Film thickness measurement device and film thickness measurement method

Abstract

To provide a film thickness measurement device and a film thickness measurement method that can measure a film thickness at high speed.SOLUTION: A film thickness measurement device 1 comprises: a light source 10 (light irradiation unit) that planarly irradiates a sample 100 (object) with light; a tilted dichroic mirror 22 (optical element) that has transmittance and reflectance changing according to a wavelength in a predetermined wavelength region, and transmits and reflects light from the object to separate the light; area sensors 23, 24 (imaging units) that pick up an image of the light separated by the optical element; and a controller 30 (analysis unit) that estimates the film thickness of the object on the basis of signals from the imaging units that pick up the images of light. The light irradiation unit irradiates the object with light with a wavelength included in the predetermined wavelength region of the optical element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to a film thickness measurement apparatus and a film thickness measurement method. [Background technology]

[0002] For example, in semiconductor manufacturing equipment, it is important to form a film uniformly on the wafer surface. Poor in-plane film thickness uniformity can lead to wiring defects, voids, and other failure factors, resulting in a decrease in yield. In this case, the increase in process time and material consumption leads to a decrease in productivity. For this reason, semiconductor manufacturing equipment typically measures film thickness using a point sensor or line scan (see, for example, Patent Document 1) to determine whether the desired film thickness distribution is achieved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-205132 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the method of measuring the film thickness using the point sensor or line scan described above has the problem of taking a long time to measure.

[0005] One aspect of the present invention has been made in view of the above circumstances, and has an object to provide a film thickness measurement device and a film thickness measurement method that are capable of measuring film thickness at high speed. [Means for solving the problem]

[0006] A film thickness measuring device according to one aspect of the present invention includes a light irradiation unit that irradiates a surface of an object with light, an optical element whose transmittance and reflectance change depending on the wavelength in a predetermined wavelength range and that separates the light from the object by transmitting and reflecting it, an imaging unit that images the light separated by the optical element, and an analysis unit that estimates the film thickness of the object based on a signal from the imaging unit that has imaged the light, wherein the light irradiation unit irradiates light of a wavelength included in the predetermined wavelength range of the optical element.

[0007] In a film thickness measurement device according to one aspect of the present invention, a surface of an object is irradiated with light having a wavelength within a predetermined wavelength range of an optical element. In this film thickness measurement device, the optical element separates the light from the object by transmitting and reflecting it. Here, the transmittance and reflectance of the optical element vary depending on the wavelength within the predetermined wavelength range. Therefore, the proportion of transmitted light and the proportion of reflected light in the light separated by the optical element vary depending on the wavelength. The separated light is then imaged by an imaging unit, thereby determining the proportion of transmitted light and the proportion of reflected light, and thus the wavelength. Furthermore, the analysis unit estimates the film thickness of the object based on a signal from the imaging unit. While the film thickness can be estimated based on information indicating the wavelength, as described above, the wavelength is determined from the imaging results of the imaging unit. Therefore, by taking into account the signal (signal from the imaging unit) containing information about the wavelength, the film thickness of the object can be estimated with high accuracy. In this film thickness measurement device, the object is irradiated with light in a planar manner, and the film thickness within the object's surface is simultaneously estimated in accordance with the light from the object, so the film thickness distribution within the surface can be estimated more quickly than when the film thickness within the surface is estimated while changing the light irradiation range using a point sensor, line scan, etc. As described above, the film thickness measurement device according to one aspect of the present invention can measure the film thickness of an object at high speed.

[0008] In the film thickness measuring device, the analysis unit may estimate the film thickness corresponding to each pixel based on wavelength information for each pixel in the imaging unit. With this configuration, it is possible to estimate the film thickness distribution on the irradiation surface of the object in more detail (for each pixel).

[0009] In the film thickness measurement device, the analysis unit may estimate the film thickness by further considering the angle of the light irradiated onto the object. Since the optical path changes when the angle of the light irradiated onto the object changes, it may not be possible to estimate the film thickness with high accuracy from information on the wavelength alone. In this regard, by further considering the angle of the light irradiated onto the object, the film thickness can be estimated with higher accuracy according to the actual optical path.

[0010] In the film thickness measuring device, the light irradiating section may irradiate the object with diffused light, thereby enabling the surface of the object to be uniformly irradiated with light.

[0011] In the film thickness measurement device, the light irradiating unit may have a light guide plate that generates diffused light, thereby enabling the surface of the object to be irradiated with light uniformly with a compact configuration.

