Film thickness measuring apparatus and film thickness measuring method

Abstract

To enable accurate derivation of wavelengths of light to acquire appropriate images.SOLUTION: A film thickness measurement device is provided, comprising a light irradiation unit for irradiating an object with planer light, an optical element provided with a transmittance and reflectance that vary with wavelength in a given wavelength range and configured to separate the light from the object through transmission and reflection, an image capturing unit for imaging the light separated by the optical element, and an analysis unit configured to estimate a film thickness of the object on the basis of a signal from the image capturing unit that images of the light, where the light irradiation unit irradiates light of a wavelength within the given wavelength range of the optical element.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] For example, in semiconductor manufacturing equipment and the like, it is important to form a film uniformly on the wafer surface. When the in-plane uniformity of the film thickness value is poor, failure factors such as wiring defects and voids occur, and the yield deteriorates. In this case, an increase in process time and materials leads to a problem of deteriorated productivity. For this reason, in semiconductor manufacturing equipment and the like, usually, the film thickness is measured by a point sensor or a line scan (see, for example, Patent Document 1) or the like, and it is determined whether or not a desired film thickness distribution is obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the method of measuring the film thickness by the above-described point sensor or line scan, etc., there is a problem that the measurement time becomes long.

[0005] One aspect of the present invention has been made in view of the above circumstances, and an object thereof is to provide a film thickness measuring apparatus and a film thickness measuring method capable of measuring the film thickness at high speed.

Means for Solving the Problems

[0006] The film thickness measuring apparatus according to one aspect of the present invention includes a light irradiation unit that irradiates light in a planar shape onto an object, an optical element that has a transmittance and a reflectance that change according to wavelength in a predetermined wavelength range and separates the light from the object by transmitting and reflecting the light, 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. The light irradiation unit irradiates light having a wavelength included in the predetermined wavelength range of the optical element.

[0007] In the film thickness measuring apparatus according to one aspect of the present invention, light having a wavelength included in the predetermined wavelength range of the optical element is irradiated onto the object in a planar shape. Then, in this film thickness measuring apparatus, the optical element separates the light from the object by transmitting and reflecting the light. Here, the transmittance and the reflectance of the optical element change according to wavelength in the predetermined wavelength range. Therefore, the ratio of the transmitted light and the ratio of the reflected light in the light separated by the optical element change according to wavelength. Then, by imaging the separated light in the imaging unit, the ratio of the transmitted light and the ratio of the reflected light can be specified, and as a result, the wavelength can be specified. Further, in the analysis unit, the film thickness of the object is estimated based on the signal from the imaging unit. Since the film thickness can be estimated based on the information indicating the wavelength, as described above, since the wavelength is specified from the imaging result in the imaging unit, by considering the signal (the signal from the imaging unit) including the information of the wavelength, the film thickness of the object can be estimated with high accuracy. And in this film thickness measuring apparatus, since light is irradiated onto the object in a planar shape and the film thickness in the plane of the object is simultaneously estimated according to the light from the object, compared with the case where the film thickness in the plane is estimated while changing the irradiation range of the light by a point sensor or line scan or the like, the film thickness distribution in the plane can be estimated at high speed. As described above, according to the film thickness measuring apparatus according to one aspect of the present invention, the film thickness of the object can be measured at high speed.

[0008] In the above film thickness measuring apparatus, the analysis unit may estimate the film thickness corresponding to each pixel based on the wavelength information for each pixel in the imaging unit. According to such a configuration, the film thickness distribution on the irradiation surface of the object can be estimated in more detail (for each pixel).

[0009] In the film thickness measuring apparatus, the analysis unit may estimate the film thickness in further consideration of the angle of the light irradiated to the object. Since the optical path changes when the angle of the light irradiated to the object changes, it may not be possible to accurately estimate the film thickness from only the information of the wavelength. In this regard, by further considering the angle of the light irradiated to the object, the film thickness can be estimated more accurately according to the actual optical path.

