Film thickness measuring device and film thickness measuring method

Abstract

This film thickness measurement device measures the film thickness of a sample having a film formed on a substrate, and is provided with: a light source that irradiates the sample with light in a planar manner; an area sensor that captures light from the sample; a calculation unit that derives a measurement parameter relating to the sample on the basis of a signal from the region sensor; a storage unit that stores relationship information between the film thickness and the measurement parameter; and an analysis unit that derives the film thickness of the sample on the basis of the relationship information and the measurement parameters relating to the sample obtained by the calculation unit. The relationship information is derived on the basis of the theoretical reflectance corresponding to the type of the film and the spectral characteristics of the entire film thickness measurement device.

Description

Technical Field

[0001] One aspect of the present disclosure provides a film thickness measuring device and a film thickness measuring method. Background Art

[0002] Patent Document 1 discloses a technique for separating light from an object using a dichroic mirror whose transmittance and reflectance vary according to wavelength, capturing each of the separated lights to obtain a wavelength center, and estimating the film thickness of the object based on the wavelength center. Prior art literature Patent Literature

[0003] Patent Document 1: International Publication No. 2021 / 161986 Summary of the Invention The problem the invention aims to solve

[0004] In the film thickness measurement method using the wavelength centroid described above, the relationship between film thickness and wavelength centroid must be known in advance. One method for determining this relationship is to use a reference sample. In this method, multiple reference samples with varying film thicknesses are prepared, and the wavelength centroid is determined for each. The wavelength centroid is then plotted against the film thickness, and the relationship between the plotted data is derived using a fitting method.

[0005] The relationship between film thickness and wavelength center derived by the above method varies depending on the type of film of the sample being measured and the wavelength of the irradiated light. Therefore, the above method requires, for example, preparing multiple reference samples of different film thicknesses for each film type, which is not convenient.

[0006] One aspect of the present disclosure has been made in view of the above-mentioned actual situation, and an object thereof is to provide a film thickness measuring device and a film thickness measuring method that can easily measure the film thickness of an object. Technical means to solve the problem

[0007] A film thickness measurement device according to one embodiment of the present disclosure measures the thickness of an object having a film formed on a substrate. The device comprises: a light irradiation unit for planarly irradiating the object with light; an imaging unit for capturing light from the object; a calculation unit for deriving measurement parameters related to the object based on a signal from the imaging unit capturing the light; a storage unit for storing relationship information between the film thickness and the measurement parameters; and an analysis unit for deriving the film thickness of the object based on the relationship information and the measurement parameters related to the object obtained by the calculation unit. The relationship information is derived based on a theoretical reflectance corresponding to the type of film and the spectral characteristics of the film thickness measurement device.

[0008] In a film thickness measuring device according to one embodiment of the present invention, relationship information between film thickness and measurement parameters is stored. Furthermore, in the film thickness measuring device, the measurement parameters are derived based on the signal from the camera portion that captures the light from the object, and the film thickness of the object is derived based on the measurement parameters and the above-mentioned relationship information. Here, the relationship information is information derived based on the theoretical reflectivity corresponding to the type of film and the spectral characteristics of the film thickness measuring device, and is information that specifies the correlation between the film thickness and the measurement parameters under specific conditions for the type of film with high precision. Therefore, by deriving the film thickness of the object based on the measurement parameters and relationship information derived based on the imaging results as described above, the film thickness of the object can be derived with high precision. Furthermore, in a film thickness measuring device according to one embodiment of the present invention, since the film thickness of the object is derived using the relationship information obtained in advance (information derived based on the theoretical reflectivity and spectral characteristics), there is no need to perform measurements related to a reference sample, and the film thickness measurement of the object can be simply performed.

[0009] In the above-described film thickness measurement device, the storage unit may store relationship information for each type of film, and the analysis unit may derive the film thickness of the object based on the relationship information corresponding to the type of the object film and the measurement parameters related to the object obtained by the calculation unit. In this manner, by storing relationship information for each type of film and deriving the film thickness of the object based on the relationship information corresponding to the type of the object film and the measurement parameters, film thickness measurement can be performed easily and with high accuracy on objects of various film types.

[0010] The film thickness measurement device may further include an optical element whose transmittance and reflectance vary depending on wavelength within a predetermined wavelength band, separating light from an object by transmission and reflection; and an imaging unit comprising a first camera that captures light reflected by the optical element and outputs a first signal; and a second camera that captures light transmitted through the optical element and outputs a second signal. In this manner, the optical element, whose transmittance and reflectance vary depending on wavelength, separates light from the object. By capturing the separated light beams using the first and second cameras, the ratio of transmitted light to reflected light can be appropriately detected, and information indicating wavelength can be determined from the detected information. By enabling the determination of information indicating wavelengths highly correlated with film thickness, the accuracy of film thickness measurement can be improved.

[0011] In the film thickness measurement device described above, the calculation unit may derive a wavelength centroid as a measurement parameter based on the first signal and the second signal. In this manner, by deriving the wavelength centroid of the measurement parameter based on the first signal from the first camera and the second signal from the second camera, the wavelength centroid that has a high correlation with film thickness can be used as the measurement parameter, thereby improving the accuracy of film thickness measurement.

[0012] In the film thickness measuring device described above, the relationship information may be a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting expected values ​​of the measurement parameter corresponding to each film thickness, which are derived based on theoretical reflectivity and spectral characteristics. By using such a relationship expression as the relationship information, the film thickness of the object can be derived with high accuracy based on the relationship information that accurately defines the correlation between the film thickness and the measurement parameter.

[0013] In the film thickness measuring device described above, the object may include a first film layer stacked on a substrate and a second film layer stacked on the first film layer as films; the storage unit may store relationship information regarding the film thickness of the second film layer and measurement parameters for each combination of the type and thickness of the film of the first layer and the type of the film of the second layer; and the analysis unit may derive the film thickness of the second film of the object based on the relationship information regarding the combination of the type and thickness of the film of the first layer corresponding to the first film of the object and the type of the film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained by the calculation unit. In this manner, by defining the relationship information regarding the film thickness of the second film layer and the measurement parameters for each combination of the type and thickness of the film of the first layer and the type of the film of the second layer, the thickness of the second film may be measured with high accuracy and simplicity when the type and thickness of the first film layer, the type of the second film layer, and the measurement parameters are known.

[0014] A film thickness measuring method according to one embodiment of the present invention is a film thickness measuring method for measuring the film thickness of an object having a film formed on a substrate, and comprises: a light irradiation step of irradiating light onto the object in a planar manner; an imaging step of capturing light from the object; a calculation step of deriving measurement parameters related to the object based on a signal of the imaging of the light in the imaging step; a reading step of reading relationship information from a storage unit storing relationship information between the film thickness and the measurement parameters; and an analysis step of deriving the film thickness of the object based on the relationship information and the measurement parameters related to the object obtained in the calculation step, wherein the relationship information is derived based on a theoretical reflectivity corresponding to the type of the film and the spectral characteristics of the film thickness measuring device.

[0015] In the above-mentioned film thickness measurement method, the storage unit may store relationship information for each type of film, and in the analysis step, the film thickness of the object is derived based on the relationship information corresponding to the type of the film of the object and the measurement parameters related to the object obtained in the calculation step.

[0016] In the above-mentioned film thickness measurement method, it can also be performed in the camera step: photographing the light reflected by the optical element by the first camera and outputting the first signal, wherein the transmittance and reflectance of the optical element vary according to the wavelength in a specified wavelength band, and the light from the object is separated by transmission and reflection; and photographing the light passing through the optical element by the second camera and outputting the second signal.

