Spectrometer, thickness measurement system, thickness calculation device, method for producing spectrometer, and method for calculating thickness
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2026-01-13
- Publication Date
- 2026-05-22
Abstract
Description
Spectrometer, thickness measurement system, thickness calculation device, spectrometer manufacturing method and thickness calculation method
[0001] The present invention relates to a spectrometer, a thickness measurement system, a thickness calculation device, a method for manufacturing a spectrometer, and a thickness calculation method.
[0002] Conventionally, a technique has been proposed for measuring the thickness of a target sample based on the reflectance spectrum of the target sample by irradiating the target sample with light.
[0003] For example, Patent Document 1 (JP 2014-55780 A) discloses the following film thickness measurement method: That is, the film thickness measurement method uses a sample including a reference film having a first wavelength region and a second wavelength region with different light transmittances, the first wavelength region having a lower light transmittance than the second wavelength region, one or more measurement target films formed on one side of the reference film, and one or more measurement target films formed on the other side of the reference film, and measures the thickness of each of the measurement target films, the film thickness measurement method including an irradiation step of irradiating the sample with light from the one side, a measurement step of measuring a reflectance spectrum of the light from the sample in part or all of the first wavelength region and part or all of the second wavelength region, a first calculation step of calculating a thickness of each of the measurement target films formed on the one side based on the reflectance spectrum in the first wavelength region, and a second calculation step of calculating a thickness of each of the films formed on the other side based on the thickness of each of the measurement target films formed on the one side and the reflectance spectrum in at least the second wavelength region.
[0004] Furthermore, for example, Patent Document 2 (JP 2008-286583 A) discloses an optical property measuring device equipped with a Cassegrain-type reflective objective lens. The reflective objective lens includes a convex reflecting mirror and a concave reflecting mirror arranged so that the central axis coincides with the optical axis. In the optical property measuring device described in Patent Document 2, the measurement reflected light generated by reflection from the surface of the object to be measured passes through a pinhole and enters the spectroscopic measurement unit, while the back-reflected light generated by reflection from the back surface of the object to be measured cannot pass through the pinhole. Therefore, the optical property measuring device described in Patent Document 2 can avoid the effects of back-reflected light, i.e., stray light.
[0005] JP 2014-55780 A JP 2008-286583 A
[0006] There is a need for a technique that goes beyond the techniques described in Patent Documents 1 and 2 and that is capable of more accurately measuring the thickness of the surface layer of a target sample having a multilayer structure.
[0007] The present invention has been made to solve the above-mentioned problems, and its object is to provide a spectrometer, a thickness measurement system, a thickness calculation device, a method for manufacturing a spectrometer, and a thickness calculation method that are capable of more accurately measuring the thickness of the surface layer of a target sample with a multilayer structure.
[0008] (1) In order to solve the above problem, a spectrometer according to one aspect of the present invention is a spectrometer used to measure the thickness of a surface layer of a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, and includes a light-receiving unit that receives light irradiated from the surface layer side of the target sample and reflected from the target sample, and a spectroscopic unit that generates a reflected light spectrum by dispersing the reflected light, and the spectroscopic unit generates the reflected light spectrum in a spectroscopic wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the layer consisting of the surface layer and the lower layer is equal to or less than a predetermined upper limit.
[0009] In this way, by setting a lower limit for the round-trip internal transmittance of the surface layer and an upper limit for the round-trip internal transmittance of the layer comprising the surface layer and the lower layer, and generating a reflected light spectrum in a spectral wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than the lower limit and the round-trip internal transmittance of the layer comprising the surface layer and the lower layer is equal to or less than the upper limit, it is possible to generate a reflected light spectrum that includes components of light reflected from the light-irradiated surface of the surface layer and components of light reflected from the interface between the surface layer and the lower layer, while reducing components of light reflected from the interface opposite the interface in the lower layer. Therefore, the thickness of the surface layer can be calculated more accurately based on the reflectance spectrum, which is an interference waveform of the surface layer generated using the reflected light spectrum. Therefore, the thickness of the surface layer of a multilayered target sample can be measured more accurately. Here, the "round-trip internal transmittance I(d)" corresponds to the component of light incident on a layer of thickness d that is reflected at the interface opposite the incident surface, i.e., the back surface, and returns to the incident surface. It represents the attenuation due to material absorption during the round-trip process in the layer as a transmittance.
[0010] (2) In the above (1), the spectroscopic unit may generate the reflected light spectrum in the spectroscopic wavelength range in which, within the thickness range of the surface layer, the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined threshold value, and the round-trip internal transmittance of the layer consisting of the surface layer and the lower layer is equal to or less than the threshold value.
[0011] With this configuration, it is possible to generate a reflected light spectrum that is more effective in thickness measurement, taking into consideration the detection limit based on noise, dynamic range, etc. Specifically, for example, it is possible to generate a reflected light spectrum in which the level of reflected light reflected at the interface between the surface layer and the lower layer is equal to or higher than the noise level, and the level of reflected light reflected at the interface between the lower layer and another lower layer is equal to or lower than the noise level.
[0012] (3) In the above (1) or (2), the surface layer may be a silicon layer, and the spectroscopic unit may generate the reflected light spectrum in the spectroscopic wavelength range of 650 nm or more and 800 nm or less.
[0013] With this configuration, the thickness of the silicon layer that constitutes the main surface of the multi-layer structure can be measured more accurately.
[0014] (4) In order to solve the above problem, a thickness measurement system according to a certain aspect of the present invention includes a spectrometer according to any one of (1) to (3) above, and a macro-optical system that irradiates light from a light source onto the surface layer side of the target sample and guides the reflected light of the irradiated light from the target sample to the spectrometer.
[0015] With this configuration, the thickness of the surface layer can be measured more quickly than with a microspectroscopic film thickness meter such as the optical property measuring device described in Patent Document 2.
[0016] (5) In order to solve the above problem, a thickness calculation device according to a certain aspect of the present invention is a thickness calculation device used to measure the thickness of a surface layer of a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, and includes an acquisition unit that acquires a reflected light spectrum of light that is irradiated from the surface layer side of the target sample and reflected from the target sample, a generation unit that generates a reflectance spectrum of the target sample based on the reflected light spectrum acquired by the acquisition unit, and a calculation unit that calculates the thickness of the surface layer based on the reflectance spectrum generated by the generation unit, wherein the generation unit generates the reflectance spectrum in a wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the layer consisting of the surface layer and the lower layer is equal to or less than a predetermined upper limit.
