Detector, measurement device, and charged particle beam device

Abstract

The detector is provided with: a light-emitting element that emits light by a light beam irradiated to the sample and by collision of quantum emitted from the sample; and a plurality of light-receiving elements that receive light generated by the light-emitting elements through light-receiving surfaces. The light-receiving surface is disposed at a position farther from the light beam than the light-emitting element in a first direction intersecting with an irradiation direction of the light beam, and the light-receiving surface is disposed in a direction intersecting with the irradiation direction of the light beam, and the detector forms: a first optical path for guiding light in the first direction; and a second optical path that guides the light coming through the first optical path toward the light receiving surface.

Description

Technical Field

[0001] The present invention relates to a detector, a measuring device and a charged particle beam device. Background Art

[0002] Detectors convert particle beams such as electrons and ions, and radiation such as X-rays and gamma rays, into electrical signals. When detecting charged particles, they are called charged particle detectors, while when detecting radiation, they are called radiation detectors.

[0003] For example, in charged particle devices such as scanning electron microscopes (SEMs), which utilize charged particle beams, electrons and other charged particles are the primary signal detected. These devices are equipped with a charged particle detector to detect these particles. The SEM irradiates the sample to be observed with an electron beam generated by an electron source, and the detector detects the electrons emitted from the sample. The charged particle detector outputs an electrical signal corresponding to the amount of electrons detected. The SEM image is formed by two-dimensionally displaying the relationship between this electrical signal and the position of the electron beam irradiation on the sample.

[0004] These charged particle detectors are often composed of a light-emitting element that converts detected electrons into photons, a light-receiving element that detects the photons from the light-emitting element and converts them into electrical signals, and a light guide that transmits the light emitted by the light-emitting element to the light-receiving element. Photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) are used for the light-receiving element. Alternatively, by changing the type of light-emitting element in the same structure, a radiation detector can be formed. Specifically, a radiation detector uses a light-emitting element that converts detected radiation into light of a wavelength detectable by the light-receiving element, and transmits the light from the light-emitting element to the light-receiving element via a light guide.

[0005] In recent years, detectors have been required to perform at various levels. For example, to improve the signal-to-noise ratio (SNR) of SEM images, it has become important to have detectors that do not saturate their output signals when the electron beam irradiation dose is increased. Patent Document 1 proposes a detector comprising a scintillator, a light guide, and a photodetector, wherein the photodetector has a larger detection surface area than the scintillator, in order to obtain an observation image with accurate contrast without saturation.

[0006] Furthermore, Patent Document 2 proposes a charged particle beam device, the purpose of which is to widely cover the detection angle range of charged particles emitted from a sample.

[0007] Patent Document 3 proposes a charged particle beam device using a light guide capable of increasing the ratio of light emitted by a light emitting element reaching a light receiving element, that is, light utilization efficiency.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: International Publication No. 2021 / 176513

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-37226

[0012] Patent Document 3: International Publication No. 2020 / 059114 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] When an electron beam irradiates a sample, signal electrons are emitted radially from an irradiation area (called an observation point) that is tens of μm wide. To efficiently capture these signal electrons, it is preferable to configure the light-emitting element to be isotropic, such as a ring. If the light-emitting element is configured as a ring, the light-emitting element's emission surface also becomes a ring.

[0015] On the other hand, the light-receiving surface of a light-receiving element, which receives light, is generally a quadrilateral. Therefore, in order to efficiently capture signal electrons and convert them into signals via the light-receiving element, a light guide is required to illuminate the quadrilateral light-receiving surface with light emitted from the annular light-emitting element's emission surface. While a light-receiving surface that is sufficiently large relative to the light-emitting element's emission surface and sufficiently separated from the light-receiving surface and the light-emitting element may increase the size of the structure, it is possible to create a light guide connecting the two.

[0016] However, as detectors become larger, their placement within the SEM becomes limited. In particular, detectors placed near the sample to obtain more signal require thin and compact detectors, which are incompatible with the larger light guide structure described above. Consequently, efficient detection of radially emitted signal electrons is not possible.

[0017] Therefore, an object of the present invention is to provide a detector structure that is thin and surrounds an observation point with a light-emitting element, efficiently captures signal electrons, and allows the emitted light to reach a light-receiving element with low loss.

[0018] Patent Documents 1 and 2 do not mention light propagation loss caused by the difference in shape between the light-emitting and light-receiving surfaces as a problem. Because this is not considered a problem, there is no description of a method for optically coupling a ring-shaped light-emitting element to a quadrilateral light-receiving element.

[0019] Patent Document 3 does not describe a light guide or detector that efficiently combines the emission surface of a ring-shaped light emitting element with a quadrilateral light receiving surface. Furthermore, although a charged particle detector is described, the aforementioned problem also arises when the signal is not electrons but radiation.

[0020] Another problem is that the output signal of the detector is saturated when the current of the electron beam irradiating the sample is increased.

[0021] When the electron beam dose is increased, the number of signal electrons emitted from the sample and detected by the detector increases, improving the S / N ratio of the SEM image. Therefore, it is necessary to increase the electron beam dose (increase the current). At this time, the energy of the signal electrons is converted into photons by the light-emitting element, and the number of photons incident on the light-receiving element also increases.

[0022] However, if the incident photon density increases relative to the area of ​​the detection surface, the photodetector becomes saturated and cannot accurately output an electrical signal proportional to the number of incident photons. For example, a SiPM (e.g., manufactured by Hamamatsu Photonics Co., Ltd., model number: S13360-3050VE) has a detection surface that is 3 mm square and is covered with tiny square detection pixels, each approximately 50 μm on a side. When a photon strikes each detection pixel, a current pulse signal is generated for each pixel, and the current pulse signal for each pixel represents the detection of a single photon. However, if the incident photon density increases and multiple photons strike the same detection pixel simultaneously, the proportional relationship between the number of incident photons and the output current is disrupted, making it impossible to obtain an accurate SEM image.

[0023] This is a problem of saturation of the light receiving element caused by increasing the electron beam current. Patent Documents 2 and 3 do not describe these problems.

[0024] Let's further explain the issue. Signal electrons fly from the observation point toward the detector, but the signal electrons' impact on the light-emitting element is concentrated on the surface of the light-emitting element near the observation point. Especially in detectors located near the sample, the light-emitting element cannot be enlarged, so the area where the signal electrons are incident becomes smaller, increasing the incidence density. Therefore, when using high currents, the large number of photons generated from the tiny area of ​​the light-emitting element, i.e., the high photon density, can lead to saturation of the light-receiving element, a significant issue.

[0025] Patent Documents 1 to 3 do not describe the problem of signal saturation caused by high-density light emission from this microscopic region and its countermeasures. This problem is not limited to charged particle detectors but also applies to radiation detectors where the radiation generation and detection locations are close.

[0026] In order to arrange the detector near the observation point and surround the observation point to efficiently detect signal electrons, the detector structure that optically and efficiently couples the thin and annular light-emitting surface with the quadrilateral light-receiving surface, and the structure that suppresses signal saturation are also important separately. However, by taking further considerations, the observation and measurement accuracy of measuring devices such as SEM is greatly improved.

[0027] In view of the above situation, the purpose of the present invention is to provide a detector, a measuring device and a charged particle beam device that can efficiently detect signal electrons emitted from an observation point, and can output electrical signals without saturation even if the signal electrons and radiation dose incident on the detector increase.

[0028] Means for solving problems

[0029] An example of a detector of the present invention includes:

[0030] a light emitting element that emits light by irradiating the sample with a light beam and colliding with quanta emitted from the sample; and

[0031] a plurality of light receiving elements, which receive the light generated by the light emitting element through a light receiving surface;

[0032] In a first direction intersecting the irradiation direction of the light beam, the light receiving surface is arranged at a position farther from the light beam than the light emitting element.

[0033] The light receiving surface is arranged in a direction intersecting with the irradiation direction of the light beam.

[0034] The detector forms:

[0035] a first light path directing light toward the first direction; and

[0036] A second optical path guides the light arriving via the first optical path toward the light receiving surface.

[0037] An example of a detector of the present invention includes:

[0038] a light emitting element that emits light by irradiating the sample with a light beam and colliding with quanta emitted from the sample; and

[0039] a plurality of light receiving elements, which receive the light generated by the light emitting element through a light receiving surface;

[0040] In a first direction intersecting the irradiation direction of the light beam, the light receiving surface is arranged at a position farther from the light beam than the light emitting element.

[0041] The detector has a transparent area that transmits light quantum incident from the light emitting element toward the light receiving surface.

[0042] The normal line of the light receiving surface forms an angle of less than 45 degrees with the first direction.

[0043] An example of the measuring device of the present invention includes the above-mentioned detector.

[0044] An example of the charged particle beam device of the present invention includes the above-mentioned detector.

[0045] Effects of the Invention

[0046] According to the present disclosure, a detector, a measuring device, and a charged particle beam device can be provided that have high detection efficiency and can output electrical signals without saturation even when the amount of signal electrons or radiation incident on the detector increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic diagram of SEM.

