Optical measurement system

Abstract

An optical measurement system is provided for measuring film thickness, which is the thickness of a layer contained in a sample. [Solution] The optical measurement system includes a light source that generates measurement light, a light receiving unit that receives reflected light or transmitted light generated when the measurement light is irradiated onto a sample as observation light, a probe that is optically connected to the light source and the light receiving unit and can be positioned at any position, a film thickness calculation unit that calculates the film thickness of the sample from the spectral reflectance or spectral transmittance calculated based on the detection result by the light receiving unit, and a reliability calculation unit that calculates the measurement reliability that indicates how accurately the film thickness calculated by the film thickness calculation unit was measured.

Description

Technical Field

[0001] The present invention relates to a portable optical measurement system, an optical measurement method in the optical measurement system, and a measurement program for realizing the optical measurement method.

Background Art

[0002] There is a demand to manage the film thickness of manufactured products. For such a demand, measurement devices and measurement methods for measuring film thickness are known.

[0003] As an example, measurement devices using electromagnetic induction or eddy current are known. For example, Japanese Patent Laid-Open No. 07-332916 (Patent Document 1) discloses a film thickness gauge that accurately measures the film thickness of a magnetic coating using a current of a practical frequency. Further, Japanese Patent Laid-Open No. 06-317401 (Patent Document 2) discloses a hand-held combined coating thickness gauge capable of measuring the thicknesses of both non-ferrous coatings on an iron substrate and non-conductive coatings on a conductive non-ferrous substrate.

[0004] Also, measurement devices using ultrasonic waves are known. For example, Japanese Patent Laid-Open No. 07-167639 (Patent Document 3) discloses a thickness gauge including a transducer that emits ultrasonic waves into a coating and receives the ultrasonic waves, and generates a conversion signal proportional to the ultrasonic wave signal.

[0005] Furthermore, measurement devices using light are known. For example, International Publication No. 2010 / 013429 (Patent Document 4) discloses a film thickness measurement device that obtains the film thickness of a film formed on a substrate surface by measuring the spectral reflectance.

[0006] Among these measurement devices and measurement methods for measuring film thickness, the measurement accuracy of devices using electromagnetic induction or eddy current, and devices using ultrasonic waves is inferior to that of devices using light. Therefore, it is preferable to use a measurement device using light for measuring film thickness.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Laid-Open No. 07-332916 [Patent Document 2] Japanese Patent Laid-Open No. 06-317401 [Patent Document 3] Japanese Patent Laid-Open No. 07-167639 [Patent Document 4] International Publication No. 2010 / 013429 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] The film thickness measuring device disclosed in the above Patent Document 4 is configured such that light from a light source is incident perpendicularly on a measurement target surface provided with a film, and the light reflected from the measurement target surface is incident on a spectroscopic sensor. In order to make the light from the light source incident perpendicularly on the measurement target surface, a stationary configuration is assumed.

[0009] For product quality control and the like, for example, there is a demand for easy measurement at an arbitrary position on a production line. There is also a demand for easily measuring samples with a curved surface or a complex shape. However, the above prior art does not provide a solution means that satisfies such demands.

[0010] One object of the present invention is to provide an optical measurement system and the like that can appropriately measure the film thickness of a sample. [Means for Solving the Problems]

[0011] According to an aspect of the present invention, there is provided an optical measurement system for measuring the film thickness, which is the thickness of a layer included in a sample. The optical measurement system includes a light source that generates measurement light, a light receiving unit that receives, as observation light, reflected light or transmitted light generated by irradiating the sample with the measurement light, a probe that is optically connected to the light source and the light receiving unit and can be disposed at an arbitrary position, a film thickness calculation unit that calculates the film thickness of the sample from the spectral reflectance or spectral transmittance calculated based on the detection result by the light receiving unit, and a reliability calculation unit that calculates a measurement reliability indicating how appropriately the film thickness calculated by the film thickness calculation unit is measured.

[0012] The optical measurement system may further include an output unit that notifies the measurement reliability calculated by the reliability calculation unit.

[0013] The output unit may generate a notification sound corresponding to the level of the measurement reliability.

[0014] The output unit may output at least one of light and an image indicating the measurement reliability.

[0015] The optical measurement system may further include a determination unit that determines, as a measurement result, the film thickness at the time when the measurement reliability satisfies a predetermined condition.

[0016] The film thickness calculation unit may calculate the film thickness of the sample based on a peak appearing in a spectrum calculated by frequency-converting the spectral reflectance or spectral transmittance. The reliability calculation unit may calculate the measurement reliability based on the magnitude of the peak appearing in the spectrum.

[0017] The film thickness calculation unit may calculate the film thickness of the sample by fitting the parameters of a model indicating the spectral reflectance or spectral transmittance to match the spectral reflectance or spectral transmittance calculated based on the observation light. The reliability calculation unit may calculate the measurement reliability based on the fitting result determined by the film thickness calculation unit.

[0018] The probe may be configured to be changeable to different types according to the sample.

[0019] At least the film thickness calculation unit and the reliability calculation unit may be mounted in a housing independent of the probe.

[0020] At least the probe, the light source, and the light receiving unit may be mounted in a single housing.

[0021] According to another aspect of the present invention, an optical measurement method for measuring the film thickness, which is the thickness of a layer included in a sample, is provided. The optical measurement method includes: irradiating the sample with measurement light generated by a light source through a probe that can be arranged at an arbitrary position; receiving, as observation light, reflected light or transmitted light generated by irradiating the sample with the measurement light by a light receiving unit, and calculating the film thickness of the sample from the spectral reflectance or spectral transmittance calculated based on the detection result by the light receiving unit; and calculating a measurement reliability indicating how appropriately the calculated film thickness is measured.

[0022] According to still another aspect of the present invention, a measurement program for measuring the film thickness, which is the thickness of a layer included in a sample, is provided. The measurement program causes a computer to execute: calculating the film thickness of the sample from the spectral reflectance or spectral transmittance calculated based on a detection result obtained by receiving reflected light or transmitted light generated when irradiating the sample with measurement light generated by a light source through a probe that can be arranged at an arbitrary position; and calculating a measurement reliability indicating how appropriately the calculated film thickness is measured.

Effects of the Invention

[0023] According to an embodiment of the present invention, the film thickness of a sample can be appropriately measured.

Brief Description of the Drawings

[0024]

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Embodiments for Carrying Out the Invention

[0025] Embodiments of the present invention will be described in detail with reference to the drawings. For the same or corresponding parts in the drawings, the same reference numerals are given and the description thereof will not be repeated.

[0026] <A. Optical Measurement System> First, a configuration example of the optical measurement system 1 according to the present embodiment will be described. The optical measurement system 1 is an optical film thickness measurement device that measures the film thickness of a sample using light. More specifically, the optical measurement system 1 is a spectroscopic interference type film thickness measurement device.

[0027] In this specification, "film thickness" means the thickness of a specific layer or film included in an arbitrary sample. That is, the optical measurement system 1 measures the film thickness, which is the thickness of the layer included in the sample.

[0028] In the following description, an optical system (reflected light observation system) that irradiates a sample with light and observes the reflected light thereof will be mainly described. However, it is naturally applicable to an optical system (transmitted light observation system) that irradiates a sample with light and observes the transmitted light thereof. Therefore, in the following description, unless otherwise specified, the term "reflected light" includes "transmitted light" in addition to the original "reflected light". Similarly, the term "reflectance" includes "transmittance" in addition to the original "reflectance".

[0029] (a1: System configuration example) FIG. 1 is a schematic diagram showing a configuration example of an optical measurement system 1 according to the present embodiment. The optical measurement system 1 includes a measurement device 100 and a probe 200 optically connected to the measurement device 100.

[0030] In particular, the optical measurement system 1 according to the present embodiment is configured as a portable type that can be measured at an arbitrary position. In the configuration example shown in FIG. 1, the user can hold the measurement device 100 with one hand and the probe 200 with the other hand to measure an arbitrary sample at an arbitrary position. Note that it is not necessary for the user to always hold the measurement device 100 and / or the probe 200 during the measurement. In this way, the probe 200 can be arranged at an arbitrary position.

[0031] The measurement device 100 and the probe 200 are connected via an optical fiber 10 and an optical fiber 20. One end of the optical fiber 10 and one end of the optical fiber 20 are detachably connected via a coupler 28.

[0032] A plurality of types of probes 200 may be prepared according to the shape and characteristics of the sample. In this case, a coupler 28 may be provided so that the probe 200 can be easily replaced. The coupler 28 preferably adopts a configuration that allows the probe 200 to be attached and detached with one touch, for example. The coupler 28 preferably has a structure that has no influence on the measurement by connection, detachment, replacement, etc. However, when only one type of probe 200 is used, the coupler 28 may be omitted.

[0033] The optical fiber 10 is a Y-shaped optical fiber, and branching fibers 12 and 14 extend from a branching portion 16 of the optical fiber 10.

[0034] (a2: Configuration example of the measuring device 100) FIG. 2 is a schematic diagram showing a functional configuration example of the optical measurement system 1 according to the present embodiment. Referring to FIG. 2, the measuring device 100 irradiates a sample with light and receives light (reflected light or transmitted light) generated by irradiating the sample with light. In the following description, the light irradiated on the sample is referred to as "measurement light" (measurement light 22 shown in FIG. 2), and the light generated by irradiating the sample with light is also referred to as "observation light" (observation light 24 shown in FIG. 2).

