Thickness measuring device and thickness measuring method

Abstract

The application provides a thickness measuring device and a thickness measuring method. The thickness measuring device comprises: a light source, which forms an incident light beam incident to a first surface of a sample, the incident light beam is reflected on the first surface to form a reflected light beam, the incident light beam is transmitted through the sample and scattered on a second surface of the sample to form a scattered light beam, wherein the first surface and the second surface are opposite; a beam combination module, which combines the reflected light beam and the scattered light beam into a coherent light beam; a reflected light path, which guides the reflected light beam into the beam combination module; a scattered light path, which guides the scattered light beam into the beam combination module; and a detection module, which is used to obtain the coherent light beam to obtain the thickness of the sample. The application realizes high-precision measurement of the thickness of a sample with one smooth surface and the other opposite surface being rough.

Description

Technical Field

[0001] This invention relates to the field of thickness measurement, and more particularly to a thickness measuring device and a thickness measuring method. Background Technology

[0002] In the field of thickness measurement, it may be necessary to measure samples with certain characteristics, such as samples with one smooth surface and another rough surface. For example, in the semiconductor field, it may be necessary to measure the thickness of a single-layer polished wafer. Existing measurement methods include... Figure 1 As shown, a broadband light source illuminates the surface of sample 16B (single-polished wafer) to form incident light 11. The upper surface is polished, and the lower surface is unpolished / rough. The incident light 11 is directly reflected by the sample surface to form reflected light 12. Simultaneously, after the incident light 11 illuminates the sample, it forms refracted light 13. The refracted light 13 is scattered on the unpolished surface of the sample to form scattered light 14. The scattered light 14 is again refracted by the sample surface to form secondary refracted light 15. The coherent light formed by the reflection light 12 and the secondary refracted light 15 reaches the spectrometer 17. Because the directionality of the scattered light from the unpolished surface is much lower than that of the reflected light from the polished surface, the intensity of the secondary refracted light 15 is extremely low. The spectrometer 17 usually cannot obtain coherent light of sufficient intensity, resulting in a low signal-to-noise ratio and spectral distortion, which makes it impossible to complete thickness measurement or achieve high-precision thickness measurement.

[0003] If Figure 1 The incident light shown was adjusted to be incident from the lower surface of sample 16B. The incident light underwent diffuse reflection at the incident surface, and the intensity of the collected diffuse reflection signal was low, resulting in a very low signal-to-noise ratio for the acquired coherent light.

[0004] Furthermore, for wafers doped with ions, the above measurement method has the following drawbacks: regardless of whether the light beam of the light source is incident from the polished surface or the rough surface, the light signal of the refracted light propagating twice in the wafer thickness direction is affected by the uniformity of the wafer dopant ion concentration. The coherent light contains a longer optical path light signal affected by the dopant ions, which further reduces the accuracy of measuring the wafer thickness.

[0005] Therefore, existing technologies suffer from low signal-to-noise ratio, spectral distortion, low measurement accuracy, and even the inability to complete thickness measurement, which are technical problems that urgently need to be solved in this field. Summary of the Invention

[0006] In order to overcome the defects of the above-mentioned related technologies, the present invention provides a thickness measuring device and a thickness measuring method, which can solve the problems of the prior art and realize high-precision measurement of the thickness of a sample with one surface being smooth and the other surface being rough.

[0007] According to one aspect of the present invention, a thickness measuring device is provided, comprising:

[0008] A light source forms an incident light beam that is incident on a first surface of the sample. The incident light beam is reflected on the first surface to form a reflected light beam, and the incident light beam is transmitted through the sample and scattered on a second surface of the sample to form a scattered light beam, wherein the first surface and the second surface are opposite to each other.

[0009] The beam combining module combines the reflected beam and the scattered beam into a coherent beam;

[0010] The reflected light path guides the reflected light beam into the beam combining module;

[0011] The scattered light path guides the scattered light beam into the beam combining module;

[0012] A detection module is used to acquire the coherent beam to obtain the thickness of the sample.

