Inspection device and inspection method

Abstract

This inspection device is for inspecting a PIC and comprises: an XY stage on which the PIC is placed; a condensing optical system that is disposed so as to face the XY stage and condenses light output from the PIC; an intensity / wavelength information acquisition unit that acquires spatial distribution data of intensity information and wavelength information of the light condensed by the condensing optical system; a storage unit that stores CAD data, which is design information of the PIC; and a computer that generates an inspection image on the basis of the spatial distribution data and the CAD data.

Description

Inspection Device and Inspection Method

[0001] The present disclosure relates to an inspection device and an inspection method.

[0002] In recent years, the development of photonic integrated circuits (PICs) has been progressing. A photonic integrated circuit is a device that integrates various optical functions and transmits information signals by light. As a method for inspecting a photonic integrated circuit, there is known a method of imaging infrared light scattered by a defect in a waveguide in the photonic integrated circuit and displaying the captured image on a display to grasp the spatial position of the defect (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-58070

[0004] Here, the amount of light leaking from the waveguide in the photonic integrated circuit varies greatly depending on the material, structure, and environmental conditions of the photonic integrated circuit. Therefore, it may not be possible to accurately grasp the spatial position of a defect or the like only by the method of simply imaging infrared light, and it is conceivable that an appropriate inspection cannot be performed on the photonic integrated circuit.

[0005] The present disclosure has been made in view of the above circumstances, and relates to an inspection device and an inspection method capable of appropriately inspecting a photonic integrated circuit.

[0006] An inspection device according to an aspect of the present disclosure is [1] "an inspection device for inspecting a photonic integrated circuit, comprising: a stage on which the photonic integrated circuit is placed; a condensing optical system arranged to face the stage and condensing the light output from the photonic integrated circuit; an intensity / wavelength information acquisition unit that acquires spatial distribution data of intensity information and wavelength information of the light condensed by the condensing optical system; a storage unit that stores CAD data, which is design information of the photonic integrated circuit; and an analysis unit that generates an inspection image based on the spatial distribution data and the CAD data."

[0007] In one aspect of the present disclosure, spatial distribution data of light intensity information and wavelength information output from a photonic integrated circuit and focused by a focusing optical system is acquired, and an inspection image is generated based on this spatial distribution data and CAD data, which is the design information of the photonic integrated circuit. In this way, by generating an inspection image from spatial distribution data of light intensity information and wavelength information, it is possible to generate an inspection image that appropriately considers the light information. Furthermore, in one aspect of the present disclosure, since the inspection image is generated by considering CAD data, which is the design information of the photonic integrated circuit, in addition to the spatial distribution data, it is possible to generate an inspection image by accurately identifying the spatial location of defects, for example, which is difficult to grasp from light information (intensity information and wavelength information) alone, using the CAD data, which is the design information. This improves the inspection accuracy of the photonic integrated circuit. As described above, the inspection device according to one aspect of the present disclosure can appropriately inspect a photonic integrated circuit.

[0008] An inspection apparatus according to one aspect of the present disclosure may be [2] "an inspection apparatus according to [1] in which the analysis unit generates an inspection image by superimposing CAD data onto a spatial distribution image of at least one of intensity information and wavelength information based on spatial distribution data." In this way, by superimposing CAD data onto the spatial distribution image, it is possible to appropriately determine, for example, which structure in the photonic integrated circuit is responsible for the observed leak light. This makes it possible to improve the inspection accuracy of the photonic integrated circuit.

[0009] An inspection apparatus according to one aspect of the present disclosure may be [3] "an inspection apparatus according to [1] or [2] wherein the analysis unit further sets an acquisition range in which spatial distribution data is acquired by the intensity / wavelength information acquisition unit based on CAD data, and the intensity / wavelength information acquisition unit acquires spatial distribution data in the acquisition range set by the analysis unit." In this way, by setting the acquisition range of spatial distribution data based on CAD data, it becomes possible to acquire spatial distribution data specifically in areas where leakage light is likely to occur (for example, areas with a tight radius in the waveguide, areas with rough side walls, areas entering different structures, etc.), thereby improving inspection efficiency.

[0010] An inspection apparatus according to one aspect of the present disclosure may be [4] "an inspection apparatus according to any one of [1] to [3], wherein the analysis unit sets an analysis area in the spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data." In this way, by limiting the analysis area based on CAD data, it becomes possible to generate inspection images specifically for areas where light leakage is likely to occur, for example, thereby improving inspection efficiency.

[0011] An inspection apparatus according to one aspect of the present disclosure may be [5] "an inspection apparatus according to any one of [1] to [4], wherein the analysis unit acquires design information for a specific location in a spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data." With such a configuration, for example, it becomes possible to identify the cause of light leakage by checking the design information of the location where light leakage occurs (such as the width, thickness, shape of the waveguide and the state of the upper and lower layers).

[0012] An inspection apparatus according to one aspect of the present disclosure may be [6] "an inspection apparatus according to any one of [1] to [5], wherein the intensity and wavelength information acquisition unit acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data." With such a configuration, based on the intensity distribution image and centroid wavelength distribution image, which can be acquired relatively quickly, it is possible to identify, for example, a location in the waveguide where the optical information differs from that of other parts as an abnormal location.

[0013] An inspection apparatus according to one aspect of the present disclosure may be [7] "an inspection apparatus according to any one of [1] to [6], wherein the intensity / wavelength information acquisition unit acquires a wavelength-specific intensity distribution image, which is a spatial distribution image for each wavelength of light focused by the focusing optical system, based on spatial distribution data." By acquiring a wavelength-specific intensity distribution image in this manner, it becomes possible to generate a wavelength spectral distribution image, as described later, and to identify the wavelength dependence of the intensity distribution.

[0014] An inspection apparatus according to one aspect of the present disclosure may be [8] "an inspection apparatus according to [7] in which the analysis unit generates a wavelength spectral distribution image, which is an inspection image, based on a wavelength-specific intensity distribution image." By generating a wavelength spectral distribution image, it is possible to identify whether the intensity distribution is wavelength-dependent or not, and for example, the cause of leaked light can be identified with high accuracy.

[0015] An inspection apparatus according to one aspect of this disclosure may be [9] "an inspection apparatus according to [8] in which the analysis unit identifies the cause of an anomaly in a photonic integrated circuit based on the shape of the wavelength spectrum in a wavelength spectrum distribution image." From the shape of the wavelength spectrum, for example, the wavelength dependence of leaked light can be identified with high accuracy. By considering such wavelength dependence of leaked light, the cause of an anomaly in a photonic integrated circuit can be identified with high accuracy.

[0016] An inspection apparatus according to one aspect of the present disclosure may be

[10] "an inspection apparatus according to any one of [1] to [9], having: a first acquisition unit that acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data; a second acquisition unit that acquires wavelength-specific intensity distribution images, which are spatial distribution images for each wavelength of light focused by a focusing optical system, based on spatial distribution data; and a switching unit that switches between acquiring the intensity distribution image and centroid wavelength distribution image by the first acquisition unit and acquiring the wavelength-specific intensity distribution image by the second acquisition unit." In this way, by switching between the first acquisition unit and the second acquisition unit, for example, when confirming whether there are any abnormalities in the waveguide, the acquisition results obtained by the first acquisition unit, which can be obtained relatively quickly, can be taken into consideration, and if there are abnormalities, the acquisition results obtained by the second acquisition unit, which is suitable for identifying the cause of the abnormality can be taken into consideration, and the acquisition means can be changed according to the purpose, making it possible to inspect photonic integrated circuits more appropriately.

