement parameter at multiple measurement points into a topographic map, thereby evaluating the uniformity of the semiconductor film according to the distribution of the measurement parameter on the topographic map.

[0123] The system provided by the present invention can measure optical parameters using optical methods, and then use the optical parameters as known quantities to obtain measurement parameters of semiconductor films according to physical models, thereby realizing the evaluation of the uniformity of the measurement parameters. The system of the present invention can realize non-destructive measurement of semiconductor films, and the measurement parameters obtained are not single, meeting diverse needs.

[0124] The detection method and system of the present invention are further explained below by taking a 3-inch lead zirconate titanate piezoelectric wafer as an example.

[0125] Example 1: Testing the thickness uniformity of a 3-inch lead zirconate titanate piezoelectric wafer sample.

[0126] (1) Place a 3-inch wafer on a 3-inch sample holder, and fix the sample holder on the sample stage.

[0127] (2) A light wave with a wavelength range of 400 nm to 1600 nm is selected, an incident angle of 75° is selected, and the center point of the wafer is selected as the first measurement point. The optical detection unit obtains the variation of the ellipsometric parameters of the center point of the sample to be measured with the wavelength, that is, the variation of the amplitude ratio and the phase difference with the wavelength.

[0128] (3) Taking the wavelength of the incident light source, the incident angle, and the refractive index of the semiconductor film as known quantities, the relationship table between the amplitude ratio and the phase difference and the thickness is obtained from the physical model unit to obtain the thickness of the semiconductor film at the measurement point.

[0129] (4) Rotate the sample stage to test the ellipsometric parameters at multiple measurement points and repeat steps (2) to (3).

[0130] (5) The thickness of multiple measurement points is used as data to evaluate the thickness uniformity of the sample to be tested. The thickness distribution diagram is as follows: Figure 2 shown.

[0131] Example 2: Testing the relative dielectric constant and piezoelectric coefficient uniformity of a 3-inch lead zirconate titanate piezoelectric wafer sample.

[0132] (1) Place a 3-inch wafer on a 3-inch sample holder, and fix the sample holder on the sample stage.

[0133] (2) Select a light wave with a wavelength of 400nm-1600nm, select an incident angle of 75°, and select the center point of the wafer as the first measurement point. The optical detection unit obtains the ellipsometric parameters of the center point of the sample to be measured, that is, the change of the amplitude ratio and phase difference with the wavelength.

[0134] (3) According to the material type of the sample to be tested, the Tauc-Lorentz model is used to fit the data to obtain the refractive index and extinction coefficient of the sample to be tested at different wavelengths.

[0135]

[0136] ε2=0,E≤E g

[0137] (4) The root mean square error was used to calculate the matching degree of the fit, and the calculated MES was 5.52; the goodness of fit determination coefficient R was calculated 2 =0.986, to test the dispersion model.

[0138] (5) According to the data in step (3), the refractive index and extinction coefficient at a wavelength of 632.8 nm are selected to calculate the relative dielectric constant at ultra-high frequency, and then the relative dielectric constant contributed by different mechanisms is calculated to obtain the relative dielectric constant at low frequency. The relative dielectric constant and determination coefficient at 10 kHz calculated using different models are:

[0139] Semi-quantum model: 530; 0.92

[0140] Relaxation oscillation model: 150; 0.54

[0141] Debye relaxation model: 170; 0.61

[0142] Damped oscillator model: 320; 0.77

[0143] Pseudoharmonic model: 210; 0.65

[0144] The fitting result of the half-quantum model with the largest determination coefficient is selected as the relative dielectric constant of the semiconductor film at 10 kHz.

[0145] Furthermore, the relative dielectric constant of the sample under test was measured using a probe method digital bridge at 10 kHz and was found to be 560, which is close to the fitting result of the semi-quantum model, and further illustrates that the method of the present invention has high accuracy.

[0146] (6) The transverse piezoelectric coefficient at this point is calculated using the following formula, and the value is 420pC / N.

[0147] d 33 =2Q 33 ε0ε r P s

[0148] (7) Rotate the sample stage, test the ellipsometric parameters at multiple measurement points, repeat steps (2)-(5), and obtain the uniformity of the low-frequency relative dielectric constant and the uniformity of the lateral piezoelectric coefficient, such as Figure 3 and Figure 4 shown.

