A method and system for measuring film thickness and refractive index based on white light interference and white light atomic force scanning technology

Abstract

The application discloses a film thickness and refractive index measurement method based on white light interference and white light atomic force scanning technology, and comprises the following steps: S1, acquiring the top surface and bottom surface topography distribution of a film medium substrate under a white light interference measurement mode; S2, acquiring the top surface and top surface topography distribution of the film medium substrate under a white light atomic force scanning mode; and S3, calibrating and correcting the topography distribution obtained under the white light interference measurement mode based on the topography distribution obtained under the white light atomic force scanning mode, and obtaining the film thickness and refractive index. The film thickness and refractive index measurement method based on white light interference and white light atomic force scanning technology combines the scanning white light interference measurement principle and the equivalent optical path principle, calibrates and corrects the scanning white light interference data, and obtains the film material refractive index N.

Description

Technical Field

[0001] This invention belongs to the field of thin film morphology detection technology, and more specifically, relates to a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology. Background Technology

[0002] Thin film technology is widely used in the semiconductor and biopharmaceutical industries and is currently a research hotspot in materials science. The main purpose of thin film measurement is to obtain parameters such as film thickness, refractive index, reflectivity, and extinction coefficient, as well as the surface morphology distribution of the film. Accurate measurement of these parameters of thin films is of great significance.

[0003] There are many methods for measuring thin film thickness. Currently, one of the main methods for measuring thin film morphology is vertical scanning white light interferometry (PSI). By separating the distance between the interference peaks on the upper and lower surfaces of the thin film in the vertical scanning signal of white light and combining this with the prior material refractive index, the film thickness and surface height can be obtained. However, the thinnest thickness that PSI can measure is limited by the coherence length of the white light. When the film thickness is less than the coherence length, the interference peaks on the upper and lower surfaces overlap, leading to inaccurate measurement results. Especially for submicron-level thin film measurements, the measurement accuracy is particularly important. Summary of the Invention

[0004] To address at least one deficiency or improvement requirement of the existing technology, the present invention provides a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology, aiming to solve the problem of measuring thin film thickness and refractive index, especially at the submicron level.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology is provided, comprising:

[0006] S1: Obtain the morphological distribution of the upper and lower surfaces of the thin film substrate under white light interferometry mode;

[0007] S2: Obtain the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface under white light atomic force scanning mode;

[0008] S3: Based on the morphology distribution obtained in the white light atomic force scanning mode, the morphology distribution obtained in the white light interferometry mode is calibrated and corrected to obtain the film thickness and refractive index.

[0009] Preferably, step S1 includes:

[0010] In white light interferometry mode, vertical scanning is performed on the upper surface and lower surface of the thin film substrate to obtain the interference image of each pixel.

[0011] The morphology distribution of the upper and lower surfaces of the thin film substrate is obtained by using the equivalent optical path algorithm to restore the morphology of the interference image.

[0012] Preferably, the equivalent optical path algorithm includes:

[0013]

[0014]

[0015]

[0016] In the formula: I1, I2, I3, I4, and I5 represent the light intensities of five equally spaced interferometric images; step is the sampling step size; V 2 The modulation index is represented by N and s, which represent the maximum number of frames and phase of the modulation index, respectively, and h is the height of the film to be measured.

[0017] Preferably, step S2 includes:

[0018] In white light atomic force scanning mode, the positional relationship between the vertical displacement of the white light atomic force scanning probe and the corresponding interference fringe displacement is determined;

[0019] The horizontal displacement and corresponding interference fringe shift of the white-light atomic force probe at each position in the horizontal direction are obtained;

[0020] The height information for each location is calculated based on the calibration results.

[0021] Preferably, the positional relationship between the vertical displacement of the calibrated white light atomic force scanning probe and the corresponding interference fringe displacement includes:

[0022] Within the calibration range, obtain the vertical displacement Z of the white light atomic force scanning probe in the vertical direction and the corresponding interference fringe shift x;

[0023] A fitting model was established between the vertical displacement of the white light atomic force scanning probe and the corresponding shift of the interference fringes, and the fitting coefficients were calculated. The fitting model is as follows:

[0024] Z = a·x 3 +b·x 2 +c·x+d

[0025] In the formula, Z is the vertical displacement of the white light atomic force scanning probe; x is the movement of the interference fringes; and a, b, c, and d are the fitting coefficients.