[0017] An inspection method according to one aspect of the present disclosure may be

[11] "an inspection method for inspecting a photonic integrated circuit, comprising: a focusing step of focusing light output from a photonic integrated circuit using a focusing optical system arranged opposite to a stage on which the photonic integrated circuit is mounted; an intensity / wavelength information acquisition step of acquiring spatial distribution data of intensity information and wavelength information of the light focused by the focusing optical system; and an analysis step of generating an inspection image based on the spatial distribution data and CAD data, which is design information of the photonic integrated circuit stored in a memory unit."

[0018] In one aspect of the present disclosure, spatial distribution data of light intensity information and wavelength information output from a photonic integrated circuit and focused by a focusing optical system is acquired, and an inspection image is generated based on this spatial distribution data and CAD data, which is the design information of the photonic integrated circuit. In this way, by generating an inspection image from spatial distribution data of light intensity information and wavelength information, it is possible to generate an inspection image that appropriately considers the light information. Furthermore, in one aspect of the present disclosure, since the inspection image is generated by considering CAD data, which is the design information of the photonic integrated circuit, in addition to the spatial distribution data, it is possible to generate an inspection image by accurately identifying the spatial location of defects, for example, which is difficult to grasp from light information (intensity information and wavelength information) alone, using the CAD data, which is the design information. This improves the inspection accuracy of the photonic integrated circuit. As described above, the inspection method in one aspect of the present disclosure allows for appropriate inspection of a photonic integrated circuit.

[0019] An inspection method according to one aspect of the present disclosure may be

[12] "the inspection method according to

[11] , wherein the analysis step is to generate an inspection image by superimposing CAD data onto a spatial distribution image of at least one of intensity information and wavelength information based on spatial distribution data." By superimposing CAD data onto the spatial distribution image in this way, it is possible to appropriately determine, for example, which structure in the photonic integrated circuit is responsible for the observed leak light. This improves the inspection accuracy of the photonic integrated circuit.

[0020] An inspection method according to one aspect of the present disclosure may be

[13] "the inspection method according to

[11] or

[12] , wherein the analysis step further sets an acquisition range in which spatial distribution data is acquired by the intensity / wavelength information acquisition step based on CAD data, and the intensity / wavelength information acquisition step acquires spatial distribution data in the acquisition range set by the analysis step." In this way, by setting the acquisition range of spatial distribution data based on CAD data, it becomes possible to acquire spatial distribution data specifically in areas where leakage light is likely to occur (for example, areas with a tight radius in the waveguide, areas with rough side walls, areas entering different structures, etc.), thereby improving inspection efficiency.

[0021] An inspection method according to one aspect of the present disclosure may be

[14] "the inspection method according to any one of

[11] to

[13] , wherein the analysis step sets an analysis area in the spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data." In this way, by limiting the analysis area based on CAD data, it becomes possible to generate inspection images specifically for areas where light leakage is likely to occur, for example, thereby improving inspection efficiency.

[0022] An inspection method according to one aspect of the present disclosure may be

[15] "an inspection method according to any one of

[11] to

[14] , wherein the analysis step is to acquire design information for a specific location in a spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data." With such a configuration, for example, it becomes possible to identify the cause of the leakage light by checking the design information of the location where the leakage light is occurring (such as the width, thickness, shape of the waveguide and the state of the upper and lower layers).

[0023] An inspection method according to one aspect of the present disclosure may be

[16] "an inspection method according to any one of

[11] to

[15] , wherein the intensity and wavelength information acquisition step is to acquire an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data." With such a configuration, based on the intensity distribution image and centroid wavelength distribution image, which can be acquired relatively quickly, it is possible to identify, for example, a location in the waveguide where the optical information differs from that of other parts as an abnormal location.

[0024] The inspection method according to one aspect of the present disclosure may be

[17] "the inspection method according to any one of

[11] to

[16] , wherein the intensity and wavelength information acquisition step is to acquire a wavelength-specific intensity distribution image, which is a spatial distribution image of each wavelength of light focused by a focusing optical system, based on spatial distribution data." By acquiring a wavelength-specific intensity distribution image in this way, it becomes possible to generate a wavelength spectral distribution image, which will be described later, and to identify the wavelength dependence of the intensity distribution.

[0025] An inspection method according to one aspect of the present disclosure may be the inspection method according to

[17] , wherein the analysis step generates a wavelength spectral distribution image, which is an inspection image, based on a wavelength-specific intensity distribution image. By generating a wavelength spectral distribution image, it is possible to identify whether the intensity distribution is wavelength-dependent or not, and for example, the cause of leaked light can be identified with high accuracy.

[0026] An inspection method according to one aspect of this disclosure may be

[19] "the inspection method according to [8], wherein the analysis step identifies the cause of an anomaly in a photonic integrated circuit based on the shape of the wavelength spectrum in a wavelength spectrum distribution image." From the shape of the wavelength spectrum, for example, the wavelength dependence of leaked light can be identified with high accuracy. By considering such wavelength dependence of leaked light, the cause of an anomaly in a photonic integrated circuit can be identified with high accuracy.

[0027] An inspection method according to one aspect of the present disclosure may be

[20] "an inspection method according to any one of

[11] to

[19] , comprising: a first acquisition step of acquiring an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data; a second acquisition step of acquiring a wavelength-specific intensity distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data; and a switching step of switching between acquiring the intensity distribution image and centroid wavelength distribution image by the first acquisition step and acquiring the wavelength-specific intensity distribution image by the second acquisition step." In this way, by switching between the first acquisition step and the second acquisition step, for example, confirmation of whether there are abnormal locations in the waveguide can be performed considering the acquisition results obtained by the first acquisition step, which can be obtained relatively quickly, and if there are abnormal locations, the acquisition can be performed considering the acquisition results obtained by the second acquisition step, which is suitable for identifying the cause of the abnormality, thereby enabling a more appropriate inspection of the photonic integrated circuit.

[0028] According to this disclosure, photonic integrated circuits can be properly inspected.

[0029] Figure 1 is a schematic diagram of the inspection apparatus according to this embodiment. Figure 2 is a diagram illustrating analysis using CAD data. Figure 3 is a diagram illustrating an example configuration of the intensity / wavelength information acquisition unit. Figure 4 is a diagram illustrating the characteristics of the light spectrum and LRG filter. Figure 5 is a diagram illustrating the display of intensity information and wavelength information. Figure 6 is a diagram illustrating analysis using CAD data. Figure 7 is a diagram illustrating the intensity / wavelength information acquisition unit according to a modified example. Figure 8 is a diagram illustrating analysis using CAD data. Figure 9 is a schematic diagram of the inspection apparatus according to a modified example. Figure 10 is a flowchart of the inspection method. Figure 11 is a flowchart of the inspection method. Figure 12 is a flowchart of the inspection method. Figure 13 is a flowchart of the inspection method. Figure 14 is a flowchart of the inspection method. Figure 15 is a flowchart of the inspection method. Figure 16 is a flowchart of the inspection method.