[0010] In the film thickness measuring apparatus, the light irradiation unit may irradiate the object with diffused light. Thereby, the object surface can be irradiated with light uniformly.

[0011] In the film thickness measuring apparatus, the light irradiation unit may have a light guide plate for generating diffused light. Thereby, with a compact configuration, the object surface can be irradiated with light uniformly.

[0012] The film thickness measuring apparatus may further include a band-pass filter disposed between the optical element and the imaging unit. Thereby, light outside a desired wavelength range can be removed, and the accuracy of film thickness estimation can be improved.

[0013] A film thickness measuring method according to an aspect of the present invention includes: a first step of irradiating an object with light in a planar shape; a second step of imaging light separated by an optical element that transmits and reflects light from the object with a transmittance and a reflectance that change according to the wavelength in a predetermined wavelength range; and a third step of deriving a wavelength based on the imaging result and estimating the film thickness of the object based on the wavelength. According to such a film thickness measuring method, similar to the above-described film thickness measuring apparatus, the film thickness of the object can be measured at high speed.

Effects of the Invention

[0014] According to a film thickness measuring apparatus according to an aspect of the present invention, the film thickness of an object can be measured at high speed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0017] FIG. 1 is a diagram schematically showing a film thickness measuring apparatus 1 according to the present embodiment. The film thickness measuring 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 reflected light from the sample 100. The sample 100 may be a light-emitting element such as an LED, a mini-LED, a μ-LED, an SLD element, a laser element, a vertical-cavity surface-emitting laser (VCSEL), an OLED, or the like, or a light-emitting element that adjusts the emission wavelength with a fluorescent substance containing nanodots or the like.

[0018] As shown in FIG. 1, the film thickness measuring apparatus 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 the light in a planar manner, for example, on substantially the entire surface of the sample 100. The light source 10 is a light source capable of uniformly irradiating 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 according to the light irradiated 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. According to such a flat dome type light source 10A, it is possible to suppress specular reflection while securing 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. The light irradiated from the LED 10e is irradiated onto the inner surface of the dome portion 10f, the diffused light from the inner surface of the dome portion 10f is reflected by the sample 100, and 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, an Xe lamp, or the like.

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

[0021] FIG. 3 is a diagram for explaining the relationship between the characteristics of the inclined dichroic mirror 22 and the wavelength of the light emitted from the light source 10. In FIG. 3, the horizontal axis represents the wavelength, and the vertical axis represents the transmittance of the inclined dichroic mirror 22. As shown in the characteristic X4 of the inclined dichroic mirror 22 in FIG. 3, in the inclined dichroic mirror 22, in a predetermined wavelength range X10, the transmittance (and reflectance) of the light changes gently according to the change in the wavelength, and in the wavelength ranges other than the specific wavelength range, the transmittance (and reflectance) of the light is constant regardless of the change in the wavelength. As shown in FIG. 3, the light X20 output from the light source 10 includes light having wavelengths included in the above-described predetermined wavelength range X10. That is, the light source 10 outputs light having a broad spectrum including the predetermined wavelength range X10. The wavelength range (interference peak wavelength) related to the measurement is determined by the material of the film formed on the sample 100 and the measurement film thickness range.

[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 condenses the light from the incident sample 100. The lens 21 may be disposed in front of (upstream of) the tilted dichroic mirror 22, or may be disposed in the region between the tilted dichroic mirror 22 and the area sensors 23, 24. The lens 21 may be a finite-focus lens or an infinite-focus 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 infinite-focus lens, the lens 21 is a collimator lens that converts the light from the sample 100 into parallel light, and is aberration-corrected so as to obtain parallel light. The light output from the lens 21 is incident on the tilted dichroic mirror 22.