[0048] Figure 2A It is a perspective view showing a configuration example of the detector 5 according to the first embodiment.

[0049] Figure 2B 1 and 2 are a bottom view and a cross-sectional view showing a configuration example of the detector 5 according to the first embodiment.

[0050] Figure 3A This is a perspective view of the light emitting element 10 of Example 1.

[0051] Figure 3B This is an enlarged view of the vicinity of the position where the signal electron 102 is incident.

[0052] Figure 3C It is the result of ray tracing simulation.

[0053] Figure 3D It is the relationship between the incident angle to the light-emitting element and the amount of signal electrons absorbed in the light-emitting element without being released.

[0054] Figure 4A This is a perspective view of the light guide 11 of Example 1.

[0055] Figure 4B is the light guide 11 of embodiment 1 and Figure 4A Stereoscopic images in different directions.

[0056] Figure 5 This is a detailed diagram of the light receiving element 12 of Example 1.

[0057] Figure 6A It is a perspective view showing a structural example of the detector 5 of the second embodiment.

[0058] Figure 6B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of the second embodiment.

[0059] Figure 7A It is a perspective view showing a structural example of the detector 5 of the third embodiment.

[0060] Figure 7B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of the third embodiment.

[0061] Figure 8A It is a perspective view showing a structural example of the detector 5 of the fourth embodiment.

[0062] Figure 8B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of the fourth embodiment.

[0063] Figure 8C yes Figure 8B (b) A partial enlarged view.

[0064] Figure 9A It is a perspective view showing a structural example of the detector 5 of the fifth embodiment.

[0065] Figure 9B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of the fifth embodiment.

[0066] Figure 9C This is the relationship between the light guide 11 and the light emitting element 10 in Example 5.

[0067] Figure 10A It is a perspective view showing a structural example of the detector 5 of the sixth embodiment.

[0068] Figure 10B It is a bottom view showing a structural example of the detector 5 of Example 6.

[0069] Figure 11A It is a perspective view showing a structural example of the detector 5 of Example 7.

[0070] Figure 11B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of Example 7.

[0071] Figure 11C yes Figure 11B (b) A partial enlarged view.

[0072] Figure 12A It is a perspective view illustrating the three-dimensional structure of the detection element group 5g of Example 7.

[0073] Figure 12B It is a bottom view illustrating the three-dimensional structure of the detection element group 5g of Example 7.

[0074] Figure 12C It is a bottom view showing a structural example of the detector 5 according to a modified example of the seventh embodiment.

[0075] Figure 12D It is a top view showing a structural example of the detector 5 according to a modified example of the seventh embodiment.

[0076] Figure 12E It is a perspective view illustrating the three-dimensional structure of a detection element group 5g according to a modified example of the seventh embodiment.

[0077] Figure 13A This is an example of the shape of the light emitting element 10 of Example 7.

[0078] Figure 13B This is an example of a shape obtained by deforming the shape of the light emitting element 10 of Example 7.

[0079] Figure 14A It is a perspective view showing a structural example of the detector 5 of Example 8.

[0080] Figure 14B It is a bottom view and a cross-sectional view showing a structural example of the detector 5 of Example 8.

[0081] Figure 14C yes Figure 14B (b) A partial enlarged view.

[0082] Figure 14D This is a perspective view of the detection element group 5g of Example 8.

[0083] Figure 14E This is an example of the structure of a light-emitting element using powder.

[0084] Figure 14F This is another structural example of a light-emitting element using powder.

[0085] Figure 14G It is a cross-sectional view near the incident surface 10i of a modification of Example 8.

[0086] Figure 15A This is a diagram showing a detection element group 5g of Example 9.

[0087] Figure 15B This is a structural example for using one of the detection elements in Example 9 to produce a first image whose main signal source is X-rays, and using the other detection elements to produce a second image whose main signal source is electrons.

[0088] Figure 15C This is a structural example in which the cross-sectional shape of the light guide 11 in Example 9 is curved.

[0089] Figure 15D This is a variation of Example 1.

[0090] Figure 15E This is a variation of Example 2.

[0091] Figure 16A It is a part of the detector of Example 10.

[0092] Figure 16B is the voltage signal Sv generated by the detection circuit 15 of the tenth embodiment.

[0093] Figure 16C This is an example of the GUI of the tenth embodiment.

[0094] Figure 17 It is an existing detector. DETAILED DESCRIPTION

[0095] Particles such as electrons and ions, photons, and radiation (high-energy photons) such as X-rays and gamma rays are collectively referred to as quanta. In this specification, the beam of particles such as electrons and ions, and the beam of quanta such as X-rays and gamma rays irradiating a sample are simply referred to as beams, or, for ease of understanding, the irradiated quanta are identified and referred to as electron beams, etc. When a beam strikes a sample, some quanta are emitted from the sample, depending on the energy and type of the beam and the type of sample. A light-emitting element (generally called a scintillator) is an element that emits light in response to the incident quanta.

[0096] [Example 1]

[0097] The following describes embodiments of the present disclosure based on the accompanying drawings. An electron microscope using an electron beam, particularly a scanning electron microscope (SEM), is described below as an example of a charged particle beam device, but the present invention is not limited thereto. For example, charged particle beam devices also include scanning ion microscopes using ion beams. Furthermore, the present invention can also be applied to semiconductor pattern measurement devices, inspection devices, and observation devices using scanning electron microscopes.

[0098] In addition, the embodiments of the present disclosure are not limited to the embodiments described below, and various modifications can be made within the scope of the technical concept. In addition, corresponding parts of the various figures used in the description of the embodiments described below are sometimes marked with the same reference numerals, and repeated descriptions are sometimes omitted.

[0099] Figure 1 This is a schematic diagram of a SEM as a charged particle beam device. The SEM functions as a measurement device. Figure 1 As shown, the charged particle beam device 1 includes a scanning deflector 3 and an objective lens 4 , which are arranged on the trajectory of an electron beam 101 (generally referred to as primary electrons in SEM) drawn from an electron source 2 .

[0100] The electron beam 101 irradiates the sample 7 arranged on the sample transport table 6, and signal electrons 102 are emitted from the sample 7. Here, the signal electrons 102 refer to electrons emitted from the sample, such as secondary electrons directly excited by the electron beam 101 and released into the vacuum, and reflected electrons that are repeatedly scattered in the sample by the electron beam 101 and released into the vacuum again. Generally, reflected electrons are defined as signal electrons above 50eV. In addition, when the electron beam 101 is irradiated, sometimes not only signal electrons 102 but also X-rays are generated. In this embodiment, the signal electrons 102 are used as the quanta incident on the detector for explanation, but it is not limited to this. There are also cases where the signal is X-rays.

[0101] Below the objective lens 4 is a detector 5 for detecting signal electrons 102. An opening is provided in the center of the detector 5 for passing the electron beam 101. The electron beam 101 emitted from the electron source 2 is controlled by the objective lens 4 and focused on the specimen 7 to minimize its beam diameter. The scanning deflector 3 is controlled by the system control unit 8 so that the electron beam 101 scans a predetermined area of ​​the specimen 7.

[0102] Signal electrons 102 generated at the position where electron beam 101 reaches sample 7 are detected by detector 5. Detected signal electrons 102 are processed synchronously with a scanning signal sent from system control unit 8 to scanning deflector 3, forming a SEM image on monitor 9.

[0103] Figure 2A as well as Figure 2B It is a diagram showing a configuration example of the detector 5 . Figure 2A It's a stereogram. Figure 2B (a) is a bottom view of the detector 5 as viewed from the sample 7 side. Figure 2B (b) Yes Figure 2B (a) Cross-sectional view along line AA.

[0104] In the description of this embodiment, the direction away from the central axis C of the electron optical system of the charged particle beam device (radial direction) is used. For example, Figure 2B The x-axis direction in (a) is referred to as the outside or the outside direction, and conversely, the direction toward the center axis C is referred to as the inside or the inside direction.

[0105] The detector 5 is composed of a light emitting element 10 , a light guide 11 , a light receiving element 12 , and a mounting substrate 13 on which the light receiving element 12 is mounted. Figure 2B (a) The portion of the light receiving element 12 that is blocked by the light guide 11 and cannot be seen is also indicated by a dotted line.

[0106] In addition, Figure 2B In (a), the outer shape of the light emitting element 10 is indicated by a bold line. Figure 3A A perspective view of the light emitting element 10 is shown. Figure 4Aand 4B is a perspective view of the light guide 11 . Figure 5 A diagram showing details of the light receiving element 12 .

[0107] This embodiment describes the use of a SiPM, one of the smallest light-receiving elements with a gain of 10⁶. However, the light-receiving element is not limited to this. Various light-receiving elements can be used, such as a PMT (for example, a micro PMT, which is a small PMT), an avalanche photodiode, and a PIN photodiode.

[0108] To allow the electron beam 101 to pass through, the center of the detector 5 forms an opening 14 , and a hole is formed in the mounting substrate 13 to form a region without components such as the light emitting element 10 . The electron beam 101 passes through the opening 14 and enters the sample 7 .