[0012] The film thickness measurement device may further include a bandpass filter disposed between the optical element and the image capture unit, thereby removing light outside a desired wavelength range and improving the accuracy of film thickness estimation.

[0013] A film thickness measurement method according to one aspect of the present invention includes the following steps: a first step of irradiating a surface of an object with light; a second step of capturing an image of light separated by an optical element whose transmittance and reflectance change according to the wavelength in a predetermined wavelength range and separates the light from the object by transmitting and reflecting it; and a third step of deriving a wavelength based on the captured image and estimating a film thickness of the object based on the wavelength. This film thickness measurement method allows the film thickness of the object to be measured at high speed, similar to the film thickness measurement device described above. [Effects of the Invention]

[0014] According to an aspect of the present invention, a film thickness measurement device can measure the film thickness of an object at high speed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram schematically illustrating a film thickness measuring device according to an embodiment of the present invention. [Figure 2] 2A and 2B are diagrams showing an example of a light source, in which FIG. 2A shows a flat dome light and FIG. 2B shows a dome light. [Figure 3] 10A and 10B are diagrams illustrating the relationship between the characteristics of a dichroic mirror and the wavelength of light emitted from a light source. [Figure 4] 1A and 1B are diagrams illustrating the spectrum of light and the characteristics of an inclined dichroic mirror. [Figure 5] 10A and 10B are diagrams illustrating wavelength shifts according to the amount of transmitted light and the amount of reflected light. [Figure 6] FIG. 10 is a diagram showing the relationship between wavelength and film thickness. [Figure 7] FIG. 1 is a diagram illustrating the principle of film thickness measurement. [Figure 8] 1A and 1B are diagrams illustrating differences in the angle of incidence of light on a camera system. [Figure 9] FIG. 10 is a diagram illustrating correction of a film thickness measurement value. [Figure 10] 10A and 10B are diagrams showing the results of a comparison between the film thickness measurement device according to the present embodiment and a comparative example. [Figure 11] FIG. 10 is a diagram illustrating a film thickness measuring device according to a modified example. [Figure 12] FIG. 10 is a diagram illustrating a film thickness measuring device according to a modified example. [Figure 13] FIG. 10 is a diagram schematically illustrating a film thickness measuring device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0017] 1 is a schematic diagram showing a film thickness measurement apparatus 1 according to this embodiment. The film thickness measurement apparatus 1 is an apparatus that irradiates a sample 100 (object) with light in a planar manner and measures the thickness of a film formed on the sample 100 based on the light reflected from the sample 100. The sample 100 may be a light-emitting element such as an LED, mini LED, μLED, SLD element, laser element, vertical cavity surface laser element (VCSEL), or OLED, or may be a light-emitting element that adjusts the emission wavelength using a fluorescent substance containing nanodots or the like.

[0018] As shown in FIG. 1, the film thickness measuring device 1 includes a light source 10 (light irradiation unit), a camera system 20, and a control device 30 (analysis unit).

[0019] The light source 10 irradiates the sample 100 with light in a planar manner. The light source 10 irradiates, for example, substantially the entire surface of the sample 100 with light in a planar manner. The light source 10 is, for example, a light source that can uniformly irradiate the surface of the sample 100 and irradiates the sample 100 with diffused light. As shown in FIG. 2, the light source 10 may be a so-called flat dome-type light source 10A (see FIG. 2(a)) or a dome-type light source 10B (see FIG. 2(b)). The light source 10A shown in FIG. 2(a) includes an LED 10c and a light guide plate 10d. The light guide plate 10d generates diffused light in response to the light emitted from the LED 10c. The diffused light generated by the light guide plate 10d is reflected by the sample 100 and input to the camera system 20. Such a flat dome-type light source 10A can suppress glare while ensuring a sufficient field of view (for example, a field of view of about 300 mm). The light source 10B includes an LED 10e and a dome portion 10f. Light emitted from the LED 10e is irradiated onto the inner surface of the dome portion 10f, and the diffused light from the inner surface of the dome portion 10f is reflected by the sample 100. The reflected light from the sample 100 is input to the camera system 20. The light source 10 may be a surface illumination unit using a white LED, a halogen lamp, a Xe lamp, or the like.