[0035] More specifically, the measuring device 100 includes, as typical components, a light source 102, a spectroscopic measurement unit 104, an output unit 106, an operation unit 108, an arithmetic processing unit 110, and a power supply unit 130. The components included in the measuring device 100 are packaged and housed in a housing. In the configuration example shown in FIG. 2, the arithmetic processing unit 110 is mounted in a housing independent of the probe 200.

[0036] The probe 200 is optically connected to the light source 102 and the spectroscopic measurement unit 104. More specifically, the branching fiber 12 is optically connected to the light source 102, and the branching fiber 14 is optically connected to the spectroscopic measurement unit 104. The branching fiber 12 irradiates (projects) the measurement light 22 from the light source 102 onto the sample and guides the observation light 24 from the sample to the spectroscopic measurement unit 104.

[0037] The light source 102 has a light emitter such as a white LED or a natural light LED, for example, and generates the measurement light 22. The measurement light 22 generated by the light source 102 is preferably broad light having components over a predetermined wavelength range. In order to miniaturize the measuring device 100, the light source 102 preferably operates even at a relatively low voltage.

[0038] The spectroscopic measurement unit 104 corresponds to a light receiving unit that receives, as the observation light 24, the reflected light or transmitted light generated by irradiating the sample with the measurement light 22. The spectroscopic measurement unit 104 outputs the intensity for each wavelength of the observation light 24. Typically, the spectroscopic measurement unit 104 includes a diffraction grating that diffracts the observation light 24 incident via the branching fiber 14, and a light receiving element having a plurality of channels arranged in association with the diffraction grating. The light receiving element is composed of a line sensor or a two-dimensional sensor, etc., and can output the intensity for each wavelength component as a detection result.

[0039] As the optical system of the spectroscopic measurement unit 104, for example, a Czerny-Turner type, a Fastie-Ebert type, a Paschen-Runge type, etc. can be adopted.

[0040] The output unit 106 outputs the calculation result by the arithmetic processing unit 110 to the user. In particular, the output unit 106 notifies the measurement reliability calculated by the arithmetic processing unit 110. As the output unit 106, a display, a touch panel, an LED that notifies the user of information by an image or light may be adopted, or a sound generation unit (speaker) that notifies the user of information by sound may be adopted, or a vibrator that notifies the user of information by vibration may be adopted.

[0041] The operation unit 108 receives a user operation. The operation unit 108 may adopt any input device such as a touch panel, a keyboard, a mouse, a tablet, a button, etc.

[0042] The arithmetic processing unit 110 calculates the film thickness of the sample from the spectroscopic reflectance (or spectroscopic transmittance) calculated based on the detection result (intensity for each wavelength of the observation light 24) by the spectroscopic measurement unit 104 as a film thickness calculation function. In addition to the film thickness calculation function, the arithmetic processing unit 110 has a reliability calculation function. That is, the arithmetic processing unit 110 calculates the measurement reliability indicating how appropriately the calculated film thickness is measured. Further, the arithmetic processing unit 110 also executes various processes as described later.

[0043] As an algorithm for determining the film thickness of a sample, the FFT (Fast Fourier Transform) method, the optimization method, or the like can be adopted.

[0044] The power supply unit 130 supplies power to each component of the measuring device 100 including the arithmetic processing unit 110. The power supply unit 130 adjusts the voltage of the power supplied from an external power source and provides it to each component of the measuring device 100. The power supply unit 130 may incorporate a battery 132 so that the power supply to each component of the measuring device 100 can be continued even when the power supply from the external power source is interrupted.

[0045] FIG. 3 is a schematic diagram showing a functional configuration example of the arithmetic processing unit 110 included in the measuring device 100 according to the present embodiment. Referring to FIG. 3, the arithmetic processing unit 110 includes a processor 112, a main memory 114, an internal interface 116, a general-purpose interface 117, a network interface 118, and a storage 120.

[0046] The processor 112 is typically an arithmetic processing unit such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and reads and executes one or more programs stored in the storage 120 into the main memory 114. The main memory 114 is a volatile memory such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory), and functions as a working memory for the processor 112 to execute programs.

[0047] The storage 120 is composed of a non-volatile memory such as a hard disk or a flash memory, and stores various programs and data. More specifically, the storage 120 stores an operating system 122 (OS: Operating System), a measurement program 124, a detection result 126, and a measurement result 128.

[0048] The operating system 122 provides an environment in which the processor 112 executes programs. The measurement program 124 is executed by the processor 112 to implement an optical measurement method or the like according to the present embodiment. The detection result 126 includes data on the intensity for each wavelength of the observation light 24 output by the spectroscopic measurement unit 104. The measurement result 128 includes the measurement result of the film thickness of the sample obtained by executing the measurement program 124.

[0049] The internal interface 116 mediates data transmission between components included in the measuring device 100.

[0050] The general-purpose interface 117 is configured by, for example, USB (Universal Serial Bus) or the like, and mediates data transmission with an external device. The network interface 118 is configured by, for example, a wired LAN or a wireless LAN or the like, and mediates data transmission with an external device. The general-purpose interface 117 and / or the network interface 118 may transmit the detection result 126 stored in the storage 120 to another information processing device and receive the measurement result 128 processed by another information processing device. By providing an interface with such another information processing device, another information processing device can be responsible for all or part of the necessary analysis processing.

[0051] The measurement program 124 and the like stored in the storage 120 may be installed via an arbitrary recording medium (for example, an optical disk or the like), or may be downloaded from a server device via the network interface 118 or the like.

[0052] The measurement program 124 may be one that calls necessary program modules among the program modules provided as part of the operating system 122 in a predetermined array at a predetermined timing to execute processing. In such a case, the measurement program 124 that does not include such a module is also included in the technical scope of the present invention. The measurement program 124 may be provided by being incorporated into a part of another program.

[0053] Note that all or part of the functions provided by the processor 112 of the arithmetic processing unit 110 executing a program may be realized by a hardwired logic circuit (for example, an FPGA (field-programmable gate array), an ASIC (application specific integrated circuit), etc.). Also, in addition to a processor such as a CPU or a GPU, it may be realized using a SoC (System on Chip) that integrates a DSP (Digital Signal Processor) and an ISP (Image Signal Processor), etc.

[0054] (a3: Configuration example of the probe 200) FIG. 4 is a schematic diagram showing an example of the appearance of the probe 200 used in the optical measurement system 1 according to the present embodiment. The probe 200 shown in FIG. 4 has a light transmitting and receiving unit 202 that irradiates the measurement light 22 supplied from the measurement device 100 and receives the observation light 24 generated in the sample. The end face of the probe 200 is flat and circular, and the light transmitting and receiving unit 202 is formed in a depression formed in the central portion of the circle.

[0055] FIG. 5 is a schematic diagram showing an example of the cross-sectional structure of the probe 200 used in the optical measurement system 1 according to the present embodiment.

[0056] As shown in Fig. 5(A), an optical path 204 optically connected to the optical fiber 20 is formed inside the probe 200. The optical path 204 guides the light supplied through the optical fiber 20 to the light transmitting and receiving part 202, and guides the light incident on the light transmitting and receiving part 202 to the optical fiber 20.

[0057] In the measurement state, with the end face of the probe 200 shown in Fig. 5(A) in contact with the sample 4, the sample 4 is irradiated with the measurement light 22. The observation light 24 generated in the sample 4 is analyzed and processed by the measuring device 100, and the film thickness of the sample 4 is measured.

[0058] As shown in Fig. 5(B), a reference cap 30 to be attached to the probe 200 may be prepared. The reference cap 30 is used for calibration of the optical measurement system 1. Further, the reference cap 30 can also be used to prevent the intrusion of dust, etc. when the probe 200 is stored.

[0059] The reference cap 30 has a mirror 32 provided at a position facing the light transmitting and receiving part 202 of the probe 200 in a state of being attached to the probe 200. The mirror 32 reflects the measurement light 22 irradiated from the light transmitting and receiving part 202 and returns it to the light transmitting and receiving part 202 as the observation light 24. The observation light 24 measured with the reference cap 30 attached to the probe 200 is used as a reference (reference) for the reflectance. That is, the observation light 24 measured with the reference cap 30 attached to the probe 200 is acquired as a reference signal.

[0060] As described above, a plurality of types of probes 200 may be prepared according to the shape and characteristics of the sample 4. The user optically connects an appropriate probe 200 among the plurality of types of probes 200 to the measuring device 100 via the coupler 28 according to the sample 4. In this way, the probe 200 is configured to be changeable to different types according to the sample 4.

[0061] As an example of a plurality of types of probes 200, there are (1) a stethoscope-type probe, (2) a pen-type probe, (3) a V-groove type probe, (4) an L-shaped probe, (5) a mini-spot probe, (6) a non-contact probe, (7) a tip-movable probe, (8) a probe for a curved surface, (9) a probe in liquid, (10) a probe for an oil film, (11) a multi-angle probe, and the like.

[0062] (1) The stethoscope-type probe has a shape as shown in FIG. 4 described above and is suitable for measuring the film thickness of the sample 4 that can be pressed against the measurement surface. For example, it can be used to measure the film thickness of a transparent or translucent planar sample (e.g., a wrap for food packaging, a PET film, a glass substrate, a planar substrate such as a semiconductor, a coating layer formed on a planar substrate, etc.). Since the stethoscope-type probe has a flat end face, by pressing it against the sample 4, it is possible to easily achieve perpendicular emission of the light irradiation angle with respect to the measurement surface (optical axis adjustment to make the incident angle and the reflection angle 0°). That is, the measurement light 22 can be irradiated perpendicularly to the measurement surface without the user being aware of it.

