Film thickness measuring device and film thickness measuring method

Abstract

In this film thickness measurement device (1), a spectroscopic unit (5) performs wavelength decomposition on reference light (L1) and measurement light (L2) in a first direction (D1), and forms a spectroscopic image for each wavelength in a second direction (D2) intersecting the first direction (D1). The detection unit (6) has a first pixel region (21A) and a second pixel region (21B) which are divided in the second direction (D2), receives a spectral image (P1) of the reference light (L1) through the first pixel region (21A), and receives a spectral image (P2) of the measurement light (L2) through the second pixel region (21B).

Description

Technical Field

[0001] The present disclosure relates to a film thickness measuring device and a film thickness measuring method. Background Art

[0002] As a technique related to film thickness measurement, for example, there is a film thickness measuring device described in Patent Document 1. The film thickness measuring device includes: a measurement light source that supplies irradiation light to a measurement object; a spectroscopic detection unit that detects the intensity of the irradiation light and the intensity of the reflected light from the measurement object for each wavelength; a coefficient recording unit that records a conversion coefficient for converting a detection value of the intensity of each wavelength of the irradiation light into a value equivalent to the intensity of the reflected light of each wavelength from a reference measurement object; and a reflectance calculation unit that calculates the reflectance of each wavelength of the measurement object based on the detection value of the intensity of each wavelength of the irradiation light and the value equivalent to the intensity of the reflected light of each wavelength from the reference measurement object obtained by the conversion coefficient. Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-63321 Summary of the Invention Problems to be Solved by the Invention

[0004] In the film thickness measuring device as described above, it is considered to use a mechanical shutter to switch the optical path of the reference light (reference light) and the measurement light (measurement light) directed to the spectroscopic detection unit. However, when using a mechanical shutter, there are technical problems such as correction of the lack of synchronization in the detection of the reference light and the measurement light, ensuring maintainability, ensuring the sampling speed, and introducing a mechanism or optical system for adjusting the signal intensity. On the other hand, in recent years, in the film formation steps of various films such as optical films, films for display panels, and films for semiconductor wafers, the demand for on-line measurement of film thickness has been continuously increasing. To stably perform on-line measurement of film thickness, it is essential to solve the above technical problems.

[0005] The present disclosure is for solving the above problems, and an object thereof is to provide a film thickness measuring device and a film thickness measuring method capable of stably performing on-line measurement of film thickness. Technical Means for Solving the Problems

[0006] One embodiment of the film thickness measuring apparatus of the present disclosure includes: a spectroscopic unit that spectroscopically analyzes each of a reference light output from a light source and a measurement light output from the light source and reflected by a sample; a detection unit that detects a spectroscopic image of the reference light and a spectroscopic image of the measurement light spectroscopically analyzed by the spectroscopic unit; and an analysis unit that analyzes the film thickness of the sample based on reference data obtained from the detection result of the spectroscopic image of the reference light and measurement data obtained from the detection result of the spectroscopic image of the measurement light. The spectroscopic unit wavelength-disperses the reference light and the measurement light in a first direction, and images the spectroscopic image of each wavelength in a second direction intersecting the first direction. The detection unit has a first pixel region and a second pixel region divided in the second direction, receives the spectroscopic image of the reference light through the first pixel region, and receives the spectroscopic image of the measurement light through the second pixel region.

[0007] In this film thickness measuring apparatus, the reference light and the measurement light are wavelength-dispersed in the first direction, and the spectroscopic image of each wavelength is imaged in the second direction intersecting the first direction. In addition, the pixel region is divided in the second direction into a first pixel region and a second pixel region, the spectroscopic image of the reference light is received through the first pixel region, and the spectroscopic image of the measurement light is received through the second pixel region. Thereby, the synchronism of the detection of the reference light and the measurement light can be ensured, and correction can be easily performed even when the stability of the light source is low. In addition, there is no need for a mechanical movable part for switching the reference light and the measurement light, and the maintainability and the sampling speed can be sufficiently ensured. Furthermore, since the exposure times of the first pixel region and the second pixel region can be independently adjusted, even when measuring the film thickness of a sample with different reflection intensities, there is no need to introduce a mechanism or an optical system for adjusting the signal intensity. Therefore, in this film thickness measuring apparatus, the on-line measurement of the film thickness can be stably performed.

[0008] The detection unit may also be a CCD (Charge Coupled Device) photodetector. The CCD photodetector includes: a first horizontal shift register that transfers charges generated by each column of the first pixel region; and a second horizontal shift register that transfers charges generated by each column of the second pixel region. According to such a configuration, the reading of the charges corresponding to each pixel of the spectroscopic image of the reference light received in the first pixel region and the reading of the charges corresponding to each pixel of the spectroscopic image of the measurement light received in the second pixel region can be performed simultaneously. In addition, by using a CCD photodetector, an increase in reading noise when reading the charges generated by the pixels of each column can be avoided.

[0009] The detection unit may also be a CCD optical detector, which has: a first storage unit that stores charges generated by each column of the first pixel region; a second storage unit that stores charges generated by each column of the second pixel region; a first readout unit that outputs an electrical signal for each column corresponding to the magnitude of the charges stored by the first storage unit; and a second readout unit that outputs an electrical signal for each column corresponding to the magnitude of the charges stored by the second storage unit. With such a configuration, it is also possible to simultaneously perform the readout of the charges for each pixel corresponding to the spectral image of the reference light received in the first pixel region and the readout of the charges for each pixel corresponding to the spectral image of the measurement light received in the second pixel region. In addition, by using a CCD optical detector, an increase in readout noise when reading out the charges generated by the pixels of each column can be avoided.

[0010] The detection unit may also be a CMOS (Complementary Metal Oxide Semiconductor) optical detector, which has: a first readout unit that outputs charges generated by each column of the first pixel region; and a second readout unit that outputs charges generated by each column of the second pixel region. In such a configuration, it is also possible to simultaneously perform the readout of the charges for each pixel corresponding to the spectral image of the reference light received in the first pixel region and the readout of the charges for each pixel corresponding to the spectral image of the measurement light received in the second pixel region.

[0011] Alternatively, the film thickness measuring device may include: a first optical fiber that guides the reference light to the spectroscopic unit; a second optical fiber that guides the measurement light to the spectroscopic unit; and an optical fiber end that bundles the cores of the first optical fiber and the second optical fiber. The arrangement directions of the cores of the first optical fiber and the second optical fiber at the optical fiber end are the same as the extending direction of the slit on the input surface of the spectroscopic unit. With such a configuration, the spectral image of the reference light imaged in the first pixel region and the spectral image of the measurement light imaged in the second pixel region can be appropriately separated. Therefore, crosstalk between the reference light and the measurement light can be suppressed.

[0012] At the optical fiber end, a dummy core that physically separates the cores of the first optical fiber and the second optical fiber may be provided. In this case, the spectral image of the reference light imaged in the first pixel region and the spectral image of the measurement light imaged in the second pixel region can be more reliably separated. Therefore, crosstalk between the reference light and the measurement light can be further effectively suppressed.