[0017] In the film thickness measurement method described above, in the calculation step, a wavelength center of gravity may be derived as a measurement parameter based on the first signal and the second signal.

[0018] In the film thickness measurement method, the relationship information may be a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting expected values ​​of the measurement parameter corresponding to each film thickness derived based on theoretical reflectance and spectral characteristics.

[0019] In the above-mentioned film thickness measurement method, the object may also be formed with a first layer, i.e., a first film, stacked on a substrate, and a second layer, i.e., a second film, stacked on the first layer, as films; the storage unit stores relationship information between the film thickness of the second layer and measurement parameters for each combination of the type and film thickness of the film of the first layer and the type of film of the second layer; in the analysis step, the film thickness of the second film of the object is derived based on the relationship information corresponding to the type and film thickness of the film of the first layer corresponding to the first film of the object and the combination of the type of film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained in the operation unit step. Effects of the Invention

[0020] According to the film thickness measuring device and the film thickness measuring method according to one embodiment of the present disclosure, the film thickness of an object can be measured simply. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a diagram schematically showing the film thickness measuring device according to this embodiment. Figure 2 This is a diagram illustrating the relationship between the characteristics of a dichroic mirror and the wavelength of light emitted from a light source. Figure 3 Graphs illustrating the spectrum of light and the characteristics of a tilted dichroic mirror. Figure 4 This is a diagram explaining wavelength shift according to the amount of transmitted light and the amount of reflected light. Figure 5 It is a graph showing the relationship between wavelength and film thickness. Figure 6 This is a diagram schematically showing an example of a configuration for performing an approximate calculation of spectral characteristics. Figure 7 Is explained through Figure 6 A diagram showing an example of a method for estimating spectral characteristics implemented in the configuration shown. Figure 8 This is a diagram schematically showing an example of another configuration for performing an approximate calculation of spectral characteristics. Figure 9 This is a diagram explaining the derivation of expected values ​​of measurement parameters. Figure 10This is a diagram explaining the derivation of a relational expression by curve fitting. Figure 11 This is a diagram for explaining the derivation of film thickness using a relational expression. Figure 12 (a) to (c) are diagrams explaining the derivation of relational expressions for measurement parameters other than the wavelength center of gravity. Figure 13 It is a diagram schematically showing a film thickness measuring device according to a modified example. Figure 14 This is a cross-sectional view schematically showing a sample of a multilayer film structure according to a modified example. Figure 15 (a) is a diagram showing the distribution of the wavelength center of gravity measured for the first layer, Figure 15 (b) is about Figure 15 Graph showing the distribution of the film thickness of the first layer derived from the wavelength center shown in (a). Figure 16 This is a diagram showing the distribution of wavelength centers of gravity measured after the second layer is formed. Figure 17 This figure explains the wavelength center measured after the second layer is formed and the derivation of the second layer thickness based on the first layer thickness. Figure 18 This is a diagram explaining the relationship between the second layer thickness and the wavelength center of gravity for each first layer thickness. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, identical or corresponding parts are denoted by identical reference numerals, and overlapping descriptions are omitted.

[0023] Figure 1 : is a diagram schematically showing a film thickness measuring device 1 of the present embodiment. The film thickness measuring device 1 is a device that irradiates light onto a sample 100 (object) in a planar manner and measures the thickness of a film formed on the sample 100 based on the reflected light from the sample 100. The sample 100 may be a light-emitting element such as an LED, a micro-LED, a μLED, an SLD element, a laser element, a vertical laser element (VCSEL), an OLED, or a light-emitting element that adjusts the emission wavelength by including a fluorescent substance such as nanodots. In addition, the sample 100 may be, for example, an optical film, a thin film facing a display panel, a thin film facing a semiconductor, or the like. The sample 100 is an object having a film 100b formed on the surface of a substrate 100a. In this embodiment, the description is made assuming that only one layer of film 100b is formed on the surface of the substrate 100a in the sample 100. The film 100b is, for example, an oxide film or a nitride film, but may be other films.

[0024] like Figure 1 As shown, the film thickness measuring device 1 includes a light source 10 (light irradiation unit), a half mirror 11 , a field lens 12 , a camera system 20 , and a control device 30 (calculation unit, storage unit, analysis unit).

[0025] The light source 10 irradiates the sample 100 with light in a planar manner (light irradiation step). For example, the light source 10 can irradiate the substantially entire surface of the sample 100 with light in a planar manner. For example, the light source 10 is a light source that can uniformly irradiate the surface of the sample 100, irradiating the sample 100 with diffuse light. The light source 10 can be a planar lighting unit using a white LED, a halogen lamp, or a Xe lamp. The light emitted from the light source 10 is irradiated onto the sample 100 in a planar manner via the half-mirror 11 and the field lens 12.

[0026] Light source 10 irradiates sample 100 with light of wavelengths within a predetermined wavelength band through tilted dichroic mirror 22 (described in detail below) included in camera system 20. Although described in detail below, tilted dichroic mirror 22 is an optical element that separates light from sample 100 by transmitting and reflecting it according to wavelength. The transmittance and reflectance of tilted dichroic mirror 22 within the predetermined wavelength band vary depending on wavelength.

[0027] Figure 2 : is a diagram illustrating the relationship between the characteristics of the tilted dichroic mirror 22 and the wavelength of light emitted from the light source 10. Figure 2 In FIG, the horizontal axis represents the wavelength, and the vertical axis represents the transmittance of the tilted dichroic mirror 22. Figure 2 As shown in the characteristic X4 of the tilted dichroic mirror 22, in the tilted dichroic mirror 22, the transmittance (and reflectance) of light changes gently with the change of wavelength in a predetermined wavelength band X10, and in wavelength bands other than the specific wavelength band, the transmittance (and reflectance) of light remains constant regardless of the change of wavelength. Figure 2 As shown, the light X20 output from the light source 10 includes light with wavelengths within the predetermined wavelength band X10. That is, the light source 10 outputs light with a broad spectrum encompassing the predetermined wavelength band X10. Furthermore, the measured wavelength band (interference peak wavelength) is determined by the material of the film formed on the sample 100 and the measured film thickness range.

[0028] return Figure 1 The half mirror 11 reflects light emitted from the light source 10 toward the sample 100 (specifically, toward the field lens 12 that guides light toward the sample 100), and transmits light from the illuminated sample 100 (specifically, light from the sample 100 through the field lens 12). The field lens 12 is a lens that aligns the direction of light travel.

[0029] The camera system 20 includes a lens 21, a tilted dichroic mirror 22 (optical element), an area sensor 23 (second camera, imaging unit), and an area sensor 24 (first camera, imaging unit). Alternatively, the camera system 20 may include a linear image sensor (detection unit) in place of the area sensor.

[0030] The lens 21 is a lens that collects the light from the sample 100 that is incident through the field lens 12 and the semi-reflecting mirror 11. The lens 21 can be arranged in the front section (upstream) of the tilted dichroic mirror 22, or in the area between the tilted dichroic mirror 22 and the area sensors 23 and 24. In this embodiment, it is assumed that the lens 21 is arranged in the front section (upstream) of the tilted dichroic mirror 22 for description. The lens 21 can be a finite focus lens or an infinite focus lens. In the case where the lens 21 is a finite focus lens, the distance from the lens 21 to the area sensors 23 and 24 is set to a specified value. In the case where the lens 21 is an infinite focus lens, the lens 21 is a collimating lens that converts the light from the sample 100 into parallel light, and is subjected to aberration correction to obtain parallel light. The light output from the lens 21 is incident on the tilted dichroic mirror 22.

