Foreign body inspection system and foreign body inspection method

Abstract

To flexibly inspect presence / absence of a foreign matter inside an inspection object in response to a situation.SOLUTION: In a foreign matter inspection system 1, an illumination device 10 irradiates an inspection object 3 with visible light and infrared light. A photographing device 30 acquires a visible image obtained by photographing the inspection object 3 with the visible light radiated from the illumination device 10 and an infrared image obtained by photographing the inspection object 3 with the infrared light radiated from the illumination device 10. An image processing device 50 inspects presence / absence of a foreign matter inside the inspection object 3 based on the visible image and infrared image acquired by the photographing device 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a foreign matter inspection system. Mu and and a foreign body inspection method. [Background technology]

[0002] There are known techniques for inspecting the presence or absence of foreign matter inside an object to be inspected. For example, Patent Document 1 discloses a void inspection device that observes the inside of a laminate by irradiating the laminate with infrared wavelength illumination light and inspects for voids hidden at the interface of the laminate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-168280 Summary of the Invention [Problem to be solved by the invention]

[0004] By using infrared light as described above, it is possible to inspect the presence or absence of foreign matter inside an inspection object even when inspection using visible light is difficult. On the other hand, inspection using infrared light generally has difficulty in inspecting the presence or absence of foreign matter with the same high accuracy as inspection using visible light. Also, depending on the material of the inspection object, there are cases where using visible light is more appropriate. Under these circumstances, there is a demand for flexible inspection of the presence or absence of foreign matter inside an inspection object according to the situation.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a foreign matter inspection system etc. that can flexibly inspect the presence or absence of foreign matter inside an inspection object according to the situation. [Means for solving the problem]

[0006] In order to achieve the above object, a foreign matter inspection system according to a first aspect of the present invention comprises: an illumination device that irradiates the inspection object with visible light and infrared light; an imaging device that acquires a visible image of the inspection object captured by the visible light irradiated by the lighting device and an infrared image of the inspection object captured by the infrared light irradiated by the lighting device; an image processing device that inspects the presence or absence of foreign matter inside the inspection object based on the visible image and the infrared image acquired by the imaging device; 、 The image processing device includes: determining whether or not a first foreign matter that satisfies a predetermined condition exists inside the inspection object based on the infrared image obtained by capturing the inspection object using the infrared light before the polishing process is performed; If it is determined that there is no first foreign matter that satisfies the predetermined conditions inside the inspection object, the presence or absence of a second foreign matter inside the inspection object is determined based on the visible image of the inspection object captured using visible light after the polishing process has been performed.

[0008] In order to achieve the above object, the present invention 2 The foreign matter inspection method according to the above aspect is a first acquisition step of irradiating an inspection object with infrared light to acquire an infrared image of the inspection object captured with the infrared light; a first determination step of determining whether or not a first foreign matter that satisfies a predetermined condition exists inside the inspection object based on the infrared image acquired in the first acquisition step; a polishing step of polishing the inspection object when it is determined in the first determination step that the first foreign matter satisfying a predetermined condition is not present inside the inspection object; a second acquisition step of irradiating the inspection object polished in the polishing step with visible light to acquire a visible image of the inspection object photographed with the visible light; and a second determination step of determining the presence or absence of a second foreign matter inside the inspection object based on the visible image acquired in the second acquisition step. [Effects of the Invention]

[0009] According to the present invention, the presence or absence of foreign matter inside an inspection object can be flexibly inspected according to the situation. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing the overall configuration of a foreign matter inspection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of an inspection target according to an embodiment. [Figure 3] 1A is a diagram showing the configuration of an illumination device of a foreign substance inspection system according to an embodiment, FIG. 1B is a diagram showing a case where the illumination device shown in FIG. 1A irradiates infrared light, and FIG. 1C is a diagram showing a case where the illumination device shown in FIG. 1A irradiates visible light. [Figure 4] 1A and 1B are diagrams illustrating how infrared light is irradiated onto an object to be inspected in an embodiment. [Figure 5] 1A and 1B are diagrams illustrating a state in which visible light is irradiated onto an inspection object in an embodiment. [Figure 6] 1 is a diagram showing an example of an infrared image of an inspection target captured by an imaging device of a foreign substance inspection system according to an embodiment; [Figure 7] 1A and 1B are diagrams showing examples of visible images of an inspection target captured by an imaging device of a foreign substance inspection system according to an embodiment. [Figure 8] 10A and 10B are diagrams illustrating an example of a focus position shift in an imaging device of the foreign substance inspection system according to the embodiment. [Figure 9] FIG. 2 is a block diagram showing the configuration of an image processing device of the foreign substance inspection system according to the embodiment. [Figure 10] 10 is a flowchart showing the flow of a foreign substance inspection process executed by the foreign substance inspection system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0012] (Embodiment 1) 1 shows the overall configuration of a foreign matter inspection system 1 according to an embodiment of the present invention. The foreign matter inspection system 1 is a device that inspects an inspection object 3 for the presence or absence of foreign matter.

[0013] <Test subject 3> The inspection object 3 is an object that is the target of foreign substance inspection by the foreign substance inspection system 1. As shown in FIG. 2, the inspection object 3 is a laminate having a first layer 3a and a second layer 3b. The first layer 3a is made of a first material, and the second layer 3b is made of a second material that is different from the first material. In this way, the inspection object 3 is a plate-like object in which two different materials are bonded together.

[0014] More specifically, the test object 3 is a SAW (Surface Acoustic Wave) filter. Here, a SAW filter is an element that is mainly used in communication devices such as mobile phones and smartphones, and extracts electrical signals in a specific frequency band.

[0015] In the SAW filter, the first layer 3a is a silicon (Si) layer, i.e., a layer formed using silicon as a material. On the other hand, the second layer 3b is a lithium tantalate (LiTaO3, hereinafter referred to as "LT") layer, i.e., a layer formed using LT as a material. The SAW filter is produced by bonding a silicon wafer and an LT wafer together using room temperature bonding.

[0016] The foreign matter inspection system 1 inspects the inspection object 3 for the presence or absence of foreign matter X1. In other words, the foreign matter inspection system 1 inspects the inspection object 3 for the presence or absence of voids between the first layer 3a and the second layer 3b of the inspection object 3 as the foreign matter X1. Here, a void is a cavity that occurs inside the inspection object 3. Voids tend to occur as unbonded areas between two wafers when the two wafers are bonded together. The occurrence of voids affects the performance of the SAW filter. The foreign matter inspection system 1 identifies areas that can be used as a SAW filter by inspecting the presence or absence of voids inside the SAW filter.

