Film thickness measuring device and film thickness measuring method

Abstract

A film thickness measuring device comprises a light irradiation unit that irradiates light in a planar shape onto an object, an optical element that separates light from an object by transmitting and reflecting it, wherein the transmittance and reflectance change according to the wavelength in a predetermined wavelength range, an imaging unit that captures 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 captured the light, and the light irradiation unit irradiates light of a wavelength included in the predetermined wavelength range of the optical element.

Description

Technology Field

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

[0002] For example, in semiconductor manufacturing equipment, it is important to deposit a film uniformly on the wafer surface. If the in-plane uniformity of the film thickness value is poor, failure factors such as wiring defects or voids occur, and the yield deteriorates. In this case, it becomes a problem that productivity deteriorates due to increased process time and materials. For this reason, in semiconductor manufacturing equipment, the film thickness is typically measured by a point sensor or line scan (see, for example, Patent Document 1) to determine whether or not the desired film thickness distribution is achieved. Prior art literature

[0003] Patent Document 1: Japanese Published Patent No. 2018-205132 The problem to be solved

[0004] Here, in the method of measuring film thickness using the aforementioned point sensor or line scan, the problem is that the measurement time becomes long.

[0005] One aspect of the present invention is made in consideration of the above circumstances and aims to provide a film thickness measuring device and a film thickness measuring method capable of measuring film thickness at high speed. means of solving the problem

[0006] A film thickness measuring device according to one aspect of the present invention comprises a light irradiation unit that irradiates light in a planar shape onto an object, an optical element that separates light from an object by transmitting and reflecting it, wherein the transmittance and reflectance change according to the wavelength in a predetermined wavelength range, an imaging unit that captures 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 captured the light, and the light irradiation unit irradiates light of a wavelength included in the predetermined wavelength range of the optical element.

[0007] In a film thickness measuring device according to one aspect of the present invention, light of a wavelength included in a predetermined wavelength range of an optical element is irradiated onto an object in a planar shape. Then, in the film thickness measuring device, the optical element separates the light from the object by transmitting and reflecting it. Here, the transmittance and reflectance of the optical element change according to the wavelength in a predetermined wavelength range. Therefore, the ratio of transmitted light and the ratio of reflected light separated by the optical element change according to the wavelength. Then, as the separated light is captured by an imaging unit, the ratio of transmitted light and the ratio of reflected light can be determined, and as a result, the wavelength can be determined. Furthermore, in an 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 information indicating the wavelength, and as described above, the wavelength is determined from the imaging result from the imaging unit, the film thickness of the object can be estimated with high precision by considering a signal (signal from the imaging unit) containing information of the corresponding wavelength. Furthermore, in the film thickness measuring device of the present invention, light is irradiated onto an object in a planar shape, and since the film thickness within the planar surface of the object is simultaneously estimated according to the light from the object, the distribution of film thickness within the planar surface can be estimated at high speed compared to cases where the film thickness within the planar surface is estimated while the irradiation range of light is changed by a point sensor or line scan, etc. As described above, according to the film thickness measuring device according to one aspect of the present invention, the film thickness of an object can be measured at high speed.

[0008] In the above 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, the film thickness distribution on the irradiated surface of the object can be estimated in more detail (for each pixel).

[0009] In the above film thickness measuring device, the analysis unit may estimate the film thickness by further considering the angle of light irradiated onto the object. Since the optical path changes when the angle of light irradiated onto the object changes, there are cases where the film thickness cannot be estimated with high precision from information alone regarding wavelength. In this regard, by further considering the angle of light irradiated onto the object, the film thickness can be estimated with higher precision according to the actual optical path.

[0010] In the above film thickness measuring device, the light irradiation unit may irradiate diffused light onto the object. By doing so, light can be irradiated uniformly onto the surface of the object.

[0011] In the above film thickness measuring device, the light irradiation unit may have a light guide plate that generates diffused light. By doing so, light can be uniformly irradiated onto the surface of an object with a compact configuration.