[0030] Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

[0031] Figure 1 is a schematic diagram of the inspection apparatus 1 according to this embodiment. The inspection apparatus 1 is an apparatus for inspecting a photonic integrated circuit (PIC: Photonic IC) 100. The PIC 100 is a circuit that integrates multiple photonic components such as waveguides, laser elements, modulators, detectors, and light sources onto a single chip. Compared to conventional integrated circuits such as silicon ICs, the PIC 100 has superior speed, broad bandwidth, and power efficiency. Furthermore, the inspection here may include not only checking whether there are any abnormalities (defects) in the PIC 100, but also generating information necessary for controlling the PIC 100, for example. The inspection apparatus 1 detects the light output from the PIC 100, derives intensity information and wavelength information of the light, and inspects the PIC 100 using the intensity information and wavelength information. By deriving the intensity and wavelength information of the light output from PIC100, it is possible to inspect whether light of the desired wavelength is being output (channel accuracy, stability of light output), whether there are any problems with the electrical and optical connections of the laser element in PIC100, whether there are any defects in the waveguide in PIC100 (presence or absence of leaked light, degree of leaked light), and whether the optical transmission characteristics (wavelength-transmittance) of the waveguide are appropriate.

[0032] Figure 2 is a diagram illustrating analysis using CAD data. In the inspection apparatus 1 according to this embodiment, CAD data is used in addition to light intensity information and wavelength information to inspect the PIC 100. Figure 2(a) is an intensity distribution image obtained by spatially mapping the light intensity information output from the PIC 100. In the example shown in Figure 2(a), a region 201 with different intensity information compared to others is shown. This region 201 is the waveguide region. Figure 2(b) is a diagram showing the CAD data of the PIC 100. As shown in Figure 2(b), let's assume that the PIC 100 actually has two waveguides 301 and 302. Now, as shown in Figure 2(a), let's assume that only the region 201 corresponding to waveguide 301 is displayed separately from the two waveguides 301 and 302. In such cases, for example, as shown in Figure 2(c), when the intensity distribution image (Figure 2(a)) and CAD data (Figure 2(b)) are superimposed on each other, it becomes clear that only the region 201 corresponding to waveguide 301 among waveguides 301 and 302 is shown in the intensity distribution image. In this way, by superimposing CAD data on the intensity distribution image (spatial distribution image), it becomes possible to appropriately understand, for example, which structure in the PIC100 is responsible for the observed leaked light.

[0033] Returning to Figure 1, the inspection device 1 comprises an XY stage 10 (stage), a light source 20, a focusing optical system 30, an intensity / wavelength information acquisition unit 50, a Z stage 60, a computer 70 (analysis unit), and a storage unit 80.

[0034] The XY stage 10 is a stage on which the PIC 100 is mounted. The XY stage 10 mounts and holds the PIC 100. The XY stage 10 is configured to allow the PIC 100 to move in the XY directions (front-back and left-right directions) in order to adjust the position of the PIC 100 relative to the field of view (observation range) of the optical system. Note that this function of adjusting the position in the XY direction may be provided on the optical system side rather than on the stage.

[0035] The Z-stage 60 moves the focusing optical system 30 and the intensity / wavelength information acquisition unit 50 together in the optical axis direction (Z-direction) of the optical system. This allows for adjustment of the focal position of the optical system relative to the PIC 100. Note that this Z-direction position adjustment function may be provided in the XY stage 10 instead of the optical system.

[0036] The light source 20 is a light source that emits measurement light having a predetermined wavelength band in accordance with the control of the computer 70. The measurement light emitted from the light source 20 is input to the optical input terminal of the PIC 100. The light source 20 may also emit measurement light having a predetermined wavelength band in accordance with the control of a control device other than the computer 70.

[0037] The PIC100 is a device that integrates various optical functions and transmits information signals by light. The PIC100 is composed of various elements. The PIC100 includes an optical input section, an optical output section, a grating coupler, a laser element, an input coupler, an optical modulator, an optical coupler, waveguides 108 and 109, a photodiode, an optical ring resonant circuit 110, a photonic crystal, and the like. The PIC100 has at least one optical output section and a waveguide.

[0038] The optical input section is the part into which light is input from outside the PIC 100 to the inside of the PIC 100. The optical input section may be formed on the input end face, which is one side of the PIC 100. Multiple optical input sections are formed on this input end face. For example, in the put-together state after testing, optical cables are connected to the optical input section. The optical output section is the part that outputs light to the outside of the PIC 100. The optical output section may be formed on the output end face, which is the other end face of the PIC 100. Multiple optical output sections are formed on this output end face. For example, in the put-together state after testing, optical cables are connected to the optical output section. The optical output section may output light that has been input from the optical input section and guided by waveguides 108 and 109 to the outside of the PIC 100.

[0039] The grating coupler is located on the front (top) surface of the PIC100 and functions as an optical output unit that outputs light upward (outside the PIC100). The laser element is a light source that emits laser light into the PIC100. The light emitted from the laser element reaches the optical coupler via the input coupler and optical modulator, and is guided by waveguides 108 and 109. The photodiode is a photodetector provided inside the PIC100. The optical ring resonant circuit 110 is a circuit that sets the resonant wavelength. The photonic crystal is a structure in which the refractive index changes periodically, and is a structure that confines light to a small region and manipulates light. Note that the PIC100 may include various elements in addition to the components (elements) described above. For example, the PIC100 may have microheaters (not shown) mounted on each element such as the optical ring resonant circuit 110 or the optical modulator. The microheater is configured to control the resonant wavelength of the light guided by changing the refractive index of the waveguides that make up each element, such as the optical ring resonant circuit 110 or the optical modulator.

[0040] The focusing optical system 30 is positioned opposite the XY stage 10 and is an optical system that focuses the light output from the PIC 100 (specifically, the measurement light that leaks from the PIC 100 after being guided through the waveguides 108 and 109 of the PIC 100). The focusing optical system 30 guides the measurement light to the intensity and wavelength information acquisition unit 50. The focusing optical system 30 has a plurality of objective lenses 31 with different magnifications and a revolving nosepiece 32 that holds the plurality of objective lenses 31.

[0041] The intensity / wavelength information acquisition unit 50 acquires spatial distribution data of intensity and wavelength information of the measurement light focused by the focusing optical system 30. Figure 3 is a diagram illustrating an example of the configuration of the intensity / wavelength information acquisition unit 50. As shown in Figure 3(a), the intensity / wavelength information acquisition unit 50 is configured to include an LRG (Linear Reflectance Gradient on the wavelength axis) filter 51, a first image sensor 52, and a second image sensor 53.

[0042] The LRG filter 51 is a dichroic mirror made using a special optical material, and separates light from the PIC 100 by transmitting and reflecting it according to its wavelength. The LRG filter 51 has transmission characteristics in which the transmittance changes linearly in a predetermined wavelength range, and transmits and reflects the light that is guided by the waveguides 108 and 109 in the PIC 100 and output from the optical output section based on the above transmission characteristics.

