Method and equipment for measuring thickness of thin film on suede silicon substrate

Abstract

The invention relates to the technical field of film thickness measurement, in particular to a method and equipment for measuring the thickness of a film on a suede silicon substrate, and the method comprises the following steps: enabling at least one light beam to vertically enter the surface of a film sample, and receiving a reflected light beam; adjusting the position of the film sample to enable the film sample to be in a proper test coordinate and angle; setting a position where an incident light beam enters the surface of the film sample for the first time as a first position and another position where the incident light beam enters the surface of the film sample after being reflected as a second position under proper test coordinates and angles, and determining incident light intensity and effective incident light intensity at the first position; and calculating the reflectivity, transmissivity and reflected light intensity of the light beam at the first position, calculating the theoretical reflectivity and the actual reflectivity at the second position on the basis, and finally substituting the theoretical reflectivity and the actual reflectivity into a theoretical formula to obtain the thickness of the to-be-measured film. The method has the effect of improving the accuracy of the measurement result.

Description

Technical Field

[0001] The present application relates to the technical field of thin film thickness measurement, and in particular to a method and device for measuring the thickness of a thin film on a textured silicon substrate. Background Art

[0002] At present, the field of optical measurement technology is developing rapidly, especially in the semiconductor manufacturing and photovoltaic industries, where accurate measurement of film thickness is particularly important. This measurement is not only related to product quality, but also can significantly improve production process efficiency and reduce costs. Figure 1 The film thickness measurement method is usually to use a light source to emit incident light to the film sample 6, so that the incident light is perpendicular to the film sample 6 and is reflected by the upper and lower surfaces of the film sample 6 to generate two beams of reflected light. When the two beams of reflected light meet in space, they will interfere due to the same amplitude and frequency, and then the film thickness is measured by calculating the reflectivity. Specifically, the reflectivity can be calculated according to the Fresnel formula. For vertical incidence, the reflection coefficient r and the transmission coefficient t can be expressed as follows: Among them, r and t are complex numbers, containing amplitude and phase information. n1 is the refractive index of air, and n2 is the refractive index of the film. Through r and t, the reflectivity can be calculated, and the film thickness can be calculated through the reflectivity: Regarding the above-mentioned related technologies: In the photovoltaic industry, in order to improve the light trapping of silicon wafers, silicon wafers are usually treated with alkali to achieve texturing, and finally a pyramid-shaped velvet surface is obtained. In the subsequent process, other thin films need to be deposited on the velvet silicon wafer. Since the velvet silicon surface has significant roughness, it does not conform to the smooth surface assumed by the Fresnel formula. Therefore, it is easy to have inaccurate measurement results. Summary of the invention

[0003] In order to improve the accuracy of the measurement results, the present application provides a method and device for measuring the thickness of a thin film on a textured silicon substrate.

[0004] In the first aspect, the present application provides a method for measuring the thickness of a thin film on a textured silicon substrate, which adopts the following technical solution: A method for measuring the thickness of a thin film on a suede silicon substrate comprises the following steps: At least one light beam is vertically incident on the surface of the film sample and a reflected light beam is received; Adjusting the position of the film sample so that the film sample is at a suitable test coordinate and angle; Under appropriate test coordinates and angles, the position where the incident light beam first enters the surface of the thin film sample is the first position, and the other position where the incident light beam enters the surface of the thin film sample after being reflected is the second position, and the incident light intensity and the effective incident light intensity at the first position are determined; The reflectivity, transmittance, and reflected light intensity of the light beam at the first position are calculated, and based on this, the theoretical reflectivity and actual reflectivity at the second position are calculated, and finally substituted into the theoretical formula to obtain the thickness of the film to be measured.

[0005] By adopting the above technical solution, the reflectivity at the first position and the second position is calculated, and then the result is substituted into the theoretical formula to calculate the thickness of the film to be measured, thereby achieving accurate analysis and processing of complex reflection and refraction phenomena, thereby facilitating accurate measurement of the film thickness of samples with complex surface morphology such as suede silicon, which is beneficial to improve the accuracy of the measurement results.