[0013] Alternatively, it may be provided with a calculation unit that calculates a conversion coefficient for converting the detected value of the intensity of each wavelength of the reference light into a value equivalent to the intensity of each wavelength of the measurement light from the reference sample. The calculation unit calculates the conversion coefficient using the exposure time ratio between the first pixel region and the second pixel region. The analysis unit calculates the reflectance of each wavelength of the sample based on the detected value of the intensity of each wavelength of the reference light and the value equivalent to the intensity of each wavelength of the measurement light from the reference sample obtained by the conversion coefficient. In this case, when measuring the film thickness of the sample, without using the reference sample, based on the detected value of the intensity of each wavelength of the measurement light and the conversion coefficient, the value equivalent to the intensity of each wavelength of the measurement light from the reference sample can be calculated for each measurement. Therefore, even when the intensity of each wavelength of the measurement light fluctuates, the reflectance of each wavelength of the sample can be measured with high precision, and the accuracy of film thickness measurement is improved.

[0014] A film thickness measurement method according to an aspect of the present disclosure includes: a spectroscopic step of spectroscopically separating each of the reference light output from a light source and the measurement light output from the light source and reflected by a sample; a detection step of detecting the spectroscopic image of the reference light and the spectroscopic image of the measurement light spectroscopically separated in the spectroscopic step; and an analysis step of analyzing the film thickness of the sample based on reference data obtained from the detection result of the spectroscopic image of the reference light and measurement data obtained from the detection result of the spectroscopic image of the measurement light. In the spectroscopic step, the reference light and the measurement light are wavelength-dispersed in a first direction, and in a second direction intersecting the first direction, the spectroscopic image of each wavelength is imaged. In the detection step, using a first pixel region and a second pixel region divided in the second direction, the spectroscopic image of the reference light is received by the first pixel region, and the spectroscopic image of the measurement light is received by the second pixel region.

[0015] In this film thickness measurement method, the reference light and the measurement light are wavelength-dispersed in the first direction, and in the second direction intersecting the first direction, the spectroscopic image of each wavelength is imaged. In addition, the pixel region is divided in the second direction into a first pixel region and a second pixel region. The spectroscopic image of the reference light is received by the first pixel region, and the spectroscopic image of the measurement light is received by the second pixel region. Thereby, the synchronism of the detection of the reference light and the measurement light can be ensured, and correction can be easily performed even when the stability of the light source is low. In addition, there is no need for a mechanical movable part for switching the reference light and the measurement light, and the maintainability and sampling speed can be sufficiently ensured. Furthermore, since the exposure times of the first pixel region and the second pixel region can be independently adjusted, even when measuring the film thickness of samples with different reflection intensities, there is no need to introduce a mechanism or optical system for adjusting the signal intensity. Therefore, in this film thickness measurement method, on-line measurement of the film thickness can be stably performed. Effects of the Invention

[0016] According to the present disclosure, on-line measurement of the film thickness can be stably performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram showing a film thickness measuring device according to an embodiment of the present disclosure. Figure 2 (a) and (b) of are schematic diagrams showing the end face configurations of the first optical fiber and the second optical fiber. Figure 3 (a) and (b) of are schematic diagrams showing another example of the end face configurations of the first optical fiber and the second optical fiber. Figure 4 is a schematic diagram showing the imaging states of the spectral images of the reference light and the measurement light of the detection unit. Figure 5 is a schematic diagram showing the configuration of the slit on the input surface of the spectroscopic unit. Figure 6 is a diagram showing an example of the CCD photodetector constituting the detection unit. Figure 7 is a diagram showing another example of the CCD photodetector constituting the detection unit. Figure 8 is a diagram showing another example of the CCD photodetector constituting the detection unit. Figure 9 is a diagram showing an example of the CMOS photodetector constituting the detection unit. Figure 10 is a flowchart showing a film thickness measurement method according to an embodiment of the present disclosure. Figure 11 (a) to (e) of are schematic diagrams showing the situation of dark area subtraction correction. Figure 12 shows the use of Figure 1 is a flowchart showing an example of a film thickness measurement method using the film thickness measuring device shown. Figure 13 shows Figure 12 is a flowchart showing the subsequent steps of. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Hereinafter, while referring to the drawings, preferred embodiments of a film thickness measuring device and a film thickness measuring method according to an aspect of the present disclosure will be described in detail.

[0019] Figure 1 is a schematic diagram showing a film thickness measuring device according to an embodiment of the present disclosure. Figure 1The film thickness measuring device 1 shown, for example, constitutes a device for performing on-line measurement of the film thickness of a specimen M in a film forming step using a film forming chamber. As the specimen M, for example, an optical thin film, a thin film for a display panel, a thin film for a semiconductor wafer, etc. are cited. The film thickness measuring device 1 includes a light source 2, an optical system 3, a measuring head 4, a spectroscopic unit 5, a detection unit 6, a calculation unit 7, and an analysis unit 8.

[0020] The light source 2 is a device that outputs light L0 to the specimen M. As the light source 2, for example, a white light source that outputs light in a wavelength range of 185 nm or more and 2000 nm or less is used. As the light source 2, for example, a light source that outputs pulsed light with a repetition frequency of 1 kHz or more (e.g., a xenon flash lamp) is used. In the film thickness measuring device 1, the light L0 is used as a reference light L1 and a measurement light L2.

[0021] The optical system 3 is a system that guides the light L0, the reference light L1, and the measurement light L2 between the light source 2, the measuring head 4, and the spectroscopic unit 5. In the present embodiment, the optical system 3 has a first optical fiber 9A and a second optical fiber 9B. The first optical fiber 9A is an optical fiber that guides the reference light L1 to the spectroscopic unit 5. The second optical fiber 9B is an optical fiber that guides the measurement light L2 to the spectroscopic unit 5.

[0022] In the present embodiment, a branching coupler 10 is provided in the first optical fiber 9A. One end of the first optical fiber 9A branched by the coupler 10 is optically connected to the input end of the measuring head 4, and the other end is optically connected to the spectroscopic unit 5. One of the lights L0 output from the light source 2 is directly input to the spectroscopic unit 5 as the reference light L1, and the other of the lights L0 output from the light source 2 is input to the input end of the measuring head 4 as the measurement light L2.

[0023] The measuring head 4 is a part that irradiates the specimen M with the measurement light L2. The measuring head 4 is constituted by, for example, a half mirror and a condenser lens. The measurement light L2 input to the measuring head 4 from the other end of the first optical fiber 9A is irradiated to the specimen M via the half mirror and the condenser lens. The measurement light L2 reflected by the specimen M is input to the other end of the second optical fiber 9B from the output end of the measuring head 4 via the condenser lens and the half mirror.

[0024] The other end of the second optical fiber 9B is optically connected to the output end of the measuring head 4, and the other end is optically connected to the spectroscopic unit 5. The measurement light L2 output from the output end of the measuring head 4 is input to the spectroscopic unit 5 through the second optical fiber 9B. In the present embodiment, one end of the first optical fiber 9A and the other end of the second optical fiber 9B form an integrated optical fiber end 11. That is, the reference light L1 passing through the first optical fiber 9A and the measurement light L2 passing through the second optical fiber 9B are input to the spectroscopic unit 5 via the common optical fiber end 11.