[0063] (2) The pen-type probe is mainly used to measure the local film thickness of the sample 4.

[0064] FIG. 6 is a schematic diagram showing an example of a pen-type probe 200C used in the optical measurement system according to the present embodiment. Referring to FIG. 6, the probe 200C measures the film thickness of the sample 4 having a local three-dimensional structure included therein. By making it have a shape similar to a pen, the gripability and workability of the user can be improved.

[0065] An attachment corresponding to the sample 4 may be attached to the tip of the probe 200C.

[0066] FIG. 7 is a schematic diagram showing an example of an attachment attached to a pen-type probe 200C used in the optical measurement system according to the present embodiment. FIG. 7(A) shows an example of an attachment 210 that widens towards the tip. By attaching the attachment 210, it becomes easier to press the probe 200C when the measurement surface of the sample 4 is flat. FIG. 7(B) shows an example of an attachment 212 that narrows towards the tip. By attaching the attachment 212, it becomes easier to press the probe 200C even when the measurement surface of the sample 4 is narrow. Thus, by preparing an attachment that can be attached to the tip of the probe 200C, it is possible to cope with samples 4 of various shapes.

[0067] (3) The V-groove type probe is mainly used to measure the film thickness of a coating layer formed on the outer side of a cylindrical sample 4 (for example, a catheter or a metal tube).

[0068] FIG. 8 is a schematic diagram showing an example of a V-groove type probe 200D used in the optical measurement system according to the present embodiment. Referring to FIG. 8, the probe 200D includes a pair of support members 214 that support the sample 4. An interval through which the measurement light 22 and the observation light 24 pass is provided between the support members 214.

[0069] By supporting the sample 4 with the support members 214 of the V-groove type probe 200D, it is possible to easily achieve perpendicularity of the light irradiation angle with respect to the measurement region portion (micro surface) on the curved surface of the sample 4. Note that a mechanism may be adopted that allows the opening angle of the support member 214 to be adjusted according to the curvature of the sample 4. Specifically, a mechanism may be adopted in which a spring or the like is disposed between the support members 214 that form the V-shaped groove so that the opening angle can be adjusted according to the magnitude of the force pressing the sample 4.

[0070] (4) The L-shaped probe is mainly used to measure the film thickness of a coating layer formed inside a cylindrical sample. The L-shaped probe is configured in a bent shape so that it can be accessed even when there is only a limited space above the sample.

[0071] FIG. 9 is a schematic diagram showing an example of an L-shaped probe used in the optical measurement system according to the present embodiment. Referring to FIG. 9(A), inside the L-shaped probe 200E, there are provided an optical path 204 optically connected to an optical fiber 20 and a mirror 216. The measurement light 22 irradiated from the optical path 204 has its propagation direction changed by 90° by the mirror 216 and is irradiated onto the measurement surface of the sample 4. Similarly, the observation light 24 from the sample 4 has its propagation direction changed by 90° by the mirror 216 and is guided to the optical path 204.

[0072] FIG. 9(B) shows a probe 200F in which a support member 218 is provided on the outer peripheral side of the probe 200E shown in FIG. 9(A). By selecting the support member 218 of the probe 200F according to the inner diameter of the sample 4, the probe 200F can be easily rotated inside the cylindrical sample 4. As a result, the film thickness of the coating layer formed inside the sample 4 can be measured over the entire circumference.

[0073] (5) The mini-spot probe is mainly used to measure the film thickness of samples such as those with a rough surface, those with uneven surfaces, and those with light-diffusing surfaces in a stethoscope-type probe. Since the irradiation area (light-receiving area) of the measurement light 22 of the mini-spot probe is a minute spot, noise components included in the observation light 24 can be reduced.

[0074] (6) The non-contact probe has an optical system designed to enable measurement even when the distance from the measurement position on the sample to the probe is relatively long, and measurement can be performed without directly contacting the sample.

[0075] FIG. 10 is a schematic diagram showing an example of a non-contact probe 200G used in the optical measurement system according to the present embodiment. Referring to FIG. 10, the probe 200G includes lenses 220 and 222, and converges the measurement light 22 irradiated from the light guide path 204 onto the sample 4. Similarly, the lenses 220 and 222 guide the observation light 24 from the sample 4 to the light guide path 204. By adopting such an optical system, the film thickness of the sample 4 can be measured without directly contacting the probe 200G with the sample 4.

[0076] Since the non-contact probe is held and used by the user, the measurement mode (described later) provided by the optical measurement system 1 is more effective.

[0077] Note that FIG. 10 shows a configuration example in which the focal position is fixed, but the focal position may be variable.

[0078] FIG. 11 is a schematic diagram showing an example of a non-contact probe 200H used in the optical measurement system according to the present embodiment. Referring to FIGS. 11(A) and 11(B), in the probe 200H, the lens 222 is configured to be able to change its position in the optical axis direction. By moving the lens 222 away from the lens 220, the focal position becomes longer (see FIG. 11(A)), and by moving the lens 222 closer to the lens 220, the focal position becomes shorter (see FIG. 11(B)).

[0079] (7) The tip movable probe is used, for example, to measure the film thickness inside a structure with a narrow entrance or the film thickness of a sample with a curved access path.

[0080] FIG. 12 is a schematic diagram showing an example of the tip movable probe 200I used in the optical measurement system according to the present embodiment. Referring to FIG. 12, the tip of the probe 200I is provided with a mirror (not shown) that changes the propagation directions of the measurement light 22 and the observation light 24, similar to the L-shaped probe shown in FIG. 9. Then, as shown in FIGS. 12(A) and 12(B), the tip portion of the probe 200I has a structure in which the tip can be freely bent by the user's operation. This is effective when the user cannot directly press the probe.

[0081] (8) The curved surface probe is mainly used to measure the film thickness of a sample whose measurement position is a curved surface.

[0082] FIG. 13 is a schematic diagram showing an example of the curved surface probe 200J used in the optical measurement system according to the present embodiment. Referring to FIG. 13, a flexible portion 226 that can be bent is provided at the tip of the probe 200J. The flexible portion 226 is made of a soft material. By pressing the probe 200J against an arbitrary measurement position of the sample 4, the user can deform the flexible portion 226 to achieve an appropriate state (that is, a state in which the light irradiation angle with respect to the measurement surface is perpendicular).

[0083] A contact portion 228 that contacts the sample 4 is provided at the tip of the flexible portion 226. A light transmitting and receiving portion 202 is provided at the center of the contact portion 228, and a rubber packing 230 is provided on the outer periphery of the exposed surface of the contact portion 228. By providing the rubber packing 230, the contact property with the sample 4 can be enhanced.

[0084] (9) The liquid immersion probe is mainly used to measure the film thickness of a sample present in a liquid.

[0085] FIG. 14 is a schematic diagram showing an example of a probe 200K for liquid used in the optical measurement system according to the present embodiment. Referring to FIG. 14, the probe 200K adopts, as an example, a form similar to that of a stethoscope-type probe, but each part is sealed so that it can be used even in a liquid.

[0086] (10) The probe for oil film has a portion in contact with the measurement position at the tip of the probe formed in a needle shape, and can easily measure the film thickness of a liquid film including an oil film.

[0087] FIG. 15 is a schematic diagram showing an example of a probe 200L for oil film used in the optical measurement system according to the present embodiment. Referring to FIG. 15, the probe 200L adopts, as an example, a form similar to that of a stethoscope-type probe, but a needle portion 234 is provided so as to reduce the influence on the oil film.

[0088] (11) The multi-angle probe adopts a configuration that can vary the incident angle of the measurement light 22 with respect to the sample 4.

[0089] FIG. 16 is a schematic diagram showing an example of a multi-angle probe 200M used in the optical measurement system according to the present embodiment. Referring to FIG. 16, the probe 200M is configured to be able to incident the measurement light 22 at an angle not perpendicular to the measurement surface of the sample 4. Further, since the observation light 24 from the sample 4 also propagates at an angle not perpendicular to the measurement surface of the sample 4, such observation light 24 is also configured to be received.

[0090] In FIGS. 1 and 2 described above, a configuration example in which the measuring device 100 and the probe 200 are separate bodies is shown, but the measuring device 100 and the probe 200 may be connected, or the measuring device 100 and the probe 200 may be integrated.

[0091] FIG. 17 is a diagram showing an example of the usage form of the measuring device 100 and the probe 200 in the optical measurement system according to the present embodiment.

[0092] FIG. 17(A) shows a configuration example in which the measuring device 100 and the probe 200 are connected and integrated. By configuring the probe 200 to irradiate the measurement light 22 upward, a desktop optical measurement system suitable for measuring the film thickness of a sample 4 such as a film can be realized.

[0093] Referring to FIG. 17(B), a configuration example in which the measuring device 100 and the probe 200 are integrated is shown. By adopting such an integrated configuration, the overall configuration of the optical measurement system can be simplified.

[0094] (a4: Modification Example 1: Integrated Type) FIG. 18 is a schematic diagram showing an optical measurement system 1A according to a modification example of the present embodiment. Referring to FIG. 18, the optical measurement system 1A includes a measurement device 100A in which the functions of the measurement device 100 and the probe 200 shown in FIGS. 1 and 2 are packaged.