[0013] In some embodiments of this application, the reflected light path includes a light intensity filter element, which is used to filter out the light transmitted from the first surface after the incident light beam reaches the second surface.

[0014] In some embodiments of this application, the reflected optical path includes a first optical fiber or a first optical fiber and a first focusing element, wherein the first focusing element couples the reflected beam to the first optical fiber;

[0015] The scattering optical path includes a second optical fiber or a second optical fiber and a second focusing element, wherein the second focusing element couples the scattered beam to the second optical fiber;

[0016] The beam combining module includes a coupler that couples the first optical fiber and the second optical fiber to a third optical fiber, and the coherent beam is output from the third optical fiber.

[0017] In some embodiments of this application, the reflected optical path includes at least one reflective element;

[0018] The scattering optical path includes a second focusing element;

[0019] The beam combining module includes a beam combiner, and the reflected beam and the scattered beam are combined by the beam combiner to output the coherent beam.

[0020] In some embodiments of this application, the scattered beam is Rayleigh scattering and / or Mie scattering.

[0021] In some embodiments of this application, the difference between the wavelength of the incident light beam and the particle diameter of the second surface is less than a set threshold; or, the wavelength of the incident light beam is changed to maximize the light intensity of the scattered light beam.

[0022] In some embodiments of this application, the light source is a broadband light source or a monochromatic light source, the detection module is a spectrometer or a light intensity detector, and the incident beam is a linear beam or a columnar single beam.

[0023] According to another aspect of this application, a thickness measurement method is also provided, applied to the thickness measurement device described above, the thickness measurement method comprising:

[0024] The light source is configured to form an incident beam that is incident on the first surface of the sample;

[0025] The coherent beam is obtained through the beam combining module;

[0026] The thickness of the sample is obtained by analyzing the coherent spectrum of the coherent beam.

[0027] In some embodiments of this application, it also includes:

[0028] Adjust the reflected light path to maximize the light intensity of the reflected beam introduced into the beam combining module;

[0029] Adjust the scattering light path to maximize the light intensity of the scattered beam introduced into the beam combining module.

[0030] In some embodiments of this application, the light source is a broadband light source, and in response to the broadband light source, the detection module outputs the coherent spectrum, analyzes the coherent spectrum, and obtains the thickness of the sample;

[0031] Alternatively, the light source may be multiple monochromatic light sources, each responding to a different monochromatic light source. The detection module outputs multiple coherent light intensities, which together constitute the coherent spectrum. By analyzing the coherent spectrum, the thickness of the sample can be obtained.

[0032] Compared with the prior art, the advantages of this invention are:

[0033] The thickness of the sample is obtained by detecting the incident light beam incident on the first surface of the sample, the reflected light beam formed by the reflection of the incident light beam on the first surface, and the scattered light beam formed by the incident light beam passing through the sample and being scattered on the second surface of the sample. This allows for high-precision measurement of the thickness of a sample with one smooth surface and the other rough surface. Attached Figure Description

[0034] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0035] Figure 1 A schematic diagram of a thickness measuring device in the background art is shown.

[0036] Figure 2 A schematic diagram of a thickness measuring device according to a first embodiment of the present invention is shown.

[0037] Figure 3 A schematic diagram of a thickness measuring device according to a second embodiment of the present invention is shown.

[0038] Figure 4 A schematic diagram of a thickness measuring device according to a third embodiment of the present invention is shown.

[0039] Figure 5 A flowchart of a thickness measurement method according to an embodiment of the present invention is shown. Detailed Implementation

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, these example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details described, or other methods, materials, apparatus, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring aspects of this disclosure. The same reference numerals in the figures denote the same or similar structures, and therefore their detailed descriptions are omitted.

[0041] The terms “a,” “one,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “including,” “having,” and “have” are used to indicate an open-ended inclusion meaning and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0042] This invention provides a thickness measuring device and a thickness measuring method, enabling high-precision measurement of the thickness of a sample with one smooth surface and the other rough surface.