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

[0025] FIG. 4 is a diagram for explaining the spectrum of light and the characteristics of the tilted dichroic mirror 22. In FIG. 4, the horizontal axis represents the wavelength, and the vertical axis represents the spectral intensity (in the case of the spectrum of light) and the transmittance (in the case of the tilted dichroic mirror 22). As shown in the characteristics X4 of the tilted dichroic mirror 22 in FIG. 4, in the tilted dichroic mirror 22, in a predetermined wavelength range (the wavelength range of wavelengths λ1 to λ2), the transmittance (and reflectance) of light changes gently in accordance with the change in wavelength, and in the wavelength ranges other than the predetermined wavelength range (that is, the wavelength side lower than wavelength λ1 and the wavelength side higher than wavelength λ2), the transmittance (and reflectance) of light is made constant regardless of the change in wavelength. In other words, in a specific wavelength band (the wavelength band of wavelengths λ1 to λ2), the transmittance of light changes monotonically increasing (the reflectance changes monotonically decreasing) in accordance with the change in wavelength. Since the transmittance and the reflectance have a negative correlation relationship in which one changes in the direction of increasing while the other changes in the direction of decreasing, hereinafter, there may be cases where it is simply described as "transmittance" without describing " (and reflectance)". Note that "the transmittance of light is constant regardless of the change in wavelength" includes not only the case where it is completely constant but also cases where, for example, the change in transmittance with respect to a change in wavelength of 1 nm is 0.1% or less. On the wavelength side lower than wavelength λ1, the transmittance of light is approximately 0% regardless of the change in wavelength, and on the wavelength side higher than wavelength λ2, the transmittance of light is approximately 100% regardless of the change in wavelength. Note that "the transmittance of light is approximately 0%" includes a transmittance of about 0% + 10%, and "the transmittance of light is approximately 100%" includes a transmittance of about 100% - 10%. In FIG. 4, the waveform X1 represents the waveform of the light output from the light source 10. As shown in the waveform X1 of FIG. 4, the light output from the light source 10 includes light having wavelengths included in a predetermined wavelength range (the wavelength range of wavelengths λ1 to λ2) of the tilted dichroic mirror 22.

[0026] Area sensors 23 and 24 image the light separated by the tilted dichroic mirror 22. Area sensor 23 images the light transmitted by the tilted dichroic mirror 22. Area sensor 24 images the light reflected by the tilted dichroic mirror 22. The wavelength range in which area sensors 23 and 24 have sensitivity corresponds to a predetermined wavelength range in which the light transmittance (and reflectance) changes according to the wavelength change in the tilted dichroic mirror 22. Area sensors 23 and 24 are, for example, monochrome sensors or color sensors. The imaging results (images) by area sensors 23 and 24 are output to the control device 30.

[0027] Bandpass filter 25 is disposed between the tilted dichroic mirror 22 and area sensor 23. Bandpass filter 26 is disposed between the tilted dichroic mirror 22 and area sensor 24. Bandpass filters 25 and 26 may be filters that remove light in a wavelength range other than, for example, the above-described predetermined wavelength range (the wavelength range in which the light transmittance and reflectance change according to the wavelength in the tilted dichroic mirror 22).

[0028] Returning to FIG. 1, the control device 30 is a computer and physically includes a memory such as a RAM and a 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 be configured by a microcomputer or an FPGA.

[0029] The control device 30 estimates the film thickness of the sample 100 based on 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 central wavelength of the tilted dichroic mirror 22 (the central 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 based on these, 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 formula (1). In the following formula (1), λ represents the wavelength centroid, λ0 represents the central 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-mentioned formula (1), as shown in FIG. 5, for a pixel where T (amount of transmitted light) = R (amount of reflected light), λ = λ0 (the central 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 more 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 more 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] Note that the method for deriving the wavelength centroid is not limited to the above. For example, since λ (wavelength centroid) is in a proportional relationship with x below, the wavelength centroid may be derived from the following equations (2) and (3). In the following equation (3), IT represents the transmitted light amount, and IR represents the reflected light amount. Also, when the spectral shape of the measurement target and the line formation of the inclined dichroic mirror 22 are ideal shapes, a and b, which are parameters 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] Note that in reality, there are differences (individual differences) in spectral characteristics between the optical system and the cameras. For the purpose of correcting them, for example, x may be derived by the following equation (4) using the signal intensity of a substrate with known reflection characteristics as a reference. In the following equation (4), ITr represents the transmitted light amount in the reference, and IRr represents the reflected light amount in the reference. x = (IT / ITr - IR / IRr) / 2(IT / ITr + IR / IRr) (4)