[0012] The above film thickness measuring device may further include a bandpass filter disposed between the optical element and the imaging unit. By doing so, light outside the desired wavelength range can be removed, thereby improving the precision of film thickness estimation.

[0013] A film thickness measurement method according to one aspect of the present invention comprises: a first step of irradiating light in a planar shape onto an object; a second step of capturing light separated by an optical element that separates light from the object by transmitting and reflecting it, wherein the transmittance and reflectance change according to the wavelength in a predetermined wavelength range; and a third step of deriving a wavelength based on the capture result and estimating the film thickness of the object based on the corresponding 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. Effects of the invention

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

[0015] FIG. 1 is a schematic diagram showing a film thickness measuring device in an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a light source, where FIG. 2(a) shows a flat dome light and FIG. 2(b) shows a dome light. Figure 3 is a diagram illustrating the relationship between the characteristics of a dichroic mirror and the wavelength of light emitted from a light source. Figure 4 is a diagram illustrating the spectrum of light and the characteristics of a slanted dichroic mirror. Figure 5 is a diagram illustrating wavelength shift according to transmitted light and reflected light. Figure 6 is a diagram showing the relationship between wavelength and film thickness. Figure 7 is a diagram explaining the principle of film thickness measurement. Figure 8 is a diagram illustrating the difference in the angle of incidence of light for a camera system. Figure 9 is a diagram illustrating the correction of film thickness measurements. FIG. 10 is a drawing showing the results of a comparison between a film thickness measuring device according to the present embodiment and a comparative example. Figure 11 is a drawing illustrating a film thickness measuring device for a deformation example. FIG. 12 is a drawing illustrating a film thickness measuring device for a deformation example. FIG. 13 is a schematic diagram showing a film thickness measuring device for a deformation example. Specific details for implementing the invention

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

[0017] FIG. 1 is a schematic diagram showing a film thickness measuring device (1) according to the present embodiment. The film thickness measuring device (1) is a device that irradiates light in a planar shape onto a sample (100) (object) 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 device such as an LED, mini LED, μLED, SLD element, laser element, vertical laser element (VCSEL), OLED, etc., or a light-emitting device that adjusts the emission wavelength by a fluorescent material including nanodots, etc.

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

[0019] The light source (10) irradiates light in a planar shape onto the sample (100). For example, the light source (10) irradiates light in a planar shape onto approximately the entire surface of the sample (100). For example, the light source (10) is a light source capable of uniformly irradiating the surface of the sample (100) and irradiates diffused light onto the sample (100). As shown in FIG. 2, the light source (10) may be a so-called flat dome-shaped light source (10A) (see FIG. 2 (a)) or a dome-shaped light source (10B) (see FIG. 2 (b)). The light source (10A) shown in FIG. 2 (a) has 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 from the sample (100) and input into the camera system (20). With such a flat dome-shaped light source (10A), it is possible to secure a sufficient field of view (e.g., a field of view of about 300 mm) while suppressing overlapping phenomena. The light source (10B) has an LED (10e) and a dome portion (10f). Light irradiated from the LED (10e) is irradiated onto the inner surface of the dome portion (10f), diffused light from the inner surface of the dome portion (10f) is reflected from the sample (100), and the reflected light from the sample (100) is input into the camera system (20). The light source (10) may be a surface lighting unit using a white LED, a halogen lamp, or a Xe lamp, etc.

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

[0021] FIG. 3 is a diagram illustrating the relationship between the characteristics of an inclined dichroic mirror (22) and the wavelength of light emitted from a 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 characteristics (X4) of the inclined dichroic mirror (22) in FIG. 3, in the inclined dichroic mirror (22), the transmittance (and reflectance) of light changes gradually according to the change in wavelength in a predetermined wavelength range (X10), and in wavelength ranges other than that specific wavelength range, the transmittance (and reflectance) of light remains constant regardless of the change in wavelength. As shown in FIG. 3, the light (X20) output from the light source (10) contains light of a wavelength included in the aforementioned predetermined wavelength range (X10). That is, the light source (10) outputs light of a light spectrum that includes a predetermined wavelength range (X10). In addition, the wavelength range (interference peak wavelength) for measurement is determined by the material of the film formed on the sample (100) or the thickness range of the film being measured.

