Film thickness measuring device and film thickness measuring method

Abstract

A film thickness measuring device includes: a light irradiation section that irradiates light in a planar manner with respect to an object; an optical element whose transmittance and reflectance vary in correspondence with a wavelength in a prescribed wavelength band, and separates light from the object by transmission and reflection; an imaging section that images the light separated by the optical element; and an analysis section that estimates a film thickness of the object based on a signal from the imaging section that images the light. The light irradiation section irradiates light of a wavelength included in the prescribed wavelength band of the optical element.

Description

Technical Field

[0001] One aspect of the present invention relates to a film thickness measuring device and a film thickness measuring method. Background Technology

[0002] In semiconductor manufacturing equipment, it is crucial to achieve uniform film deposition on the wafer surface. Poor in-plane uniformity of film thickness is a major cause of defects such as poor wiring or voids, leading to a decline in yield. In such cases, increased process time and materials further degrade production efficiency. Therefore, in semiconductor manufacturing equipment, film thickness is typically measured using point sensors or line scanning (e.g., see Patent Document 1) to determine whether the desired film thickness distribution has been achieved.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-205132 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] Here, in the aforementioned methods for measuring film thickness using point sensors or line scanning, the increased measurement time becomes a problem.

[0008] One aspect of the present invention is made in view of the above-mentioned actual situation, and its object is to provide a film thickness measuring device and a film thickness measuring method that can measure film thickness at high speed.

[0009] Technical means to solve the problem

[0010] One aspect of the film thickness measuring apparatus of the present invention comprises: a light irradiation unit that irradiates light in a planar manner relative to an object; an optical element whose transmittance and reflectance vary with wavelength in a predetermined wavelength band, thereby separating light from the object by transmitting and reflecting light; an imaging unit that captures an image of the light separated by the optical element; and a resolution unit that estimates the film thickness of the object based on a signal from the imaging unit that captured the light; wherein the light irradiation unit irradiates light of a wavelength included in the predetermined wavelength band of the optical element.

[0011] In one aspect of the film thickness measuring apparatus of the present invention, light of a wavelength within a predetermined wavelength band is irradiated onto an object surface by an optical element. In this film thickness measuring apparatus, the optical element separates the light from the object by transmitting and reflecting it. Here, the transmittance and reflectance of the optical element vary with wavelength within the predetermined wavelength band. Therefore, the proportion of light transmitted and reflected in the separated light varies with wavelength. Thus, by imaging the separated light in the imaging unit, the proportion of transmitted light and the proportion of reflected light can be specified, and consequently, the wavelength can be specified. Furthermore, in the analysis unit, the film thickness of the object is estimated based on the signal from the imaging unit. In cases where the film thickness can be estimated based on information representing the wavelength, as described above, based on the imaging results of the imaging unit, the wavelength is specified, and therefore, by considering the signal (from the imaging unit) containing information of that wavelength, the film thickness of the object can be estimated with high accuracy. Therefore, in this film thickness measuring apparatus, since light is irradiated onto the surface of the object while simultaneously estimating the film thickness within the surface of the object corresponding to the light from the object, the film thickness distribution within the surface can be estimated at a high speed compared to the case where the film thickness within the surface is estimated while changing the irradiation range of the light using a point sensor or line scanning. As described above, according to one aspect of the film thickness measuring apparatus of the present invention, the film thickness of an object can be measured at a high speed.

[0012] In the aforementioned film thickness measuring device, the resolution unit can also estimate the film thickness corresponding to each pixel based on the wavelength information of each pixel of the imaging unit. According to this structure, the film thickness distribution on the irradiated surface of the object can be estimated in more detail (per pixel).

[0013] In the aforementioned film thickness measuring device, the analysis unit can further consider the angle of light illuminating the object to estimate the film thickness. Since the optical path changes if the angle of light illuminating the object changes, there are cases where the film thickness cannot be estimated with high accuracy based solely on wavelength information. By further considering the angle of light illuminating the object, the film thickness can be estimated with higher accuracy, corresponding to the actual optical path.