[0017] As shown in Figure 2, the inspection object 3 contains foreign particles X2 and X3 other than voids. Specifically, foreign particle X2 is a surface foreign particle, such as dust or dirt adhering to the surface of the inspection object 3. Such foreign particle X2 can be removed by cleaning before shipping. Furthermore, foreign particle X2 is imaged as a black defect in an image, so it can be distinguished using image processing. Furthermore, foreign particle X3 is a dent or the like that is created in the wafer during room-temperature bonding by a foreign particle transferred from the electrostatic chuck to the wafer. Such foreign particle X3 is removed by the CMP process described below, but is necessary for understanding the environment of the room-temperature bonding apparatus. On the other hand, foreign particle X1, which is a void, remains as a defect in the final product. Foreign particle X3 and foreign particle X1 are imaged as defects with different characteristics in an image, so they can be classified using image processing.

[0018] Returning to FIG. 1, the foreign substance inspection system 1 includes an illumination device 10, an imaging device 30, and an image processing device 50.

[0019] <Lighting device 10> The lighting device 10 is a unit that irradiates the inspection object 3 with visible light and infrared light. Specifically, the lighting device 10 irradiates electromagnetic waves with wavelengths of, for example, 450 to 700 nm as visible light. The lighting device 10 also irradiates electromagnetic waves with wavelengths of, for example, 1100 to 1200 nm (near-infrared light and short-wave infrared light) as infrared light. Hereinafter, when there is no need to distinguish between visible light and infrared light, they will be collectively referred to as "light."

[0020] As shown in Fig. 1, the illumination device 10 is disposed above the inspection object 3 and irradiates the inspection object 3 with light (visible light and infrared light) from above. More specifically, the inspection object 3 is transported in a predetermined direction along a predetermined transport path by a transport unit (not shown). In the example of Fig. 1, the inspection object 3 is transported in the +Y direction.

[0021] Illumination device 10 irradiates light (visible light and infrared light) from an oblique direction onto the surface of inspection object 3, which is transported in a predetermined direction. Specifically, illumination device 10 irradiates light onto inspection object 3 from a direction inclined by about 30° (e.g., 10 to 45°) with respect to the Z direction, which is the perpendicular direction to the surface of inspection object 3 along which inspection object 3 is transported. In other words, foreign substance inspection system 1 does not employ coaxial epi-illumination, but irradiates light from illumination device 10 onto inspection object 3 under illumination conditions of specular reflection.

[0022] The reason for adopting the illumination condition of specular reflection in this way is that in the case of coaxial epi-illumination, a beam splitter must be installed in the optical system, which has the following disadvantages (1) to (4).By adopting the illumination condition of specular reflection, the illumination device 10 can avoid these disadvantages of coaxial epi-illumination. (1) There is a risk of uneven brightness due to the beam splitter. (2) Since the incident light and the reflected light each pass through a beam splitter, the amount of light is attenuated by at least one-fourth, impairing high-speed performance. (3) When the beam splitter is constantly exposed to light, heat is generated, which affects the optical equipment (work distance). (4) Lens selection is difficult.

[0023] More specifically, as shown in FIG. 3(a), the lighting device 10 includes an infrared light source 11, a visible light source 12, a transmission member 13, an infrared light transmission filter 14, a visible light transmission filter 15, and a switching unit 16.

[0024] The infrared light source 11 is provided on one end side (the +X side in FIG. 3(a)) of the transmission member 13 and emits infrared light with a wavelength of 1100 to 1200 nm. The visible light source 12 is provided on the other end side (the -X side in FIG. 3(a)) of the transmission member 13 and emits visible light with a wavelength of 450 to 700 nm. Specifically, the infrared light source 11 and the visible light source 12 are LEDs (Light Emitting Diodes) that emit light of the corresponding wavelengths.

[0025] The transmission member 13 is, for example, a quartz rod. The transmission member 13 transmits (guides) the infrared light emitted from the infrared light source 11 and the visible light emitted from the visible light source 12 inside the transmission member 13, and emits the infrared light and the visible light from its side surface. The transmission member 13 has a rod-like shape, and its longitudinal direction corresponds to the ±X direction, i.e., a direction perpendicular to the transport direction in which the inspection object 3 is transported. The transmission member 13 is supported by a support member (not shown). The support member is, for example, aluminum casing. A cover glass or a cylindrical lens is attached to the support member.

[0026] The infrared light and visible light incident on the transmission member 13 are transmitted inside the member in the longitudinal direction. The transmission member 13 is provided with a reflector 13a on the surface opposite to the surface (irradiation surface) from which the infrared light and visible light are emitted, which reflects the infrared light and visible light transmitted inside the transmission member 13. The reflector 13a is an appropriate substance (e.g., white paint) that has the property of reflecting infrared light and visible light. The reflector 13a is applied to the surface of the transmission member 13 opposite to the irradiation surface, and reflects the infrared light and visible light transmitted inside the transmission member 13. Due to the action of such reflector 13a, the light transmitted inside the transmission member 13 is emitted from the side surface of the transmission member 13 in a direction perpendicular to the longitudinal direction as irradiation light that is close to parallel rays with high directionality due to a lens effect. In this way, the lighting device 10 can irradiate infrared light and visible light from the rod-shaped transmission member 13, thereby irradiating the infrared light and visible light onto a linear area on the inspection object 3 while suppressing local brightness unevenness and wavelength unevenness in the ±X directions.

[0027] The infrared light transmission filter 14 is provided at one end of the transmission member 13, and transmits infrared light emitted from the infrared light source 11 and reflects visible light emitted from the visible light source 12. The visible light transmission filter 15 is provided at the other end of the transmission member 13, and transmits visible light emitted from the visible light source 12 and reflects infrared light emitted from the infrared light source 11. The infrared light transmission filter 14 and the visible light transmission filter 15 are, for example, vapor-deposited filters having wavelength selectivity.

[0028] The switching unit 16 switches the infrared light source 11 on and off, and the visible light source 12 on and off. The switching unit 16 is, for example, a switch controlled by a user. The switching unit 16 is connected to the infrared light source 11 and the visible light source 12 via signal lines, and switches, under the control of the user, between a first state in which the infrared light source 11 emits infrared light and the visible light source 12 does not emit visible light, and a second state in which the infrared light source 11 does not emit infrared light and the visible light source 12 emits visible light.