[0022] Returning to Fig. 1, the camera system (20) is configured to include a lens (21), an inclined dichroic mirror (22) (optical element), an area sensor (23, 24) (imaging unit), and a band-pass filter (25, 26).

[0023] The lens (21) is a lens that collects light from an incident sample (100). The lens (21) may be positioned upstream of the inclined dichroic mirror (22) or in the area between the inclined dichroic mirror (22) and the area sensors (23, 24). The lens (21) may be a finite focus lens or an infinite focus lens. If the lens (21) is a finite focus lens, the distance from the lens (21) to the area sensors (23, 24) is a predetermined value. If the lens (21) is an infinite focus lens, the lens (21) is a collimator lens that converts light from the sample (100) into parallel light, and is corrected for aberrations so that parallel light is 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 using a special optical material and is an optical element that separates light from a sample (100) by transmitting and reflecting it according to wavelength. The inclined dichroic mirror (22) is configured so that the transmittance and reflectance of light change according to wavelength in a predetermined wavelength range.

[0025] FIG. 4 is a diagram illustrating the spectrum of light and the characteristics of a slanted 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 the slanted dichroic mirror (22)). As shown in the characteristics (X4) of the slanted dichroic mirror (22) in FIG. 4, in the slanted dichroic mirror (22), the transmittance (and reflectance) of light changes gradually with changes in wavelength in a predetermined wavelength range (wavelength range of wavelengths λ1 to λ2), and in wavelength ranges other than the predetermined wavelength range (i.e., lower wavelength side than wavelength λ1 and higher wavelength side than wavelength λ2), the transmittance (and reflectance) of light remains constant regardless of changes in wavelength. In other words, in a specific wavelength range (wavelength range of wavelengths λ1 to λ2), the transmittance of light changes in a monotonically increasing manner (the reflectance changes in a monotonically decreasing manner) with changes in wavelength. Since transmittance and reflectance have a negative correlation in which a change in the direction of increasing one causes the other to change in the direction of decreasing, "transmittance (and reflectance)" may not be used below, but simply "transmittance." Furthermore, "transmittance of light is constant regardless of change in wavelength" includes not only cases where it is completely constant, but also cases where, for example, the change in transmittance for a change in wavelength of 1 nm is 0.1% or less. At wavelengths lower than λ1, the transmittance of light is generally 0% regardless of change in wavelength, and at wavelengths higher than λ2, the transmittance of light is generally 100% regardless of change in wavelength. Additionally, "transmittance of light is generally 0%" includes a transmittance of approximately 0% + 10%, and "transmittance of light is generally 100%" includes a transmittance of approximately 100% - 10%. In FIG. 4, the waveform (X1) represents the wavelength of 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 of a wavelength that is included in a predetermined wavelength range (wavelength range of wavelengths λ1 to λ2) of the inclined dichroic mirror (22).

[0026] Area sensors (23, 24) capture light separated by an inclined dichroic mirror (22). Area sensors (23) capture light transmitted from the inclined dichroic mirror (22). Area sensors (24) capture light reflected from the inclined dichroic mirror (22). The wavelength range to which the area sensors (23, 24) have sensitivity corresponds to a predetermined wavelength range in which the transmittance (and reflectance) of light changes according to the change in wavelength at the inclined dichroic mirror (22). Area sensors (23, 24) are, for example, monochrome sensors or color sensors. The capture result (image) by the area sensors (23, 24) is output to the control device (30).