[0025] In the optical fiber end 11, the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B are bundled.Figure 2 In (a), it is a configuration example when the cores 12A and 12B are single cores respectively. Figure 2 In the example of (a), in the end face 11a of the optical fiber end 11, the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B are linearly arranged sandwiching the center of the end face 11a. Figure 2 In (b), it is a configuration example when the cores 12A and 12B are optical fiber bundles respectively. Figure 2 In the example of (b), in the end face 11a of the optical fiber end 11, a plurality of cores 12A of the first optical fiber 9A and a plurality of cores 12B of the second optical fiber 9B are linearly arranged sandwiching the center of the end face 11a.

[0026] A dummy core 13 for physically separating the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B may be provided at the optical fiber end 11. Figure 3 In the example of (a), in the end face 11a of the optical fiber end 11, the dummy core 13 is located at the center of the end face 11a of the optical fiber end 11, and the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B are linearly arranged sandwiching the dummy core 13. Figure 3 In the example of (b), in the end face 11a of the optical fiber end 11, the dummy core 13 is located at the center of the end face 11a of the optical fiber end 11, and a plurality of cores 12A of the first optical fiber 9A and a plurality of cores 12B of the second optical fiber 9B are linearly arranged sandwiching the dummy core 13.

[0027] The diameter of the dummy core 13 is not particularly limited. Figure 2 In the examples of (a) and Figure 2 (b), the diameter of the dummy core 13 is smaller than the core diameter of the single-core first optical fiber 9A and the core diameter of the second optical fiber 9B. In addition, Figure 3 In the examples of (a) and Figure 3 (b), the diameter of the dummy core 13 is the same as the core diameters of the optical fiber bundles, that is, the core diameters of the first optical fiber 9A and the second optical fiber 9B.

[0028] The spectroscopic unit 5 is a part for spectroscopically separating each of the reference light L1 output from the light source 2 and the measurement light L2 output from the light source 2 and reflected by the specimen M. As the spectroscopic unit 5, a spectroscope with good imaging properties is used. As the spectroscope constituting the spectroscopic unit 5, for example, a Czerny-Turner type spectroscope, a Dyson type spectroscope, an Offner type spectroscope, etc. that can correct astigmatism and aberration are listed.

[0029] The spectroscopic unit 5, for example, as shown in Figure 4 , wavelength-disperses the reference light L1 and the measurement light L2 in the first direction D1, and images the spectroscopic images P1 and P2 of each wavelength in the second direction D2 intersecting the first direction D1. Here, the first direction D1 and the second direction D2 are orthogonal to each other. Figure 4In the example, the first direction D1 is along the row direction of the pixel region 21 constituting the detection unit 6, and the second direction D2 is along the column direction of the pixel region 21.

[0030] On the input surface 5a of the spectroscopic unit 5, as Figure 5 shown, a slit 14 is provided opposite to the end face 11a of the optical fiber end 11. The extending direction of the slit 14 is the same as the arrangement direction of the cores 12A of the first optical fiber 9A and the cores 12B of the second optical fiber 9B on the end face 11a of the optical fiber end 11. In addition, the center of the extending direction of the slit 14 is opposite to the center of the end face 11a of the optical fiber end 11. Therefore, a half portion of the slit 14 opposite to the core 12A of the first optical fiber 9A becomes the region 14A for inputting the reference light L1, and a half portion of the slit 14 opposite to the core 12B of the second optical fiber 9B becomes the region 14B for inputting the measurement light L2.

[0031] The detection unit 6 is a part for detecting the spectral image P1 of the reference light L1 and the spectral image P2 of the measurement light L2 spectroscopically separated by the spectroscopic unit 5. As Figure 4 shown, the detection unit 6 has a pixel region 21 for photographing the spectral images P1 and P2. In the pixel region 21, a plurality of pixels 22 are arranged in the row direction and the column direction. Figure 4 In the example, the row direction corresponding to the first direction D1 is along the wavelength dispersion direction of the spectral images P1 and P2 of the spectroscopic unit 5, and the column direction corresponding to the second direction D2 is along the charge transfer direction of each pixel 22. Each pixel 22 receives the wavelength-dispersed spectral images P1 and P2 and generates and accumulates charges corresponding to the light intensity.

[0032] Figure 4 In the example, the pixel region 21 is formed into a horizontally long rectangular region in which the number of pixels in the row direction is larger than the number of pixels in the column direction. The pixel region 21 has a first pixel region 21A and a second pixel region 21B divided in the second direction D2. Here, the division between the first pixel region 21A and the second pixel region 21B is made at the center in the column direction. That is, in the pixel region 21, the pixels 22 closer to one side than the center in the column direction belong to the first pixel region 21A, and the pixels 22 closer to the other side than the center in the column direction belong to the second pixel region 21B.

[0033] The first exposure time T1 of each pixel 22 in the first pixel region 21A and the second exposure time T2 of each pixel 22 in the second pixel region 21B can be set independently of each other. The exposure time ratio T2 / T1 between the first pixel region 21A and the second pixel region 21B is set according to the type of the film of the specimen M, etc. In the present embodiment, the first exposure time T1 of the first pixel region 21A for detecting the spectral image P1 of the reference light L1 is set to be constant, and the second exposure time T2 of the second pixel region 21B for detecting the spectral image P2 of the measurement light L2 is adjusted according to the type of the film of the specimen M, etc.

[0034] The exposure times T1 and T2 are set based on the reflection intensity or reflectance of the measurement light L2 of the specimen M. For example, when the reflection intensity or reflectance of the measurement light L2 of the specimen M is small, it is only necessary to increase the second exposure time T2 of each pixel 22 in the second pixel region 21B. Thereby, the S / N ratio of the detection of the spectral image P1 with respect to the reference light L1 and the S / N ratio of the detection of the spectral image with respect to the measurement light L2 can be matched to the same level. From the viewpoint of sufficiently ensuring the S / N ratio of the detection of the spectral image with respect to the measurement light L2, as an example, the second exposure time T2 is set such that the peak intensity of the spectral data (measurement data Ssig described later) of the measurement light L2 becomes 80% or more and less than 100% of the saturation intensity in the second pixel region 21B.

[0035] In the present embodiment, as described above, in the slit 14 on the input surface 5a of the spectroscopic unit 5, the half portion opposite to the core 12A of the first optical fiber 9A becomes the region 14A for inputting the reference light L1, and the half portion opposite to the core 12B of the second optical fiber 9B in the slit 14 becomes the region 14B for inputting the measurement light L2. Therefore, in the spectroscopic unit 5, the optical path of the reference light L1 and the optical path of the measurement light L2 are spatially separated, and in the pixel region 21, the spectral image P1 of the reference light L1 and the spectral image P2 of the measurement light L2 are separated in the column direction.

[0036] Figure 4 In the example of, five spectral images P1 of the reference light L1 wavelength-dispersed by the spectroscopic unit 5 are imaged on the first pixel region 21A. In addition, five spectral images P2 of the measurement light L2 wavelength-dispersed by the spectroscopic unit 5 are imaged on the second pixel region 21B in the same imaging timing as the spectral image P1 in the first pixel region 21A. Each of the spectral images P1 and P2 is imaged on the first pixel region 21A and the second pixel region 21B, respectively, in a state of linearly extending in the column direction of the pixel 22 and being separated from each other in the row direction. The detection unit 6 generates spectroscopic data corresponding to each of these spectral images P1 and P2 and outputs them to the analysis unit 8.