[0031] The tilted dichroic mirror 22 is a reflective mirror made of special optical materials and is an optical element that separates light from the sample 100 by transmitting and reflecting it according to wavelength. The tilted dichroic mirror 22 is configured so that the transmittance and reflectance of light in a predetermined wavelength band vary according to wavelength.

[0032] Figure 3 2 is a diagram illustrating the spectrum of light and the characteristics of the tilted dichroic mirror 22. Figure 3 The horizontal axis represents wavelength, and the vertical axis represents spectral intensity (in the case of light spectrum) and transmittance (in the case of tilting the dichroic mirror 22). Figure 3As shown in characteristic X4 of the tilted dichroic mirror 22, within a predetermined wavelength band (the wavelength band from wavelengths λ1 to λ2), the transmittance (and reflectance) of light in the tilted dichroic mirror 22 varies gently with wavelength changes. On the other hand, in wavelength bands outside this predetermined wavelength band (i.e., those lower than wavelength λ1 and those higher than wavelength λ2), the transmittance (and reflectance) of light remains constant regardless of wavelength changes. In other words, within a specific wavelength range (the wavelength range from wavelengths λ1 to λ2), the transmittance of light varies monotonically, increasing (and the reflectance monotonically decreasing) with wavelength changes. Because transmittance and reflectance have a negative correlation—as one increases, the other decreases—hereafter, this term is sometimes simply referred to as "transmittance" rather than "transmittance (and reflectance)." In addition, "the transmittance of light is constant regardless of changes in wavelength" includes not only the case where it is completely constant, but also the case where the change in transmittance relative to a change in wavelength of 1nm is less than 0.1%. On the lower wavelength side than wavelength λ1, the transmittance of light can be approximately 0% regardless of changes in wavelength, and on the higher wavelength side than wavelength λ2, the transmittance of light can be approximately 100% regardless of changes in wavelength. In addition, "the transmittance of light is approximately 0%" includes transmittances of the order of 0%+10%, and "the transmittance of light is approximately 100%" includes transmittances of the order of 100%-10%. In Figure 3 In FIG, waveform X1 represents the waveform of light output from light source 10. Figure 3 As shown in the waveform X1 , the light output from the light source 10 includes light of a wavelength included in a predetermined wavelength band (a wavelength band of wavelengths λ1 to λ2 ) of the tilted dichroic mirror 22 .

[0033] return Figure 1 , the area sensors 23 and 24 capture light from the sample 100 (imaging step). The area sensors 23 and 24 capture light separated by the tilted dichroic mirror 22. The area sensor 23 captures light transmitted through the tilted dichroic mirror 22 and outputs a second signal. The area sensor 24 captures light reflected by the tilted dichroic mirror 22 and outputs a first signal. The wavelength range to which the area sensors 23 and 24 are sensitive corresponds to a prescribed wavelength band in which the transmittance (and reflectance) of light in the tilted dichroic mirror 22 changes according to changes in wavelength. The area sensors 23 and 24 are, for example, monochrome sensors or color sensors. The imaging results (images) obtained by the area sensors 23 and 24 are output to the control device 30 via the above-mentioned first and second signals.

[0034] A bandpass filter (not shown) may be disposed upstream of the area sensors 23 and 24. Such a bandpass filter (not shown) may be, for example, a filter that removes light in wavelength bands other than the aforementioned predetermined wavelength band (a wavelength band in which the transmittance and reflectance of light in the tilted dichroic mirror 22 vary depending on the wavelength).

[0035] The control device 30 is a computer that physically includes memory such as RAM and ROM, a processor (calculation circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The control device 30 functions by executing programs stored in the memory using the computer system's CPU. The control device 30 can be implemented using a microcomputer or an FPGA.

[0036] The control device 30 derives the film thickness of the sample 100 based on the signals from the area sensors 23 and 24 that captured the light, namely the first signal and the second signal. As a process for deriving the film thickness, the control device 30 implements a measurement parameter derivation process based on the signals from the area sensors 23 and 24, and a film thickness derivation process based on the measurement parameters, etc. In addition, as a prerequisite for implementing the film thickness derivation process, the control device 30 stores relationship information between the film thickness and the measurement parameters. The control device 30 has a calculation unit 31, an analysis unit 32, and a storage unit 33 as a functional structure for realizing the above-mentioned various processes and storage. The calculation unit 31 implements the function of the measurement parameter derivation process. The analysis unit 32 implements the function of the film thickness derivation process. The storage unit 33 stores the above-mentioned relationship information. The following describes each function in detail.

[0037] The calculation unit 31 derives measurement parameters related to the sample 100 based on the signals from the area sensors 23 and 24 that captured the light (calculation step). The measurement parameters can be any parameter that correlates with the film thickness. For example, they can be the wavelength center of the light from the sample 100, the intensity of the light transmitted through the tilted dichroic mirror 22, the intensity of the light reflected from the tilted dichroic mirror 22, or the ratio of the intensity of the light transmitted through the tilted dichroic mirror 22 to the intensity of the light reflected from the tilted dichroic mirror 22. The following description assumes that the measurement parameter is the wavelength center of the light from the sample 100.

[0038] The calculation unit 31 can derive the wavelength centroid of light for each pixel as a measurement parameter based on the amount of transmitted light (the intensity of light transmitted through the tilted dichroic mirror 22) determined based on the second signal from the area sensor 23 representing the imaging result of the area sensor 23, and the amount of reflected light (the intensity of light reflected by the tilted dichroic mirror 22) determined based on the first signal from the area sensor 24 representing the imaging result of the area sensor 24. Specifically, the calculation unit 31 derives the wavelength centroid of light for each pixel based on the following equation (1). In the following equation (1), x' represents the wavelength centroid, IT' represents the amount of transmitted light, and IR' represents the amount of reflected light. x′ = (IT′ - IR′) / 2(IT′ + IR′) (1)

[0039] In addition, the arithmetic unit 31 can further derive the wavelength centroid of the light for each pixel in consideration of the center wavelength of the inclined dichroic mirror 22 (the center wavelength of the specified wavelength band) and the width of the inclined dichroic mirror 22. The width of the inclined dichroic mirror 22 is, for example, the wavelength width from the wavelength at which the transmittance is 0% to the wavelength at which the transmittance is 100% in the inclined dichroic mirror 22. In this case, the arithmetic unit 31 can derive the wavelength centroid of each pixel based on the following formula (2). In the following formula (2), x′ represents the wavelength centroid, IT′ represents the amount of transmitted light, IR′ represents the amount of reflected light, λ0 represents the center wavelength of the inclined dichroic mirror 22, and A represents the width of the inclined dichroic mirror 22. x′ = λ0 + A(IT′ - IR′) / 2(IT′ + IR′) (2)

[0040] Figure 4 is a diagram illustrating the wavelength shift corresponding to the amount of transmitted light and the amount of reflected light. When x′ (wavelength centroid) is derived by the above formula (1) or formula (2), as Figure 4 shown, for pixels where IT′ (amount of transmitted light) = IR′ (amount of reflected light), it is assumed that x′ = λ0 (the center wavelength of the inclined dichroic mirror 22). In addition, for pixels where IT′ < IR′, that is, pixels where the amount of reflected light is more than the amount of transmitted light, it is assumed that x′ = λ1 (a wavelength on the shorter wavelength side than λ0). In addition, for pixels where IT′ > IR′, that is, pixels where the amount of transmitted light is more than the amount of reflected light, it is assumed that x′ = λ2 (a wavelength on the longer wavelength side than λ0). Thus, x′ (wavelength centroid) shifts (wavelength shift) based on the amount of transmitted light and the amount of reflected light.