[0043] Figure 4 illustrates the characteristics of the light spectrum and the LRG filter 51. In Figure 4, the horizontal axis represents wavelength, and the vertical axis represents spectral intensity, which is luminance (in the case of the light spectrum) and transmittance (in the case of the LRG filter 51). As shown in the characteristics X4 of the LRG filter 51 in Figure 4, in the LRG filter 51, in a predetermined wavelength range (wavelength band λ1 to λ2), the transmittance (and reflectance) of light changes gradually in accordance with the change in wavelength, while in wavelength bands other than the predetermined wavelength range (i.e., wavelengths lower than λ1 and wavelengths higher than λ2), the transmittance (and reflectance) of light remains constant regardless of the change in wavelength. In other words, in a predetermined wavelength range (wavelength band λ1 to λ2), the transmittance of light increases monotonically (reflectance decreases monotonically) in accordance with the change in wavelength. Since transmittance and reflectance have a negative correlation, where an increase in one leads to a decrease in the other, the term "transmittance (and reflectance)" may be used below instead of simply "transmittance." Furthermore, "the transmittance of light is constant regardless of the change in wavelength" includes not only cases where it is perfectly constant, but also cases where, for example, the change in transmittance for a change of 1 nm in wavelength is 0.1% or less. At wavelengths lower than λ1, the transmittance of light is approximately 0% regardless of the change in wavelength, and at wavelengths higher than λ2, the transmittance of light is approximately 100% regardless of the change in wavelength. Furthermore, "the transmittance of light is approximately 0%" includes transmittances of approximately 0% + 10%, and "the transmittance of light is approximately 100%" includes transmittances of approximately 100% - 10%. As described above, the LRG filter 51 is a separation optical element having a predetermined width (the width of wavelengths λ1 to λ2) in which the transmittance changes according to the change in wavelength.

[0044] Returning to Fig. 3(a), the first image sensor 52 captures the light reflected by the LRG filter 51 and outputs a reflected image to the computer 70. The second image sensor 53 captures the light transmitted through the LRG filter 51 and outputs a transmitted image to the computer 70. Thus, a detection signal (a signal indicated by the reflected image) representing the amount of reflected light detected by the first image sensor 52 is output to the computer 70, and a detection signal (a signal indicated by the transmitted image) representing the amount of transmitted light detected by the second image sensor 53 is output to the computer 70. Such reflected and transmitted images are spatial distribution data of intensity information and wavelength information of the light collected by the condensing optical system 30. The sum of the amount of reflected light and the amount of transmitted light corresponds to the total amount of measurement light. Note that each of the first image sensor 52 and the second image sensor 53 may be a camera, an area image sensor such as a CCD or a CMOS, a line sensor, or a TDI (Time Delay Integration) sensor. Also, a point sensor may be used instead of the image sensor. Further, instead of the first image sensor 52 and the second image sensor 53, a single image sensor may be used, and an image sensor in which the light receiving portion of the single image sensor is divided may be used.

[0045] The intensity / wavelength information acquisition unit 50 may have the configuration shown in Figure 3(b). In this case, the intensity / wavelength information acquisition unit 50 includes an LRG filter 51 that is movably provided in a direction intersecting the optical axis, and a second image sensor 53 that captures light transmitted through the LRG filter 51 and outputs the transmitted image to the computer 70. The LRG filter 51 is configured to be able to move in and out of the optical path by operating in a direction intersecting the optical axis. The second image sensor 53 detects light through the LRG filter 51 (in this case, transmitted light) when the LRG filter 51 is positioned on the optical path, while detecting light without going through the LRG filter 51 when the LRG filter 51 is not positioned on the optical path. The amount of light detected by the second image sensor 53 when the LRG filter 51 is positioned on the optical path corresponds to the amount of transmitted light. The amount of light detected by the second image sensor 53 when the LRG filter 51 is not positioned on the optical path corresponds to the total amount of measured light. If the total amount of light measured and the amount of transmitted light are known, the amount of reflected light can be derived.

[0046] The intensity / wavelength information acquisition unit 50 may have the configuration shown in Figure 3(c). In this case, the intensity / wavelength information acquisition unit 50 is configured to split the light using a beam splitter 55 and to include an LRG filter 51 placed on the reflected light path of the beam splitter 55. For example, the first image sensor 52 detects the light that has passed through the LRG filter 51. The second image sensor 53 detects the light without going through the LRG filter 51. The amount of light detected by the first image sensor 52 via the LRG filter 51 corresponds to the amount of transmitted light. The amount of light detected by the second image sensor 53 without going through the LRG filter 51 corresponds to the total amount of measured light. If the total amount of measured light and the amount of transmitted light are known, the amount of reflected light can be derived. Based on the amount of light detected in each of the above-described embodiments and the characteristics of the LRG filter 51, the centroid wavelength of the wavelength spectrum of the measured light is derived.

[0047] Physically, the computer 70 is configured to include a memory such as a RAM and a ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The computer 70 functions by executing a program stored in the memory with the CPU. The computer 70 may be composed of a microcomputer or an FPGA.

[0048] Based on the spatial distribution data (for example, the reflected image and the transmitted image obtained in the configuration shown in FIG. 3(a)), the computer 70 derives the centroid wavelength of the light output from the PIC 100. The computer 70 derives the transmission intensity (transmission light amount), which is the intensity of the light transmitted through the LRG filter 51 based on the transmitted image, and derives the reflection intensity (reflection light amount), which is the intensity of the light reflected by the LRG filter 51 based on the reflected image. The computer 70 derives the centroid wavelength based on the transmission light amount and the reflection light amount. The computer 70 derives the difference value between the transmission light amount and the reflection light amount, and derives the centroid wavelength based on the difference value. The transmission intensity (transmission light amount) may be the integrated value of the intensities of the regions of the image in the transmitted image. Also, the transmission intensity (transmission light amount) may be the intensity of each pixel constituting the region of the image in the transmitted image. Further, the reflection intensity (reflection light amount) may be the integrated value of the intensities of the regions of the image in the reflected image. Also, the reflection intensity (reflection light amount) may be the intensity of each pixel constituting the region of the image in the reflected image. Hereinafter, an example of the calculation principle of the centroid wavelength will be described in detail with reference to FIG. 4.

[0049] As described above, the LRG filter 51 reflects all light at wavelengths lower than λ1 and transmits all light at wavelengths higher than λ2, and the transmittance of light changes linearly with wavelength in the wavelength band from λ1 to λ2. In this case, the transmittance h(λ) in relation to wavelengths λ1 and λ2 is given by equation (1) below, and the reflectance 1-h(λ) is given by equation (2) below. h(λ)=(λ-λ1) / (λ2-λ1) (1) 1-h(λ)=(λ2-λ) / (λ2-λ1) (2)

[0050] Furthermore, it is clear that the wavelength λ50% at which the reflectance is 50% (the amount of transmitted light equals the amount of reflected light) is given by the following equation (3): λ50% = (λ2 + λ1) / 2 (3)

[0051] If a spectrum f(λ) is shown by waveform X2 in Figure 4, and lies between λ1 and λ2, and wavelengths shorter than λ1 and longer than λ2 are negligible, then assuming that the amount of reflected light and the amount of transmitted light are equal, the following equation (4) holds: ∫f(λ)h(λ)dλ=∫f(λ)(1-h(λ))dλ (4) Rearranging equation (4), we get the following equation (5): 2∫f(λ)h(λ)dλ=∫f(λ)dλ (5)

[0052] Substituting equation (1) into equation (5), we get 2∫f(λ)(λ-λ1) / (λ2-λ1)dλ=∫f(λ)dλ. Dividing both sides by 2∫f(λ)dλ / (λ2-λ1), we get ∫f(λ)(λ-λ1)dλ / ∫f(λ)dλ= (λ2-λ1) / 2 ∫f(λ)λdλ / ∫f(λ)dλ= (λ2+λ1) / 2 (6).

