JP2017133869A - Thickness measuring device and thickness measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thickness measuring device and thickness measuring method capable of accurately measuring the thickness of a sample.SOLUTION: A thickness measuring device comprises: a first transmissive member having a first reference surface; a second transmissive member provided opposite the first transmissive member and having a second reference surface; a first light projecting part for applying light from a light source to a sample positioned between the first transmissive member and the second transmissive member via the first reference surface; a first light receiving part for receiving reflected light from the first reference surface and receiving via the first reference surface, reflected light from the sample; a second light projecting part for applying light from a light source to the sample via the second reference surface; a second light receiving part for receiving reflected light from the second reference surface and receiving via the second reference surface, reflected light from the sample; and a spectroscopic part for spectrally decomposing the reflected light received by the first light receiving part and the reflected light received by the second light receiving part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thickness measuring apparatus and a thickness measuring method, and more particularly to a thickness measuring apparatus and a thickness measuring method for measuring the thickness of a sample using reflected light.

  In recent years, displacement measuring devices that measure distance using light have been developed. For example, Japanese Unexamined Patent Application Publication No. 2009-270939 (Patent Document 1) discloses the following configuration. That is, the optical displacement meter includes a broadband light source device that generates broadband light as detection light for measurement, and a condensing lens having a flat exit-side end surface that condenses the detection light and emits it toward the measurement object. The distance between the measurement object and the exit-side end face is obtained by dispersing the reflected light from the measurement object and the reflected light from the exit-side end face incident on the condenser lens to obtain the frequency of the characteristic curve of the wavelength distribution. The condensing lens is a lens that emits the detection light whose irradiation spot becomes wider as the distance from the end face on the emission side increases.

  Japanese Patent Laying-Open No. 2014-115242 (Patent Document 2) discloses the following configuration. That is, the displacement measuring device includes a point light source that emits light having a diffused spectrum, and an optical that causes axial chromatic aberration in the light and condenses the light causing the axial chromatic aberration on a measurement object. Among the light collected by the element and the optical element, an aperture that passes through the light to be focused on the measurement object, and a spectrum of the light that has passed through the aperture is obtained, based on the peak wavelength of the spectrum, A measurement unit that obtains a distance between the optical element and the measurement object, the measurement unit obtains a spectral reflection characteristic of the measurement object, and uses the obtained spectral reflection characteristic to The distance is determined so as to reduce the error caused by the reflection characteristics in the distance measurement.

  Japanese Patent Laying-Open No. 2010-121977 (Patent Document 3) discloses the following configuration. That is, the optical displacement meter includes a detection light generating unit that generates detection light, a reference surface that reflects a part of the detection light and transmits another part of the detection light to the inspection object side, and the reference A spectroscopic unit that splits the interference light composed of the reflected light from the surface and the reflected light from the inspection object; and a light intensity distribution generating unit that receives the interference light after the spectrum and generates a light intensity distribution related to the wave number of the interference light. The light intensity maximum point extraction means that repeats the conversion of the light intensity distribution relating to the wave number into the light intensity distribution relating to the spatial frequency of the light intensity relative to the wave number, and extracting the maximum point of the light intensity distribution relating to the spatial frequency at a constant time interval. Phase determining means for determining a phase of a frequency component corresponding to the spatial frequency of the maximum point of the light intensity distribution relating to the wave number, and a displacement amount determination for determining a displacement amount of the inspection object based on the phase. Means for determining the relative phase of the frequency component within a range of 360 degrees, the relative phase determination means based on the determination result by the relative phase determination means and the previous determination result. An absolute phase calculating means for connecting the phases to obtain an absolute phase; and a phase reference updating means for updating the reference point of the absolute phase based on a reset instruction. Based on this, the amount of displacement is determined.

JP 2009-270939 A JP 2014-115242 A JP 2010-121977 A

  When measuring the thickness of the sample using the techniques described in Patent Documents 1 to 3, for example, the thickness of the sample is measured from the measurement result of the distance to the grounded sample and the measurement result of the distance to the ground plane. A method is conceivable.

  However, when the surface of the sample is uneven, or the sample is distorted or warped, a gap is generated between the surface of the sample on the ground surface side and the ground surface. In such a case, it may be difficult to accurately measure the thickness of the sample.

  This invention was made in order to solve the above-mentioned subject, The objective is to provide the thickness measuring apparatus and thickness measuring method which can measure the thickness of a sample correctly.

  (1) In order to solve the above-mentioned problem, a thickness measuring apparatus according to an aspect of the present invention is provided with a first transmission member having a first reference surface and facing the first transmission member, A second transmission member having a second reference surface and light from a light source are irradiated to the sample positioned between the first transmission member and the second transmission member through the first reference surface. And a first light receiving unit for receiving reflected light from the first reference surface and receiving reflected light from the sample through the first reference surface A second light projecting unit for irradiating the sample with light from the light source via the second reference surface, and receiving reflected light from the second reference surface, and from the sample A second light receiving part for receiving reflected light through the second reference surface, and the light received by the first light receiving part; Shako, and and a spectroscopic portion for dispersing the reflected light received by said second light receiving portion.

  In this way, light is irradiated to both sides of the sample through each reference surface, and the reflected light from the surfaces on both sides of the sample is caused to interfere with the reflected light from the corresponding reference surface, respectively, to perform spectroscopy. Even when the surface is uneven or the sample is distorted or warped, the distance between the surface on both sides of the sample and the corresponding reference surface can be calculated based on the spectroscopic result. For example, the thickness of the sample can be accurately calculated from the calculated distances and the distances between the reference surfaces. Therefore, the thickness of the sample can be accurately measured.

  (2) Preferably, the spectroscopic unit includes one spectroscope, and the thickness measuring device further includes light received by the first light receiving unit and light received by the second light receiving unit. Is provided with an optical system for guiding the light to the spectrometer.

  With the configuration using such an optical system, the number of expensive spectrometers can be minimized, so that the manufacturing cost of the thickness measuring device can be reduced.

  (3) Preferably, the axis of the beam bundle of light irradiated from the first light projecting unit through the first reference surface to the sample, and the second reference from the second light projecting unit The axis of the beam bundle of light irradiated to the sample through the surface, the axis of the beam bundle of reflected light from the first reference surface received by the first light receiving unit, and the reflected beam from the sample The axis of the beam bundle, the axis of the beam bundle of the reflected light from the second reference surface received by the second light receiving unit, and the axis of the beam bundle of the reflected light from the sample are along each other.