[0041] Moreover, since the wavelength centroid has a correlation with the film thickness, it can be used for deriving the film thickness. Figure 5 is a diagram showing the relationship between wavelength and film thickness. In Figure 5 , the horizontal axis is set as the wavelength and the vertical axis is set as the reflectance. In the example shown in Figure 5 , the relationship between wavelength and reflectance is shown for each of the examples with a film thickness of 820 nm, 830 nm, and 840 nm. As Figure 5 shown, the wavelength centroid varies depending on the film thickness. Thus, since the wavelength centroid has a correlation with the film thickness, by determining the wavelength centroid, the film thickness can be estimated.

[0042] Return Figure 1The storage unit 33 stores information on the relationship between film thickness and the measurement parameter (here, the wavelength center of gravity). As mentioned above, film thickness and wavelength center of gravity are correlated. Therefore, by pre-preparing this information, the film thickness can be derived based on this information and the actually measured wavelength center of gravity. The storage unit 33 stores this information for each film type.

[0043] Relationship information can be derived based on the theoretical reflectivity corresponding to the film type and the overall spectral characteristics (spectral sensitivity) of the film thickness measurement device 1. Once the film type (refractive index and extinction coefficient) and film thickness are determined, the theoretical reflectivity value for each wavelength is determined. The overall spectral characteristics of the film thickness measurement device 1 can be predetermined (estimated) using various methods. The following describes an example method for estimating the overall spectral characteristics of the film thickness measurement device 1.

[0044] The spectral characteristics of the film thickness measurement device 1 can be estimated by, for example, integrating the spectral characteristics (spectral sensitivity) of each optical component of the film thickness measurement device 1. Specifically, the spectral characteristics of the film thickness measurement device 1 can be estimated by integrating the brightness spectrum of the light source 10, the spectral transmittance (transmittance spectrum) of the half mirror 11, the spectral transmittance (transmittance spectrum) of the field lens 12, the spectral transmittance (transmittance spectrum) of the lens 21, the spectral transmittance of the tilted dichroic mirror 22, the quantum efficiency (QE) or spectral sensitivity of the area sensor 23, the quantum efficiency (QE) or spectral sensitivity of the area sensor 24, and the reflectance of a bare wafer placed in place of the sample 100.

[0045] In this case, the spectral characteristic SCT_xm,yn(λ) on the transmission side of the tilted dichroic mirror 22 is expressed by the following equation (3). Furthermore, the spectral characteristic SCR_xm,yn(λ) on the reflection side of the tilted dichroic mirror 22 is expressed by the following equation (4). In equations (3) and (4), λ represents the wavelength, xm and yn represent the coordinates of the surface of the sample 100, SC1 represents the luminance spectrum of the light source 10, SC2 represents the spectral transmittance of the half mirror 11, SC3 represents the spectral transmittance of the field lens 12, SC4 represents the spectral transmittance of the lens 21, SC5 represents the spectral transmittance of the tilted dichroic mirror 22, SC6 represents the quantum efficiency or spectral sensitivity of the area sensor 23, SC7 represents the quantum efficiency or spectral sensitivity of the area sensor 24, and R represents the reflectivity of the bare wafer. SCT_xm,yn(λ)=SC1(λ)xm,yn×SC2(λ)xm,yn×SC3(λ)xm,yn×SC4(λ)xm,yn×SC5(λ)xm,yn×SC6(λ)xm,yn×R(λ)(3) SCR_xm,yn(λ)=SC1(λ)xm,yn×SC2(λ)xm,yn×SC3(λ)xm,yn×SC4(λ)xm,yn×SC5(λ)xm,yn×SC7(λ)xm,yn×R(λ)(4)

[0046] In addition, when the spatial uniformity of the spectral characteristics on the surface of sample 100 is high (the deviation of the spectral characteristics of each coordinate is small), the position dependence of each coordinate can be ignored, for example, it can be set to SC1(λ)xm,yn=SC1(λ) (the same applies to SC2 to SC7).

[0047] The spectral characteristics of the film-thickness measurement device 1 can be roughly estimated using, for example, various band-pass filters. Figure 6 1 is a diagram schematically showing an example of a configuration for performing an approximate calculation of spectral characteristics of the film thickness measuring device 1. Figure 6 In addition to the various components included in the film thickness measurement apparatus 1 described above, various bandpass filters 51 to 54 are also shown. For example, if the rate of change of the spectrum is a continuous, monotonic characteristic, the spectral characteristics SCT_xm,yn(λ) on the transmission side and SCR_xm,yn(λ) on the reflection side of the film thickness measurement apparatus 1 can be estimated simultaneously for each coordinate of the sample 100 while sequentially switching between the various bandpass filters 51 to 54. In this case, the spectral characteristics SCT_xm,yn(λ) on the transmission side are estimated based on the amount of transmitted light measured by the area sensor 23, while the spectral characteristics SCR_xm,yn(λ) on the reflection side are estimated based on the amount of reflected light measured by the area sensor 24, without considering the spectral characteristics of the various optical components that constitute the film thickness measurement apparatus 1 individually. Furthermore, when performing the estimated spectral characteristics of this configuration, a bare wafer 500 is placed in place of the sample 100.

[0048] exist Figure 6 In the illustrated configuration, bandpass filters 51 to 54 are filters that remove light in wavelength bands outside of a predetermined wavelength band. Bandpass filter 51 is a filter that removes light in wavelength bands outside of the first wavelength region, for example, the lowest wavelength. Bandpass filter 52 is a filter that removes light in wavelength bands outside of the second wavelength region, which is higher than the first wavelength region. Bandpass filter 53 is a filter that removes light in wavelength bands outside of the third wavelength region, which is higher than the second wavelength region. Bandpass filter 54 is a filter that removes light in wavelength bands outside of the fourth wavelength region, which is higher than the third wavelength region.

[0049] Figure 7 Is explained through Figure 6 An example of a method for estimating spectral characteristics of the structure shown in FIG. Figure 7In FIG, the image of one coordinate included in the bare wafer 500 is shown on the left, the amount of transmitted light measured by the area sensor 23 with respect to the above one coordinate while switching the bandpass filters 51 to 54 is shown on the upper right, and the amount of reflected light measured by the area sensor 24 with respect to the above one coordinate while switching the bandpass filters 51 to 54 is shown on the lower right. Figure 7 In the upper right and lower right figures, the horizontal axis is wavelength and the vertical axis is spectral intensity.

[0050] exist Figure 7 In the upper right figure, the wavelength region corresponding to the first wavelength region of the band-pass filter 51 is wavelength region 151, the wavelength region corresponding to the second wavelength region of the band-pass filter 52 is wavelength region 152, the wavelength region corresponding to the third wavelength region of the band-pass filter 53 is wavelength region 153, and the wavelength region corresponding to the fourth wavelength region of the band-pass filter 54 is wavelength region 154. Figure 7 As shown in the upper right figure of FIG, the amount of light transmitted when each bandpass filter 51 to 54 is used, and by performing curve fitting on this data, for example, a curve 160 representing the relationship between wavelength and spectral intensity is derived. The relational expression (polynomial) representing such curve 160 represents the spectral characteristic SCT_xm,yn(λ) on the transmission side. Examples of curve fitting methods include polynomial approximation and other curve fitting methods. In addition to curve fitting, interpolation methods and other methods can also be used to derive a curve representing the relationship between wavelength and spectral intensity.