[0026] Preferably, the calibration and correction of the morphology distribution data obtained in the white light interferometry mode in step S3 includes:

[0027] The morphology distribution measured in the white light interferometry mode and the white light atomic force scanning mode are respectively divided into characteristic regions. The morphology distribution data measured in the white light interferometry mode is corrected using the morphology distribution data measured in the white light atomic force scanning mode.

[0028] Preferably, the formula for calculating the film thickness in step S3 is:

[0029] Δ=|H0-H1|;

[0030] In the formula, Δ is the film thickness; H1 is the height of the upper surface of the film measured in white light atomic force scanning mode; and H0 is the height of the upper surface of the film dielectric substrate measured in white light atomic force scanning mode.

[0031] The formula for calculating the refractive index of the thin film is:

[0032]

[0033] In the formula, n is the refractive index of the thin film; H1 is the height of the upper surface of the thin film measured in white light atomic force scanning mode; H0 is the height of the surface of the thin film dielectric substrate measured in white light atomic force scanning mode; h0 is the height of the upper surface of the thin film dielectric substrate measured in white light interferometry mode; and h2 is the equal optical path modulation height of the lower surface of the thin film measured in white light interferometry mode.

[0034] Preferably, the method further includes preprocessing the interference fringes obtained by the white light atomic force scanning probe to eliminate distortion of the interference signal;

[0035] The phase distribution of the preprocessed interference fringes was solved using the Hilbert transform.

[0036] Preferably, the film is a transparent or semi-transparent film, and the film is distributed on a smooth dielectric substrate.

[0037] According to another aspect of the present invention, a thin film thickness and refractive index measurement system based on white light interferometry and white light atomic force scanning technology is also provided, comprising:

[0038] The white light interferometry module is used to acquire the morphological distribution of the upper and lower surfaces of the thin film dielectric substrate under white light interferometry mode.

[0039] The white light atomic force scanning module is used to acquire the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface in white light atomic force scanning mode.

[0040] The calculation module is used to calibrate and correct the morphology distribution obtained in the white light interferometry mode based on the morphology distribution obtained in the white light atomic force scanning mode, and to obtain the film thickness and refractive index.

[0041] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0042] (1) The present invention provides a method for measuring the thickness and refractive index of thin films based on white light interferometry and white light atomic force scanning technology. The method uses two measurement modes, white light interferometry and atomic force probe scanning, to measure the thin film. By fusing the morphology distribution data under the two measurement modes, the morphology distribution data obtained by the white light atomic force scanning measurement mode is used to correct the morphology distribution data obtained by the white light interferometry measurement mode. This overcomes the errors caused by optical path modulation and inability to distinguish interference peaks in the process of measuring the morphology distribution of thin films, thereby improving the accuracy of the measurement of the thickness and refractive index of thin films.

[0043] (2) The present invention provides a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology. The morphology recovery accuracy of white light interferometry can reach the sub-nanometer level, and the accuracy of white light atomic force scanning can reach 1 nm. Therefore, the error of white light interferometry and atomic force scanning in measuring the height of the thin film substrate and the thin film surface, i.e., the thin film thickness, does not exceed [the specified value]. It has extremely high precision and can be used to measure submicron-level film thickness and refractive index.

[0044] (3) The present invention provides a method for measuring the thickness and refractive index of thin films based on white light interference and white light atomic force scanning technology. In the atomic force probe scanning measurement mode, the obtained interference fringes are preprocessed to eliminate the distortion of the interference signal, which further improves the accuracy of the measurement. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of a thin film thickness and refractive index measurement method based on white light interferometry and white light atomic force scanning technology provided in an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of a thin film thickness and refractive index measurement method based on white light interferometry and white light atomic force scanning technology provided in an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the principle of the white light interferometry and white light atomic force scanning measurement system provided in the embodiments of the present invention;