[0017] In this way, a reflectance spectrum is generated based on the reflected light spectrum of the reflected light from the target sample, in a wavelength range where the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the combined surface layer and lower layer is equal to or less than an upper limit. By calculating the thickness based on this reflectance spectrum, a reflectance spectrum can be generated that includes components of light reflected from the light-irradiated surface of the surface layer and components of light reflected from the interface between the surface layer and the lower layer, while reducing components of light reflected from the interface of the lower layer opposite the interface. Therefore, the generated reflectance spectrum can be used to more accurately calculate the thickness of the surface layer. Therefore, the thickness of the surface layer of a multilayer target sample can be more accurately measured.
[0018] (6) In the above (5), the generating unit may generate the reflectance spectrum in the wavelength range in which, within the thickness range of the surface layer, the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined threshold value, and the round-trip internal transmittance of the layer consisting of the surface layer and the lower layer is equal to or less than the threshold value.
[0019] With this configuration, it is possible to generate a reflectance spectrum that is more effective in thickness measurement, taking into consideration the detection limit based on noise, dynamic range, etc. Specifically, for example, it is possible to generate a reflectance spectrum in which the level of reflected light reflected at the interface between the surface layer and the lower layer is equal to or higher than the noise level, and the level of reflected light reflected at the interface between the lower layer and another lower layer is equal to or lower than the noise level.
[0020] (7) In order to solve the above problem, a manufacturing method of a spectrometer according to a certain aspect of the present invention is a manufacturing method of a spectrometer used to measure the thickness of a surface layer of a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, the manufacturing method including the steps of: acquiring first correspondence information indicating the correspondence relationship between wavelength and round-trip internal transmittance of the surface layer; acquiring second correspondence information indicating the correspondence relationship between wavelength and round-trip internal transmittance of a layer formed by combining the surface layer and the lower layer; and setting a spectroscopic wavelength range of the spectrometer that separates light irradiated from the surface layer side of the target sample and reflected from the target sample based on the acquired first correspondence information and second correspondence information; and in the step of setting the spectroscopic wavelength range, the spectroscopic wavelength range is set so that the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the layer formed by combining the surface layer and the lower layer is equal to or less than a predetermined upper limit.
[0021] In this way, by setting a lower limit value for the round-trip internal transmittance of the surface layer and an upper limit value for the round-trip internal transmittance of the layer comprising the surface layer and the lower layer, and by setting a spectral wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than the lower limit value and the round-trip internal transmittance of the layer comprising the surface layer and the lower layer is equal to or less than the upper limit value, the fabricated spectrometer can be used to generate a reflected light spectrum that includes components of light reflected from the light-irradiated surface of the surface layer and components of light reflected from the interface between the surface layer and the lower layer, while reducing components of light reflected from the interface on the opposite side of the lower layer. Therefore, the thickness of the surface layer can be calculated more accurately using the reflectance spectrum, which is an interference waveform of the surface layer generated using the reflected light spectrum. Therefore, the thickness of the surface layer of a multilayered target sample can be measured more accurately.
[0022] (8) In the above (7), the method for manufacturing the spectrometer may further include a step of acquiring a thickness range of the surface layer, and in the step of setting the spectroscopic wavelength range, the spectroscopic wavelength range may be set within a wavelength range between a first wavelength, which is the wavelength at which the round-trip internal transmittance of the surface layer reaches a predetermined threshold when the thickness of the surface layer is the maximum value of the thickness range, and a second wavelength, which is the wavelength at which the round-trip internal transmittance of the layer formed by combining the surface layer and the lower layer reaches the threshold when the thickness of the surface layer is the minimum value of the thickness range.
[0023] With this configuration, it is possible to determine the specifications of a spectrometer capable of generating a reflected light spectrum that is more effective in thickness measurement, taking into consideration the detection limit based on noise, dynamic range, etc. Specifically, for example, it is possible to determine the specifications of a spectrometer capable of generating a reflected light spectrum in which the level of reflected light reflected at the interface between the surface layer and the lower layer is equal to or higher than the noise level, and the level of reflected light reflected at the interface between the lower layer and another lower layer is equal to or lower than the noise level.
[0024] (9) In order to solve the above problem, a thickness calculation method according to a certain aspect of the present invention is a thickness calculation method in a thickness calculation device used to measure the thickness of a surface layer of a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, the thickness calculation method including the steps of: acquiring a reflected light spectrum of light irradiated from the surface layer side of the target sample and reflected from the target sample; generating a reflectance spectrum of the target sample based on the acquired reflected light spectrum; and calculating the thickness of the surface layer based on the generated reflectance spectrum, wherein in the step of generating the reflectance spectrum, the reflectance spectrum is generated in a wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the combined layer of the surface layer and the lower layer is equal to or less than a predetermined upper limit.
[0025] In this way, by generating a reflectance spectrum in a wavelength range where the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit and the round-trip internal transmittance of the combined surface layer and lower layer is equal to or less than an upper limit based on the reflected light spectrum of the reflected light of the target sample, and then calculating the thickness based on the reflectance spectrum, it is possible to generate a reflectance spectrum that includes components of light reflected from the light-irradiated surface of the surface layer and components of light reflected from the interface between the surface layer and the lower layer, while reducing components of light reflected from the interface of the lower layer opposite the interface. Therefore, the generated reflectance spectrum can be used to more accurately calculate the thickness of the surface layer. Therefore, the thickness of the surface layer of a target sample with a multilayer structure can be more accurately measured.
[0026] According to the present invention, the thickness of the surface layer of a target sample having a multi-layer structure can be measured more accurately.