[0109] use Figure 2B (b) The photon from the irradiation electron beam 101 to the received signal electron 102 is described. Figure 2B (b) shows the sample 7, the electron beam 101, the signal electron 102, and the light rays Ray1 and Ray2 generated by the light emitting element.

[0110] The signal electron 102 is emitted from the observation point MP where the electron beam 101 is incident on the sample 7. Since the electron beam 101 is scanned, strictly speaking, the observation point MP moves within a certain range, but this range is sufficiently small compared to the size of the detector, so in the description of this embodiment, Figure 2B As shown in (b), the point where the central axis C and the sample 7 intersect is set.

[0111] The angle (polar angle θo) between the direction of flight of the signal electron 102 and the central axis C is considered to be the same as the angle at which the signal electron 102 was emitted from the observation point MP, as reflected electrons with high energy. Hereinafter, the angle from the central axis C is referred to as the polar angle, and the angle within a plane perpendicular to the central axis C is referred to as the azimuth angle φ. The reference for the azimuth angle is appropriately determined as needed.

[0112] Most of the signal electrons 102 emitted from the sample 7 are incident on the incident surface 10i of the light-emitting element. Depending on the energy of the electrons, they penetrate tens of nanometers to tens of micrometers inward from the incident surface 10i and lose energy. On the other hand, the light-emitting element 10, having gained energy, emits light. Therefore, the light-emitting region is a thin shell-like region of about tens of micrometers from the incident surface 10i. If the higher-energy signal electrons 102 generated by increasing the current of the electron beam 101 or raising the voltage for accelerating the electron beam are incident on the incident surface 10i, a large number of photons are generated from this thin shell-like region.

[0113] In this way, the light-emitting element 10 emits light by irradiating the sample 7 with a light beam (in this embodiment, it is an electron beam 101, but not limited to this) and colliding with quanta emitted from the sample 7 (in this embodiment, it is a signal electron 102, but it can also be other particle beams or radiation. The same is true in other embodiments).

[0114] Here, use Figure 17 The example of the conventional detector shown here illustrates the problems caused by a large number of photons generated from a tiny area.

[0115] In the case of a detector placed between the sample 7 and the objective lens of the SEM, in order to obtain sufficient performance by the resolution of the SEM, the space from the mounting substrate 13 to the sample 7 is about 5 mm. Therefore, there is almost no room for the light guide to enter, such as Figure 17 As shown, a light receiving element 12 is arranged on the mounting substrate, and a light emitting element 10 is arranged facing the light receiving element 12. In this case, the distance between the observation point MP and the innermost light emitting element 10n is about 1 to 3 mm.

[0116] On the other hand, although SiPM is small, it is only approximately 3 mm in size. Therefore, most of the signal electrons 102 are concentrated on the light-emitting element 10n closest to the electron beam 101, causing the light-receiving element 12n to saturate. In this structure, when the light-receiving element is a SiPM, saturation occurs even with electron beam currents of tens of picoamps. Meanwhile, obtaining a SEM image with a sufficient S / N ratio depends on sample 7. However, for example, in semiconductor circuit patterns with three-dimensional structures such as trenches, currents exceeding several nanoamps are required.

[0117] In this embodiment, in order to solve this problem, Figures 2A to 5 The illustrated structure guides most of the light generated at incident surface 10i in a first direction intersecting the irradiation direction of electron beam 101. The optical system comprising light-emitting element 10 and light guide 11 propagates the light in the first direction, thereby diffusing the light and reducing the photon density. The first direction is, for example, generally radially outward from electron beam 101 and may also include a component in the axial direction of electron beam 101 (either in the same direction as or opposite to the direction of travel of electron beam 101). The optical path of the light guided in the first direction is referred to as the first optical path.

[0118] Where the light diffuses to a certain extent, a second optical path that guides the light from the first optical path toward the light receiving surface of the light receiving element continues, and the light reaches the light receiving element. In this way, the detector 5 forms a first optical path and a second optical path. The first optical path is an optical path that guides the light in the first direction, and the second optical path is an optical path that guides the light arriving via the first optical path toward the light receiving surface 12i of the light receiving element 12 (see Figure 2B (a) Guided light path.

[0119] like Figure 2B As shown in Figure 1(a), the light-receiving element 12 includes a light-receiving surface 12i, which receives light generated by the light-emitting element 10. In this embodiment, by arranging the light-receiving surface 12i farther from the electron beam 101 than the light-emitting element 10, the electron beam 101 can be surrounded by multiple light-receiving elements 12, allowing the reception of diffused light. This structure prevents signal saturation in the light-receiving elements 12.

[0120] In this embodiment, the light receiving element 12 may be a silicon photomultiplier tube, so that the saturation of the signal can be suppressed according to the characteristics of the silicon photomultiplier tube.

[0121] In addition, the position where the light-receiving surface is farther away from the electron beam than the light-emitting element, for example, in a certain definition example, refers to a structure in which the distance between the portion of the light-receiving surface closest to the electron beam and the electron beam is greater than the distance between the portion of the light-emitting element closest to the electron beam and the electron beam. In addition, in another definition example, refers to a structure in which the distance between the portion of the light-receiving surface farthest from the electron beam and the electron beam is greater than the distance between the portion of the light-emitting element farthest from the electron beam and the electron beam. A definition combining the conditions of these two definitions can also be used. Figure 2B In (b), all parts of the light-receiving surface 12 i are located farther from the electron beam 101 than all parts of the light-emitting element 10 .

[0122] In this embodiment, the light-receiving surface 12i is arranged to be oriented orthogonal to the irradiation direction of the electron beam 101 (i.e., the normal to the light-receiving surface 12i is parallel to the irradiation direction of the electron beam 101). Consequently, the detector 5 can be configured to be thin (i.e., its axial dimension can be reduced). Furthermore, the light-receiving surface 12i is not limited to being oriented strictly orthogonal to the irradiation direction of the electron beam 101; as long as the light-receiving surface 12i is oriented so as to intersect the irradiation direction of the electron beam 101, the axial dimension of the detector 5 can be reduced to a degree corresponding to that orientation.

[0123] Furthermore, the emission surface 10 o of the light emitting element 10 is bonded to the incident surface 11 i of the light guide, and the emission surface 11 o of the light guide 11 is bonded to the light receiving surface 12 i of the light receiving element 12 .

[0124] The light emitting element 10, the light guide 11 and the light receiving element 12 are mounted on the same mounting substrate 13. Figure 2B As shown in FIG. 2( b ), by configuring the light guide 11 to form a first optical path and a second optical path, light can be transmitted from the light-emitting element 10 mounted on the same substrate to the light-receiving element 12. Mounting the light-emitting element 10 and the light-receiving element 12 on the same substrate allows the length of the light guide 11 to be shortened compared to mounting them on separate substrates, resulting in a structure that achieves high light utilization efficiency.

[0125] like Figure 2B As shown in FIG. 1( b ), the length of the light guide 11 in the first direction in a cross-section including the central axis C can be shorter than the width of the two light-receiving elements 12. By reducing the size of the light guide 11, the detector 5 can be reduced in size overall, allowing it to be placed in a variety of locations, thus expanding its applicability. Furthermore, while the light-emitting element 10 and light guide 11 are secured by adhesive bonding, the securing method is not limited to this. They can also be covered with a thin cover, mechanically secured to the mounting substrate 13 using screws, or a combination of adhesive bonding and mechanical fixing can also be used.

[0126] exist Figure 2B In (a), the arrangement of the light-receiving elements 12 surrounding the electron beam 101 is preferably circular (e.g., the vertices of a regular polygon), since this allows for uniform light reception. Furthermore, a circular arrangement allows for high-density arrangement of light-receiving elements, thus also accommodating increased currents. Furthermore, it allows for efficient reception of propagating light without omission, thereby also improving light utilization efficiency. However, a circular arrangement is not necessarily required; various arrangements are possible, such as a quadrilateral or an ellipse with randomly spaced light-receiving elements 12. The present invention is not limited to this arrangement method for the light-receiving elements 12.

[0127] In addition, Figure 2B In the example (b), the first direction can be defined as a direction perpendicular to electron beam 101, for example, the direction of arrow D1. In this example, the direction is perpendicular, but sometimes, due to installation reasons within the SEM, mounting substrate 13 is tilted or electron beam 101 is tilted to align with the measurement object, and the first direction can be set appropriately. It is important to diffuse the light in a direction that is not parallel to electron beam 101 (a direction that intersects electron beam 101).

[0128] An example of a structure that directs light in a first direction is Figure 2B In the cross section (b) including the central axis C, the light-emitting element 10 and the light guide 11 are arranged in the first direction, and the optical path formed by these components is the first optical path. Furthermore, by making the incident surface 10i of the light-emitting element a spherical surface, it becomes a surface that reflects and guides a portion of the light isotropically emitted from the light-emitting element in the first direction.