[0034] Also, for the purpose of removing the influence of direct light from the light source, x may be derived by the following equation (5) using the signal amount in a non-reflective state. In the following equation (5), ITb represents the transmitted light amount in the non-reflective state, and IRb represents the reflected light amount in the non-reflective state. x = {((IT - ITb) / (ITr - ITb) - (IR - IRb) / (IRr - IRb))} / 2{((IT - ITb) / (ITr - ITb) + (IR - IRb) / (IRr - IRb))} (5)

[0035] Also, in order to comprehensively perform various corrections such as film characteristics, irradiation spectrum, and non-linearity of the inclined dichroic mirror 22, the wavelength centroid (λ) may be approximated by a polynomial as in the following equation (6). Note that each parameter (a, b, c, d, e) in the following equation (6) is determined, for example, by measuring a plurality of samples with different wavelength centroids (film thicknesses). λ = ax^4 + bx^3 + cx^2 + dx + e (6)

[0036] FIG. 6 is a diagram for explaining the principle of film thickness measurement. In FIG. 6, the horizontal axis represents the wavelength and the vertical axis represents the reflectance. In the example shown in FIG. 6, the relationships between the wavelength and the reflectance are shown for each of the examples with a film thickness of 820 nm, 830 nm, and 840 nm. As shown in FIG. 6, the wavelength centroid varies depending on the difference in film thickness. Therefore, by specifying the wavelength centroid, it becomes possible to estimate the film thickness.

[0037] The relationship between the wavelength and the film thickness can be explained by the following equation (7) as shown in FIG. 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 represents the wavelength centroid. 2nd represents the optical path difference (the optical path difference caused by the presence 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 interference condition) 2nd = (m - 1 / 2)λ (m = 1, 2, 3,...) (destructive interference condition) ··· (7)

[0038] Here, the equation (7) showing the relationship between the wavelength and the film thickness described above holds when light is incident perpendicularly on the sample 100. On the other hand, when light is not incident perpendicularly on the sample 100, the above equation (7) does not hold. That is, as shown in FIG. 8, when light is incident on the sample 100 in which the film 101 is disposed on the surface of the substrate 102, the incident angle of light varies depending on the measurement point and the optical path difference varies, so that the film thickness cannot be accurately estimated uniformly by the above equation (7). Therefore, in order to accurately estimate the film thickness at any measurement point (incident angle), a calculation (correction process) corresponding to the measurement point (incident angle) is required.

[0039] FIG. 9 is a diagram for explaining the correction of the film thickness measurement value. As shown in FIG. 9(a), when the incident angle of light is θ, the optical path difference is represented by 2ndcosθ. Thus, the relationship between the wavelength and the film thickness considering the incident angle θ can be explained by the following equation (8), as shown in FIG. 9(b). The control device 30 performs film thickness estimation 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 while further considering the angle of the light irradiated onto the sample 100. 2ndcosθ = mλ (constructive interference condition) 2ndcosθ = (m - 1 / 2)λ (destructive interference condition) ··· (8)

[0040] As described above, the film thickness measuring device 1 implements the film thickness measuring method. The film thickness measuring method includes, for example, a first step of irradiating the sample 100 with light in a planar manner, a second step of imaging the light separated by the inclined dichroic mirror 22 that separates the light transmitted and reflected from the sample 100 by changing the transmittance and reflectance according to the wavelength in a predetermined wavelength range, and a third step of deriving the wavelength based on the imaging result and estimating the film thickness of the sample 100 based on the wavelength.