[0014] In the aforementioned film thickness measuring device, the light irradiation unit can also irradiate diffused light relative to the object. This allows for uniform irradiation of light relative to the surface of the object.

[0015] In the aforementioned film thickness measuring device, the light irradiation unit may also include a light guide plate that generates diffused light. This allows for a compact structure that uniformly irradiates light relative to the surface of the object.

[0016] The aforementioned film thickness measuring device may also include a bandpass filter disposed between the optical element and the imaging unit. This removes light outside the desired wavelength range, improving the accuracy of film thickness estimation.

[0017] One aspect of the film thickness measurement method of the present invention includes: a first step of irradiating light onto a surface of an object; a second step of imaging the light separated by an optical element, wherein the transmittance and reflectance of the optical element vary with wavelength in a predetermined wavelength band, and the light from the object is separated by transmission and reflection; and a third step of deriving the wavelength based on the imaging result, and estimating the film thickness of the object based on the wavelength. According to this film thickness measurement method, the film thickness of an object can be measured at high speed, similar to the film thickness measurement device described above.

[0018] The effects of the invention

[0019] According to one aspect of the film thickness measuring device of the present invention, the film thickness of an object can be measured at high speed. Attached Figure Description

[0020] Figure 1 This is a diagram schematically showing a film thickness measuring device according to an embodiment of the present invention.

[0021] Figure 2 This is a diagram illustrating an example of a light source. Figure 2 (a) shows the lighting of the flat dome. Figure 2 (b) shows the dome lighting.

[0022] Figure 3 This is a diagram illustrating the relationship between the characteristics of a dichroic mirror and the wavelength of light emitted from a light source.

[0023] Figure 4 It is a diagram illustrating the spectrum of light and the characteristics of a tilting dichroic mirror.

[0024] Figure 5 It is a graph illustrating the wavelength shift corresponding to the amount of transmitted light and the amount of reflected light.

[0025] Figure 6 It is a graph showing the relationship between wavelength and film thickness.

[0026] Figure 7 This is a diagram illustrating the principle of film thickness measurement.

[0027] Figure 8 It is a diagram illustrating the different angles of light incidence relative to the camera system.

[0028] Figure 9 This is a graph illustrating the correction for the film thickness measurement values.

[0029] Figure 10 This is a graph showing the comparison results between the film thickness measuring device of this embodiment and the comparative example.

[0030] Figure 11 This is a diagram illustrating the film thickness measuring device for a modified example.

[0031] Figure 12 This is a diagram illustrating the film thickness measuring device for a modified example.

[0032] Figure 13 This is a schematic diagram showing a film thickness measuring device for a deformed example. Detailed Implementation

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in each drawing, the same or equivalent parts are given the same reference numerals, and repeated descriptions are omitted.

[0034] Figure 1 This diagram schematically shows the film thickness measuring apparatus 1 according to this embodiment. The film thickness measuring apparatus 1 is a device that irradiates light in a planar manner relative to the sample 100 (object) and measures the thickness of the 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, micro LED, μLED, SLD element, laser element, vertical laser element (VCSEL), OLED, etc., or a light-emitting element whose emission wavelength is adjusted by including fluorescent materials such as nanodots.

[0035] like Figure 1 As shown, the film thickness measuring device 1 includes: a light source 10 (light irradiation unit), a camera system 20, and a control device 30 (resolution unit).

