A film thickness measuring device and method

Abstract

The application discloses a thin film thickness measuring device and method, and relates to the technical field of optical measurement. The thin film thickness measuring device provided by the application is designed with an objective lens probe sharing the light paths of incident light and reflected light, can approximately focus the incident light of a light source optical fiber on a to-be-measured thin film, and controls the incident angle through the objective lens probe in a small range, which is beneficial to simplifying a reflection model and improving measuring efficiency. Moreover, the application can reshape the reflected light into a ring-shaped distributed light image through the objective lens probe, which is well matched with the merging end of a Y-shaped multi-core optical fiber, so that most of the reflected light enters the detection optical fiber, the reflected light entering the light source optical fiber can be effectively avoided, and then the light energy utilization rate is greatly improved, and the measuring precision is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and in particular to a thin film thickness measurement device and method. Background Technology

[0002] Thin films are widely used in the manufacturing and processing of key components such as solar cells and semiconductor chips, and can be used for substrate protection, catalytic reactions, and photoelectric conversion. Thin film thickness measurement is crucial for manufacturing process control and quality inspection. Besides more direct methods like step-by-step or cross-sectional measurement, indirect physical property measurement methods are increasingly employed for thin film thickness measurement. These methods deduce the film thickness by detecting certain physical properties of the film, including weighing methods, electrical methods, and optical methods. Among these, optical methods, with their advantages of non-contact operation, high resolution, and high efficiency, have received particular attention and research.

[0003] Optical methods typically infer the thickness of the thin film by detecting its reflection or transmission spectra, such as elliptic polarization, spectrophotometry, integrating sphere method, and fiber optic spectrophotometry. Elliptic polarization offers high sensitivity and a wide range of measurable media, but its equipment is complex, costly, and poorly integrateable. Spectrophotometry allows for the combined measurement of reflectance and absorbance, but suffers from dispersion effects, large spot size, complex structure, and high cost. Integrating sphere method is simple in principle and offers diverse illumination modes, but it can cause contact damage, and ordinary integrating spheres are large and inconvenient to integrate.

[0004] In comparison, fiber optic spectral splitting offers greater flexibility. It obtains the spectral reflectance of the film under test by comparing its reflection spectra with those of a standard mirror, and then calculates the film thickness by comparing this reflectance with the theoretical spectral reflectance. The light source, the film under test, and the detector are connected via optical fibers (fiber couplers or Y-type multi-core fibers), allowing for high equipment integration without being limited by fixed spatial layouts. However, fiber optic spectral splitting also has limitations. For example, using fiber couplers results in significant light intensity loss at the coupling point. While Y-type multi-core fibers offer lower fiber loss, most of the divergent beam exiting the fiber end face cannot return to the fiber without a focusing objective, leading to low light energy utilization. Furthermore, the numerical aperture of the fiber allows for a wide range of reflected beam angles, resulting in a broader range of incident angles and a more complex reflection model, which inevitably reduces the efficiency of film thickness calculation. When Y-type multi-core optical fiber and focusing lens are used in combination, according to the principle of optical conjugation, the light beam emitted from the end face of the light source fiber is projected onto the thin film through the focusing lens. The light beam reflected from the thin film will still be mainly focused on the end face of the light source fiber, resulting in the end face of the probe fiber only receiving a small portion of the reflected light, which will also cause the problem of low light energy utilization.

[0005] Furthermore, current methods for calculating film thickness also have shortcomings. Common reflectance film thickness gauges generally use a standard of known spectral reflectance for comparative measurement. However, since spectral reflectance is not only related to inherent optical properties but also to the incident angle during the measurement process, and the standard known spectral reflectance is often obtained from literature or other instruments such as spectrophotometers, the incident angle when the reflectance film thickness gauge measures the film sample often differs from the incident angle when obtaining the standard known spectral reflectance. This leads to traceability errors when calculating the absolute spectral reflectance of the film sample using the known spectral reflectance, resulting in errors in the final film thickness. Summary of the Invention

[0006] The purpose of this invention is to provide a thin film thickness measuring device and method that can improve both the measurement efficiency and accuracy of thin film thickness.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A thin film thickness measuring device includes: a light source, a Y-type multi-core optical fiber, an objective lens probe, a spectrometer, and a processor;

[0009] The Y-type multi-core optical fiber includes a light source fiber and multiple probe fibers;

[0010] One end of the light source optical fiber is connected to the light source; one end of each of the multiple detection optical fibers is connected to the spectrometer; the other end of the light source optical fiber and the other ends of the multiple detection optical fibers form a confluence and are connected to the objective lens probe; the spectrometer is electrically connected to the processor.