[0043] First see Figure 2 , Figure 2A schematic diagram of a thickness measuring device according to a first embodiment of the present invention is shown. The thickness measuring device 200A includes a light source 210, a beam combining module 260, a reflected light path 240, a scattered light path 250, and a detection module 270. The sample 230 to be measured includes a first surface 231 and a second surface 232 facing away from each other. The first surface 231 of the sample 230 may be, for example, a smooth surface, and the second surface 232 of the sample 230 may be, for example, an unpolished / rough surface. This application is not limited thereto, and the thickness measurement of other types of samples 230 (such as those where both the first surface 231 and the second surface 232 are smooth surfaces, or both the first surface 231 and the second surface 232 are unpolished / rough surfaces) is also within the scope of protection of this application.

[0044] The light source 210 forms an incident light beam 221 that is incident on the first surface 231 of the sample 230. The incident light beam 221 is reflected at the first surface 231 to form a reflected light beam 222. The incident light beam 221 is refracted at the first surface 231 of the sample 230 to form a refracted light beam 223, and scattered at the second surface 232 of the sample 230 to form a scattered light beam 224.

[0045] The reflected light path 240 guides the reflected light beam 222 into the beam combining module 260.

[0046] The scattering light path 250 guides the scattered beam 224 into the beam combining module 260.

[0047] The beam combining module 260 combines the reflected beam 222 and the scattered beam 224 into a coherent beam 225.

[0048] The detection module 270 is used to acquire the coherent beam 225 to obtain the thickness of the sample 230.

[0049] Therefore, the thickness measuring device provided in this application obtains the thickness of the sample by detecting the incident light beam incident on the first surface of the sample, the reflected light beam formed by the reflection of the incident light beam on the first surface, and the scattered light beam formed by the incident light beam passing through the sample and being scattered on the second surface of the sample. This coherent light beam allows for high-precision measurement of the thickness of samples with one smooth surface and the other rough surface. Furthermore, for samples containing doped ions, the coherent light beam detected in this embodiment does not involve secondary refraction, thereby reducing the influence of the uniformity of the doped ion concentration in the sample and further improving the measurement accuracy of the sample thickness.

[0050] In some embodiments, the reflected optical path 240 may include an intensity filter element, which is used to filter out the light (secondary refracted light) transmitted from the first surface 231 after the incident beam 221 reaches the second surface 232. Since the light transmitted from the first surface 231 after the incident beam 221 reaches the second surface 232 is almost coaxial with the reflected beam 222, and its intensity is relatively weak, the intensity filter element can effectively filter out the light transmitted from the first surface 231 after the incident beam 221 reaches the second surface 232, thereby improving the signal-to-noise ratio of the coherent beam 225 obtained by the measurement and detection module 270.

[0051] In some embodiments, the first surface 231 of the sample 230 is a smooth surface, and the second surface 232 is an unpolished / rough surface. In some variations, both the first and second surfaces of the sample are polished smooth surfaces. In this case, the scattered light path 250 can be shielded, and the coherent beam of the reflected light beam 222 obtained by the reflected light path 240 and the light transmitted from the first surface 231 after the incident light beam 221 reaches the second surface 232 (secondary refracted light) is guided to the detection module 270 to obtain the thickness of the sample. Thus, the thickness measurement device provided in this application is compatible with the thickness measurement of different types of samples.

[0052] See below. Figure 3 , Figure 3 A schematic diagram of a thickness measuring device according to a second embodiment of the present invention is shown. The thickness measuring device 220B includes a light source 210, a beam combining module 260A, a reflected light path, a scattered light path, and a detection module 270, and a data processing unit 280 connected to the detection module 270. The sample 230 to be measured includes a first surface 231 and a second surface 232 facing away from each other.

[0053] In this embodiment, the reflected light path may include a first optical fiber 243. The scattered light path may include a second optical fiber 253. The beam combining module 260A includes a coupler that couples the first optical fiber 243 and the second optical fiber 253 to a third optical fiber 261, and the coherent light 225 is output from the third optical fiber 261. In some specific embodiments, the reflected light path may also include a first focusing element 242, which couples the reflected beam 222 to the first optical fiber 243. The first focusing element 242 may include a lens element and / or a self-focusing lens disposed at the light input end of the first optical fiber 243 to improve the fiber coupling efficiency. In some specific embodiments, the scattered light path may also include a second focusing element 251, which couples the scattered beam 224 to the second optical fiber 253. The second focusing element 251 may include a lens element and / or a self-focusing lens disposed at the light input end of the second optical fiber 253 to improve the fiber coupling efficiency. The coupler can be a fused biconical tapered coupler or a planar waveguide coupler, but this application is not limited to these.