  With such a configuration, the thickness of the sample can be accurately measured even when each reference surface is arranged non-parallel, for example, or when the sample is provided non-parallel to the reference surface.

  (4) Preferably, the spectroscopic unit includes one spectroscope, and the thickness measuring device further includes light received by the first light receiving unit and light received by the second light receiving unit. And an optical system for guiding reflected light from the sample to the spectrometer via the first reference surface, the first light receiving unit, and the optical system. The distance and the optical distance of the path of reflected light propagating from the sample to the spectroscope via the second reference surface, the second light receiving unit, and the optical system are set to be the same. Yes.

  With this configuration, the time required for the light reflected on the surfaces on both sides of the sample to reach the spectroscope can be made substantially the same, so that the reflected light reflected on each surface at almost the same timing can be obtained. Spectroscopy can be performed. Thereby, even when the sample is moving, the thickness of the sample can be accurately measured with a simple configuration.

  (5) Preferably, the thickness measurement apparatus further includes a first distance that is a distance between the first reference surface and the sample, and the second reference, based on a spectroscopic result by the spectroscopic unit. A calculation unit that calculates a second distance, which is a distance between a surface and the sample, wherein the calculation unit calculates the first distance from a distance between the first reference surface and the second reference surface. And the thickness of the sample is calculated by subtracting the second distance.

  As described above, the thickness of the sample can be calculated even if the sample is an opaque substance by the configuration in which the thickness of the sample is calculated from each distance that is a measurement result of the space outside the sample. In addition, the thickness of the sample can be easily calculated without recognizing physical property values such as the refractive index of the sample.

  (6) In order to solve the above problems, a thickness measuring method according to an aspect of the present invention is provided with a first transmission member having a first reference surface and facing the first transmission member, A second transmission member having a second reference surface and light from a light source are irradiated to the sample positioned between the first transmission member and the second transmission member through the first reference surface. And a first light receiving unit for receiving reflected light from the first reference surface and receiving reflected light from the sample through the first reference surface A second light projecting unit for irradiating the sample with light from the light source via the second reference surface, and receiving reflected light from the second reference surface, and from the sample A second light receiving part for receiving reflected light through the second reference surface, and the light received by the first light receiving part; A thickness measuring method using a thickness measuring device including incident light and a spectroscopic unit that splits reflected light received by the second light receiving unit, wherein the first reference is based on a spectroscopic result of the spectroscopic unit. Calculating a first distance that is a distance between a surface and the sample and a second distance that is a distance between the second reference surface and the sample; and the first reference surface and the first Calculating the thickness of the sample by subtracting the first distance and the second distance from an inter-surface distance that is a distance between the two reference surfaces.

  In this way, light is irradiated to both sides of the sample through each reference surface, and the reflected light from the surfaces on both sides of the sample is caused to interfere with the reflected light from the corresponding reference surface, respectively, to perform spectroscopy. Even when the surface is uneven or the sample is distorted or warped, the distance between the surface on both sides of the sample and the corresponding reference surface can be calculated based on the spectroscopic result. Then, the thickness of the sample can be accurately calculated from the calculated distances and the distances between the reference surfaces. Therefore, the thickness of the sample can be accurately measured. Also, by calculating the thickness of the sample from each distance that is a measurement result of the space outside the sample, the thickness of the sample can be calculated even if the sample is an opaque substance. In addition, the thickness of the sample can be easily calculated without recognizing physical property values such as the refractive index of the sample.

  (7) Preferably, in a state where the sample is not provided, light from a light source is irradiated from the first light projecting unit to the second reference surface via the first reference surface, Reflected light from one reference surface is received by the first light receiving unit, and reflected light from the second reference surface is received by the first light receiving unit through the first reference surface, The thickness measuring method further includes a step of calculating the inter-plane distance based on a spectral result of the reflected light received by the first light receiving unit in a state where the sample is not provided.

  With such a configuration, the inter-surface distance can be calculated using the same method as the calculation method of the first distance and the second distance. Therefore, the calculation accuracy is as high as the calculation accuracy of the first distance and the second distance. The distance between the planes can be calculated. Thereby, for example, the thickness of the sample can be calculated more accurately as compared with the case where the inter-surface distance is calculated using another method with low accuracy.

  According to the present invention, the thickness of the sample can be accurately measured.

FIG. 1 is a diagram showing a configuration of a thickness measuring apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of the probe in the thickness measuring apparatus according to the embodiment of the present invention. FIG. 3 is a diagram for explaining the function of the fiber junction in the thickness measuring apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of a power spectrum generated in the calculation unit in the thickness measuring apparatus according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of a power spectrum generated in the calculation unit in the thickness measuring apparatus according to the embodiment of the present invention. FIG. 6 is a flowchart defining an example of the procedure of a measurement method using the thickness measurement apparatus according to the embodiment of the present invention. FIG. 7 is a diagram illustrating a comparative example of probes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. Moreover, you may combine arbitrarily at least one part of embodiment described below.

  FIG. 1 is a diagram showing a configuration of a thickness measuring apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of the probe in the thickness measuring apparatus according to the embodiment of the present invention.

  Referring to FIGS. 1 and 2, thickness measuring apparatus 101 includes probes 1 and 2, a spectroscopic unit 3, a light source 4, an optical system 5, and a calculation unit 6. The probe 1 includes a lens system 51 and a transmission substrate (first transmission member) 61. The lens system 51 includes a lens 55 and a lens (first light projecting unit and first light receiving unit) 57. The transmissive substrate 61 has a surface (first reference surface) 65 and a surface 67. The probe 2 includes a lens system 52 and a transmission substrate (second transmission member) 62. The lens system 52 includes a lens 56 and a lens (second light projecting unit and second light receiving unit) 58. The transmissive substrate 62 has a surface (second reference surface) 66 and a surface 68. The spectroscopic unit 3 includes a spectroscope 41 and a data generation unit 42. The optical system 5 includes optical fibers 31, 32, 33, and 34 and a fiber junction 35.