[0029] First, when irradiating the inspection object 3 with infrared light, the lighting device 10 turns on the infrared light source 11 and turns off the visible light source 12, as shown in FIG. 3(b). In this case, the infrared light emitted from the infrared light source 11 passes through the infrared light transmission filter 14 and enters the transmission member 13 from one end of the transmission member 13. Then, as shown by the arrow in FIG. 3(b), the infrared light that has entered the transmission member 13 passes through the inside of the transmission member 13 and is emitted from the side of the transmission member 13. At this time, when the infrared light reaches the other end of the transmission member 13, it is totally reflected by the visible light transmission filter 15.

[0030] Second, when irradiating the inspection object 3 with visible light, the lighting device 10 turns on the visible light source 12 and turns off the infrared light source 11, as shown in FIG. 3(c). In this case, the visible light emitted from the visible light source 12 passes through the visible light transmission filter 15 and enters the transmission member 13 from the other end of the transmission member 13. Then, the visible light that has entered the transmission member 13 passes through the inside of the transmission member 13 and is emitted from the side of the transmission member 13, as shown by the arrow in FIG. 3(c). At this time, when the visible light reaches one end of the transmission member 13, it is totally reflected by the infrared light transmission filter 14.

[0031] By providing the infrared light transmitting filter 14 and the visible light transmitting filter 15 in this manner, the lighting device 10 can prevent infrared light and visible light from escaping from the end of the transmission member 13. Therefore, the infrared light and visible light can be efficiently emitted from the side surface of the transmission member 13.

[0032] 3(a) to 3(c), the infrared light source 11 and the visible light source 12 are arranged at both ends of the transmission member 13, but the infrared light source 11 and the visible light source 12 may be arranged at other locations. When the infrared light source 11 and the visible light source 12 are arranged at locations other than both ends of the transmission member 13, for example, an optical fiber, an external optical system, or the like may be used to guide the infrared light emitted from the infrared light source 11 to one end of the transmission member 13 and the visible light emitted from the visible light source 12 to the other end of the transmission member 13. Alternatively, an optical system that efficiently guides the infrared light emitted from the infrared light source 11 and the visible light emitted from the visible light source 12 to the transmission member 13 may be used.

[0033] The foreign substance inspection system 1 uses such an illumination device 10 to irradiate the inspection object 3 with infrared light and visible light to inspect for the presence or absence of foreign substance X1. The illumination device 10 is configured to allow infrared light and visible light to be incident from both ends of the transmission member 13, so that a single illumination device 10 can easily switch between irradiating infrared light and irradiating visible light. Furthermore, the illumination device 10 can irradiate infrared light and visible light from the same position while suppressing unevenness in brightness and wavelength.

[0034] As described above, the first layer 3a of the inspection object 3 is a silicon (Si) layer. Silicon has the property of not transmitting visible light with wavelengths shorter than 900 nm. Therefore, it is difficult to inspect the inside of the inspection object 3 even if visible light is irradiated from the side of the first layer 3a. On the other hand, the transmittance of silicon gradually increases from wavelengths of 900 nm or more. Furthermore, infrared light with a wavelength of approximately 1000 nm or more can provide a sufficient amount of light to observe the inside of the silicon layer.

[0035] 4, the illumination device 10 irradiates the inspection object 3 with infrared light from the side of the first layer 3a. In this case, the inspection object 3 is transported by the transport unit with the first layer 3a facing upward, that is, toward the illumination device 10 and the imaging device 30.

[0036] More specifically, before chemical-mechanical polishing (CMP) is performed on the second layer 3b, the illumination device 10 turns on the infrared light source 11 and turns off the visible light source 12 using the switching unit 16, thereby irradiating the inspection object 3 with infrared light from the side of the first layer 3a. Here, CMP refers to a process of planarizing the surface of a semiconductor wafer by polishing. CMP is performed by a dedicated CMP device that polishes the wafer surface chemically using chemicals containing abrasives and mechanically using a grindstone. CMP is an example of a polishing process.

[0037] The second layer 3b, which is an LT layer, is not thinned or mirror-finished before being polished by CMP. Therefore, when inspecting the second layer 3b before being polished by CMP, the accuracy of foreign matter inspection is limited to about φ100 μm due to the influence of light scattering on the surface, making high-precision inspection difficult. While there are also inspection methods that use ultrasound instead of visible light, these methods require about half a day to measure the entire surface of a 4-inch wafer, making in-line implementation difficult.

[0038] On the other hand, if the second layer 3b has been subjected to CMP, inspection using visible light allows for both high-speed inspection and inspection with an accuracy of approximately φ5 μm, which is equivalent to that achieved using ultrasound. However, if CMP is performed while voids or other foreign matter remain inside the inspection target 3, numerous particles are generated in the CMP equipment, leading to situations where equipment maintenance is required, such as cracking of the substrate. In such cases, equipment maintenance (restoration) work to recreate a vacuum, for example, can take 2 to 3 hours.

[0039] Under these circumstances, before the second layer 3b is polished by CMP, the illumination device 10 irradiates infrared light from the side of the first layer 3a, which is a silicon layer, without irradiating visible light or infrared light from the side of the second layer 3b, which is a LT layer, as shown in Figure 4. In this way, the foreign matter inspection system 1 performs foreign matter inspection with the aim of improving yield. By using infrared light, it is possible to inspect the presence or absence of foreign matter inside the inspection object 3 with an accuracy of about φ10 to 20 μm.

[0040] On the other hand, when the second layer 3b is polished by CMP, the second layer 3b becomes thinner and light scattering on the surface is suppressed. This makes it possible to inspect the inside of the inspection object 3 using visible light. Inspection using visible light can achieve higher accuracy than infrared light, so it is necessary to guarantee the performance of the SAW filter as a final product during shipping inspection.

[0041] 5, after CMP is performed on the second layer 3b, the illumination device 10 turns on the visible light source 12 and turns off the infrared light source 11 using the switching unit 16, thereby irradiating the inspection object 3 with visible light from the side of the second layer 3b. In this case, the inspection object 3 is transported by the transport unit with the second layer 3b facing upward, toward the illumination device 10 and the imaging device 30. Note that the foreign matter X2 is removed by cleaning, and the foreign matter X3 is removed by CMP processing, and therefore is not shown in FIG. 5.

[0042] In this way, the foreign matter inspection system 1 uses infrared light to inspect for foreign matter before CMP in order to improve productivity and prevent equipment malfunctions during CMP, and after CMP, uses visible light to inspect for foreign matter in order to guarantee the performance of the SAW filter as a final product.