[0048] Figure 4 This is a flowchart of a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology provided in an embodiment of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0050] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] This invention proposes a method for detecting thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology. Existing submicron-level thin film thickness measurement methods suffer from significant errors. Firstly, as described in the background section, when the thin film thickness is less than a certain range, it is smaller than the white light interference length. Directly measuring the film thickness using a white light interferometer results in interference peaks with lower reflectivity on the upper surface of the film being completely masked by interference fringes reflected from the lower surface, leading to aliasing between the signal interference peaks on the upper and lower surfaces and inaccurate measurement results. Secondly, when measuring transparent or translucent materials, the surface morphology measured by the white light interferometry method is affected by optical path refraction modulation in the transparent or translucent regions, resulting in an equivalent optical path modulation deviation, thus making it impossible to directly obtain the true thickness of the thin film. Figure 1 and Figure 2 This is a schematic diagram of the thin film thickness and refractive index measurement method of the present invention, as shown below. Figure 1 and 2 As shown, the thin film covers the surface of the dielectric substrate. The atomic force scanning mode measures the correct morphology distribution of the thin film, with the height of the lower surface of the thin film being higher than the height of the dielectric substrate surface. However, the morphology distribution measured by the white light interferometry mode, due to the influence of the equivalent optical path modulation mentioned above, shows that the height of the thin film is actually lower than the height of the dielectric substrate, and the measurement result is obviously incorrect.

[0055] Based on the above problems, the core concept of this invention lies in combining white light interferometry and white light atomic force scanning measurement. The white light interferometry mode is used to obtain the morphology distribution data of the thin film substrate and the lower surface of the thin film, and the white light atomic force scanning measurement mode is used to obtain the morphology distribution data of the thin film substrate and the upper surface of the thin film. The morphology distribution data from the two measurement modes are fused, and the morphology distribution data obtained from the white light atomic force scanning measurement mode is used to correct the morphology distribution data obtained from the white light interferometry mode, thereby eliminating the error in the process of measuring the morphology distribution of the thin film and obtaining the film thickness and refractive index.

[0056] This invention provides a method for detecting thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology. Figure 3This is a schematic diagram of the white light interferometry and white light atomic force scanning measurement system used in this method. The white light interferometry and white light atomic force scanning measurement system combines two measurement systems: white light interferometry and white light atomic force scanning measurement. The switching between the two measurement modes is achieved through a pose adjustment mechanism.

[0057] like Figure 3 The white light interferometry and white light atomic force scanning measurement system shown includes a stage for placing a sample, which is placed on a horizontal XY nano-drive platform 6. Above the stage, from bottom to top along the optical path, are arranged an atomic force probe 10, a cantilever 11, a Mirau interferometer objective 5, a vertical piezoelectric ceramic positioner (not shown in the figure), a beam splitter 7, a reflector 2, a second lens 8, a monochrome CMOS camera 9, and a laser interferometry vertical metrology module 1. On the incident light path of the beam splitter 7, from the inside out, are a first lens 4 and a white light broadband light source 3. The signal input / output terminals of the CMOS camera 9, the horizontal XY nano-drive platform 6, and the vertical piezoelectric ceramic positioner are respectively connected to a computer. The atomic force scanning probe 10 is mounted on the cantilever 11, and the vertical piezoelectric ceramic positioner controls the fine adjustment of the vertical displacement of the atomic force scanning probe 10. In white light measurement mode, the atomic force scanning probe 10 is retracted to the side and does not appear in the field of view of the CMOS camera 9; after the measurement system switches to white light atomic force scanning measurement mode, the atomic force scanning probe 10 rotates into the field of view of the CMOS camera 9 under the control of the mode switching mechanism.

[0058] Figure 4 This invention relates to a method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology, such as... Figure 4 The method for measuring thin film thickness and refractive index using white light interferometry and white light atomic force scanning technology, as shown, includes:

[0059] S1: Obtain the morphological distribution of the upper and lower surfaces of the thin film substrate under white light interferometry mode;

[0060] S2: Obtain the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface under white light atomic force scanning mode;

[0061] S3: Based on the morphology distribution obtained in the white light atomic force scanning mode, the morphology distribution obtained in the white light interferometry mode is calibrated and corrected to obtain the film thickness and refractive index.