[0095] More specifically, the measurement device 100A includes, as typical components, a light source 102, a spectroscopic measurement unit 104, an output unit 106, an operation unit 108, an arithmetic processing unit 110, a power supply unit 130, and a probe 200. The probe 200 is disposed at a portion exposed from the housing of the measurement device 100A so as to be able to contact the sample. Thus, in the configuration example shown in FIG. 18, the probe 200, the light source 102, and the spectroscopic measurement unit 104 are mounted in a single housing.

[0096] Each component shown in FIG. 18 has substantially the same function as the component with the same reference numeral shown in FIG. 2, and thus, detailed description will not be given here. However, the light source 102 is optically connected to the probe 200 via an optical fiber 52 disposed in the housing of the measurement device 100A, and the spectroscopic measurement unit 104 is optically connected to the probe 200 via an optical fiber 54 disposed in the housing of the measurement device 100A.

[0097] (a5: Modification Example 2: Wireless Connection Configuration) Although the configuration examples in FIGS. 1 and 2 above show the measurement device 100 and the probe 200 optically connected, the measurement device 100 and the probe 200 may be wirelessly connected.

[0098] FIG. 19 is a schematic diagram showing an optical measurement system 1B according to another modification of the present embodiment. Referring to FIG. 19, the optical measurement system 1B includes a measurement device 100B and a highly functional probe 200B.

[0099] The measurement device 100B includes, as typical components, an output unit 106, an operation unit 108, an arithmetic processing unit 110, a power supply unit 130, and a communication unit 134. The components included in the measurement device 100B are packaged and housed in a housing.

[0100] In addition to the probe 200, the highly functional probe 200B includes a light source 102, a spectroscopic measurement unit 104, a power supply unit 130, and a communication processing unit 136. The components included in the highly functional probe 200B are packaged and housed in a housing. Thus, in the configuration example shown in FIG. 19, the probe 200, the light source 102, and the spectroscopic measurement unit 104 are mounted in a single housing.

[0101] The communication unit 134 of the measurement device 100B and the communication processing unit 136 of the highly functional probe 200B exchange the detection results (intensities for each wavelength of the observation light 24) by the spectroscopic measurement unit 104 through wireless communication. As the wireless communication, any method such as wireless LAN, Bluetooth (registered trademark), infrared communication, or a public wireless line such as 4G or 5G can be adopted.

[0102] In addition to various processes in the highly functional probe 200B, the communication processing unit 136 wirelessly transmits the detection results by the spectroscopic measurement unit 104. The communication unit 134 outputs the detection results by the spectroscopic measurement unit 104 wirelessly transmitted by the communication processing unit 136 to the arithmetic processing unit 110.

[0103] Since each of the other components shown in FIG. 19 has substantially the same function as the component with the same reference numeral shown in FIG. 2, detailed description thereof will not be given here.

[0104] The operating state of the highly functional probe 200B may be controlled by a command from the measuring device 100B. For example, in response to a command from the measuring device 100B, irradiation of the measurement light 22 from the light source 102 of the highly functional probe 200B may be enabled / disabled, or wireless transmission of the communication processing unit 136 of the highly functional probe 200B may be enabled / disabled.

[0105] When using the highly functional probe 200B, it may be operated by power supply from the battery 132 of the power supply unit 130 instead of power supply from an external power source.

[0106] (a6: Implementation method) The above-described measuring devices 100, 100A, and 100B may be implemented using a small personal computer. In this case, many components included in the measuring devices 100, 100A, and 100B will be included in the personal computer. Alternatively, the above-described measuring devices 100, 100A, and 100B may be implemented using a smartphone, a tablet, or the like.

[0107] The implementation method of the optical measurement system 1 according to the present embodiment may be in any form, and may be appropriately implemented using technologies available in each era.

[0108] <B. Example of film thickness measurement process> Next, an example of the film thickness measurement process by the optical measurement system 1 according to the present embodiment will be described.

[0109] FIG. 20 is a schematic diagram showing an example of the cross-sectional structure of the sample 4 to be measured for film thickness by the optical measurement system 1 according to the present embodiment. For convenience of explanation, FIG. 20 shows a sample 4 in which a coating layer 41 is formed on a substrate layer 42. It is assumed that the coating layer 41 is in contact with the air layer 40.

[0110] Referring to FIG. 20, consider the reflected light generated by the reflection of the measurement light 22 irradiated from the probe 200 at the interface between the coating layer 41 and the substrate layer 42. In the following description, each layer is represented using the subscript i. That is, the air layer 40 is given the subscript "0", the coating layer 41 of the sample is given the subscript "1", and the substrate layer 42 is given the subscript "2". Also, the refractive index in each layer is represented using the subscript i as the refractive index n i and is expressed as.

[0111] At the interface between layers with different refractive indices n i reflection of light occurs. Therefore, the amplitude reflectivities (Fresnel coefficients) r (P) i,i+1 , r (S) i,i+1 of the P-polarized component and the S-polarized component at each interface between the i-th layer and the (i + 1)-th layer with different refractive indices can be expressed as follows.

[0112]

Equation

[0113] Here, φ i is the incident angle in the i-th layer. This incident angle φ i can be calculated from the incident angle of the measurement light 22 in the uppermost air layer 40 according to Snell's law as follows.

[0114] N0sinφ0 = N i sinφ i In a layer having a film thickness that allows light to interfere, the light reflected with the amplitude reflectivity represented by the above equation travels back and forth in the layer many times. Therefore, since the optical path lengths are different between the light directly reflected at the interface with the adjacent layer and the light after multiple reflections in the layer, the phases are different from each other, and light interference occurs on the surface of the coating layer 41. In order to show such an interference effect of light in each layer, the phase angle β i of the light in the i-th layer is introduced and can be expressed as follows.

[0115]

Number

[0116] Here, d i represents the film thickness of the i-th layer, and λ represents the wavelength of the incident light.

[0117] To simplify further, when the sample 4 is irradiated with light perpendicular to it, that is, when the incident angle φ i = 0, the distinction between P-polarized light and S-polarized light disappears, and the amplitude reflectance and the phase angle β1 of the film thickness at the interface between each layer are as follows.

[0118]

Number

[0119] Furthermore, the reflectance R of the sample 4 shown in FIG. 20 is as follows.

[0120]

Number

[0121] In the above equation, considering the frequency conversion (Fourier transform) of the phase angle β1, the phase factor cos2β1 becomes non-linear with respect to the reflectance R. Therefore, a conversion to a function having linearity with respect to this phase factor cos2β1 is performed. As an example, the reflectance R is converted as shown in the following equation, and the wavenumber conversion reflectance R’ which is an independent variable is defined.

[0122]

Number

[0123] This wavenumber conversion reflectance R’ becomes a linear equation with respect to the phase factor cos2β1 and has linearity. Here, R a is the intercept in the wavenumber conversion reflectance R’, and R bis the slope in the wavenumber-converted reflectance R'. That is, this wavenumber-converted reflectance R' is a function for linearizing the value of the reflectance R at each wavelength with respect to the phase factor cos2β1 related to frequency conversion. Note that, as a function for linearizing such a phase factor, a function of 1 / (1 - R) may be used.

[0124] Therefore, the wavenumber K1 in the target coating layer 41 can be defined as follows.

[0125]

Equation

[0126] Here, the propagation characteristics of electromagnetic waves in the coating layer 41 depend on the wavenumber K1. That is, it can be understood that light having a wavelength λ in a vacuum has a longer wavelength from λ to λ / n1 in the layer because its light speed decreases in the layer. Considering such a wavelength dispersion phenomenon, the wavenumber-converted reflectance R' is defined as follows.

[0127]

Equation

[0128] From this relationship, when the wavenumber-converted reflectance R' is frequency-converted (Fourier-transformed) with respect to the wavenumber K, a peak appears in the periodic component corresponding to the film thickness d1 of the coating layer 41. By specifying this peak position, the film thickness d1 of the coating layer 41 can be calculated.

[0129] That is, the correspondence between the spectral reflectance measured from sample 4 and the reflectance at each wavelength is converted into the correspondence (wavenumber distribution characteristic) between the wavenumber calculated from each wavelength and the wavenumber-converted reflectance R' calculated according to the above relational expression. A spectrum is calculated by performing a frequency conversion on the function of the wavenumber-converted reflectance R' including this wavenumber K with respect to the wavenumber K, and based on the peak appearing in this calculated spectrum, the film thickness d1 of the coating layer 41 constituting sample 4 is calculated. This means obtaining the amplitude values of each wavenumber component included in the wavenumber distribution characteristic and calculating the film thickness d1 of the coating layer 41 based on the wavenumber components with large amplitude values among them.

[0130] As a method for analyzing the wavenumber components with large amplitude values from the wavenumber distribution characteristic, a method using a discrete Fourier transform such as FFT or a method using an optimization method such as the Maximum Entropy Method can be adopted.

[0131] <C. Measurement reliability> Next, the measurement reliability provided by the optical measurement system 1 according to the present embodiment will be described.

[0132] The optical measurement system 1 according to the present embodiment is configured as a portable type that can be held by a user and measured at an arbitrary position. Further, in the spectroscopic interference method using the reflected light observation system employed by the optical measurement system 1, it is necessary for the measurement light 22 irradiated from the probe 200 to receive the observation light 24 that can be generated by the sample 4 with the probe 200. Therefore, depending on the state in which the user holds it, the measurement may become unstable. Hereinafter, some factors that make the film thickness measurement unstable will be described.