[0043] Here, the thickness of the second layer 3b, which is an LT layer, is on the order of several μm due to the CMP process. Therefore, there is a risk of interference and false defect detection due to unevenness in film thickness. In order to suppress unevenness in film thickness, it is necessary to irradiate visible light with a wide bandwidth. For example, if the thickness of the second layer 3b is 3 μm (3000 nm), the optical path difference due to the second layer 3b is calculated as 3000 nm × refractive index 2 × optical path round trip 2 = 12000 nm. In this case, the wave number is calculated by taking the reciprocal of the optical path difference, which is 833 cm -1 It is calculated as follows.

[0044] The wavelength range of the visible light irradiated by the lighting device 10 is 450 nm to 700 nm, and therefore the wavenumber is 14286 to 22222 cm -1 and the band width is approximately 8000 cm -1 That is, the visible light irradiated by the lighting device 10 has a bandwidth 8 to 10 times the optical path difference ΔL of the thickness of the second layer 3b after CMP. Therefore, it is possible to suppress unevenness in film thickness. On the other hand, the optical path difference due to voids is about 500 nm. That is, the wave number is about 20,000 cm -1 and the bandwidth of the visible light emitted by the lighting device 10 is approximately 8000 cm -1 Therefore, if voids exist, they can be stably imaged while suppressing unevenness in the film thickness.

[0045] <Imaging device 30> Returning to FIG. 1 , the imaging device 30 is a unit that captures an image of the inspection object 3 by capturing an image of the inspection object 3. The imaging device 30 is disposed above the inspection object 3 being transported by the transport unit, and receives light that is irradiated by the illumination device 10 and reflected by the inspection object 3. In this way, the imaging device 30 captures an image of a linear area that is an area where the inspection object 3 is irradiated with light by the illumination device 10.

[0046] The imaging device 30 includes a lens 31 that focuses visible light and infrared light, and an image sensor 32 that is sensitive to both visible light and infrared light. The imaging device 30 also includes an A / D (Analog / Digital) converter (not shown) that converts analog signals representing an image obtained by the image sensor 32 into digital data.

[0047] The image sensor 32 includes an imaging element having sensitivity in a wavelength range (for example, 400 to 1700 nm) that covers the visible and infrared ranges. The image sensor 32 is disposed at a light-collecting position by the lens 31. The image sensor 32 receives visible light and infrared light that are irradiated by the lighting device 10 and reflected by the inspection object 3, and generates a visible image and an infrared image.

[0048] More specifically, the image sensor 32 includes photodiodes arranged in an array and a readout circuit using a CMOS (Complementary Metal Oxide Semiconductor). The photodiodes are specifically made of InGaAs (indium gallium arsenide), a compound semiconductor. Visible light and infrared light incident on the image sensor 32 are photoelectrically converted by the photodiodes and read out as signals by the readout circuit. The signals read out by the image sensor 32 are output to the image processing device 50.

[0049] By using an image sensor 32 that is sensitive to such a wide wavelength range, it is possible to handle not only cases where the object of inspection 3 comprises a material that is transparent to visible light, but also cases where the object of inspection 3 comprises a material that is not transparent to visible light, such as silicon.

[0050] More specifically, when the lighting device 10 irradiates the inspection object 3 with infrared light, the imaging device 30 captures an image of the inspection object 3 with the infrared light, thereby obtaining an infrared image of the inspection object 3. On the other hand, when the lighting device 10 irradiates the inspection object 3 with visible light, the imaging device 30 captures an image of the inspection object 3 with visible light, thereby obtaining a visible image of the inspection object 3.

[0051] 6 shows, as an example, an infrared image P1 captured by the imaging device 30. The infrared image P1 is an image captured by the imaging device 30 when the illumination device 10 irradiates the inspection object 3 with infrared light from the side of the first layer 3a, as shown in FIG.

[0052] As shown in FIG. 6, the infrared image P1 is an image of the inspection object 3 before CMP captured using infrared light. The infrared image P1 captures foreign particles X1 to X3 contained in the inspection object 3 before CMP. Here, because the infrared image P1 was captured using a reflective optical system rather than a transmissive optical system, the foreign particle X1, which is a void, and the foreign particle X3, which is a depression, are captured as white regions. On the other hand, the foreign particle X2, which is a surface foreign particle attached to the surface of the inspection object 3, is captured as a black region, which is close to the color of the surrounding region other than the foreign particles X1 to X3. In this way, if the foreign particles X1 to X3 are present in the inspection object 3, they are captured as distinguishable regions in the infrared image P1.

[0053] 7 shows, as an example, a visible image P2 captured by the imaging device 30. The visible image P2 is an image captured by the imaging device 30 when the illumination device 10 irradiates the inspection object 3 with visible light from the side of the second layer 3b, as shown in FIG.

[0054] 7, the visible image P2 is an image of the inspection object 3 after CMP captured using visible light. In the visible image P2, foreign matter X1, which is a void contained in the inspection object 3 after CMP, is captured as a white area. In this way, if foreign matter X1 is present in the inspection object 3, it is captured as a distinguishable area in the visible image P2.

[0055] Note that the focus position on the image sensor 32 shifts between when the infrared image P1 and the visible image P2 are acquired due to lens chromatic aberration, differences in how the inspection object 3 is installed, and the like. To accommodate this shift in focus position, an area sensor capable of acquiring a two-dimensional image in a single imaging is used as the image sensor 32, rather than a line sensor, in order to acquire the focused infrared image P1 and visible image P2 using a single image sensor 32. The imaging device 30 does not use the entire area on the image sensor 32, which is an area sensor, but rather acquires the infrared image P1 and the visible image P2 based on the infrared light and visible light received only in a partial focused area, respectively.

[0056] Specifically, as shown in FIG. 8 , when infrared light is irradiated from the illumination device 10, the infrared light is reflected by the inspection object 3 being transported in a predetermined direction, and the reflected light is received by the imaging device 30. The optical path of the infrared light and the inspection object 3 onto which the infrared light is irradiated are indicated by dashed lines in FIG. 8 . At this time, the infrared light reflected at position R1 on the inspection object 3 passes through the lens 31 and is focused at position F1 on the image sensor 32. Position F1 is a position on a line passing through position R1 and the principal point of the lens 31. In this case, the imaging device 30 acquires an infrared image P1 based on the infrared light received in a first imaging area, which is an area centered at position F1. The first inspection area centered at position R1 on the inspection object 3 is captured in the infrared image P1. The imaging device 30 repeatedly acquires the infrared image P1 at a timing corresponding to the transport speed of the inspection object 3 transported by the transport unit. In this way, the entire area of ​​the inspection object 3 is captured using infrared light.