[0062] It should be noted that, in this art, morphology distribution refers to the height distribution of the object being measured relative to the measurement reference, where height specifically refers to the distance between the object being measured and the measurement reference. The surface of the thin-film dielectric substrate described in this invention refers to the upper surface of the thin-film dielectric substrate. This invention is applicable to transparent or semi-transparent thin films, with the thin film being measured distributed on a flat thin-film dielectric substrate.

[0063] Specifically, step S1 includes:

[0064] (1.1) Turn on the white light broadband light source, place the thin film sample to be tested on the stage, and adjust the measurement system to the vertical scanning white light interference mode;

[0065] (1.2) Vertical scanning white light interferometry is performed on the upper and lower surfaces of the thin film dielectric substrate to obtain the interference image of each pixel; including:

[0066] Adjust the PZT until white light interference fringes appear, set the vertical scanning range of the PZT so that the vertical scan can encompass all positions where interference fringes exist, drive the PZT to achieve vertical scanning, and save each frame of interference image during the scanning process; preferably, vertical scanning is performed with a scanning step size less than one-quarter of the minimum wavelength of the light source spectrum.

[0067] (1.3) The morphology of the interference image is restored according to the equivalent optical path algorithm to obtain the morphology distribution of the interference image on the surface of the thin film substrate and the lower surface of the thin film:

[0068] In one specific embodiment, the Stoilov constant-step phase-shift algorithm is used to solve the equivalent optical path algorithm, and the topography of the interferogram obtained by vertical scanning is restored, including:

[0069]

[0070] In the formula: I1, I2, I3, I4, and I5 are the light intensities of five equally spaced interferometric images, respectively, and step is the sampling step size. V 2 The modulation index is represented by N and φ0, which represent the maximum number of frames and phase of the modulation index, respectively. h is the height of the surface under test (in the heterogeneous material region, this height is affected by the refractive index optical path modulation).

[0071] Step S2 includes:

[0072] During the measurement process, after completing the white light interferometric vertical scan measurement, the atomic force probe assembly is moved in, and the measurement system is switched to the white light interferometric atomic force scan measurement mode.

[0073] Acquire the horizontal displacement and corresponding interference fringe shift of a white-light interferometric atomic force probe at each position on the thin film and dielectric substrate in the horizontal direction;

[0074] Based on a fitting model of the vertical displacement of a white-light interferometric atomic force probe and the corresponding shift of the interference fringes, the height information at each position is obtained. Specifically,

[0075] (2.1) Adjust the measurement system to white light interferometry atomic force scanning mode;

[0076] (2.2) The atomic force probe tip is brought into contact with the sample surface by the automatic contact function of the white light interference atomic force probe;

[0077] (2.3) Drive the PZT within the calibration range and record the vertical displacement of the probe under the drive of the PZT using the laser interferometric vertical metrology module. Then, calibrate the relationship between the movement of the zero-order fringe of white light interference on the atomic force cantilever and the vertical displacement of the atomic force probe.

[0078] (2.4) Drive the horizontal XY nano-drive platform so that the atomic force probe scans the sample under test in the horizontal direction and saves each frame of the image and the corresponding horizontal displacement during the scanning process.

[0079] (2.5) Calculate the amount of white light interference zero-order fringe movement on the atomic force probe cantilever during the scanning process, and determine the height information of each position according to the calibration results in (2.3) to realize the morphology restoration of the thin film substrate and the upper surface of the thin film.

[0080] The specific fitting model for the vertical displacement of the white light interferometer atomic force probe and the corresponding shift of the interference fringes is as follows:

[0081] Z = a·x 3 +b·x 2 +c·x+d

[0082] In the formula: a, b, c, d are the coefficients to be fitted;

[0083]

[0084] The model parameters a, b, c, d are calculated by least-squares cubic curve fitting.

[0085] During the measurement process, the atomic force probe cantilever is in a bent state to varying degrees, which leads to uneven light intensity distribution in the white light interference image acquired by the CCD. This causes distortion in the extracted interference fringe signal, mainly manifested as unclear fringe order, fringe tilt, and signal asymmetry.