[0006] Optionally, the incident light intensity at the first position is set to I 0 , the effective incident light intensity is I 0_cal , then the calculation formula for the effective incident light intensity is as follows: I 0_cal =0.25·I 0 .

[0007] Optionally, the reflectivity of the light beam at the first position is calculated, and the specific steps are as follows: According to the Fresnel formula and the transmission matrix method, the Fresnel formula is: And n1, n2, θ1 and θ2 satisfy the following relationship: The transfer matrix method is: M total =M 1 ·M 2 ·…·M N Among them, r s is the reflection coefficient of s wave, r p is the reflection coefficient of the p-wave, n1 is the refractive index of the incident medium, n2 is the refractive index of the transmission medium, θ1 is the incident angle, θ2 is the refraction angle, M i is the characteristic matrix of each layer of the multilayer film, cos(δ i )and These elements describe the phase and amplitude changes of light waves in a medium; and cos(δ i) also describes the phase and amplitude changes, but corresponds to different polarizations or propagation directions; δ i is the phase thickness, which describes the phase difference accumulated when the light wave propagates in the medium; d i is the thickness of the film, λ is the wavelength, q i is the wave vector component, M total is the transmission matrix of the entire multilayer film, R 1 is the reflectivity at the first position.

[0008] By adopting the above technical solution and using the Fresnel formula and the transfer matrix method to calculate the reflectivity and transmittance of the light beam at the first position, it is possible to accurately analyze complex reflection and refraction phenomena, thereby improving the accuracy of thin film thickness measurement on a suede silicon substrate.

[0009] Optionally, a calculation formula for calculating the intensity of the reflected light at the first position is as follows: I R1 =R 1 I 0_cal Among them, I R1 is the reflected light intensity at the first position.

[0010] Optionally, the Fresnel formula and the transfer matrix method may be encapsulated as a function: f(param, x, bound), then the calculation formulas for the theoretical reflectivity and the actual reflectivity at the second position are as follows: Among them, param is the parameter, x is the thickness value of each layer, bound is the range of the thickness value of each layer, R 2_theory is the theoretical reflectivity, I R_exp is the reflected light intensity actually measured at the second position, is the reflectivity calculated at the second position, and θ3 is the incident angle of the incident light at the second position.

[0011] Optionally, the theoretical formula is: Among them, lamb start is the starting position of the calculated wavelength, lamb end is the calculated wavelength end position, where the specific step size is related to the parameter settings of the spectrometer and the accuracy required for calculation. Through the calculation of the above formula, a function can be obtained to evaluate the similarity between the calculated reflectivity curve and the theoretical reflectivity curve. Then, all thickness values ​​within the thickness range are traversed for calculation. Each thickness value can get a corresponding Δr value. All Δr are combined to obtain an array Δr about all thickness values. list, take the minimum value, and the thickness value corresponding to the minimum value is the film thickness.

[0012] Optionally, θ3=180°-3·θ1.

[0013] In a second aspect, the present application provides a device for measuring the thickness of a thin film on a textured silicon substrate, which is used to implement the above-mentioned method for measuring the thickness of a thin film on a textured silicon substrate, and adopts the following technical solution: A device for measuring the thickness of a thin film on a suede silicon substrate, comprising: light source; Two spectrometers are provided, one of which is connected to an incident light probe via an optical fiber, and the incident light probe is connected to the light source via an optical fiber, and the other spectrometer is connected to a reflected light probe via an optical fiber, and the light source can emit a light beam through the incident light probe; A sample moving stage, on which a thin film sample is placed, and the sample moving stage can adjust the angle and position of the thin film sample; The lower computer is connected to the two spectrometers respectively.