[0057] In contrast, when visible light is irradiated by the illumination device 10, the visible light is reflected by the inspection object 3 being transported in a predetermined direction, and the reflected light is received by the imaging device 30. The optical path of the visible light and the inspection object 3 onto which the visible light is irradiated are indicated by solid lines in FIG. 8 . The visible light reflected at position R2 on the inspection object 3 passes through the lens 31 and is focused at position F2 on the image sensor 32, which is offset from position F1. Position F2 is located on a line passing through position R2 and the principal point of the lens 31. In this case, the imaging device 30 captures a visible image P2 based on the visible light received in a second imaging area, which is an area centered at position F2. The visible image P2 captures a second inspection area centered at position R2 on the inspection object 3. The imaging device 30 repeatedly captures the visible image P2 at a timing corresponding to the transport speed of the inspection object 3 transported by the transport unit. This allows the entire area of ​​the inspection object 3 to be captured using visible light.

[0058] Here, the first imaging area and the second imaging area are different areas on the image sensor 32, but they may partially overlap. Areas that are in focus under individual inspection conditions are specified in advance by calibration, and the specified areas are set as the first imaging area and the second imaging area. Note that the imaging device 30 may use a region of interest (ROI) function in the process of generating an infrared image P1 from the first imaging area and the process of generating a visible image P2 from the second imaging area.

[0059] In this way, by using an area sensor, it is possible to adjust the shift in focus position caused by lens chromatic aberration and the like in a system that receives infrared light and visible light using a single image sensor 32. As a result, it is possible to acquire both an infrared image P1 and a visible image P2 at high resolution using a single image sensor 32. Furthermore, it is possible to flexibly deal with shifts in focus position caused by changes over time in the device.

[0060] However, the focus position deviation caused by chromatic aberration or the like may be adjusted by changing the direction of the optical axis of the image capturing device 30, which is indicated by the dashed line in Fig. 8. In this case, the first image capturing area and the second image capturing area may be fixed to the same area.

[0061] More specifically, although not shown, the imaging device 30 is equipped with a shift mechanism capable of shifting the position of the image sensor 32 in the direction of the optical axis of the imaging device 30, and the position of the image sensor 32 may be adjustable in the direction of the optical axis of the imaging device 30 by the shift mechanism. In this case, the imaging device 30 acquires an infrared image P1 when the position of the image sensor 32 in the direction of the optical axis is a first position, and acquires a visible image P2 when the position of the image sensor 32 in the direction of the optical axis is a second position different from the first position. In other words, the position of the image sensor 32 is changed in the direction of the optical axis between when acquiring the infrared image P1 and when acquiring the visible image P2.

[0062] By changing the position of the image sensor 32 in the direction of the optical axis in this manner, it is possible to adjust for shifts in the focus position due to lens chromatic aberration, etc. This makes it possible to acquire both the infrared image P1 and the visible image P2 in the same imaging area on the image sensor 32, making it possible to acquire focused infrared image P1 and visible image P2 while fixing the first imaging area and the second imaging area to the same area. Furthermore, if the position of the image sensor 32 can be shifted in the direction of the optical axis, it is possible to acquire the infrared image P1 and the visible image P2 in the same imaging area on the image sensor 32, so the image sensor 32 is not limited to being an area sensor and may be a line sensor.

[0063] <Image processing device 50> 1, the image processing device 50 is a unit that inspects the presence or absence of foreign matter inside the inspection object 3 based on the visible image P2 and the infrared image P1 acquired by the imaging device 30. The image processing device 50 is specifically an information processing device such as a personal computer or a cloud server.

[0064] As shown in FIG. 9, the image processing device 50 includes a control unit 51, a storage unit 52, an input receiving unit 53, a display unit 54, and a communication unit 55.

[0065] The control unit 51 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU includes a microprocessor and is a central processing unit that executes various processes and calculations. In the control unit 51, the CPU reads out a control program stored in the ROM and controls the overall operation of the image processing device 50 while using the RAM as a work memory. The control unit 51 may also include a processor for image processing, such as a DSP (Digital Signal Processor) or a GPU (Graphics Processing Unit).

[0066] The storage unit 52 is a non-volatile memory such as a flash memory, a hard disk, etc. The storage unit 52 stores programs and data executed by the control unit 51, and data generated by the control unit 51.

[0067] The input receiving unit 53 includes input devices such as a keyboard, a mouse, and a touch panel, and receives operation inputs from the user.

[0068] The display unit 54 includes a display device such as a liquid crystal display or an organic EL (Electro Luminescence) display, and displays various images under the control of the control unit 51. For example, the display unit 54 displays an image showing the inspection result by the foreign substance inspection system 1.

[0069] The communication unit 55 includes a communication interface for communicating with devices external to the image processing device 50, including the imaging device 30. For example, the communication unit 55 communicates with external devices in accordance with well-known communication standards such as LAN (Local Area Network) and USB (Universal Serial Bus).

[0070] The control unit 51 functionally comprises a cutout unit 110, a classification unit 120, and an output unit 130. In the control unit 51, the CPU reads a program stored in the ROM into the RAM, and executes and controls the program, thereby functioning as each of these units.

[0071] The cropping unit 110 crops out candidate areas that are candidates for voids, which are the detection targets, from each of the infrared image P1 and the visible image P2. Specifically, when the infrared image P1 is acquired by the imaging device 30, the cropping unit 110 analyzes the infrared image P1 using a well-known image processing technique. Then, the cropping unit 110 identifies areas in the infrared image P1 that satisfy specific conditions as candidate areas that may contain voids, and crops them out of the infrared image P1.

[0072] More specifically, the cropping unit 110 normalizes the pixel value (brightness value) of each pixel included in the infrared image P1 and performs binarization using a threshold value of about 1 to 2%. As a result of the binarization, the cropping unit 110 identifies areas in the infrared image P1 that are relatively brighter than other areas as candidate areas that may contain voids.

[0073] 6, when foreign substances X1 to X3 are captured in the infrared image P1, the cropping unit 110 treats the region of the foreign substance X2, which is nearly black, as the same region as the surrounding region other than the foreign substances X1 to X3 through binarization. Then, the cropping unit 110 excludes the region of the foreign substance X2 and the surrounding region from the infrared image P1, thereby cropping the regions of the foreign substances X1 and X3 from the surrounding region as candidate regions for voids.