[0041] Next, the operation and effect of this embodiment will be described.

[0042] The film thickness measuring device 1 according to this embodiment includes a light source 10 that irradiates the sample 100 with light in a planar manner, an inclined dichroic mirror 22 that changes the transmittance and reflectance according to the wavelength in a predetermined wavelength range and separates the light transmitted and reflected from the sample 100, area sensors 23, 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 the signals from the area sensors 23, 24 that have imaged the light. The light source 10 irradiates light having a wavelength included in the predetermined wavelength range of the inclined dichroic mirror 22.

[0043] In the film thickness measuring apparatus 1 according to the present embodiment, the sample 100 is irradiated with light having a wavelength included in a predetermined wavelength range of the inclined dichroic mirror 22 in a planar manner. Then, in the film thickness measuring apparatus 1 according to the present embodiment, the inclined dichroic mirror 22 separates the light from the sample 100 by transmitting and reflecting it. Here, the inclined dichroic mirror 22 has a transmittance and a reflectance that change according to the wavelength in a predetermined wavelength range. Therefore, the ratio of the transmitted light and the ratio of the reflected light in the light separated by the inclined dichroic mirror 22 change according to the wavelength. Then, the separated light is imaged by the area sensors 23 and 24, so that the ratio of the transmitted light and the ratio of the reflected light can be specified, and as a result, the wavelength can be specified. Further, 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 the information indicating the wavelength, as described above, the wavelength is specified from the imaging result of the area sensors 23 and 24, so that the film thickness of the sample 100 can be estimated with high accuracy by considering the signal (the signal from the area sensors 23 and 24) including the information of the wavelength. And in the film thickness measuring apparatus 1 according to the present embodiment, since the sample 100 is irradiated with light in a planar manner and the film thickness in the plane of the sample 100 is simultaneously estimated according to the light from the sample 100, compared with the case where the film thickness in the plane is estimated while changing the light irradiation range by a point sensor or line scan or the like, the film thickness distribution in the plane can be estimated at high speed. As described above, according to the film thickness measuring apparatus 1 according to the present embodiment, the film thickness of the sample 100 can be measured at high speed.

[0044] FIG. 10 is a diagram showing a comparison result between the film thickness measuring apparatus 1 according to the present embodiment and a comparative example. As shown in FIG. 10, when the film thickness is measured one point at a time by a point sensor, for example, it takes about 4 hours for the measurement time. Here, the 4 hours is, for example, the measurement time when detection of about 16,000 points is performed. Further, as shown in FIG. 10, when the film thickness is measured one line at a time by line scanning, for example, it takes about 3 minutes for the measurement time. On the other hand, as shown in FIG. 10, in the film thickness measuring apparatus 1 according to the present embodiment, since the sample 100 is irradiated with light in a planar shape and the film thickness in the plane is measured all at once (simultaneously), the measurement time is about 5 seconds. Thus, the film thickness measuring apparatus 1 according to the present embodiment can estimate the film thickness distribution in the plane at high speed as compared with a point sensor or line scanning according to a comparative example. Note that, in the film thickness measuring apparatus 1 according to the present embodiment, the error between the measurement result and the actual film thickness can be made 0.1% or less. Thus, the film thickness measuring apparatus 1 according to the present embodiment can achieve both shortening of the measurement time regarding the film thickness and improvement of the measurement accuracy. Further, while the configurations related to the point sensor and line scanning are difficult to be in-line (mounted on the apparatus), the film thickness measuring apparatus 1 according to the present embodiment can be easily made in-line compatible.

[0045] In the film thickness measuring apparatus 1 described above, the control device 30 may estimate the film thickness corresponding to each pixel based on the wavelength information for each pixel in the area sensors 23 and 24. According to such a 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 measuring apparatus 1 described above, the control device 30 may estimate the film thickness in further consideration of the angle of the light irradiated to the sample 100. When the angle of the light irradiated to the sample 100 changes, the optical path changes, so there are cases where the film thickness cannot be estimated with high accuracy from only the information of the wavelength. In this regard, by further considering the angle of the light irradiated to 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-described formula (8).