[0129] exist Figure 2B In (b), the second optical path is the radially outer portion of the light guide, that is, the triangular area where the reflective surface 11r is located. This is the area indicated by arrow D2. From the point where the reflective surface 11r, which is inclined relative to the first direction, begins, the amount of light directed toward the light-receiving surface 12i increases sharply radially outward. Therefore, the optical path starting from the point where the reflective surface 11r begins can be referred to as the second optical path. Similarly, when the first and second optical paths are formed by curved surfaces, the point where the amount of light directed toward the light-receiving surface 12i begins to increase, or the point where the surface's inclination relative to the first optical path becomes greater, can be defined as the second optical path.

[0130] Furthermore, the boundary between the first and second optical paths may or may not be clearly defined. The downstream portion of the first optical path and the upstream portion of the second optical path may overlap, or other optical paths may be formed between these optical paths. For example, the portion of the optical path immediately after light is generated in the light-emitting element 10 may be considered the first optical path, while the portion of the optical path immediately before light is incident on the light-receiving surface 12i of the light-receiving element 12 may be considered the second optical path.

[0131] The following details are provided using light rays Ray 1 and Ray 2. Both emit light and begin propagation at the point of incidence of signal electron 102. Ray 1 is not reflected by reflective surface 11r, but propagates along the first optical path and then along the second optical path before entering the light-receiving element. The light-receiving surface 12i is connected to the light guide's exit surface 11o via an adhesive, so Ray 1 is not reflected by exit surface 11o and enters the light-receiving surface 12i via the adhesive.

[0132] In particular, the light ray Ray 1 is reflected twice in the first optical path. Thus, the first optical path is formed to include a surface that performs the following reflections.

[0133] - A surface that reflects light having a component in the first direction and a component in the direction opposite to the irradiation direction of the electron beam (upward component in the figure) in a direction having a component in the first direction and a component in the irradiation direction of the electron beam (downward component in the figure) (initial reflection)

[0134] - A surface that reflects light having a component in the first direction and a component in the irradiation direction of the electron beam (downward component in the figure) in a direction having a component in the first direction and a component in the direction opposite to the irradiation direction of the electron beam (upward component in the figure) (second reflection)

[0135] By configuring the first optical path to include at least one of these surfaces, light can be propagated in the first direction.

[0136] Light ray Ray2 travels approximately straight in the first direction, is reflected by reflective surface 11r within the second optical path, and is incident on the light-receiving element. For example, reflective surface 11r reflects light arriving in a direction perpendicular to the electron beam's irradiation direction (light ray Ray2 generally arrives in this direction) toward a component with an opposite direction (upward component in the figure) to the electron beam's irradiation direction. This configuration allows light traveling in the first direction to be guided toward light-receiving surface 12i.

[0137] Reflection at the vacuum interface between the light-emitting element 10 and the light guide 11 is assumed to be total internal reflection. Therefore, light that does not meet the conditions for total internal reflection is emitted into the vacuum and is lost. To reduce this loss, a reflective material such as an aluminum film can be formed on the surfaces of these components. Furthermore, if there is no adhesive between the light-receiving surface 12i and the light guide's exit surface 11o, and the light guide interface is air, the probability of reflection at the exit surface 11o due to total internal reflection or Fresnel reflection increases.

[0138] For example, light ray Ray 1 and the like have a high probability of being reflected due to their large angle of incidence on the emission surface 11o. This means that the light reflected from the emission surface 11o may be repeatedly reflected between the reflection surface 11r and the light receiving surface 12i, or may be emitted from the reflection surface 11r to the outside of the detector or lost as stray light. Therefore, it is preferable to provide an adhesive between the light receiving surface 12i and the emission surface 11o of the light guide.

[0139] exist Figure 2B In (a), the spread of light in the direction of azimuth angle φ is described using light rays Ray 1 to Ray 4. For convenience, the circumferential position of the point where the signal electron 102 is incident is used as a reference for azimuth angle φ, and is defined as the x-axis. Figure 2B The light ray Ray1 and the light ray Ray2 in (a) are examples of light rays with an azimuth angle φ of zero, and are examples of light rays incident on the light receiving element 12 closest to the point where the signal electron 102 is incident.

[0140] The light emission in the azimuth direction is also isotropic, so the light also propagates in the direction with a large azimuth angle, such as the light ray Ray 3 and the light ray Ray 4. By propagating in various azimuth directions in this way, the light is diffused.

[0141] As described above, when light-receiving elements 12 are arranged to surround electron beam 101, as in this embodiment, it is also possible to receive light that has diffused in the azimuth direction. Specifically, light-emitting elements 10 are arranged at the center, surrounding the central axis, and light-receiving elements 12 are arranged on the periphery, surrounding the central axis. This configuration, which propagates light in a first direction and then in a second direction, diffuses light emitted from a small area near the center in the azimuth direction, reducing the photon density. The light is then received by multiple light-receiving elements 12 surrounding the periphery, thereby reducing the amount of light entering a single light-receiving element and suppressing saturation. By increasing the circumference of light-receiving elements 12 in proportion to the amount of electron beam 101, a detector can be provided that does not saturate even when the signal electrons 102 increase.

[0142] The above is an overview of this embodiment. Hereinafter, each component will be described in detail.

[0143] The light emitting element 10 of this embodiment is a crystal light emitting element whose shape is changed by cutting or the like. Examples of light emitting element materials include YAP (YAlO3: Ce), YSO (Y2SiO5: Ce), YAG (Y3Al5O 12 :Ce), GGAG((Y,Gd)3(Al,Ga)5O 12 :Ce,(Y,Gd)3(Al,Ga)5O 12 :Tb), GOS (Gd2O2S:Pr, Gd2O2S:Ce, Gd2O2S:Tb), etc. Furthermore, the crystal may be single crystal, polycrystalline, or sintered ceramic. However, the present invention is not limited to the material of the light-emitting element.

[0144] like Figure 2B (b) and Figure 3A As shown, the incident surface 10i is shaped as a sphere centered at the observation point MP. This is done so that the surface normal faces the observation point MP. This structure has two advantages. One is that it reflects light emitted from the spherical surface toward the first direction, as described above. The other is that it absorbs as much energy as possible from the incident signal electrons, thereby increasing the amount of light emitted. These will be explained in turn.

[0145] Regarding reflection in the first direction, the incident surface 10i can be effectively reflected as long as it is inclined relative to the first direction. For the sake of simplicity, a case where the incident surface 10i is inclined at a certain angle relative to the first direction is considered.

[0146] Figure 3B The diagram shows an enlarged view of the vicinity of the incident position of the signal electrons 102. The incident surface 10i is inclined at an inclination angle θis. The diagram describes an example in which the signal electrons 102 penetrate into the light emitting element 10 by a maximum of several tens of μm while being scattered.

[0147] Inside the light emitting element, the energy state is excited by the energy received from the signal electron 102, and light is emitted, releasing energy. The emitted light is emitted isotropically from each light emitting point. Figure 3B As shown by light rays Ray5 and Ray6, a portion of the light emitted from the multiple internal light-emitting points EP propagates toward incident surface 10i, is reflected by the inclined incident surface 10i, and propagates generally in the first direction (the direction of arrow D1). Thus, if incident surface 10i, on which signal electrons 102 are incident in the light-emitting element, is tilted relative to the first direction, the light is reflected in a direction having a component in the first direction.

[0148] exist Figure 3C The results of studying this effect in ray tracing simulations are shown in FIG. Figure 3BIn an optical system in which a light-emitting element 10 having the cross-sectional shape shown and a refractive index of approximately 2.0 and a light guide 11 having a refractive index of approximately 1.5 are connected by an adhesive having a refractive index of approximately 1.5, the propagation efficiency of photons reaching the incident surface of the light guide (the amount of light reaching the incident surface of the light guide / the amount of light emitted) is calculated.

[0149] Figure 3C The vertical axis represents propagation efficiency, and the horizontal axis represents the tilt angle θis. The results show that the maximum light intensity is achieved when the tilt angle θis is around 45 to 50 degrees. Compared to a tilt angle of 0 degrees, a tilt angle of 45 degrees increases the light intensity by approximately 1.6 times. On the other hand, if the tilt angle is less than 15 degrees or greater than 80 degrees, the effect decreases (the improvement rate due to tilt is less than half of the maximum improvement rate). Therefore, from the perspective of propagation efficiency, a tilt angle of 15 degrees or greater and less than 80 degrees is preferred.

[0150] In addition, in this embodiment, the incident surface 10i is tilted relative to the first direction. However, if only the effect of reflection in the first direction is considered, reflection from surfaces other than the incident surface 10i can also be used. For example, even if the incident surface 10i is parallel to the first direction, the same effect can be obtained by tilting the surface opposite to the incident surface 10i in the direction of light beam irradiation (the surface on the opposite side of the incident surface 10i) relative to the first direction. That is, when Figure 3B The same reflection effect can be obtained when the shape of the light emitting element is reversed with respect to the top and bottom (ie with respect to the direction of light beam irradiation) and the lower plane after the inversion is used as the incident surface.

[0151] In Example 8, an example is described in which only the effect of such reflection is considered (see Figure 14G ) In addition, both the incident surface 10i and the surface on the opposite side may be inclined relative to the first direction.

