Spectral measurement system and spectral thickness measurement system

Abstract

The present invention provides a spectral measurement system and a spectral thickness measurement system. The spectral measurement system includes a light source module, a dispersive element, a detector, a displacement stage controller, and a displacement stage. The light source module provides incident light, which irradiates a first region on the sample to generate a first interference light, which is incident on the detector via the dispersive element to generate a first coherent spectrum. The displacement stage controller controls the displacement stage to move the sample so that the incident light irradiates a second region on the sample to generate a second interference light, the second and first regions partially overlap, the second interference light is incident on the detector via the dispersive element to generate a second coherent spectrum, and the first coherent spectrum is compensated based on the second coherent spectrum. The spectral thickness measurement system includes the spectral measurement system and obtains the thickness of the first region based on a spectral database and the compensated first coherent spectrum. The present invention moves the position of the sample by the displacement stage and compensates for spectral information on the sample that is lost due to the limitations of the spatial resolution of the detector.

Description

[Technical Field]

[0001] This invention relates to the field of optical measurement, and more specifically to spectral measurement systems and spectral thickness measurement systems. [Background technology]

[0002] A spectral measurement system can measure the spectrum of a sample. When a spectral measurement system is used to measure the thickness of a sample, it is called a spectral thickness measurement system. A spectral thickness measurement system can obtain the thickness of a sample based on its spectrum, and this thickness may be the film thickness on the sample or the absolute thickness of the sample. An existing linear light source spectral thickness measurement system is shown in Figure 1, and this spectral thickness measurement system mainly includes a linear light source, a beam splitter, a displacement stage (not shown), a CCD camera, a dispersion element (e.g., a diffraction grating or prism), and a spectral detector (e.g., a CCD array spectrometer), and its measurement method is as follows. 1. After passing through a beam splitter and objective lens, the line light source irradiates the sample (for example, a wafer, which may be a wafer without a film layer or a wafer with a film layer) to form a linear collection spot on the surface of the sample. As shown in Figure 2A, the incident light provided by the line light source is, for example, broadband incident light in the wavelength range of 193 nm to 1700 nm. 2. Light reflected from the wafer surface and light that enters the wafer and is reflected again at the interface form interference light and return to the beam splitter. This light then passes through a reflection slit and reaches the dispersion element. The light reflected from the reflection slit is then reflected by a plane mirror and reaches the CCD camera, allowing the CCD camera to observe the surface of the sample. 3. The bichromatic light is decomposed by a dispersive element into beams of light with different reflection angles for each wavelength, and after being reflected by a plane mirror, it reaches a spectral detector (e.g., a CCD array spectrometer). 4. The CCD array spectrometer collects R(λ)-λ spectra from multiple sampling points on a collection line on the wafer surface and receives a coherent spectrum at the combined wavelength of the multiple sampling points at the spatial resolution of the CCD array spectrometer. As shown in Figure 2B, where R is reflectance, λ is wavelength, the spectral axis is the wavelength of the bichromatic light, the spatial axis is the spatial position of the sampling point, the reflectance R(λ) has a positive correlation with the collected light intensity, and the density or spacing of the sampling points is determined by the spatial resolution of the CCD array spectrometer. 5. When the spectral measurement system is used to measure the thickness of a sample, the spectrum detected by the CCD array spectrometer is fitted to a spectral database (theoretical spectrum or known spectrum) to obtain the material dispersion coefficient (n(λ), k(λ)). Then, the thickness at the sample sampling point is obtained by a reference table or model matching. This thickness may be the absolute thickness of a wafer without a film layer, or the film thickness of a wafer with a film layer. Here, n is the refractive index of the medium, k is the extinction coefficient, the theoretical spectrum is obtained by spectral modeling, and the known spectrum is obtained by measuring the spectrum of a sample with a known thickness.

[0003] To acquire high-density sampling data and ensure measurement accuracy, spectral measurement systems have high requirements for the spatial resolution of the detector. If the spatial resolution of the detector is limited, spectral information may be lost at certain locations in the area where the light source illuminates the sample surface, which will limit both the spatial resolution of the measured spectrum and the sample thickness. [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention provides a spectral measurement system and a spectral thickness measurement system to address the technical problems present in the prior art. [Means for solving the problem]

[0005] According to a first aspect of the present invention, a spectral measurement system is provided, comprising a light source module, a dispersive element, a detector, a displacement stage controller, and a displacement stage for positioning a sample, wherein the light source module includes a line light source or a surface light source.

[0006] The light source module provides incident light, which irradiates a first region on the sample and generates first interference light after reflection at different interfaces, and the first interference light is incident on the detector via the dispersion element to generate a first coherent spectrum.

[0007] The displacement stage controller controls the displacement stage to move the sample so that the incident light irradiates a second region on the sample, reflects off different interfaces, and generates a second interference light. The second region and the first region partially overlap, and the second interference light enters the detector via the dispersion element to generate a second coherent spectrum.

[0008] The spatial resolution of the detector is improved by compensating the first coherent spectrum based on the second coherent spectrum and obtaining the compensated first coherent spectrum.

[0009] The spectral measurement system provided by the present invention is obtained by moving the position of the sample using a displacement stage, compensating for spectral information on the sample that is lost due to the limitations of the detector's spatial resolution, and further measuring a high spatial resolution spectrum in a first region on the sample.

[0010] According to a second aspect of the present invention, a spectral thickness measurement system is provided which includes the spectral measurement system, wherein the spectral measurement system obtains the thickness of the first region based on a spectral database and the compensated first coherent spectrum.