[0020] The light source 10 irradiates the sample 100 with light having a wavelength included in a predetermined wavelength range of an inclined dichroic mirror 22 (described in detail below) included in the camera system 20. As described in detail below, the inclined dichroic mirror 22 is an optical element that separates light from the sample 100 by transmitting and reflecting it according to wavelength. The transmittance and reflectance of the inclined dichroic mirror 22 change according to wavelength within the above-mentioned predetermined wavelength range.

[0021] FIG. 3 is a diagram illustrating the relationship between the characteristics of the inclined dichroic mirror 22 and the wavelength of light emitted from the light source 10. In FIG. 3, the horizontal axis represents wavelength, and the vertical axis represents the transmittance of the inclined dichroic mirror 22. As shown by the characteristic X4 of the inclined dichroic mirror 22 in FIG. 3, the inclined dichroic mirror 22 exhibits a gradual change in light transmittance (and reflectance) with wavelength in a predetermined wavelength range X10, while maintaining a constant light transmittance (and reflectance) regardless of wavelength in wavelength ranges outside the predetermined wavelength range. As shown in FIG. 3, the light X20 output from the light source 10 includes light with wavelengths falling within the predetermined wavelength range X10. That is, the light source 10 outputs light with a broad spectrum that includes the predetermined wavelength range X10. The wavelength range (interference peak wavelength) involved in the measurement is determined by the material of the film formed on the sample 100 and the range of film thickness to be measured.

[0022] Returning to FIG. 1, the camera system 20 includes a lens 21, an inclined dichroic mirror 22 (optical element), area sensors 23 and 24 (imaging units), and band-pass filters 25 and 26.

[0023] The lens 21 is a lens that collects the incident light from the sample 100. The lens 21 may be arranged before (upstream of) the inclined dichroic mirror 22, or may be arranged in an area between the inclined dichroic mirror 22 and the area sensors 23, 24. The lens 21 may be a finite focus lens or an afocal lens. When the lens 21 is a finite focus lens, the distance from the lens 21 to the area sensors 23, 24 is set to a predetermined value. When the lens 21 is an afocal lens, the lens 21 is a collimator lens that converts the light from the sample 100 into parallel light, and is aberration-corrected so that parallel light can be obtained. The light output from the lens 21 is incident on the inclined dichroic mirror 22.

[0024] The inclined dichroic mirror 22 is a mirror made of a special optical material, and is an optical element that separates light from the sample 100 by transmitting and reflecting it according to the wavelength. The inclined dichroic mirror 22 is configured so that the transmittance and reflectance of light change according to the wavelength in a predetermined wavelength range.

[0025] FIG. 4 is a diagram illustrating the spectrum of light and the characteristics of inclined dichroic mirror 22. In FIG. 4, the horizontal axis represents wavelength, and the vertical axis represents spectral intensity (in the case of the spectrum of light) and transmittance (in the case of inclined dichroic mirror 22). As shown by characteristic X4 of inclined dichroic mirror 22 in FIG. 4, in inclined dichroic mirror 22, the transmittance (and reflectance) of light changes gradually with changes in wavelength in a predetermined wavelength range (the wavelength range from wavelength λ1 to λ2), while the transmittance (and reflectance) of light is constant regardless of changes in wavelength in wavelength ranges other than the predetermined wavelength range (i.e., wavelengths lower than wavelength λ1 and higher than wavelength λ2). In other words, in a specific wavelength range (the wavelength range from wavelength λ1 to λ2), the transmittance of light changes monotonically (reflectance monotonically decreases) with changes in wavelength. Since transmittance and reflectance have a negative correlation, i.e., when one increases, the other decreases, the other decreases. Therefore, hereinafter, the terms "transmittance (and reflectance)" may be used interchangeably. The phrase "constant light transmittance regardless of wavelength" does not only refer to a completely constant light transmittance, but also includes, for example, a case where the change in transmittance is 0.1% or less per 1 nm change in wavelength. On the wavelength side lower than wavelength λ1, the light transmittance is approximately 0% regardless of wavelength, and on the wavelength side higher than wavelength λ2, the light transmittance is approximately 100% regardless of wavelength. The phrase "light transmittance of approximately 0%" includes a transmittance of approximately 0% + 10%, and the phrase "light transmittance of approximately 100%" includes a transmittance of approximately 100% - 10%. In FIG. 4, waveform X1 indicates the waveform of light output from light source 10. As shown by waveform X1 in FIG. 4, the light output from light source 10 contains light of wavelengths included in the predetermined wavelength range of inclined dichroic mirror 22 (the wavelength range of wavelengths λ1 to λ2).