[0152] Next, we'll explain the advantages of fully absorbing the energy of signal electrons and increasing the amount of light emitted. When the incident surface 10i is spherical, the angle (incident angle) at which the signal electron 102 emitted from the observation point MP enters the incident surface 10i is zero, and the amount of light emitted from a single signal electron is maximized. This is primarily due to the fact that as the angle of incidence increases, the signal electrons that once enter the light-emitting element are repeatedly scattered within the element, escaping from the element again into the vacuum. This mechanism is based on experimental findings and electron trajectory simulations.

[0153] Figure 3D The horizontal axis represents the incident angle θi, and the vertical axis represents the relative absorption of signal electrons relative to 0 degrees.

[0154] The incident angle θi is zero and drops sharply when it exceeds a maximum of 30 degrees. That is, when the incident angle θi of the signal electron on the light-emitting element exceeds 30 degrees, the reduction in the amount of light emitted becomes greater. Therefore, by configuring the light-emitting element so that the incident angle θi is less than 30 degrees, the effect of suppressing the reduction in the amount of light emitted is achieved. From this point of view, the incident angle θi of the spherical surface is the smallest and therefore the best shape. In addition, the incident surface 10i with an incident angle θi of less than 30 degrees can be easily designed as a surface inclined relative to the first direction. Therefore, in this embodiment, it is a structure that can obtain dual advantages.

[0155] Here, the reason why the incident surface 10i can be configured as a spherical surface or the like and the incident angle θi can be set to 30 degrees or less is that, as shown in FIG. Figure 2B As shown in (a), light-receiving element 12 is positioned farther from electron beam 101 than light-emitting element 10, and a light guide 11 connects the two. This allows the detection of signal electrons in a small region to be separated from the location where the emitted light is received. In other words, even if the incident surface 10i of the light-emitting element is of a free shape, the light-emitting element 10 and light guide 11 extending in the first direction can eliminate the influence of this shape (the influence of the shape difference with light-receiving surface 12i), allowing the emitted light to be efficiently transmitted to light-receiving surface 12i.

[0156] Next, use Figure 2A 、 Figure 2B 、 Figure 4A as well as Figure 4B The light guide 11 will be described. Figure 4A 4B and 4B are perspective views of the light guide 11 viewed from the sample 7 side and the electron beam irradiated side, respectively, and are views showing the three-dimensional shape. Figure 4A 1 and 2 show a reflection surface 11r and an incident surface 11i facing the emission surface 10o of the light emitting element. Since the emission surface 10o of the light emitting element is cylindrical, the incident surface 11i is also cylindrical.

[0157] exist Figure 4B In the figure, the surface 11rc on the opposite side to the reflecting surface 11r is shown, and the surface facing the light receiving surface 12i of the light receiving element in the surface is the emitting surface 11o (see bottom view). Figure 2B (a)).

[0158] In this embodiment, the light guide 11 is fixed to the mounting substrate 13 by bonding it to the light receiving surface 12i with an adhesive having a refractive index close to that of the material of the light guide 11, and fixed via the light receiving element 12. Mechanical fixing with screws or the like is also possible, but bonding improves light utilization efficiency.

[0159] Light reaching the exit surface 11o is reflected when the angle of incidence on the exit surface is greater than total internal reflection, rather than entering the light-receiving element. This light becomes stray light and is largely lost. When the light guide 11 is made of resin or quartz, the refractive index is approximately 1.5, so light at an incident angle of 42 degrees or greater is totally reflected. However, if an adhesive such as resin or glass with a similar refractive index is used, total internal reflection between the light guide 11 and the adhesive does not occur, and the majority of the light reaching the exit surface 11o is incident on the light-receiving surface 12i. Therefore, the adhesive, with a roughly equal refractive index, serves as a means of extracting light from the light guide 11 to the light-receiving element 12.

[0160] Furthermore, from the perspective of total reflection, the refractive index of the adhesive is preferably greater than or equal to that of the light guide 11 and less than or equal to that of the light-receiving surface. For example, it is preferable to use epoxy resin (refractive index of approximately 1.55) for the light-receiving surface and the adhesive, and acrylic resin (refractive index of approximately 1.49) for the light guide 11, taking into account transparency.

[0161] The light extraction member is preferably made of an adhesive that covers Figure 2B The adhesive is applied to the entire light-receiving surface 12i indicated by the dotted line in (a). By using the adhesive, the transmittance of light emitted to the outside of the light guide is increased only at the emission surface 11o, which is opposite to the light-receiving surface 12i, on the surface 11rc opposite the reflective surface 11r. This increases the amount of light received by the light-receiving surface 12i, and accordingly reduces the amount of light lost in a vacuum by emitting from the surface of the surface 11rc that is not opposite to the light-receiving surface 12i.

[0162] Furthermore, since the transmittance toward the light-receiving surface 12i increases only on the emission surface 11o, the probability that light propagating in the azimuth direction toward a direction other than the light-receiving surface 12i will be repeatedly scattered and incident on the light-receiving surface 12i also increases. In other words, the light utilization efficiency of light emitted in the azimuth direction toward a direction other than the light-receiving surface 12i is also improved.

[0163] However, materials other than adhesives can also be used as light extraction components. A gel-like component can also be sandwiched between the light guide 11 and the light-receiving surface 12i. Even if a light extraction structure is provided in which the emitting surface 11o facing the light-receiving surface 12i is formed into a surface with a microscopic structure such as a rough surface or an uneven surface, this can still improve light utilization efficiency. Light extraction components such as adhesives and light extraction structures can be used in combination.

[0164] On the other hand, the fixing between the light guide 11 and the light emitting element 10 also improves light utilization efficiency for the same reason of suppressing total reflection, so it is preferable to use an adhesive. In other words, the adhesive also serves as a member for guiding light from the light emitting element 10 to the light guide 11 and guiding the light in the first direction.

[0165] The refractive index of the light-emitting element, such as the material of the aforementioned light-emitting element, is generally greater than approximately 2.0. Therefore, the refractive index of the light guide 11, typically made of quartz or resin, is low. Consequently, total internal reflection occurs at the interface between the light-emitting element and the adhesive. This total internal reflection traps the emitted light within the light-emitting element, where it is repeatedly scattered until it is absorbed by the light-emitting element itself or by reflective materials such as aluminum.

[0166] This loss depends on the shape of the light-emitting element and the presence of light extraction components such as adhesives, but it can sometimes result in a loss of 70% to 80% of the emitted light. To extract this trapped light to the outside, the angle of incidence at the interface with the adhesive surface can be kept within the angle of total reflection during repeated scattering.

[0167] The total reflection angle at the interface between a light-emitting element with a refractive index of 2.0 and a vacuum is 30 degrees, whereas the total reflection angle at the interface between a light-emitting element with a refractive index of 1.5 and an adhesive is 48 degrees. Therefore, a certain structure can be used to keep the incident angle on the bonding surface within 48 degrees.

[0168] exist Figure 3B In the cross-sectional shape of the light-emitting element shown, if the incident surface 10i is a quadrilateral with an inclination angle θis of 0 degrees, the incident angle of the totally reflected light remains constant on all four sides, and total reflection is repeated until it is absorbed. However, if the inclination angle θis is not 0 degrees, the incident angle of the light incident on the incident surface 10i and reflected on the next side changes. This change in the incident angle allows the trapped light to enter the interface with the adhesive material, which is most easily emitted, within the total reflection angle, pass through the adhesive, and enter the light guide 11, improving light utilization efficiency.

[0169] That is, the light guide efficiently extracts the confined light that has been repeatedly totally reflected from the light emitting element through the light guide, due to both the fixing of the light emitting element and the tilt of the incident surface 10i of the light emitting element.

[0170] Furthermore, when the incident surface 10i is inclined, a triple effect is achieved by changing the propagation angle of the light rays Ray 5 and Ray 6 and increasing the absorption of the signal electrons 102. This demonstrates that an inclined incident surface 10i produces an appropriate effect.

[0171] use Figure 5 The SiPM as a light-receiving element will be described. Figure 5 (a) is a bottom view of the SiPM viewed from the light receiving surface 12i side. Figure 5 (b) Yes Figure 5 Cross-sectional view along line AA in (a). Figure 5 (c) is a diagram showing an example of a circuit for obtaining a signal from a SiPM.

[0172] The frame 12f is provided with a detection surface 12d that converts light into an electrical signal. A transparent resin or quartz cover is provided to protect the detection surface 12d. In this embodiment, the light receiving surface 12i is a surface of resin or quartz facing the detection surface 12d.

[0173] In the case of SiPM, the dynamic range is maximized when uniform light is irradiated onto the detection surface 12d, thus suppressing saturation. Therefore, as in this embodiment, the light guide's reflective surface 11r reflects light toward the entire light-receiving surface 12i, thereby covering the entire light-receiving surface 12i rather than just partially. This configuration effectively suppresses saturation.

[0174] Furthermore, the SiPM has an anode and a cathode electrode. A high voltage is applied to the cathode electrode, and the current value output from the anode electrode is read as a signal. Other circuit examples are also conceivable, but this circuit example will be used for explanation in this embodiment.