[0133] FIG. 21 is a diagram for explaining the factors that make the film thickness measurement in the optical measurement system 1 according to the present embodiment unstable. FIG. 21 shows an example in which the incident angle of the measurement light 22 with respect to the measurement surface of the sample 4 becomes inappropriate.

[0134] Referring to FIG. 21, when the probe 200 is directly facing the measurement surface of the sample 4, the observation light 24 generated by the measurement light 22 irradiated from the probe 200 will enter the probe 200.

[0135] However, when the probe 200 is tilted with respect to the measurement surface of the sample 4, the observation light 24 generated by the measurement light 22 irradiated from the probe 200 cannot properly enter the probe 200.

[0136] In particular, when using a non-contact probe or a probe for a curved surface, the user has to hold the probe 200 during measurement, so it is difficult to properly maintain the incident angle of the measurement light 22 with respect to the measurement surface of the sample 4, and the measurement may become unstable.

[0137] Similarly, when the surface of the sample 4 is a curved surface or has a complex shape, it is also difficult to properly maintain the incident angle of the measurement light 22 with respect to the measurement surface of the sample 4, so the measurement may become unstable.

[0138] FIG. 22 is a diagram for explaining another factor that makes the film thickness measurement in the optical measurement system 1 according to the present embodiment unstable. FIG. 22 shows an example in which the focus of the measurement light 22 with respect to the measurement surface of the sample 4 becomes inappropriate.

[0139] Referring to FIG. 22, when the distance between the probe 200 and the measurement surface of the sample 4 is appropriate, the measurement light 22 irradiated from the probe 200 is focused on the measurement surface of the sample 4, so appropriate observation light 24 is generated from the sample 4 and enters the probe 200.

[0140] However, when the distance between the probe 200 and the measurement surface of the sample 4 is too far or too close, the measurement light 22 irradiated from the probe 200 is focused at a position away from the measurement surface of the sample 4, so appropriate observation light 24 is not generated.

[0141] In particular, when using a non-contact probe or a probe for a curved surface, the user must hold the probe 200 during measurement, making it difficult to appropriately maintain the distance between the probe 200 and the measurement surface of the sample 4, so the measurement may become unstable.

[0142] Similarly, when the surface of the sample 4 is curved or has a complex shape, it is also difficult to appropriately maintain the distance between the probe 200 and the measurement surface of the sample 4, so the measurement may become unstable.

[0143] FIG. 23 is a diagram for explaining yet another factor that makes the film thickness measurement in the optical measurement system 1 according to the present embodiment unstable. FIG. 23 shows an example caused by the fine structure of the sample 4.

[0144] Referring to FIG. 23, assuming a sample 4 in which a coating layer 41 is formed on a substrate layer 42, there may be fine irregularities in the coating layer 41. Alternatively, there may be fine irregularities on the surface of the coating layer 41. Further, a sample 4 having a structure in which only some regions are measurable is also assumed.

[0145] Since it is necessary to receive the observation light 24 that can occur in the sample 4 with the probe 200, in such a sample 4, depending on the measurement position, the film thickness may not be appropriately measured.

[0146] Referring to FIG. 23, when the measurement surface of the sample 4 is substantially parallel to the end face of the probe 200, the observation light 24 generated by the measurement light 22 irradiated from the probe 200 will enter the probe 200.

[0147] However, when the measurement surface of the sample 4 is largely inclined from the end face of the probe 200, the observation light 24 generated by the measurement light 22 irradiated from the probe 200 cannot appropriately enter the probe 200.

[0148] Therefore, in order to prevent the film thickness measured in the unstable state as described above from being output, the optical measurement system 1 calculates the measurement reliability related to the film thickness measurement.

[0149] In this specification, "measurement reliability" means the degree indicating how appropriately the measurement result (for example, film thickness) measured or calculated is measured.

[0150] As a method for calculating the measurement reliability, any method can be adopted. As a typical example, several calculation methods will be described.

[0151] (c1: Method for calculating measurement reliability by FFT method) First, a method suitable for calculating the film thickness by the FFT method will be described.

[0152] FIG. 24 is a diagram for explaining an example of a method for calculating the measurement reliability in the optical measurement system 1 according to the present embodiment. FIG. 24 shows a method for calculating the measurement reliability in the case of calculating the film thickness of a sample by the FFT method.

[0153] Referring to FIG. 24, the spectral reflectance is calculated from the observation light 24 measured from the sample 4, and after converting it into the wavenumber-converted reflectance R' as described above, frequency conversion (Fourier transform) is performed on the wavenumber K, so that a spectrum with the film thickness on the horizontal axis and the power on the vertical axis (hereinafter, also referred to as "power spectrum") can be calculated.

[0154] In this way, in the FFT method, the film thickness of the sample 4 is calculated based on the peak appearing in the spectrum calculated by frequency-converting the spectral reflectance or spectral transmittance.

[0155] Regarding the calculated power spectrum, the measurement reliability can be calculated based on the peak appearing at the position corresponding to the film thickness of the sample 4. That is, the more appropriate the measurement state is, the larger and sharper the peak appears in the power spectrum. Therefore, the measurement reliability can be calculated according to the size or sharpness of the peak.

[0156] For example, as shown in FIG. 24, the area indicated by the peak appearing at the position corresponding to the film thickness of sample 4 (peak area) and the area of the other part (noise area) are calculated, and the ratio of the calculated areas may be used as the measurement reliability. Specifically, the measurement reliability can be calculated according to the following formula.

[0157] Measurement reliability = Peak area / Noise area Alternatively, any of the following formulas may be adopted.

[0158] Measurement reliability = Peak area / (Peak area + Noise area) Measurement reliability = (Peak area - Noise area) / (Peak area + Noise area) Furthermore, the measurement reliability may be calculated based on the height of the peak (the magnitude of the power). Specifically, the measurement reliability can be calculated according to any of the following formulas.

[0159] Measurement reliability = Peak height / Noise height Measurement reliability = Peak height / (Peak height + Noise height) Measurement reliability = (Peak height - Noise height) / (Peak height + Noise height) In this way, when calculating the film thickness of the sample by the FFT method, the measurement reliability can be calculated based on the magnitude of the peak appearing in the calculated power spectrum.

[0160] (c2: Method for calculating measurement reliability by optimization method) Next, a method suitable for calculating the film thickness by the optimization method will be described.

[0161] The optimization method is a method of fitting the parameters of the model showing the spectral reflectance so as to match the actually measured spectral reflectance (or the wavenumber-converted reflectance R' obtained by converting the actually measured spectral reflectance).

[0162] Thus, in the optimization method, the film thickness of the sample is calculated by fitting the parameters of the model indicating the spectral reflectance or spectral transmittance so as to match the spectral reflectance or spectral transmittance calculated based on the observation light 24.

[0163] Based on how well the spectral reflectance (theoretical value) calculated by the model defined by the parameters determined by the optimization method matches the actually measured spectral reflectance (i.e., the degree of agreement with the actually measured spectral reflectance, or the degree of deviation from the actually measured spectral reflectance), the measurement reliability can be calculated.

[0164] More specifically, the correlation coefficient between the actually measured spectral reflectance and the spectral reflectance (theoretical value) calculated by the model defined by the parameters determined by the optimization method may be determined as the measurement reliability.

[0165] Alternatively, the reciprocal of the mean squared error between the actually measured spectral reflectance and the spectral reflectance (theoretical value) calculated by the model defined by the parameters determined by the optimization method may be determined as the measurement reliability.

[0166] Thus, when calculating the film thickness of the sample by the optimization method, the measurement reliability can be calculated based on the degree of agreement between the spectral reflectance calculated by the model defined by the determined parameters and the actually measured spectral reflectance. That is, when calculating the film thickness of the sample by the optimization method, the measurement reliability can be calculated based on the result of the determined fitting.

[0167] (c3: Method for calculating measurement reliability based on reflectance) FIG. 25 is a diagram for explaining another example of a method for calculating the measurement reliability in the optical measurement system 1 according to the present embodiment.

[0168] FIG. 25(A) shows an example of spectral reflectance when the measurement state is poor, and FIG. 25(B) shows an example of spectral reflectance when the measurement state is appropriate. As shown in FIG. 25, in an appropriate measurement state, the amplitude of the spectral reflectance (the difference between the maximum value and the minimum value of the reflectance) becomes relatively large. Therefore, the measurement reliability may be calculated based on the magnitude of the amplitude of the spectral reflectance. For example, based on the amplitude of the spectral reflectance measured with the reference cap 30 attached, the ratio to the reference amplitude may be calculated as the measurement reliability.

[0169] In this way, the measurement reliability can be calculated based on the measured amplitude of the spectral reflectance without depending on the algorithm for calculating the film thickness of the sample.

[0170] Also, the measurement reliability may be calculated from the value of the reflectance (amplitude reflectance). For example, the reflectance may be output as the measurement reliability as it is, or the reflectance may be input into a predetermined function (for example, a function whose output increases monotonically with respect to the reflectance) to calculate the measurement reliability.

[0171] When the angle or distance of the probe 200 with respect to the sample is not appropriate, or when the light diffusion on the sample surface is large, etc., the calculated reflectance (amplitude reflectance) becomes small, which means that the measurement reliability is low.