[0027] A band pass filter (25) is positioned between the inclined dichroic mirror (22) and the area sensor (23). A band pass filter (26) is positioned between the inclined dichroic mirror (22) and the area sensor (24). The band pass filters (25, 26) may be filters that remove light in a wavelength range other than the predetermined wavelength range described above (a wavelength range in which the transmittance and reflectance of light change according to wavelength in the inclined dichroic mirror (22)).

[0028] Returning to FIG. 1, the control unit (30) is a computer and is physically configured to include 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 unit (30) functions by executing a program stored in memory on the CPU of the computer system. The control unit (30) may be configured as a microcomputer or an FPGA.

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

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

[0031] λ=λ0+A(TR) / 2(T+R) (1)

[0032] FIG. 5 is a diagram illustrating wavelength shift according to the amount of transmitted light and the amount of reflected light. When λ (wavelength center) is derived 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 (center wavelength of the inclined dichroic mirror (22)). Also, T <R인 화소, 즉 투과광량보다도 반사광량이 많은 화소에 대해서는, λ=λ1(λ0보다도 단파장측의 파장)으로 된다. 또한, T<R인 화소, 즉 투과광량보다도 반사광량이 많은 화소에 대해서는, λ=λ1(λ0보다도 단파장측의 파장)으로 된다. 또한, T> For pixels of R, that is, pixels where the amount of transmitted light is greater than the amount of reflected light, λ = λ2 (wavelength on the longer wavelength side than λ0). In this way, λ (wavelength center) is shifted (wavelength shifted) based on the amount of transmitted light and the amount of reflected light.

[0033] Furthermore, the method for deriving the center of gravity is not limited to the above. For example, since λ (center of gravity) is in a proportional relationship with x below, the center of gravity may be derived from equations (2) and (3) below. In equation (3) below, I T is the amount of transmitted light, I R ... indicates the amount of reflected light. In addition, if the spectral shape of the object being measured or the linearity of the inclined dichroic mirror (22) is an ideal shape, then the parameters a and b in equation (2) can be determined by the optical characteristics of the inclined dichroic mirror (22).

[0034] λ=ax+b (2)

[0035] x=I T -I R / 2( I T +I R ) (3)

[0036] In addition, since there are differences (individual differences) in the spectral characteristics between optical systems or cameras in practice, for the purpose of correcting them, for example, x may be derived by the following equation (4) by using the signal strength of a substrate with known reflection characteristics as a reference. In the following equation (4), I Tr is the transmitted light quantity at the reference, I Rr It represents the amount of reflected light at the reference.

[0037] x=( I T / I Tr -I R / I Rr ) / 2(I T / I Tr +I R / I Rr ) (4)

[0038] In addition, x may be derived by the following equation (5) using the signal quantity in an unreflective state for the purpose of eliminating the influence of direct light from the light source. In the following equation (5), I Tb is the amount of transmitted light in an anti-reflective state, I Rb It represents the amount of reflected light in a non-reflective state.

[0039] 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)

[0040] In addition, to comprehensively perform various corrections such as film characteristics, irradiation spectrum, and nonlinearity of the gradient dichroic mirror (22), the center of gravity (λ) may be approximated by a polynomial such as the following equation (6). In addition, each parameter (a, b, c, d, e) in the following equation (6) is determined, for example, by measuring multiple samples of different center of gravity (film thickness).

[0041] λ=ax 4 +bx 3 +cx 2+ dx+e (6)

[0042] Figure 6 is a diagram illustrating the principle of film thickness measurement. In Figure 6, the horizontal axis represents wavelength and the vertical axis represents reflectance. In the example shown in Figure 6, the relationship between wavelength and reflectance is shown for each example with a film thickness of 820 nm. As shown in Figure 6, the center of gravity of the wavelength differs depending on the difference in film thickness. Therefore, it becomes possible to estimate the film thickness by determining the center of gravity of the wavelength.

[0043] The relationship between wavelength and film thickness can be explained by the following equation (7), as shown in FIG. 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, …), and λ represents the center of gravity of the wavelength. 2nd represents 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 center of gravity of each pixel based on the following equation (7).