[0051] Likewise, in Figure 7 In the lower right figure, the wavelength region corresponding to the first wavelength region of the band-pass filter 51 is wavelength region 251, the wavelength region corresponding to the second wavelength region of the band-pass filter 52 is wavelength region 252, the wavelength region corresponding to the third wavelength region of the band-pass filter 53 is wavelength region 253, and the wavelength region corresponding to the fourth wavelength region of the band-pass filter 54 is wavelength region 254. Figure 7 As shown in the lower right figure of , by determining the amount of transmitted light when using each bandpass filter 51 to 54 and performing curve fitting on the data of the transmitted light amount, a curve 260 representing the relationship between wavelength and spectral intensity is derived. The relationship expression (polynomial) representing such a curve 260 is the relationship expression representing the spectral characteristic SCR_xm,yn(λ) on the reflection side. In addition, as a method of curve fitting, there are, for example, polynomial approximation and other curve fitting methods. In addition to curve fitting, interpolation methods can also be used to derive a curve representing the relationship between wavelength and spectral intensity. As described above, the bandpass filters 51 to 54 can be used to implement an approximate calculation of the spectral characteristics of the film thickness measurement device 1.

[0052] The spectral characteristics of the film-thickness measurement device 1 can be roughly estimated using, for example, a spectrometer. Figure 8 1 is a diagram schematically showing an example of another configuration for performing an approximate calculation of the spectral characteristics of the film thickness measuring device 1. Figure 8 2 shows a configuration in which spectrometers 60 and 70 are provided instead of the area sensors 23 and 24 of the above-mentioned film thickness measuring apparatus 1 .

[0053] The spectrometer 60 derives the spectral characteristic SC8(λ)xm,yn, which is the cumulative spectral characteristic of each optical component other than the area sensor 23's quantum efficiency or spectral sensitivity (SC6(λ)xm,yn), from the transmission-side spectral characteristic SCT_xm,yn(λ). The spectrometer 60 includes a measuring unit 61 and a probe 62. The spectrometer 60 separates the light input from the probe 62 (light transmitted through the tilted dichroic mirror 22) for each wavelength, and the measuring unit 61 derives the intensity of each wavelength. In this way, the spectral characteristic SC8(λ)xm,yn is derived. The transmission-side spectral characteristic SCT_xm,yn(λ) is expressed as the product of the area sensor 23's quantum efficiency or spectral sensitivity (SC6(λ)xm,yn) and the cumulative spectral characteristic SC8(λ)xm,yn, as shown in the following equation (5). SCT_xm,yn(λ)=SC6(λ)xm,yn×SC8(λ)xm,yn (5)

[0054] Similarly, within the reflection-side spectral characteristic SCR_xm,yn(λ), the spectrometer 70 can derive the spectral characteristic SC9(λ)xm,yn, which is the cumulative spectral characteristic of each optical component other than the area sensor 24's quantum efficiency or spectral sensitivity (SC7(λ)xm,yn). The spectrometer 70 includes a measuring unit 71 and a probe 72. The spectrometer 70 separates the light input from the probe 72 (light reflected by the tilted dichroic mirror 22) for each wavelength, and the measuring unit 71 derives the intensity of each wavelength. In this way, the aforementioned spectral characteristic SC9(λ)xm,yn is derived. The reflection-side spectral characteristic SCR_xm,yn(λ) is expressed as the product of the area sensor 24's quantum efficiency or spectral sensitivity (SC7(λ)xm,yn) and the cumulative spectral characteristic SC9(λ)xm,yn, which is the cumulative spectral characteristic of each optical component, as shown in the following equation (6). SCR_xm,yn(λ)=SC7(λ)xm,yn×SC9(λ)xm,yn (6)

[0055] Furthermore, while the above descriptions describe multiple examples of using the film thickness measurement device 1 to perform an approximate calculation of the spectral characteristics of the film thickness measurement device 1, the approximate calculation of the spectral characteristics of the film thickness measurement device 1 does not necessarily have to be performed using the film thickness measurement device 1. Specifically, as long as the aforementioned relationship information is stored in the storage unit 33, the spectral characteristics of the film thickness measurement device 1 used to derive the relationship information may be obtained in any manner.

[0056] As described above, the relationship information between the film thickness and the wavelength center of gravity is derived based on the theoretical reflectivity corresponding to the type of film and the spectral characteristics of the film thickness measuring device 1. Specifically, the relationship information is derived by deriving the expected value of the wavelength center of gravity (measurement parameter) based on the theoretical reflectivity and the spectral characteristics of the film thickness measuring device 1 (see Figure 9 ), and the relationship is derived by plotting the expected value of the wavelength center of gravity and curve fitting (refer to Figure 10 Hereinafter, an example of deriving information on the relationship between the film thickness and the wavelength center of gravity of a certain film type will be described.

[0057] Figure 9 This figure illustrates the derivation of expected values ​​for the wavelength center of gravity of measurement parameters. Currently, since the film type is fixed, the theoretical reflectance value for each wavelength is determined according to the film thickness. Assuming a certain film thickness is specified, the theoretical reflectance R' value for each wavelength is determined. In this case, the expected value of the amount of transmitted light IT' measured by the area sensor 23 can be estimated based on the theoretical reflectance R' for each wavelength and the spectral characteristics SCT_xm,yn(λ) of the transmission side of the film thickness measurement device 1 for each wavelength. Since the area sensor 23 does not have a spectroscopic function, the expected value of the amount of transmitted light IT' measured by the area sensor 23 is the value obtained by integrating the intensity of light for each wavelength. Similarly, the expected value of the amount of reflected light IR' measured by the area sensor 24 can be estimated based on the theoretical reflectance R' for each wavelength and the spectral characteristics SCR_xm,yn(λ) of the reflection side of the film thickness measurement device 1 for each wavelength. Furthermore, according to equation (1) or (2) above, the expected value of the wavelength center of gravity x' can be derived from the expected value of the transmitted light quantity IT' and the expected value of the reflected light quantity IR'. In this way, the expected value of the wavelength center of gravity x' for a certain film thickness can be derived when the film type is fixed. Furthermore, for the same film type, the expected value of the wavelength center of gravity x' for each film thickness can be derived while varying the film thickness conditions. This allows the expected value of the wavelength center of gravity x' for each of the multiple film thickness conditions to be derived for a given film type.

[0058] Figure 10 This is a diagram explaining the derivation of a relational expression by curve fitting. Currently, for a certain type of film, the expected value of the wavelength center of gravity x' is derived for each of a plurality of film thickness conditions. For example, Figure 10In the example shown, the expected values ​​of the wavelength center of gravity x' of each of the three pattern film thicknesses (film thickness d = 90nm, 100nm, 110nm) are plotted on a plotting diagram with the horizontal axis: wavelength center of gravity x' and the vertical axis: film thickness d. In practice, the expected values ​​of the wavelength center of gravity x' with more film thickness conditions are plotted. Moreover, by performing curve fitting on the plotted data, a curve 360 ​​representing the relationship between the film thickness d and the wavelength center of gravity x' is derived. The relationship expression representing such a curve 360 ​​is the relationship expression between the film thickness and the measurement parameters. The relationship expression between the film thickness and the measurement parameters is expressed as a polynomial, such as the following formula (7). By obtaining the parameters (a, b, c, ...) of the polynomial, the state of the film thickness d can be derived if the wavelength center of gravity x' is input. dxm,yn(x′)=axm,yn+bxm,ynx′+cxm,ynx′2+… (7)

[0059] return Figure 1 The storage unit 33 stores the relationship between film thickness and wavelength center of gravity, as shown in equation (7) above, as the aforementioned relationship information. In this case, the relationship information is a relationship between film thickness and wavelength center of gravity derived by plotting and fitting the expected values ​​of wavelength center of gravity corresponding to each film thickness, derived based on the theoretical reflectivity and the spectral characteristics of the film thickness measuring device 1. The storage unit 33 stores such a relationship for each type of film.