[0074] Furthermore, when a visible image P2 is acquired by the imaging device 30, the cropping unit 110 crops out a candidate region by the same process as for the infrared image P1. For example, when a foreign object X1 is captured in the visible image P2 as shown in FIG. 7, the cropping unit 110 extracts the foreign object X1 by binarization. Other than Surrounding territories areaBy excluding the foreign substance X1 from the visible image P2, the region of the foreign substance X1 is cut out from the surrounding region as a candidate region for a void.

[0075] The classification unit 120 classifies the candidate regions extracted by the extraction unit 110. Then, based on the classification results of the candidate regions, the classification unit 120 determines whether or not there are foreign objects (voids) inside the inspection target 3. Specifically, the classification unit 120 calculates feature quantities that indicate the characteristics of the candidate regions. For example, the classification unit 120 calculates the size, circularity, etc. of the candidate regions as feature quantities. Then, based on the feature quantities, the classification unit 120 classifies the candidate regions into regions that correspond to voids, which are the detection targets, and regions that correspond to foreign objects other than voids.

[0076] For example, of the regions of foreign matter X1 and X3 cut out as candidate regions from infrared image P1, the region of foreign matter X1 is shaped like a circle, but the region of foreign matter X3 is shaped differently from a circle. Therefore, the classification unit 120 determines that foreign matter X1 corresponds to a void, but that foreign matter X3 does not correspond to a void. Furthermore, the classification unit 120 determines that the region of foreign matter X1 cut out as a candidate region from visible image P2 is shaped like a circle, so that foreign matter X1 corresponds to a void.

[0077] As a result of such classification, if there is an area corresponding to a void among the candidate objects extracted by the extraction unit 110, the classification unit 120 determines that there is a void inside the inspection object 3. Note that the classification unit 120 may combine the classification based on the above-mentioned features with machine learning techniques such as deep learning and random forest.

[0078] In this way, the image processing device 50 classifies the candidate areas cut out by the cut-out unit 110 using the classification unit 120, thereby suppressing over-detection and enabling high-accuracy detection of only voids, which are the foreign objects to be detected, from among multiple candidate areas.

[0079] Note that, because the imaging accuracy using visible light is generally higher than that using infrared light, the visible image P2 can detect smaller foreign particles (voids) than the infrared image P1. For example, small foreign particles that are not detected in the infrared image P1 may be detected in the visible image P2. Furthermore, foreign particles detected in the infrared image P1 may be removed by processes such as CMP or cleaning before the visible image P2 is acquired. Therefore, the foreign particles detected in the infrared image P1 and the foreign particles detected in the visible image P2 may be the same or different. When distinguishing between foreign particles detected in the infrared image P1 and foreign particles detected in the visible image P2, the foreign particle detected in the infrared image P1 may be referred to as a first foreign particle, and the foreign particle detected in the visible image P2 may be referred to as a second foreign particle.

[0080] The output unit 130 outputs the determination result by the classification unit 120, i.e., the inspection result by the foreign substance inspection system 1. For example, the output unit 130 displays an image indicating whether or not there is a void inside the inspection object 3 on the display unit 54, and notifies the user. Note that instead of or in addition to displaying the determination result on the display unit 54, the output unit 130 may output the determination result as audio, or may output the result to an external device via the communication unit 55.

[0081] Next, the flow of the foreign matter inspection process executed by the foreign matter inspection system 1 will be described with reference to the flowchart shown in FIG.

[0082] When the foreign substance inspection process starts, the transport unit transports the inspection object 3 with the first layer 3a, which is a silicon layer, facing the illumination device 10 and the imaging device 30. Then, the illumination device 10 turns on the infrared light source 11, and irradiates the inspection object 3 with infrared light from the side of the first layer 3a, as shown in FIG. 4 (step S1).

[0083] When the infrared light is irradiated, the imaging device 30 captures an image of the inspection object 3 using the irradiated infrared light. As a result, as shown in Fig. 6, for example, the imaging device 30 acquires an infrared image P1 of the inspection object 3 (step S2). Steps S1 and S2 are an example of a first acquisition step.

[0084] After acquiring the infrared image P1, the image processing device 50 determines whether or not a foreign substance (first foreign substance) that satisfies a predetermined condition is present inside the inspection target 3 based on the acquired infrared image P1 (step S3). Specifically, the image processing device 50 extracts candidate regions that are candidates for voids from the infrared image P1. The image processing device 50 then classifies the extracted candidate regions based on their features and determines whether or not the candidate regions correspond to voids based on the classification results. If the candidate regions correspond to voids, the image processing device 50 then determines whether or not the voids satisfy a predetermined condition. Here, the predetermined condition is a condition that is preset for determining whether or not polishing of the inspection target 3 can be performed normally. The predetermined condition is satisfied, for example, when the size of a foreign substance (void) present in the inspection target 3 is large enough to prevent normal polishing by CMP. Step S3 is an example of a first determination step.

[0085] If it is determined that a foreign substance satisfying the predetermined conditions is present inside the inspection object 3 (step S3; YES), the image processing device 50 skips the processes of steps S4 to S7, and outputs information indicating the presence of a foreign substance as the determination result in step S8. In this case, it is determined that if CMP is performed, there is a high possibility that maintenance of the CMP device will be required. Therefore, the user does not perform CMP in this state, but instead takes measures such as removing the foreign substance satisfying the predetermined conditions from the inspection object 3.

[0086] On the other hand, if it is determined that there is no foreign matter satisfying the predetermined condition in the inspection object 3 (step S3; NO), a dedicated CMP device performs CMP to polish the surface of the second layer 3b of the inspection object 3 (step S4). Step S5 is an example of a polishing step.

[0087] After CMP, the transport unit transports the inspection object 3 with the second layer 3b, which is the LT layer, facing the illumination device 10 and the imaging device 30. Then, as shown in FIG. 5, the illumination device 10 turns on the visible light source 12 to irradiate the inspection object 3 with visible light from the side of the second layer 3b that has been polished by the CMP process (step S5).

[0088] When the visible light is irradiated, the imaging device 30 captures an image of the inspection object 3 using the irradiated visible light. As a result, the imaging device 30 acquires a visible image P2 of the inspection object 3 (step S6), as shown in Fig. 7, for example. Steps S5 and S6 are an example of a second acquisition step.