[0011] The spectral thickness measurement system provided by the present invention moves the position of the sample by a displacement stage, compensates for the spectral information on the sample missing due to the limitation of the spatial resolution of the detector, and further measures the high-spatial-resolution thickness in the first region on the sample.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic diagram of the system structure of a conventional spectral measurement system. [Figure 2A] It is a schematic diagram of signal collection of a conventional spectral measurement system. [Figure 2B] It is a schematic diagram of the spectrum collected by a conventional spectral measurement system. [Figure 3] It is a schematic diagram of the structure of the spectral measurement system provided by one embodiment of the present invention. [Figure 4] It is a schematic diagram of the moving scanning method of the displacement stage. [Figure 5A] It is a schematic diagram of the spectral measurement system including a reflective diffraction grating provided by one embodiment of the present invention. [Figure 5B] It is a schematic diagram of the spectral measurement system including a transmissive diffraction grating provided by one embodiment of the present invention. [Figure 6] It is a schematic diagram of the position comparison of the pixel positions on the sample surface after the displacement stage moves. [Figure 7] It is a schematic diagram of two adjacent light sources among a plurality of light sources. [Figure 8] It is a schematic diagram of the structure of the spectral measurement system provided by one embodiment of the present invention. [Figure 9] It is a schematic diagram of the structure of the spectral measurement system provided by one embodiment of the present invention. [Figure 10] It is a schematic diagram of the structure of the spectral measurement system provided by one embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] To further clarify the objectives, technical means, and advantages of the embodiments of the present invention, the following describes the technical means in the embodiments of the present invention clearly and completely, in conjunction with the drawings of the embodiments. Clearly, the embodiments described are some embodiments of the present invention, not all embodiments. All other embodiments obtained by a person skilled in the art without creative work based on the embodiments of the present invention are all within the scope of protection of the present invention. Furthermore, the technical features in each embodiment or single embodiment provided by the present invention can be combined with one another as arbitrarily as possible so as to form a viable technical means. Such combinations are not limited to the order of steps and / or structural configuration modes, but must be based on what a person skilled in the art can achieve. If a combination of technical means is inconsistent or unrealistic, it should be considered that such a combination of technical means does not exist and is not within the scope of protection claimed by the present invention.

[0014] Figure 3 shows a spectral measurement system provided by one embodiment of the present invention, which generally does not require the addition of optical elements in conventional spectral measurement systems, and compensates for the spatial resolution of the detector by slightly moving the sample position using a displacement stage. High spatial resolution spectra can be obtained even when using a low spatial resolution detector, but high spatial resolution spectra can also be obtained by using a high spatial resolution detector.

[0015] In this embodiment, a high spatial resolution detector is a detector whose spatial resolution satisfies the spectral measurement resolution required by the spectral measurement system; that is, a detector whose spatial resolution is less than or equal to the required spectral measurement resolution is a high spatial resolution detector. A low spatial resolution detector is a detector whose spatial resolution does not satisfy the spectral measurement resolution required by the spectral measurement system; that is, a detector whose spatial resolution is greater than the required spectral measurement resolution is a low spatial resolution detector. For example, if the required spectral measurement resolution is 1 μm, a detector whose spatial resolution is less than or equal to this value is a high spatial resolution detector, and a detector whose spatial resolution is greater than this value is a low spatial resolution detector.

[0016] In some embodiments, using a high spatial resolution detector is costly, so a low spatial resolution detector is used. With a low spatial resolution detector, if spectral information is lost due to the detector's low spatial resolution, the spatial resolution of the measured sample thickness is low. That is, the detector cannot obtain thickness information for a sufficient number of points on the sample because the sampling points on the sample are sparse. The spectral measurement system provided by embodiments of the present invention can improve the spatial resolution of spectral measurements that can be achieved with conventional detectors. Therefore, it becomes possible to use a low-resolution spatial detector, and cost reduction can be achieved.

[0017] In some embodiments, as shown in Figure 3, the spectral measurement system mainly comprises a light source module, a dispersion element (e.g., a diffraction grating or prism), a detector, a displacement stage controller (not shown), and a displacement stage (not shown) for placing a sample, wherein the light source module includes a line light source or a surface light source.

[0018] Here, the light source module provides incident light, which irradiates a first region on the sample and generates a first interference light after reflection at different interfaces, and the first interference light is incident on the detector via the dispersion element to generate a first coherent spectrum; the displacement stage controller moves the sample by controlling the displacement stage so that the incident light irradiates a second region (also called a compensation region) on the sample and generates a second interference light after reflection at different interfaces, the second region partially overlapping with the first region, and the second interference light is incident on the detector via the dispersion element to generate a second coherent spectrum; the spatial resolution of the detector and the spatial resolution of the first coherent spectrum of the first region can be improved by compensating the first coherent spectrum based on the second coherent spectrum and obtaining the compensated first coherent spectrum as the spectrum of the first region.

[0019] Referring to Figure 3 in some embodiments, the spectral measurement system in Figure 3 further includes a beam splitter, and a light source module (e.g., including a line light source) irradiates the sample after passing through the beam splitter and objective lens, the sample being, for example, a wafer, which may be a wafer without a film layer or a wafer with a film layer. The displacement stage moves to an initial acquisition position, or the initial position of the displacement stage is set as the initial acquisition position. The initial acquisition position is the position of the displacement stage and corresponds to a position on the sample. The initial acquisition position is set by the user, and the displacement stage controller controls the displacement stage based on the initial acquisition position. The light source module irradiates a first region on the sample by the beam splitter, and the light reflected from the sample surface and the light reflected after entering the sample form a first interference light which returns to the beam splitter and then reaches the dispersion element. The first interference light is bichromatic light (light including composite wavelengths). The dispersive element decomposes the bichromatic light into beams with different reflection angles for each wavelength, and after being reflected by a plane mirror, it reaches the detector, which detects the first coherent spectrum in the first region on the sample. The sample is moved by a displacement stage, and based on the collection position after the movement, the detector again detects the second coherent spectrum and compensates for the first coherent spectrum based on the second coherent spectrum.

[0020] In one embodiment, the second coherent spectrum is used to compensate for the spectrum of the first region where the measurement was missing in the first coherent spectrum, and the remaining portion of the second coherent spectrum is discarded to obtain the compensated first coherent spectrum.

[0021] Exemplary examples include compensating the first coherent spectrum based on the second coherent spectrum, as follows: The spectral measurement system traverses adjacent sampling points on each pair of samples corresponding to the first coherent spectrum, determines whether a compensation gap exists between adjacent sampling points, and in response to the presence of the compensation gap, searches the second coherent spectrum for the spectrum corresponding to the compensation gap based on the location of the compensation gap, and compensates the first coherent spectrum with the searched spectrum.

[0022] In some embodiments, each collected coherent spectrum can be found in Figure 2B, and each coherent spectrum is a three-dimensional spectrum represented by a reflectance axis, wavelength axis, and spatial axis. Here, there are multiple discrete sampling points in the irradiation area on the sample of the light source, and the detector includes a pixel array composed of multiple pixels, and the spectral signal at each sampling point is characterized by the collection of one pixel on the detector. As shown in Figure 2B, these sampling points are distributed along the spatial axis, the direction of which is, for example, the x-direction in this embodiment, and each sampling point corresponds to the reflectance and wavelength collected by the corresponding pixel. Exemplarily, if a compensation gap exists between adjacent sampling points in the first coherent spectrum, a sampling point with the same coordinates is searched for in the second coherent spectrum based on the coordinates of the compensation gap, and if found, the spectrum of that sampling point in the second coherent spectrum is added to the first coherent spectrum, thereby achieving spectral compensation.