[0027] FIG. 1 is a diagram showing the configuration of a thickness measurement system according to a first embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a thickness calculation device according to the first embodiment of the present invention. FIG. 3 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 4 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 5 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 6 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 7 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 8 is a diagram showing a simulation result of thickness measurement of a target sample using a thickness measurement system according to a comparative example. FIG. 9 is a diagram showing the configuration of a spectrometer according to the first embodiment of the present invention. FIG. 10 is a diagram showing a simulation result of round-trip internal transmittance of a surface layer. FIG. 11 is a diagram showing the extinction coefficient of silicon. FIG. 12 shows a reflectance spectrum SR generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 13 shows a reflectance spectrum SR generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 14 shows a reflectance spectrum SR generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 15 shows a power spectrum generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 16 shows a power spectrum generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 17 shows a power spectrum generated in the thickness measurement system according to the first embodiment of the present invention. FIG. 18 is a flowchart showing a method for manufacturing a spectrometer in the thickness measurement system according to the first embodiment of the present invention. FIG. 19 is a diagram showing the configuration of a thickness measurement system according to a second embodiment of the present invention. FIG. 20 is a diagram showing the configuration of a thickness calculation device according to the second embodiment of the present invention. FIG. 21 is a flowchart defining an example of an operating procedure when the thickness calculation device according to the second embodiment of the present invention calculates the thickness of a surface layer.
[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.
[0029] 1 is a diagram showing the configuration of a thickness measurement system according to a first embodiment of the present invention. Referring to Fig. 1, the thickness measurement system 301 includes a light source 50, a macro optical system 60, a spectroscope 101, and a thickness calculation device 201.
[0030] The thickness measurement system 301 is a spectral interference measurement system, and is used to measure the thickness of a surface layer Sa of a target sample P having a multilayer structure in which a surface layer Sa and a lower layer Sb are laminated. The surface of the surface layer Sa is the main surface Pm of the target sample P. For example, the lower limit of the thickness range Rth of the surface layer Sa to be measured is 1 μm or more, and the upper limit of the thickness range Rth is 20 μm or less. The shape of the target sample P may be a wafer shape, a rectangular shape, or a film shape.
[0031] The target sample P includes a surface layer Sa and multiple lower layers Sb. For example, the surface layer Sa is a silicon layer, and the lower layers Sb are silicon layers coated with a silicon oxide thin film. For example, the target sample P has a repeating layer structure as the lower layers Sb in which multiple silicon layers coated with a silicon oxide thin film are stacked from the surface layer Sa side. In other words, the target sample P has a repeating layer structure as the lower layers Sb in which, from the surface layer Sa side, silicon oxide layers as coatings and silicon layers are alternately stacked. Note that the target sample P may also have a configuration including one lower layer Sb. Hereinafter, the lower layer Sb adjacent to the surface layer Sa, i.e., the lower layer Sb directly below the surface layer Sa, will also be referred to as the "adjacent lower layer Sb."
[0032] The light source 50 emits light used to measure the thickness of the surface layer Sa. The light source 50 emits light including multiple wavelengths. The spectrum of the light emitted by the light source 50 is a continuous spectrum. The range of wavelengths of the light emitted by the light source 50 includes the spectral wavelength range Rs1 of the spectroscope 101. The light source 50 is, for example, a halogen lamp.
[0033] The macro optical system 60 irradiates the target sample P with light from the light source 50 from the surface layer Sa side, and guides the reflected light of the irradiated light from the target sample P to the spectroscope 101. More specifically, the macro optical system 60 includes a Y-shaped optical fiber 61 and a probe 62. The probe 62 is provided at a first end of the Y-shaped optical fiber 61. A second end of the Y-shaped optical fiber 61 is bifurcated. A branched portion 61A of the Y-shaped optical fiber 61 is connected to the light source 50. A branched portion 61B of the Y-shaped optical fiber 61 is connected to the spectroscope 101.
[0034] Light emitted from the light source 50 is irradiated onto the main surface Pm of the target sample P via the Y-shaped optical fiber 61 and the probe 62. The light irradiated onto the main surface Pm is reflected from the target sample P and guided to the spectrometer 101 via the probe 62 and the Y-shaped optical fiber 61. Note that the thickness measurement system 301 may be configured to include an optical system including a lens, a beam splitter, etc., instead of the macro optical system 60.
[0035] The spectroscope 101 generates a reflected light spectrum SL including a spectral wavelength range Rs1 by spectrally dividing the light reflected from the target sample P. As an example, the spectroscope 101 generates a reflected light spectrum SL in the spectral wavelength range Rs1 by spectrally dividing the light reflected from the target sample P. The spectroscope 101 transmits the generated reflected light spectrum SL to the thickness calculation device 201.
[0036] 2 is a diagram showing the configuration of a thickness calculation device according to a first embodiment of the present invention. Referring to FIG. 2, thickness calculation device 201 includes a receiving unit 21, a generating unit 22, and a calculating unit 23. Receiving unit 21 is an example of an acquiring unit. Some or all of receiving unit 21, generating unit 22, and calculating unit 23 are realized by, for example, a processing circuit including one or more processors.
[0037] The receiving unit 21 receives, from the spectroscope 101 , a reflected light spectrum SL from the target sample P irradiated with light from the surface layer Sa side, and outputs the received reflected light spectrum SL to the generating unit 22 .
[0038] The generation unit 22 generates a reflectance spectrum SR of the target sample P based on the reflected light spectrum SL received from the receiving unit 21. More specifically, the generation unit 22 generates the reflectance spectrum SR by dividing the reflected light spectrum SL by the irradiated light spectrum of the light irradiated onto the target sample P. The generation unit 22 outputs the generated reflectance spectrum SR to the calculation unit 23.
[0039] The calculation unit 23 calculates the thickness of the surface layer Sa based on the reflectance spectrum SR generated by the generation unit 22. For example, the calculation unit 23 calculates the thickness of the surface layer Sa by analyzing the reflectance spectrum SR according to the FFT (Fast Fourier Transform) method. More specifically, the calculation unit 23 generates a power spectrum of the reflectance spectrum SR by performing FFT processing on the reflectance spectrum SR. Then, the calculation unit 23 identifies a thickness that meets given selection conditions from the generated power spectrum as the thickness of the surface layer Sa.
[0040] [Problem] There is a demand for a technique that can more accurately measure the thickness of the surface layer Sa of a target sample P having a multilayer structure.
[0041] More specifically, in general, in order to measure the thickness of a film, a spectral interference measurement system preferably generates a reflectance spectrum SR in a wavelength range where the internal transmittance of the film is high by separating light irradiated onto the main surface of the film from the outside and reflecting the light from the film, and then calculates the thickness based on the reflectance spectrum SR. In particular, when measuring the thickness of a relatively thick film, it is preferable to calculate the thickness based on a reflectance spectrum SR that shows a sufficiently strong reflected light from the surface opposite to the main surface where the light is irradiated, in the wavelength range where the internal transmittance of the film is high.