[0053] Considering equation (3), it is clear that the right-hand side of equation (6) is λ50%, and the left-hand side is generally the centroid of the arbitrary function f(λ). Let this left-hand side of equation (6) be λf. From the above, for any spectrum that passes through a dichroic mirror whose transmittance is linearly sloped with respect to wavelength, if the transmitted light amount and the reflected light amount are equal, the centroid of the spectrum λf is given by λ50%.

[0054] Next, let's consider the second spectrum g(λ). The spectrum of g(λ) is also entirely contained between λ1 and λ2. Now, we calculate the difference between the normalized differences in transmitted and reflected light for spectra f(λ) and g(λ). Let Tf be the transmitted light of f(λ), Rf be the reflected light, Af be the total light intensity, and Df be the difference between transmitted and reflected light. Similarly, let Tg be the transmitted light of g(λ), Rg be the reflected light, Ag be the total light intensity, and Dg be the difference between transmitted and reflected light. Let λg be the centroid of g(λ). In this case, Tf, Rf, Tg, and Rg are measured values, while Af, Ag, Df, and Dg are values ​​that can be directly calculated from the measured values. Each of these values ​​can also be expressed by the following equations.Tf=∫f(λ)h(λ)dλ=∫f(λ)(λ-λ1) / (λ2-λ1)dλ (7) Tg=∫g(λ)h(λ)dλ=∫g(λ)(λ-λ1) / (λ2-λ1)dλ (8) Rf=∫f(λ)(1-h(λ))dλ=∫f(λ)(λ2-λ) / (λ2-λ1)dλ (9) Rg=∫g(λ)(1-h(λ))dλ=∫g(λ)(λ2-λ) / (λ2-λ1)dλ (10) Af=∫f(λ)dλ (11) Ag=∫g(λ)dλ (12) Df=Tf-Rf =2 / (λ2-λ1)*∫λf(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫f(λ)dλ (13) Dg=Tg-Rg =2 / (λ2-λ1)*∫λg(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫g(λ)dλ (14).

[0055] ここで. 10 fを2 f 010 It's a nice place to stay and it's one of the (15) parts. R=Dg / Ag-Df / Af ={∫g(λ)λdλ / ∫g(λ)dλ-∫f(λ)λdλ / ∫f(λ)dλ}*2 / (λ2-λ1) =2(λg-λf) / (λ2-λ1) (15)

[0056] If δλ is the difference between the centroid wavelength λf of spectrum f(λ) and the centroid wavelength λg of spectrum g(λ), then equations (16) and (17) below hold: R = 2δλ / (λ2 - λ1) (16) δλ = R(λ2 - λ1) / 2 (17) As shown above, it has been demonstrated that the difference in the centroids of two arbitrary spectra f(λ) and g(λ) can be obtained from calculations that take into account the amount of transmitted and reflected light.

[0057] Furthermore, when the centroid of f(λ) is λ50%, the amount of reflected light and the amount of transmitted light are equal, so Df becomes 0. In other words, the centroid wavelength λg of any spectrum g(λ) is given by the following equation (18): λg = δλ + λ50% (18)

[0058] As described above, the centroid wavelength of the spectrum can be calculated from the design value of the LRG filter 51, the transmitted light amount, and the reflected light amount. Then, in the inspection device 1, the PIC 100 is inspected using the centroid wavelength as described above.

[0059] The computer 70 generates an inspection image based on spatial distribution data (for example, reflected and transmitted images acquired in the configuration shown in Figure 3(a)) and CAD data stored in the storage unit 80. The storage unit 80 stores CAD data, which is the design information of the PIC 100 to be inspected. In the CAD data, for example, the position, shape, and size of various components, the width, film thickness, and material of the waveguides 108 and 109 are defined as design information.

[0060] The intensity / wavelength information acquisition unit 50 generates a spatial distribution image of intensity information and wavelength information (e.g., derived centroid wavelength) based on spatial distribution data. Figure 5 is a diagram illustrating the display of intensity information and wavelength information. For example, as shown in Figure 5(a), the intensity / wavelength information acquisition unit 50 may express the magnitude of the intensity information with contrast and the difference in wavelength information (centroid wavelength) with a difference in color, and generate a spatial distribution image (map of intensity information and wavelength information) that expresses the intensity information and wavelength information of each pixel, as shown in Figure 5(b). The spatial distribution image is an intensity distribution image and a wavelength distribution image of the light focused by the focusing optical system 30. The computer 70 may then generate an inspection image 500 by superimposing CAD data onto the spatial distribution image, as shown in Figure 5(c). In the example of the inspection image 500 shown in Figure 5(c), for example, the regions of the two waveguides 301 and 302 are indicated in the CAD data, so the CAD data is superimposed on the spatial distribution image, and the positions of regions 201 and 202 corresponding to the two waveguides are clearly indicated. As a result, even when region 202 is not clearly indicated (difficult to clearly distinguish from the other regions) among the regions 201 and 202 corresponding to the two waveguides, as shown in Figure 5(b), it is possible to clearly indicate that region 202 is the region corresponding to the waveguide by superimposing it with the CAD data, as shown in Figure 5(c).

[0061] The computer 70 may set the analysis area in the spatial distribution image based on the CAD data. Figure 6 is a diagram illustrating analysis using CAD data. As shown in Figure 6(a), suppose that multiple leaked light Ll are observed in the waveguide region 201. In such a case, when the computer 70 analyzes the spatial distribution image, it is possible to determine the position of the waveguide based on the CAD data. Therefore, as shown in Figure 6(b), the computer 70 may set the analysis range AR to be calculated based on the CAD data. In the example shown in Figure 6(b), the region including the waveguide region 201 is set as the analysis range AR based on the CAD data. This makes it possible to efficiently perform analysis while ensuring that the range that needs to be analyzed is set as the analysis range AR. For example, if there is a place within the analysis range AR that is in the waveguide region but differs from the waveguide and centroid wavelength, the computer 70 may determine that the place is abnormal and record its CAD coordinates. Waveguide size is very close to the wavelength, and its dimensional accuracy greatly affects the wavelength transmission characteristics. Due to the influence of dimensional accuracy, loss and scattering of incident light can occur on the waveguide, and this light may leak out of the waveguide. By measuring the wavelength information of this leaked light, meaningful data can be obtained compared to measuring only the scattering intensity. By performing wavelength measurements of scattered light, it is possible to evaluate whether wavelength-dependent phenomena are occurring in areas where wavelength dependence was not anticipated in the design (i.e., whether the actual product has been manufactured according to the design).

[0062] The computer 70 may acquire design information for a specific location in the spatial distribution image based on the CAD data. For example, as shown in Figure 6(a), when leak light Ll is observed in a waveguide, the design information in the CAD data can be confirmed for the observation location (specific location) of the leak light Ll. Based on the design information (waveguide width, thickness, shape, upper and lower layer conditions, etc.), it is possible to identify what factors are causing the leak light Ll.