[0149] Example 3: Testing the stress uniformity of a 3-inch lead zirconate titanate piezoelectric wafer sample.

[0150] (1) Place a 3-inch wafer on a 3-inch sample holder, and fix the sample holder on the sample stage.

[0151] (2) The light source is aligned with the center of the wafer, and light with a wavelength of 670 nm is selected to be reflected by the thin film and obtained by the linear array CCD to obtain a reflection array. The radius of curvature of the measurement point of the sample to be measured is received by the receiver, which is 37.09 m.

[0152] (3) The curvature radius of the base of the sample to be tested is retrieved from the database to obtain the difference between the curvature radius of the sample to be tested and the curvature radius of the base. Here, the curvature radius of the base is selected as -340.82m, the stress type is tensile stress, and the stress at the measuring point is calculated to be 225MPa by the Stony formula.

[0153] (4) Rotate the sample stage to test the stress at multiple measurement points to obtain the stress distribution and stress uniformity of the 3-inch lead zirconate titanate piezoelectric wafer, such as Figure 5 shown.

[0154] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for nondestructive testing of semiconductor thin film uniformity, characterized in that: The sample to be tested includes a substrate and a semiconductor film arranged on the surface of the substrate, and the method includes: The incident light is incident on the measuring point on the surface of the sample to be measured at a set incident angle, and the optical parameters of the measuring point at a set wavelength or a set wavelength range are obtained, wherein the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be measured; Taking the optical parameters of the sample to be measured as known parameters, applying the physical model to obtain the measurement parameters of the semiconductor film, wherein the measurement parameters include the relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film; Repeat the above steps to obtain the measurement parameters of multiple measurement points; Perform uniformity evaluation on the same measurement parameter at multiple measurement points. The incident light is incident on the measuring point on the surface of the sample to be measured at a set incident angle, and in the step of obtaining the optical parameters of the measuring point at a set wavelength or a set wavelength range, the frequency range of the incident light is a first frequency, and the relative dielectric constant of the semiconductor film at the first frequency depends on the electron polarization; The physical model includes a first relative dielectric constant model and a second relative dielectric constant model. The method of using the optical parameters of the sample to be tested as known parameters and applying the physical model to obtain the relative dielectric constant of the semiconductor film includes: The relative dielectric constant ε1 of the semiconductor film at the first frequency is obtained according to the first relative dielectric constant model, wherein the first relative dielectric constant model includes the following formula: ε1=n 2 -k 2 Wherein, n is the refractive index of the semiconductor film, and k is the extinction coefficient of the semiconductor film; Taking the relative dielectric constant corresponding to the first frequency as a known parameter, applying a plurality of second relative dielectric constant models to respectively fit and obtain a plurality of relative dielectric constants of the semiconductor film at a second frequency, wherein the second frequency is less than the first frequency; The accuracy of the second relative permittivity model is evaluated by using a second evaluation function, and the relative permittivity obtained by fitting the second relative permittivity model that meets a preset standard is selected as the relative permittivity of the semiconductor film at the second frequency. The second relative permittivity model includes at least two of a half-quantum model, a relaxation oscillation model, a Debye relaxation model, a damped resonator model, and a pseudoharmonic model. The step of using a relative dielectric constant corresponding to the frequency of the incident light as a known parameter and applying a plurality of second relative dielectric constant models to respectively fit and obtain a plurality of relative dielectric constants of the semiconductor film at the second frequency comprises: Taking the relative dielectric constant corresponding to the first frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the first sub-frequency, wherein the relative dielectric constant of the semiconductor film at the first sub-frequency depends on ionic polarization and electronic polarization; Taking the relative dielectric constant corresponding to the first sub-frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the second sub-frequency, wherein the relative dielectric constant of the semiconductor film at the second sub-frequency depends on the dipole ion polarization, the ion polarization and the electron polarization; Taking the relative dielectric constant corresponding to the second sub-frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the second frequency, wherein the second frequency is less than the second sub-frequency, the second sub-frequency is less than the first sub-frequency, the first sub-frequency is less than the first frequency, and the relative dielectric constant of the semiconductor film at the second frequency depends on space charge polarization, double ion polarization, ion polarization and electronic polarization, The second evaluation function includes a mean absolute error function or a determination coefficient function, and the step of selecting the relative permittivity obtained by fitting the second relative permittivity model that meets the preset standard as the relative permittivity of the semiconductor film at the second frequency includes: Applying a mean absolute error function or a coefficient of determination function to calculate a mean absolute error or a coefficient of determination for each of the second relative permittivity models; The relative dielectric constant obtained by fitting the second relative dielectric constant model corresponding to the minimum mean absolute error or the maximum determination coefficient is used as the relative dielectric constant of the semiconductor film. Repeat the above steps to obtain the measurement parameters of multiple measurement points, directly use the second relative dielectric constant model that meets the preset standard to fit the relative dielectric constants of multiple measurement points, The method further includes using the optical parameters of the sample to be tested as known parameters and applying a physical model to obtain the dielectric loss of the semiconductor film, including: applying the following formula to obtain the dielectric loss ε2 of the semiconductor film: ε2=2nk Wherein, n is the refractive index of the semiconductor film, k is the extinction coefficient of the semiconductor film, The physical model includes a piezoelectric coefficient model. The method of using the optical parameters of the sample to be tested as known parameters and applying the physical model to obtain the piezoelectric coefficient of the semiconductor film includes: The piezoelectric coefficient model is used to obtain the piezoelectric coefficient d of the semiconductor film. 33 , the piezoelectric coefficient model includes the following formula: d 33 =2Q 33 ε0ε r P s Among them, Q 33 is the electrostrictive coefficient of the semiconductor film, ε0 is the vacuum relative dielectric constant of the semiconductor film, ε r is the relative dielectric constant of the semiconductor film, P s It is the spontaneous polarization of the semiconductor film.