[0175] The presence of multiple SiPMs increases the number of wiring lines. Meanwhile, the voltage applied to the cathode controls the magnitude of the electrical signal output from the SiPM and determines the multiplication factor, which is defined by the number of electrons generated within the SiPM when one photon is detected.

[0176] Typically, the voltage required to achieve the same multiplication factor varies between SiPMs, necessitating individual control. However, by appropriately selecting the individual SiPMs, the voltage required to achieve the same multiplication factor can be reduced to, for example, 0.5 V or less, allowing the operating voltage applied to the electrodes of multiple SiPMs to be the same (e.g., by sharing the wiring). For example, by sharing the voltage applied to all SiPMs, the number of wirings can be halved.

[0177] However, even with the same number of photons, individual screening alone can cause differences in the current output from the SiPM, which can affect the SEM image. This effect can be reduced by adjusting the effect for each SiPM using subsequent circuits or signal processing.

[0178] Figure 5 (c) shows an example circuit. For simplicity, three SiPMs are shown as light-receiving elements 12. As described above, each SiPM has an anode electrode 12AE and a cathode electrode 12CE. Current signals Isig1 to Isig3 are output from each anode electrode 12AE. These signals are preferably read and processed individually. Of course, if the effect is minimal, wiring can be connected and the sum of the currents can be read. Any suitable configuration can be employed.

[0179] A bias voltage Vbias is applied to the cathode electrode 12CE as an operating voltage that determines the multiplication factor. In order to suppress fluctuations in the operating voltage applied to the cathode electrode 12CE, a capacitor 12Cs may be connected to the same mounting substrate 13 .

[0180] exist Figure 5 In (c), the cathode electrodes 12CE of all SiPMs are connected to the wiring that supplies the bias voltage Vbias, thereby sharing the voltage applied to the SiPMs and reducing the number of wiring lines to one. If there are three SiPMs and bias voltage Vbias is supplied individually, a total of three wiring lines would be required for the cathode electrodes 12CE. This allows the voltage applied to the SiPMs to be shared, eliminating two wiring lines. This structure, which reduces the number of wiring lines, reduces the size of the connector, and is ideal for installing detectors in narrow areas, as in this embodiment.

[0181] Furthermore, circuit components such as resistors may be inserted between the cathode electrode 12CE and the wiring supplying the bias voltage Vbias for reasons such as noise suppression. However, as long as the operating voltage is considered to be the same, the voltage range is sufficient. As an example of this range, a range in which the signal output from the anode electrode 12AE can be corrected through signal processing (for example, a range in which saturation is not achieved in subsequent circuits) can be used. The operating voltage applied to the cathode electrode 12CE is preferably within a range of ±10% of the specified voltage. For example, when the specified operating voltage Vbias is 55V, a range of approximately 50-60V is sufficient.

[0182] If this structure is described from another point of view, it can be said that the number of wirings is reduced by providing a structure in which a certain wiring is branched and connected to a plurality of cathode electrodes 12CE in the mounting substrate 13 .

[0183] By arranging the light-receiving surface 12i of the light-receiving element at a position away from the light-emitting element 10 in the first direction relative to the electron beam 101, the positions of the light-emitting element 10 and the light-receiving element 12 are separated in the first direction. This creates a space for light diffusion between the light-emitting element 10 and the light-receiving element 12, thereby increasing the current.

[0184] Furthermore, by separating in the first direction, the light-emitting element 10 can be extended in the first direction. This allows the incident surface 10i and the emission surface 10o to have completely different shapes. As a result, the incident surface 10i can be spherical, effectively detecting signal electrons, while the emission surface 10o can be shaped so that its normal is roughly parallel to the first direction (arrow D1), making it easier to emit light in the first direction. In other words, the separation in the first direction described above achieves the effect of efficiently detecting signal electrons and facilitating the emission of light in the first direction (improving light utilization efficiency).

[0185] Furthermore, after light is propagated in the first direction along the first optical path, the light arriving via the first optical path is then propagated toward the light-receiving surface 12i via a reflective surface or the like. This allows the light to be evenly irradiated onto the light-receiving surface 12i, which has a larger area than the light-emitting surface 10o of the light-emitting element. In other words, the difference in area between the light-emitting surface 10o and the light-receiving surface 12i is eliminated by the second optical path.

[0186] In summary, the light receiving surface 12i of the light receiving element is arranged at a position farther away from the light emitting element 10 in the first direction relative to the electron beam 101, so that the light propagates in the first direction and then propagates in the second optical path toward the light receiving surface 12i through the reflecting surface, etc., thereby achieving the effects of increasing the current of the electron beam 101, efficiently detecting signal electrons, improving light utilization efficiency, and ensuring uniform light incidence on the light receiving surface.

[0187] [Example 2]

[0188] Figure 6A as well as Figure 6B This is a diagram showing a configuration example of the detector 5 according to the second embodiment. Figure 6A Indicates a stereogram. Figure 6B (a) shows a bottom view. Figure 6B (b) indicates Figure 6B (a) Cross-sectional view along line AA. Explanations of the same structures as in Example 1 are omitted. The difference from Example 1 is that the light emitting element 10 serves as the light guide 11.

[0189] Compare Figure 2B (b) and Figure 6B (b) It can be seen that the light emitting element 10 of Example 2 is a combination of the light emitting element 10 of Example 1 and the light guide 11. Figure 2A as well as Figure 2B In the embodiment, the first optical path (the optical path guiding light in the direction of arrow D1) formed by the light emitting element 10 and the light guide 11 is Figure 6A as well as Figure 6B The light emitting element 10 is composed solely of a light emitting element 10. The light emitting element 10 has a second optical path (an optical path that guides light in the direction of arrow D2) formed by a light guide 11. A reflective surface 11r located on the light guide 11 also has the light emitting element 10 as a reflective surface 10r. Furthermore, the emission surface 10o of the light emitting element is fixed to the light receiving element 12 with an adhesive.

[0190] As an advantage of this structure, since there is no light guide 11, there is no bonding process between the light guide and the light emitting element, and the light guide and the light receiving element, so it is easy to assemble. Since one interface is reduced, the reduction in light utilization efficiency caused by interface reflection can be suppressed.

[0191] When the amount of electron beam 101 irradiated on sample 7 is small and the amount of signal electrons 102 is small, the number of light-receiving elements 12 can be reduced, and the radius of arrangement can also be reduced. Therefore, it is sometimes better to use only light-receiving elements 12 rather than sandwiching a light guide in the middle. Whether to use the structure of Example 1 or Example 2 can be selected based on the application product.

[0192] In addition, in Example 2, the effects described in Example 1, such as the effect of improving the light utilization efficiency of the adhesive, can also be obtained in the same manner.

[0193] [Example 3]

[0194] Figure 7A as well as Figure 7B This is a diagram showing a configuration example of the detector 5 according to the third embodiment. Figure 7A Indicates a stereogram. Figure 7B (a) shows a bottom view. Figure 7B (b) indicates Figure 7B (a) Cross-sectional view taken along line AA. Detailed description of the same structures as those in Example 1 will be omitted.

[0195] The difference from the first embodiment is that the emission surface 11o and the reflection surface 11r of the light guide 11 are divided corresponding to the light receiving surface 12i. Figure 2A And the effect described in 2B in Example 1 (the effect of suppressing light emitted from a position different from the emission surface 11o on the surface 11rc opposite to the reflection surface 11r and becoming stray light and being lost).

[0196] use Figure 7B (a) is described below. By dividing the reflective surface 11r corresponding to the light-receiving surface 12i and using the side surfaces of the divided areas as reflective surfaces 11rs, light traveling in the azimuth direction toward an area without light-receiving elements 12, as in the case of light ray 7, is also reflected by the reflective surface 11rs and returned to the area where the light-receiving surface 12i is located. This effectively suppresses light that is emitted from a position different from the emission surface 11o on the surface 11rc opposite the reflective surface 11r and is lost as stray light.

[0197] In addition, the effects described in Example 1, such as the effect of improving the light utilization efficiency of the adhesive, can also be obtained in Example 3. In addition, as shown in Example 2, the light emitting element 10 may also function as the light guide 11.

[0198] [Example 4]

[0199] Figures 8A to 8C This is a diagram showing a configuration example of the detector 5 according to the fourth embodiment. Figure 8A Indicates a stereogram. Figure 8B(a) shows a bottom view. Figure 8B (b) indicates Figure 8B (a) Cross-sectional view along line AA. Figure 8C express Figure 8B (b) A partial enlarged view.

[0200] This example is an example in which the structure of Example 3 is modified, and the description of the same structure as Example 3 is omitted. The difference from Example 3 is that a plurality of light receiving surfaces 12i (12ia, 12ib, 12ic) of the light receiving element are arranged in a manner along a first direction intersecting the irradiation direction of the electron beam 101. Figure 8B (a) is a bottom view of the embodiment of the present invention. Figure 8B In the direction of arrow D1 in (b), the light receiving surfaces 12i of the plurality of light receiving elements 12 (12a, 12b, 12c) are arranged.