[0089] After acquiring the visible image, the image processing device 50 determines whether or not there is a foreign substance (second foreign substance) inside the inspection object 3 based on the acquired visible image (step S7). Specifically, the image processing device 50 cuts out candidate areas that are candidates for voids from the visible image P2. The image processing device 50 then classifies the cut-out candidate areas based on their feature amounts, and determines whether or not the candidate areas correspond to voids based on the classification results. Step S7 is an example of a second determination step.

[0090] When determining whether or not a foreign substance is present, the image processing device 50 outputs the determination result (step S8). For example, if the image processing device 50 determines that a foreign substance is present, it displays an image indicating that fact on the display unit 54, and if it determines that no foreign substance is present, it displays an image indicating that fact on the display unit 54. This completes the foreign substance inspection process shown in FIG. 10.

[0091] As described above, the foreign matter inspection system 1 according to this embodiment irradiates the inspection object 3 with visible light and infrared light, and inspects the presence or absence of foreign matter inside the inspection object 3 based on a visible image P2 in which the inspection object 3 is captured using visible light and an infrared image P1 in which the inspection object 3 is captured using infrared light. In this way, by using infrared light, the foreign matter inspection system 1 according to this embodiment can inspect the presence or absence of foreign matter inside the inspection object even when inspection is difficult using visible light. On the other hand, by using visible light, the foreign matter inspection system 1 according to this embodiment can also perform foreign matter inspection with high accuracy. As a result, the foreign matter inspection system 1 according to this embodiment can flexibly inspect the presence or absence of foreign matter inside the inspection object 3 depending on the situation.

[0092] In particular, the foreign substance inspection system 1 according to this embodiment acquires a visible image P2 and an infrared image P1 using a single image sensor 32 that is sensitive to both visible light and infrared light. Because both the visible image P2 and the infrared image P1 can be acquired using a single image sensor 32, there is no need to provide two imaging systems, which reduces the size and cost of the device and leads to a smaller and lighter device.

[0093] Furthermore, since the visible image P2 and the infrared image P1 are acquired by a single image sensor 32, the accuracy of positional matching between the visible image P2 and the infrared image P1 is improved. As a result, for example, if the same void is captured in the visible image P2 and the infrared image P1, the position of the void in the visible image P2 and the position of the void in the infrared image P1 can be accurately correlated and output to the user. As a result, the user can easily compare and analyze the void captured in the visible image P2 and the void captured in the infrared image P1, for example.

[0094] Furthermore, the foreign particle inspection system 1 according to this embodiment irradiates the inspection target 3 with infrared light from the side of the first layer 3a before CMP is performed on the second layer 3b, and irradiates the inspection target 3 with visible light from the side of the second layer 3b after CMP is performed on the second layer 3b. If inspection using visible light is difficult before CMP, the presence or absence of voids, such as substrate cracks that directly affect equipment maintenance, can be inspected using infrared light. Conversely, after CMP, in processes aimed at ensuring product quality, such as shipping inspection, the presence or absence of voids can be inspected using visible light. In this way, foreign particle inspection can be performed using light of different wavelengths before and after CMP, allowing for flexible inspections required at each step in the manufacture of SAW filters.

[0095] Furthermore, the lighting device 10 according to this embodiment includes an infrared light source 11, a visible light source 12, and a rod-shaped transmission member 13. The infrared light emitted from the infrared light source 11 enters one end of the transmission member 13 and exits from its side, while the visible light emitted from the visible light source 12 enters the other end of the transmission member 13 and exits from its side. By using the rod-shaped transmission member 13, it is possible to irradiate the inspection object 3 with visible light and infrared light while suppressing unevenness in brightness and wavelength. In particular, when inspecting for voids with a diameter of 10 μm, the contrast between areas with voids and areas without voids in the image captured by the imaging device 30 is only a few percent. Therefore, to accurately detect voids, it is important to sufficiently suppress unevenness in brightness and wavelength of the visible light and infrared light irradiated from the lighting device 10.

[0096] Furthermore, the illumination device 10 according to this embodiment turns on only the infrared light source 11 during pre-CMP inspection and turns on only the visible light source 12 during post-CMP inspection, thereby making it possible to easily switch between irradiating infrared light and visible light from a single transmission member 13. As a result, the illumination device 10 according to this embodiment can realize a foreign matter inspection system 1 that can flexibly inspect the presence or absence of foreign matter inside the inspection object 3 according to the situation, while realizing a reduction in the size and weight of the device.

[0097] (Variation) Although the embodiments of the present invention have been described above, it is possible to combine the embodiments, or to modify or omit the embodiments as appropriate.

[0098] For example, in the above embodiment, inspection object 3 is a SAW filter that is a laminate of a silicon wafer and a lithium tantalate (LT) wafer. However, the lithium tantalate wafer may be a lithium niobate (LiNbO) wafer. Furthermore, inspection object 3 is not limited to being a SAW filter and may be an object made of any material.

[0099] The first layer 3a and the second layer 3b may be wafers made of materials other than those mentioned above. For example, the first layer 3a may be made of lithium tantalate, lithium niobate, sapphire, alumina (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), zirconia (ZrO2), glass, or the like, in addition to silicon. The second layer 3b may be made of silicon, GaAs, SiC, GaN, ZnO, PZT, or the like, in addition to lithium tantalate or lithium niobate. Even if the first layer 3a or the second layer 3b is made of a wafer of such a material, if either layer is made of a material that does not transmit visible light, such as silicon, the presence or absence of foreign matter can be inspected by irradiating infrared light from the layer side using the above-described foreign matter inspection system 1. On the other hand, if either layer is made of a material that transmits visible light, such as LT or NT, the presence or absence of foreign matter can be inspected by irradiating visible light from the layer side.

[0100] In the above embodiment, the foreign matter inspection system 1 performs foreign matter inspection using both visible light and infrared light. However, depending on the material of the inspection object 3, the foreign matter inspection system 1 may perform foreign matter inspection using only visible light or only infrared light.

[0101] The wavelengths of the visible light and infrared light irradiated by the illumination device 10 can be appropriately selected optimally in consideration of the thickness of each layer included in the inspection object 3 and the size of the foreign matter to be inspected. When inspecting a plurality of different types of inspection objects 3, it may be possible to switch the wavelength of the visible light or infrared light irradiated by the illumination device 10.

[0102] Furthermore, the foreign matter inspected by the foreign matter inspection system 1 is not limited to the voids described above, as long as it is a foreign matter present inside the inspection object 3. For example, the foreign matter inspected by the foreign matter inspection system 1 may be a contaminant that has become mixed inside the inspection object 3. By appropriately changing the classification conditions in the classification unit 120 of the image processing device 50 so that foreign matters other than voids can be detected from the infrared image P1 and the visible image P2, it is also possible to apply the method described in the above embodiment to the inspection of foreign matters other than voids.