[0044] 2nd=mλ(m=1, 2, 3, …) (strong meeting condition)

[0045] 2nd=(m-1 / 2)(m=1, 2, 3, …) (weakly intersecting condition) (7)

[0046] Here, equation (7), which represents the relationship between the wavelength and the film thickness described above, holds true when light is incident perpendicularly on the sample (10). However, if light is not incident perpendicularly on the sample (100), equation (7) does not hold true. That is, as shown in FIG. 8, when light is incident on a sample (100) in which a film (101) is placed on the surface of a substrate (102), the angle of incidence of light and the optical path difference differ depending on the measurement point, so the film thickness cannot be estimated with high precision uniformly using equation (7). Therefore, in order to estimate the film thickness with high precision at any measurement point (angle of incidence), calculation (correction processing) according to the measurement point (angle of incidence) is required.

[0047] FIG. 9 is a diagram illustrating the correction of film thickness measurements. As shown in FIG. 9 (a), when the angle of incidence of light is θ, the optical path difference is represented as 2ndcosθ. By this, the relationship between the wavelength and film thickness considering the angle of incidence 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 (angle of incidence) based on the following equation (8). In this way, the control device (30) may estimate the film thickness from the center of gravity by further considering the angle of light irradiated onto the sample (100).

[0048] 2ndcosθ = mλ (strong intersection condition)

[0049] 2ndcosθ=(m-1 / 2)λ (weakly intersecting condition) (8)

[0050] As described above, the film thickness measuring device (1) performs a film thickness measuring method. The film thickness measuring method includes, for example, a first process of irradiating light in a planar shape onto a sample (100), a second process of capturing light separated by an inclined dichroic mirror (22) which separates light from the sample (100) by transmitting and reflecting it, and a third process of deriving a wavelength based on the capture result and estimating the film thickness of an object based on the corresponding wavelength.

[0051] Next, the effects of the present embodiment will be explained.

[0052] The film thickness measuring device (1) according to the present embodiment comprises a light source (10) that irradiates light in a planar shape onto a sample (100), an inclined dichroic mirror (22) that separates light from the sample (100) by transmitting and reflecting it, and an area sensor (23, 24) that captures 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 a signal from the area sensor (23, 24) that captured the light, and the light source (10) irradiates light of a wavelength included in the predetermined wavelength range of the inclined dichroic mirror (22).

[0053] In the film thickness measuring device (1) according to the present embodiment, light of a wavelength included in a predetermined wavelength range of the inclined dichroic mirror (22) is irradiated onto the sample (100) in a planar shape. Then, in the film thickness measuring device (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 transmittance and reflectance of the inclined dichroic mirror (22) change according to the wavelength in a predetermined wavelength range. Therefore, the ratio of transmitted light and the ratio of reflected light separated by the inclined dichroic mirror (22) change according to the wavelength. Then, as the separated light is captured by the area sensors (23, 24), the ratio of transmitted light and the ratio of reflected light can be determined, and as a result, the wavelength can be determined. In addition, the film thickness of the sample (100) is estimated by the control device (30) based on the signal from the area sensors (23, 24). Since the film thickness can be estimated based on information indicating the wavelength, as described above, the wavelength is determined from the image result from the area sensor (23, 24), and thus the film thickness of the sample (100) can be estimated with high precision by considering the signal containing the information of the corresponding wavelength (the signal from the area sensor (23, 24). Furthermore, in the film thickness measuring device (1) according to the present embodiment, light is irradiated in a planar shape onto the sample (100), and the film thickness within the planar surface of the sample (100) is simultaneously estimated according to the light from the sample (100). Therefore, compared to the case where the film thickness within the planar surface is estimated while the irradiation range of the light is changed by a point sensor or line scan, the film thickness distribution within the planar surface can be estimated at high speed. As described above, according to the film thickness measuring device (1) according to the present embodiment, the film thickness of the sample (100) can be measured at high speed.