[0014] By adopting the above technical solution, when it is necessary to measure the thickness of the film, the film sample is first placed on the sample moving table, and then the light source is started, so that the incident light probe emits light and the light is vertically incident on the surface of the film sample. At this time, the reflected light probe receives the reflected light and transmits the received light signal to the spectrometer, so that the spectrometer can obtain spectral data and transmit the spectral data to the lower computer. In this process, the sample moving table can drive the film sample to rotate horizontally by a certain angle, and the spectrometer can collect signals after each rotation of the film sample by a certain angle, so that the lower computer can process the spectral data to find the test angle and test coordinates corresponding to the maximum value, and then calculate the thickness of the film to be measured based on the data measured at the test angle and test coordinates.

[0015] Optionally, it comprises a box, and the light source, the incident light probe, the reflected light probe and the sample moving stage are respectively arranged in the box.

[0016] By adopting the above technical solution, the light source, incident light probe, reflected light probe, and sample moving stage are integrated into a box to form a sealed structure, which effectively eliminates the interference of external light and improves the measurement accuracy and stability.

[0017] Optionally, the angle between the incident light probe and the horizontal plane of the thin film sample is 90 degrees, and the angle between the reflected light probe and the horizontal plane of the thin film sample is 50-52 degrees.

[0018] In summary, the present application includes at least one of the following beneficial technical effects: 1. By constructing a special optical model and using advanced calculation methods, the accurate analysis and processing of complex reflection and refraction phenomena are achieved, which facilitates the accurate measurement of the film thickness on the suede silicon surface, thereby improving the accuracy and reliability of the measurement; 2. By integrating the light source, spectrometer, probe and sample moving platform into one box, the interference of external light is effectively eliminated and the measurement accuracy is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of reflection of incident light vertically incident on a thin film sample in the related art.

[0020] Figure 2 It is a schematic diagram of the overall structure of a device for measuring the thickness of a thin film on a suede silicon substrate in an embodiment of the present application.

[0021] Figure 3 It is a schematic diagram of reflection and refraction of an incident light beam on a thin film sample in an embodiment of the present application.

[0022] Figure 4 It is a schematic diagram of partial reflection and refraction of an incident light beam on a thin film sample in an embodiment of the present application.

[0023] Description of reference numerals: 1. Spectrometer; 11. Incident light probe; 12. Reflected light probe; 2. Lower computer; 3. Light source; 31. Incident light beam; 32. First reflected light; 33. Second reflected light; 34. Third reflected light; 35. Fourth reflected light; 36. Fifth reflected light; 37. Sixth reflected light; 4. Sample moving stage; 5. Box; 6. Thin film sample; 61. First position; 62. Second position. DETAILED DESCRIPTION

[0024] The following is combined with Figure 1-4 This application is described in further detail.

[0025] The embodiment of the present application discloses a method for measuring the thickness of a thin film on a textured silicon substrate.

[0026] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] Reference Figure 2 , a method for measuring the thickness of a thin film on a suede silicon substrate, comprising the following steps: Before measuring thickness, you need to prepare first. The specific steps are as follows: A spectrometer 1 is used to collect standard spectrum data and dark spectrum data, and another spectrometer is used to collect dark spectrum data, and the collected data are uploaded to the lower computer 2. In this process, the test coordinates and test angles of the thin film sample 6 are continuously adjusted, and the spectrum signal is analyzed by the lower computer 2 to find the test coordinates and test angles corresponding to the maximum value.

[0028] Import the film optical parameters into the lower computer 2. The specific steps are as follows: According to the film structure constructed by the user, derive the optical parameters of each layer, including the wavelength array lamb, the film complex refractive index array nk_list, and the array of nk_list contains the relationship between the wavelength and complex refractive index of each layer of material. Similarly, the thickness array d_list and the thickness range array d_range_list are obtained. The following is an example of a specific optical parameter: lamb = [200 300 ... 1100]; nk_list=[[2.31+0.57j 1.55+0.j][2.18+0.03j 1.51+0.j] ……[1.30+0.01j 1.44+0.j]]; d_list = [200 200]; d_range_list=[[50,1000][50,1000]].