[0036] Light source 10 illuminates the sample 100 in a planar manner. For example, light source 10 illuminates the sample 100 in a planar manner, covering approximately the entire surface of the sample 100. Light source 10 is, for example, a light source capable of uniformly illuminating the surface of the sample 100, illuminating diffused light relative to the sample 100. Figure 2 As shown, the light source 10 can be a so-called planar dome-shaped light source 10A (see reference). Figure 2 (a) can also be a dome-shaped light source 10B (see reference). Figure 2 (b) Figure 2 The light source 10A shown in (a) includes an LED 10c and a light guide plate 10d. The light guide plate 10d generates diffused light corresponding to the light irradiated from the LED 10c. The diffused light generated by the light guide plate 10d is reflected in the sample 100 and input to the camera system 20. With such a planar dome-shaped light source 10A, sufficient field of view (e.g., about 300 mm) can be ensured while suppressing intrusion. The light source 10B includes an LED 10e and a dome 10f. Light irradiated from the LED 10e shines towards the inner surface of the dome 10f, and the diffused light from the inner surface of the dome 10f is reflected in the sample 100. The reflected light from the sample 100 is input to the camera system 20. The light source 10 can be a surface illumination unit utilizing a white LED, a halogen lamp, or an Xe lamp, etc.

[0037] The light source 10 illuminates the sample 100 with light from a predetermined wavelength band encompassed by the tilting dichroic mirror 22 (details described later) of the camera system 20. Details are described later, but the tilting 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 tilting dichroic mirror 22 vary with wavelength within the aforementioned predetermined wavelength band.

[0038] Figure 3 This is a graph illustrating the relationship between the characteristics of the tilting dichroic mirror 22 and the wavelength of the light emitted from the light source 10. Figure 3 In the diagram, the horizontal axis represents wavelength, and the vertical axis represents the transmittance of the tilted dichroic mirror 22. For example... Figure 3 As shown in characteristic X4 of the tilting dichroic mirror 22, in the tilting dichroic mirror 22, within a specified wavelength band X10, the transmittance (and reflectance) of light changes smoothly corresponding to the change in wavelength; outside this specified wavelength band, the transmittance (and reflectance) of light is set to a constant regardless of the change in wavelength. Figure 3 As shown, the light X20 emitted from the light source 10 contains the wavelengths included in the aforementioned specified wavelength band X10. That is, the light source 10 emits light with a broad spectrum containing the specified wavelength band X10. Furthermore, the wavelength band (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.

[0039] return Figure 1 The camera system 20 is configured to include a lens 21, a tilting dichroic mirror 22 (optical element), area sensors 23 and 24 (image capture unit), and bandpass filters 25 and 26.

[0040] Lens 21 is a lens that focuses the incident light from sample 100. Lens 21 can be positioned upstream of the tilting dichroic mirror 22, or in the region between the tilting dichroic mirror 22 and area sensors 23 and 24. Lens 21 can be a finite-focus lens or an infinite-focus lens. When lens 21 is a finite-focus lens, the distance from lens 21 to area sensors 23 and 24 is set to a predetermined value. When lens 21 is an infinite-focus lens, it is a collimating lens that converts the light from sample 100 into parallel light, thereby correcting aberrations by obtaining parallel light. Light output from lens 21 is incident on the tilting dichroic mirror 22.

[0041] The tilting dichroic mirror 22 is a mirror made using special optical materials, and it is an optical element that separates light from the sample 100 by transmitting and reflecting it according to wavelength. The tilting dichroic mirror 22 is configured such that the transmittance and reflectance of light vary according to wavelength within a specified wavelength band.