[0023] In one embodiment, determining whether a compensation gap exists between adjacent sampling points includes the following: The adjacent pixels on the detector corresponding to the adjacent sampling points are acquired, and the pixel interval d between the adjacent pixels is obtained. d and the width of a single pixel w d Based on the comparison with the pixel interval d, it is determined whether or not a compensation gap exists between adjacent sampling points. dis the distance between the centers of two adjacent pixels, and the pixel pitch d d is the width w of a single pixel d If it is larger than, there is a compensation gap between adjacent sampling points, and the size of each pixel of the detector is the same.

[0024] Referring to FIG. 6, in another embodiment, determining whether there is a compensation gap between adjacent sampling points includes the following. Obtain the magnification between the pixel of the detector and the sampling point on the sample, and the width w of a single pixel d and obtain the region width w on the sample of a single sampling point corresponding to a single pixel according to the magnification, and the pixel pitch d d and obtain the sampling interval d on the sample corresponding to adjacent sampling points based on the magnification, and determine whether there is a compensation gap between adjacent sampling points based on the comparison between the sampling interval d and the region width w, and the pixel pitch d d is the distance between the centers of two adjacent pixels, the sampling interval d is the distance between the centers of two adjacent sampling points, and if the sampling interval d is larger than the region width w, there is a compensation gap between adjacent sampling points, and the size of each pixel of the detector is the same.

[0025] Here, the magnification is obtained based on the pixel distribution of the detector and the distribution of the sampling points on the sample. Exemplarily, a sampling length L w which is a preset value can be set for the sample, and the detection length L w corresponding to the sampling length L in the detector d is obtained, and the measured value of the magnification is L w / L d . As can be seen from this, the region width w on the sample of a single sampling point = L w / L d ×w d and the sampling interval d = L w / Ld ×d d That is the case.

[0026] Referring to Figure 3, the spectral measurement mechanism can be understood as follows. 1. The beam light source passes through a beam splitter and objective lens before irradiating the sample. 2. Light reflected from the sample surface and light reflected after entering the sample form interference light and return to the beam splitter, where it passes through a reflection slit and reaches the dispersion element. The light reflected from the reflection slit is then reflected by a plane mirror and reaches the CCD camera, allowing the CCD camera to observe the surface of the sample, such as a wafer. 3. The bichromatic light is decomposed into beams with different reflection angles for each wavelength by a dispersing element, and after being reflected by a plane mirror, it reaches the detector. 4. Each of the multiple pixels on the detector corresponds to the R(λ)-λ spectrum collected at each collection point on the irradiation line of the line light source to the sample surface. This is obtained by receiving the coherent spectrum at the composite wavelength of each point on the sample of the line light source at the spatial resolution of the detector. For example, the first coherent spectrum of the first region is obtained, where R is the reflectance and λ is the wavelength. 5. After the displacement stage moves a small distance, steps 2 to 4 above are repeated to perform the measurement, and the coherent spectrum is detected again by the detector to obtain, for example, a second coherent spectrum of the second region. 6. After moving the displacement stage according to its positional order on the sample, the coherent spectrum measured afterward (e.g., the second coherent spectrum) is used to compensate for the coherent spectrum measured before moving the displacement stage (e.g., the first coherent spectrum), and then the compensated spectrum is obtained.

[0027] In some embodiments, when a spectral measurement system is used to measure the thickness of a sample, i.e., when the spectral measurement system is a spectral thickness measurement system, the compensated spectrum is fitted to a spectral database to obtain the material dispersion coefficient (n(λ), k(λ)). The thickness of the sample (e.g., the absolute thickness of the sample or the film thickness of the sample) is obtained by reference table or model matching. This thickness may be the absolute thickness of a wafer without a film layer, or the film thickness of a wafer with a film layer. Here, n is the refractive index of the medium, k is the extinction coefficient, and the spectral database is a theoretical spectrum obtained by spectral modeling, or a known spectrum obtained by measuring the spectrum of a sample having a known thickness.

[0028] Here, in this embodiment, both the first and second regions are less than or equal to the maximum irradiation area of ​​the light source module. The spectral measurement system is arranged to acquire a target region on the sample, the target region including at least one first region, the displacement stage controller acquires multiple sets of positions of the displacement stage, any one set of the positions including a collection position and a compensation position, a first coherent spectrum is acquired at the collection position, the spectral measurement system acquires the second coherent spectrum based on the detector in response to the displacement stage moving to the compensation position, and acquires the spectrum of the target region based on the first and second coherent spectra of each set.

[0029] In this embodiment, the maximum illumination area is the maximum area that the light source module can cover on the sample. Taking a line light source as an example, the maximum illumination area is a rectangular area, and since the line width of a line light source is generally much smaller than the line length, the rectangular area can also be called a line segment, and the maximum illumination area is, in other words, the maximum measurable line length of the line light source.

[0030] In some embodiments, the detection target area includes a plurality (i.e., at least two) first areas. Since the size of the first areas is not limited, the detection target area can be divided into a plurality of first areas, for example, the detection target area can be divided into two first areas of different sizes.

[0031] In some embodiments, the acquisition position and compensation position refer to the position of the displacement stage in different motion states and are both set by the user, and the displacement stage controller controls the movement of the displacement stage based on the acquisition position and compensation position. The acquisition position is related to the user-set scanning path of the displacement stage, and specifically, the acquisition position corresponds to a first region of the sample. Due to the limited spatial resolution of the detector, the first region includes a plurality of discrete points in the scanning path, and these discrete points are sampling points. In one embodiment, the scanning path of the displacement stage may be a curved scanning path or a linear scanning path, and as shown in Figure 4, the scanning path may be, for example, a meandering scanning path, a helical scanning path, or a linear scanning path.