[0011] Optionally, one end of the multiple detection optical fibers is arranged in a straight line and connected to the spectrometer; the other ends of the multiple detection optical fibers are arranged circumferentially with the other end of the light source optical fiber as the center.

[0012] Optionally, the objective lens probe includes: a first spherical lens, a first conical lens, a second spherical lens, a second conical lens, a fixing block, a cavity, and an optical fiber interface;

[0013] The fiber optic interface, the first spherical lens, the first conical lens, the second spherical lens, and the second conical lens are arranged along the same optical axis, and the first spherical lens, the first conical lens, the second spherical lens, and the second conical lens are all fixed in the cavity by the fixing block.

[0014] Optionally, the objective lens probe includes: a first spherical lens, a first conical lens, a second spherical lens, a fixing block, a cavity, and an optical fiber interface;

[0015] The fiber optic interface, the first spherical lens, the first conical lens, and the second spherical lens are arranged along the same optical axis, and the first spherical lens, the first conical lens, and the second spherical lens are all fixed in the cavity by the fixing block.

[0016] Optionally, the spectrometer is provided with a slit structure; the slit structure is parallel to the linearly arranged detection optical fibers to receive light from the detection optical fibers.

[0017] Optionally, the processor is a system or device with an embedded smart processing chip.

[0018] Optionally, the radius of the detection optical fiber is not less than the radius of the light source optical fiber.

[0019] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0020] The thin film thickness measurement device provided by this invention features an objective lens probe that shares the same optical path for both incident and reflected light. This allows for the approximate focusing of the incident light from the light source fiber onto the film under test. Furthermore, the objective lens probe controls the incident angle within a relatively small range, simplifying the reflection model and improving measurement efficiency. Moreover, by employing an objective lens probe, this invention can shape the reflected light into a ring-shaped backlight image, which matches well with the confluence end of the Y-shaped multi-core fiber. This ensures that most of the reflected light enters the probe fiber, effectively preventing reflected light from entering the light source fiber. Consequently, the light energy utilization rate is greatly improved, significantly enhancing measurement accuracy.

[0021] The present invention also provides a method for measuring film thickness, applicable to the film thickness measuring device provided above; the film thickness measuring method includes:

[0022] The noise spectrum, the metal mirror reflection spectrum, and the thin film under test were obtained respectively.

[0023] The relative spectral reflectivity of the thin film under test is determined based on the noise spectrum, the reflection spectrum of the metal mirror, and the reflection spectrum of the thin film under test.

[0024] The theoretical spectral reflectivity of the metal mirror is determined based on the incident angle of the objective lens probe, the optical constants of the metal and the coating of the metal mirror, and the preset coating thickness d1 of the metal mirror.

[0025] The absolute spectral reflectance of the thin film under test is determined based on the theoretical spectral reflectance of the metal mirror and the relative spectral reflectance of the thin film under test.

[0026] Based on the optical constants of the substrate and coating of the thin film under test, and the preset film thickness d2, the theoretical spectral reflectance of the thin film under test is determined.

[0027] Determine the goodness of fit between the theoretical spectral reflectance and the absolute spectral reflectance of the thin film under test;

[0028] When the fitting degree reaches the preset requirement, the preset film thickness d2 is determined as the thickness of the film to be measured; specifically, the preset metal mirror coating thickness d1 and the preset film thickness d2 are used as parameters to perform the fitting degree optimization inversion solution to obtain the preset film thickness d2 when the fitting degree is optimal; the preset film thickness d2 when the fitting degree is optimal is the thickness of the film to be measured.