[0042] Figure 4 This is a diagram illustrating the spectrum of light and the characteristics of the tilting dichroic mirror 22. In Figure 4 In the diagram, the horizontal axis represents wavelength, and the vertical axis represents spectral intensity (in the case of the light spectrum) and transmittance (in the case of tilted dichroic mirror 22). For example... Figure 4 As shown in characteristic X4 of the tilting dichroic mirror 22, in the tilting dichroic mirror 22, within a defined wavelength band (the wavelength band of wavelength λ1 to λ2), the transmittance (and reflectance) of light changes smoothly corresponding to the change in wavelength. In wavelength bands outside this defined wavelength band (i.e., the lower wavelength side than wavelength λ1 and the higher wavelength side than wavelength λ2), the transmittance (and reflectance) is set to a constant regardless of the change in wavelength. In other words, within the defined wavelength band (the wavelength band of wavelength λ1 to λ2), the transmittance of light monotonically increases (and the reflectance monotonically decreases) corresponding to the change in wavelength. Since there is a negative correlation between transmittance and reflectance—if one changes in the direction of increase, the other changes in the direction of decrease—it will be simply referred to as "transmittance" below, rather than "transmittance (and reflectance)". Furthermore, the statement "the transmittance of light remains constant regardless of wavelength" includes not only cases where it is completely constant, but also cases where the transmittance changes by less than 0.1% relative to a 1 nm change in wavelength. At wavelengths lower than λ1, the transmittance is approximately 0% regardless of wavelength change; at wavelengths higher than λ2, the transmittance is approximately 100% regardless of wavelength change. Moreover, "the transmittance of light is approximately 0%" includes transmittance of approximately 0% + 10%, and "the transmittance of light is approximately 100%" includes transmittance of approximately 100% - 10%. Figure 4 In the diagram, waveform X1 represents the waveform of the light output from light source 10. For example... Figure 4 As shown in waveform X1, the light output from the light source 10 includes the wavelengths contained in the specified wavelength band (wavelength band of wavelength λ1 to λ2) of the tilted dichroic mirror 22.

[0043] Area sensors 23 and 24 capture images of the light separated by the tilted dichroic mirror 22. Area sensor 23 captures images of the light transmitted through the tilted dichroic mirror 22. Area sensor 24 captures images of the light reflected from the tilted dichroic mirror 22. The wavelength range of sensitivity of area sensors 23 and 24 corresponds to a predetermined wavelength band in which the transmittance (and reflectance) of light in the tilted dichroic mirror 22 varies with the wavelength. Area sensors 23 and 24 are, for example, monochrome sensors or color sensors. The image captured by area sensors 23 and 24 is output to control device 30.

[0044] A bandpass filter 25 is disposed between the tilted dichroic mirror 22 and the area sensor 23. A bandpass filter 26 is disposed between the tilted dichroic mirror 22 and the area sensor 24. The bandpass filters 25 and 26 may also be filters for removing light from wavelength bands other than the specified wavelength bands (wavelength bands in the tilted dichroic mirror 22 where the transmittance and reflectance of light vary with wavelength).

[0045] return Figure 1 The control device 30 is a computer, physically configured with a memory 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 programs stored in the memory using the CPU of the computer system. The control device 30 can also be constructed from a microcomputer or an FPGA.

[0046] The control device 30 estimates the film thickness of sample 100 based on signals from area sensors 23 and 24 that have captured light. The control device 30 estimates the film thickness corresponding to each pixel based on the wavelength information of each pixel in area sensors 23 and 24. More specifically, the control device 30 derives the wavelength centroid of light for each pixel based on: a specific amount of transmitted light based on the imaging results (signals from area sensor 23), a specific amount of reflected light based on the imaging results (signals from area sensor 24), the center wavelength of the tilted dichroic mirror 22 (the center wavelength of a predetermined wavelength band), and the width of the tilted dichroic mirror 22, and estimates the film thickness corresponding to each pixel based on this wavelength centroid. The width of the tilted dichroic mirror 22 is, for example, the wavelength width from wavelengths with 0% transmittance to wavelengths with 100% transmittance in the tilted dichroic mirror 22.

[0047] 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.

[0048] λ=λ0+A(TR) / 2(T+R) (1)

[0049] Figure 5 This is a graph illustrating the wavelength shift corresponding to the amount of transmitted and reflected light. Based on equation (1) above, λ (wavelength centroid) is derived, as follows... Figure 5As shown, for pixels where T (transmitted light) = R (reflected light), λ is set to λ0 (the center wavelength of the tilted dichroic mirror 22). For pixels where T < R, i.e., pixels with more reflected light than transmitted light, λ is set to λ1 (the wavelength on the shorter wavelength side than λ0). For pixels where T > R, i.e., pixels with more transmitted light than reflected light, λ is set to λ2 (the wavelength on the longer wavelength side than λ0). Thus, the value of λ (wavelength centroid) shifts based on the amount of transmitted and reflected light (wavelength shift).