[0042] Therefore, when measuring the thickness of a silicon film, for example, a conventional thickness measurement system generates a reflected light spectrum SL using a spectrometer having a spectral wavelength range of 1000 nm or more, in which the extinction coefficient of the silicon film is close to zero, and calculates the thickness of the silicon layer based on the generated reflected light spectrum SL.
[0043] 3 to 8 are diagrams showing simulation results of thickness measurement of a target sample using a thickness measurement system according to a comparative example.
[0044] 3 to 5 show reflectance spectra SR generated by a comparative thickness measurement system equipped with a spectrometer having a spectral wavelength range of 1000 nm or more and sufficient wavelength resolution. In FIGS. 3 to 5, the horizontal axis represents wavelength [nm], and the vertical axis represents reflectance. FIG. 3 shows the reflectance spectrum SR of a target sample P1, which includes a 1 μm silicon layer as a surface layer Sa and six alternating layers of 5 μm silicon oxide layers and 21 μm silicon layers as lower layers Sb from the surface layer Sa side. FIG. 4 shows the reflectance spectrum SR of a target sample P2, which includes a 10 μm silicon layer as a surface layer Sa compared to the target sample P1. FIG. 5 shows the reflectance spectrum SR of a target sample P3, which includes a 20 μm silicon layer as a surface layer Sa compared to the target sample P1.
[0045] 6 to 8 show power spectra generated in a thickness measurement system according to a comparative example. In each of the comparative examples, the horizontal axis represents thickness [μm] and the vertical axis represents intensity. Each of the comparative examples shows the power spectrum of the reflectance spectrum SR shown in each of the comparative examples shown in FIGS. 3 to 5.
[0046] 6 to 8 , the thickness measurement system according to the comparative example cannot accurately measure the thickness of the surface layer Sa of the target sample P1. More specifically, in the power spectra of the target samples P1, P2, and P3 generated by the thickness measurement system according to the comparative example, the thickness corresponding to the maximum intensity is approximately 2 μm. Therefore, the measurement result of the thickness of the surface layer Sa by the thickness measurement system according to the comparative example is approximately 2 μm, even though the actual thickness of the surface layer Sa is 1 μm, 10 μm, or 20 μm.
[0047] As described above, when the thickness measurement system according to the comparative example is used to measure the thickness of the target samples P1, P2, and P3 having a multilayer structure, it is difficult to measure the thickness of the surface layer Sa. Moreover, even if the reflectance spectrum SR could be separated into layers, it is difficult to identify which layer the thickness calculated based on the reflectance spectrum SR represents.
[0048] Furthermore, in the technology described in Patent Document 1, the substrate film must have a transmittance in a predetermined wavelength band that is smaller than that of the coating film, and measurement is not possible if the coating film has a transmittance smaller than that of the substrate film. Note that, in the technology described in Patent Document 1, when multiple layers are stacked on one side of the substrate film, it is not possible to measure the thickness of the surface layer of the multiple layers.
[0049] Furthermore, Patent Document 2 describes a technique for suppressing light from the back surface of an object to be measured from appearing as stray light by using a Cassegrain-type reflective objective lens. However, the technique described in Patent Document 2 has significant design constraints.
[0050] Therefore, the thickness measurement system 301 according to the embodiment of the present invention solves the above problem by having the following configuration.
[0051] (Spectrometer) Fig. 9 is a diagram showing the configuration of a spectrometer according to the first embodiment of the present invention. Referring to Fig. 9, spectrometer 101 includes slit 11 and spectroscopic unit 12. Spectroscopic unit 12 includes diffraction grating 12A, detection unit 12B, collimating mirror 12C, and focus mirror 12D. Slit 11 is an example of a light receiving unit.
[0052] The slit 11 receives light reflected from the target sample P, which is light irradiated from the surface layer Sa side of the target sample P. More specifically, the slit 11 receives the light reflected from the target sample P via the branching portion 61B of the Y-shaped optical fiber 61. The reflected light from the target sample P that enters the inside of the spectroscope 101 from the slit 11 is collimated into parallel light by the collimating mirror 12C.
[0053] The spectroscopic unit 12 separates the reflected light from the target sample P to generate a reflected light spectrum SL.
[0054] More specifically, the light that has been collimated by the collimating mirror 12C is guided to the diffraction grating 12A. The diffraction grating 12A separates the incident light into different diffraction angles for each wavelength.
[0055] The light separated by the diffraction grating 12A into different angles for each wavelength is focused by the focus mirror 12D at different positions for each wavelength in the detecting section 12B.
[0056] For example, the detector 12B is a linear image sensor composed of a plurality of detector elements arranged in a line. Such detector elements may be, for example, a charge-coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. Each detector element in the detector 12B receives light that has been dispersed by the diffraction grating 12A and focused by the focus mirror 12D.
[0057] The detection unit 12B generates a reflected light spectrum SL indicating the relationship between wavelength and intensity of the light received on the light receiving surface of each detection element, and transmits the generated reflected light spectrum SL to the thickness calculation device 201.
[0058] For example, the wavelength resolution of the reflected light spectrum SL generated by the spectroscopic section 12 satisfies the following formulas (1) and (2).
[0059] Here, R1 is the optical resolution, R2 is the pixel resolution, λ1 is the wavelength corresponding to the maximum intensity value M1 in the reflected light spectrum SL, and λ2 is the wavelength corresponding to the maximum intensity value M2 in the reflected light spectrum SL. The maximum intensity value M2 is a maximum value that is greater than the maximum intensity value M1 and is adjacent to the maximum intensity value M1.
[0060] The spectroscopic unit 12 generates a reflected light spectrum SL in a spectral wavelength range Rs1 in which the round-trip internal transmittance Ia(d), which is the round-trip internal transmittance I(d) of the surface layer Sa, is equal to or greater than a predetermined lower limit, and the round-trip internal transmittance Iab(d), which is the round-trip internal transmittance I(d) of the layer formed by combining the surface layer Sa and the adjacent lower layer Sb, is equal to or less than a predetermined upper limit. Here, the round-trip internal transmittance Iab(d) corresponds to the round-trip internal transmittance of a silicon layer having a thickness equal to the sum of the thickness of the surface layer Sa and the thickness of the silicon layer in the adjacent lower layer Sb.