[0026] The area sensors 23 and 24 capture images of the light separated by the inclined dichroic mirror 22. The area sensor 23 captures images of the light transmitted by the inclined dichroic mirror 22. The area sensor 24 captures images of the light reflected by the inclined dichroic mirror 22. The wavelength range to which the area sensors 23 and 24 are sensitive corresponds to a predetermined wavelength range in which the transmittance (and reflectance) of light changes in accordance with changes in wavelength in the inclined dichroic mirror 22. 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.

[0027] Bandpass filter 25 is disposed between inclined dichroic mirror 22 and area sensor 23. Bandpass filter 26 is disposed between inclined dichroic mirror 22 and area sensor 24. Bandpass filters 25 and 26 may be, for example, filters that remove light in wavelength ranges other than the above-mentioned predetermined wavelength range (wavelength range in which the transmittance and reflectance of light change depending on the wavelength in inclined dichroic mirror 22).

[0028] Returning to Fig. 1, the control device 30 is a computer, and is physically configured to include memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The control device 30 functions by executing a program stored in the memory with the CPU of the computer system. The control device 30 may also be configured with a microcomputer or FPGA.

[0029] The control device 30 estimates the film thickness of the sample 100 based on the signals from the area sensors 23 and 24 that have imaged light. The control device 30 estimates the film thickness corresponding to each pixel based on the wavelength information for each pixel in the area sensors 23 and 24. More specifically, the control device 30 determines the amount of transmitted light specified based on the imaging result (signal from the area sensor 23) in the area sensor 23, the amount of reflected light specified based on the imaging result (signal from the area sensor 24) in the area sensor 24, the center wavelength of the tilted dichroic mirror 22 (the center wavelength of a predetermined wavelength range), and the width of the tilted dichroic mirror 22, and derives the wavelength centroid of the light for each pixel, and estimates the film thickness corresponding to each pixel based on the wavelength centroid. The width of the tilted dichroic mirror 22 is, for example, the wavelength width from the wavelength at which the transmittance becomes 0% to the wavelength at which the transmittance becomes 100% in the tilted dichroic mirror 22.

[0030] Specifically, the control device 30 derives the wavelength centroid of each pixel based on the following equation (1). In the following equation (1), λ represents the wavelength centroid, λ0 represents the center wavelength of the tilted dichroic mirror 22, A represents the width of the tilted dichroic mirror 22, R represents the amount of reflected light, and T represents the amount of transmitted light. λ = λ0 + A(T - R) / 2(T + R) (1)

[0031] FIG. 5 is a diagram for explaining the wavelength shift according to the amount of transmitted light and the amount of reflected light. When deriving λ (wavelength centroid) by the above-described equation (1), as shown in FIG. 5, for a pixel where T (amount of transmitted light) = R (amount of reflected light), λ = λ0 (the center wavelength of the tilted dichroic mirror 22). Also, for a pixel where T < R, that is, a pixel where the amount of reflected light is greater than the amount of transmitted light, λ = λ1 (a wavelength on the shorter wavelength side than λ0). Also, for a pixel where T > R, that is, a pixel where the amount of transmitted light is greater than the amount of reflected light, λ = λ2 (a wavelength on the longer wavelength side than λ0). Thus, the value of λ (wavelength centroid) shifts (wavelength shift) based on the amount of transmitted light and the amount of reflected light.

[0032] The method for deriving the wavelength centroid is not limited to the above. For example, since λ (wavelength centroid) is proportional to x below, the wavelength centroid may be derived from the following equations (2) and (3). In the following equation (3), IT indicates the amount of transmitted light, and IR indicates the amount of reflected light. Furthermore, when the spectral shape of the measurement target and the linear shape of the inclined dichroic mirror 22 are ideal, the parameters a and b in equation (2) can be determined by the optical characteristics of the inclined dichroic mirror 22. λ=ax+b (2) x = IT - IR / 2 (IT + IR) (3)

[0033] In reality, there are differences (individual differences) in the spectral characteristics between optical systems and cameras, so in order to correct for these, for example, the signal intensity of a substrate with known reflection characteristics can be used as a reference to derive x using the following equation (4): In the following equation (4), ITr represents the amount of transmitted light in the reference, and IRr represents the amount of reflected light in the reference. x=(IT / ITr-IR / IRr) / 2(IT / ITr+IR / IRr) (4)