[0060] The analyzing unit 32 derives the film thickness of the sample 100 based on the relational expression between the film thickness and the wavelength centroid stored as relational information in the storage unit 33 and the wavelength centroid of the measurement parameters related to the sample 100 obtained by the computing unit 31. The analyzing unit 32 derives the film thickness of the sample 100 based on the relational expression corresponding to the type of the film of the sample 100 and the wavelength centroid obtained by the computing unit 31 (analyzing step). That is, the analyzing unit 32 reads the relational expression corresponding to the type of the film of the sample 100 from the storage unit 33 (reading step) and inputs the wavelength centroid obtained by the computing unit 31 into the wavelength centroid x′ of the relational expression shown in Formula (7), thereby deriving the film thickness d of the sample 100.

[0061] Figure 11 This figure explains how to derive the film thickness using a relational expression. Figure 11 As shown, when the curve 360 ​​showing the relationship between the film thickness d and the wavelength centroid x′ is derived and the above-mentioned formula (7) is derived, the value of the film thickness d can be uniquely derived from the value of the wavelength centroid x′ obtained by the calculation unit 31.

[0062] Furthermore, as described above, the measurement parameters may be various parameters having a correlation with the film thickness other than the wavelength center of gravity x′. Figure 12 (a) to (c) are diagrams explaining the derivation of relational expressions for measurement parameters other than the wavelength center of gravity.

[0063] Figure 12 (a) is a diagram illustrating the derivation of a relational expression when the ratio (ratio) of the amount of transmitted light IT' measured by area sensor 23 to the amount of reflected light IR' measured by area sensor 24 is used as a measurement parameter. The expected value x" of the ratio is derived using the following equation (8). x″=IT′ / IR′ (8) Under the same film type, while changing the film thickness conditions, the expected values ​​x″ of multiple ratios are derived. By plotting the expected values ​​x″ of each ratio and performing curve fitting, a curve 460 representing the relationship between the film thickness d and the ratio x″ is derived, and the relationship expression represented by the following formula (9) representing the curve 460 is derived. dxm,yn(x″)=axm,yn+bxm,ynx″+cxm,ynx″2+·· (9)

[0064] Similarly, when the amount of transmitted light IT' is set as the measurement parameter, under the same film type, a plurality of expected values ​​x'' of the amount of transmitted light IT' are derived while changing the film thickness condition. By plotting the expected values ​​x'' of the amount of transmitted light IT' and performing curve fitting, a curve 560 showing the relationship between the film thickness d and the amount of transmitted light x'' is derived (see Figure 12 (b)), the relationship expression represented by the following equation (10) is derived to represent the curve 560. dxm,yn(x″′)=axm,yn+bxm,ynx″′+cxm,ynx″′2+·· (10)

[0065] Similarly, when the reflected light amount IR′ is set as the measurement parameter, under the same film type, a plurality of expected values ​​x″″ of the reflected light amount IR′ are derived while changing the film thickness condition. By plotting the expected values ​​x″″ of the reflected light amount IR′ and performing curve fitting, a curve 660 representing the relationship between the film thickness d and the reflected light amount x″″ is derived (see Figure 12 (c)), the relationship expression represented by the following equation (11) is derived to represent the curve 660. dxm,yn(x″″)=axm,yn+bxm,ynx″″+cxm,ynx″″2+·· (11)

[0066] Next, the effects of the film thickness measurement device 1 according to this embodiment will be described.

[0067] The film thickness measurement device 1 of this embodiment measures the film thickness of a sample 100 having a film 100b formed on a substrate 100a. The device comprises: a light source 10 for irradiating the sample 100 with light in a planar manner; area sensors 23 and 24 for capturing light from the sample 100; a calculation unit 31 for deriving measurement parameters related to the sample 100 based on signals from the area sensors 23 and 24; a storage unit 33 for storing relationship information between the film thickness and the measurement parameters; and an analysis unit 32 for deriving the film thickness of the sample 100 based on the relationship information and the measurement parameters related to the sample 100 obtained by the calculation unit 31. The relationship information is derived based on a theoretical reflectance corresponding to the type of film and the spectral characteristics of the film thickness measurement device 1 as a whole.

[0068] The film thickness measurement device 1 of this embodiment stores relationship information between film thickness and measurement parameters. Furthermore, the film thickness measurement device 1 derives measurement parameters based on signals from area sensors 23 and 24 that capture light from the sample 100, and derives the film thickness of the sample 100 based on these measurement parameters and the relationship information. Here, the relationship information is derived based on the theoretical reflectivity corresponding to the film type and the spectral characteristics of the film thickness measurement device 1 as a whole. This information precisely defines the correlation between the film thickness and the measurement parameters under specific conditions for the film type. Therefore, by deriving the film thickness of the sample 100 based on the measurement parameters derived from the imaging results and the relationship information, the film thickness of the sample 100 can be derived with high accuracy. Furthermore, since the film thickness measurement device 1 of this embodiment uses pre-acquired relationship information (information derived from the theoretical reflectivity and spectral characteristics) to derive the film thickness of the sample 100, it is unnecessary to perform measurements on a reference sample to determine the relationship between the film thickness and the measurement parameters, allowing for simple film thickness measurement of the sample 100.

[0069] The storage unit 33 stores relationship information for each type of film, and the analysis unit 32 can derive the film thickness of the sample 100 based on the relationship information corresponding to the type of film of the sample 100 and the measurement parameters related to the sample 100 obtained by the calculation unit 31. In this way, by storing relationship information for each type of film and deriving the film thickness of the sample 100 based on the relationship information corresponding to the type of film of the sample 100 and the measurement parameters, it is possible to perform film thickness measurement of samples 100 of various film types with high accuracy and simplicity.

[0070] The film thickness measurement device 1 further includes a tilted dichroic mirror 22, whose transmittance and reflectance vary according to wavelength within a predetermined wavelength band, and separates light from the sample 100 by transmission and reflection. Furthermore, an area sensor 24 captures the light reflected by the tilted dichroic mirror 22 and outputs a first signal. Separately, an area sensor 23 captures the light transmitted through the tilted dichroic mirror 22 and outputs a second signal. In this manner, the tilted dichroic mirror 22, whose transmittance and reflectance vary according to wavelength, separates the light from the sample 100. By capturing the separated light beams using the area sensors 23 and 24, the ratio of transmitted light to the ratio of reflected light can be appropriately detected, and information indicating wavelength can be determined from the detected information. By thus configuring the device to be able to determine information indicating a wavelength that is highly correlated with film thickness, the accuracy of film thickness measurement can be improved.

[0071] The calculation unit 31 can derive the wavelength center of gravity based on the first signal and the second signal as a measurement parameter. This allows the wavelength center of gravity, which has a high correlation with the film thickness, to be used as the measurement parameter, thereby improving the accuracy of film thickness measurement.

[0072] The relationship information can be a relationship equation between film thickness and measurement parameters derived by plotting and fitting the expected values ​​of the measurement parameters corresponding to each film thickness, derived based on theoretical reflectivity and spectral characteristics. Using this relationship equation as the relationship information allows the film thickness of sample 100 to be derived with high accuracy based on the relationship information that precisely defines the correlation between film thickness and measurement parameters.