[0054] In this embodiment, the reflected light path may include an intensity filter element 241, which is used to filter out the light (secondary refracted light) transmitted from the first surface 231 after the incident light beam 221 reaches the second surface 232. Further, after being filtered by the intensity filter element 241, the reflected light beam 222 is coupled to the first optical fiber 243 through the first focusing element 242.

[0055] In addition, such as Figure 3 As shown, the coherent light 255 emitted from the third optical fiber 261 is received by the detection module 270 after passing through the reflector 290. This is not a limitation on the way the detection module receives coherent light; for example, the third optical fiber 261 can also be directly connected to the input port of the detection module 270 to enable the detection module 270 to receive coherent light 255.

[0056] See below. Figure 4 , Figure 4 A schematic diagram of a thickness measuring device according to a third embodiment of the present invention is shown. The thickness measuring device 200C includes a light source 210, a beam combining module 260B, a reflected light path, a scattered light path, and a detection module 270, and a data processing unit 280 connected to the detection module 270. The sample 230 to be measured includes a first surface 231 and a second surface 232 facing away from each other.

[0057] In this embodiment, the reflected optical path may include at least one reflective element. For example... Figure 4As shown, the reflected light path may include reflective elements 244 and 245. The scattered light path may include a second focusing element 252. The beam combining module 260B may include a beam combiner, through which the reflected beam 222 and the scattered beam 224 are combined to output the coherent beam 225.

[0058] In this embodiment, the reflected light path may include an intensity filter element 241, which is used to filter out the light (secondary refracted light) transmitted from the first surface 231 after the incident light beam 221 reaches the second surface 232. Further, the reflected light beam 222, after being reflected by reflective elements 244 and 245, is filtered by the intensity filter element 241 and then guided to the beam combining module 260B.

[0059] In addition, such as Figure 4 As shown, the coherent light 225 output by the beam combining module 260B is reflected by the reflector 290 and then received by the detection module 270. This is not a limitation on the way the detection module receives the coherent light; for example, the coherent light 225 can be directly input to the input port of the detection module, or the coherent light can be directly coupled to the input port of the detection module after passing through the focusing unit, so that the detection module 270 can receive the coherent light 225.

[0060] The above are merely illustrative examples of several embodiments of this application, and this application is not intended to limit it. Each embodiment can be implemented individually or in combination.

[0061] In some embodiments, such as Figure 3 and Figure 4 The light source 210 can be a broadband light source, thereby allowing the coherent beam 225 to illuminate the reflective element 290 with a grating, thus dividing it into reflected beams with different reflection angles determined by the wavelength. These reflected beams reach the detection module 270 for acquisition. The detection module 270 is an array of detectors, thereby obtaining the coherent spectrum of the coherent light. Alternatively, the reflective element 290 can be a common mirror, serving only to reflect the coherent light. Correspondingly, the detection module 270 can be a spectrometer, thus obtaining the spectrum of the coherent light based on the detected coherent beam 225. The data processing unit 280 connected to the detection module 270 can fit the spectrum of the coherent beam 225 with a known spectrum to obtain the sample thickness. In this embodiment, the light intensity filter element 241 can be a polychromatic light intensity filter element to adapt to the broadband light source, filtering out secondary refracted light to enhance the signal-to-noise ratio of the coherent beam. In some embodiments, the wavelength of the broadband light source is adjustable.