[0034] Furthermore, in order to remove the influence of direct light from the light source, the signal amount in the non-reflecting state may be used to derive x using the following equation (5): In the following equation (5), ITb represents the amount of transmitted light in the non-reflecting state, and IRb represents the amount of reflected light in the non-reflecting state. x={(IT-ITb) / (ITr-ITb)-(IR-IRb) / (IRr-IRb)} / 2{(IT-ITb) / (ITr-ITb)+(IR-IRb) / (IRr-IRb)} (5)

[0035] Furthermore, in order to comprehensively perform various corrections such as film characteristics, irradiation spectrum, and nonlinearity of the inclined dichroic mirror 22, the wavelength centroid (λ) may be approximated by a polynomial such as the following equation (6): Note that the parameters (a, b, c, d, e) in the following equation (6) are determined, for example, by measuring multiple samples with different wavelength centroids (film thicknesses). λ=ax4+bx3+cx2+dx+e (6)

[0036] FIG. 6 is a diagram illustrating the principle of film thickness measurement. In FIG. 6, the horizontal axis represents wavelength and the vertical axis represents reflectance. In the example shown in FIG. 6, the relationship between wavelength and reflectance is shown for film thicknesses of 820 nm, 830 nm, and 840 nm. As shown in FIG. 6, the wavelength centroid differs depending on the film thickness. Therefore, by identifying the wavelength centroid, it is possible to estimate the film thickness.

[0037] The relationship between wavelength and film thickness can be explained by the following equation (7), as shown in Figure 7. In the following equation (7), n is the refractive index of the film, d is the film thickness, m is a positive integer (1, 2, 3, ...), and λ is the wavelength centroid. 2nd is the optical path difference (the optical path difference caused by the placement of the film). The control device 30 estimates the film thickness corresponding to each pixel from the wavelength centroid of each pixel based on the following equation (7). 2nd=mλ(m=1,2,3,…) (constructive condition) 2nd=(m-1 / 2)λ(m=1,2,3,…) (mutually destructive condition) (7)

[0038] Here, equation (7), which shows the relationship between wavelength and film thickness, holds when light is incident perpendicularly on sample 100. On the other hand, equation (7) does not hold when light is not incident perpendicularly on sample 100. That is, as shown in FIG. 8, when light is incident on sample 100 having film 101 disposed on the surface of substrate 102, the angle of incidence of light varies depending on the measurement point, resulting in different optical path differences, making it impossible to uniformly estimate the film thickness with high accuracy using equation (7). Therefore, in order to estimate the film thickness with high accuracy at any measurement point (angle of incidence), calculations (correction processing) according to the measurement point (angle of incidence) are required.

[0039] FIG. 9 is a diagram illustrating the correction of film thickness measurements. As shown in FIG. 9(a), when the incident angle of light is θ, the optical path difference is expressed as 2ndcosθ. As a result, the relationship between wavelength and film thickness taking into account the incident angle θ can be explained by the following equation (8), as shown in FIG. 9(b). The control device 30 estimates the film thickness according to the measurement point (incident angle) based on the following equation (8). In this way, the control device 30 may estimate the film thickness from the wavelength centroid, further taking into account the angle of light irradiated onto the sample 100. 2ndcosθ=mλ (constructive condition) 2ndcosθ=(m-1 / 2)λ (destructive condition) (8)

[0040] As described above, the film thickness measurement apparatus 1 performs a film thickness measurement method, which includes, for example, a first step of irradiating the sample 100 with light in a planar manner, a second step of capturing an image of light separated by the inclined dichroic mirror 22, which has a transmittance and reflectance that change depending on the wavelength in a predetermined wavelength range and separates the light from the sample 100 by transmitting and reflecting it, and a third step of deriving the wavelength based on the captured image and estimating the film thickness of the sample 100 based on the wavelength.

[0041] Next, the effects of this embodiment will be described.

[0042] The film thickness measuring device 1 of this embodiment includes a light source 10 that irradiates light onto the sample 100 in a planar manner, an inclined dichroic mirror 22 whose transmittance and reflectance change depending on the wavelength in a predetermined wavelength range and that separates the light from the sample 100 by transmitting and reflecting it, area sensors 23 and 24 that image the light separated by the inclined dichroic mirror 22, and a control device 30 that estimates the film thickness of the sample 100 based on signals from the area sensors 23 and 24 that have imaged the light, and the light source 10 irradiates light of a wavelength included in the predetermined wavelength range of the inclined dichroic mirror 22.