[0032] In some embodiments, as is well known to those skilled in the art, as shown in Figures 3 and 4, when a displacement stage controller controls the movement of the displacement stage according to a meandering scanning path, the spectral measurement system first completes a linear scan along the x-direction, then the displacement stage moves a certain distance along the y-direction, the spectral measurement system then completes another linear scan in the x-direction, and so on, repeating this process sequentially. As shown in Figure 4, when a displacement stage controller controls the movement of the displacement stage according to a linear scanning path, it first completes a linear scan along the x-direction, then changes the position of the displacement stage, then completes another linear scan in the x-direction, and so on, repeating this process sequentially.

[0033] In some embodiments, the displacement stage controller controls the movement of the displacement stage according to a meandering scanning path, and the displacement stage controller controls the displacement stage to move along the x-direction, and the spectral measurement system performs spectral measurements along the x-direction to achieve spectral compensation for the detector (which also applies to beam spacing compensation below), but does not require spectral measurements in the y-direction.

[0034] Here, each pair of positions includes both the acquisition position and the compensation position, where the acquisition position corresponds to the first region of the sample and the compensation position corresponds to the second region of the sample. From a pair of first and second coherent spectra, the spectrum of the corresponding first region can be obtained.

[0035] For example, the detection area includes two adjacent first areas in the x-direction. The spectrum of one first area is obtained based on one set of first and second coherent spectra, the spectrum of another first area is obtained based on another set of first and second coherent spectra, and the spectrum of the detection area is obtained based on the spectra of both first areas.

[0036] In this embodiment, the description that A executes C in response to B means that A executes C immediately after the completion of B's ​​execution or A executes C after a certain period of time has elapsed. Here, A is the executing entity, B is an action, and C is another action, and the term "execution" may be omitted.

[0037] Here, the type of detector is not limited; it just needs to be able to detect spectral information. For example, a spectral detector is used, specifically a matrix spectrometer or a linear spectrometer. The beam shape of the light source module is not limited; the light source module can include a line source or a surface source. The type of objective lens is not limited; it may have a large or small field of view (FOV).

[0038] In some embodiments, the incidence method of the incident light provided by the light source module is not limited to perpendicular incidence and oblique incidence, but is not limited to these. As shown in Figure 3, a perpendicular incidence spectral measurement system is shown, and as shown in Figures 5A and 5B, oblique incidence spectral measurement systems are shown, respectively. Here, the diffraction grating in Figure 5A is a reflection diffraction grating, and the diffraction grating in Figure 5B is a transmission diffraction grating.

[0039] In one embodiment, referring to Figures 5A and 5B, the measurement method for oblique incidence of a line light source is as follows: the line light source is incident obliquely and focused on the wafer by a columnar lens (not noted) to generate interference light, which is then focused into a collimated line beam by an objective lens (not noted, e.g., a columnar lens), decomposed into monochromatic light with different angles depending on the wavelength via a transmission or reflection diffraction grating, reflected by a plane mirror to reach the detector, and forming a three-dimensional spectrum formed by the reflectance axis-wavelength axis-spatial axis (position on the sample). In one embodiment, the illumination device includes a CCD camera and illumination (i.e., illumination light source), the illuminated beam is incident perpendicularly on the wafer, and the CCD camera is used to collect a surface image of the wafer and to check whether there are defects on the wafer surface or whether the line light source is in focus.

[0040] In one embodiment, the displacement stage controller moves the displacement stage based on a preset number of movements and movement step size to acquire one or more of the second regions, wherein the number of movements and the number of second regions are the same.

[0041] In some embodiments, after a first coherent spectrum corresponding to a first region on the sample irradiated by the light source module is acquired by the detector, a displacement stage controller controls the displacement stage to move the sample's position, thereby acquiring one or more second regions on the sample. Here, the displacement stage controller acquires one second region each time the displacement stage is moved, and the number of moves matches the number of second regions. For each second region, the detector again detects a second coherent spectrum. The first coherent spectrum is compensated using the second coherent spectra detected by the detector one or more times to obtain a compensated first coherent spectrum.

[0042] In one embodiment, when acquiring multiple different second regions that partially overlap with the first region, the first coherent spectrum is compensated based on multiple second coherent spectra corresponding to the multiple second regions, thereby further improving the spatial resolution of the detector.

[0043] As can be understood, when detecting spectral information on a sample, whether the detector has low or high spatial resolution, the spatial resolution of the detector is limited, so there is always a gap between two pixels of the detector and two sampling points on the wafer, resulting in a situation where spectral information is always lost, and further affecting the spatial resolution of the wafer spectral measurement. Therefore, embodiments of the present invention improve the spatial resolution of the detector by changing the relative position between the light source module and the sample by moving the displacement stage, and further compensating for the measured spectrum at the gap between sampling points.

[0044] Taking the example that the light source module includes a line light source, Figure 6 shows the positions on the wafer corresponding to the first collection of spectral information by the detector, i.e., a row of sampling points on the wafer. These sampling points are distributed along the x-direction, forming a first region. After the displacement stage moves by Δx along the x-direction, the detector again collects sampling points from another row of sampling points on the wafer, corresponding to the spectral information. These sampling points are distributed along the x-direction, forming a second region. Here, Figure 6 shows the lateral relative positions corresponding to the two rows of sampling points on the wafer before and after the movement of the displacement stage. For clarity, the shape of the sampling points on the wafer corresponding to the pixels is simplified to a square in the two detector measurements, and the positions on the wafer corresponding to the pixels are displayed vertically separated in the two detector measurements, showing only the lateral relative positions.

[0045] The displacement stage may move using either equally spaced measurements (i.e., the movement step size of the displacement stage in each step is the same) or non-equally spaced measurements (i.e., the movement step size of the displacement stage may differ each time). For example, equally spaced measurements are generally used when it is necessary to measure the spectrum at all locations on the sample. Non-equally spaced measurements are typically used when the focus is on the spectrum of only a specific region on the sample.

[0046] In some embodiments, the number of movements is one or more, the displacement stage controller controls the movement of the displacement stage based on a linear scanning path or a meandering scanning path, the movement step size is nΔx and Δx∈[1 / 2,1]w.

[0047] Here, w is the width of the sampling point region on the sample corresponding to a single pixel of the detector, and n is a positive integer. The direction in which the width is defined is along the distribution direction of the sampling points on the sample corresponding to the pixels of the detector.