[0172] In this way, the measurement reliability can be calculated based on the magnitude of the measured reflectance (amplitude reflectance) without depending on the algorithm for calculating the film thickness of the sample.

[0173] Furthermore, the measurement reliability may be calculated from the variation of the reflectance (amplitude reflectance). For example, when the user's grip of the probe 200 is not stable and the angle or distance of the probe 200 fluctuates, or when there is a fine film thickness distribution on the sample surface, etc., the variation of the calculated reflectance (amplitude reflectance) becomes large, which means that the measurement reliability is low.

[0174] FIG. 26 is a diagram for explaining still another example of a method for calculating measurement reliability in the optical measurement system 1 according to the present embodiment.

[0175] FIG. 26(A) shows an example of the reflectance when the measurement is unstable, and FIG. 26(B) shows an example of the reflectance when the measurement is stable. As shown in FIG. 26, when the measurement is stable, the measured reflectance is also stable, so the variation becomes relatively small. Therefore, the measurement reliability may be calculated based on the magnitude of the variation in the reflectance.

[0176] More specifically, the measurement reliability may be calculated from the standard deviation or variance of the reflectance for a predetermined number of times from the most recent measurement.

[0177] In this way, the measurement reliability can be calculated based on the variation in the measured reflectance (amplitude reflectance) without depending on the algorithm for calculating the film thickness of the sample.

[0178] (c4: Method for calculating measurement reliability based on reference signal) The measurement reliability may be calculated based on the reference signal, which is the observation light 24 measured with the reference cap 30 attached to the probe 200.

[0179] For example, if there is deterioration of the light source 102 due to use or the like, the amount of light of the measurement light generated by the light source 102 decreases. In such a state, it can be considered that the measurement reliability is reduced. Therefore, the measurement reliability may be calculated based on the magnitude of the reference signal before or immediately after product shipment and the magnitude of the reference signal when actually measuring.

[0180] More specifically, the ratio of the magnitude of the reference signal when actually measuring to the magnitude of the reference signal before or immediately after product shipment may be calculated as the measurement reliability.

[0181] In this way, regardless of the algorithm for calculating the film thickness of the sample, the measurement reliability can be calculated based on the magnitude of the measured reference signal.

[0182] (c5: Method for calculating measurement reliability based on variation in measurement results) The measurement reliability may be calculated from the variation in the measurement results (e.g., film thickness). For example, when the grip of the user's probe 200 is not stable and the angle or distance of the probe 200 fluctuates, or when there is a fine film thickness distribution on the sample surface, etc., the variation in the measured or calculated measurement results will be large, which means low measurement reliability.

[0183] Similar to FIGS. 26(A) and 26(B) described above, when the measurement is stable, the measured or calculated measurement results are also stable, so the variation becomes relatively small. Therefore, the measurement reliability may be calculated based on the magnitude of the variation in the measured or calculated measurement results.

[0184] More specifically, the measurement reliability may be calculated from the standard deviation or variance of the measurement results for a predetermined number of times from the most recent measurement.

[0185] In this way, regardless of the algorithm for calculating the film thickness of the sample, the measurement reliability can be calculated based on the variation in the measured or calculated measurement results.

[0186] (c6: Method for using multiple types of measurement reliability) As described above, the measurement reliability can be calculated by multiple methods. Therefore, multiple measurement reliabilities calculated by different methods may be combined and calculated as the final measurement reliability. In this case, after normalizing the multiple measurement reliabilities of the object, they may be simply averaged to calculate the final measurement reliability.

[0187] Alternatively, for a plurality of measurement reliabilities of interest, they may be multiplied by their respective corresponding weighting factors to calculate the final measurement reliability. Further alternatively, the weighting factor may be changed according to conditions.

[0188] In this way, by using multiple types of measurement reliabilities to determine the final measurement reliability, the accuracy of the measurement reliability can be improved.

[0189] <D. Measurement Mode of Film Thickness> In the optical measurement system 1 according to the present embodiment, the following measurement modes may be implemented by using the measurement reliability as described above.

[0190] (d1: Search Support Mode) The search support mode is a measurement mode that makes it easier for the user to find an appropriate measurement state by calculating the measurement reliability in real time and notifying the user of the calculated measurement reliability.

[0191] FIG. 27 is a diagram showing an example of the spectral reflectance measured in each state of the probe 200 shown in FIG. 21. In the states where the film thickness measurement shown in FIGS. 27(A) and 27(C) is unstable, the amplitude of the measured spectral reflectance also becomes small. On the other hand, in an appropriate measurement state as shown in FIG. 27(B), the amplitude of the measured spectral reflectance also becomes large.

[0192] The user changes the angle, distance, and position (measurement position) of the probe 200 with respect to the measurement surface of the sample 4 in a state where the measurement light 22 is irradiated from the probe 200. The measurement device 100 calculates the spectral reflectance from the observation light 24 generated in the sample 4 and repeatedly performs a process of calculating the film thickness of the sample 4 through Fourier transform or the like. At the same time, the measurement device 100 also calculates the measurement reliability. Further, the measurement device 100 sequentially notifies the user of the calculated measurement reliability.

[0193] The notification of the measurement reliability to the user may be in any method, but a notification sound indicating the measurement reliability may be used so that the user can easily recognize the measurement reliability while holding and scanning the probe 200. For example, as follows, the height of the measurement reliability may be associated with the generation cycle or generation frequency of the notification sound.

[0194] Measurement reliability: Low Pi (silent) Pi Measurement reliability: Medium Pip (silent) Pip Measurement reliability: High Pipi (silent) Pipi In this way, a notification sound corresponding to the height of the measurement reliability may be generated. With such a notification sound, the user can grasp the measurement reliability in real time, so that the probe 200 can be adjusted to an appropriate angle, distance, and position (measurement position). By such adjustment, the film thickness of the sample 4 in an appropriate measurement state can be obtained.

[0195] Note that when the user determines an appropriate measurement state, the user may perform an operation on the operation unit 108 (for example, the trigger switch). The measuring device 100 outputs or stores the film thickness at the time when the operation unit 108 is operated by the user as an appropriate measurement result.

[0196] FIG. 28 is a diagram for explaining the processing in the search support mode of the optical measurement system 1 according to the present embodiment. Referring to FIG. 28, the user adjusts the angle, distance, and position (measurement position) while holding the probe 200 while confirming the measurement reliability by the notification sound 38. At this time, it is assumed that the measurement light 22 is continuously or intermittently irradiated from the probe 200. Then, the user maintains the probe 200 in a state where it is determined that the measurement reliability is sufficiently high and measures the film thickness of the sample 4.

[0197] By using the measurement mode as described above, the user can measure the film thickness of the sample 4 in an appropriate measurement state.

[0198] FIG. 29 is a flowchart showing a processing procedure in the search support mode of the optical measurement system 1 according to the present embodiment. Each step shown in FIG. 29 is typically realized by the processor 112 of the arithmetic processing unit 110 of the measurement device 100 executing the measurement program 124.

[0199] Referring to FIG. 29, when the measurement start is instructed (YES in step S100), the measurement device 100 gives a drive command to the light source 102 to activate the irradiation of the measurement light 22 from the light source 102 (step S102). In this way, the measurement device 100 irradiates the sample 4 with the measurement light 22 generated by the light source 102 through the probe 200 that can be arranged at an arbitrary position.

[0200] Then, the measurement device 100 calculates the film thickness of the sample 4 based on the detection result (intensity for each wavelength of the observation light 24) output when the observation light 24 from the sample 4 enters the spectroscopic measurement unit 104 (step S104). In this way, the measurement device 100 irradiates the sample 4 with the measurement light 22 and receives the reflected light (or transmitted light) generated as the observation light by the spectroscopic measurement unit 104, and calculates the film thickness of the sample 4 from the spectroscopic reflectance (or spectroscopic transmittance) calculated based on the detection result by the spectroscopic measurement unit 104.

[0201] Also, the measurement device 100 calculates the measurement reliability based on the data used in the process of calculating the film thickness of the sample 4 (step S106). In this way, the measurement device 100 calculates the measurement reliability indicating how appropriately the calculated film thickness is measured. Then, the measurement device 100 generates a notification sound corresponding to the calculated high measurement reliability (step S108).

[0202] When the output of the measurement result is instructed by a trigger switch or the like (YES in step S110), the measurement device 100 determines the film thickness of the sample 4 calculated in the current calculation cycle as the measurement result (step S112). If the output of the measurement result is not instructed (NO in step S110), the process of step S112 is skipped.

[0203] When the measurement device 100 is instructed to end the measurement (YES in step S114), it ends the film thickness measurement process. Otherwise (NO in step S114), it repeats the processes from step S104 and below.

[0204] By using the search support mode as described above, the user can search for an appropriate measurement state.

[0205] (d2: Automatic measurement mode) The automatic measurement mode is a measurement mode that automatically extracts measurement results with high measurement reliability from the start to the end of the measurement.

[0206] The user changes the angle, distance, and position (measurement position) of the probe 200 with respect to the measurement surface of the sample 4 while the measurement light 22 is being irradiated from the probe 200. The measurement device 100 repeatedly calculates the spectral reflectance from the observation light 24 generated in the sample 4 and calculates the film thickness of the sample 4 through processes such as Fourier transform. Additionally, the measurement device 100 calculates the measurement reliability corresponding to each film thickness.