  The light source 4 in the thickness measuring apparatus 101 is, for example, a laser that outputs light having a wide bandwidth. The light source 4 may be an LED (Light-Emitting Diode) or an incandescent bulb.

  The optical system 5 guides the light output from the light source 4 to the probes 1 and 2, for example. More specifically, the optical fiber 34 in the optical system 5 receives light from the light source 4 at an input end that is optically coupled to the light source 4, and transmits the received light to the fiber junction 35.

  FIG. 3 is a diagram for explaining the function of the fiber junction in the thickness measuring apparatus according to the embodiment of the present invention.

  Referring to FIG. 3, fiber junction 35 distributes light received from optical fiber 34 to optical fibers 31 and 32.

  Referring to FIGS. 1 and 2 again, the optical fiber 31 transmits the light from the light source 4 distributed by the fiber junction 35 to the lens system 51 in the probe 1. The optical fiber 32 transmits the light from the light source 4 distributed by the fiber junction 35 to the lens system 52 in the probe 2.

  In the thickness measurement apparatus 101, for example, the axis of the light projection beam bundle 71 of the light irradiated from the lens 57 through the surface 65 to the sample 151 and the light projection from the lens 58 through the surface 66 to the sample 151. From the axis of the light beam 72, the axis of the reflected beam bundle 73 of the reflected light from the surface 65 received by the lens 57, the axis of the reflected beam bundle 75 of the reflected light from the sample 151, and the surface 66 received by the lens 58. The axis of the reflected beam bundle 74 of the reflected light and the axis of the reflected beam bundle 76 of the reflected light from the sample 151 are along each other. Here, the axis of the light bundle is an axis along a light ray included in the parallel light bundle when the light bundle is a parallel light bundle, and when the light bundle is a divergent light beam or a convergent light beam, It is a symmetry axis of a cone having a side surface along a light ray included in the divergent ray bundle or the convergent ray bundle.

  More specifically, in the lens system 51, the lenses 55 and 57 are, for example, cylindrical convex lenses, and are provided so that the optical axes are along each other. Here, a virtual axis along the optical axis of the lenses 55 and 57 is defined as a reference axis 70.

  The lens 57 irradiates the sample 151 located between the transmissive substrate 61 and the transmissive substrate 62 through the surface 65 as the first light projecting unit.

  The sample 151 is disposed on a stage (not shown), and can move between the transmission substrate 61 and the transmission substrate 62 along a plane parallel to the surfaces 65 and 66. Here, a part of the sample 151 is located between the transmissive substrate 61 and the transmissive substrate 62. Note that the entire sample 151 may be located between the transmissive substrate 61 and the transmissive substrate 62.

  The lens 55 faces the end face 77 of the optical fiber 31 optically coupled with itself, and among the light bundles of light from the end face 77, a light projecting light bundle 71 that is a light bundle having the optical axis of the lens 55 as an axis. Is received and converted from a divergent beam to a parallel beam. Therefore, the axis of the projection light beam 71 is along the reference axis 70.

  The lens 57 is provided between the lens 55 and the transmission substrate 61, and is a surface that opposes the light from the light source 4 to the surface 65 by converting the projected light bundle 71 from the lens 55 into a convergent light bundle. Light is collected near the surface 81 of the sample 151 via the surface 65.

  The transmissive substrate 61 and the transmissive substrate 62 are provided to face each other. Specifically, the transmissive substrate 61 and the transmissive substrate 62 are provided facing each other. More specifically, the transmissive substrate 61 and the transmissive substrate 62 are provided such that the surface 65 that is the first reference surface and the surface 66 that is the second reference surface face each other.

  Note that the transmissive substrate 61 and the transmissive substrate 62 are not limited to the configuration in which the surface 65 and the surface 66 face each other, and may be provided to face each other.

  The transmissive substrate 61 and the transmissive substrate 62 are, for example, parallel plane substrates, and are transparent or translucent in the frequency band of light output from the light source 4. More specifically, the surface 65 and the surface 67 in the transmissive substrate 61 are, for example, flat and parallel to each other. The transmission substrate 61 is provided so that the normal line of the surface 65 is along the reference axis 70 and the surface 65 and the surface 67 are opposed to the surface 81 of the sample 151 and the lens 57, respectively.

  Moreover, the surface 66 and the surface 68 in the transmissive substrate 62 are, for example, flat and parallel to each other. The transmission substrate 62 is provided so that the normal of the surface 66 is along the reference axis 70 and the surface 66 and the surface 68 are opposed to the surface 82 of the sample 151 and the lens 58, respectively.

  The surface 65 and the surface 67 may be non-parallel to each other. Further, the surface 66 and the surface 68 may be non-parallel to each other. Further, the thickness measuring apparatus 101 may be configured to include a transmissive member having a shape other than a plate instead of the transmissive substrate 61 and the transmissive substrate 62.

  The lens 57 in the lens system 51 receives the reflected light from the surface 65 of the transmission substrate 61 and receives the reflected light from the sample 151 through the surface 65 as a first light receiving unit.

  More specifically, since the surface 65 is an interface between the transmission substrate 61 and the air layer, the surface 65 reflects light received from the lens 57. Further, the surface 81 of the sample 151 is an interface between the sample 151 and the air layer, and thus reflects light received from the lens 57 through the transmission substrate 61.

  The lens 57 receives a reflected light bundle 75, which is a light bundle having the optical axis of the lens 57 as an axis, among the light bundles of the light reflected by the sample 151 via the surface 65, and generates a parallel ray from the divergent ray bundle. Convert to a bunch. Accordingly, the axis of the reflected light bundle 75 is along the reference axis 70.

  The lens 57 receives a reflected light bundle 73 that is a light bundle having the optical axis of the lens 57 as an axis out of the light bundle reflected by the surface 65, and converts the divergent light bundle into a parallel light bundle. . Therefore, the axis of the reflected light bundle 73 is along the reference axis 70. In this example, since the distance between the surface 65 and the surface 81 is shorter than the distance between the lens 57 and the surface 81, the reflected light flux 73 is approximated when converted into a parallel light flux by the lens 57. ing.

  The lens 55 condenses the reflected light from the sample 151 via the surface 65 onto the end face 77 of the optical fiber 31 by converting the reflected light bundle 75 from the lens 57 into a convergent light bundle, and from the lens 57. By converting the reflected light bundle 73 into a convergent light bundle, the reflected light from the surface 65 is condensed on the end face 77.