[0063] Furthermore, the computer 70 may further set the acquisition range in which the intensity / wavelength information acquisition unit 50 acquires spatial distribution data based on the CAD data. In this case, the intensity / wavelength information acquisition unit 50 acquires spatial distribution data (intensity information and wavelength information for each pixel) within the acquisition range set by the computer 70. The computer 70 may, for example, identify locations where light leakage is likely to occur particularly strongly based on the CAD data, specifically, parts of the waveguide with a tight radius, parts with rough side walls, parts entering different structures, etc., and set these locations as the acquisition range.

[0064] Figure 7 is a diagram illustrating a modified example of the intensity / wavelength information acquisition unit 50A. The intensity / wavelength information acquisition unit is not limited to the above-described embodiment and may be the intensity / wavelength information acquisition unit 50A shown in Figure 7. The intensity / wavelength information acquisition unit 50A is composed of a condensing lens 56 (condensing optical system), a Fabry-Perot interference filter 57, an imaging lens 58, and an image sensor 59. The condensing lens 56 includes at least one lens and condenses the measurement light and guides it to the Fabry-Perot interference filter 57. The Fabry-Perot interference filter 57 has a mirror section consisting of a pair of mirrors facing each other in the optical axis direction. The distance between the mirror sections is variable. The wavelength of light transmitted through the Fabry-Perot interference filter 57 depends on the distance between the pair of mirrors that make up the mirror section. Therefore, the wavelength of light transmitted through the Fabry-Perot interference filter 57 can be changed by electrically adjusting the distance between the pair of mirrors. In the intensity / wavelength information acquisition unit 50A, the computer 70 controls the Fabry-Perot interference filter 57 so that light of a predetermined wavelength is transmitted between the wavelength bands of the measurement light. By sequentially changing the selected wavelength, a spatial distribution image can be acquired for each selected wavelength within the wavelength bands of the measurement light. The selected wavelength may be set, for example, in increments of 1 nm.

[0065] The imaging lens 58 includes at least one lens and images the measurement light transmitted through the Fabry-Perot interference filter 57 onto the light-receiving section of the image sensor 59. The image sensor 59 is, for example, a CCD image sensor, a CMOS image sensor, etc. The image sensor 59 may also be capable of detecting light in the infrared wavelength range and may be an area image sensor made of Si, InGaAs, InSb, InAsSb, etc. The image sensor 59 captures the measurement light transmitted through the Fabry-Perot interference filter 57 and imaged by the imaging lens 58, and outputs a spatial distribution image at the selected wavelength.

[0066] In this way, the intensity / wavelength information acquisition unit 50A acquires wavelength-specific intensity distribution images 701 (inspection images; multispectral images), which are spatial distribution images of light focused by the focusing lens 56 for each wavelength, for the selected wavelengths (see Figure 8, left). Then, the computer 70 generates wavelength spectral distribution data based on the multiple (selected) wavelength-specific intensity distribution images 701. Wavelength spectral distribution data is wavelength spectral data obtained for each pixel by plotting the intensity of the pixel at the same position (coordinate) against the wavelength. Note that wavelength spectral distribution data may also be created for each ROI by setting a region of interest (ROI) in an arbitrary area of ​​the wavelength-specific intensity distribution image 701 and plotting the intensity (average intensity, etc.) within the set ROI against the wavelength. Wavelength spectral distribution data is an image in which the wavelength spectrum is shown, with wavelength on the horizontal axis and intensity on the vertical axis, as shown in Figure 8, right, for example. The computer 70 may identify the cause of the abnormality in the PIC 100 based on the shape of the wavelength spectrum in the wavelength spectral distribution data. For example, if the shape of the wavelength spectrum is Gaussian (not random) and wavelength-dependent and differs from the normal spectrum of the measured light, the computer 70 may identify that some kind of anomaly has occurred and identify the cause of the anomaly according to the shape of the wavelength spectrum. Furthermore, the computer 70 may detect (identify) an anomaly where the propagation mode of an optical waveguide is unintentionally multimode by measuring the spectral shape of the guided or scattered light in an optical waveguide designed for single-mode propagation. If the computer 70 identifies an anomaly, it may associate and record the CAD coordinate position with the spectral data. The computer 70 may also create wavelength spectral distribution data by overlaying the same position (coordinate) pixels of the wavelength-specific intensity distribution image 701 and changing the display color for each wavelength.

[0067] Figure 9 is a schematic diagram showing an inspection device 1B according to a modified example. The inspection device 1B may also include an intensity / wavelength information acquisition unit 50B that switches between using an intensity / wavelength information acquisition unit 50 (first acquisition unit) and an intensity / wavelength information acquisition unit 50A (second acquisition unit). In this case, the intensity / wavelength information acquisition unit 50B includes an intensity / wavelength information acquisition unit 50, an intensity / wavelength information acquisition unit 50A, and a switching unit 151. As described above, the intensity / wavelength information acquisition unit 50 acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of focused light, based on spatial distribution data. As described above, the intensity / wavelength information acquisition unit 50A acquires wavelength-specific intensity distribution images, which are spatial distribution images for each wavelength of focused light, based on spatial distribution data. The switching unit 151 switches between acquiring the intensity distribution image and centroid wavelength distribution image by the intensity / wavelength information acquisition unit 50 and acquiring the wavelength-specific intensity distribution image by the intensity / wavelength information acquisition unit 50A, according to the control of the computer 70. The switching unit 151 may be a stage or a cylinder that performs the above switching. In this way, by switching between the intensity / wavelength information acquisition unit 50 and the intensity / wavelength information acquisition unit 50A, for example, when checking whether there are any abnormal areas in the waveguide, the acquisition results obtained by the intensity / wavelength information acquisition unit 50, which can be obtained relatively quickly, can be considered, and if there are abnormal areas, the acquisition results obtained by the intensity / wavelength information acquisition unit 50A, which is suitable for identifying the cause of the abnormality, can be considered, making it possible to change the acquisition means according to the purpose. When using the intensity / wavelength information acquisition unit 50, only the centroid wavelength of the measured light can be obtained as wavelength information, but because the amount of data to be handled is small, rapid processing is possible. On the other hand, when using the intensity / wavelength information acquisition unit 50A, the wavelength information becomes the wavelength spectrum, and although the amount of data to be handled is large, a more detailed analysis of the relevant area can be performed. For this reason, after observing the entire PIC 100 with the intensity / wavelength information acquisition unit 50, the area to be analyzed in detail can be narrowed down using CAD data, and then analysis using the intensity / wavelength information acquisition unit 50A can be performed only on the narrowed-down area.

[0068] Next, the processing flow of the inspection method performed by the inspection device will be explained with reference to Figures 10 to 16. First, the basic processing flow of the inspection method will be explained with reference to Figure 10, and then, the more specific processing flow of the inspection method will be explained with reference to Figures 11 to 16.

[0069] In the example shown in Figure 10, a focusing optical system 30, positioned opposite the XY stage 10 on which the actual sample (PIC 100) is placed, focuses the light emitted from the actual sample (PIC 100) (focusing step; step S01). Then, the intensity and wavelength information spatial distribution data of the light focused by the focusing optical system 30 is acquired by the intensity and wavelength information acquisition unit 50 (intensity and wavelength information acquisition step; step S02). Furthermore, an inspection image is generated based on the spatial distribution data acquired by the intensity and wavelength information acquisition unit 50 and the CAD data, which is the design information of the actual sample (PIC 100), stored in the storage unit 80 (analysis step; step S03).