2. The method for nondestructive testing of semiconductor thin film uniformity according to claim 1, characterized in that: The method for obtaining the optical parameters of the measuring point at a set wavelength or within a set wavelength range includes: Obtaining ellipsometric parameters of the incident light at the measuring point; Using the ellipsometric parameters as known parameters, multiple dispersion models are applied to respectively fit and obtain initial values ​​of multiple refractive indices and extinction coefficients; A first evaluation function is used to evaluate the dispersion model fitting result, and initial values ​​of the refractive index and the extinction coefficient obtained by the dispersion model fitting that meet preset standards are selected as the optical parameters.

3. The method for nondestructive testing of semiconductor thin film uniformity according to claim 2, characterized in that: Repeat the above steps to obtain the measurement parameters of multiple measurement points, and directly use the dispersion model that meets the preset standard to fit and obtain the refractive index and extinction coefficient of multiple measurement points.

4. The method for nondestructive testing of semiconductor thin film uniformity according to claim 2, characterized in that: The dispersion model includes at least two of the following: NK model, Cauchy model, Cauchy index model, Forouhi-Bloomer model, Lorentz model, Sellmeier model, effective medium approximation model, and Tauc-Lorentz model.

5. The method for nondestructive testing of semiconductor thin film uniformity according to claim 2, characterized in that: The first evaluation function includes a root mean square error evaluation function, and the step of using the first evaluation function to evaluate the dispersion model fitting result, and selecting the initial values ​​of the refractive index and the extinction coefficient obtained by the dispersion model fitting that meet the preset standard as the optical parameters includes: The root mean square error (RMS) is obtained by using a root mean square error (RMS) evaluation function on the fitting result of the dispersion model; The initial values ​​of the refractive index and the extinction coefficient obtained by fitting the dispersion model corresponding to the minimum root mean square error are used as the optical parameters.

6. The method for nondestructive testing of semiconductor thin film uniformity according to claim 2, characterized in that: The method of obtaining the thickness of the semiconductor film by applying a physical model using the optical parameters of the sample to be tested as known parameters includes: Using the wavelength of incident light, the incident angle and the refractive index of the semiconductor film as known parameters of the physical model, a comparison table of ellipsometric parameters, thickness and refractive index is obtained; The ellipsometric parameter of the incident light at the measuring point is used as a query parameter of the physical model, and the thickness of the semiconductor film is obtained in the comparison table.