[0037] The detection unit 6 can be constituted by, for example, a CCD photodetector or a CMOS photodetector. Figure 6 FIG. is a diagram showing an example of a CCD photodetector constituting the detection unit. Figure 6 The CCD photodetector V1 shown is configured to include: a pixel region 21 including the first pixel region 21A and the second pixel region 21B described above; a first horizontal shift register 32A corresponding to the first pixel region 21A; a second horizontal shift register 32B corresponding to the second pixel region 21B; and a plurality of dummy pixels 33.

[0038] The charges generated and accumulated by the respective pixels 22 of the first pixel region 21A are transferred to the first horizontal shift register 32A. At the time of transfer, the charges of the pixels 22 in each column are added for each column in the first horizontal shift register 32A (vertical transfer), and the charges added for each column are sequentially read out from the first horizontal shift register 32A (horizontal transfer). A voltage value corresponding to the amount of charge read out from the first horizontal shift register 32A is output from the amplifier 34A. The voltage value output from the amplifier 34A is converted into a digital value by an AD (Analog-Digital) converter. Thus, spectral data (reference data Sref) of the detection result of the spectral image P1 based on the reference light L1 is obtained.

[0039] The charges generated and accumulated by the respective pixels 22 of the second pixel region 21B are transferred to the second horizontal shift register 32B. At the time of transfer, the charges of the pixels 22 in each column are added for each column in the second horizontal shift register 32B (vertical transfer), and the charges added for each column are sequentially read out from the second horizontal shift register 32B (horizontal transfer). A voltage value corresponding to the amount of charge read out from the second horizontal shift register 32B is output from the amplifier 34B. The voltage value output from the amplifier 34B is converted into a digital value by the AD converter. Thus, spectral data (measurement data Ssig) of the detection result of the spectral image P2 based on the measurement light L2 is obtained.

[0040] In the CCD photodetector V1, the first exposure time T1 of the first pixel region 21A and the second exposure time T2 of the second pixel region 21B can be set by an electronic shutter, for example. The electronic shutter can be realized by using an anti-blooming gate, for example. The output operation of the reference data Sref and the output operation of the measurement data Ssig are independently controlled, but preferably synchronized with each other. In this case, it is possible to prevent a signal indicating one output operation from being repeated as noise for the output signal of the other output operation.

[0041] Figure 7 and Figure 8 FIG. is a diagram showing another example of the CCD photodetector constituting the detection unit. Figure 7 and Figure 8 The CCD photodetector V2 shown has: a conversion substrate 40; a first storage unit 41A that stores charges generated by each column of the first pixel region 21A; a second storage unit 41B that stores charges generated by each column of the second pixel region 21B; a first readout unit 42A that outputs column electric signals corresponding to the magnitude of the charges stored in the first storage unit 41A; and a second readout unit 42B that outputs column electric signals corresponding to the magnitude of the charges stored in the second storage unit 41B.

[0042] The conversion substrate 40 is arranged on the pixel region 21 side in the column direction. A voltage signal (driving signal) for controlling the charge transfer of the pixels 22 is supplied to the conversion substrate 40. The charges of the pixels 22 in each column belonging to the first pixel region 21A are transferred to the first storage section 41A in each column based on the voltage signal supplied to the conversion substrate 40. The charges of the pixels 22 in each column belonging to the second pixel region 21B are transferred to the second storage section 41B in each column based on the voltage signal supplied to the conversion substrate 40.

[0043] The first storage section 41A is arranged at the end in the column direction of the first pixel region 21A for each column, and stores the charges generated by the pixels 22 in each column of the first pixel region 21A. The second storage section 41B is arranged at the end in the column direction of the second pixel region 21B for each column, and stores the charges generated by the pixels 22 in each column of the second pixel region 21B. The first readout section 42A is arranged at the end in the column direction of the first pixel region 21A, behind the first storage section 41A, and the second readout section 42B is arranged at the end in the column direction of the second pixel region 21B, behind the second storage section 41B.

[0044] The first readout section 42A, as Figure 7 shown, for example, has a transistor 43A and a signal output bonding pad 44A. The control terminal (gate) of the transistor 43A is electrically connected to the first storage section 41A. One current terminal (drain) of the transistor 43A is electrically connected to the bonding pad 46A via a wiring 45A provided in common for each column of the first pixel region 21A. A voltage of a specified magnitude is always applied to the bonding pad 46A.

[0045] The other current terminal (source) of the transistor 43A is electrically connected to the signal output bonding pad 44A. A voltage corresponding to the first electrical signal output from the first storage section 41A is applied to the control terminal of the transistor 43A. A current corresponding to the applied voltage is output from the other current terminal of the transistor 43A and taken out to the outside via the signal output bonding pad 44A.

[0046] The second readout section 42B, as Figure 8 shown, for example, has a transistor 43B and a signal output bonding pad 44B. The control terminal (gate) of the transistor 43B is electrically connected to the second storage section 41B. One current terminal (drain) of the transistor 43B is electrically connected to the bonding pad 46B via a wiring 45B provided in common for each column of the second pixel region 21B. A voltage of a specified magnitude is always applied to the bonding pad 46B.

[0047] Another current terminal (source) of the transistor 43B is electrically connected to the signal output bonding pad 44B. A voltage corresponding to the second electrical signal output from the second storage unit 41B is applied to the control terminal of the transistor 43B. A current corresponding to the applied voltage is output from the another current terminal of the transistor 43B and taken out to the outside via the signal output bonding pad 44B.

[0048] Figure 9 FIG. is a diagram showing an example of a CMOS photodetector constituting the detection unit. In the CMOS photodetector V3 shown in the figure, each pixel 22 constituting the pixel region 21 has a photodiode 51 and an amplifier 52. The photodiode 51 accumulates electrons (photoelectrons) generated by light input as charges. The amplifier 52 converts the charges accumulated in the photodiode 51 into an electrical signal and amplifies the converted signal.

[0049] The electrical signal amplified by the amplifier 52 is transmitted to the vertical signal line 54 connecting the pixels 22 in the row direction by switching the selection switch 53 of each pixel 22. In each of the vertical signal lines 54, a CDS (correlated double sampling) circuit 55 is arranged. The CDS circuit 55 reduces the readout noise between the pixels 22 and temporarily stores the electrical signal transmitted to the vertical signal line 54. The CDS circuit 55 is electrically connected to the conversion unit 56. The conversion unit 56 converts the voltage value output from the amplifier 52 of each pixel 22 into a digital value. In the present embodiment, the conversion unit 56 is constituted by an A / D converter. The A / D converter converts the voltage value stored in the CDS circuit 55 into a digital value (pixel value).

[0050] The CMOS photodetector V3 has: a first readout unit 57A that outputs charges generated by each column of the first pixel region 21A; and a second readout unit 57B that outputs charges generated by each column of the second pixel region 21B. The first readout unit 57A is connected to an A / D converter corresponding to the vertical signal line 54 of each pixel 22 belonging to the first pixel region 21A. The first readout unit 57A outputs the pixel values of each pixel 22 belonging to the first pixel region 21A. The second readout unit 57B is connected to an A / D converter corresponding to the vertical signal line 54 of each pixel 22 belonging to the second pixel region 21B. The second readout unit 57B outputs the pixel values of each pixel 22 belonging to the second pixel region 21B.