[0062] In some variations, the light source can be multiple monochromatic light sources, and the detection module can be a light intensity detector. The light intensity detector can detect the light intensity of the coherent beam, thereby obtaining the discrete spectrum of the coherent beam (where wavelength is a discrete point in the "reflectivity-wavelength" spectrum), that is, combining the light intensities of the coherent beams corresponding to all monochromatic light sources to obtain the coherent spectrum / discrete spectrum. Therefore, the data processing unit connected to the detection module can fit the discrete spectrum of the coherent beam 225 with a known spectrum to obtain the sample thickness. In this embodiment, the light intensity filter element can be a monochromatic light intensity filter element to adapt to the monochromatic light source and filter out secondary refracted light to enhance the signal-to-noise ratio of the coherent beam.

[0063] In some embodiments, the incident beam can be a line beam to measure the thickness of a line segment of the sample. The incident beam can also be a cylindrical single beam to measure the thickness of the closed region formed by the projection of the cylindrical beam onto the sample. When the incident beam is a line beam, the focusing element used in the reflected and / or scattered light paths can be a cylindrical mirror, the optical fiber used in the reflected and / or scattered light paths can be a close-packed optical fiber, and the detection module used in the thickness measurement device can be an array spectrometer. Alternatively, the entire surface of the sample can be scanned to obtain the thickness at all locations on the sample surface.

[0064] When adopting such Figure 1 The thickness measurement device shown, when measuring wafers with inconsistent polishing levels on the upper and lower surfaces (such as a single-polished wafer 16B), suffers from a significant decrease in intensity of secondary refracted light 15 compared to double-polished wafers (not shown). This is because the directionality of scattered light from the unpolished surface is much lower than that of reflected light from the polished surface. Consequently, the signal-to-noise ratio (SNR) of the coherent light from the single-polished wafer fails to meet the standard required for wafer thickness identification. Specifically, if the light beam from the light source is incident from the polished surface of the wafer, collecting both reflected and secondary refracted light: the secondary refracted light signal is too weak when measuring a single-polished wafer, resulting in a low SNR and spectral distortion. If the light beam is incident from the rough surface of the wafer, the reflected light is diffusely reflected, leading to a low signal intensity. Furthermore, inverting the wafer to improve the SNR, with the polished surface facing down, can easily damage the polished surface.

[0065] To improve the signal-to-noise ratio and signal intensity of the coherent beam, in some embodiments of this application, the scattered beam 224 can be Rayleigh scattering and / or Mie scattering. The phases of Rayleigh and Mie scattering differ due to variations in sample thickness. Therefore, coherently scattering the Rayleigh and / or Mie scattering with the reflected beam results in a coherent beam containing sample thickness information. The detection module can then obtain the coherent light spectrum, which, after fitting with the theoretical spectrum or calibrating with a spectral library, yields the thickness value of the polished wafer.

[0066] Scattering is categorized into elastic scattering and inelastic scattering based on whether the wavelength of the scattered beam changes. Elastic scattering occurs when the wavelength remains constant. Elastic scattering is further classified into Rayleigh scattering and Mie scattering based on the relative size of the wavelength and the particle size. Mie scattering exhibits stronger directionality, with the greatest intensity of scattered light along the optical axis. Therefore, in some preferred embodiments, Mie scattering, which maximizes the intensity along the optical axis, can be used to obtain a coherent beam with higher intensity, further improving the spectral signal-to-noise ratio. Furthermore, this method eliminates the need for sample inversion, avoiding contact between the polished surface and the stage.

[0067] The resulting wear and tear.

[0068] Furthermore, when the difference between the wavelength of the incident beam and the diameter of the particles or rough particles on the second surface is less than a set threshold (i.e., the wavelength of the incident beam is comparable to the diameter of the particles or rough particles on the second surface), the intensity of the scattered beam along the optical axis can be maximized, resulting in a higher-intensity coherent beam that further improves the spectral signal-to-noise ratio. Simultaneously, it eliminates the need to invert the sample, avoiding wear caused by contact between the polished surface and the stage. Specifically, the diameter of the particles or rough particles on the second surface can be obtained using measuring equipment such as an atomic force microscope or interferometer, or it can be determined based on the particle or rough particle diameter range provided at the time of sample delivery. In other variations, the wavelength of the incident beam can be changed to maximize the intensity of the scattered beam, thus using that wavelength as the wavelength of the incident beam. The wavelength of the incident beam can be changed by replacing it with a different light source, or by selecting a broadband light source with an adjustable wavelength band and adjusting the wavelength of the emitted light. This application is not limited to these methods, and other methods for changing the wavelength of the incident beam are not described in detail here, as long as the wavelength of the incident beam can be changed to maximize the intensity of the scattered beam. The content disclosed in the above embodiments can be flexibly applied to different samples to ensure that a sufficiently strong scattered signal is obtained, thereby improving the signal-to-noise ratio of the light signal acquired by the detection module.