[0054] FIG. 10 is a drawing showing the results of a comparison between a film thickness measuring device (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, a measurement time of about 4 hours is required. Also, the 4 hours mentioned here refers to the measurement time when, for example, about 16,000 points are detected. Also, as shown in FIG. 10, when the film thickness is measured one line at a time by a line scan, for example, a measurement time of about 3 minutes is required. In contrast to this, as shown in FIG. 10, in the film thickness measuring device (1) according to the present embodiment, light is irradiated in a planar shape onto the sample (100) and the film thickness within the planar area is measured collectively (simultaneously), so the measurement time is about 5 seconds. In this way, the film thickness measuring device (1) according to the present embodiment can estimate the film thickness distribution within the planar area at high speed by comparing it with a point sensor or line scan, etc., according to a comparative example. In addition, the film thickness measuring device (1) according to the present embodiment was able to reduce the error between the measurement result and the actual film thickness to 0.1% or less. Thus, the film thickness measuring device (1) according to the present embodiment can achieve both a reduction in the measurement time and an improvement in measurement precision regarding film thickness. Furthermore, since the configuration regarding the point sensor and line scan is difficult to mount in-line (on the device), the film thickness measuring device (1) according to the present embodiment can easily be mounted in-line.

[0055] In the above 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, 24). With this configuration, the film thickness distribution on the irradiated surface of the sample (100) can be estimated in more detail (for each pixel).

[0056] In the above film thickness measuring device (1), the control device (30) may estimate the film thickness by further considering the angle of light irradiated onto the sample (100). Since the light path changes when the angle of light irradiated onto the sample (100) changes, there are cases where the film thickness cannot be estimated with high precision from information only regarding wavelength. In this regard, by further considering the angle of light irradiated onto the sample (100), the film thickness can be estimated with higher precision according to the actual light path. Specifically, the film thickness is estimated using the above-described equation (8).

[0057] In the above film thickness measuring device (1), the light source (10) may irradiate diffuse light onto the sample (100). By doing so, light can be irradiated uniformly onto the surface of the sample (100).

[0058] In the above film thickness measuring device (1), the light source (10) may have a light guide plate (10d) (see FIG. 2 (a)) that generates diffused light. By doing so, light can be uniformly irradiated onto the surface of the sample (100) in a compact configuration.

[0059] The above film thickness measuring device (1) may further include a band-pass filter (25, 26) positioned between an inclined dichroic mirror (22) and area sensors (23, 24). By doing so, light outside the desired wavelength range can be removed, thereby improving the precision of film thickness estimation.

[0060] The film thickness measurement method according to the present embodiment comprises a first process of irradiating light in a planar shape onto a sample (100) by a film thickness measurement device (1), a second process of capturing light separated by an inclined dichroic mirror (22) that separates light from the sample (100) by transmitting and reflecting it, wherein the transmittance and reflectance change according to the wavelength in a predetermined wavelength range, and a third process of deriving a wavelength based on the capture result and estimating the film thickness of the sample (100) based on the corresponding wavelength. According to this film thickness measurement method, the film thickness of the sample (100) can be measured at high speed.

[0061] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The film thickness measuring device (1) can be applied to measuring the film thickness of various samples (100). As shown in FIG. 11, as samples (100), semiconductor devices (100A), flat panel displays (100B), film members (100C), electronic components (100D), and other components other than electronic components (100E) are considered.

[0062] That is, the film thickness measuring device (1) may measure the thickness of the film (101) formed on the substrate (102), which is a wafer, with respect to the semiconductor device (100A). In this case, as a device configuration, a wafer transport and holding mechanism including an arm, a cassette, a hoop, a conveyor, a moving stage, etc. is used.

[0063] Additionally, the film thickness measuring device (1) may measure the thickness of a film (101) formed on a substrate (102) composed of glass, film, sheet, etc., for a flat panel display (100B). In this case, a conveying and holding mechanism including an arm, a glass stand, a conveyor, a moving stage, etc. is used as the device configuration.