7. The method for nondestructive testing of semiconductor thin film uniformity according to claim 1, characterized in that: The physical model includes a stress model. The method of using the optical parameters of the sample to be tested as known parameters and applying the physical model to obtain the stress of the semiconductor film includes: Acquire the curvature radius of the substrate according to the substrate type; The stress σ of the semiconductor film is obtained according to the stress model, and the stress model includes the following formula: Among them, E S is the elastic model of the substrate, t s is the thickness of the substrate, V s is the Poisson's ratio of the basis, R s is the radius of curvature of the base, t f is the thickness of the semiconductor film, R f It is the difference between the radius of curvature of the sample to be tested and the radius of curvature of the substrate.

8. A system for realizing nondestructive testing of semiconductor thin film uniformity according to any one of claims 1 to 7, characterized in that: include: A sample stage, used for placing a sample to be tested, wherein the sample to be tested includes a substrate and a semiconductor film arranged on the substrate, and the sample stage can rotate and move along a set direction; An optical detection unit, used for providing incident light and obtaining ellipsometric parameters of reflected light at a measuring point of the sample to be measured, and / or forming a reflected light array and receiving information of the reflected light array; An analysis unit, used for obtaining optical parameters of the measuring point of the sample to be measured at a set wavelength or a set wavelength range according to the ellipsometric parameters and / or the reflected light array information, wherein the optical parameters include the refractive index and extinction coefficient of the semiconductor film and / or the curvature radius of the sample to be measured; A physical model unit, used for applying a physical model to obtain measurement parameters of the semiconductor film, wherein the measurement parameters include relative dielectric constant, piezoelectric coefficient, thickness and stress of the semiconductor film; an evaluation unit, used for evaluating the uniformity of the same measurement parameter at multiple measurement points, wherein incident light is incident on the measurement point on the surface of the sample to be measured at a set incident angle, and in the step of obtaining the optical parameters of the measurement point at a set wavelength or a set wavelength range, the frequency range of the incident light is a first frequency, and the relative dielectric constant of the semiconductor film at the first frequency depends on the electronic polarization; The physical model includes a first relative dielectric constant model and a second relative dielectric constant model. The method of using the optical parameters of the sample to be tested as known parameters and applying the physical model to obtain the relative dielectric constant of the semiconductor film includes: The relative dielectric constant ε1 of the semiconductor film at the first frequency is obtained according to the first relative dielectric constant model, wherein the first relative dielectric constant model includes the following formula: ε1=n 2 -k 2 Wherein, n is the refractive index of the semiconductor film, and k is the extinction coefficient of the semiconductor film; Taking the relative dielectric constant corresponding to the first frequency as a known parameter, applying a plurality of second relative dielectric constant models to respectively fit and obtain a plurality of relative dielectric constants of the semiconductor film at a second frequency, wherein the second frequency is less than the first frequency; The accuracy of the second relative permittivity model is evaluated by using a second evaluation function, and the relative permittivity obtained by fitting the second relative permittivity model that meets a preset standard is selected as the relative permittivity of the semiconductor film at the second frequency. The second relative permittivity model includes at least two of a half-quantum model, a relaxation oscillation model, a Debye relaxation model, a damped resonator model, and a pseudoharmonic model. The step of using a relative dielectric constant corresponding to the frequency of the incident light as a known parameter and applying a plurality of second relative dielectric constant models to respectively fit and obtain a plurality of relative dielectric constants of the semiconductor film at the second frequency comprises: Taking the relative dielectric constant corresponding to the first frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the first sub-frequency, wherein the relative dielectric constant of the semiconductor film at the first sub-frequency depends on ionic polarization and electronic polarization; Taking the relative dielectric constant corresponding to the first sub-frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the second sub-frequency, wherein the relative dielectric constant of the semiconductor film at the second sub-frequency depends on the dipole ion polarization, the ion polarization and the electron polarization; Taking the relative dielectric constant corresponding to the second sub-frequency as a known parameter, applying each of the second relative dielectric constant models to obtain the relative dielectric constant of the semiconductor film at the second frequency, wherein the second frequency is less than the second sub-frequency, the second sub-frequency is less than the first sub-frequency, the first sub-frequency is less than the first frequency, and the relative dielectric constant of the semiconductor film at the second frequency depends on space charge polarization, double ion polarization, ion polarization and electronic polarization, The second evaluation function includes a mean absolute error function or a determination coefficient function, and the step of selecting the relative permittivity obtained by fitting the second relative permittivity model that meets the preset standard as the relative permittivity of the semiconductor film at the second frequency includes: Applying a mean absolute error function or a coefficient of determination function to calculate a mean absolute error or a coefficient of determination for each of the second relative permittivity models; The relative dielectric constant obtained by fitting the second relative dielectric constant model corresponding to the minimum mean absolute error or the maximum determination coefficient is used as the relative dielectric constant of the semiconductor film. Repeat the above steps to obtain the measurement parameters of multiple measurement points, directly use the second relative dielectric constant model that meets the preset standard to fit the relative dielectric constants of multiple measurement points, The method further includes using the optical parameters of the sample to be tested as known parameters and applying a physical model to obtain the dielectric loss of the semiconductor film, including: applying the following formula to obtain the dielectric loss ε2 of the semiconductor film: ε2=2nk Wherein, n is the refractive index of the semiconductor film, k is the extinction coefficient of the semiconductor film, The physical model includes a piezoelectric coefficient model. The method of using the optical parameters of the sample to be tested as known parameters and applying the physical model to obtain the piezoelectric coefficient of the semiconductor film includes: The piezoelectric coefficient model is used to obtain the piezoelectric coefficient d of the semiconductor film. 33 , the piezoelectric coefficient model includes the following formula: d 33 =2Q 33 ε0ε r P s Among them, Q 33 is the electrostrictive coefficient of the semiconductor film, ε0 is the vacuum relative dielectric constant of the semiconductor film, ε r is the relative dielectric constant of the semiconductor film, P s It is the spontaneous polarization of the semiconductor film.

9. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The optical detection unit comprises: A light source, for providing incident light; A polarizer, used for converting the incident light into polarized light, wherein the polarized light is incident on the measuring point at a set incident angle; A polarizer, used to detect the polarized light signal of the reflected light of the sample to be tested; A linear CCD, used for receiving the polarized light signal and forming a reflected light array; The receiver is used to obtain the ellipsometric parameters of the polarized light signal and / or the reflected light array information, and send them to the analysis unit.

10. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The analysis unit includes a dispersion model unit and a first evaluation function unit, the dispersion model unit includes multiple dispersion models, the first evaluation function unit includes a first evaluation function, the analysis unit is used to use the ellipsometric parameters as known parameters, apply multiple dispersion models to respectively fit to obtain initial values ​​of multiple refractive indices and extinction coefficients, and use the first evaluation function to evaluate the dispersion model fitting results, and select the initial values ​​of the refractive index and extinction coefficient obtained by fitting the dispersion model that meet preset standards as the optical parameters.

11. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The physical model unit includes a thickness query unit, which is used to use the wavelength of the incident light, the incident angle and the refractive index of the semiconductor film as known parameters of the thickness query unit to obtain a comparison table of ellipsometric parameters, thickness and refractive index, and use the ellipsometric parameters of the incident light at the measuring point as the query parameters of the thickness query unit to obtain the thickness of the semiconductor film in the comparison table.

12. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The physical model unit includes a relative dielectric constant model unit and a second evaluation function unit. The relative dielectric constant model unit is used to obtain the relative dielectric constant of the semiconductor film according to the first relative dielectric constant model and the second relative dielectric constant model. The second evaluation function unit is used to evaluate the accuracy of the second relative dielectric constant model. The physical model unit is also used to select the relative dielectric constant obtained by fitting the second relative dielectric constant model that meets the preset standards as the relative dielectric constant of the semiconductor film.

13. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The physical model unit includes a piezoelectric coefficient model unit, and the piezoelectric coefficient model unit is used to obtain the piezoelectric coefficient of the semiconductor film by adopting a piezoelectric coefficient model.

14. The system for nondestructive testing of semiconductor thin film uniformity according to claim 8, characterized in that: The physical model unit includes a stress model unit, and the stress model unit is used to obtain the stress of the semiconductor film by adopting a stress model.

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