[0029] Optionally, the noise spectrum, the metal mirror reflection spectrum, and the thin film reflection spectrum are acquired separately, specifically including:

[0030] Without turning on the light source or placing the film to be tested, multiple sets of background noise signals are acquired within a set time period, and the multiple sets of background noise signals are averaged to obtain the noise spectrum;

[0031] The metal reflector is placed at a preset distance from the objective lens probe, and the light source is turned on to obtain the first light intensity distribution signal; the first light intensity distribution signal is the light intensity distribution signal of the metal reflector at different wavelengths within a set time after the light source is turned on.

[0032] The reflection spectrum of the metal mirror is obtained by averaging the first light intensity distribution signal.

[0033] Replace the metal reflector with the film to be tested, and place the film to be tested at a preset distance from the objective lens probe. Turn on the light source to obtain a second light intensity distribution signal. The second light intensity distribution signal is the light intensity distribution signal of the film to be tested at different wavelengths within a set time after the light source is turned on.

[0034] The reflection spectrum of the thin film under test is obtained by averaging the second light intensity distribution signal.

[0035] Since the technical effects achieved by the thin film thickness measurement method provided by this invention are the same as those achieved by the device provided by this invention, they will not be described again here. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A schematic diagram of the structure of the thin film thickness measuring device provided by the present invention;

[0038] Figure 2 A schematic diagram of the detection fiber, objective lens probe, and optical path transmission under test provided by the present invention;

[0039] Figure 3 A schematic diagram of the first structure of the objective lens probe provided by the present invention and its annular optical ring;

[0040] Figure 4 A schematic diagram of a second structure of the objective lens probe provided by the present invention and its annular optical ring;

[0041] Figure 5 This invention provides schematic diagrams of the light spot images formed by the objective lens probe at the end face of the optical fiber of the light source under different measurement distances and in different situations; wherein... Figure 5 (a) is a schematic diagram of the light spot image formed by the objective lens probe on the end face of the light source fiber when measuring a distance of 1 in case A, and the back light image after reflection by the object to be measured. Figure 5 (b) is a schematic diagram of the light spot image formed by the objective lens probe on the end face of the optical fiber of the light source when measuring a distance of 2 in case B, and the reflected light image after being measured. Figure 5 (c) is a schematic diagram of the light spot image formed by the objective lens probe on the end face of the light source fiber when measuring a distance of 3 in case C, and the back light image after being reflected by the test object.

[0042] Figure 6 This is a schematic diagram of the reflected light image 2 at a distance of 2 and the position of the image relative to the Y-shaped multi-core fiber optic junction end, provided by the present invention.

[0043] Figure 7 This is a diagram showing the radial distribution of backlight energy at a measurement distance of 2, provided by the present invention.

[0044] Figure 8 This is a schematic diagram of the thin-film reflection model provided by the present invention;

[0045] Figure 9 A schematic diagram illustrating the difference in theoretical spectral reflectance at different incident angles for the same preset thickness, as provided by the present invention.

[0046] Figure 10 The noise spectrum, the reflection spectrum of the metal mirror, and the reflection spectrum of the thin film under test are obtained for the present invention.

[0047] Figure 11 A schematic diagram of the final obtained spectral reflectance provided by the present invention.

[0048] Symbol explanation:

[0049] 11-Light source, 12-Y-type multi-core optical fiber, 13-Objective lens probe, 14-Spectrometer, 15-Processor, 16-Thin film under test, 17-First spherical lens, 18-First conical lens, 19-Second spherical lens, 20-Second conical lens, 21-Fiber optic interface. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] The purpose of this invention is to provide a thin film thickness measuring device and method that can improve both the measurement efficiency and accuracy of thin film thickness.

[0052] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] like Figure 1 As shown, the thin film thickness measuring device provided by the present invention includes: a light source 11, a Y-type multi-core optical fiber 12, an objective lens probe 13, a spectrometer 14, and a processor 15.

[0054] Y-type multi-core optical fiber 12 is used for beam transmission, and it includes light source fiber 11 and multiple probe optical fibers.