[0051] The calculation unit 7 and the analysis unit 8 are physically constituted by, for example, a computer 9 having a processor such as a CPU (Central Processing Unit), a storage medium such as a RAM (Random Access Memory), and a ROM (Read only Memory). The computer 9 may also be a smart phone or a tablet terminal that integrally includes a display unit or an input unit. The computer 9 may also be constituted by a microcomputer or an FPGA (Field-Programmable Gate Array).

[0052] The calculation unit 7 is a part that calculates a conversion coefficient K for converting a detection value of the intensity of each wavelength of the reference light L1 into a value equivalent to the intensity of each wavelength of the measurement light L2 from the reference sample. The conversion coefficient K is a coefficient for correcting the reference light L1. Specifically, the conversion coefficient K is a coefficient for calculating, for each measurement, a value equivalent to the intensity of each wavelength of the measurement light L2 from the reference sample without using the reference sample when measuring the film thickness of the sample M. The conversion coefficient K is calculated using the exposure time ratio T2 / T1 between the first pixel region 21A and the second pixel region 21B. Details will be described below.

[0053] The analysis unit 8 is based on the reference data S obtained from the detection result of the spectral image P1 of the reference light L1 ref and the measurement data S obtained from the detection result of the spectral image P2 of the measurement light L2 sig , and is a part for analyzing the film thickness of the sample M. The analysis unit 8 calculates the reflectance of each wavelength of the sample M based on the reference data S ref and the measurement data S sig , and analyzes the film thickness of the sample M based on the calculation result. In the present embodiment, for the film thickness analysis of the sample M, the spectral reflectance data R of the sample M is used sig . The above conversion coefficient K is used for the calculation of the spectral reflectance R sig .

[0054] Next, a film thickness measurement method according to an embodiment of the present disclosure will be described. Figure 10 is a flowchart showing a film thickness measurement method according to an embodiment of the present disclosure. As Figure 10 shown, the film thickness measurement method is configured to include a calculation step S01, a spectral analysis step S02, a detection step S03, and an analysis step S04.

[0055] The calculation step S01 is a step of calculating the conversion coefficient K used in the analysis step S04. The spectroscopic step S02 is a step of spectroscopically separating each of the reference light L1 output from the light source 2 and the measurement light L2 output from the light source 2 and reflected by the sample M. The detection step S03 is a step of detecting the spectral image P1 of the reference light L1 and the spectral image P2 of the measurement light L2 spectroscopically separated by the spectroscopic step S02. The analysis step S04 is a step of analyzing the film thickness of the sample M based on the reference data S obtained from the detection result of the spectral image P1 of the reference light L1 ref and the measurement data S obtained from the detection result of the spectral image P2 of the measurement light L2 sig .

[0056] In the present embodiment, the film thickness measuring method including steps S01 to S04 is implemented using the above-described film thickness measuring device 1. Here, a method is exemplified in which the dark area operation correction of the film thickness measuring device 1 is first implemented, and then the film thickness measurement of the sample M is implemented

[0057] In the detection unit 6, there is a case where a weak signal is output even when there is no input of the reference light L1 and the measurement light L2. This weak signal is also referred to as dark current. The use of the dark current is that correction is required when detecting the light intensity by the detection unit 6. In addition to the dark current, the signal output from the detection unit 6 may also include a signal caused by interfering light such as light irradiated from indoor lighting (hereinafter, these are collectively referred to as dark signals). Therefore, in the film thickness measuring device 1, in order to accurately obtain the reference data S based on the spectral image P1 of the reference light L1 ref and the measurement data S based on the spectral image P2 of the measurement light L2 sig , it is necessary to subtract the spectral data of the dark signal from the spectral data of the spectroscopic spectrum corresponding to each of the spectral images P1 and P2

[0058] Figure 11 (a) to (e) of are schematic views showing the state of the dark area correction operation. In the dark area correction operation, first, in a state where the output of the light source 2 is turned off, the spectral data of the dark signal is obtained by the detection unit 6. The spectral data of the dark signal is, for example Figure 11 as shown in (a) of, includes a white noise component and a noise component having a peak in a specific wavelength region. The white noise component is the noise component of the dark current (see Figure 11 (b) of ). The noise component having a peak in a specific wavelength region is the noise component caused by interfering light (see Figure 11 (c) of ).

[0059] Next, in a state where the output of the light source 2 is turned on, the spectral data of the reference light L1 is obtained by the detection unit 6. This spectral data is, for example Figure 11 as shown in (d) of, and the spectral data of the dark signal is added to the spectral data of the reference light L1. By subtracting fromFigure 11 Subtract the waveform of (d) from Figure 11 the spectral data of the dark signal shown in (a) to obtain the spectral data of the reference light L1 excluding the influence of the dark signal (see Figure 11 (e)). By performing the same process on the measurement light L2, the spectral data of the measurement light L2 excluding the influence of the dark signal is obtained.

[0060] Figure 12 It shows the use of Figure 1 A flowchart showing an example of a film thickness measurement method using the film thickness measurement device shown. In addition, Figure 13 It shows Figure 12 The flowchart of the subsequent steps. As Figure 12 shown, in this film thickness measurement method, first, a reference sample (not shown) with known spectral reflectance data is prepared (step S11), and the measurement head 4 is arranged for this reference sample. Then, the light source 2 is turned on, and the reference light L1 and the measurement light L2 are output from the light source 2 (step S12). Here, for the convenience of distinguishing the reference light L1 and the measurement light L2 for measuring the film thickness of the sample M, the reference light L1 and the measurement light L2 for the reference sample are respectively called the correction reference light L1' and the correction measurement light L2'.

[0061] The correction reference light L1' is wavelength-dispersed by the spectroscopic unit 5, and the spectroscopic image is detected in the first pixel region 21A of the detection unit 6, thereby obtaining and recording the spectral data of the correction reference light L1' (correction reference data C ref )(step S12). In addition, the correction measurement light L2' is wavelength-dispersed by the spectroscopic unit 5, and the spectroscopic image is detected in the second pixel region 21B of the detection unit 6, thereby obtaining and recording the spectral data of the correction measurement light L2' (correction measurement data C sig )(step S13).

[0062] The pixel region 21 of the detection unit 6 is divided into the first pixel region 21A and the second pixel region 21B (see Figure 4 ). Therefore, the correction reference data C ref and the correction measurement data C sig are obtained in the same time sequence (that is, step S12 and step S13 are implemented simultaneously). The first exposure time T1 of the first pixel region 21A when detecting the spectroscopic image of the correction reference light L1' and the second exposure time T2 of the second pixel region 21B when detecting the spectroscopic image of the correction measurement light L2' are set to be equal to each other. The recording of the correction reference data C ref and the correction measurement data C sig is performed by the calculation unit 7.