[0050] Furthermore, the method for deriving the wavelength centroid is not limited to the above. For example, since λ (wavelength centroid) has a proportional relationship with the following x, the wavelength centroid can be derived according to the following equations (2) and (3). In the following equation (3), I T Indicates the amount of light transmitted, I R This represents the amount of reflected light. Furthermore, if the spectral shape of the object being measured and the line formation of the tilting dichroic mirror 22 are ideal, the parameters a and b in equation (2) are determined by the optical characteristics of the tilting dichroic mirror 22.

[0051] λ=ax+b (2)

[0052] x = I T -I R / 2(I T +I R (3)

[0053] Furthermore, since there are actually differences in the spectral characteristics between optical systems and cameras (individual differences), for the purpose of correcting them, for example, the signal strength of a substrate with known reflection characteristics can be used as a reference to derive x according to the following equation (4). In the following equation (4), I Tr I represents the amount of transmitted light for reference. Rr This represents the amount of reflected light for reference.

[0054] x=(I T / I Tr -I R / I Rr ) / 2(I T / I Tr +I R / I Rr (4)

[0055] Furthermore, to remove the influence of direct light from the light source, x can be derived from the signal quantity in the non-reflective state according to the following equation (5). In the following equation (5), I Tb I represents the amount of light transmitted in the non-reflective state. Rb This represents the amount of reflected light in a non-reflective state.

[0056] x={(I T -I Tb ) / (I Tr -I Tb )-(I R -I Rb ) / (I Rr -I Rb )} / 2{(I T -I Tb ) / (I Tr -I Tb )+(I R -I Rb ) / (I Rr -I Rb )}(5)

[0057] Furthermore, in order to comprehensively implement various corrections for film properties, illumination spectrum, nonlinearity of tilting dichroic mirror 22, etc., the wavelength centroid (λ) can also be approximated by a polynomial as shown in equation (6) below. In addition, the parameters (a, b, c, d, e) in equation (6) below are determined, for example, by measuring samples with different wavelength centroids (film thicknesses) multiple times.

[0058] λ = ax 4 +bx 3 +cx 2 +dx+e (6)

[0059] Figure 6 This is a diagram illustrating the principle of film thickness measurement. In Figure 6 In the diagram, the horizontal axis is set to wavelength, and the vertical axis is set to reflectivity. Figure 6 The examples shown illustrate the relationship between wavelength and reflectivity for examples with film thicknesses of 820 nm, 830 nm, and 840 nm. Figure 6 As shown, the wavelength centroid varies with the film thickness. Therefore, the film thickness can be estimated by using the centroid of a specific wavelength.

[0060] The relationship between wavelength and film thickness can be as follows: Figure 7 As shown, this is explained by the following equation (7). In the following equation (7), n represents the refractive index of the film, d represents the film thickness, m represents a positive integer (1, 2, 3, ...), λ represents the wavelength centroid, and 2nd represents the optical path difference (the optical path difference caused by the configuration of the film). The control device 30 estimates the film thickness corresponding to each pixel based on the following equation (7) and the wavelength centroid of each pixel.

[0061] 2nd = mλ (m = 1, 2, 3, ...) (Enhancing condition)

[0062] 2nd=(m-1 / 2)λ(m=1、2、3、…)(weakening condition)··(7)

[0063] Here, equation (7) relating wavelength and film thickness holds true when light is incident perpendicularly to the sample 100. On the other hand, equation (7) does not hold true when light is not incident perpendicularly to the sample 100. That is, as... Figure 8 As shown, when light is incident on a sample 100 on which a film 101 is disposed on the surface of a substrate 102, the incident angle of the light varies from measurement point to measurement point and the optical path difference is different. Therefore, it is not possible to estimate the film thickness with high accuracy using the above formula (7). Therefore, in order to estimate the film thickness with high accuracy at any measurement point (incident angle), a calculation (correction process) corresponding to the measurement point (incident angle) is required.