[0061] FIG. 10 is a diagram showing the simulation results of the round-trip internal transmittance. In FIG. 10, the horizontal axis represents wavelength [nm], and the vertical axis represents the round-trip internal transmittance. The solid line in FIG. 10 represents the round-trip internal transmittance I(1), which is the round-trip internal transmittance I(d) of a 1 μm silicon layer. The dashed line in FIG. 10 represents the round-trip internal transmittance I(20), which is the round-trip internal transmittance I(d) of a 20 μm silicon layer. The dashed line in FIG. 10 represents the round-trip internal transmittance I(21), which is the round-trip internal transmittance I(d) of a 21 μm silicon layer. Here, the round-trip internal transmittance I(1) is the round-trip internal transmittance of a 1 μm silicon layer, and therefore corresponds to the internal transmittance of a 2 μm silicon layer. Furthermore, the round-trip internal transmittance I(20) is the round-trip internal transmittance of a 20 μm silicon layer, and therefore corresponds to the internal transmittance of a 40 μm silicon layer. Furthermore, the round-trip internal transmittance I(21) is the round-trip internal transmittance of a 21 μm silicon layer, and therefore corresponds to the internal transmittance of a 42 μm silicon layer.
[0062] 10 , the spectroscopic unit 12 generates a reflected light spectrum SL in a spectral wavelength range Rs1 where, within a thickness range Rth, the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than a predetermined threshold Th1 and the round-trip internal transmittance Iab(d) of the combined layer of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the threshold Th1. The threshold Th1 is an example of a lower limit and an example of an upper limit.
[0063] As an example, when the design value of the thickness of the adjacent lower layer Sb is 20 μm and the design value of the thickness of the surface layer Sa is 1 μm, the spectral wavelength range Rs1 is set within a wavelength range between the wavelength λa at which the round-trip internal transmittance Ia(1) of the surface layer Sa reaches the threshold value Th1 and the wavelength λb at which the round-trip internal transmittance Iab(21) of the layer formed by combining the surface layer Sa and the adjacent lower layer Sb reaches the threshold value Th1. The wavelength λa is an example of a first wavelength. The wavelength λb is an example of a second wavelength. The threshold value Th1 is a value less than 1. The threshold value Th1 is, for example, 0.001. Note that the spectral wavelength range Rs1 may also be set within a wavelength range between the wavelength λa at which the round-trip internal transmittance Ia(1) reaches the threshold value Th1 and the wavelength λb at which the round-trip internal transmittance Iab(21) reaches a threshold value Th2 different from the threshold value Th1.
[0064] Furthermore, for example, the spectroscopic unit 12 generates a reflected light spectrum SL in a spectroscopic wavelength range Rs1 in which, within the thickness range Rth, the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than the noise level in the thickness calculation device 201, and the combined round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the noise level in the thickness calculation device 201. That is, the spectroscopic unit 12 generates a reflected light spectrum SL in a spectroscopic wavelength range Rs1 in which, within the thickness range Rth, the level of reflected light that has passed through the surface layer Sa and been reflected at the interface between the surface layer Sa and the adjacent lower layer Sb is equal to or greater than the noise level in the thickness calculation device 201, and the level of reflected light that has passed through the surface layer Sa and the adjacent lower layer Sb and been reflected at the interface between the adjacent lower layer Sb and another lower layer Sb is equal to or less than the noise level in the thickness calculation device 201.
[0065] More specifically, the spectral wavelength range Rs1 is a wavelength range in which a sufficient number of interference waves can be obtained for FFT analysis in a wavelength range in which the round-trip internal transmittance Ia(d) is equal to or greater than the noise level in the thickness calculation device 201, and is also a wavelength range in which the combined round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the noise level in the thickness calculation device 201.
[0066] For example, the spectral wavelength range Rs1 is a wavelength range in which the absolute value of the change in the round-trip internal transmittance of the surface layer Sa with respect to wavelength is equal to or greater than a predetermined value. That is, the spectral wavelength range Rs1 of the spectroscopic unit 12 is a wavelength range that does not include wavelengths equal to or greater than the wavelength λc, at which the round-trip internal transmittance Ia(d) of the surface layer Sa changes very little, and does not include the ultraviolet region, where very little light is transmitted. In other words, the spectral wavelength range Rs1 of the spectroscopic unit 12 is a wavelength range shorter than the wavelength λc. Furthermore, for example, the spectral wavelength range Rs1 includes at least a portion of the visible light region.
[0067] Furthermore, for example, the spectral wavelength range Rs1 of the spectroscopic unit 12 is a wavelength range in which the absolute value of the change in the extinction coefficient of the material constituting the surface layer Sa with respect to wavelength is equal to or greater than a predetermined value. That is, the spectral wavelength range Rs1 of the spectroscopic unit 12 is a wavelength range shorter than the wavelength at which the decrease in the extinction coefficient of silicon, which is the material constituting the surface layer Sa, converges, and does not include a range in which the extinction coefficient is extremely large.
[0068] Fig. 11 is a diagram showing the extinction coefficient of silicon. In Fig. 11, the horizontal axis represents wavelength [nm], and the vertical axis represents the extinction coefficient. Referring to Fig. 11, the designer of the spectrometer 101 performs the following process to determine the specifications. That is, the designer of the spectrometer 101 obtains the extinction coefficient of silicon, which is the material that constitutes the surface layer Sa and the adjacent lower layer Sb.
[0069] The designer of the spectrometer 101 also obtains the thickness range Rth of the surface layer Sa to be measured. The thickness range Rth is the range of thicknesses that can be measured by the thickness measurement system 301. The designer of the spectrometer 101 may set the thickness range Rth according to the target sample P, or may set the thickness range Rth according to the requests of the user of the thickness measurement system 301. Furthermore, for example, the designer of the spectrometer 101 further obtains the thickness range of the adjacent lower layer Sb.