  On the other hand, in the lens system 52, the lenses 56 and 58 are, for example, cylindrical convex lenses, and are provided so that each optical axis is along the reference axis 70.

  The lens 58 irradiates the sample 151 with light from the light source 4 through the surface 66 as a second light projecting unit.

  More specifically, the lens 56 is a light bundle that faces the end face 78 of the optical fiber 32 optically coupled with itself and that has the optical axis of the lens 56 as an axis out of the light bundle of light from the end face 78. The projected light beam 72 is received and converted from a divergent beam beam to a parallel beam beam. Therefore, the axis of the projection light beam 72 is along the reference axis 70.

  The lens 58 is provided between the lens 56 and the transmissive substrate 62, and is a surface facing the surface 66 with the light from the light source 4 by converting the projected light bundle 72 from the lens 56 into a convergent light bundle. Light is collected near the surface 82 of the sample 151 via the surface 66.

  The lens 58 in the lens system 52 receives the reflected light from the surface 66 of the transmissive substrate 62 and receives the reflected light from the sample 151 via the surface 66 as a second light receiving unit.

  More specifically, the surface 66 is an interface between the transmission substrate 62 and the air layer, and thus reflects light received from the lens 58. Further, the surface 82 of the sample 151 is an interface between the sample 151 and the air layer, and thus reflects light received from the lens 58 via the transmission substrate 62.

  The lens 58 receives a reflected light beam 76, which is a light beam having the optical axis of the lens 58 as an axis, out of the light beam reflected by the sample 151 through the surface 66, and generates a parallel light beam from the divergent light beam. Convert to a bunch. Therefore, the axis of the reflected light beam 76 is along the reference axis 70.

  Further, the lens 58 receives a reflected light beam 74 that is a light beam having the optical axis of the lens 58 as an axis out of the light beam reflected by the surface 66, and converts the divergent light beam into a parallel light beam. . Therefore, the axis of the reflected light bundle 74 is along the reference axis 70. In this example, since the distance between the surface 66 and the surface 82 is short compared to the distance between the lens 58 and the surface 82, the reflected ray bundle 74 is approximated as being converted into a parallel ray bundle by the lens 58. ing.

  The lens 56 condenses the reflected light from the sample 151 via the surface 66 on the end face 78 of the optical fiber 32 by converting the reflected light bundle 76 from the lens 58 into a convergent light bundle, and from the lens 58. By converting the reflected light beam 74 into a convergent light beam, the reflected light from the surface 66 is condensed on the end surface 78.

  For example, the optical system 5 guides the light received by the lens 57 and the light received by the lens 58 to the spectroscope 41 in the spectroscopic unit 3.

  More specifically, the optical fiber 31 in the optical system 5 transmits the reflected light received from the lens 55 to the fiber junction 35. The optical fiber 32 transmits the reflected light received from the lens 56 to the fiber junction 35.

  Referring again to FIG. 3, the fiber junction 35 mixes the reflected light received from the optical fibers 31 and 32 at the coupling unit 36, and outputs the mixed reflected light to the optical fiber 33.

  Referring again to FIG. 1, the optical fiber 33 transmits each reflected light mixed by the fiber junction 35 to the spectroscope 41 in the spectroscopic unit 3.

  For example, in the thickness measuring apparatus 101, the optical distance of the path of reflected light propagating from the sample 151 to the spectroscope 41 via the surface 65, the lens 57 and the optical system 5, and the surface 151 from the sample 151 to the surface 66, the lens 58 and the optical system. The optical distance of the path of the reflected light propagating to the spectroscope 41 via 5 is set to be the same.

  In other words, in the thickness measuring apparatus 101, the optical distance of the path of the reflected light propagating from the sample 151 to the spectroscope 41 via the surface 65, the lens 57 and the optical system 5, and the sample 151 to the surface 66, the lens 58 and optical. The optical distance of the path of reflected light propagating to the spectroscope 41 via the system 5 is substantially the same.

  More specifically, in the thickness measurement apparatus 101, when the distance between the surface 65 and the surface 81 and the distance between the surface 66 and the surface 82 are substantially the same, the size of the probes 1 and 2 is as follows. The lengths of the optical fibers 31 and 32 are set.

  That is, the time required for light to propagate from the surface 81 through the surface 65, the lenses 57 and 55 and the optical fiber 31 to the coupling portion 36 (see FIG. 3) in the fiber junction 35, and the light from the surface 82 to the surface 66, The sizes of the probes 1 and 2 and the lengths of the optical fibers 31 and 32 are set so that the time required for propagation to the coupling portion 36 in the fiber junction 35 through the lenses 58 and 56 and the optical fiber 32 is substantially the same. Is set.

  In this example, the distance between the surface 65 and the end face 77 of the optical fiber 31 and the distance between the surface 66 and the end face 78 of the optical fiber 32 are set to be substantially the same. The length from the end surface 77 to the coupling portion 36 in the fiber junction 35 and the length from the end surface 78 of the optical fiber 32 to the coupling portion 36 are set to be substantially the same.

  The spectroscopic unit 3 splits the reflected light received by the lens 57 and the reflected light received by the lens 58.

  More specifically, the spectroscope 41 in the spectroscopic unit 3 is provided with a diffraction grating and a one-dimensional image sensor, and each reflected light transmitted by the optical fiber 33 is diffracted by the diffraction grating and becomes a one-dimensional image sensor. Irradiated.

  The one-dimensional image sensor accumulates electric charges according to the intensity of each reflected light for each wavelength by photoelectrically converting each reflected light diffracted by the diffraction grating.

  The data generation unit 42 acquires a charge for each wavelength accumulated in a predetermined gate time in the one-dimensional image sensor, thereby generating a signal indicating the intensity for each wavelength, and the generated signal is, for example, an RS232C communication standard or Ethernet. According to the (registered trademark) communication standard, the data is output to the calculation unit 6.

  When receiving a signal from the data generation unit 42, the calculation unit 6 converts the intensity for each wavelength indicated by the received signal into a reflectance for each wavelength.

  More specifically, for example, the calculation unit 6 holds, as dark spectrum data, the intensity for each wavelength indicated by the signal received from the data generation unit 42 in a state where light does not enter the spectroscope 41.