[0201] In light-emitting element 10, the point where signal electron 102 enters becomes the luminous point, generating tens to hundreds of photons per signal electron. In the structure of Example 1, these photons can diffuse freely in the azimuth direction. However, in the structure of Example 3, the reflective surface 11rs spatially restricts the photons compared to the structure of Example 1. Therefore, the structure of Example 3 makes it easier for more photons to reach light-receiving element 12 near the luminous point than in the structure of Example 1.

[0202] Therefore, in the fourth embodiment, a structure is provided that can disperse and acquire photons emitted in a specific azimuth direction.

[0203] like Figures 8A to 8C As shown, the light receiving surfaces 12i of the three light receiving elements are arranged along the first direction, and the reflecting surfaces 11r are provided so as to cover them. The light guide's emitting surfaces 11o (11oa, 11ob, 11oc) are respectively opposite the light receiving surfaces 12i and fixed to the opposing light receiving surfaces with an adhesive.

[0204] With this configuration, in Example 3, light is received by one light-receiving element 12 in each direction after division, whereas light is received by three light-receiving elements. Therefore, a simple calculation can reduce the number of photons incident on a single light-receiving surface to one-third. Consequently, this configuration achieves the following effects: photons lost between light-receiving elements 12 and 12 are eliminated, improving light utilization efficiency; and the light-receiving surface 12i is increased, suppressing saturation of the light-receiving element 12.

[0205] Next, the second optical path will be described. Figure 8BIn (b), there are multiple second directions (arrows D2) toward the light-receiving surface. A second optical path is formed at the point where the surface of light guide 11 tilts from the first direction (arrow D1), i.e., in a region radially outward of the radial position where reflective surface 11r begins. Reflective surface 11r begins inward of the innermost light-receiving surface 12ai so that the same amount of light is incident on all light-receiving elements 12.

[0206] In addition, if Figure 8C As shown, light intensity adjusters 11g for adjusting the amount of light incident on the light receiving element are provided before and after the light receiving element 12. The light intensity adjuster 11g of this embodiment comprises a surface 11g1 reflecting light radially inward from the light receiving element and a surface 11g2 reflecting light radially outward.

[0207] Figure 8C Light ray Ray8 is an example of light being reflected by surface 11g1 of light intensity adjustment unit 11g, located between light receiving elements 12a and 12b, and incident on inner light receiving surface 12ia. Light ray Ray9 is an example of light being reflected by surface 11g2 and incident on light receiving surface 12ic. As surfaces 11g1 and 11g2 become perpendicular to emission surface 11o, the amount of reflection increases inward and outward, respectively.

[0208] Furthermore, these surfaces 11g1 and 11g2 are preferably deposited with an aluminum film or the like. Furthermore, if surface 11g2 is parallel to the emission surface 11o and lacks a reflective material such as aluminum, light leakage from this surface will occur. Therefore, tilting surface 11g2 also suppresses light leakage. Thus, light intensity adjustment portion 11g serves to uniformize the amount of light incident on light-receiving element 12 in the first direction. Furthermore, the presence of an aluminum film deposited on surfaces 11g1 and 11g2, and the fact that surface 11g2 is tilted relative to the emission surface, further serve to suppress light leakage between light-receiving elements 12 and improve light utilization efficiency.

[0209] In addition, in this embodiment, the light receiving elements are arranged along the first direction, and the corresponding light guide 11 becomes a straight line when viewed from above. Figure 8B As shown in (a), the width WLGP of the light guide when viewed from the bottom surface is constant from the radial position DP where the light guide starts to be divided in the azimuth direction to the outermost position in the radial direction.

[0210] If there is a portion of the light guide where the width is reduced in the direction of light propagation, the incident angle of light will decrease when reflected by the reflective surface 11rs, destroying the condition for total reflection and causing light to leak from the light guide into the vacuum. To suppress losses caused by this light leakage, the light guide 11 is configured so that its width does not decrease in the first direction from the radial position DP where the division begins.

[0211] In addition, due to the manufacturing reasons of the light guide, the width WLGP may vary by about 0.1-0.5mm along the first direction, but the variation caused by such deviation is considered to be approximately constant. In addition, the width WLGP is gradually reduced in such a way that the inclination of the side surface (reflection surface 11rs) in the azimuth direction is less than 15 degrees when viewed from above. When the radial dimension of the light guide 11 is short, light leakage is reduced. For example, the length of the light guide 11 in the radial direction is as follows: Figure 8B In the case where there are approximately three light-receiving elements as shown in (a), the reduction in width WLGP can also be considered small and substantially constant.

[0212] As described above, the light receiving elements are arranged along the first direction, and the reflecting surface 11rs and the light quantity adjusting portion 11g are provided on the light guide 11 in a manner corresponding to them. The width WLGP does not decrease, thereby suppressing light leakage and improving light utilization efficiency.

[0213] In addition, in this embodiment, the width WLGP of the light guide 11 is approximately the same as the width WRS of the light receiving surface 12i. However, they do not need to be the same. For example, the width WLGP of the light guide 11 may be set to be less than 1 times, less than 1.1 times, less than 1.2 times, less than 1.3 times, less than 1.4 times, or less than 1.5 times the width WRS of the light receiving surface 12i. If it is less than 1.5 times, the above-mentioned effect can be achieved to a substantial extent.

[0214] In Example 4, the effects described in Examples 1 and 3, such as the effect of improving the light utilization efficiency of the adhesive, can also be obtained. In addition, as shown in Example 2, the light emitting element 10 may also function as the light guide 11 .

[0215] [Example 5]

[0216] Figures 9A to 9C This is a diagram showing a structural example of the detector 5 of the fifth embodiment. Figure 9A Indicates a stereogram. Figure 9B (a) shows a bottom view. Figure 9B (b) indicates Figure 9B (a) Cross-sectional view along line AA. Figure 9C 1 and 2 show the relationship between the light guide 11 and the light emitting element 10 .

[0217] This example is an example in which the structure of Example 4 is modified, and the description of the same structure as Example 4 is omitted. The difference from Example 4 is that Figure 9A as well as Figure 9B As shown, the light guide 11 is completely separated in the azimuth direction (circumferential direction). The light guide 11 has an elongated shape (for example, an elongated rectangle) extending in the first direction when viewed from below, which has the advantage of being easy to process.

[0218] In this structure, the incident surface 11i of the light guide, when viewed from above, is set to a straight line perpendicular to the propagation direction (first direction), so that light incident on the light guide 11 is propagated to the outermost light-receiving surface 12ic. This is because, when viewed from above, the light guide has an elongated shape extending in the propagation direction, and the incident surface is perpendicular to the propagation direction, so that light continues to be guided within the light guide to a distant point in the propagation direction.

[0219] In order to face the incident surface of the light guide, the emission surface 10o of the light emitting element 10 is also a straight line when viewed from above. The outer shape of the light emitting element 10 (in Figure 9B Indicated by a bold line in (a). ) is a regular polygon (a regular dodecagon in this example) equal in number to the number of divisions in the azimuthal direction. In a structure where the light guide is completely divided, by making the outer shape of the light-emitting element 10, when viewed from above, a regular polygon equal to the number of divisions, light can be propagated within the light guide.

[0220] In addition, since the difference from Example 4 is the complete separation of the azimuthal direction of the light guide, Figure 9B The cross-sectional shape of the AA line shown in (b) is the same as Figure 8B (b) substantially the same shape.

[0221] In addition, when the outer shape of the light emitting element 10 is a regular polygon when viewed from below, it is preferable to make the width WLGP of the light guide (see FIG. 1 ) smaller than 0.01 in order to prevent the incident surface of the light guide from interfering with each vertex in terms of structure. Figure 9B (a)) is larger than the width WE of the emission surface 10o of the light emitting element (see Figure 9C ) is slightly smaller. In addition, Figure 9C As shown, a protruding portion 10g may be provided so that the emission surface 10o of the light emitting element protrudes radially outward to guide light.

[0222] In this case, by combining the width WE of the emission surface 10o, it is possible to form Figure 9C The regular polygon is shown by the dashed line. In other words, the width WE is the same length as the side of the regular polygon. That is, by setting the outer shape of the light-emitting element 10, when viewed from above, to be based on a number of regular polygons equal to the number of divisions, light can be propagated within the light guide. This shape can be said to be a shape in which rectangles are connected to the outside of each side of the regular polygon. The length of the connected side of the connected rectangle is the same length as one side of the regular polygon.

[0223] Furthermore, when the protruding portion 10g is provided, interference between components is eliminated, so the width WLGP of the light guide can be made larger than the width WE of the light emitting element's emission surface 10o, leaving enough room for all light emitted from the emission surface 10o to enter. This improves light utilization efficiency.

[0224] Furthermore, the structures described in Examples 1, 3, and 4, such as the improvement of light utilization efficiency by the adhesive, can also be appropriately applied to Example 5, and the same effects can be obtained.

[0225] [Example 6]

[0226] Figure 10A as well as Figure 10B This is a diagram showing a configuration example of the detector 5 of the sixth embodiment. Figure 10A Indicates a stereogram. Figure 10B Indicates a bottom view. In addition, relative to Figure 10B The cross-sectional view of line AA is the same as Figure 9B (b) is a cross-sectional view of the same figure.