[0069] Furthermore, in the above embodiments, taking sample 230 as a single-polished wafer as an example, the first surface 231 of the single-polished wafer is a polished surface, and the second surface 232 of the single-polished wafer is an unpolished surface, a rough surface, or a surface with particles / rough particles. This single-polished wafer sample is not limited to the embodiments of this disclosure. For other samples with similar properties, such as films, sheets, and substrates with microstructures on one side, the embodiments of this disclosure can also achieve the same technical effects. Accordingly, when sample 230 is a single-polished silicon wafer, the light source is preferably in the infrared band to ensure good transmission of sample 230; when sample 230 is made of other materials, a light source with good light transmittance to sample 230 is selected based on the light transmittance of the sample.

[0070] This application also provides a thickness measurement method, which measures the sample thickness based on the above-mentioned thickness measurement device. Figure 5 A flowchart of a thickness measurement method according to an embodiment of the present invention is shown. The thickness measurement method includes:

[0071] Step S110: The light source forms an incident beam that is incident on the first surface of the sample;

[0072] Step S120: Obtain the coherent beam through the beam combining module;

[0073] Step S130: Analyze the coherent spectrum of the coherent beam to obtain the thickness of the sample.

[0074] Therefore, the thickness measurement method provided in this application obtains the sample thickness by detecting the incident light beam incident on the first surface of the sample, the reflected light beam formed by the reflection of the incident light beam on the first surface, and the scattered light beam formed by the incident light beam passing through the sample and being scattered on the second surface of the sample. This coherent beam is then used to obtain the sample thickness, thereby achieving high-precision measurement of the thickness of samples with one smooth surface and the other rough surface. Furthermore, for samples containing doped ions, since the coherent beam detected for thickness measurement does not involve secondary refraction, the influence of the uniformity of doped ion concentration in the sample is reduced, further improving the measurement accuracy of the sample thickness.

[0075] In some embodiments, the above method may further include: adjusting the reflected light path to maximize the light intensity of the reflected light beam introduced into the beam combining module; and adjusting the scattered light path to maximize the light intensity of the scattered light beam introduced into the beam combining module.

[0076] In a specific embodiment, the reflected optical path may include an intensity filter element, which is used to filter out the light (secondary refracted light) transmitted from the first surface after the incident beam reaches the second surface. Since the light (secondary refracted light) transmitted from the first surface after the incident beam reaches the second surface is almost coaxial with the reflected beam, using an intensity filter element can effectively filter out the light transmitted from the first surface after the incident beam reaches the second surface, thereby improving the signal-to-noise ratio of the coherent beam obtained by the measurement and detection module.

[0077] In some embodiments, the steps of placing the sample and calibrating the focal plane are included before step S110.

[0078] In some embodiments, after step S110 and before step S120, the following steps are further included: adjusting the reflected light path (e.g., adjusting the optical elements of the reflected light path, such as the reflective elements and / or focusing elements in the above embodiments), to maximize the detection signal acquired by the detection module / maximize the light intensity of the reflected beam introduced into the beam combining module; performing light intensity shielding on the reflected light path, increasing the power of the light source, to maximize the detection signal acquired by the detection module / maximize the light intensity of the scattered beam introduced into the beam combining module (e.g., by adjusting the optical elements of the scattered light path and / or the beam combining module); removing the light intensity shielding on the reflected light path, adjusting the light intensity filter element of the reflected light path, to maximize the detection signal acquired by the detection module. Through the above steps, the intensity of the obtained reflected beam and scattered beam can be increased, thereby improving the signal-to-noise ratio of the detection signal / coherent beam acquired by the detection module and improving the thickness measurement accuracy.