[0047] In the film thickness measuring apparatus 1 described above, the light source 10 may irradiate the sample 100 with diffused light. Thereby, the sample 100 can be irradiated with light uniformly on its surface.

[0048] In the film thickness measuring apparatus 1 described above, the light source 10 may have a light guide plate 10d (see Fig. 2(a)) that generates diffused light. Thereby, with a compact configuration, the sample 100 can be irradiated with light uniformly on its surface.

[0049] The film thickness measuring apparatus 1 may further include band-pass filters 25 and 26 disposed between the inclined dichroic mirror 22 and the area sensors 23 and 24. Thereby, light outside a desired wavelength range can be removed, and the accuracy of film thickness estimation can be improved.

[0050] The film thickness measuring method according to the present embodiment is implemented by the film thickness measuring apparatus 1, and includes a first step of irradiating the sample 100 with light in a planar shape, a second step of imaging the light separated by the inclined dichroic mirror 22 that separates the light transmitted and reflected from the sample 100 with the transmittance and reflectance changing according to the wavelength in a predetermined wavelength range, and a third step of deriving the wavelength based on the imaging result and estimating the film thickness of the sample 100 based on the wavelength. According to such a film thickness measuring method, the film thickness of the sample 100 can be measured at high speed.

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

[0052] That is, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the base material 102, which is a wafer, for the semiconductor element 100A. In this case, as the device configuration, a wafer transfer and holding mechanism including an arm, a cassette, a hoop, a conveyor, a moving stage, etc. is used.

[0053] Further, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the base material 102 composed of glass, film, sheet, etc. for the flat panel display 100B. In this case, as the device configuration, a transfer and holding mechanism including an arm, a glass stage, a conveyor, a moving stage, etc. is used.

[0054] Further, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the base material 102 composed of glass, film, sheet, etc. for the film member 100C. In this case, as the device configuration, a transfer and holding mechanism including an arm, a glass stage, a conveyor, a moving stage, etc. is used. Note that for the film member 100C, for example, as shown in FIG. 12, the film member 100C being conveyed in one direction is continuously imaged, and the imaging regions are joined together, so that the film thickness measurement of the entire conveyed film member 100C may be performed.

[0055] Further, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the base material 102, which is a substrate, for the electronic component 100D. In this case, as the device configuration, a wafer transfer and holding mechanism including an arm, a cassette, a hoop, a conveyor, a sample stage, a moving stage, etc. is used.

[0056] Further, the film thickness measuring device 1 may measure the thickness of the film 101 formed on the base material 102, which is a substrate, for the component 100E. The film of the component 100E is, for example, a thin film such as a molded product, and the film thickness measurement in this case is, for example, the measurement of the thin film coat thickness. As the device configuration, a wafer transfer and holding mechanism including an arm, a cassette, a hoop, a conveyor, a sample stage, a moving stage, etc. is used.

[0057] Also, depending on the film thickness measurement described above, a relative film thickness distribution is derived. In addition to this, by detecting the spectral information (reference spectral information) of a single point on the sample 100, the absolute value of the film thickness of each area may be derived based on the relative film thickness distribution and the reference spectral information. FIG. 13 is a diagram schematically showing a film thickness measuring apparatus 1A according to a modified example. The film thickness measuring apparatus 1A includes a half mirror 29 and a spectroscope 50 in addition to each component of the film thickness measuring apparatus 1 described in the embodiment. The half mirror 29 reflects, for example, the light of a single point near the center of the sample 100. The spectroscope 50 acquires reference spectral information which is the spectral data of the light of the single point. In this way, by acquiring the reference spectral information, the value of m in the equations (7) and (8) is determined, and not only the change amount of the relative film thickness but also the absolute value of the film thickness of each area can be derived. Note that the method for measuring the absolute value of the film thickness is not limited to the above.