[0055] One end of the optical fiber of the light source 11 is connected to the light source 11. The light source 11 is used to provide broadband wavelength incident light to the optical fiber of the light source 11, and the wavelength range can cover the ultraviolet, visible and near-infrared bands.

[0056] One end of each of the multiple probe fibers is connected to the spectrometer 14 so that the spectrometer 14 can detect the spectral information of the reflected light received by the probe fibers. The other end of the light source 11 fiber and the other ends of the multiple probe fibers converge at the same port to form a convergence end. In the convergence end, the light source 11 fiber is located at the center, and the probe fibers are arranged in a ring around the periphery of the light source 11 fiber. The convergence end is connected to the objective lens probe 13 to transmit the incident light from the light source 11 to the objective lens probe 13, and to receive the light (reflected light) from the objective lens probe 13 and transmit it to the spectrometer 14. For example, Figure 2 As shown, the optical fiber of the light source 11 is used to transmit incident light, and the optical fiber of the detector is used to transmit reflected light. The spectrometer 14 is electrically connected to the processor 15 so that the processor 15 can control the spectrometer 14 in real time and read the spectral signals therein, and solve the thickness of the thin film 16 under test through a calculation program.

[0057] Furthermore, in order to change the propagation direction of the incident and reflected light rays, the incident light from the optical fiber of the light source 11 is approximately converged onto the thin film 16 under test, and the reflected light is shaped into a Bessel ring 23 to obtain a ring-shaped backlight image (e.g., Figure 5 and Figure 6 As shown), for receiving by a ring-shaped array of detection optical fibers, the objective probe 13 used in this invention can employ two different structures to achieve imaging. One structure of the objective probe 13 includes: a first spherical lens 17, a first conical lens 18, a second spherical lens 19, a second conical lens 20, a fixing block 21, a cavity, and an optical fiber interface 22.

[0058] like Figure 3 As shown, the fiber optic interface 22, the first spherical lens 17, the first conical lens 18, the second spherical lens 19, and the second conical lens 20 are arranged along the same optical axis in the cavity, and the first spherical lens 17, the first conical lens 18, the second spherical lens 19, and the second conical lens 20 are all fixed in the cavity by the fixing block 21. The fiber optic interface 22 is located on the cavity wall. In practical applications, the conical surfaces of the first conical lens 18 and the second conical lens 20 can be symmetrical about the second spherical lens 19, but this arrangement will not have a significant impact on the conical imaging of the conical lens.

[0059] In another configuration of the objective lens probe 13, only the first cone lens 18 may be retained, for example, as shown below. Figure 4 As shown, its specific structure is as follows:

[0060] The fiber optic interface 22, the first spherical lens 17, the first conical lens 18, and the second spherical lens 19 are arranged along the same optical axis in the cavity, and the first spherical lens 17, the first conical lens 18, and the second spherical lens 19 are all fixed in the cavity by the fixing block 21. The fiber optic structure is arranged on the cavity wall.

[0061] However, in practical applications, different deformations may be used to achieve different effects of the annular light spot. For example, the cone surface of the first cone lens may be rotated, or the first cone lens may be placed to the right of the second spherical lens 19 (here, "right" refers to relative positioning). Figure 4 (Regarding page display)

[0062] In practical applications, the radius of the probe fiber is not less than the radius of the light source fiber. For example, when determining... Figure 5 When the radial distribution of the reflected light energy is shown at a measurement distance of 2, the diameter of the optical fiber in light source 11 can be 200 nm, the outer diameter can be 220 nm, the inner diameter of the outer ring that can receive light is 120 nm, and the outer diameter is 320 nm. At this time, as... Figure 7 As shown, the energy is mainly concentrated between the inner and outer rings of the ring-shaped distributed probe fiber end face, and this area between the inner and outer rings can be regarded as the energy concentration zone.

[0063] Furthermore, in this invention, the objective probe based on a combination of a conical lens and a spherical lens can focus point light onto the surface of the thin film under test, and then return to form a ring beam. This works well with the Y-type multi-core optical fiber, and controlling the objective probe 13 within a small range of incident angles is beneficial for light energy utilization and simplifies the thin film reflection model. The median value within the range is approximated as the incident angle of the objective probe 13.