[0064] Figure 9 This is a graph illustrating the correction for the film thickness measurement values. For example... Figure 9 As shown in (a), when the incident angle of light is θ, the optical path difference is expressed as 2ndcosθ. Therefore, the relationship between the wavelength and the film thickness considering the incident angle θ can be expressed as follows: Figure 9 As shown in (b), it is explained by the following equation (8). The control device 30 estimates the film thickness corresponding to the measurement point (incident angle) based on the following equation (8). In this way, the control device 30 can also further consider the angle of light irradiating the sample 100 and estimate the film thickness according to the centroid of the wavelength.

[0065] 2ndcosθ=mλ (enhancing condition)

[0066] 2ndcosθ=(m-1 / 2)λ (weakening condition)··(8)

[0067] As described above, the film thickness measuring device 1 implements a film thickness measuring method. The film thickness measuring method includes, for example, the following steps: a first step, in which light is irradiated in a planar manner relative to the sample 100; a second step, in which an image is captured of the light separated by a tilting dichroic mirror 22, the transmittance and reflectance of which vary with wavelength in a specified wavelength band, thereby separating the light from the sample 100 by transmitting and reflecting it; and a third step, in which the wavelength is derived based on the image capture result, and the film thickness of the sample 100 is estimated based on the wavelength.

[0068] Secondly, the effects of this implementation method will be explained.

[0069] The film thickness measuring device 1 of this embodiment includes: a light source 10 that illuminates light in a planar manner relative to the sample 100; a tilting dichroic mirror 22 that separates light from the sample 100 by transmitting and reflecting light within a predetermined wavelength band, with transmittance and reflectance varying according to wavelength; area sensors 23 and 24 that capture images of the light separated by the tilting 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 captured the light; the light source 10 illuminates light within the predetermined wavelength band of the tilting dichroic mirror 22.

[0070] In the film thickness measuring apparatus 1 of this embodiment, light of a wavelength within a predetermined wavelength band of the tilting dichroic mirror 22 is irradiated planarly relative to the sample 100. Thus, in the film thickness measuring apparatus 1 of this embodiment, the tilting dichroic mirror 22 separates the light from the sample 100 by transmitting and reflecting it. Here, the transmittance and reflectance of the tilting dichroic mirror 22 vary with wavelength within the predetermined wavelength band. Therefore, the proportion of transmitted light and the proportion of reflected light in the light separated by the tilting dichroic mirror 22 vary with wavelength. Therefore, by capturing images of the separated light in the area sensors 23 and 24, the proportion of transmitted light and the proportion of reflected light can be specified, and consequently, the wavelength can be specified. Furthermore, in the control device 30, the film thickness of the sample 100 is estimated based on the signals from the area sensors 23 and 24. Since the film thickness can be estimated based on information representing the wavelength, as described above, the wavelength is estimated based on the imaging results of area sensors 23 and 24. Therefore, by considering the signal (signal from area sensors 23 and 24) containing information about that wavelength, the film thickness of sample 100 can be estimated with high accuracy. Thus, in the film thickness measuring apparatus 1 of this embodiment, since light is irradiated in a planar manner relative to sample 100, and the in-plane film thickness of sample 100 is estimated corresponding to the light from sample 100, the in-plane film thickness distribution can be estimated at high speed compared to the case where the in-plane film thickness is estimated while changing the irradiation range of light using a point sensor or line scanning. As described above, the film thickness measuring apparatus 1 of this embodiment can measure the film thickness of sample 100 at high speed.