[0070] Then, based on the acquired extinction coefficient and thickness range Rth, the designer of the spectrometer 101 creates correspondence information X1 indicating the correspondence relationship between the wavelength of light incident on the surface layer Sa and the round-trip internal transmittance Ia(d) of the surface layer Sa. Furthermore, based on the acquired extinction coefficient, thickness range Rth, and thickness of the adjacent lower layer Sb, the designer of the spectrometer 101 creates correspondence information X2 indicating the correspondence relationship between the wavelength of light incident on the surface layer Sa and the round-trip internal transmittance Iab(d) of the combined layer of the surface layer Sa and the adjacent lower layer Sb. For example, the designer of the spectrometer 101 calculates the round-trip internal transmittance Ia(d) at the lower limit of the thickness range Rth and the round-trip internal transmittance Ia(d) at the upper limit of the thickness range Rth according to the following formula (3):
[0071] Here, d is the thickness of the surface layer Sa, and α is the absorption coefficient, which is expressed by the following formula (4).
[0072] Here, λ is the wavelength of light irradiated onto the surface layer Sa from the light source 50. k(λ) is the extinction coefficient of light with wavelength λ.
[0073] Based on the correspondence information X1 and X2, the designer of the spectrometer 101 sets a spectral wavelength range Rs1 in which the round-trip internal transmittance I(d) of the surface layer Sa is equal to or greater than the threshold value Th1 and the round-trip internal transmittance Iab(d) of the layer formed by combining the surface layer Sa and the adjacent lower layer Sb is equal to or less than the threshold value Th1. As an example, as described above, the designer of the spectrometer 101 sets the spectral wavelength range Rs1 within the wavelength range between the wavelength λa at which the round-trip internal transmittance Ia(1) reaches the threshold value Th1 and the wavelength λb at which the round-trip internal transmittance Iab(21) reaches the threshold value Th1.
[0074] For example, based on the correspondence information X1 and X2, the designer of the spectrometer 101 sets a spectral wavelength range Rs1 in which the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than the noise level in the thickness calculation device 201, the combined round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the noise level in the thickness calculation device 201, and a sufficient number of interference wavenumbers of the surface layer Sa can be obtained for FFT analysis. In other words, the spectral wavelength range Rs1 is set so that only an interference waveform can be obtained in which the combined round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb does not affect the power spectrum obtained by FFT analysis of the interference waveform obtained from the surface layer Sa.
[0075] 12 to 14 show reflectance spectra SR generated by a thickness measurement system according to the first embodiment of the present invention. Figures 12 to 14 also show reflectance spectra SR generated by a thickness measurement system 301 including a spectrometer 101 having a spectral wavelength range Rs1 of 650 nm or more and 800 nm or less, which is set based on the thickness range Rth of the surface layer Sa. In Figures 12 to 14, the horizontal axis represents wavelength [nm], and the vertical axis represents reflectance. Figures 12 to 14 also show reflectance spectra SR for the above-described target samples P1, P2, and P3, respectively.
[0076] 15 to 17 show power spectra generated by the thickness measurement system according to the first embodiment of the present invention. In each of the figures, the horizontal axis represents thickness [μm] and the vertical axis represents intensity. Each of the figures shows the power spectrum of the reflectance spectrum SR shown in each of the figures.
[0077] 15 to 17, the thickness measurement system 301 can accurately measure the thickness of the surface layer Sa of the target sample P1.
[0078] More specifically, the thickness corresponding to the maximum intensity is approximately 1 μm in the power spectrum of the target sample P1 generated by the thickness measurement system 301. Therefore, the measurement result of the thickness of the surface layer Sa by the thickness measurement system 301 is a value that is approximately equal to the actual thickness of the surface layer Sa.
[0079] Furthermore, in the power spectrum of the target sample P2 generated by the thickness measurement system 301, the thickness corresponding to the maximum intensity is approximately 10 μm. Therefore, the measurement result of the thickness of the surface layer Sa by the thickness measurement system 301 is a value that is approximately equal to the actual thickness of the surface layer Sa.
[0080] Furthermore, in the power spectrum of the target sample P3 generated by the thickness measurement system 301, the thickness corresponding to the maximum intensity is approximately 20 μm. Therefore, the measurement result of the thickness of the surface layer Sa by the thickness measurement system 301 is a value that is approximately equal to the actual thickness of the surface layer Sa.
[0081] 18 is a flowchart showing a method for manufacturing the spectroscope in the thickness measurement system according to the first embodiment of the present invention. The designer of the spectroscope 101 performs the following process to determine the specifications.
[0082] Referring to FIG. 18, first, the designer of the spectrometer 101 obtains the extinction coefficient of silicon, which is the material constituting the surface layer Sa and the adjacent lower layer Sb (step S11).
[0083] Next, the designer of the spectrometer 101 obtains design values for the thickness range Rth of the surface layer Sa to be measured and the thickness of the adjacent lower layer Sb (step S12).
[0084] Next, the designer of the spectrometer 101 creates correspondence information X1 indicating the correspondence relationship between the wavelength of light incident on the surface layer Sa and the round-trip internal transmittance Ia(d) of the surface layer Sa based on the extinction coefficient and the thickness range Rth. The correspondence information X1 is information indicating the wavelength range in which a sufficient number of interference wavenumbers of the surface layer Sa can be obtained for FFT analysis, as well as the spectrometer resolution. For example, the designer of the spectrometer 101 calculates the round-trip internal transmittance Ia(1) of the surface layer Sa at the lower limit of the thickness range Rth and the round-trip internal transmittance Ia(20) of the surface layer Sa at the upper limit of the thickness range Rth (step S13).
[0085] Next, the designer of the spectrometer 101 creates correspondence information X2 that indicates the correspondence relationship between the wavelength of light incident on the surface layer Sa and the round-trip internal transmittance Iab(d) of the combined layer of the surface layer Sa and the adjacent lower layer Sb, based on the extinction coefficient, the thickness range Rth, and the thickness of the adjacent lower layer Sb. For example, the designer of the spectrometer 101 calculates the combined round-trip internal transmittance Iab(21) of the surface layer Sa and the adjacent lower layer Sb at the lower limit of the thickness range Rth, and the combined round-trip internal transmittance Iab(40) of the surface layer Sa and the adjacent lower layer Sb at the upper limit of the thickness range Rth (step S14).