[0048] Exemplary, the displacement stage controller controls the movement of the displacement stage based on a linear or meandering scanning path, and in the case of equally spaced measurements, the optimal number of movement steps of the displacement stage is INT(d / w-1) (i.e., the integer part of (d / w-1)), the recommended movement step size is (1 / 2)×w, the actual movement step size and number are not limited, and d is the sampling interval between two sampling points on the sample corresponding to two adjacent pixels of the detector. In one embodiment, it is not recommended to set Δx < (1 / 2)×w, because in this case the detector will oversample, resulting in an excessive number of measurements leading to unnecessary measurement time, while an insufficient number of measurements will not achieve the required spectral measurement accuracy.

[0049] Herein, as an embodiment, the light source module includes a light source controller and a plurality of light sources, the plurality of light sources arranged along a first direction, and a beam gap exists between at least one pair of adjacent light sources adjacent along the first direction, thereby creating a beam gap region in the sample, the light source controller controls the on or off of each light source, the displacement stage controller controls the displacement stage to move along the first direction based on a linear scanning path or a meandering scanning path, and acquires a third coherent spectrum to compensate for the beam gap region based on the detector and the operating light sources (similarly, the first region and the third region on the sample corresponding to the third coherent spectrum partially overlap). The spectrum of the first region is acquired by compensating the first coherent spectrum based on the second and third coherent spectra.

[0050] In this embodiment, the first direction is a linear direction, and the word "arrangement" may be a row or a column. Exemplarily, multiple light sources form a column along the first direction, as shown in Figures 7 and 8, where multiple light sources form a column (i.e., a row) along the x direction, and the first direction is the x direction. Alternatively, multiple light sources may be formed in a column (i.e., a row) along the z direction, and the first direction is the z direction. It should be noted in particular that, although the above description has explained the case in which multiple light sources are arranged along the first direction and form a column, it does not exclude the case in which all light sources form multiple columns, because the number of light sources in a column is less than or equal to the total number of light sources. For example, if the total number of light sources is 8, 4 light sources may form a column along the x direction, and 4 light sources may form another column along the x direction.

[0051] As can be understood, by using multiple light sources that can be individually switched on / off as incident light sources for the spectral measurement system in Figure 3, the maximum irradiation area in a single measurement can be increased, and, taking line light sources as an example, the maximum measurement line length during a single measurement can be increased, further improving the measurement efficiency (see Figure 7). Since there is a beam gap between each adjacent line light source, when spectral information is detected by the detector, there is a beam gap region in the sample, and the beam gap region is an undetected region. Accordingly, embodiments of the present invention provide a spectral measurement system based on multiple light sources, and multiple line light sources arranged in a line and the number of light sources is the same as the total number of light sources are described as an example (see Figure 8).

[0052] In one embodiment, a physical gap exists between two adjacent light sources. In one embodiment, the housings of two adjacent light sources may come into contact with each other, i.e., the possibility of two adjacent light sources coming into contact is not ruled out because light sources generally have housings, and even if the housings of two adjacent light sources come into contact, a beam gap exists between the two adjacent light sources due to the wall thickness of the housings.

[0053] In Figures 7 and 8, when there is a beam gap between each line source, there is a gap in the single detection process of the detector, and the beam gap region on the sample cannot be detected. The spatial resolution of the detector can be compensated by using a displacement stage movement method, and at the same time, the spectrum corresponding to the beam gap can be compensated. L is the total length of the single line source, D is the beam gap between adjacent line sources, and the square is a simplified shape of the sampling point on the wafer corresponding to the detector pixel.

[0054] In this case, when compensating for the spectrum corresponding to the beam spacing of the line light source, the light source controller controls the operation of all light sources to acquire a first coherent spectrum based on the detector, the light source controller turns off some of the light sources in response to the detector acquiring the first coherent spectrum, and the displacement stage controller controls the movement of the displacement stage in response to the light source controller turning off some of the light sources and acquires a third coherent spectrum based on the detector.

[0055] Referring to Figure 8, the spectral measurement system includes a row of light sources that can be individually switched on / off, a beam splitter, a dispersive element, a detector (e.g., a CCD array spectrometer), and a displacement stage on which the sample is placed.

[0056] In some embodiments, the displacement stage moves to an initial collection position, or the initial collection position is the initial position of the displacement stage. All light sources in a row are turned on, and all light sources illuminate the sample with the beam splitter, and the light reflected from the sample surface and the light reflected after entering the sample form interference light which returns to the beam splitter and then reaches the dispersion element. The dispersion element decomposes the interference light into beams with different reflection angles for each wavelength, reflects them by mirrors and reaches the detector, which detects a first coherent spectrum. Some of the light sources are turned off and moved by the displacement stage, and based on the position after the move, the detector again detects a third coherent spectrum to compensate for the spectrum of the beam-spacing region on the sample corresponding to the beam spacing.

[0057] Here, the light source controller turns off one of the multiple light sources at an edge in response to the detector acquiring a first coherent spectrum. In one embodiment, if the size of each light source is the same and the beam spacing D is less than or equal to the length L in the beam spacing direction of a single light source, the displacement stage moves once to acquire the third coherent spectrum. If the beam spacing D is greater than the length L, the displacement stage moves multiple times, acquiring the third coherent spectrum once after each movement.

[0058] As can be understood, the third coherent spectrum is acquired by the detector by controlling the displacement stage to move the sample and turning off some of the light sources among all of them. By turning off one of the edge light sources among all of them, for example, the first or last light source arranged sequentially along the first direction, and determining the number of times the displacement stage is moved based on the relationship between the beam spacing D and the length L in the beam spacing direction of a single light source, for example, one acquisition of the third coherent spectrum for each time the displacement stage is moved.

[0059] After acquiring the third coherent spectrum, the light source controller selects and operates an arbitrary light source in response to the detector acquiring the third coherent spectrum, and the displacement stage controller controls the movement of the displacement stage and acquires the second coherent spectrum based on the detector in response to the light source controller selecting and operating an arbitrary light source.

[0060] As can be understood, the third coherent spectrum compensates for the missing beam-spacing region spectrum in the first coherent spectrum, and the second coherent spectrum further compensates for the first coherent spectrum. If the spectral measurement system is a spectral thickness measurement system, the thickness of the sample in the first region is obtained based on the first coherent spectrum compensated by the third and second coherent spectra and the spectral database.

[0061] For example, the beam spacing between adjacent light sources is compensated by moving the displacement stage, and then the spatial resolution of the detector is compensated by moving the displacement stage.