[0071] Figure 10 This is a graph showing the comparison results between the film thickness measuring device 1 of this embodiment and the comparative example. (See figure) Figure 10 As shown, when measuring the film thickness point by point using a point sensor, the measurement time is, for example, approximately 4 hours. Furthermore, this 4-hour measurement time is for, for example, performing approximately 16,000 point measurements. Additionally, as... Figure 10 As shown, when measuring the film thickness one line at a time via line scanning, the measurement time is, for example, approximately 3 minutes. In contrast, as... Figure 10As shown, in the film thickness measuring apparatus 1 of this embodiment, since light is irradiated onto the sample 100 surface and the film thickness within the surface is measured simultaneously, the measurement time is approximately 5 seconds. Thus, compared to point sensors or line scans in comparative examples, the film thickness measuring apparatus 1 of this embodiment can rapidly estimate the film thickness distribution within the surface. Furthermore, in the film thickness measuring apparatus 1 of this embodiment, the error between the measurement result and the actual film thickness can be set to 0.1% or less. Therefore, the film thickness measuring apparatus 1 of this embodiment achieves both a reduction in measurement time related to film thickness and an improvement in measurement accuracy. Additionally, while the structures involved in point sensors and line scans are difficult to embed (mount into the device), the film thickness measuring apparatus 1 of this embodiment can be easily embedded accordingly.

[0072] In the aforementioned film thickness measuring device 1, the control device 30 can also estimate the film thickness corresponding to each pixel based on the wavelength information of each pixel in the area sensors 23 and 24. According to this structure, the film thickness distribution on the irradiated surface of the sample 100 can be estimated in more detail (per pixel).

[0073] In the above-described film thickness measuring device 1, the control device 30 can further consider the angle of the light illuminating the sample 100 to estimate the film thickness. Since the optical path changes if the angle of the light illuminating the sample 100 changes, there is a situation where the film thickness cannot be estimated with high accuracy based solely on wavelength information. By further considering the angle of the light illuminating the sample 100, the film thickness can be estimated with higher accuracy by corresponding to the actual optical path. Specifically, the film thickness is estimated using the above-described equation (8).

[0074] In the film thickness measuring device 1 described above, the light source 10 can also irradiate diffused light relative to the sample 100. As a result, light can be uniformly irradiated relative to the surface of the sample 100.

[0075] In the above-described film thickness measuring device 1, the light source 10 may also have a light guide plate 10d that generates diffused light (see reference). Figure 2 (a)). Thus, a compact structure can be formed, and light can be uniformly irradiated relative to the surface of sample 100.

[0076] The aforementioned film thickness measuring device 1 may also include bandpass filters 25 and 26 disposed between the tilting dichroic mirror 22 and the area sensors 23 and 24. This removes light outside the desired wavelength range, improving the accuracy of film thickness estimation.

[0077] The film thickness measurement method of this embodiment is performed by a film thickness measurement device 1 and includes: a first step in which light is irradiated planarly relative to the sample 100; a second step in which an image is captured of the light separated by a tilting dichroic mirror 22, the tilting dichroic mirror 22 having transmittance and reflectance varying with wavelength in a specified wavelength band and separating the light from the sample 100 by transmitting and reflecting it; and a third step in which the wavelength is derived based on the image capture result, and the film thickness of the sample 100 is estimated based on the wavelength. According to this film thickness measurement method, the film thickness of the sample 100 can be measured at high speed.

[0078] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. The film thickness measuring device 1 can be applied to the film thickness measurement of various samples 100. Figure 11 As shown, as sample 100, semiconductor element 100A, flat panel display 100B, film component 100C, electronic component 100D, and other components 100E besides electronic component are considered.

[0079] That is, the film thickness measuring device 1 can also measure the thickness of the film 101 formed on the substrate 102, which serves as a wafer, for semiconductor device 100A. In this case, as the device structure, a wafer transport and holding mechanism including an arm, a cassette, a front-opening wafer transport box, a conveyor, a moving stage, etc. is used.

[0080] Furthermore, the film thickness measuring device 1, for the flat panel display 100B, can also measure the thickness of the film 101 formed on a substrate 102 made of glass, film, sheet, etc. In this case, as the device structure, a conveying and holding mechanism including an arm, a glass stage, a conveyor, a moving platform, etc. is used.