[0070] In the example shown in Figure 11, first, the actual sample (PIC100) is aligned with the CAD data (Step S1). This alignment may be performed, for example, by adjusting the alignment in three places. Next, the measurement target area is measured and a spatial distribution image (inspection image) is acquired (Step S2). Finally, the image size of the spatial distribution image is adjusted to match the CAD data, and the CAD data and the spatial distribution image are superimposed on each other (Step S3).

[0071] In the example shown in Figure 12, first, the actual sample (PIC100) is aligned with the CAD data (step S11). Alignment may be performed by, for example, adjusting the alignment in three places. Next, the acquisition range of the inspection image is set based on the CAD data (step S12). The acquisition range may be, for example, a waveguide with a tight radius, or a point in the waveguide where the width changes. Next, the observation field of view including the set acquisition range is set (step S13), and measurements are taken under the set conditions to acquire a spatial distribution image (inspection image) (step S14). Finally, the image size of the spatial distribution image is adjusted to match the set field of view, and the CAD data and the spatial distribution image are superimposed on each other (step S15).

[0072] In the example shown in Figure 13, first, the actual sample (PIC100) is aligned with the CAD data (step S21). Alignment may be performed, for example, by adjusting the alignment in about three places. Next, the measurement target area is measured and a spatial distribution image (inspection image) is acquired (step S22). Then, the image size of the spatial distribution image is adjusted to match the CAD data, and the CAD data and the spatial distribution image are superimposed on each other (step S23). Finally, from the acquired image, the analysis area (the area analyzed by the computer 70) is set based on the design information of the superimposed CAD data (step S24).

[0073] In the example shown in Figure 14, first, the actual sample (PIC100) is aligned with the CAD data (step S31). This alignment may be performed, for example, by adjusting the alignment in three places. Next, the measurement target area is measured and a spatial distribution image (inspection image) is acquired (step S32). Then, the image size of the spatial distribution image is adjusted to match the CAD data, and the CAD data and spatial distribution image are superimposed on each other (step S33). Finally, the design information of the superimposed CAD data for the measured position is confirmed (step S34).

[0074] The inspection method shown in Figure 15 is performed by an inspection device having an intensity / wavelength information acquisition unit 50A (second acquisition unit). In the example shown in Figure 14, first, the actual sample (PIC 100) is aligned with the CAD data (step S41). Alignment may be performed, for example, by performing alignment adjustments in about three places. Next, the measurement target area is measured and a spatial distribution image (inspection image) is acquired (step S42). Next, the image size of the spatial distribution image is adjusted to match the CAD data, and the CAD data and the spatial distribution image are superimposed on each other (step S43). Next, the wavelength range for acquiring wavelength-specific intensity distribution images and the wavelength step (selected wavelength interval) are set by the intensity / wavelength information acquisition unit 50A (second acquisition unit) (step S44). Then, observation by the intensity / wavelength information acquisition unit 50A is started for the set analysis area (step S45), and it is determined whether or not the specified wavelength range is exceeded when the specified wavelength is changed in the specified step (step S46). If the value does not exceed the specified wavelength range, the measurement of the specified wavelength range is considered incomplete, the specified wavelength is changed, and the process is executed again. If the value does exceed the specified wavelength range, the measurement of the specified wavelength range is considered complete, data acquisition for the specified wavelength range is completed, and a wavelength spectral distribution image is generated based on the wavelength-specific intensity distribution image for each specified wavelength (step S47).

[0075] The inspection method shown in Figure 16 is performed by an inspection device 1B equipped with an intensity / wavelength information acquisition unit 50B that switches between an intensity / wavelength information acquisition unit 50 (first acquisition unit) and an intensity / wavelength information acquisition unit 50A (second acquisition unit). In the example shown in Figure 15, first, the actual sample (PIC 100) is aligned with the CAD data (step S51). Alignment may be performed, for example, by performing alignment adjustments at about three locations. Next, the intensity / wavelength information acquisition unit 50 (first acquisition unit) measures the measurement target area and acquires a spatial distribution image (inspection image) (step S52). Next, the image size of the spatial distribution image is adjusted to match the CAD data, and the CAD data and the spatial distribution image are superimposed on each other (step S53). Next, it is determined whether the wavelength of the incident light (measurement light) and the wavelength observed by the intensity / wavelength information acquisition unit 50 (for example, the centroid wavelength) match (whether the wavelength ranges match) (step S54). In this case, the centroid wavelength range that is determined to be a match may be specified. If the wavelength ranges match, the process is completed.

[0076] On the other hand, if the wavelength ranges do not match, the PIC100 is considered to be in an abnormal state, and in order to estimate the cause of the abnormality, the wavelength range for which the intensity distribution image for each wavelength is acquired by the intensity / wavelength information acquisition unit 50A (second acquisition unit) and the wavelength step (selected wavelength interval) are set (step S55). Then, observation by the intensity / wavelength information acquisition unit 50A is started for the set analysis area (step S56), and when the measurement of the specified wavelength range is completed, a wavelength spectral distribution image is generated (step S57). Finally, it is determined whether it is possible to estimate the cause of the abnormality from the wavelength spectral distribution image (spectral data) (step S58), and if it is possible to estimate it, the process ends, and if it is not possible to estimate it, the process of step S55 is executed again.

[0077] Next, the effects and benefits of the inspection apparatus and inspection method according to this embodiment will be described.

[0078] The inspection device 1 is an inspection device for inspecting a PIC 100, and comprises an XY stage 10 on which the PIC 100 is placed, a focusing optical system 30 positioned opposite the XY stage 10 and for focusing the light output from the PIC 100, an intensity / wavelength information acquisition unit 50 for acquiring spatial distribution data of intensity information and wavelength information of the light focused by the focusing optical system 30, a storage unit 80 for storing CAD data which is the design information of the PIC 100, and a computer 70 for generating an inspection image based on the spatial distribution data and CAD data.

[0079] In the inspection apparatus 1 according to this embodiment, spatial distribution data of light intensity information and wavelength information output from the PIC 100 and focused by the focusing optical system 30 is acquired, and an inspection image is generated based on this spatial distribution data and CAD data, which is the design information of the PIC 100. In this way, by generating an inspection image from spatial distribution data of light intensity information and wavelength information, it is possible to generate an inspection image that appropriately considers the light information. Furthermore, in the inspection apparatus 1 according to this embodiment, since the inspection image is generated by considering CAD data, which is the design information of the PIC 100, in addition to the spatial distribution data, it is possible to generate an inspection image by accurately identifying the spatial location of defects, etc., which are difficult to grasp from light information (intensity information and wavelength information) alone, using the CAD data, which is the design information. This improves the inspection accuracy of the PIC 100. As described above, the inspection apparatus 1 according to this embodiment can appropriately inspect the PIC 100.

[0080] In the inspection device 1, the computer 70 may generate an inspection image by superimposing CAD data onto a spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data. By superimposing CAD data onto the spatial distribution image in this way, it becomes possible to appropriately determine, for example, which structure in the PIC 100 is responsible for the observed leaked light. This improves the inspection accuracy of the PIC 100.

[0081] In the inspection device 1, the computer 70 may further set the acquisition range in which spatial distribution data is acquired by the intensity / wavelength information acquisition unit 50 based on CAD data, and the intensity / wavelength information acquisition unit 50 may acquire spatial distribution data within the acquisition range set by the computer 70. In this way, by setting the acquisition range of spatial distribution data based on CAD data, it becomes possible to acquire spatial distribution data specifically in areas where leakage light is likely to occur (for example, areas with a tight radius in the waveguide, areas with rough side walls, areas entering different structures, etc.), thereby improving inspection efficiency.