[0073] While the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments. For example, in the film thickness measurement device 1 of the above embodiment, the area sensors 23 and 24 are used to capture light transmitted through and reflected from the tilted dichroic mirror 22, thereby deriving measurement parameters and, in turn, the film thickness. The present disclosure is not limited to this embodiment; for example, a film thickness measurement device that does not include the tilted dichroic mirror 22 can be used to measure the film thickness of an object.

[0074] Figure 13 Schematic diagram of a film thickness measuring device 1B according to a modified example. Figure 13 The control device 30 (calculation unit, storage unit, analysis unit) is omitted in the figure. Figure 13As shown, the film thickness measuring device 1B has a camera system 20B, which replaces the camera system 20 of the film thickness measuring device 1. The camera system 20B does not have a tilted dichroic mirror and has only one area sensor. That is, the camera system 20B has a lens 21 and one area sensor 23B. In such a configuration, the amount of light (the intensity of light from the sample 100) can be measured in the area sensor 23B. Therefore, for example, by pre-storing a relational expression representing the relationship between such an amount of light and the film thickness as the above-mentioned relational information, the film thickness can be derived based on the relational expression and the measured amount of light. In this case, the relational expression (relational information) is also derived based on the theoretical reflectivity corresponding to the type of film and the spectral characteristics of the film thickness measuring device 1B as a whole.

[0075] In addition, in the above embodiment, an example of measuring the film thickness of the sample 100 in which only one film 100b is formed on the surface of the substrate 100a is described, but it is not limited to this. The film thickness of a sample with a multilayer film structure in which more than two layers of films are formed on the surface of the substrate can be measured.

[0076] Figure 14 : is a cross-sectional view schematically showing a sample of a multilayer film structure of a variation. Figure 14 As shown, sample 200 includes substrate 200a, film 200b (first film), and film 200c (second film). Film 200b is laminated on the first layer of substrate 200a. Furthermore, film 200c is laminated on the second layer of film 200b. Here, the description assumes that film 200b is a silicon dioxide (SiO2) film and film 200c is a silicon nitride (SiN) film, but the film types are not limited to these.

[0077] The following describes how Figure 14 An example of the film thickness measurement procedure for a multilayer film structure sample 200 is shown. This film thickness measurement includes: a first layer extraction step, a second layer film formation step, a wavelength center of gravity extraction step after the second layer is formed, and a second layer extraction step. These steps are performed sequentially.

[0078] In the first layer extraction step, a sample having only the first layer, i.e., film 200b, formed thereon is prepared, and the film thickness of the sample (i.e., film 200b thickness measurement) and evaluation are performed. The film thickness extraction of only the first layer can be performed using the method described in the above embodiment. Figure 15 (a) is a diagram showing the distribution of the wavelength center of gravity measured for the first layer, Figure 15 (b) is about Figure 15 Graph showing the distribution of the film thickness of the first layer derived from the wavelength center of gravity shown in (a). In this way, when the distribution of the wavelength center of gravity of the first layer is derived by the method described in the embodiment, the distribution of the film thickness of the first layer can be derived.

[0079] The second layer film forming process is performed sequentially to the first layer lead-out process. In the second layer film forming process, the second layer, that is, the film 200c, is formed in a manner of being stacked on the film 200b. Figure 14 The sample shown is 200 complete.

[0080] The wavelength center of gravity derivation step after the second layer is formed is performed subsequent to the second layer forming step. In the wavelength center of gravity derivation step after the second layer is formed, the wavelength center of gravity after the second layer is formed is derived based on the imaging results of the light from the sample 200, similar to the wavelength center of gravity derivation in the above-mentioned embodiment. Figure 16 This is a diagram showing the distribution of wavelength centers of gravity measured after the second layer is formed.

[0081] The second layer derivation step is performed subsequent to the wavelength center of gravity derivation step after the second layer is formed. Figure 17 This figure explains how to derive the thickness of the second layer based on the wavelength center measured after the second layer is formed and the thickness of the first layer. Figure 17 As shown, in the second layer derivation process, the film thickness of the second layer is derived based on the wavelength center of gravity of the second layer after film formation measured (derived) in the wavelength center of gravity derivation process after film formation of the second layer, and the film thickness of the first layer measured (derived) in the first layer derivation process.

[0082] As a prerequisite for executing the second layer derivation step, the storage unit 33 stores information on the relationship between the second layer's film thickness and the wavelength center (measurement parameter) for each combination of the first layer's film type and film thickness, and the second layer's film type. Figure 18 This figure explains the relationship between the second layer thickness and the wavelength center of gravity for each first layer thickness. Figure 18 The "SiO2 film thickness" in the figure indicates the thickness of the first layer. Figure 18 As shown in FIG, the relationship between the film thickness of the second layer and the wavelength center varies depending on the film thickness of the first layer. Therefore, by storing information on the relationship between the film thickness of the second layer and the wavelength center for each combination of the type and thickness of the film of the first layer and the type of the film of the second layer (refer to FIG. Figure 18 ), the film thickness of the first layer can be measured with high precision.

[0083] The analysis unit 32 derives the film thickness of the film 200c of the sample 200 based on the relationship information corresponding to the combination of the film type and film thickness of the film 200b of the sample 200 and the film type of the film 200c, and the wavelength center of gravity related to the sample 200 obtained by the calculation unit 31.

[0084] In this way, by specifying the relationship information between the film thickness of the second layer and the measurement parameters for each combination of the type and film thickness of the first layer and the type of film of the second layer, when the type and film thickness of the first layer, i.e., film 200b, and the type and wavelength center of gravity of the second layer, i.e., film 200c, are known, the film thickness measurement of film 200c can be performed with high precision and simplicity.

[0085] Finally, various exemplary embodiments included in the present disclosure are described in the following [E1] to [E7].

[0086] [E1] A film thickness measuring device is provided for measuring the film thickness of an object having a film formed on a substrate, comprising: a light irradiation unit for irradiating light planarly toward the object; an imaging unit configured to capture light from the object; a calculation unit that derives a measurement parameter related to the object based on a signal from the imaging unit that has captured the light; a storage unit storing information on a relationship between film thickness and measurement parameters; and an analyzing unit for deriving a film thickness of the object based on the relationship information and the measurement parameter related to the object obtained by the calculating unit, The relationship information is derived based on a theoretical reflectance corresponding to the type of film and spectral characteristics of the film thickness measuring device.

[0087] [E2] The film thickness measuring device according to [E1], wherein The storage unit stores the relationship information for each type of film. The analyzing unit derives the film thickness of the object based on the relationship information corresponding to the type of the film of the object and the measurement parameter related to the object obtained by the calculating unit.

[0088] [E3] The film thickness measuring device according to [E1] or [E2] further comprises an optical element whose transmittance and reflectance vary according to wavelength in a predetermined wavelength band and separates light from the object by transmission and reflection. The imaging unit includes a first camera that captures light reflected by the optical element and outputs a first signal, and a second camera that captures light transmitted through the optical element and outputs a second signal.

[0089] [E4] The film thickness measuring device as described in [E3], wherein The calculation unit derives a wavelength centroid as the measurement parameter based on the first signal and the second signal.

[0090] [E5] The film thickness measuring device according to any one of [E1] to [E4], wherein The relationship information is a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting the expected values ​​of the measurement parameter corresponding to each film thickness derived based on the theoretical reflectance and the spectral characteristics.