[0062] The specific measurement process is as follows: First, all line light sources in a row are turned on, and the detector detects the first coherent spectrum. At this time, there is a gap in the first coherent spectrum detected by the detector because there is a beam gap between adjacent light sources. Therefore, one of the light sources is then turned off. The optimal method is to turn off either the first or last light source and move the displacement stage. The direction of movement of the displacement stage is the first direction (e.g., the x-direction) and it moves in the direction of the turned-off light source. For example, as with the two line light sources in Figure 8, if the first light source on the left is turned off, the displacement stage moves to the left. If the second light source from the right is turned off, the displacement stage moves to the right, and the detector detects and obtains the third coherent spectrum again. Here, the third coherent spectrum can compensate for the spectrum that was missing from the first coherent spectrum due to the beam gap.

[0063] The above movement of the displacement stage compensates only the spectrum in the beam spacing region corresponding to the beam spacing, and can further compensate for the spatial resolution of the detector. In one embodiment, when the spatial resolution of the detector is compensated by moving the displacement stage, only a single line light source is turned on, or any one of all light sources may be used. The step size and number of movements of the displacement stage have already been described in the above embodiment, and the measurement mechanism when compensating for the spatial resolution of the detector has also been described, so redundant explanations will be omitted here.

[0064] In one embodiment, spectral compensation is achieved by using a third coherent spectrum to compensate for the spectrum in the first region that was missing from the measurement by the first coherent spectrum, and discarding the remaining portion of the third coherent spectrum.

[0065] As can be seen from the analysis above, when multiple light sources are installed, there is a beam gap between at least one pair of adjacent light sources, and as a result, a beam gap region exists in the sample.

[0066] Exemplary examples include compensating the first coherent spectrum based on the third coherent spectrum, as follows: The spectrum measurement system searches for a spectrum corresponding to the beam spacing region from the third coherent spectrum according to the position of the beam spacing region, and compensates the first coherent spectrum with the searched spectrum. Here, the spatial distribution and size of multiple light sources are known information, which allows us to obtain the position of the beam spacing between adjacent light sources. Furthermore, by matching the positional transformation relationship of the irradiation area corresponding to the multiple light sources and the sample, we can determine the position of the beam spacing region on the sample that corresponds to the beam spacing.

[0067] In one embodiment, the detector performs three detections, the third coherent spectrum compensates for the spectrum missing from the first coherent spectrum due to the beam spacing, and the second coherent spectrum compensates for the spectrum missing from the first coherent spectrum due to the spatial resolution limit. If the spectral measurement system is a spectral thickness measurement system, fitting is performed based on the compensated first coherent spectrum and spectral database to obtain the material dispersion coefficient (n(λ), k(λ)), and then the sample thickness is obtained by reference table or model matching.

[0068] As an example, based on the spectral measurement system in Figure 8, the measurement method is described as follows: 1. The multi-probe beam light source passes through a beam splitter and objective lens before being irradiated onto the sample. 2. Light reflected from the sample surface and light reflected after entering the sample form interference light and return to the beam splitter, then pass through a reflection slit to reach the dispersion element. The light reflected from the reflection slit is then reflected by a plane mirror and reaches the CCD camera, allowing the CCD camera to observe the surface of the sample, such as a wafer. 3. The dispersive element decomposes composite wavelength light into beams with different reflection angles, which are then reflected by a plane mirror and reach the detector. 4. The detector collects the R(λ)-λ spectrum at each point on the measurement line and receives and acquires the coherent spectrum at the composite wavelength of each point on the measurement line at the detector's spatial resolution, i.e., the first coherent spectrum is obtained. 5. After the displacement stage moves a certain distance, steps 1-4 are repeated to complete measurements to compensate for the spectrum in the beam spacing region, thereby obtaining a third coherent spectrum. 6. Using a single line light source, the displacement stage returns to the measurement start point in step 1, then moves a distance Δx in the direction of the line light source (i.e., the direction in which spatial resolution needs to be compensated; if it is a surface light source, it moves along the direction in which resolution needs to be compensated), and then steps 1-4 are repeated to obtain a second coherent spectrum to compensate the spatial resolution of the detector. n is a positive integer, where the purpose of moving the distance is for the light spot to compensate for the beam spacing D. For example, first move L distance, and if the beam spacing D cannot be compensated in one move of L distance, move L distance again and continue until it can be compensated. 7. The first coherent spectrum is compensated using the second and third coherent spectra to obtain the compensated first coherent spectrum.

[0069] In some embodiments, when a spectral measurement system is used to measure the thickness of a sample, i.e., when the spectral measurement system is a spectral thickness measurement system, the compensated first coherent spectrum is fitted to a spectral database to obtain the material dispersion coefficient (n(λ), k(λ)), and then the sample thickness is obtained by a reference table or model matching.

[0070] In this embodiment, since the total length of the multiple line light sources is larger, it is necessary to use optical components whose size is compatible with the multiple light sources, such as longer beam splitters and dispersion elements. The movement method of the displacement stage compensates for the spatial resolution of the detector and the beam spacing of the light sources, enabling the measurement of spectra with high spatial resolution.

[0071] In one embodiment, the detector includes a spectral detector. Alternatively, the detector includes a light intensity detector, and the spectral measurement system further includes a wavelength controller and a wavelength modulator, wherein the wavelength controller is configured to change the output wavelength of the wavelength modulator, and the light intensity detector detects light intensities corresponding to different output wavelengths, thereby forming a discrete spectrum based on the output wavelength and light intensity.

[0072] Here, Figures 9 and 10 show a spectral measurement system in which the detector is a light intensity detector. When the detector is a light intensity detector, the spectral measurement system further includes a wavelength controller and a wavelength modulator, the wavelength modulator being used to modulate the output wavelength. The spectral measurement method is similar to the spectral measurement method when the detector is a spectral detector, and specifically includes the following: The displacement stage controller controls the displacement stage to move it to the initial collection position, or sets the initial position of the displacement stage as the initial collection position. The light source module irradiates the sample via the beam splitter, and the light reflected from the sample surface and the light reflected after entering the sample form interference light which returns to the beam splitter and reaches the wavelength modulator. The wavelength controller changes the output wavelength of the wavelength modulator, causing it to output quasi-monochromatic light (i.e., close to monochromatic light) of different wavelengths, which reach the dispersive element, forming monochromatic light of each wavelength which reaches the light intensity detector, and the light intensity detector detects the first coherent spectrum. The displacement stage moves the sample position, and based on the collection position after the move, the detector again detects the second coherent spectrum, where the second coherent spectrum compensates for the first coherent spectrum and improves the spatial resolution of the light intensity detector. Other details refer to the previous embodiment, and redundant explanations are omitted here.