[0043] In the film thickness measurement apparatus 1 according to this embodiment, the sample 100 is irradiated with light of a wavelength within a predetermined wavelength range of the inclined dichroic mirror 22 in a planar manner. The inclined dichroic mirror 22 then separates the light from the sample 100 by transmitting and reflecting it. The transmittance and reflectance of the inclined dichroic mirror 22 vary depending on the wavelength within the predetermined wavelength range. Therefore, the proportions of transmitted light and reflected light in the light separated by the inclined dichroic mirror 22 vary depending on the wavelength. The separated light is then imaged by the area sensors 23 and 24, thereby determining the proportions of transmitted light and reflected light, and thus the wavelength. Furthermore, the control device 30 estimates the film thickness of the sample 100 based on signals from the area sensors 23 and 24. While the film thickness can be estimated based on information indicating the wavelength, as described above, the wavelength is identified from the imaging results of the area sensors 23 and 24. Therefore, by taking into consideration the signals containing the wavelength information (signals from the area sensors 23 and 24), the film thickness of the sample 100 can be estimated with high accuracy. In the film thickness measuring device 1 according to this embodiment, the sample 100 is irradiated with light in a planar manner, and the in-plane film thickness of the sample 100 is simultaneously estimated according to the light from the sample 100. Therefore, the in-plane film thickness distribution can be estimated more quickly than when the in-plane film thickness is estimated while changing the light irradiation range using a point sensor, line scan, or the like. As described above, the film thickness measuring device 1 according to this embodiment can measure the film thickness of the sample 100 at high speed.

[0044] FIG. 10 shows a comparison result between the film thickness measurement apparatus 1 according to the present embodiment and a comparative example. As shown in FIG. 10, when the film thickness is measured point by point using a point sensor, the measurement time is, for example, about four hours. Here, four hours refers to the measurement time when approximately 16,000 points are detected. Also, as shown in FIG. 10, when the film thickness is measured line by line using line scanning, the measurement time is, for example, about three minutes. In contrast, as shown in FIG. 10, in the film thickness measurement apparatus 1 according to the present embodiment, light is irradiated planarly onto the sample 100, and the film thickness within the surface is measured simultaneously, resulting in a measurement time of about five seconds. Thus, the film thickness measurement apparatus 1 according to the present embodiment can estimate the film thickness distribution within the surface more quickly than the point sensor or line scanning according to the comparative example. Note that the film thickness measurement apparatus 1 according to the present embodiment achieved an error between the measurement result and the actual film thickness of 0.1% or less. Thus, the film thickness measurement apparatus 1 according to the present embodiment can simultaneously achieve both a reduction in film thickness measurement time and an improvement in measurement accuracy. Furthermore, while configurations relating to point sensors and line scans are difficult to install in-line (mounted on an apparatus), the film thickness measuring apparatus 1 according to this embodiment can be easily adapted for in-line installation.

[0045] In the film thickness measuring device 1, the control device 30 may estimate the film thickness corresponding to each pixel based on wavelength information for each pixel in the area sensors 23 and 24. With this configuration, the film thickness distribution on the irradiation surface of the sample 100 can be estimated in more detail (for each pixel).

[0046] In the film thickness measurement apparatus 1, the control device 30 may estimate the film thickness by further considering the angle of the light irradiated onto the sample 100. Since the optical path changes when the angle of the light irradiated onto the sample 100 changes, there are cases where the film thickness cannot be estimated with high accuracy from information on the wavelength alone. In this regard, by further considering the angle of the light irradiated onto the sample 100, the film thickness can be estimated with higher accuracy according to the actual optical path. Specifically, the film thickness is estimated using the above-mentioned equation (8).

[0047] In the film thickness measuring device 1, the light source 10 may irradiate the sample 100 with diffused light. This allows the surface of the sample 100 to be irradiated with light uniformly.

[0048] In the film thickness measurement device 1, the light source 10 may have a light guide plate 10d (see FIG. 2(a)) that generates diffused light. This allows the surface of the sample 100 to be uniformly irradiated with light with a compact configuration.

[0049] The film thickness measurement device 1 may further include bandpass filters 25 and 26 disposed between the inclined dichroic mirror 22 and the area sensors 23 and 24. This makes it possible to remove light outside a desired wavelength range, thereby improving the accuracy of film thickness estimation.