[0086] Therefore, it is necessary to preprocess the interference fringes obtained by white light interferometry atomic force probe scanning to eliminate the distortion of the interference signal; specifically including:

[0087] Wavelet transform is used to preprocess the extracted interference signal to eliminate its distortion; Hilbert transform is used to solve for the phase distribution of the preprocessed interference signal. By solving for the zero-phase position, the position of the zero-order fringe on the probe microcantilever can be accurately obtained.

[0088] Gradient decay preprocessing:

[0089] In the formula: x i The low-frequency component is obtained after wavelet decomposition; A is the amplification factor, which is determined based on the degree of signal skewness, i.e., the degree of deformation of the atomic force probe; the logarithm of the amplified low-frequency component is denoted as O(Ax). i ); α is O(Ax) i The average value of ) is 0.85 to 1.0, depending on the contrast of the signal.

[0090] The preprocessed interference signal conforms to the intensity distribution of a standard white light interference signal, and its expression is:

[0091] I(x) = p(x) + q(x)cos[φ(x)]

[0092] In the formula: I(x) represents the fringe intensity; x represents the fringe coordinate; p(x) represents the background light intensity; q(x) represents the modulation intensity function of the fringe; φ(x) represents the phase term related to the measured information.

[0093] The phase decomposition of the Hilbert transform is achieved by performing two consecutive Hilbert transforms on the interference signal and then performing an arctangent operation on the results of the two Hilbert transforms. The resulting phase decomposition is as follows:

[0094]

[0095] By performing row least squares fitting on the discrete phase distribution and then solving for the abscissa of the zero phase point of the phase segment with the largest gray value, the position x0 of the zero-order fringe on the probe microcantilever can be accurately obtained.

[0096] Substituting into the probe vertical displacement fitting model in (2.3), we get:

[0097] Z0 = a·x0 3 +b·x0 2 +c·x0+d

[0098] H = Z0

[0099] In the formula: Z0 is the vertical displacement of the probe, and H is the height of the sample surface.

[0100] Obtaining the film thickness in step S3 includes:

[0101] The morphology distributions measured in the white light interferometry mode and the white light atomic force scanning mode are respectively divided into characteristic regions. The morphology distribution data measured in the white light atomic force scanning mode are used to correct the morphology distribution data measured in the white light interferometry mode. The film thickness calculation formula is:

[0102] Δ=|H0-H1|;

[0103] In the formula, H1 is the height of the upper surface of the thin film measured in white light interferometry atomic force probe mode; H0 is the height of the thin film dielectric substrate.

[0104] The formula for calculating the refractive index of a thin film is:

[0105]

[0106] In the formula, H1 is the height of the upper surface of the thin film measured in white light interferometry atomic force probe mode; H0 is the height of the thin film dielectric substrate; h0 is the height of the thin film dielectric substrate measured in white light interferometry mode; The isooptic path modulation height of the lower surface of the thin film is measured in white light interferometry mode.

[0107] Because vertical scanning white light interferometry can achieve sub-nanometer accuracy in morphology recovery, meaning the vertical accuracy in the measured thin film sample's dielectric substrate region is higher than 1 nm, and white light atomic force scanning (AFS) can achieve an accuracy of 1 nm, the error in measuring the height (i.e., film thickness) between the thin film dielectric substrate and the film surface using white light interferometry AFS does not exceed [a certain value]. The accuracy is extremely high.

[0108] This invention also provides a thin film thickness and refractive index measurement system based on white light interferometry and white light atomic force scanning technology, comprising:

[0109] The white light interferometry module is used to acquire the morphological distribution of the upper and lower surfaces of the thin film dielectric substrate under white light interferometry mode.

[0110] The white light atomic force scanning module is used to acquire the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface in white light atomic force scanning mode.

[0111] The calculation module is used to calibrate and correct the morphology distribution obtained in the white light interferometry mode based on the morphology distribution obtained in the white light atomic force scanning mode, and to obtain the film thickness and refractive index.