[0063] Obtain the correction reference data C refand measurement data C for correction sig After that, the light source 2 is turned off (step S15). After turning off the light source 2, spectral data of the dark signal output from the first pixel region 21A of the self-detection unit 6 is acquired and recorded (first correction dark signal data D ref )(step S16). In addition, spectral data of the dark signal output from the second pixel region 21B of the self-detection unit 6 is acquired and recorded (second correction dark signal data D sig )(step S17).

[0064] The first correction dark signal data D ref and the second correction dark signal data D sig are acquired at the same time sequence as when acquiring the correction reference data C ref and the measurement data C for correction sig (that is, steps S16 and S17 are carried out simultaneously). The recording of the first correction dark signal data D ref and the second correction dark signal data D sig is performed by the calculation unit 7.

[0065] Next, as Figure 13 shown, a specimen M to be the measurement object of the film thickness is prepared (step S21), and the measurement head 4 is arranged for the specimen M. After arranging the measurement head 4, the first exposure time T1 of the first pixel region 21A and the second exposure time T2 of the second pixel region 21B are respectively set (step S22). In this embodiment, regardless of the type of the specimen M, the first exposure time T1 is set to be constant. On the other hand, the second exposure time T2 is set for each specimen M in such a manner that the peak intensity of the measurement data S sig becomes 80% or more and less than 100% of the saturation intensity in the second pixel region 21B.

[0066] After setting the exposure times T1 and T2, in the calculation unit 7, a conversion coefficient K is calculated (step S23: calculation step). The conversion coefficient K is a coefficient for converting the detected value of the intensity of each wavelength of the reference light L1 into a value equivalent to the intensity of each wavelength of the measurement light L2 from the reference specimen. The conversion coefficient K is calculated from the following formula (1) using the correction reference data C ref , the measurement data C for correction sig , the first correction dark signal data D ref , the second correction dark signal data D sig , the reflectance data R Ref (λ) of the reference specimen and the exposure time ratio T2 / T1. The calculated conversion coefficient K is recorded in the calculation unit 7. K = (C sig - D sig ) / (R ref (λ) × (Cref -D ref )×(T2 / T1))…(1)

[0067] After calculating the conversion coefficient K, turn on the light source 2, and output the reference light L1 and the measurement light L2 from the light source 2 (step S24). Perform wavelength decomposition on the reference light L1 through the spectroscopic unit 5, and detect the spectroscopic image P in the first pixel region 21A of the detection unit 6 with the first exposure time T1, thereby obtaining and recording the spectral data of the reference light L1 (reference data S ref )(step S25: spectroscopic step / detection step). In addition, perform wavelength decomposition on the measurement light L2 through the spectroscopic unit 5, and detect the spectroscopic image P in the second pixel region 21B of the detection unit 6 with the second exposure time T2, thereby obtaining and recording the spectral data of the measurement light L2 (measurement data S sig )(step S26: spectroscopic step / detection step).

[0068] Similar to the case of obtaining the correction reference data C ref and the correction measurement data C sig , the reference data S ref and the measurement data S sig are obtained at the same time sequence (that is, steps S12 and S13 are implemented simultaneously). The recording of the reference data S ref and the measurement data S sig is performed by the analysis unit 8.

[0069] After obtaining the reference data S ref and the measurement data S sig , turn off the light source 2 (step S27). After turning off the light source 2, obtain and record the spectral data of the dark signal output from the first pixel region 21A of the detection unit 6 (the first dark signal data D' ref )(step S28). In addition, obtain and record the spectral data of the dark signal output from the second pixel region 21B of the detection unit 6 (the second dark signal data D' sig )(step S29).

[0070] The first dark signal data D' ref and the second dark signal data D' sig are obtained at the same time sequence as the case of obtaining the reference data S ref and the measurement data S sig (that is, steps S28 and S29 are implemented simultaneously). The recording of the first dark signal data D' ref and the second dark signal data D' sig is performed by the analysis unit 8.

[0071] After obtaining the reference data S ref and the measurement data S sig, and obtaining the first dark signal data D' ref and the second dark signal data D' sig After that, in the analysis unit 8, the spectral reflectance data R of the sample M is calculated sig (Step S30: Analysis step). The spectral reflectance data R sig uses the reference data S ref , the measurement data S sig , the first dark signal data D' ref , the second dark signal data D' sig and the conversion coefficient K, and is calculated by the following formula (2). In the analysis unit 8, based on the calculated spectral reflectance data R sig , the film thickness of the sample M is calculated (Step S31: Analysis step). R sig =(S sig -D' sig ) / ((S ref -D' ref )×K)…(2)

[0072] As described above, in the film thickness measuring device 1 and the film thickness measuring method of the present embodiment, the reference light L1 and the measurement light L2 are wavelength-dispersed in the first direction D1, and in the second direction D2 intersecting the first direction D1, the spectral images of each wavelength are imaged. In addition, the pixel region 21 is divided in the second direction D2 into a first pixel region 21A and a second pixel region 21B. The spectral image P1 of the reference light L1 is received through the first pixel region 21A, and the spectral image P2 of the measurement light L2 is received through the second pixel region 21B.

[0073] Thereby, the synchronization of the detection of the reference light L1 and the measurement light L2 can be ensured, and correction can be easily performed even when the stability of the light source 2 is low. In addition, there is no need for a mechanical movable part for switching the reference light L1 and the measurement light L2, and the maintainability and sampling speed can be fully ensured. Furthermore, since the exposure times T1 and T2 of the first pixel region 21A and the second pixel region 21B can be independently adjusted, even when measuring the film thickness of a sample M with different reflection intensities, there is no need to introduce a mechanism or optical system for adjusting the signal intensity. Therefore, in the film thickness measuring device 1 and the film thickness measuring method, the on-line measurement of the film thickness can be stably performed.

[0074] In this embodiment, the detection unit 6 may be constituted by a CCD photodetector V1. The CCD photodetector V1 includes: a first horizontal shift register 32A that transfers charges generated by respective columns of the first pixel region 21A; and a second horizontal shift register 32B that transfers charges generated by respective columns of the second pixel region 21B. With such a configuration, it is possible to simultaneously perform the reading of charges of respective pixels 22 of the spectral image P1 corresponding to the reference light L1 received in the first pixel region 21A and the reading of charges of respective pixels 22 of the spectral image P2 corresponding to the measurement light L2 received in the second pixel region 21B. In addition, by using the CCD photodetector V1, an increase in read noise when reading charges generated by the pixels 22 of respective columns can be avoided.

[0075] In this embodiment, the detection unit 6 may be constituted by a CCD photodetector V2. The CCD photodetector V2 includes: a first storage unit 41A that stores charges generated by respective columns of the first pixel region 21A; a second storage unit 41B that stores charges generated by respective columns of the second pixel region 21B; a first reading unit 42A that outputs electrical signals of respective columns corresponding to the magnitudes of the charges stored in the first storage unit 41A; and a second reading unit 42B that outputs electrical signals of respective columns corresponding to the magnitudes of the charges stored in the second storage unit 41B. In such a configuration, it is also possible to simultaneously perform the reading of charges of respective pixels 22 of the spectral image P1 corresponding to the reference light L1 received in the first pixel region 21A and the reading of charges of respective pixels 22 of the spectral image P2 corresponding to the measurement light L2 received in the second pixel region 21B. In addition, by using the CCD photodetector V2, an increase in read noise when reading charges generated by the pixels of respective columns can be avoided.