[0050] The film thickness measurement method according to this embodiment is performed by film thickness measurement apparatus 1, and includes the following steps: a first step of irradiating light planarly onto sample 100; a second step of capturing an image of light separated by inclined dichroic mirror 22, which has transmittance and reflectance that change depending on the wavelength in a predetermined wavelength range and separates the light from sample 100 by transmitting and reflecting it; and a third step of deriving the wavelength based on the captured image and estimating the film thickness of sample 100 based on the wavelength. Such a film thickness measurement method allows the film thickness of sample 100 to be measured quickly.

[0051] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The film thickness measurement device 1 can be applied to measuring the film thickness of various samples 100. As shown in Fig. 11, the sample 100 can be a semiconductor element 100A, a flat panel display 100B, a film member 100C, an electronic component 100D, or a component other than an electronic component 100E.

[0052] That is, the film thickness measuring apparatus 1 may measure the thickness of the film 101 formed on the substrate 102, which is a wafer, of the semiconductor element 100A. In this case, the apparatus configuration uses a wafer transport and holding mechanism including an arm, a cassette, a hoop, a conveyor, a moving stage, etc.

[0053] Furthermore, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the substrate 102 made of glass, film, sheet, etc., for the flat panel display 100B. In this case, the device configuration uses a transport and holding mechanism including an arm, a glass table, a conveyor, a moving stage, etc.

[0054] Furthermore, the film thickness measuring device 1 may measure the thickness of a film 101 formed on a substrate 102 made of glass, a film, a sheet, or the like, for a film member 100C. In this case, the device configuration uses a transport and holding mechanism including an arm, a glass table, a conveyor, a moving stage, and the like. Note that, for the film member 100C, as shown in FIG. 12, for example, images of the film member 100C being transported in one direction may be continuously captured, and the captured image areas may be joined together to measure the film thickness of the entire film member 100C being transported.

[0055] Furthermore, film thickness measuring apparatus 1 may measure the thickness of film 101 formed on substrate 102, which is a substrate, of electronic component 100D. In this case, the apparatus configuration uses a wafer transport and holding mechanism including an arm, cassette, hoop, conveyor, sample stage, moving stage, etc.

[0056] Furthermore, the film thickness measuring apparatus 1 may measure the thickness of the film 101 formed on the substrate 102 of the part 100E. The film on the part 100E is, for example, a thin film on a molded product, and in this case, film thickness measurement means, for example, measuring the thickness of a thin film coating. The apparatus is configured using a wafer transport and holding mechanism including an arm, cassette, hoop, conveyor, sample table, moving stage, etc.

[0057] Furthermore, while the above-described film thickness measurement derives a relative film thickness distribution, it is also possible to detect spectral information (reference spectral information) at a single point on the sample 100 and derive the absolute film thickness value for each area based on the relative film thickness distribution and the reference spectral information. FIG. 13 is a schematic diagram of a film thickness measurement apparatus 1A according to a modified example. The film thickness measurement apparatus 1A includes a half mirror 29 and a spectrometer 50 in addition to the components of the film thickness measurement apparatus 1 described in the embodiment. The half mirror 29 reflects light from a single point, for example, near the center of the sample 100. The spectrometer 50 acquires reference spectral information, which is the optical spectrum data of the light at that single point. By acquiring the reference spectral information in this manner, the value of m in equations (7) and (8) can be determined, and not only the amount of change in relative film thickness but also the absolute film thickness value for each area can be derived. Note that the method for measuring the absolute film thickness is not limited to the above. [Explanation of symbols]

[0058] 1, 1A...film thickness measuring device, 10...light source (light irradiation unit), 10d...light guide plate, 22...inclined dichroic mirror, 23, 24...area sensor (imaging unit), 25, 26...bandpass filter, 30...control device (analysis unit), 100...sample (object).

Claims

[Claim 1] a light irradiation unit that irradiates the object with light in a planar manner; an optical element whose transmittance and reflectance change depending on the wavelength in a predetermined wavelength range and separates light from the object by transmitting and reflecting it; an imaging unit that captures an image of the light separated by the optical element; an analysis unit that estimates a film thickness of the object based on a signal from the imaging unit that captures the light, The light irradiating unit irradiates the optical element with light having a wavelength included in the predetermined wavelength range.

Images