[0029] Reference Figure 2 and Figure 3 After the preparation work is completed, enter the measurement phase. The specific steps are as follows: At least one light beam is vertically incident on the surface of the thin film sample 6, and the reflected light beam is received by the reflected light probe 12.

[0030] The position of the film sample 6 is adjusted so that the film sample 6 is at a suitable test coordinate and angle.

[0031] Under appropriate test coordinates and angles, the position where the incident light beam 31 first hits the surface of the thin film sample 6 is the first position 61 , and the other position where the incident light beam 31 hits the surface of the thin film sample 6 after being reflected is the second position 62 .

[0032] When the light beam is incident vertically onto the surface of the thin film sample 6, the incident light beam 31 is reflected and refracted at the first position 61, thereby forming a first reflected light ray 32, and the refracted light ray is reflected at the interface between the thin film and silicon, and the reflected light ray is refracted at the interface between the thin film and air and leaves the thin film, thereby obtaining a second reflected light ray 33. The first reflected light ray 32 and the second reflected light ray 33 are incident on the second position 62 at the same time, and the first reflected light ray 32 and the second reflected light ray 33 are both reflected and refracted at the second position 62, so that the first reflected light ray 32 is reflected to form a third reflected light ray 34 and refracted to form a fourth reflected light ray 35, and the second reflected light ray 33 is reflected to form a fifth reflected light ray 36 and refracted to form a sixth reflected light ray 37, thereby facilitating the reflected light probe 12 to receive the first reflected light ray 32, the second reflected light ray 33, the third reflected light ray 34, the fourth reflected light ray 35, the fifth reflected light ray 36 and the sixth reflected light ray 37.

[0033] In summary, the fourth reflected light 35 , the fifth reflected light 36 and the sixth reflected light 37 meet the interference condition, so that the received spectral data can be parsed by constructing a suitable optical model to analyze the film thickness information of the thin film sample 6 .

[0034] It should be noted that when the incident light beam 31 is incident on the surface of the thin film sample 6, the area of ​​the light spot formed by the incident light beam 31 on the surface of the thin film sample 6 is larger than the area of ​​a single pyramid on the surface of the thin film sample 6, and the reflection directions of the corresponding reflected light on the four faces of the pyramid are different, so that the reflected light probe 12 can only receive the reflected light from one of the faces of the pyramid.

[0035] Set the incident light intensity at the first position 61 to I 0 , the effective incident light intensity is I 0_cal , I 0 The acquisition can be measured by a whiteboard or other standard sample through a light source and a spectrometer 1. It can be understood that the incident light hits the "pyramid" vertically. In the current algorithm, only the incident light on one side of the "pyramid" will participate in the calculation. The calculation formula for the effective incident light intensity is as follows: I 0_cal =0.25·I 0 .

[0036] It should be noted that the value calculated by the calculation formula for effective incident light intensity is an approximate value.

[0037] Reference Figure 3 and Figure 4 , according to the Fresnel formula and the transfer matrix method, the reflectivity of the light beam at the first position 61 is calculated, and the specific steps are as follows: For non-vertically incident s-waves and p-waves, according to the Fresnel formula, the reflection coefficients are: Among them, r s is the reflection coefficient of s wave, r p is the reflection coefficient of the p-wave, n1 is the refractive index of the incident medium, n2 is the refractive index of the transmission medium, θ1 is the incident angle, and θ2 is the refraction angle. And n1, n2, θ1 and θ2 satisfy the following relationship: According to the transmission matrix method, for each layer of the multilayer film, a characteristic matrix can be constructed according to the refractive index, thickness and incident angle of the layer. The specific construction formula is as follows: Among them, M i is the characteristic matrix of each layer of the multilayer film, cos(δ i )and These elements describe the phase changes and amplitude changes of light waves in a medium. and cos(δ i ) also describes phase and amplitude changes, but for different polarizations or directions of propagation. i is the phase thickness, which describes the phase difference accumulated when the light wave propagates in the medium. i is the thickness of the film, λ is the wavelength, n i is the refractive index of the medium, q i It is the wave vector component, which is related to the propagation direction and refractive index of the light wave in the medium, and is used to describe the reflection and transmission characteristics of the light wave at the medium interface.