[0064] Figure 6 In the diagram, A is the end face of the optical fiber for the light source 11, B is the end face of the optical fiber for the probe, and C is the end face of the junction.

[0065] Furthermore, to maximize the reception of reflected light from the linearly arranged probe fibers, the spectrometer 14 used in this invention is equipped with a slit structure at its front end. The slit structure is parallel to the linearly arranged probe fibers to receive the light from the probe fibers.

[0066] Furthermore, the processor 15 used in this invention is a system or device with an embedded intelligent processing chip, such as a computer.

[0067] The present invention also provides a method for measuring film thickness, applicable to the film thickness measuring apparatus provided above. The film thickness measuring method includes:

[0068] S1: Obtain the noise spectrum, the metal mirror reflection spectrum, and the thin film reflection spectrum, respectively. Figure 10 As shown. The specific implementation process of this step can be as follows:

[0069] S1-1: Without turning on the light source or placing the film (sample) to be tested, the processor controls the spectrometer to collect multiple sets of background noise signals over a certain period of time and performs average processing to obtain the noise spectrum I0(λ).

[0070] S1-2: Place the metal reflector at a suitable measurement distance in front of the objective lens probe, turn on the light source to generate broadband light that enters the light source fiber, and then approximately converge the light through the objective lens probe and incident on the metal reflector. The objective lens probe then shapes the reflected light into a ring beam and projects it onto the end face of the ring-arranged detection fiber.

[0071] S1-3: Using a spectrometer to receive light from linearly arranged probe fibers, obtain multiple sets of light intensity distribution signals of different wavelengths of metal mirrors within a certain time period, and perform average processing to obtain the reflection spectrum I1(λ) of the metal mirror.

[0072] S1-4: Replace the metal reflector with the film to be tested, place it in front of the objective lens probe at the same measurement distance as in S1-2, generate broadband light through the light source and enter the light source fiber, approximately converge the light through the objective lens probe and incident it on the film to be tested, and shape the reflected light into a ring beam through the objective lens probe and project it onto the end face of the ring-arranged probe fiber.

[0073] S1-5: Using a spectrometer to receive light from a linearly arranged probe fiber, the light intensity distribution signal of the thin film under test at different wavelengths is obtained in real time to obtain the reflection spectrum I2(λ) of the thin film under test.

[0074] S2: Determine the relative spectral reflectance of the thin film under test based on the noise spectrum, the reflection spectrum of the metal mirror, and the reflection spectrum of the thin film under test. The relative spectral reflectance of the thin film under test is R. 21 (λ): R 21 (λ)=(I2(λ)-I0(λ)) / (I1(λ)-I0(λ)).

[0075] S3: Determine the theoretical spectral reflectivity R1(λ,d1) of the metal mirror based on the incident angle of the objective lens probe, the optical constants of the metal and the coating of the metal mirror, and the preset coating thickness d1. For the same preset thickness, the difference in theoretical spectral reflectivity at different incident angles is as follows: Figure 9 As shown. Among them, based on as Figure 8 For the thin-film reflection model shown, the formula for calculating the theoretical spectral reflectivity of the metal mirror is:

[0076] n O sinθ = n1sinθ1;

[0077]

[0078]

[0079] Figure 8 In the formula, n0 is the air refractive index, k0 is the air extinction coefficient, n1 is the refractive index of the film under test, k1 is the extinction coefficient of the film under test, θ is the incident angle of the incident beam, θ1 is the refraction angle, and r all-s Let r be the reflection coefficient of all s-polarized reflected beams. 1s r1 is the value of r in the s-polarization state. 2s The value of r2 in the s-polarization state. r represents the phase difference between adjacent reflected beams. all-p Let r be the reflection coefficient of all p-polarized reflected beams. 1p r1 is the value of r in the p-polarized state. 2p R2 is the r2 value in the p-polarized state, λ is the wavelength, h is the film thickness, and R2 is the film thickness. film R represents the spectral reflectance of the thin film.s R is the reflectivity of the s-polarized state. p Let be the reflectivity of the p-polarized state.