  In addition, the calculation unit 6 performs, for example, for each wavelength indicated by the signal received from the data generation unit 42 in a state where a reference object such as an aluminum plate is provided between the transmission substrate 61 and the transmission substrate 62 instead of the sample 151. The intensity for each wavelength obtained by subtracting the intensity for each wavelength included in the dark spectrum data from the intensity is held as reference spectrum data.

  The calculation unit 6 calculates the wavelength for each wavelength included in the dark spectrum data with respect to the intensity for each wavelength indicated by the signal received from the data generation unit 42 when the sample 151 is provided between the transmission substrate 61 and the transmission substrate 62. After subtracting the respective intensities, the respective spectral intensities are divided by the intensities for each wavelength included in the reference spectrum data, thereby generating reflection spectrum data including the reflectance for each wavelength.

  FIG. 4 is a diagram showing an example of a power spectrum generated in the calculation unit in the thickness measuring apparatus according to the embodiment of the present invention. In FIG. 4, the vertical axis indicates the power spectrum intensity, and the horizontal axis indicates the thickness.

  Referring to FIG. 2 and FIG. 4, for example, based on the spectroscopic result of spectroscopic unit 3, arithmetic unit 6 determines d1 that is the distance between surface 65 and sample 151, and between surface 66 and sample 151. D2 which is the distance of is calculated.

  In more detail, the calculating part 6 calculates the power spectrum which shows the power spectrum intensity | strength for every spatial frequency by Fourier-transforming the produced | generated reflection spectrum data. And the calculating part 6 produces | generates the power spectrum shown in FIG. 4 by converting a spatial frequency into thickness.

  The computing unit 6 calculates the distance d1 from the position of the peak P1 based on the interference between the reflected light from the surface 81 and the reflected light from the surface 65. In addition, the calculation unit 6 calculates the distance d2 from the position of the peak P2 based on the interference of the reflected light from the surface 82 and the reflected light from the surface 66. In this example, the calculation unit 6 calculates the distances d1 and d2 as 168.3 micrometers and 625.4 micrometers, respectively.

  FIG. 5 is a diagram showing an example of a power spectrum generated in the calculation unit in the thickness measuring apparatus according to the embodiment of the present invention. In FIG. 5, the vertical axis indicates the power spectrum intensity, and the horizontal axis indicates the thickness.

  Referring to FIGS. 2 and 5, calculation unit 6 calculates the thickness of sample 151 by subtracting distances d1 and d2 from inter-surface distance da, which is the distance between surface 65 and surface 66, for example.

  For example, the inter-surface distance da is obtained by the following method. That is, in a state where the sample 151 is not provided between the transmissive substrate 61 and the transmissive substrate 62, light from the light source 4 is irradiated from the lens 57 to the surface 66 through the surface 65, and reflected light from the surface 65 is reflected on the lens. 57, the reflected light from the surface 66 is received by the lens 57 through the surface 65, the light from the light source 4 is irradiated from the lens 58 to the surface 65 through the surface 66, and the reflected light from the surface 66 is reflected. Light received by the lens 58 and reflected light from the surface 65 is received by the lens 58 through the surface 66.

  In such a state, the calculation unit 6 calculates the power spectrum intensity for each spatial frequency, that is, the power spectrum, by performing Fourier transform on the intensity for each wavelength indicated by the signal received from the data generation unit 42. And the calculating part 6 produces | generates the power spectrum shown in FIG. 5 by converting a spatial frequency into thickness.

  For example, in the state described above, the calculation unit 6 interferes with reflected light from the surface 65 to the lens 57, interference of reflected light from the surface 66 to the lens 57 via the surface 65, and reflected light from the surface 66 to the lens 58. And the inter-surface distance da is calculated from the position of the peak Pa based on the interference of reflected light from the surface 65 to the lens 58 via the surface 66. In this example, the calculation unit 6 calculates the inter-surface distance da as 2800.0 micrometers. Therefore, the calculation unit 6 calculates 2006.3 micrometers as the thickness of the sample 151 by calculating (2800.0-168.3-625.4).

  In the thickness measuring apparatus 101, the calculation unit 6 is configured to calculate the inter-surface distance da by the above-described method, but is not limited thereto. The calculation unit 6 may be configured to hold in advance the inter-surface distance da obtained by another method, for example, a mechanical measurement method. In this case, the calculation unit 6 calculates the thickness of the sample 151 using the inter-surface distance da that is held.

[Measuring method]
FIG. 6 is a flowchart defining an example of the procedure of a measurement method using the thickness measurement apparatus according to the embodiment of the present invention.

  With reference to FIG. 6, first, the thickness measurement apparatus 101 performs a spectral result by the spectroscopic unit 3 of the reflected light received by the lens 57 and the reflected light received by the lens 58 in a state where the sample 151 is not provided. To get. Specifically, the thickness measuring apparatus 101 acquires the power spectrum shown in FIG. 5 (step S102).

  Next, the thickness measuring apparatus 101 calculates the inter-surface distance da based on the acquired spectral result. Specifically, the thickness measuring apparatus 101 calculates the inter-surface distance da from the position of the peak Pa in the power spectrum shown in FIG. 5 (step S104).

  Next, the measurer places the sample 151 between the transmission substrate 61 and the transmission substrate 62 (step S106).

  Next, the thickness measuring apparatus 101 acquires the spectral result by the spectroscopic unit 3, specifically, the power spectrum shown in FIG. 4 in the state where the sample 151 is provided (step S108).

  Next, the thickness measuring apparatus 101 calculates the distances d1 and d2 based on the spectroscopic result by the spectroscopic unit 3 in the state where the sample 151 is provided. Specifically, thickness measuring apparatus 101 calculates distances d1 and d2 from the positions of peaks P1 and P2 in the power spectrum shown in FIG. 4 (step S110).

  Next, the thickness measuring apparatus 101 calculates the thickness of the sample 151 by subtracting the distances d1 and d2 from the inter-surface distance da (step S112).

  Note that the order of steps S102 to S104 and steps S106 to S110 is not limited to the above, and the order may be switched.

  Further, although the thickness measuring apparatus 101 calculates the inter-surface distance da in steps S102 and S104, the present invention is not limited to this. The thickness measuring apparatus 101 does not have to calculate the inter-surface distance da when the inter-surface distance da is previously held as described above.