[0073] As can be seen, referring to Figure 9, in the stage movement configuration shown in Figure 3, cost reduction is possible by using an intensity detector instead of a spectral detector. The advantage in this case is that subsequent processing can be simplified by using specific discrete wavelengths, i.e., only characteristic spectral lines need to be observed. As shown in Figure 9, the wavelength modulator includes, but is not limited to, monochromators, filters, multifilters, and spatial light modulators. The position of the wavelength modulator is not limited and may be at any position from the light source module to the detector. The slit after the dispersive element is selective and can be added, removed, or adjusted depending on the situation. In Figure 9, the wavelength modulator is located before the dispersive element, and in Figure 10, the wavelength modulator is located after the light source module.

[0074] As an example, using Figure 9 as an example, the measurement method is explained as follows. 1. The beam light source passes through a beam splitter and objective lens before being irradiated onto the sample. 2. The resulting interference light passes through the beam splitter and reflection slit to reach the wavelength modulator, where it allows only linear light of a specific wavelength to pass through. 3. The linear light generates monochromatic light after passing through a dispersive element, and after passing through a slit, the wavelength is further filtered and reflected by a plane mirror before reaching the light intensity detector. 4. The detector collects the R(λ)-λ spectrum at each point on the line and obtains the coherent spectrum at the combined wavelength of each point on the measurement line at the detector's spatial resolution. Here, when multi-wavelength light passes through the wavelength modulator, almost only light of a single wavelength passes through. The wavelength range of this light ray is further reduced after passing through the rotatable dispersion element and slit to obtain monochromatic light, which is a single-wavelength ray. It is reflected by a rotatable plane mirror and reaches the detection surface of the light intensity detector, obtaining the light intensity distribution at a single wavelength of the line source, which contains sample (e.g., wafer) information. At this time, the position of the hardware and displacement stage does not move, and the wavelengths that can pass through the wavelength modulator are adjusted so that other wavelengths reach the rotatable dispersion element and slit, and finally reach the detector to complete the measurement at that wavelength. After repeatedly adjusting the wavelength, a coherent spectrum of composite wavelengths at the measurement position can be obtained. 5. After moving the displacement stage by a small distance, repeat the above steps to perform the measurement. Here, the method of moving the displacement stage is the same as the method of moving the spectral detector. 6. After moving the displacement stage according to its positional order on the sample, the measured coherent spectrum (e.g., the second coherent spectrum) is used to compensate for the spectrum measured before the displacement stage moved (e.g., the first coherent spectrum), and then the compensated spectrum is obtained.

[0075] In some embodiments, when a spectral measurement system is used to measure the thickness of a sample, i.e., when the spectral measurement system is a spectral thickness measurement system, the compensated spectrum is fitted to a spectral database to obtain the material dispersion coefficient (n(λ), k(λ)), and then the thickness of the sample is obtained by a reference table or model matching.

[0076] Here, the type of detector is not limited; it just needs to be able to detect the light intensity information of a ray. If the detection surface of the detector is point-shaped, the plane mirror is rotated along the length of the line light source so that each point on the line light source at that wavelength passes through the detector in sequence, and thereby the point-shaped detector can still obtain light intensity information for any point on the line.

[0077] The spectral measurement system provided by embodiments of the present invention has the following advantages. (1) There is no need to add extra optical elements, and the spatial resolution of the detector is compensated by minute movements of the displacement stage. (2) When multiple light sources are formed in a line, the beam spacing region on the sample corresponding to the beam spacing between light sources is compensated by moving the displacement stage. (3) This method is applicable not only to spectral detectors but also to light intensity detectors. When using a light intensity detector, it is necessary to add a wavelength controller and a wavelength modulator, and a slit can be selectively added.

[0078] In embodiments of the present invention, a spectral thickness measurement system is provided which further includes a spectral measurement system to obtain a thickness associated with a sample based on spectral measurement of the sample, wherein the thickness may be the film thickness on the sample or the absolute thickness of the sample. As described above, when the spectral measurement system is used to measure the thickness of a sample, the spectral measurement system is a spectral thickness measurement system which obtains the thickness of the first region based on a spectral database and the compensated first coherent spectrum, wherein the spectral database may be a theoretical spectrum or a known spectrum.

[0079] In this embodiment, the term "absolute thickness" is used to distinguish it from the term "film thickness." For a sample without a film layer, the absolute thickness of the sample is the thickness of the sample. For a sample with a film layer, the sample includes a substrate and the film layer, and the absolute thickness of the sample may be the thickness of the substrate, or the sum of the thickness of the substrate and the thickness of the film layer. A spectral thickness measurement system can measure the film thickness of the film layer and / or the thickness of the substrate.

[0080] For example, when a spectral thickness measurement system is used to measure the film thickness of a sample, the spectral thickness measurement system is, for example, a spectral reflectance film thickness gauge as shown in Figure 3, in which the light reflected from the upper surface of the film layer and the light reflected from the lower surface of the film layer after the incident light has entered the film layer form interference light.

[0081] Exemplary, spectral thickness measurement systems are used to measure the absolute thickness of a sample. Taking a wafer as an example, as is well known to those skilled in the art, silicon wafers have good transparency to light in the wavelength range of about 1000 nm to about 6000 nm, and therefore the absolute thickness of a silicon wafer can be measured by selecting a light source in an appropriate wavelength range. In one embodiment, the light source is selected to be in the near-infrared wavelength range of 780 nm to 2526 nm. In another embodiment, the light source is selected to be in the near-infrared band of 1000 nm to 1700 nm.

[0082] For example, when a spectral thickness measurement system is used to measure the absolute thickness of a sample, the spectral thickness measurement system is, for example, the spectral reflectance absolute thickness measuring instrument shown in Figure 3.

[0083] Taking a wafer without a film layer as an example, the light reflected from the upper surface of the wafer and the light reflected from the lower surface of the wafer after it enters the wafer form interference light, and the absolute thickness of the wafer can be obtained by interference light processing.

[0084] Taking a wafer having a film layer as an example, the light reflected from the upper surface of the film layer and the light reflected from the lower surface of the film layer after the incident light enters the film layer form interference, and the light reflected from the upper surface of the substrate and the light reflected from the lower surface of the substrate after the incident light enters the substrate also form interference. The detector collects the interference light and processes it to obtain the film thickness of the film layer and the absolute thickness of the substrate. Here, the wafer includes a substrate and a film layer located on the substrate.