[0080] The above formula is the specific derivation process of Fresnel's formula. For details, please refer to the relevant content in "Engineering Optics". It will not be repeated here.

[0081] S4: Based on the theoretical spectral reflectivity of the metal mirror and the relative spectral reflectivity of the thin film under test, determine the absolute spectral reflectivity of the thin film under test. The absolute spectral reflectivity of the thin film under test is R²(λ): R²(λ) = R 21 (λ)×R1(λ,d1).

[0082] S5: Based on the optical constants of the substrate and coating of the thin film under test, and the preset film thickness d2, determine the theoretical spectral reflectance R of the thin film under test. 2理 (λ,d2).

[0083] S6: Determine the goodness of fit between the theoretical spectral reflectance and the absolute spectral reflectance of the film under test. That is, use a computer to solve for the theoretical spectral reflectance R of the film under test at a preset film thickness d2. 2理 (λ,d2) is compared with the absolute spectral reflectance R2(λ) mentioned above.

[0084] S7: When the fit reaches the preset requirement, the preset film thickness d2 is determined as the thickness of the film to be measured. Specifically, using both the preset metal mirror coating thickness d1 and the preset film thickness d2 as parameters, an optimization inversion solution is performed to obtain the preset film thickness d2 at which the fit is optimal. The preset film thickness d2 at which the fit is optimal is the thickness of the film to be measured.

[0085] The coating thickness d1 of the metal mirror can be obtained by means of SEM or step instrument, or by using the coating thickness d1 of the metal mirror and the preset thin film thickness d2 as parameters to solve the objective function optimization problem.

[0086] The final obtained spectral reflectance is as follows Figure 11 As shown, d1 and d2 are used as parameters for optimization, and R2(λ) and R... 2理 Using the sum and variance of (λ,d2) as the objective function, we finally obtain d1 and d2 when the objective function is minimized.

[0087] In the above method, by using a common metal reflective mirror for comparison, it is only necessary to know the coating thickness parameter or use it as one of the optimization targets, so as to obtain its theoretical spectral reflectance at a specific incident angle. This is used to correct the relative spectral reflectance of the film under test and obtain its absolute spectral reflectance. Finally, the thickness of the film under test is obtained by fitting. This method can ensure the uniformity of the incident angle throughout the solution process, has better traceability, and better fitting results.

[0088] Based on the above description, the present invention has the following advantages compared to the prior art:

[0089] 1. Based on the imaging characteristics of conical lenses and spherical lenses, this invention designs an objective lens probe with a shared optical path for incident and reflected light. It can shape the outgoing light from the end face of the circular light source fiber into an approximate focus on the surface to be measured, and the incident angle range is small, which is beneficial to simplify the reflection model. Moreover, it can shape the reflected light into a ring-shaped backlight image, which matches well with the Y-type multi-core fiber confluence end. Most of the reflected light enters the ring-shaped probe fiber end face, and the reflected light is prevented from entering the light source fiber end face, which greatly improves the light energy utilization rate. The overall structure is simple, modularly assembled, and highly integrated.

[0090] 2. This invention uses a metal reflective mirror for comparison, and utilizes its surface characteristics to obtain the theoretical spectral reflectance at the incident angle corresponding to this device, thereby obtaining a more accurate absolute spectral reflectance of the surface to be measured, enhancing the traceability of the measurement results and helping to improve the measurement accuracy.

[0091] 3. The lenses, optical fibers, metal mirrors and other devices used in this invention have low cost, and the measurement process is highly operable, with simple algorithm programs that are easy to commercially develop and promote.