[0038] After obtaining the characteristic matrix of each layer, the characteristic matrices are multiplied in sequence to obtain the transmission matrix of the entire multilayer film. The calculation formula is as follows: M total =M 1 ·M 2 ·…·M N Among them, M total is the transmission matrix of the entire multilayer film, M 1 , M 2 , ....., M N are the characteristic matrices of each layer in the multilayer film. total Calculate the reflectivity R at the first position 61 1 , the calculation formula is as follows: The above formula can be encapsulated as a function: f(param,x,bound). Among them, param is a parameter, which is a fixed value; x is the thickness of each layer, which is an unknown number; bound is the range of the thickness of each layer. And param contains the initial incident angle θ1, the refractive index list nlist , Extinction coefficient list k list , which can be expressed as: param = [θ1, n list ,k list ].

[0039] Reference Figure 3 and Figure 4 Next, the reflected light intensity at the first position 61 is calculated using the following formula: I R1 =R 1 I 0_cal Among them, I R1 is the reflected light intensity at the first position.

[0040] According to the intensity of the reflected light at the first position 61, the theoretical reflectivity at the second position 62 can be calculated, and the calculation formula is as follows: Among them, R 2_theory is the theoretical reflectivity, I R_exp is the reflected light intensity actually measured at the second position 62 .

[0041] The structures at the first position 61 and the second position 62 of the fitting film sample 6 are exactly the same, so the reflectivity coefficient and the transmittance coefficient at the second position 62 are the same as those at the first position 61. Therefore, when it is necessary to calculate the actual reflectivity at the second position 62, the function at the first position 61 can be directly called, and the calculation formula is as follows: in, is the reflectivity calculated at the second position 62 , and θ3 is the incident angle of the incident light at the second position 62 .

[0042] In this embodiment, the incident angle of the incident light at the first position 61 is θ1, and θ1=54.74°; the incident angle θ3 at the second position 62 is 15.78°. The specific derivation process is as follows: ∠θ3=90°-(180°-∠γ-∠β) ∠β=180°-2*∠θ1 ∠γ=90°-∠θ1 In summary, ∠θ3=180°-3*∠θ1.

[0043] Finally, by calculating the reflectivity at different wavelengths and substituting the calculated values ​​into the theoretical formula for calculation, the thickness value of the film sample 6 can be obtained. The specific theoretical formula is as follows: Among them, lamb start is the starting position of the calculated wavelength, lambend is the calculated wavelength end position, where the specific step size is related to the parameter settings of the spectrometer and the accuracy required for calculation. Through the calculation of the above formula, a function can be obtained to evaluate the similarity between the calculated reflectivity curve and the theoretical reflectivity curve. Then, all thickness values ​​within the thickness range are traversed for calculation. Each thickness value can get a corresponding Δr value. All Δr are combined to obtain an array Δr about all thickness values. list , take the minimum value, and the thickness value corresponding to the minimum value is the film thickness.

[0044] The embodiment of the present application also discloses a device for measuring the thickness of a thin film on a textured silicon substrate, which is used to implement the above-mentioned method for measuring the thickness of a thin film on a textured silicon substrate.

[0045] Reference Figure 2 A device for measuring the thickness of a thin film on a textured silicon substrate includes a spectrometer 1, a slave computer 2, a light source 3, a sample moving platform 4 and a box 5. The spectrometer 1 and the slave computer 2 are respectively arranged outside the box 5, and two spectrometers 1 are provided. The two spectrometers 1 are respectively electrically connected to the slave computer 2, so that the spectrometer 1 can transmit the spectrum signal to the slave computer 2, and the slave computer 2 is used to receive and send signals and perform data processing on the signals.