  Further, the thickness measurement apparatus 101, in the case where light is irradiated from both of the lenses 57 and 58 in the above-described step S102, reflects the reflected light received by the lens 57 and the reflected light received by the lens 58. However, the present invention is not limited to this. In the above step S102, the thickness measuring apparatus 101 may acquire the spectral result of the reflected light received by the corresponding lens when light is emitted from either the lens 57 or the lens 58.

  In the thickness measuring device according to the embodiment of the present invention, the spectroscopic unit 3 is configured to include one spectroscope 41. However, the present invention is not limited to this. The spectroscopic unit 3 may include two spectroscopes 41. In this case, the two spectroscopes 41 separate the reflected light received by the lens 57 and the reflected light received by the lens 58, respectively. The calculation unit 6 calculates the distances d1 and d2 based on the spectral results of the two spectroscopes 41.

  Moreover, although the thickness measuring apparatus which concerns on embodiment of this invention was set as the structure provided with the one light source 4, it is not limited to this. The thickness measuring apparatus 101 may be configured to include two light sources 4. In this case, the lens 57 irradiates the sample 151 with light from one light source 4 through the surface 65. The lens 58 irradiates the sample 151 with light from the other light source 4 via the surface 66.

  In the thickness measuring device according to the embodiment of the present invention, the first light projecting unit and the first light receiving unit are integrated, but the present invention is not limited to this. In the thickness measuring apparatus 101, the first light projecting unit and the first light receiving unit may be provided separately.

  Specifically, the thickness measuring apparatus 101 may be configured to include a lens 57 that functions as a first light projecting unit and another lens that functions as a first light receiving unit. It may be configured to include a lens 57 that functions as a unit and another lens that functions as a first light projecting unit.

  That is, the axis of the light projection beam bundle 71 of light irradiated from the lens 57 to the sample 151 through the surface 65 and the axis of the light projection beam bundle 72 of light irradiated from the lens 58 through the surface 66 to the sample 151. The axis of the reflected beam bundle 73 of the reflected light from the surface 65 received by the lens 57 and the axis of the reflected beam bundle 75 of the reflected light from the sample 151, and the reflected beam of the reflected light from the surface 66 received by the lens 58. The axis of the bundle 74 and the axis of the reflected light bundle 76 of the reflected light from the sample 151 may not be along each other.

  Further, the thickness measuring apparatus 101 is provided with a half mirror between the transmission substrate 61 and the lens 57 shown in FIG. 1, so that the lens 57 functioning as a first light projecting unit and the reflected light reflected by the half mirror. The first light projecting unit that irradiates the sample 151 with the light from the light source 4 through the half mirror and the surface 65 may be used. It is also possible to have a configuration including another lens that functions as a lens 57 and a lens 57 that functions as a first light receiving unit. In these configurations, the axes of the projection beam bundle 71 and the reflected beam bundles 73 and 75 can be aligned with each other on the surface 65 and the surface 81.

  Similarly, in the thickness measuring apparatus according to the embodiment of the present invention, the second light projecting unit and the second light receiving unit are integrated, but the present invention is not limited to this. In the thickness measuring apparatus 101, the second light projecting unit and the second light receiving unit may be provided separately.

  Specifically, the thickness measuring apparatus 101 may be configured to include a lens 58 that functions as a second light projecting unit and another lens that functions as a second light receiving unit. A configuration may be provided that includes a lens 58 that functions as a unit and another lens that functions as a second light projecting unit.

  Further, the thickness measuring apparatus 101 is provided with a half mirror between the transmission substrate 62 and the lens 58 shown in FIG. 1, so that the lens 58 functioning as the second light projecting unit and the reflected light reflected by the half mirror are provided. And a second light projecting unit that irradiates the sample 151 with light from the light source 4 via the half mirror and the surface 66. The other lens that functions as the lens and the lens 58 that functions as the second light receiving unit may be included. In these configurations, the axes of the projection beam bundle 72 and the reflected beam bundles 74 and 76 can be aligned with each other at the surface 66 and the surface 82.

  In the thickness measuring apparatus according to the embodiment of the present invention, the surface 65 that is the surface facing the sample 151 of the transmission substrate 61 is used as the first reference surface. However, the present invention is not limited to this. Absent. The thickness measuring apparatus 101 may have a configuration in which a surface 67 that is a surface opposite to the sample 151 of the transmission substrate 61 is used as the first reference surface.

  Moreover, in the thickness measuring apparatus according to the embodiment of the present invention, the surface 66 that is the surface facing the sample 151 of the transmission substrate 62 is used as the second reference surface. However, the present invention is not limited to this. Absent. The thickness measuring apparatus 101 may have a configuration in which the surface 68 that is the surface opposite to the sample 151 of the transmission substrate 62 is used as the second reference surface.

  Moreover, although the thickness measuring apparatus which concerns on embodiment of this invention was set as the structure provided with the light source 4, the optical system 5, and the calculating part 6, it is not limited to this. A configuration in which at least one of the light source 4, the optical system 5, and the calculation unit 6 is provided outside the thickness measuring device 101 may be employed.

  In the thickness measurement device according to the embodiment of the present invention, the spectroscopic unit 3 includes the data generation unit 42, but the configuration is not limited thereto. The data generation unit 42 may be provided outside the thickness measuring apparatus 101.

  By the way, when measuring the thickness of the sample using the techniques described in Patent Documents 1 to 3, for example, the thickness of the sample is determined from the measurement result of the distance to the grounded sample and the measurement result of the distance to the ground plane. A method of measuring is conceivable.

  However, when the surface of the sample is uneven, or the sample is distorted or warped, a gap is generated between the surface of the sample on the ground surface side and the ground surface. In such a case, it may be difficult to accurately measure the thickness of the sample.

  FIG. 7 is a diagram illustrating a comparative example of probes. Referring to FIG. 7, for example, when the thickness of the sample 93 grounded to the stage 92 is measured using the light projected and received by the probe 91, the surface 94 as a reference surface and the contact at the stage 92 are measured. The distance dw obtained by subtracting the distance ds between the surface 94 and the sample 93 from the distance dg between the ground is measured as the thickness of the sample 93. As shown in FIG. 7, since the surface of the sample 93 has irregularities, dw is calculated as the thickness of the sample 93 even though the correct thickness of the sample 93 is d.