[0091] [E6] The film thickness measuring device according to any one of [E1] to [E5], wherein The object is formed with a first film being a first layer stacked on the substrate and a second film being a second layer stacked on the first layer, as the films. The storage unit stores the relationship information between the film thickness of the second layer and the measurement parameter for each combination of the type and film thickness of the first layer and the type of the film of the second layer; The analysis unit derives the film thickness of the second film of the object based on the relationship information corresponding to the combination of the type and film thickness of the first layer corresponding to the first film of the object and the type of film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained by the calculation unit.

[0092] [E7] A film thickness measuring method is a method for measuring the thickness of a film of an object having a film formed on a substrate, performed by a film thickness measuring apparatus, comprising: a light irradiation step of irradiating the object with light in a planar manner; an imaging step of capturing light from the object; a calculation step of deriving a measurement parameter related to the object based on the signal of the light imaged in the imaging step; a reading step of reading the relationship information between the film thickness and the measurement parameter from a storage unit storing the relationship information; and an analyzing step of deriving a film thickness of the object based on the relationship information and the measurement parameters related to the object obtained in the calculating step, The relationship information is derived based on a theoretical reflectance corresponding to the type of film and spectral characteristics of the film thickness measuring device.

[0093] [E8] The film thickness measuring method as described in [E7], wherein The storage unit stores the relationship information for each type of film. In the analyzing step, the film thickness of the object is derived based on the relationship information corresponding to the type of the film of the object and the measurement parameter related to the object obtained in the calculating step.

[0094] [E9] The film thickness measuring method according to [E7] or [E8], wherein: In the imaging step, the following steps are performed: capturing light reflected by an optical element with a first camera and outputting a first signal, wherein the transmittance and reflectance of the optical element vary according to the wavelength in a predetermined wavelength band, and the light from the object is separated by transmission and reflection; and capturing light passing through the optical element with a second camera and outputting a second signal.

[0095] [E10] The film thickness measuring method as described in [E9], wherein In the calculation step, a wavelength centroid is derived as the measurement parameter based on the first signal and the second signal.

[0096] [E11] The film thickness measurement method according to any one of [E7] to [E10], wherein The relationship information is a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting the expected values ​​of the measurement parameter corresponding to each film thickness derived based on the theoretical reflectance and the spectral characteristics.

[0097] [E12] The film thickness measurement method according to any one of [E7] to [E11], wherein The object is formed with a first film being a first layer stacked on the substrate and a second film being a second layer stacked on the first layer, as the films. The storage unit stores the relationship information between the film thickness of the second layer and the measurement parameter for each combination of the type and film thickness of the first layer and the type of the film of the second layer; In the analysis step, the film thickness of the second film of the object is derived based on the relationship information corresponding to the combination of the type and film thickness of the first layer corresponding to the first film of the object and the type of film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained in the calculation step. Explanation of symbols

[0098] 1, 1B...film thickness measuring device, 10...light source (light irradiation unit), 22...tilted dichroic mirror (optical element), 23...area sensor (second camera, imaging unit), 23B...area sensor (imaging unit), 24...area sensor (first camera, imaging unit), 31...calculation unit, 32...analysis unit, 33...storage unit, 100, 200...sample (object), 100a, 200a...substrate, 100b...film, 200b...film (first film), 200c...film (second film).

Claims

1. A film thickness measuring device, wherein: This is a film thickness measuring device for measuring the thickness of an object having a film formed on a substrate. have: a light irradiation unit for irradiating light planarly toward the object; an imaging unit configured to capture light from the object; a calculation unit that derives a measurement parameter related to the object based on a signal from the imaging unit that has captured the light; a storage unit storing information on a relationship between film thickness and measurement parameters; and an analyzing unit for deriving a film thickness of the object based on the relationship information and the measurement parameter related to the object obtained by the calculating unit, The relationship information is derived based on a theoretical reflectance corresponding to the type of film and spectral characteristics of the film thickness measuring device.

2. The film thickness measuring device according to claim 1, wherein The storage unit stores the relationship information for each type of film. The analyzing unit derives the film thickness of the object based on the relationship information corresponding to the type of the film of the object and the measurement parameter related to the object obtained by the calculating unit.

3. The film thickness measuring device according to claim 1 or 2, wherein: The device further comprises an optical element whose transmittance and reflectance vary according to wavelength in a predetermined wavelength band and which separates light from the object by transmission and reflection. The imaging unit includes a first camera that captures light reflected by the optical element and outputs a first signal, and a second camera that captures light transmitted through the optical element and outputs a second signal.

4. The film thickness measuring device according to claim 3, wherein: The calculation unit derives a wavelength centroid as the measurement parameter based on the first signal and the second signal.

5. The film thickness measuring device according to claim 1 or 2, wherein: The relationship information is a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting the expected values ​​of the measurement parameter corresponding to each film thickness derived based on the theoretical reflectance and the spectral characteristics.

6. The film thickness measuring device according to claim 2, wherein: The object is formed with a first film as a first layer stacked on the substrate and a second film as a second layer stacked on the first layer, wherein the films are The storage unit stores the relationship information between the film thickness of the second layer and the measurement parameter for each combination of the type and film thickness of the first layer and the type of the second layer. The analysis unit derives the film thickness of the second film of the object based on the relationship information corresponding to the combination of the type and film thickness of the first layer corresponding to the first film of the object and the type of film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained by the calculation unit.

7. A method for measuring film thickness, wherein: A film thickness measuring method is performed by a film thickness measuring device for measuring the film thickness of an object having a film formed on a substrate. have: a light irradiation step of irradiating the object with light in a planar manner; an imaging step of capturing light from the object; a calculation step of deriving a measurement parameter related to the object based on the signal of the light imaged in the imaging step; a reading step of reading the relationship information between the film thickness and the measurement parameter from a storage unit storing the relationship information; and an analyzing step of deriving a film thickness of the object based on the relationship information and the measurement parameters related to the object obtained in the calculating step, The relationship information is derived based on a theoretical reflectance corresponding to the type of film and spectral characteristics of the film thickness measuring device.

8. The film thickness measuring method according to claim 7, wherein: The storage unit stores the relationship information for each type of film. In the analyzing step, the film thickness of the object is derived based on the relationship information corresponding to the type of the film of the object and the measurement parameter related to the object obtained in the calculating step.

9. The film thickness measuring method according to claim 7 or 8, wherein: In the imaging step, the following steps are performed: capturing light reflected by an optical element by a first camera and outputting a first signal, wherein the transmittance and reflectance of the optical element vary according to the wavelength in a prescribed wavelength band, and the light from the object is separated by transmission and reflection; and capturing light passing through the optical element by a second camera and outputting a second signal.

10. The film thickness measuring method according to claim 9, wherein: In the calculation step, a wavelength centroid is derived as the measurement parameter based on the first signal and the second signal.

11. The film thickness measuring method according to claim 7 or 8, wherein: The relationship information is a relationship expression between the film thickness and the measurement parameter derived by plotting and fitting the expected values ​​of the measurement parameter corresponding to each film thickness derived based on the theoretical reflectance and the spectral characteristics.

12. The film thickness measuring method according to claim 8, wherein: The object is formed with a first film as a first layer stacked on the substrate and a second film as a second layer stacked on the first layer, wherein the films are The storage unit stores the relationship information between the film thickness of the second layer and the measurement parameter for each combination of the type and film thickness of the first layer and the type of the second layer. In the analysis step, the film thickness of the second film of the object is derived based on the relationship information corresponding to the combination of the type and film thickness of the first layer corresponding to the first film of the object and the type of film of the second layer corresponding to the second film, and the measurement parameters related to the object obtained in the calculation step.

Images