[0086] Next, based on the correspondence information X1 and X2, the designer of the spectrometer 101 sets a spectral wavelength range Rs1 in which the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than the threshold value Th1 and the round-trip internal transmittance Iab(d) of the combined layer of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the threshold value Th1 within the thickness range Rth. More specifically, the designer of the spectrometer 101 sets the spectral wavelength range Rs1 within a wavelength range between the wavelength λa at which the round-trip internal transmittance Ia(d) is equal to the threshold value Th1 when the thickness of the surface layer Sa is the maximum value within the thickness range Rth and the wavelength λb at which the round-trip internal transmittance Iab(d) is equal to the threshold value Th1 when the thickness of the surface layer Sa is the minimum value within the thickness range Rth (step S15).
[0087] For example, in step S14, the designer of the spectrometer 101 sets a spectral wavelength range Rs1 that satisfies the conditions that the round-trip internal transmittance Ia(d) is equal to or greater than the noise level in the thickness calculation device 201, and the round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb combined is equal to or less than the noise level in the thickness calculation device 201. Note that the designer of the spectrometer 101 may set a spectral wavelength range Rs1 that does not satisfy these conditions if the specifications of the thickness measurement system 301 allow it.
[0088] Furthermore, for example, in step S14, the designer of the spectrometer 101 sets a spectral wavelength range Rs1 between a wavelength λa at which the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than the noise level in the thickness calculation device 201 and a wavelength λb at which the combined round-trip internal transmittance Iab(d) of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the noise of the measurement device detection unit. Note that the designer of the spectrometer 101 may set a spectral wavelength range Rs1 that exceeds the range between the wavelengths λa and λb if permitted by the specifications of the thickness measurement system 301.
[0089] Furthermore, for example, in step S14, the designer of the spectrometer 101 compares the power spectrum obtained by FFT analysis of the interference waveform of the surface layer Sa with the power spectrum obtained by FFT analysis of the interference waveform of the adjacent lower layer Sb and the power spectrum obtained by FFT analysis of the interference waveform of the combined layer of the surface layer Sa and the adjacent lower layer Sb, and sets a spectral wavelength range Rs1 that satisfies the condition that it is sufficiently selectable in accordance with a predetermined selection condition. Note that the designer of the spectrometer 101 may also set a spectral wavelength range Rs1 that does not satisfy this condition if it is permitted by the specifications of the thickness measurement system 301.
[0090] Furthermore, for example, in step S14, the designer of the spectrometer 101 sets a spectroscopic wavelength range Rs1 and a resolution that satisfy the following conditions: when it is assumed that the thickness of the surface layer Sa is the lower limit of the thickness range Rth, the wavelength range and resolution satisfy the conditions that a sufficient number of interference wavenumbers for analysis can be obtained in the wavelength range where the level of the interference waveform of the surface layer Sa is equal to or higher than the noise level in the thickness calculation device 201, and when it is assumed that the thickness of the surface layer Sa is the upper limit of the thickness range Rth, the wavelength range and resolution satisfy the conditions that a sufficient number of interference wavenumbers for analysis can be obtained in the wavelength range where the level of the interference waveform of the surface layer Sa is equal to or higher than the noise level in the thickness calculation device 201. Note that the designer of the spectrometer 101 may set a spectroscopic wavelength range Rs1 that does not satisfy these conditions if it is permissible in terms of the specifications of the thickness measurement system 301.
[0091] In the spectrometer 101 according to the first embodiment of the present invention, the spectroscopic wavelength range Rs1 of the spectroscopic unit 12 is set within a wavelength range between the wavelength λa at which the round-trip internal transmittance Ia(d) reaches the threshold value Th1 and the wavelength λb at which the round-trip internal transmittance Iab(d) reaches the threshold value Th1, but this is not limited to this. The spectroscopic wavelength range Rs1 may include wavelengths shorter than the wavelength λa if permitted by the specifications of the thickness measurement system 301.
[0092] Next, other embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.
[0093] Second Embodiment This embodiment relates to a thickness measurement system 302 that limits the wavelength range of the reflected light spectrum SL used to generate the reflectance spectrum SR, as compared with the thickness measurement system 301 according to the first embodiment. Other than the contents described below, the thickness measurement system 302 is the same as the thickness measurement system 301 according to the first embodiment.
[0094] 19 is a diagram showing the configuration of a thickness measurement system according to the second embodiment of the present invention. Compared to thickness measurement system 301, thickness measurement system 302 includes spectrometer 102 instead of spectrometer 101, and thickness calculation device 202 instead of thickness calculation device 201.
[0095] The spectroscope 102 separates the light reflected from the target sample P to generate a reflected light spectrum SL in a spectral wavelength range Rs2. The spectral wavelength range Rs2 is a wavelength range that includes the spectral wavelength range Rs1 of the spectroscope 101 in the thickness measurement system 301 but is wider than the spectral wavelength range Rs1. In other words, if the spectral wavelength range Rs1 is a range of 650 nm to 800 nm, the spectral wavelength range Rs2 is, for example, a range of 500 nm to 1200 nm. The spectroscope 102 outputs the generated reflected light spectrum SL to the thickness calculation device 202.
[0096] 20 is a diagram showing the configuration of a thickness calculation device according to the second embodiment of the present invention. Compared to thickness calculation device 201, thickness calculation device 202 includes generation unit 24 instead of generation unit 22.
[0097] The generator 24 generates a reflectance spectrum SR in a wavelength range Rr in which the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than a threshold value Th1 and the round-trip internal transmittance Iab(d) of the combined layer of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the threshold value Th1. For example, the wavelength range Rr is the same wavelength range as the spectral wavelength range Rs1 described in the first embodiment.
[0098] More specifically, the generation unit 24 extracts a reflected light spectrum SLp in a wavelength range Rr from the reflected light spectrum SL received from the receiving unit 21. The generation unit 24 generates a reflectance spectrum SRp by dividing the reflected light spectrum SLp by the irradiated light spectrum in the wavelength range Rr of the light irradiated to the target sample P. The generation unit 24 outputs the generated reflectance spectrum SRp to the calculation unit 23.
[0099] The calculation unit 23 calculates the thickness of the surface layer Sa based on the reflectance spectrum SRp generated by the generation unit 24. As a result, the thickness measurement system 302, like the thickness measurement system 301, can accurately measure the thickness of the surface layer Sa of the target sample P1.