[0103] In the above embodiment, the lighting device 10 selectively irradiates the inspection object 3 with visible light and infrared light. However, the lighting device 10 may irradiate the inspection object 3 with light including both the visible light and infrared light wavelength ranges, thereby simultaneously irradiating the inspection object 3 with visible light and infrared light. In this case, the imaging device 30 acquires a single captured image captured using both visible light and infrared light. The image processing device 50 extracts the infrared light wavelength component from the acquired single captured image to acquire an infrared image P1, and extracts the visible light wavelength component from the acquired single captured image to acquire a visible image P2. The image processing device 50 then performs the same processing as in the above embodiment on the infrared image P1 and the visible image P2.

[0104] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined not by the embodiments but by the claims. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention. [Explanation of symbols]

[0105] 1 Foreign body inspection system, 3 Inspection object, 3a, 3b Layer, 10 Illumination device, 11 Infrared light source, 12 Visible light source, 13 Transmission member, 13a Reflector, 14 Infrared light transmission filter, 15 Visible light transmission filter, 16 Switching unit, 30 Imaging device, 31 Lens, 32 Image sensor, 50 Image processing device, 51 Control unit, 52 Memory unit, 53 Input reception unit, 54 Display unit, 55 Communication unit, 110 Cutting unit, 120 Classification unit, 130 Output unit, F1, F2, R1, R2 Position, P1 Infrared image, P2 Visible image, X1 to X3 Foreign body

Claims

1. an illumination device that irradiates the inspection object with visible light and infrared light; an imaging device that acquires a visible image of the inspection object captured by the visible light irradiated by the lighting device and an infrared image of the inspection object captured by the infrared light irradiated by the lighting device; an image processing device that inspects the presence or absence of foreign matter inside the inspection object based on the visible image and the infrared image acquired by the imaging device, The image processing device includes: determining whether or not a first foreign matter that satisfies a predetermined condition exists inside the inspection object based on the infrared image obtained by capturing the inspection object using the infrared light before the polishing process is performed; when it is determined that the first foreign matter satisfying a predetermined condition is not present inside the inspection object, the presence or absence of a second foreign matter inside the inspection object is determined based on the visible image obtained by capturing the inspection object using the visible light after the polishing process has been performed. Foreign object inspection system.

2. the imaging device includes a single image sensor that is sensitive to both the visible light and the infrared light, and the single image sensor acquires the visible image and the infrared image. The foreign matter inspection system according to claim 1 .

3. The imaging device is When the infrared light is emitted by the lighting device, the infrared image is acquired based on the infrared light received in a first imaging area on the image sensor; When the visible light is irradiated by the illumination device, the visible image is acquired based on the visible light received in a second imaging area on the image sensor. The foreign matter inspection system according to claim 2 .

4. the position of the image sensor is shiftable in the direction of the optical axis of the imaging device; The imaging device is acquiring the infrared image when the position of the image sensor in the direction of the optical axis is a first position; acquiring the visible image when the position of the image sensor in the direction of the optical axis is a second position different from the first position; 4. The foreign matter inspection system according to claim 2 or 3.

5. the illumination device irradiates the visible light and the infrared light from an oblique direction onto a surface of the inspection object being transported in a predetermined direction; the imaging device receives reflected light of the visible light and the infrared light irradiated from the lighting device, and acquires the visible image and the infrared image based on the received reflected light. The foreign matter inspection system according to claim 1 .

6. the test object includes a first layer and a second layer; the image processing device inspects for the presence or absence of a void between the first layer and the second layer as the foreign matter; The foreign matter inspection system according to claim 1 .

7. the illumination device irradiates the inspection object with the infrared light from the first layer side and with the visible light from the second layer side; The foreign matter inspection system according to claim 6 .

8. the first layer has a property of not transmitting visible light, the illumination device irradiates the inspection object with the infrared light from the side of the first layer before the polishing process is performed on the second layer, and irradiates the inspection object with the visible light from the side of the second layer after the polishing process is performed on the second layer. The foreign matter inspection system according to claim 7 .

9. the first layer is a layer of silicon; the second layer is a layer of lithium tantalate or lithium niobate; The foreign matter inspection system according to any one of claims 6 to 8.

10. The image processing device includes: a cutout unit that cuts out candidate regions that are candidates for the foreign matter from each of the infrared image and the visible image; a classification unit that classifies the candidate region extracted by the extraction unit and determines the presence or absence of the foreign matter inside the inspection object based on a classification result of the candidate region. The foreign matter inspection system according to any one of claims 1 to 9.

11. The lighting device includes: an infrared light source that emits the infrared light; a visible light source that emits the visible light; a rod-shaped transmission member that transmits the infrared light and the visible light; a switching unit that switches the infrared light source on and off and the visible light source on and off, the infrared light emitted from the infrared light source enters the transmission member from one end thereof and exits from a side surface of the transmission member; the visible light emitted from the visible light source enters the transmission member from the other end of the transmission member and exits from the side surface of the transmission member; The foreign matter inspection system according to any one of claims 1 to 10.

12. The lighting device includes: an infrared light transmission filter at the one end of the transmission member, the infrared light transmission filter transmitting the infrared light and reflecting the visible light; a visible light transmission filter at the other end of the transmission member, the visible light being transmitted therethrough and the infrared light being reflected therefrom; the infrared light emitted from the infrared light source passes through the infrared light transmission filter and enters the transmission member from the one end of the transmission member; the visible light emitted from the visible light source passes through the visible light transmission filter and enters the transmission member from the other end of the transmission member; The foreign matter inspection system according to claim 11.

13. a first acquisition step of irradiating an inspection object with infrared light to acquire an infrared image of the inspection object captured with the infrared light; a first determination step of determining whether or not a first foreign matter that satisfies a predetermined condition exists inside the inspection object based on the infrared image acquired in the first acquisition step; a polishing step of polishing the inspection object when it is determined in the first determination step that the first foreign matter satisfying a predetermined condition is not present inside the inspection object; a second acquisition step of irradiating the inspection object polished in the polishing step with visible light to acquire a visible image of the inspection object captured with the visible light; a second determination step of determining the presence or absence of a second foreign matter inside the inspection object based on the visible image acquired in the second acquisition step, Foreign body inspection method.

Images