[0085] Since the spectral thickness measurement system includes the spectral measurement system in the above embodiment, when the spectral measurement system acquires a high spatial resolution spectrum of a first region on the sample, the spectral thickness measurement system acquires a high spatial resolution thickness of the first region on the sample.

[0086] In the above embodiments, each embodiment is described with particular emphasis, and for parts not described in detail in one embodiment, you can refer to the relevant descriptions of other embodiments.

[0087] While preferred embodiments of the present invention have been described, those skilled in the art, upon understanding the basic creative concepts, will be able to make further changes and modifications to these embodiments. Therefore, the scope of the appended claims is intended to be construed as encompassing the preferred embodiments, as well as all changes and modifications that fall within the scope of the present invention.

[0088] Clearly, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to include such modifications and variations, provided that they fall within the scope of the claims of the present invention and the equivalent art.

Claims

1. The light source module includes a dispersive element, a detector, a displacement stage controller, and a displacement stage for positioning a sample, wherein the light source module includes a line light source or a surface light source. The light source module provides incident light, which irradiates a first region on the sample and generates first interference light after reflection at different interfaces, and the first interference light is incident on the detector via the dispersion element to generate a first coherent spectrum. The displacement stage controller controls the displacement stage to move the sample such that the incident light irradiates a second region on the sample, reflects off different interfaces, and generates a second interference light, the second region and the first region partially overlap, and the second interference light is incident on the detector via the dispersion element to generate a second coherent spectrum. A spectral measurement system characterized by improving the spatial resolution of the detector by compensating the first coherent spectrum based on the second coherent spectrum and obtaining the compensated first coherent spectrum.

2. The spectral measurement system according to claim 1, characterized in that both the first region and the second region are less than or equal to the maximum irradiation area of ​​the light source module.

3. The spectral measurement system according to claim 1, characterized in that the displacement stage controller moves the displacement stage based on a preset number of movements and movement step size to acquire one or more of the second regions, wherein the number of movements and the number of second regions are the same.

4. The spectral measurement system according to claim 3, wherein the displacement stage controller controls the movement of the displacement stage according to a linear scanning path or a meandering scanning path, the movement step size is nΔx and Δx ∈ [1 / 2, 1]w, where w is the width of the region on the sample corresponding to a single pixel of the detector, and n is a positive integer.

5. The light source module includes a light source controller and a plurality of light sources, the plurality of light sources are arranged along a first direction, and there is a beam gap between at least one pair of adjacent light sources such that a beam gap region exists on the sample. The spectrum measurement system according to claim 1, characterized in that the light source controller controls the on / off status of each light source, the displacement stage controller controls the movement of the displacement stage along the first direction according to a linear scanning path or a meandering scanning path to acquire a third coherent spectrum for compensating the beam spacing region based on the detector and the operating light sources, and the first coherent spectrum is compensated based on the second and third coherent spectra to acquire the spectrum of the first region.

6. The light source controller controls the operation of all light sources and acquires a first coherent spectrum based on the detector. The light source controller, in response to the detector acquiring the first coherent spectrum, turns off a portion of the light source. The spectral measurement system according to claim 5, characterized in that the displacement stage controller controls the movement of the displacement stage in response to the light source controller turning off a portion of the light source, and acquires the third coherent spectrum based on the detector.

7. The light source controller, in response to the detector acquiring the third coherent spectrum, selects and activates one of the light sources. The displacement stage controller controls the movement of the displacement stage in response to the light source controller selecting and activating one of the light sources, and acquires the second coherent spectrum based on the detector. In response to the detector acquiring the first coherent spectrum, the light source controller turns off one of the multiple light sources, specifically an edge light source. Each light source is the same size. If the beam spacing D is less than or equal to the length L in the beam spacing direction of a single light source, the displacement stage moves once to acquire the third coherent spectrum. The spectrum measurement system according to claim 6, characterized in that when the beam spacing D is greater than the length L, the displacement stage moves multiple times, and the third coherent spectrum is acquired once after each movement.

8. Compensating the first coherent spectrum based on the third coherent spectrum means The spectral measurement system according to claim 5, characterized in that the spectral measurement system includes searching for a spectrum corresponding to the beam spacing region from the third coherent spectrum based on the position of the beam spacing region, and compensating the first coherent spectrum with the searched spectrum.

9. Compensating the first coherent spectrum based on the second coherent spectrum means A spectral measurement system according to any one of claims 1 to 8, characterized in that the spectral measurement system traverses each pair of adjacent sampling points on a sample corresponding to the first coherent spectrum, determines whether a compensation gap exists between the adjacent sampling points, and in response to the presence of the compensation gap, searches the second coherent spectrum for a spectrum corresponding to the compensation gap based on the location of the compensation gap, and compensates the first coherent spectrum with the searched spectrum.

10. Determining whether or not a compensation gap exists between the adjacent sampling points is: This includes obtaining adjacent pixels on the detector corresponding to the adjacent sampling points, determining whether the compensation gap exists between the adjacent sampling points based on a comparison of the pixel spacing between the adjacent pixels and the width of a single pixel, where the pixel spacing is the distance between the centers of the two adjacent pixels, and if the pixel spacing is greater than the width of a single pixel, determining that the compensation gap exists between the adjacent sampling points and that the size of each pixel in the detector is the same, or Alternatively, the spectral measurement system according to claim 9, comprising: obtaining the magnification ratio between the pixels of the detector and the sampling points on the sample; obtaining the region width on the sample of a single sampling point corresponding to the single pixel based on the width of a single pixel and the magnification ratio; obtaining the sampling interval on the sample corresponding to the adjacent sampling points based on the pixel spacing and the magnification ratio; determining whether the compensation gap exists between the adjacent sampling points based on a comparison of the sampling interval and the region width; the pixel spacing being the distance between the centers of two adjacent pixels, the sampling interval being the distance between the centers of two adjacent sampling points, and determining that if the sampling interval is greater than the region width, the compensation gap exists between the adjacent sampling points and the size of each pixel of the detector is the same.

11. A spectral measurement system according to any one of claims 1 to 10, The spectral thickness measurement system is characterized by obtaining the thickness of the first region based on a spectral database and the first coherent spectrum after compensation.

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