[0076] In this embodiment, the detection unit 6 may be constituted by a CMOS photodetector V3. The CMOS photodetector V3 includes: a first reading unit 57A that outputs charges generated by respective columns of the first pixel region 21A; and a second reading unit 57B that outputs charges generated by respective columns of the second pixel region 21B. In such a configuration, it is also possible to simultaneously perform the reading of charges of respective pixels 22 of the spectral image P1 corresponding to the reference light L1 received in the first pixel region 21A and the reading of charges of respective pixels 22 of the spectral image P2 corresponding to the measurement light L2 received in the second pixel region 21B.

[0077] In this embodiment, like the CCD photodetectors V1, CCD photodetectors V2, and CMOS photodetector V3 described above, the pixel region 21 of a single sensor is divided into a first pixel region 21A and a second pixel region 21B, and the reference light L1 and the measurement light L2 are detected. With such a configuration, compared to the case where two sensors are used to detect the reference light L1 and the measurement light L2 respectively, only a single control circuit is required, so the hardware configuration of the film thickness measuring device 1 can be simplified. In addition, since the first pixel region 21A and the second pixel region 21B are spatially close to each other, the optical design of the optical system 3 and the spectroscopic unit 5 can also be prevented from becoming complicated. Furthermore, since the thermal or optical drift between the first pixel region 21A and the second pixel region 21B can be shared, it is easy to eliminate the influence of drift in the design.

[0078] In this embodiment, the film thickness measuring device 1 includes: a first optical fiber 9A that guides the reference light L1 to the spectroscopic unit 5; a second optical fiber 9B that guides the measurement light L2 to the spectroscopic unit 5; and an optical fiber end 11 that bundles the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B. Moreover, the arrangement directions of the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B at the optical fiber end 11 are the same as the extending direction of the slit 14 on the input surface 5a of the spectroscopic unit 5. With such a configuration, the spectroscopic image P1 of the reference light L1 formed on the first pixel region 21A and the spectroscopic image P2 of the measurement light L2 formed on the second pixel region 21B can be appropriately separated. Therefore, crosstalk between the reference light L1 and the measurement light L2 can be suppressed.

[0079] In this embodiment, a configuration can be adopted in which a dummy core 13 that physically separates the core 12A of the first optical fiber 9A and the core 12B of the second optical fiber 9B is provided in the optical fiber end 11. In this case, the spectroscopic image P1 of the reference light L1 formed on the first pixel region 21A and the spectroscopic image P2 of the measurement light L2 formed on the second pixel region 21B can be more reliably separated. Therefore, crosstalk between the reference light L1 and the measurement light L2 can be further effectively suppressed.

[0080] In this embodiment, the film thickness measuring apparatus 1 includes a calculation unit 7 that calculates a conversion coefficient K for converting a detected value of the intensity of each wavelength of the reference light L1 into a value of the intensity of each wavelength of the measurement light L2 (correction-use measurement light L2') equivalent to that from a reference sample. The calculation unit 7 calculates the conversion coefficient K using the exposure time ratio T2 / T1 between the first pixel region 21A and the second pixel region 21B. Further, an analysis unit 8 calculates the reflectance of each wavelength of the sample M based on the detected value of the intensity of each wavelength of the reference light L1 and the value of the intensity of each wavelength of the measurement light L2 equivalent to that from the reference sample obtained by the conversion coefficient K. Thus, when measuring the film thickness of the sample M, it is possible to calculate, for each measurement, a value of the intensity of each wavelength of the correction-use measurement light L2' equivalent to that from the reference sample based on the detected value of the intensity of each wavelength of the measurement light L2 and the conversion coefficient K without using a reference sample. Therefore, even when the intensity of each wavelength of the measurement light L2 varies, it is possible to accurately measure the reflectance of each wavelength of the sample M, thereby improving the accuracy of film thickness measurement.

[0081] The present disclosure is not limited to the above-described embodiment. For example, in (a) of the above Figure 3 and (b) of Figure 3 , a dummy core 13 is provided to suppress crosstalk between the reference light L1 and the measurement light L2, but it is also possible to suppress crosstalk between the reference light L1 and the measurement light L2 by adopting a configuration in which the pixel region 21 is set instead of the optical fiber end 11.

[0082] For example, in the pixel region 21, by disposing a light-shielding filter or the like for pixels 22 located near the boundary (near the center in the column direction) between the first pixel region 21A and the second pixel region 21B, a structure is formed in which the pixels 22 near the boundary do not receive light, achieving the same effect as in the case where the dummy core 13 is provided. Further, for example, in the pixel region 21, by not reading charges from the pixels 22 located near the boundary (near the center in the column direction) between the first pixel region 21A and the second pixel region 21B, the same effect as in the case where the dummy core 13 is provided is achieved.

[0083] Furthermore, for example, when the detection unit 6 is constituted by a CCD light detector V1, the same effect as in the case where the dummy core 13 is provided is achieved by starting the horizontal transfer of the first horizontal shift register 32A and the second horizontal shift register 32B before transferring the charges of the pixels 22 near the boundary between the first pixel region 21A and the second pixel region 21B.

[0084] In addition, in the above-described embodiment, the conversion coefficient K is calculated when measuring the sample M, but the calculation of the conversion coefficient K does not necessarily have to be performed every time the sample M is measured. The calculation of the conversion coefficient K can also be performed only during shipment inspection and maintenance operations. When measuring the sample M, the conversion coefficient K recorded in the calculation unit 7 is uniformly used during shipment inspection and maintenance operations.