[0081] Furthermore, the film thickness measuring device 1 can also measure the thickness of the film 101 formed on a substrate 102 made of glass, film, sheet, etc., for the film component 100C. In this case, as the device structure, a conveying and holding mechanism including an arm, a glass stage, a conveyor, a moving platform, etc. is used. Additionally, for the film component 100C, for example, a... Figure 12 As shown, the membrane component 100C being transported in one direction is continuously photographed, and the overall membrane thickness of the transported membrane component 100C is measured by combining the photographed areas together.

[0082] Additionally, the film thickness measuring device 1 can also measure the thickness of the film 101 formed on the substrate 102, which serves as the substrate, for electronic components 100D. In this case, the device structure utilizes a wafer transport and holding mechanism that includes an arm, a cassette, a front-opening wafer transfer box, a conveyor, a sample stage, and a moving stage.

[0083] Furthermore, the film thickness measuring device 1 can also measure the thickness of the film 101 formed on the substrate 102, which serves as a substrate, for component 100E. The film of component 100E may be a thin film such as a molded product; in this case, the film thickness measurement is, for example, the measurement of the thin film coating thickness. The device structure utilizes a wafer transport and holding mechanism that includes an arm, a cassette, a front-opening wafer transfer box, a conveyor, a sample stage, and a moving stage.

[0084] In addition, the relative film thickness distribution can be derived through the above film thickness measurement. However, the absolute value of the film thickness in each region can also be derived based on the relative film thickness distribution and the reference spectral information by detecting the spectral information of a certain point of the sample 100 (reference spectral information). Figure 13 This is a schematic diagram showing a modified example of the film thickness measuring device 1A. In addition to the structures of the film thickness measuring device 1 described in the embodiments, the film thickness measuring device 1A also includes a semi-reflective mirror 29 and a beam splitter 50. The semi-reflective mirror 29 reflects light from, for example, a point near the center of the sample 100. The beam splitter 50 acquires the spectroscopic data of the light at that point, i.e., reference spectral information. Thus, by acquiring the reference spectral information and determining the value of m in equations (7) and (8), not only can the relative change in film thickness be derived, but also the absolute value of the film thickness in each region can be derived. Furthermore, the method for measuring the absolute value of film thickness is not limited to the above.

[0085] Explanation of symbols

[0086] 1,1A…film thickness measuring device, 10…light source (light irradiation unit), 10d…light guide plate, 22…tilted dichroic mirror, 23,24…area sensor (camera unit), 25,26…bandpass filter, 30…control device (resolution unit), 100…sample (object).

Claims

1. A film thickness measuring device, wherein, have: The light irradiation section irradiates light onto the object in a planar manner; An optical element whose transmittance and reflectance vary monotonically with respect to wavelength within a specified wavelength band, thereby separating light from the object by transmitting and reflecting it. The camera unit captures images of the light separated by the optical element; The analysis unit, based on the parameters of the optical element and the signal from the imaging unit that has captured the light, determines the wavelength centroid and estimates the film thickness of the object based on the wavelength centroid. The light irradiation section irradiates the optical element with light of a wavelength included in the specified wavelength band.

2. The film thickness measuring device as described in claim 1, wherein, The analysis unit estimates the film thickness corresponding to each pixel based on the wavelength information of each pixel in the imaging unit.

3. The film thickness measuring device as described in claim 1 or 2, wherein, The analytical unit further considers the angle of light illuminating the object to estimate the film thickness.

4. The film thickness measuring device according to any one of claims 1 to 3, wherein, The light irradiation unit irradiates diffused light relative to the object.

5. The film thickness measuring device as described in claim 4, wherein, The light irradiation section has a light guide plate that generates the diffused light.

6. The film thickness measuring device as described in claim 1, wherein, It also includes a bandpass filter disposed between the optical element and the camera unit.

7. A method for measuring film thickness, wherein, Include: In the first step, light is irradiated onto the surface of the object. The second step involves photographing the light separated by an optical element whose transmittance and reflectance vary monotonically with respect to wavelength within a specified wavelength band, and which separates the light from the object by transmitting and reflecting it; and The third step involves determining the wavelength centroid based on the parameters of the optical element and the imaging results, and estimating the film thickness of the object based on the wavelength centroid.

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