[0112] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the thickness and refractive index of thin films based on white light interferometry and white light atomic force scanning technology, characterized in that, include: S1: Obtain the morphological distribution of the upper and lower surfaces of the thin film substrate under white light interferometry mode; S2: Obtain the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface under white light atomic force scanning mode; S3: Based on the morphology distribution obtained in the white light atomic force scanning mode, the morphology distribution obtained in the white light interferometry mode is calibrated and corrected to obtain the film thickness and refractive index. Specifically, this includes: dividing the morphology distribution measured in the white light interferometry mode and the white light atomic force scanning mode into characteristic regions, and correcting the morphology distribution measured in the white light interferometry mode using the morphology distribution measured in the white light atomic force scanning mode. The formula for calculating film thickness is: ； In the formula, For film thickness, The height of the thin film surface as measured in white light atomic force scanning mode. The height of the upper surface of the thin film dielectric substrate as measured in white light atomic force scanning mode; The formula for calculating the refractive index of a thin film is: ； In the formula, For the refractive index of the thin film, The height of the upper surface of the thin-film dielectric substrate measured in white light interferometry mode. The isooptic path modulation height of the lower surface of the thin film is measured in white light interferometry mode.

2. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 1, characterized in that, Step S1 includes: In white light interferometry mode, vertical scanning is performed on the upper surface and lower surface of the thin film substrate to obtain the interference image of each pixel. The morphology distribution of the upper and lower surfaces of the thin film substrate is obtained by using the equivalent optical path algorithm to restore the morphology of the interference image.

3. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 2, characterized in that, The equivalent optical path algorithm includes: In the formula: The light intensities of five equally spaced interference images are respectively sampled. The sampling step size; Indicates adjustment system, These represent the maximum number of frames and the phase, respectively. The height of the film to be measured is denoted as .

4. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 1, characterized in that, Step S2 includes: In white light atomic force scanning mode, the positional relationship between the vertical displacement of the white light atomic force scanning probe and the corresponding interference fringe displacement is determined; The horizontal displacement and corresponding interference fringe shift of the white-light atomic force probe at each position in the horizontal direction are obtained; The height information for each location is calculated based on the calibration results.

5. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 4, characterized in that, The positional relationship between the vertical displacement of the calibrated white light atomic force scanning probe and the corresponding interference fringe displacement includes: Within the calibration range, obtain the vertical displacement Z of the white-light atomic force scanning probe in the vertical direction and the corresponding shift of the interference fringes. ; A fitting model was established between the vertical displacement of the white light atomic force scanning probe and the corresponding shift of the interference fringes, and the fitting coefficients were calculated. The fitting model is as follows: In the formula, This represents the vertical displacement of the white light atomic force scanning probe. This represents the amount of shift in the interference fringes; The fitting coefficients are denoted as .

6. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 1, characterized in that, It also includes preprocessing the interference fringes obtained by the white light atomic force scanning probe to eliminate the distortion of the interference signal; The phase distribution of the preprocessed interference fringes was solved using the Hilbert transform.

7. The method for measuring thin film thickness and refractive index based on white light interferometry and white light atomic force scanning technology as described in claim 1, characterized in that, The film is a transparent or semi-transparent film, and the film is distributed on a smooth dielectric substrate.

8. A thin film thickness and refractive index measurement system based on white light interferometry and white light atomic force scanning technology, characterized in that, include: The white light interferometry module is used to acquire the morphological distribution of the upper and lower surfaces of the thin film dielectric substrate under white light interferometry mode. The white light atomic force scanning module is used to acquire the upper surface of the thin film dielectric substrate and the morphology distribution of the thin film upper surface in white light atomic force scanning mode. The calculation module is used to calibrate and correct the morphology distribution obtained in the white light interferometry mode based on the morphology distribution obtained in the white light atomic force scanning mode, and to obtain the film thickness and refractive index. Specifically, it includes: dividing the morphology distribution measured in the white light interferometry mode and the white light atomic force scanning mode into characteristic regions, and correcting the morphology distribution measured in the white light interferometry mode using the morphology distribution measured in the white light atomic force scanning mode. The film thickness calculation formula is as follows: ； In the formula, For film thickness, The height of the thin film surface as measured in white light atomic force scanning mode. The height of the upper surface of the thin film dielectric substrate as measured in white light atomic force scanning mode; The formula for calculating the refractive index of a thin film is: ； In the formula, For the refractive index of the thin film, The height of the upper surface of the thin-film dielectric substrate measured in white light interferometry mode. The isooptic path modulation height of the lower surface of the thin film is measured in white light interferometry mode.

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