[0064] Additionally, the film thickness measuring device (1) may measure the thickness of a film (101) formed on a substrate (102) composed of glass, film, sheet, etc., with respect to a film member (100C). In this case, a conveying and holding mechanism including an arm, a glass stand, a conveyor, a moving stage, etc. is used as the device configuration. Additionally, with respect to the film member (100C), for example, as shown in FIG. 12, the film member (100C) being conveyed in one direction may be continuously imaged, and the imaged areas may be connected to each other so that the film thickness of the entire film member (100C) being conveyed may be measured.

[0065] Additionally, the film thickness measuring device (1) may measure the thickness of the film (101) formed on the substrate (102) with respect to the electronic component (100D). In this case, the device configuration may include a wafer transport and holding mechanism comprising an arm, a cassette, a hoop, a conveyor, a sample stand, a moving stage, etc.

[0066] Additionally, the film thickness measuring device (1) may measure the thickness of the film (101) formed on the substrate (102) with respect to the component (100E). The film of the component (100E) is, for example, a thin film such as a molded product, and in this case, the film thickness measurement is, for example, the measurement of the thin film coating thickness. As a device configuration, a wafer transport and holding mechanism including an arm, a cassette, a hoop, a conveyor, a sample stand, a moving stage, etc. is used.

[0067] In addition, the relative film thickness distribution is derived by the film thickness measurement described above, but in addition to this, the absolute value of the film thickness of each area may be derived based on the relative film thickness distribution and the reference spectrum information by detecting the spectrum information (reference spectrum information) of a point of the sample (100). FIG. 13 is a schematic diagram showing a film thickness measuring device (1A) according to a modified example. The film thickness measuring device (1A) is equipped with a half mirror (29) and a spectrometer (50) in addition to each component of the film thickness measuring device (1) described in the embodiment. The half mirror (29) reflects light from a point near the center of the sample (100), for example. The spectrometer (50) acquires reference spectrum information, which is the spectral spectrum data of the light at that point. In this way, by obtaining reference spectrum information, the value of m in equations (7) and (8) can be determined, and not only the relative change in film thickness but also the absolute value of the film thickness of each area can be derived. Furthermore, the method of measuring the absolute value of the film thickness is not limited to the above. Explanation of the symbols

[0068] 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 unit (analysis unit) 100: Sample (Object)

Claims

Claim 1 A film thickness measuring device comprising: a light irradiation unit that irradiates light in a planar shape onto an object; an optical element that separates light from the object by transmitting and reflecting it, wherein the transmittance and reflectance change monotonically according to the wavelength in a predetermined wavelength range; an imaging unit that captures 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 captured the light, wherein the light irradiation unit irradiates light of a wavelength included in the predetermined wavelength range of the optical element. Claim 2 A film thickness measuring device according to claim 1, wherein the interpretation unit estimates the film thickness corresponding to each pixel based on wavelength information for each pixel in the imaging unit. Claim 3 A film thickness measuring device according to claim 1, wherein the interpretation unit further considers the angle of light irradiated onto the object to estimate the film thickness. Claim 4 A film thickness measuring device according to any one of claims 1 to 3, wherein the light irradiation unit irradiates diffused light onto the object. Claim 5 A film thickness measuring device according to claim 4, wherein the light irradiation unit has a light guide plate that generates the diffused light. Claim 6 A film thickness measuring device according to claim 1, further comprising a band-pass filter disposed between the optical element and the imaging unit. Claim 7 A film thickness measurement method comprising: a first process of irradiating light in a planar shape onto an object; a second process of capturing light separated by an optical element that separates light from the object by transmitting and reflecting light, wherein the transmittance and reflectance change monotonically according to the wavelength in a predetermined wavelength range; and a third process of deriving a wavelength based on the capture result and estimating the film thickness of the object based on the wavelength.

Images