[0046] The spectrometer 1 is provided with an SMA905 interface for connecting an optical fiber. One spectrometer 1 is connected to an incident light probe 11 through an optical fiber for calibrating the incident light intensity information; the other spectrometer 1 is connected to a reflected light probe 12 through an optical fiber for receiving the light intensity information reflected from the second position 62. The incident light probe 11 and the reflected light probe 12 are respectively installed in the box 5.

[0047] The light source 3 and the sample moving stage 4 are respectively installed in the box 5, so as to eliminate the interference of external light and improve the measurement accuracy and stability. The incident light probe 11 is connected to the light source 3 through an optical fiber, and the optical fiber and the light source 3 also use an SMA905 interface, and the wavelength range is optional.

[0048] A film sample 6 is placed on the sample moving stage 4. In this embodiment, the sample moving stage 4 can drive the film sample 6 to move horizontally and rotate, so as to facilitate adjusting the angle and coordinate of the film sample 6, so as to facilitate measuring the film sample 6 at different angles and coordinates.

[0049] It should be noted that the specific structure of the sample moving stage 4 is a conventional technical means for those skilled in the art, and therefore will not be described in detail in the embodiments of the present application.

[0050] When the film sample 6 is placed on the sample moving stage 4, the angle between the incident light probe 11 and the horizontal plane of the film sample 6 is 90 degrees, and the spacing between the incident light probe 11 and the film sample 6 is 5-10 mm, so as to ensure that the light is incident vertically. At this time, the angle between the reflected light probe 12 and the horizontal plane of the film sample 6 is 50-52 degrees, and the spacing between the reflected light probe 12 and the film sample 6 is 5-10 mm, so that the reflected light probe 12 can receive the reflected light at a specific angle. In this embodiment, the angle between the reflected light probe 12 and the horizontal plane of the film sample 6 is 51 degrees.

[0051] The implementation principle of the device for measuring the thickness of a thin film on a textured silicon substrate in the embodiment of the present application is as follows: when the thickness of the thin film sample 6 needs to be measured, the light source 3 emits a light beam to the thin film sample 6 through the incident light probe 11, so that the light beam is vertically incident on the thin film sample 6. At this time, the reflected light probe 12 can receive the reflected light and transmit it to the spectrometer 1, so that the spectrometer 1 can convert the light signal into spectral data, and transmit the spectral data to the lower computer 2, so that the lower computer 2 can complete the thickness calculation according to the measurement data to measure the thickness of the thin film.

[0052] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for measuring the thickness of a thin film on a textured silicon substrate, characterized in that: The following steps are involved: At least one light beam is vertically incident on the surface of the thin film sample (6) and a reflected light beam is received; Adjusting the position of the film sample (6) so that the film sample (6) is at a suitable test coordinate and angle; Under appropriate test coordinates and angles, the position where the incident light beam (31) first incidents on the surface of the thin film sample (6) is a first position (61), and the other position where the incident light beam (31) incidents on the surface of the thin film sample (6) after reflection is a second position (62), and the incident light intensity and the effective incident light intensity at the first position (61) are determined; The reflectivity, transmittance and reflected light intensity of the light beam at the first position (61) are calculated, and based on this, the theoretical reflectivity and actual reflectivity at the second position (62) are calculated, and finally substituted into the theoretical formula to obtain the thickness of the film to be measured.

2. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 1, characterized in that: The incident light intensity at the first position (61) is set to I0, and the effective incident light intensity is set to I 0_cal , then the calculation formula for the effective incident light intensity is as follows: I 0_cal =0.25·I0.

3. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 2, characterized in that: The reflectivity of the light beam at the first position (61) is calculated, and the specific steps are as follows: According to the Fresnel formula and the transmission matrix method, the Fresnel formula is: And n1, n2, θ1 and θ2 satisfy the following relationship: The transfer matrix method is: M total =M1·M2·…·M N Among them, r s is the reflection coefficient of s wave, r p is the reflection coefficient of the p-wave, n1 is the refractive index of the incident medium, n2 is the refractive index of the transmission medium, θ1 is the incident angle, θ2 is the refraction angle, M i is the characteristic matrix of each layer of the multilayer film, cos(δ i )and These elements describe the phase and amplitude changes of light waves in a medium; and cos(δ i ) also describes the phase and amplitude changes, but corresponds to different polarizations or propagation directions; δ i is the phase thickness, which describes the phase difference accumulated when the light wave propagates in the medium; d i is the thickness of the film, λ is the wavelength, q i is the wave vector component, M total is the transmission matrix of the entire multilayer film, and R1 is the reflectivity at the first position (61).

4. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 3, characterized in that: The calculation formula for calculating the intensity of the reflected light at the first position (61) is as follows: I R1 =R1I 0_cal Among them, I R1 is the reflected light intensity at the first position (61).

5. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 4, characterized in that: Assuming that the Fresnel formula and the transfer matrix method can be encapsulated as a function: f(param, x, bound), the calculation formulas for the theoretical reflectivity and the actual reflectivity at the second position (62) are as follows: R 2_cal =f(param,x,bound),param=[θ3,n list ,k list ] Among them, param is the parameter, x is the thickness value of each layer, bound is the range of the thickness value of each layer, R 2_theory is the theoretical reflectivity of the second position (62), I R_exp is the reflected light intensity actually measured at the second position (62), R 2_cal is the reflectivity calculated at the second position (62), and θ3 is the incident angle of the incident light at the second position (62).

6. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 5, characterized in that: The theoretical formula is: Among them, lamb start is the starting position of the calculated wavelength, lamb end is the calculated wavelength end position, where the specific step size is related to the parameter settings of the spectrometer and the accuracy required for calculation. Through the calculation of the above formula, a function can be obtained to evaluate the similarity between the calculated reflectivity curve and the theoretical reflectivity curve. Then, all thickness values ​​within the thickness range are traversed for calculation. Each thickness value can get a corresponding Δr value. All Δr are combined to obtain an array Δr about all thickness values. list , take the minimum value, and the thickness value corresponding to the minimum value is the film thickness.

7. The method for measuring the thickness of a thin film on a textured silicon substrate according to claim 5, characterized in that: θ3=180°-3·θ1.

8. A device for measuring the thickness of a thin film on a textured silicon substrate, used in the method for measuring the thickness of a thin film on a textured silicon substrate as claimed in any one of claims 1 to 7, characterized in that: include: Light source (3); Two spectrometers (1) are provided, one of the spectrometers (1) is connected to an incident light probe (11) via an optical fiber, the incident light probe (11) is connected to the light source (3) via an optical fiber, and the other spectrometer (1) is connected to a reflected light probe (12) via an optical fiber, and the light source (3) can emit a light beam through the incident light probe (11); A sample moving platform (4), on which a thin film sample (6) is placed, and the sample moving platform (4) is capable of adjusting the angle and position of the thin film sample (6); The lower computer (2) is connected to the two spectrometers (1) respectively.

9. The device for measuring the thickness of a thin film on a textured silicon substrate according to claim 8, characterized in that: It comprises a box (5), wherein the light source (3), the incident light probe (11), the reflected light probe (12) and the sample moving platform (4) are respectively arranged in the box (5).

10. The device for measuring the thickness of a thin film on a textured silicon substrate according to claim 8, characterized in that: The angle between the incident light probe (11) and the horizontal plane of the thin film sample (6) is 90 degrees, and the angle between the reflected light probe (12) and the horizontal plane of the thin film sample (6) is 50-52 degrees.

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