[0082] In the inspection device 1, the computer 70 may set an analysis area in the spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data. By limiting the analysis area based on CAD data in this way, it becomes possible to generate inspection images specifically for areas where light leakage is likely to occur, for example, thereby improving inspection efficiency.

[0083] In the inspection device 1, the computer 70 may acquire design information for a specific location in the spatial distribution image of at least one of the intensity information and wavelength information based on spatial distribution data, based on CAD data. With such a configuration, for example, it becomes possible to identify the cause of the leaking light by checking the design information of the location where the leaking light is occurring (waveguide width, thickness, shape, upper and lower layer conditions, etc.).

[0084] In the inspection device 1, the intensity and wavelength information acquisition unit 50 may acquire an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by the focusing optical system 30, based on spatial distribution data. With such a configuration, based on the intensity distribution image and centroid wavelength distribution image, which can be acquired relatively quickly, it is possible to identify, for example, a location in the waveguide where the optical information differs from that of other parts as an abnormal location.

[0085] The intensity / wavelength information acquisition unit 50A may acquire a wavelength-specific intensity distribution image, which is a spatial distribution image of each wavelength of light focused by the focusing optical system, based on the spatial distribution data. By acquiring a wavelength-specific intensity distribution image in this way, it becomes possible to generate a wavelength spectral distribution image, which will be described later, and to identify the wavelength dependence of the intensity distribution.

[0086] The computer 70 may generate a wavelength spectral distribution image, which is an inspection image, based on the wavelength-specific intensity distribution image. By generating a wavelength spectral distribution image, it is possible to determine whether the intensity distribution is wavelength-dependent or not, and for example, the cause of leaked light can be identified with high accuracy.

[0087] The computer 70 may also identify the cause of the anomaly in the PIC 100 based on the shape of the wavelength spectrum in the wavelength spectrum distribution image. From the shape of the wavelength spectrum, for example, the wavelength dependence of leaked light can be identified with high accuracy. By considering this wavelength dependence of leaked light, the cause of the anomaly in the PIC 100 can be identified with high accuracy.

[0088] In the inspection device 1B, the intensity / wavelength information acquisition unit 50B may include: an intensity / wavelength information acquisition unit 50 that acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by a focusing optical system, based on spatial distribution data; an intensity / wavelength information acquisition unit 50A that acquires wavelength-specific intensity distribution images, which are spatial distribution images of light focused by a focusing optical system for each wavelength, based on spatial distribution data; and a switching unit 151 that switches between acquiring the intensity distribution image and centroid wavelength distribution image by the intensity / wavelength information acquisition unit 50 and acquiring the wavelength-specific intensity distribution image by the intensity / wavelength information acquisition unit 50A. In this way, by switching between the intensity / wavelength information acquisition unit 50 and the intensity / wavelength information acquisition unit 50A, for example, when checking whether there are any abnormalities in the waveguide, the acquisition results obtained by the intensity / wavelength information acquisition unit 50, which can be obtained relatively quickly, can be considered, and when abnormalities are found, the acquisition results obtained by the intensity / wavelength information acquisition unit 50A, which is suitable for identifying the cause of the abnormality, can be considered, making it possible to change the acquisition means according to the purpose and inspect the PIC 100 more appropriately.

[0089] 1, 1B... Inspection device, 10... XY stage (stage), 30... Focusing optical system, 50... Wavelength information acquisition unit (first acquisition unit), 50A... Wavelength information acquisition unit (second acquisition unit), 50B... Wavelength information acquisition unit, 56... Focusing lens (focusing optical system), 70... Computer (analysis unit), 80... Memory unit, 100... Photonic integrated circuit (PIC), 151... Switching unit, 500... Inspection image, 701... Wavelength-specific intensity distribution image.

Claims

1. An inspection apparatus for inspecting a photonic integrated circuit, comprising: a stage on which the photonic integrated circuit is placed; a focusing optical system arranged opposite to the stage and for focusing light output from the photonic integrated circuit; an intensity / wavelength information acquisition unit for acquiring spatial distribution data of intensity information and wavelength information of the light focused by the focusing optical system; a storage unit for storing CAD data which is design information of the photonic integrated circuit; and an analysis unit for generating an inspection image based on the spatial distribution data and the CAD data.

2. The inspection apparatus according to claim 1, wherein the analysis unit generates the inspection image by superimposing the CAD data onto a spatial distribution image of at least one of the intensity information and the wavelength information based on the spatial distribution data.

3. The inspection apparatus according to claim 1 or 2, wherein the analysis unit further sets an acquisition range in which the intensity / wavelength information acquisition unit acquires the spatial distribution data based on the CAD data, and the intensity / wavelength information acquisition unit acquires the spatial distribution data within the acquisition range set by the analysis unit.

4. The inspection apparatus according to any one of claims 1 to 3, wherein the analysis unit sets an analysis region in the spatial distribution image of at least one of the intensity information and the wavelength information based on the spatial distribution data, based on the CAD data.

5. The inspection apparatus according to any one of claims 1 to 4, wherein the analysis unit acquires design information for a specific position in a spatial distribution image of at least one of the intensity information and the wavelength information based on the spatial distribution data, based on the CAD data.

6. The inspection apparatus according to any one of claims 1 to 5, wherein the intensity and wavelength information acquisition unit acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by the focusing optical system, based on the spatial distribution data.

7. The inspection apparatus according to any one of claims 1 to 6, wherein the intensity and wavelength information acquisition unit acquires a wavelength-specific intensity distribution image, which is a spatial distribution image for each wavelength of light collected by the focusing optical system, based on the spatial distribution data.

8. The inspection apparatus according to claim 7, wherein the analysis unit generates a wavelength spectral distribution image, which is the inspection image, based on the wavelength-specific intensity distribution image.

9. The inspection apparatus according to claim 8, wherein the analysis unit identifies the cause of an anomaly in the photonic integrated circuit based on the shape of the wavelength spectrum in the wavelength spectral distribution image.

10. The inspection apparatus according to any one of claims 1 to 9, wherein the intensity and wavelength information acquisition unit comprises: a first acquisition unit that acquires an intensity distribution image and a centroid wavelength distribution image, which are spatial distribution images of light focused by the focusing optical system, based on the spatial distribution data; a second acquisition unit that acquires wavelength-specific intensity distribution images, which are spatial distribution images for each wavelength of light focused by the focusing optical system, based on the spatial distribution data; and a switching unit that switches between the acquisition of the intensity distribution image and the centroid wavelength distribution image by the first acquisition unit and the acquisition of the wavelength-specific intensity distribution image by the second acquisition unit.

11. An inspection method for inspecting a photonic integrated circuit, comprising: a focusing step of focusing light output from the photonic integrated circuit using a focusing optical system arranged opposite to a stage on which the photonic integrated circuit is mounted; an intensity / wavelength information acquisition step of acquiring spatial distribution data of intensity information and wavelength information of the light focused by the focusing optical system; and an analysis step of generating an inspection image based on the spatial distribution data and CAD data, which is design information of the photonic integrated circuit stored in a memory unit.

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