[0079] In some embodiments, the light source is a broadband light source, and in response to the broadband light source, the detection module outputs the coherent spectrum, analyzes the coherent spectrum, and obtains the thickness of the sample.

[0080] In some embodiments, the light source is a plurality of monochromatic light sources. In response to each monochromatic light source, the detection module outputs a plurality of coherent light intensities. The plurality of coherent light intensities constitute the coherent spectrum. The thickness of the sample is obtained by analyzing the coherent spectrum.

[0081] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the icon's arrangement is flipped so that it is upside down, the component described as "up" will become the component described as "down." Other relative terms such as "high," "low," "top," "bottom," "left," and "right" also have similar meanings. When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0082] In the description of this specification, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A thickness measuring device, characterized by, The thickness measurement device comprises: a light source, which forms an incident light beam incident to a first surface of a sample, the incident light beam reflects on the first surface to form a reflected light beam, the incident light beam transmits through the sample and scatters on a second surface of the sample to form a scattered light beam, wherein the first surface and the second surface are opposite to each other; a beam combination module, which combines the reflected light beam and the scattered light beam into a coherent light beam; a reflected light path, which guides the reflected light beam to the beam combination module; a scattered light path, which guides the scattered light beam to the beam combination module; a detection module, which acquires the coherent light beam to obtain the thickness of the sample.

2. The thickness measuring device of claim 1, wherein The reflected light path comprises a light intensity filter element, which filters the light transmitted from the first surface after the incident light beam reaches the second surface.

3. The thickness measuring device according to claim 1 or 2, characterized in that The reflected light path comprises a first optical fiber or a first optical fiber and a first light focusing element, which couples the reflected light beam to the first optical fiber. The scattered light path comprises a second optical fiber or a second optical fiber and a second light focusing element, which couples the scattered light beam to the second optical fiber. The beam combination module comprises a coupler, which couples the first optical fiber and the second optical fiber to a third optical fiber, and the coherent light beam is output from the third optical fiber.

4. The thickness measuring device according to claim 1 or 2, characterized in that The reflected light path comprises at least one reflecting element. The scattered light path comprises a second light focusing element. The beam combination module comprises a beam combiner, and the reflected light beam and the scattered light beam are output as the coherent light beam after passing through the beam combiner.

5. The thickness measuring device of claim 1, wherein, The scattered light beam is Rayleigh scattering and / or Mie scattering.

6. The thickness measurement device according to claim 1, wherein: a difference between a wavelength of the incident light beam and a particle diameter of the second surface is less than a set threshold; or the wavelength of the incident light beam is changed so that the light intensity of the scattered light beam is maximum.

7. The thickness measuring device of claim 1, wherein, The light source is a broadband light source or a monochromatic light source, the detection module is a spectrometer or a light intensity detector, and the incident light beam is a linear light beam or a columnar single beam.

8. A thickness measurement method applied to the thickness measurement apparatus according to any one of claims 1 to 7, characterized by, The thickness measurement method comprises: the light source forms an incident light beam incident to a first surface of a sample; the beam combination module acquires the coherent light beam; the coherent spectrum of the coherent light beam is analyzed to obtain the thickness of the sample.

9. The thickness measurement method according to claim 8, wherein, Further comprising: the reflected light path is adjusted so that the light intensity of the reflected light beam guided to the beam combination module is maximum; the scattered light path is adjusted so that the light intensity of the scattered light beam guided to the beam combination module is maximum.

10. The thickness measurement method according to claim 8, wherein: the light source is a broadband light source, and the detection module outputs the coherent spectrum in response to the broadband light source, analyzes the coherent spectrum, and obtains the thickness of the sample; or, the light source is a plurality of monochromatic light sources, and the detection module outputs a plurality of coherent intensities in response to each monochromatic light source, the plurality of coherent intensities constitute the coherent spectrum, and the coherent spectrum is analyzed to obtain the thickness of the sample.

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