[0207] When a series of film thickness measurements is completed, the measurement device 100 determines, as the measurement result, the one with the corresponding high measurement reliability among the calculated film thicknesses.

[0208] Figure 30 is a diagram for explaining the process in the automatic measurement mode of the optical measurement system 1 according to the present embodiment. Referring to Figure 30, the measurement device 100 calculates the film thickness of the sample 4 and the corresponding measurement reliability from the start to the end of the measurement, and extracts one or more measurement reliabilities that satisfy a predetermined condition (for example, high measurement reliability) among the calculated measurement reliabilities. The measurement device 100 determines the film thickness corresponding to the extracted one or more measurement reliabilities as the measurement result.

[0209] As shown in FIG. 30, the maximum value of the measurement reliability (i.e., one measurement reliability) calculated from the start to the end of the measurement may be extracted, or one or more measurement reliabilities exceeding a predetermined threshold may be extracted. Also, even when extracting the maximum value of the measurement reliability, it may be an additional condition that the maximum value of the measurement reliability exceeds a predetermined threshold.

[0210] In this way, any method may be adopted for extracting the measurement reliability.

[0211] FIG. 31 is a flowchart showing the processing procedure in the automatic measurement mode of the optical measurement system 1 according to the present embodiment. Each step shown in FIG. 31 is typically realized by the processor 112 of the arithmetic processing unit 110 of the measurement device 100 executing the measurement program 124.

[0212] Referring to FIG. 31, when the measurement device 100 is instructed to start the measurement (YES in step S200), it gives a drive command to the light source 102 to activate the irradiation of the measurement light 22 from the light source 102 (step S202). In this way, the measurement device 100 irradiates the sample 4 with the measurement light 22 generated by the light source 102 through the probe 200 that can be arranged at an arbitrary position.

[0213] Then, the measurement device 100 calculates the film thickness of the sample 4 based on the detection result (intensity for each wavelength of the observation light 24) output when the observation light 24 from the sample 4 is incident on the spectroscopic measurement unit 104 (step S204). In this way, the measurement device 100 irradiates the sample 4 with the measurement light 22 and receives the reflected light (or transmitted light) generated as the observation light by the spectroscopic measurement unit 104, and calculates the film thickness of the sample 4 from the spectroscopic reflectance (or spectroscopic transmittance) calculated based on the detection result by the spectroscopic measurement unit 104.

[0214] Also, the measuring device 100 calculates the measurement reliability based on the data used in the process of calculating the film thickness of the sample 4 (step S206). In this way, the measuring device 100 calculates the measurement reliability indicating how appropriately the calculated film thickness is measured.

[0215] When the measuring device 100 is instructed to end the measurement (YES in step S208), it executes the processes from step S210 and below. Otherwise (NO in step S208), it repeats the processes from step S204 and below.

[0216] In step S208, the measuring device 100 extracts one or more measurement reliabilities that satisfy a predetermined condition among the measurement reliabilities calculated from the start to the end of the measurement (step S210). Then, the measuring device 100 outputs the film thickness corresponding to each of the extracted one or more measurement reliabilities as a measurement result (step S212). Then, the process ends.

[0217] By using the automatic measurement mode as described above, the user can measure the film thickness in an appropriate measurement state without being conscious of the measurement reliability and the like.

[0218] (d3: Automatic Measurement Mode with Search Support) The automatic measurement mode with search support is a measurement mode that notifies the user of the improvement of the measurement reliability and automatically extracts measurement results with high measurement reliability from the start to the end of the measurement.

[0219] The user changes the angle, distance, and position (measurement position) of the probe 200 with respect to the measurement surface of the sample 4 while the measurement light 22 is being irradiated from the probe 200. The measuring device 100 repeatedly calculates the spectral reflectance from the observation light 24 generated in the sample 4 and calculates the film thickness of the sample 4 through processes such as Fourier transform. In addition, the measuring device 100 also calculates the measurement reliability corresponding to each film thickness. Further, the measuring device 100 sequentially notifies the user whether the calculated measurement reliability is in the improving direction.

[0220] Notification of whether the measurement reliability for the user is improving may be in any method, but a notification sound indicating the level of measurement reliability may be used so that the user can easily recognize the improvement in measurement reliability while holding and scanning the probe 200. For example, the notification sound may be generated only when the measurement reliability changes in a direction higher than the previous measurement reliability. Further, the generated notification sound may also correspond to the calculated level of measurement reliability.

[0221] Alternatively, by generating a notification sound when the measurement reliability improves and generating another notification sound when the measurement reliability decreases, the user can easily recognize whether the measurement reliability is improving by their own adjustment.

[0222] When a series of film thickness measurements is completed, the measuring device 100 determines, as the measurement result, the calculated film thickness with a corresponding high measurement reliability.

[0223] FIG. 32 is a diagram for explaining the processing in the automatic measurement mode with search support of the optical measurement system 1 according to the present embodiment. Referring to FIG. 32, the measuring device 100 calculates the film thickness of the sample 4 and the corresponding measurement reliability from the start to the end of the measurement, and notifies the user when the calculated measurement reliability improves.

[0224] When a series of film thickness measurements is completed, the measuring device 100 extracts one or more measurement reliabilities that satisfy a predetermined condition (for example, high measurement reliability) from the calculated measurement reliabilities. The measuring device 100 determines, as the measurement result, the film thickness corresponding to the determined one or more measurement reliabilities.

[0225] As shown in FIG. 32, peaks appearing in the measurement reliability calculated from the start to the end of the measurement may be extracted, or one or more measurement reliabilities exceeding a predetermined threshold may be extracted. Further, even when extracting peaks appearing in the measurement reliability, it may be an additional condition that the peak value exceeds a predetermined threshold.

[0226] Thus, any method may be adopted for extracting the measurement reliability.

[0227] FIG. 33 is a flowchart showing the processing procedure in the automatic measurement mode with search support of the optical measurement system 1 according to the present embodiment. Each step shown in FIG. 33 is typically realized by the processor 112 of the arithmetic processing unit 110 of the measuring device 100 executing the measurement program 124.

[0228] Referring to FIG. 33, when the measuring device 100 is instructed to start measurement (YES in step S300), it gives a drive command to the light source 102 to activate the irradiation of the measurement light 22 from the light source 102 (step S302). Thus, the measuring device 100 irradiates the sample 4 with the measurement light 22 generated by the light source 102 through the probe 200 that can be arranged at an arbitrary position.

[0229] Then, the measuring device 100 calculates the film thickness of the sample 4 based on the detection result (intensity for each wavelength of the observation light 24) output when the observation light 24 from the sample 4 enters the spectroscopic measurement unit 104 (step S304). Thus, the measuring device 100 irradiates the sample 4 with the measurement light 22, receives the reflected light (or transmitted light) generated as the observation light by the spectroscopic measurement unit 104, and calculates the film thickness of the sample 4 from the spectroscopic reflectance (or spectroscopic transmittance) calculated based on the detection result by the spectroscopic measurement unit 104.

[0230] Further, the measuring device 100 calculates the measurement reliability based on the data used in the process of calculating the film thickness of the sample 4 (step S306). Thus, the measuring device 100 calculates the measurement reliability indicating how appropriately the calculated film thickness is measured.

[0231] If the calculated measurement reliability is in the improving direction (YES in step S308), the measuring device 100 generates a notification sound indicating that the measurement reliability is in the improving direction (step S310). If the calculated measurement reliability is not in the improving direction (NO in step S308), the process of step S310 may be skipped.

[0232] Then, when the measuring device 100 is instructed to end the measurement (YES in step S312), it executes the processes from step S314 and below. Otherwise (NO in step S312), it repeats the processes from step S304 and below.

[0233] In step S310, the measuring device 100 extracts one or more measurement reliabilities that satisfy a predetermined condition among the measurement reliabilities calculated from the start to the end of the measurement (step S314). Then, the measuring device 100 outputs the film thickness corresponding to each of the extracted one or more measurement reliabilities as a measurement result (step S316). Then, the process ends.

[0234] By using the automatic measurement mode with search support as described above, the user can search for an appropriate measurement state.

[0235] (d4: Method of notification) In the above description, a notification form in which the height of the measurement reliability is associated with the generation cycle or frequency of the notification sound is exemplified, but it is not limited to this, and any notification method can be adopted.

[0236] When notifying the measurement reliability by sound (that is, when the user recognizes the measurement reliability by hearing), one or more of volume, pitch, and timbre may be changed according to the height of the calculated measurement reliability. The user can easily recognize the change in the measurement reliability by the change in any of the volume, pitch, and timbre of the notification sound.

[0237] Furthermore, not limited to notification by sound, notification by vibration, light, image, etc. can also be adopted.

[0238] For example, when notifying the measurement reliability by vibration (that is, when the user recognizes the measurement reliability by touch), a vibrator may be provided in the measuring device 100 and / or the probe 200, and one or more of the vibration intensity, vibration period, and vibration interval of the vibrator may be changed according to the calculated height of the measurement reliability. The user can easily recognize the change in the measurement reliability by the change in the vibration felt by himself / herself.

[0239] Also, when notifying the measurement reliability by light or an image (that is, when the user recognizes the measurement reliability visually), an arbitrary light-emitting device may be provided in the measuring device 100 and / or the probe 200, and the light-emitting state of the light-emitting device may be changed according to the calculated height of the measurement reliability. That is, at least one of light and an image indicating the measurement reliability may be output from the output unit 106. The user can easily recognize the change in the measurement reliability by the light or image that enters the eyes.