  On the other hand, in the thickness measuring apparatus according to the embodiment of the present invention, the transmission substrate 61 has a surface 65. The transmissive substrate 62 is provided to face the transmissive substrate 61 and has a surface 66. The lens 57 irradiates the sample 151 located between the transmissive substrate 61 and the transmissive substrate 62 through the surface 65 with the light from the light source 4. The lens 57 receives the reflected light from the surface 65 and receives the reflected light from the sample 151 via the surface 65. The lens 58 irradiates the sample 151 with light from the light source 4 via the surface 66. The lens 58 receives reflected light from the surface 66 and receives reflected light from the sample 151 through the surface 66. The spectroscopic unit 3 splits the reflected light received by the lens 57 and the reflected light received by the lens 58.

  In this way, light is irradiated to both sides of the sample 151 through the surfaces 65 and 66, and the reflected light from the surfaces 81 and 82 on both sides of the sample 151 is caused to interfere with the reflected light from the surfaces 65 and 66, respectively. Even if the surfaces 81 and 82 of the sample 151 are uneven or the sample 151 is distorted or warped, the surfaces 81 and 82 on both sides of the sample 151 and the surfaces 65 and 66 are based on the spectroscopic result. The distances d1 and d2 between the two can be calculated. For example, the thickness of the sample 151 can be accurately calculated from the calculated distances d1 and d2 and the inter-surface distance da between the surfaces 65 and 66. Therefore, the thickness of the sample can be accurately measured.

  Further, in the thickness measuring apparatus according to the embodiment of the present invention, the spectroscopic unit 3 includes one spectroscope 41. Then, the optical system 5 guides the light received by the lens 57 and the light received by the lens 58 to the spectroscope 41.

  With such a configuration using the optical system 5, the number of expensive spectrometers 41 can be minimized, so that the manufacturing cost of the thickness measuring apparatus 101 can be reduced.

  Further, in the thickness measuring apparatus according to the embodiment of the present invention, the axis of the projection beam 71 of the light irradiated from the lens 57 through the surface 65 to the sample 151 and the sample 151 from the lens 58 through the surface 66 are used. The axis of the projected light bundle 72 of the light irradiated to the lens, the axis of the reflected light bundle 73 of the reflected light from the surface 65 received by the lens 57, the axis of the reflected light bundle 75 of the reflected light from the sample 151, and the lens The axis of the reflected beam bundle 74 of the reflected light from the surface 66 received by the 58 and the axis of the reflected beam bundle 76 of the reflected light from the sample 151 are along each other.

  With such a configuration, even when the surfaces 65 and 66 are arranged non-parallel, or when the sample 151 is provided non-parallel to the surfaces 65 and 66, the thickness of the sample is accurately measured. be able to.

  For example, as shown in FIG. 2, when the sample 151 moves along the reference axis 70 in the direction approaching the surface 65 at a speed v, the following problem may occur. That is, the difference between the time T1 required for the reflected light from the surface 81 to reach the spectroscope 41 and the time T2 required for the reflected light from the surface 82 to reach the spectroscope 41 is (T1-T2). If ΔT, the sample 151 approaches the surface 65 by a distance of v × ΔT during the time ΔT. Accordingly, the calculation unit 6 calculates the distance d2 based on the reflected light from the surface 82 and the reflected light from the surface 66, while calculating the distance (d1 + v × based on the reflected light from the surface 81 and the reflected light from the surface 65. ΔT) is calculated. In other words, it becomes difficult for the thickness measuring apparatus 101 to accurately calculate the thickness of the sample 151.

  Further, for example, a first spectroscope that splits the reflected light received by the lens 57 and a second spectroscope that splits the reflected light received by the lens 58 are prepared, and the first spectroscope reflects the reflected light. A method of accurately calculating the thickness of the sample 151 by delaying the timing of separating the light by ΔT with respect to the timing at which the second spectrometer separates the reflected light is conceivable. However, it is not preferable because the control of the spectroscopic timing of each spectroscope becomes complicated.

  On the other hand, in the thickness measuring apparatus according to the embodiment of the present invention, the spectroscopic unit 3 includes one spectroscope 41. The optical system 5 guides the light received by the lens 57 and the light received by the lens 58 to the spectroscope 41. Then, the optical distance of the path of the reflected light propagating from the sample 151 to the spectroscope 41 via the surface 65, the lens 57 and the optical system 5, and the spectral from the sample 151 via the surface 66, the lens 58 and the optical system 5. The optical distance of the path of the reflected light propagating to the device 41 is set to be the same.

  With such a configuration, the time required for the light reflected on the surfaces 81 and 82 on both sides of the sample 151 to reach the spectroscope 41 can be made substantially the same. The spectroscope 41 can split the reflected light reflected by. Thereby, even when the sample 151 is moving, the thickness of the sample 151 can be accurately measured with a simple configuration.

  Further, in the thickness measuring apparatus according to the embodiment of the present invention, the calculation unit 6 is based on the spectroscopic result obtained by the spectroscopic unit 3 and d1 which is the distance between the surface 65 and the sample 151, and the surface 66 and the sample 151. D2 which is the distance between the two is calculated. Then, the calculation unit 6 calculates the thickness of the sample 151 by subtracting the distances d1 and d2 from the inter-surface distance da between the surface 65 and the surface 66.

  As described above, the thickness of the sample 151 can be calculated even if the sample 151 is an opaque substance by the configuration in which the thickness of the sample 151 is calculated from each distance that is a measurement result of the space outside the sample 151. In addition, the thickness of the sample 151 can be easily calculated without recognizing a physical property value such as the refractive index of the sample 151.

  Moreover, the thickness measuring method according to the embodiment of the present invention is a thickness measuring method using the thickness measuring apparatus 101, and based on the spectral result by the spectroscopic unit 3, the distance d1 between the surface 65 and the sample 151, And calculating the distance d2 between the surface 66 and the sample 151, and calculating the thickness of the sample 151 by subtracting the distances d1 and d2 from the inter-surface distance da between the surface 65 and the surface 66. Including.