[0085] The gist of the present disclosure is as shown in the following [1] to [8]. [1] A film thickness measurement device, comprising: a spectroscopic unit that spectroscopically analyzes each of a reference light output from a light source and a measurement light output from the light source and reflected by a sample; a detection unit that detects a spectroscopic image of the reference light and a spectroscopic image of the measurement light spectroscopically analyzed by the spectroscopic unit; and an analysis unit that analyzes the film thickness of the sample based on reference data obtained from a detection result of the spectroscopic image of the reference light and measurement data obtained from a detection result of the spectroscopic image of the measurement light. The spectroscopic unit wavelength-disperses the reference light and the measurement light in a first direction, and in a second direction intersecting the first direction, images the spectroscopic images of each wavelength. The detection unit has a first pixel region and a second pixel region divided in the second direction, receives the spectroscopic image of the reference light through the first pixel region, and receives the spectroscopic image of the measurement light through the second pixel region. [2] The film thickness measurement device according to [1], wherein the detection unit is a CCD photodetector, and the CCD photodetector has: a first horizontal shift register that transfers charges generated by each column of the first pixel region; and a second horizontal shift register that transfers charges generated by each column of the second pixel region. [3] The film thickness measurement device according to [1], wherein the detection unit is a CCD photodetector, and the CCD photodetector has: a first storage unit that stores charges generated by each column of the first pixel region; a second storage unit that stores charges generated by each column of the second pixel region; a first readout unit that outputs an electrical signal corresponding to the magnitude of the charges stored in the first storage unit for each column; and a second readout unit that outputs an electrical signal corresponding to the magnitude of the charges stored in the second storage unit for each column. [4] The film thickness measurement device according to [1], wherein the detection unit is a CMOS photodetector, and the CMOS photodetector has: a first readout unit that outputs charges generated by each column of the first pixel region; and a second readout unit that outputs charges generated by each column of the second pixel region. [5] The film thickness measuring device according to any one of [1] to [4], comprising: a first optical fiber that guides the reference light to the spectroscopic unit; a second optical fiber that guides the measurement light to the spectroscopic unit; and an optical fiber end that bundles the cores of the first optical fiber and the second optical fiber, wherein the arrangement directions of the cores of the first optical fiber and the second optical fiber of the optical fiber end are the same as the extending direction of the slit of the input surface of the spectroscopic unit. [6] The film thickness measuring device according to [5], wherein in the optical fiber end, a dummy core is provided that physically separates the core of the first optical fiber and the core of the second optical fiber. [7] The film thickness measuring device according to any one of [1] to [6], comprising a calculation unit that calculates a conversion coefficient for converting the detected value of the intensity of each wavelength of the reference light into a value equivalent to the intensity of each wavelength of the measurement light from a reference sample, wherein the calculation unit calculates the conversion coefficient using the exposure time ratio between the first pixel region and the second pixel region, and the analysis unit calculates the reflectance of each wavelength of the sample based on the detected value of the intensity of each wavelength of the reference light and the value equivalent to the intensity of each wavelength of the measurement light from the reference sample obtained by the conversion coefficient. [8] A film thickness measuring method, comprising: a spectroscopic step of spectroscopically analyzing each of the reference light output from a light source and the measurement light output from the light source and reflected by a sample; a detection step of detecting the spectroscopic image of the reference light and the spectroscopic image of the measurement light spectroscopically analyzed in the spectroscopic step; and an analysis step of analyzing the film thickness of the sample based on reference data obtained from the detection result of the spectroscopic image of the reference light and measurement data obtained from the detection result of the spectroscopic image of the measurement light, wherein in the spectroscopic step, the reference light and the measurement light are wavelength-dispersed in a first direction, and in a second direction intersecting the first direction, the spectroscopic image of each wavelength is imaged, and in the detection step, a first pixel region and a second pixel region divided in the second direction are used, and the spectroscopic image of the reference light is received through the first pixel region, and the spectroscopic image of the measurement light is received through the second pixel region. Symbol Description

[0086] 1... Film thickness measuring device; 2... Light source; 5... Spectral splitting unit; 5a... Input surface; 6... Detection unit; 7... Calculation unit; 8... Analysis unit; 9A... First optical fiber; 9B... Second optical fiber; 11... Optical fiber end; 12A, 12B... Fiber cores; 13...Dummy fiber core; 14... Slit; 21A... First pixel region; 21B... Second pixel region; 32A... First horizontal shift register; 32B... Second horizontal shift register; 41A... First storage unit; 41B... Second storage unit; 42A... First readout unit; 42B... Second readout unit; 57A... First readout unit; 57B... Second readout unit; L1... Reference light; L2... Measurement light; D1... First direction; D2... Second direction; M... Specimen; P1, P2... Spectral images; V1, V2... CCD photodetectors; V3... CMOS photodetector.

Claims

1. A film thickness measuring device, wherein, it comprises: a spectroscopic unit that spectroscopically analyzes each of a reference light output from a light source and a measurement light output from the light source and reflected by a sample; a detection unit that detects a spectroscopic image of the reference light and a spectroscopic image of the measurement light spectroscopically analyzed by the spectroscopic unit; and an analysis unit that analyzes the film thickness of the sample based on reference data obtained from a detection result of the spectroscopic image of the reference light and measurement data obtained from a detection result of the spectroscopic image of the measurement light, the spectroscopic unit wavelength-disperses the reference light and the measurement light in a first direction and forms an image of the spectroscopic image of each wavelength in a second direction intersecting the first direction, the detection unit has a first pixel region and a second pixel region divided in the second direction, receives the spectroscopic image of the reference light through the first pixel region, and receives the spectroscopic image of the measurement light through the second pixel region.

2. The film thickness measuring device according to claim 1, wherein, the detection unit is a CCD photodetector, and the CCD photodetector has: a first horizontal shift register that transfers charges generated by each column of the first pixel region; and a second horizontal shift register that transfers charges generated by each column of the second pixel region.

3. The film thickness measuring device according to claim 1, wherein, the detection unit is a CCD photodetector, and the CCD photodetector has: a first storage unit that stores charges generated by each column of the first pixel region; a second storage unit that stores charges generated by each column of the second pixel region; a first readout unit that outputs an electrical signal for each column corresponding to the magnitude of the charges stored in the first storage unit; and a second readout unit that outputs an electrical signal for each column corresponding to the magnitude of the charges stored in the second storage unit.

4. The film thickness measuring device according to claim 1, wherein, the detection unit is a CMOS photodetector, and the CMOS photodetector has: a first readout unit that outputs charges generated by each column of the first pixel region; and a second readout unit that outputs charges generated by each column of the second pixel region.

5. The film thickness measuring device according to any one of claims 1 to 4, wherein, it comprises: a first optical fiber that guides the reference light to the spectroscopic unit; a second optical fiber that guides the measurement light to the spectroscopic unit; and an optical fiber end that bundles the core of the first optical fiber and the core of the second optical fiber, the arrangement direction of the core of the first optical fiber and the core of the second optical fiber at the optical fiber end is the same as the extending direction of the slit of the input surface of the spectroscopic unit.

6. The film thickness measuring device according to claim 5, wherein, at the optical fiber end, a dummy core that physically separates the core of the first optical fiber and the core of the second optical fiber is provided.

7. The film thickness measuring device according to any one of claims 1 to 4, wherein, it comprises: a calculation unit that calculates a conversion coefficient for converting a detection value of the intensity of each wavelength of the reference light into a value equivalent to the intensity of each wavelength of the measurement light from a reference sample, The calculation unit calculates the conversion coefficient using the exposure time ratio between the first pixel region and the second pixel region. The analysis unit calculates the reflectance of each wavelength of the sample based on the detected value of the intensity of each wavelength of the reference light and the value of the intensity of each wavelength of the measurement light equivalent to that from the reference sample obtained from the conversion coefficient.

8. A film thickness measurement method, comprising: a spectroscopic step of spectroscopically separating each of the reference light output from a light source and the measurement light output from the light source and reflected by a sample; a detection step of detecting the spectroscopic image of the reference light and the spectroscopic image of the measurement light spectroscopically separated in the spectroscopic step; and an analysis step of analyzing the film thickness of the sample based on reference data obtained from the detection result of the spectroscopic image of the reference light and measurement data obtained from the detection result of the spectroscopic image of the measurement light, wherein, in the spectroscopic step, the reference light and the measurement light are wavelength-dispersed in a first direction, and the spectroscopic image of each wavelength is imaged in a second direction intersecting the first direction; in the detection step, a first pixel region and a second pixel region divided in the second direction are used, the spectroscopic image of the reference light is received by the first pixel region, and the spectroscopic image of the measurement light is received by the second pixel region. ​

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