[0092] Furthermore, the aforementioned thin film thickness measurement method can be embedded into a software functional unit as a computer program. When implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the aforementioned thin film thickness measurement method of the present invention, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0094] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A thin film thickness measuring device, characterized in that, include: Light source, Y-type multi-core optical fiber, objective lens probe, spectrometer, and processor; The Y-type multi-core optical fiber includes a light source fiber and multiple probe fibers; One end of the light source optical fiber is connected to the light source; one end of the multiple detection optical fibers is arranged in a straight line and connected to the spectrometer; the other ends of the multiple detection optical fibers are arranged circumferentially with the other end of the light source optical fiber as the center; the other end of the light source optical fiber and the other ends of the multiple detection optical fibers form a confluence and are connected to the objective lens probe; the spectrometer is electrically connected to the processor. To change the propagation direction of the incident and reflected light, the incident light from the light source fiber is focused onto the thin film under test, and the reflected light is shaped into a Bessel ring to obtain a ring-shaped backlight image for reception by the ring-arranged detection fibers; the objective lens probe includes: a first spherical lens, a first conical lens, a second spherical lens, a fixing block, a cavity, and an optical fiber interface. The fiber optic interface, the first spherical lens, the first conical lens, and the second spherical lens are arranged sequentially along the same optical axis, and the first spherical lens, the first conical lens, and the second spherical lens are all fixed in the cavity by the fixing block.

2. The thin film thickness measuring device according to claim 1, characterized in that, The objective lens probe also includes: a second conical lens; The fiber optic interface, the first spherical lens, the first conical lens, the second spherical lens, and the second conical lens are arranged along the same optical axis, and the first spherical lens, the first conical lens, the second spherical lens, and the second conical lens are all fixed in the cavity by the fixing block.

3. The thin film thickness measuring device according to claim 1, characterized in that, The spectrometer is equipped with a slit structure; the slit structure is parallel to the linearly arranged detection optical fibers to receive light from the detection optical fibers.

4. The thin film thickness measuring device according to claim 1, characterized in that, The processor is a system or device with an embedded intelligent processing chip.

5. The thin film thickness measuring device according to claim 1, characterized in that, The radius of the detection optical fiber is not less than the radius of the light source optical fiber.

6. A method for measuring thin film thickness, characterized in that, Applied in the thin film thickness measuring device as described in any one of claims 1-5; The thin film thickness measurement method includes: The noise spectrum, the metal mirror reflection spectrum, and the thin film under test were obtained respectively. The relative spectral reflectivity of the thin film under test is determined based on the noise spectrum, the reflection spectrum of the metal mirror, and the reflection spectrum of the thin film under test. The theoretical spectral reflectivity of the metal mirror is determined based on the incident angle of the objective lens probe, the optical constants of the metal and the coating of the metal mirror, and the preset coating thickness d1 of the metal mirror. The absolute spectral reflectance of the thin film under test is determined based on the theoretical spectral reflectance of the metal mirror and the relative spectral reflectance of the thin film under test. Based on the optical constants of the substrate and coating of the thin film under test, and the preset film thickness d2, the theoretical spectral reflectance of the thin film under test is determined. Determine the goodness of fit between the theoretical spectral reflectance and the absolute spectral reflectance of the thin film under test; When the fitting degree reaches the preset requirement, the preset film thickness d2 is determined as the thickness of the film to be measured; specifically, the preset metal mirror coating thickness d1 and the preset film thickness d2 are used as parameters to perform the fitting degree optimization inversion solution to obtain the preset film thickness d2 when the fitting degree is optimal; the preset film thickness d2 when the fitting degree is optimal is the thickness of the film to be measured.

7. The thin film thickness measurement method according to claim 6, characterized in that, The noise spectrum, the metal mirror reflection spectrum, and the thin film under test were acquired separately, specifically including: Without turning on the light source or placing the film to be tested, multiple sets of background noise signals are acquired within a set time period, and the multiple sets of background noise signals are averaged to obtain the noise spectrum; The metal reflector is placed at a preset distance from the objective lens probe, and the light source is turned on to obtain the first light intensity distribution signal; the first light intensity distribution signal is the light intensity distribution signal of the metal reflector at different wavelengths within a set time after the light source is turned on. The reflection spectrum of the metal mirror is obtained by averaging the first light intensity distribution signal. Replace the metal reflector with the film to be tested, and place the film to be tested at a preset distance from the objective lens probe. Turn on the light source to obtain a second light intensity distribution signal. The second light intensity distribution signal is the light intensity distribution signal of the film to be tested at different wavelengths within a set time after the light source is turned on. The reflection spectrum of the thin film under test is obtained by averaging the second light intensity distribution signal.

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