[0100] A thickness calculation device according to an embodiment of the present invention includes a computer including a memory, and a processor such as a CPU in the computer reads from the memory and executes a program including some or all of the steps in the following flowcharts and sequences. The program for this device can be installed externally. The program for this device is distributed in a state stored on a recording medium or via a communication line.
[0101] FIG. 21 is a flowchart defining an example of an operation procedure when the thickness calculation device according to the second embodiment of the present invention calculates the thickness of the surface layer.
[0102] Referring to FIG. 21, first, the thickness calculation device 202 receives from the spectroscope 101 the reflected light spectrum SL of the light irradiated from the surface layer Sa side of the target sample P (step S21).
[0103] Next, based on the reflected light spectrum SL, the thickness calculation device 202 generates a reflectance spectrum SRp in a wavelength range Rr in which the round-trip internal transmittance Ia(d) of the surface layer Sa is equal to or greater than the threshold value Th1 and the round-trip internal transmittance Iab(d) of the layer consisting of the surface layer Sa and the adjacent lower layer Sb is equal to or less than the threshold value Th1 (step S22).
[0104] Next, the thickness calculation device 202 calculates the thickness of the surface layer Sa based on the reflectance spectrum SRp (step S23).
[0105] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.
[0106] REFERENCE SIGNS LIST 11 slit 12 spectroscopic section 12A diffraction grating 12B detection section 12C collimating mirror 12D focus mirror 21 receiving section 22, 24 generating section 23 calculating section 50 light source 60 macro optical system 61 Y-shaped optical fiber 61A, 61B branching section 62 probe 101, 102 spectroscope 201, 202 thickness calculation device 301, 302 thickness measurement system P target sample Pm main surface Sa surface layer Sb lower layer λa, λb, λc wavelength Th1 threshold I(1), I(20), I(21) round trip internal transmittance Rs1 spectroscopic wavelength range
Claims
1. A spectrometer used to measure the thickness of the surface layer in a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, A light receiving unit that receives reflected light from the target sample of light irradiated from the surface layer side of the target sample, The system includes a spectrometer that generates a reflected light spectrum by spectrally analyzing the reflected light, The spectrometer generates the reflected light spectrum in a spectral wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit, and the round-trip internal transmittance of the combined surface layer and the underlying layer is equal to or less than a predetermined upper limit.
2. The spectrometer according to claim 1, wherein the spectroscopic unit generates the reflected light spectrum in the spectral wavelength range in which, within the thickness range of the surface layer, the round-trip internal transmittance of the surface layer is greater than or equal to a predetermined threshold, and the round-trip internal transmittance of the combined layer of the surface layer and the underlying layer is less than or equal to the threshold.
3. The aforementioned surface layer is a silicon layer, The spectrometer according to claim 1, wherein the spectroscopic unit generates the reflected light spectrum in the spectral wavelength range of 650 nm or more and 800 nm or less.
4. A spectrometer according to any one of claims 1 to 3, A thickness measurement system comprising a macro-optical system that irradiates the target sample with light from a light source from the surface layer side and guides the reflected light from the target sample to a spectrometer.
5. A thickness calculation device used for measuring the thickness of the surface layer in a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, An acquisition unit that acquires the reflected light spectrum of the light reflected from the target sample by light irradiated from the surface layer side of the target sample, A generation unit generates a reflectance spectrum of the target sample based on the reflected light spectrum acquired by the acquisition unit, The system includes a calculation unit that calculates the thickness of the surface layer based on the reflectance spectrum generated by the generation unit, The generating unit generates the reflectance spectrum in a wavelength range in which the reciprocating internal transmittance of the surface layer is equal to or greater than a predetermined lower limit, and the reciprocating internal transmittance of the combined layer of the surface layer and the lower layer is equal to or less than a predetermined upper limit.
6. The thickness calculation apparatus according to claim 5, wherein the generating unit generates the reflectance spectrum in the wavelength range in which the round-trip internal transmittance of the surface layer is greater than or equal to a predetermined threshold, and the round-trip internal transmittance of the combined layer of the surface layer and the lower layer is less than or equal to the threshold, within the thickness range of the surface layer.
7. A method for manufacturing a spectrometer used to measure the thickness of a surface layer in a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, A step of obtaining first correspondence information showing the correspondence between wavelength and the round-trip internal transmittance of the surface layer, A step of obtaining second correspondence information showing the correspondence between wavelength and the round-trip internal transmittance of the combined surface layer and the underlying layer, The process includes the step of setting the spectral wavelength range of the spectrometer for spectrally analyzing the reflected light from the target sample irradiated from the surface layer side of the target sample, based on the acquired first correspondence information and second correspondence information. A method for manufacturing a spectrometer, comprising the step of setting the spectral wavelength range, wherein the spectral wavelength range is set such that the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit, and the round-trip internal transmittance of the combined surface layer and the lower layer is equal to or less than a predetermined upper limit.
8. The manufacturing method of the spectrometer further includes, The step includes obtaining the thickness range of the surface layer, The method for manufacturing a spectrometer according to claim 7, wherein in the step of setting the spectral wavelength range, the spectral wavelength range is set within a wavelength range between a first wavelength, which is the wavelength at which the round-trip internal transmittance of the surface layer becomes a predetermined threshold when the thickness of the surface layer is the maximum value of the thickness range, and a second wavelength, which is the wavelength at which the round-trip internal transmittance of the combined surface layer and the lower layer becomes the threshold when the thickness of the surface layer is the minimum value of the thickness range.
9. A thickness calculation method for a thickness calculation device used to measure the thickness of the surface layer in a target sample having a multilayer structure in which a surface layer and a lower layer are stacked, The steps include: obtaining the reflected light spectrum of the light reflected from the target sample by light irradiated from the surface layer side of the target sample; A step of generating a reflectance spectrum of the target sample based on the acquired reflected light spectrum, The steps include calculating the thickness of the surface layer based on the generated reflectance spectrum, A thickness calculation method comprising the step of generating the reflectance spectrum, wherein the reflectance spectrum is generated in a wavelength range in which the round-trip internal transmittance of the surface layer is equal to or greater than a predetermined lower limit, and the round-trip internal transmittance of the combined layer of the surface layer and the lower layer is equal to or less than a predetermined upper limit.