[0240] FIG. 34 is a schematic diagram showing an example of a notification form of measurement reliability in the optical measurement system 1 according to the present embodiment. FIGS. 34(A) to 34(C) show an example of a notification form when a display 1060 is adopted as the output unit 106 of the measuring device 100.

[0241] On the display 1060 of the measuring device 100 shown in FIG. 34(A), a measured value 1062 of the film thickness and a status bar 1064 indicating the measurement reliability are displayed. The user can obtain the measured value 1062 of the film thickness while recognizing the measurement reliability by checking the status bar 1064 indicating the measurement reliability.

[0242] On the display 1060 of the measuring device 100 shown in FIG. 34(B), a measured value 1062 of the film thickness and a numerical value 1066 indicating the measurement reliability are displayed. The user can obtain the measured value 1062 of the film thickness while recognizing the measurement reliability by checking the numerical value 1066 indicating the measurement reliability.

[0243] On the display 1060 of the measuring device 100 shown in FIG. 34(C), the measured film thickness value 1062 is displayed, and the measuring device 100 is provided with an indicator 1068 indicating the measurement reliability. The indicator 1068 lights up by a number corresponding to the calculated high measurement reliability. The user can obtain the measured film thickness value 1062 while recognizing the measurement reliability by checking the indicator 1068 indicating the measurement reliability.

[0244] The measurement reliability can be notified to the user in any form, not limited to the notification forms shown in FIGS. 34(A) to 34(C).

[0245] <E. Functional Block Diagram> FIG. 35 is a schematic diagram showing an example of the functional configuration provided by the optical measurement system 1 according to the present embodiment. Each function shown in FIG. 35 is typically realized by the processor 112 of the arithmetic processing unit 110 of the measuring device 100 executing the measurement program 124.

[0246] Referring to FIG. 35, the measuring device 100 includes, as a functional configuration, a buffer 150, a wave number conversion unit 152, a Fourier transform unit 154, a peak search unit 156, a film thickness determination unit 158, a measurement reliability calculation unit 160, and an output processing unit 162.

[0247] The buffer 150 stores the detection results (intensity for each wavelength of the observation light 24) from the spectroscopic measurement unit 104.

[0248] The wave number conversion unit 152 calculates the spectroscopic reflectance from the intensity for each wavelength of the observation light 24 stored in the buffer 150, and calculates the wave number conversion reflectance from the calculated spectroscopic reflectance.

[0249] The Fourier transform unit 154 Fourier-transforms the wave number conversion reflectance calculated by the wave number conversion unit 152.

[0250] The peak search unit 156 searches for peaks included in the power spectrum calculated by the Fourier transform performed by the Fourier transform unit 154, and outputs the position (film thickness) of the power spectrum corresponding to the searched peak. That is, the peak search unit 156 corresponds to a film thickness calculation unit that calculates the film thickness of the sample from the spectral reflectance (or spectral transmittance) calculated based on the detection result by the spectroscopic measurement unit 104.

[0251] The measurement reliability calculation unit 160 calculates a measurement reliability indicating how appropriately the film thickness calculated by the peak search unit 156 is measured. More specifically, the measurement reliability calculation unit 160 calculates the measurement reliability based on the power spectrum calculated by the Fourier transform performed by the Fourier transform unit 154.

[0252] When a predetermined condition is satisfied, the film thickness determination unit 158 determines the film thickness output from the peak search unit 156 as the measurement result. The predetermined condition may include that the user has operated the operation unit 108, that the measurement reliability in a predetermined period is the maximum value, that the measurement reliability exceeds a predetermined threshold value, and the like. Thus, the film thickness determination unit 158 typically determines the film thickness at the time when the measurement reliability satisfies the predetermined condition as the measurement result.

[0253] The output processing unit 162 is responsible for the process of outputting the film thickness output from the peak search unit 156, the measurement reliability output from the measurement reliability calculation unit 160, the measurement result (film thickness) output from the film thickness determination unit 158, etc. from the output unit 106. The output processing unit 162 notifies the user of the measurement reliability calculated by the measurement reliability calculation unit 160 via the output unit 106.

[0254] Note that FIG. 35 shows a configuration example in the case of calculating the film thickness by the FFT method as a typical example. However, when measuring the film thickness by the optimization method, a fitting unit that fits a model including the film thickness of the sample as a parameter and the actually measured reflectance (or transmittance) may be provided.

[0255] <F. Modification Example> In the above description, a configuration example has been described in which the measuring device 100 of the optical measurement system 1 executes necessary processes. However, the present invention is not limited to this. For example, the processes may be shared among a plurality of processing devices, or a part of the processes may be assigned to the probe 200. Further, computing resources (so-called cloud) on a network (not shown) may be made to be responsible for all or part of the necessary processes.

[0256] When many computing resources are available, machine learning may be performed using measurement results acquired in the past and / or measurement results acquired by other optical measurement systems 1, and an optimal condition related to film thickness measurement may be notified to the user using the learned model obtained by the machine learning.

[0257] <G. Summary> In the optical measurement system according to the present embodiment, since the film thickness of the sample is optically calculated based on the observation light acquired through the probe that can be arranged at an arbitrary position, the measurement accuracy of the film thickness can be improved.

[0258] Further, in the optical measurement system according to the present embodiment, since the measurement reliability indicating how appropriately the calculated film thickness is measured is also calculated, the film thickness of the sample can be measured more appropriately.

[0259] Furthermore, since the optical measurement system according to the present embodiment can measure by arranging an arbitrary sample with the probe that can be arranged at an arbitrary position, the film thickness can be easily measured at a production site, a manufacturing line, or the like. Also, even a sample having a curved surface or a sample having a complicated shape can be easily measured.

[0260] It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0261] 1, 1A, 1B optical measurement system, 4 samples, 10, 20, 52, 54 optical fibers, 12, 14 branching fibers, 16 branching section, 22 measurement light, 24 observation light, 28 coupler, 30 reference cap, 32, 216 mirrors, 38 notification sound, 40 air layer, 41 coating layer, 42 substrate layer, 100, 100A, 100B measurement devices, 102 light source, 104 spectral measurement unit, 106 output unit, 108 operation unit, 110 arithmetic processing unit, 112 processor, 114 main memory, 116 internal interface, 117 general-purpose interface, 118 network interface, 120 storage, 122 operating system, 124 measurement program, 126 detection result, 128 measurement result, 130 power supply unit, 132 battery, 134 communication unit, 136 communication processing unit, 150 buffer, 152 wave number conversion unit, 154 Fourier transform unit, 156 peak search unit, 158 film thickness determination unit, 160 measurement reliability calculation unit, 162 output processing unit, 200, 200C, 200D, 200E, 200F, 200G, 200H, 200I, 200J, 200K, 200L, 200M probes, 200B high-functional probe, 202 light transmitting and receiving unit, 204 light guiding path, 210, 212 attachments, 214, 218 support members, 220, 222 lenses, 226 flexible section, 228 contact section, 230 rubber packing, 234 needle section, 1060 display, 1062 measured value, 1064 status bar, 1066 numerical value, 1068 indicator.

Claims

1. An optical measurement system for measuring the film thickness, which is the thickness of a layer contained in a sample, comprising: a measuring device that can be held by one hand of a user; a probe that can be held by the other hand of the user; an optical fiber that optically connects the measuring device and the probe, wherein the measuring device includes a light source; the probe is configured to irradiate the sample with light generated by the light source and guided by the optical fiber as measurement light, and to guide the reflected light generated by the sample to the optical fiber as observation light; the measuring device further includes: a spectroscopic measurement unit that outputs the intensity for each wavelength of the observation light guided by the optical fiber; a film thickness calculation unit that calculates the film thickness of the sample from the spectroscopic reflectance calculated based on the intensity for each wavelength of the observation light; The optical fiber includes a first optical fiber optically connected to the measuring device, a second optical fiber optically connected to the probe, and a coupler that detachably connects the first optical fiber and the second optical fiber.

2. The optical measurement system according to claim 1, wherein the probe connected via the coupler is configured to be exchangeable from among a plurality of types of probes.

3. The measuring device has a shape that can be held by the palm of one hand of the user, The optical measurement system according to claim 1 or 2, wherein the probe has a shape that can be held by some fingers of the other hand of the user.

4. The first optical fiber includes: a first branched fiber optically connected to the light source; a second branched fiber optically connected to the spectroscopic measurement unit; a branching portion that converges the first branched fiber and the second branched fiber. The optical measurement system according to any one of claims 1 to 3.

5. The end face of the probe is a flat circle, In the central portion of the end face of the probe, a depression through which the measurement light and the observation light pass is formed. The optical measurement system according to any one of claims 1 to 4.

6. The sample is cylindrical, The probe includes a pair of support members for supporting the sample, The pair of support members are arranged in a V shape in a cross-sectional view. The optical measurement system according to any one of claims 1 to 5, wherein a space through which the measurement light and the observation light pass is provided between the pair of support members. **Claim 7** The optical measurement system according to any one of claims 1 to 6, wherein the measurement device includes a display at a position visible to the user while being held by the user with one hand. **Claim 8** The optical measurement system according to claim 7, wherein the measurement device displays, on the display, a measurement reliability indicating how appropriately the calculated film thickness is measured, together with the calculated film thickness.

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