  In this way, light is irradiated to both sides of the sample 151 through the surfaces 65 and 66, and the reflected light from the surfaces 81 and 82 on both sides of the sample 151 is caused to interfere with the reflected light from the surfaces 65 and 66, respectively. Even if the surfaces 81 and 82 of the sample 151 are uneven or the sample 151 is distorted or warped, the surfaces 81 and 82 on both sides of the sample 151 and the surfaces 65 and 66 are based on the spectroscopic result. The distances d1 and d2 between the two can be calculated. The thickness of the sample 151 can be accurately calculated from the calculated distances d1 and d2 and the inter-surface distance da between the surfaces 65 and 66. Therefore, the thickness of the sample can be accurately measured. In addition, by calculating the thickness of the sample 151 from each distance that is a measurement result of the space outside the sample 151, the thickness of the sample 151 can be calculated even if the sample 151 is an opaque substance. In addition, the thickness of the sample 151 can be easily calculated without recognizing a physical property value such as the refractive index of the sample 151.

  Further, in the thickness measuring apparatus according to the embodiment of the present invention, in a state where the sample 151 is not provided, the light from the light source 4 is irradiated from the lens 57 to the surface 66 through the surface 65 and reflected from the surface 65. Light is received by the lens 57, and reflected light from the surface 66 is received by the lens 57 through the surface 65. In the thickness measurement method according to the embodiment of the present invention, the inter-surface distance da is further calculated based on the spectral result by the spectroscopic unit 3 of the reflected light received by the lens 57 in the state where the sample 151 is not provided. Including the steps of:

  With such a configuration, the inter-surface distance da can be calculated using the same method as the calculation method of the distances d1 and d2. Therefore, the inter-surface distance da can be calculated with high calculation accuracy comparable to the calculation accuracy of the distances d1 and d2. Can be calculated. Thereby, for example, the thickness of the sample 151 can be calculated more accurately than in the case where the inter-surface distance da is calculated using another method with inaccurate accuracy.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1, 2 Probe 3 Spectrometer 4 Light source 5 Optical system 6 Arithmetic unit 31, 32, 33, 34 Optical fiber 35 Fiber junction 36 Coupling part 41 Spectroscope 42 Data generation part 51, 52 Lens system 55, 56, 57, 58 Lens 61, 62 Transmission substrate 65, 66, 67, 68 Surface 70 Reference axis 71, 72 Emitted beam bundle 73, 74, 75, 76 Reflected beam bundle 77, 78 End surface 81, 82 Surface 91 Probe 92 Stage 93 Sample 94 Surface 101 Thickness measuring device 151 Sample

Claims (7)

A first transmissive member having a first reference surface;
A second transmission member provided opposite to the first transmission member and having a second reference surface;
A first light projecting unit for irradiating a sample located between the first transmission member and the second transmission member through the first reference surface with light from a light source;
A first light receiving unit for receiving reflected light from the first reference surface and receiving reflected light from the sample through the first reference surface;
A second light projecting unit for irradiating the sample with light from a light source via the second reference surface;
A second light receiving unit for receiving reflected light from the second reference surface and receiving reflected light from the sample through the second reference surface;
A thickness measuring device comprising: a reflected light received by the first light receiving part; and a spectroscopic part for dispersing the reflected light received by the second light receiving part. The spectroscopic unit includes one spectroscope,
The thickness measuring device further includes:
The thickness measuring apparatus according to claim 1, further comprising an optical system for guiding the light received by the first light receiving unit and the light received by the second light receiving unit to the spectrometer.   An axis of a light bundle of light irradiated from the first light projecting unit through the first reference surface to the sample, and the sample from the second light projecting unit through the second reference surface An axis of a light bundle of light irradiated onto the first light receiving portion, an axis of a light bundle of reflected light from the first reference surface received by the first light receiving unit, and an axis of a light bundle of reflected light from the sample; The axis of the beam bundle of reflected light from the second reference surface received by the second light receiving unit and the axis of the beam bundle of reflected light from the sample are along each other. The thickness measuring device described in 1. The spectroscopic unit includes one spectroscope,
The thickness measuring device further includes:
An optical system for guiding the light received by the first light receiving unit and the light received by the second light receiving unit to the spectrometer;
The optical distance of the path of reflected light propagating from the sample to the spectroscope via the first reference surface, the first light receiving unit and the optical system, and the second reference surface from the sample, The optical distance of the path | route of the reflected light which propagates through the 2nd light-receiving part and the said optical system to the said spectrometer is set so that it may become the same. The thickness measuring device according to item. The thickness measuring device further includes:
Based on the spectroscopic result of the spectroscopic unit, a first distance that is a distance between the first reference surface and the sample, and a second distance that is a distance between the second reference surface and the sample. An arithmetic unit for calculating
The calculation unit calculates the thickness of the sample by subtracting the first distance and the second distance from a distance between the first reference surface and the second reference surface. Item 5. The thickness measuring device according to any one of items 4 to 5. A first transmissive member having a first reference surface;
A second transmission member provided opposite to the first transmission member and having a second reference surface;
A first light projecting unit for irradiating light from a light source to the sample located between the first transmission member and the second transmission member via the first reference surface;
A first light receiving unit for receiving reflected light from the first reference surface and receiving reflected light from the sample through the first reference surface;
A second light projecting unit for irradiating the sample with light from a light source via the second reference surface;
A second light receiving unit for receiving reflected light from the second reference surface and receiving reflected light from the sample through the second reference surface;
A thickness measuring method using a thickness measuring device comprising: a reflected light received by the first light receiving unit; and a spectroscopic unit that splits the reflected light received by the second light receiving unit,
Based on the spectroscopic result of the spectroscopic unit, a first distance that is a distance between the first reference surface and the sample, and a second distance that is a distance between the second reference surface and the sample. Calculating steps,
Calculating a thickness of the sample by subtracting the first distance and the second distance from an inter-surface distance that is a distance between the first reference surface and the second reference surface. Measuring method. In a state where the sample is not provided, light from a light source is irradiated from the first light projecting unit to the second reference surface via the first reference surface, and from the first reference surface. Reflected light is received by the first light receiving unit, and reflected light from the second reference surface is received by the first light receiving unit through the first reference surface,
The thickness measurement method further includes:
The thickness measurement according to claim 6, comprising a step of calculating the inter-surface distance based on a spectroscopic result by the spectroscopic unit of reflected light received by the first light receiving unit in a state where the sample is not provided. Method.

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