Explanation of symbols

[0058] 1, 1A... Film thickness measuring apparatus, 10... Light source (light irradiation unit), 10d... Light guide plate, 22... Inclined dichroic mirror, 23, 24... Area sensor (imaging unit), 25, 26... Band pass filter, 30... Control device (analysis unit), 100... Sample (object).

Claims

1. A light irradiation unit that irradiates a target 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 which separates light from the object by transmitting and reflecting it; an imaging unit having an area sensor having a plurality of pixels and configured to capture an image of the light separated by the optical element; an analysis unit that calculates an amount of reflected light and an amount of transmitted light for each pixel based on an imaging result by the imaging unit, derives a wavelength centroid of light from the object corresponding to each pixel based on the amount of reflected light and the amount of transmitted light for each pixel, and estimates a film thickness of the object corresponding to each pixel based on the wavelength centroid corresponding to each pixel.

2. A film thickness measuring device as described in claim 1, wherein the analysis unit estimates the film thickness by further taking into account the angle of light irradiated to the object.

3. A film thickness measuring device as described in claim 1 or 2, wherein the light irradiation unit irradiates diffuse light onto the object.

4. A film thickness measuring device as described in claim 3, wherein the light irradiation section has a light guide plate that generates the diffused light.

5. A film thickness measuring device as described in any one of claims 1 to 4, further comprising a bandpass filter arranged between the optical element and the imaging unit, the bandpass filter transmitting light in the specified wavelength range.

6. A semiconductor film thickness measurement device for measuring the thickness of a film formed on a substrate of a wafer, comprising: A film thickness measuring device according to any one of claims 1 to 5, a transport and holding mechanism for transporting and holding the wafer, The film thickness measuring device is a semiconductor film thickness measuring device that determines the thickness of a film formed on the wafer held by the transport and holding mechanism.

7. A display film thickness measuring device for measuring the thickness of a film formed on a substrate of a display, comprising: A film thickness measuring device according to any one of claims 1 to 5, a conveying and holding mechanism for conveying the display as the object; The film thickness measuring device is a display film thickness measuring device that determines the thickness of a film formed on the display held by the transport and holding mechanism.

8. A film thickness measuring device for measuring the thickness of a film formed on a substrate of a film member, comprising: A film thickness measuring device according to any one of claims 1 to 5, a conveying mechanism for conveying the film member as the object, The film thickness measuring device is a film thickness measuring device that determines the thickness of the film formed on the film member transported by the transport mechanism.

9. A method for producing a light-emitting device comprising: a first step of irradiating a target object with light in a planar manner; a second step of capturing an image of light separated by transmitting and reflecting light from the object using an optical element whose transmittance and reflectance change monotonically depending on the wavelength in a predetermined wavelength range, using an area sensor having a plurality of pixels; a third step of calculating an amount of reflected light and an amount of transmitted light for each pixel based on the image pickup result obtained in the second step; a fourth step of deriving a wavelength centroid of light from the object corresponding to each pixel based on the amount of reflected light of each pixel and the amount of transmitted light of each pixel; and a fifth step of estimating a film thickness of the object corresponding to each pixel based on the wavelength centroid corresponding to each pixel.

10. The film thickness measurement method according to claim 9, comprising the steps of: the object is a wafer, The fifth step of the semiconductor film thickness measuring method comprises determining a thickness of a film formed on the substrate of the wafer.

11. The film thickness measurement method according to claim 9, comprising the steps of: the object is a display, The display film thickness measuring method further comprises determining a thickness of the film formed on the substrate of the display in the fifth step.

12. The film thickness measurement method according to claim 9, comprising the steps of: the object is a film member, The method for measuring film thickness, further comprising determining a thickness of the film formed on the substrate of the film member in the fifth step.

Images