[0227] This example is an example in which the structure of Example 5 is modified, and the description of the same structure as Example 5 is omitted. The difference from Example 5 is that Figure 10A as well as Figure 10B As shown, the light emitting elements 10 are also completely separated in the azimuth direction (circumferential direction). That is, a plurality of light emitting elements are arranged in the circumferential direction of the electron beam.

[0228] The divided light-emitting element 10, light guide 11, and light-receiving element 12 form a single independent detection element 5e, each functioning as a single detector. Specifically, when signal electrons 102 are incident on light-receiving element 12, the emitted light passes through light guide 11 and reaches light-receiving element 12, which then outputs an electrical signal corresponding to signal electrons 102. The structure of this embodiment is such that twelve detection elements (5e1 to 5e12) are arranged around central axis C. Consequently, each detection element can independently measure signal electrons 102.

[0229] With this configuration, by identifying the detection element that received the signal, it is possible to determine the azimuth angle from which the incoming signal electron was detected. In other words, this configuration not only suppresses signal saturation in light-emitting element 10 but also enables signal discrimination based on azimuth angle. Hereinafter, signal discrimination based on azimuth angle is referred to as azimuth angle discrimination.

[0230] Particularly in semiconductor inspection equipment, the observation of three-dimensional structures has become increasingly important due to the three-dimensional nature of recent semiconductor structures. The human eye perceives objects in three dimensions by observing them from two directions. This structure, by utilizing signals from 12 directions, improves the visibility of three-dimensional structures.

[0231] Furthermore, to achieve azimuth angle discrimination, the light-emitting elements do not necessarily need to be arranged densely and evenly around the circumference of the electron beam, as in this embodiment. Even if there are no light-emitting elements in a certain area along the circumference, azimuth angle discrimination can still be achieved in other directions. In other words, azimuth angle discrimination can be achieved by arranging multiple light-emitting elements around the circumference of the electron beam.

[0232] Furthermore, the structures described in Examples 1 to 5, such as the improvement of light utilization efficiency by the adhesive, can also be appropriately applied to Example 5, and the same effects can be obtained.

[0233] [Example 7]

[0234] Figures 11A to 11C This is a diagram showing a structural example of the detector 5 of the seventh embodiment. Figure 11A Indicates a stereogram. Figure 11B (a) shows a bottom view. Figure 11B (b) indicates Figure 11B (a) Cross-sectional view along line AA. Figure 11C express Figure 11B (b) A partial enlarged view.

[0235] This example is an example in which the structure of Example 6 is modified, and descriptions of the same structures as Example 6 are omitted. The difference from Example 6 is that a plurality of light-emitting elements 10 (10a, 10b, 10c) are arranged in the irradiation direction of the electron beam 101, and a light guide 11 (11a, 11b, 11c) is provided for each light-emitting element 10. Each light guide 11 has a first optical path for guiding light in a first direction and a second optical path for guiding light toward a plurality of light-receiving surfaces 12i (12ia, 12ib, 12ic) arranged along the first direction.

[0236] Light-emitting element 10a, light guide 11a, and light-receiving element 12a together form an independent detection element that functions as a single detector. Specifically, when signal electron 102 is incident on light-receiving element 12a, the emitted light passes through light guide 11a and reaches light-receiving element 12a, which then outputs an electrical signal corresponding to signal electron 102. Similarly, light-emitting element 10b, light guide 11b, and light-receiving element 12b form an independent detection element, while light-emitting element 10c, light guide 11c, and light-receiving element 12c form an independent detection element.

[0237] Each detection element has the features of the detector described in Example 1 and achieves the same effects. Specifically, the detector is configured to detect signal electrons 102 at a tiny incident surface 10i near the center, propagate and diffuse the light emitted therein in a first direction, and receive the light at a light-receiving surface 12i having an area sufficiently larger than that of the incident surface 10i. This configuration allows the detector to maintain signal saturation even when the beam volume increases.

[0238] Figure 11C Light ray Ray10 is shown as an example of light propagating within a detection element. When signal electron 102 is incident on incident surface 10ib of the light-emitting element, the light emitted at this point of incidence propagates in a direction intersecting electron beam 101 (the direction of arrow D1). The light path propagating in this direction can be defined as the first light path. Light guide 11b is bent midway, and the light propagating within it travels toward the corresponding light-receiving surface 12ib. The path from this bend point to the light guide's exit surface 11ob can be defined as the second light path.

[0239] In the detector 5, three types of detection elements are gathered to form a detection element group 5g ( Figure 11C Represents a detection element group 5g), such as Figure 11B As shown in (a), detection element groups (5g1 to 5g12) are arranged to surround the central axis C. Each detection element group 5g is configured to detect signal electrons by dividing the space with multiple detection elements, and can strictly control the amount of light incident on each light-receiving surface 12i (12ia, 12ib, 12ic).

[0240] The amount of light can be controlled by adjusting the size of the incident surfaces (10ia, 10ib, 10ic) of the light-emitting element, thereby adjusting the amount of signal electrons 102 incident on the incident surface 10i. This configuration adjusts the size of the incident surface 10i so that light is uniformly incident on each light-receiving surface 12i. This effectively suppresses saturation of the light-receiving elements 12 within the detector 5 due to an increase in signal intensity.

[0241] This effect is achieved in addition to the saturation suppression effect described in Examples 1 to 6. The structure of Example 6 also suppresses saturation caused by increasing the current, but by using the detection element group 5g as in this example, the additional effect of being able to control the amount of light incident on each light-receiving surface 12i and control the light so that it is incident on the light-receiving surface uniformly is achieved.

[0242] Furthermore, as described in the description of Example 1, the arrangement of the detection elements and detection element group 5g relative to the central axis C is not limited to that shown. They do not necessarily need to completely surround the central axis C and can be arranged in a portion of the circumferential region (this also applies to the aforementioned embodiments). Even a single detection element can provide an effect. That is, the detection element and detection element group 5g have the effect of suppressing saturation caused by large currents simply by themselves.

[0243] Furthermore, by arranging multiple light-emitting elements 10 in the direction of electron beam 101, it is possible to obtain a signal corresponding to each light-emitting element, thereby enabling signal discrimination also in the direction of polar angle θo. Discriminating signals in the direction of polar angles is called polar angle discrimination. Similar to azimuth angle discrimination, polar angle discrimination improves the visibility of three-dimensional structures.

[0244] Furthermore, the direction of emitted signal electrons varies depending on the material and shape of the sample. Even for azimuthally isotropic samples, the polar angle varies. Therefore, by detecting the polar angle of emission of signal electrons from the sample, further information regarding the sample's material and shape can be obtained. The detector of this embodiment, with its aforementioned structure, is capable of calculating the polar angle θo based on information from the incident detection element, effectively obtaining information regarding the sample's material and shape.

[0245] Figure 12A as well as Figure 12B It is a diagram illustrating the three-dimensional structure of the detection element group 5g. Figure 12A It's a stereogram. Figure 12B From the side of sample 7 (from Figure 12A Bottom view observed in the direction of arrow FD).

[0246] according to Figure 11C as well as Figure 12A , the incident surface 10i (10ia, 10ib, 10ic) of the light emitting element is shaped like a portion of an elliptical surface cut out in such a way that the normal of the surface is directed toward the observation point MP. As described in Example 1, in order to efficiently detect signal electrons, the incident surface 10i is preferably a spherical surface. However, since it is composed of a plurality of incident surfaces 10i, it is shaped close to an elliptical surface deviated from a spherical surface for reasons of manufacturing method, etc. In addition, the incident surface of this embodiment is not a complete elliptical surface. Figure 11C When viewed in a cross-sectional view, each incident surface becomes a plane (slant surface) with a different inclination.

[0247] For the reasons described in Example 1 for improving the detection efficiency of signal electrons, these incident surfaces are all tilted so that the incident angle θi is 30 degrees or less. Furthermore, when multiple light-emitting elements 10 are arranged in the direction of the light beam, gaps are created between the light-emitting elements in the direction of the light beam. Therefore, when observing each incident surface from the observation point MP, the light-emitting elements on the side closer to the sample 7 in each gap are concealed so that the gap is not visible from the observation point MP.

[0248] according to Figure 12B When the three light emitting elements 10 are observed from the bottom side, the extension line of the side surface of each light emitting element (at Figure 12BThe intersection of the two extended lines (dashed lines LD) is a point that is substantially equal in all three directions (a point on the central axis C). In other words, the central angle θc formed by the two extended lines (dashed lines LD) is the same in all light emitting elements (10a, 10b, 10c).

[0249] This is because, Figure 11B As shown in (a), a light-emitting element structure is used to seamlessly surround the central axis C using a detection element group 5g. A light-emitting element, which appears disc-shaped when viewed from above, is cut into π-shaped sections and processed. This arrangement arranges multiple light-emitting elements in the direction of electron beam irradiation. When the detection element group 5g is viewed from the sample side, the central angles θc of the multiple arranged light-emitting elements are equal. This achieves the following advantages: The light-emitting elements 10 can be densely arranged three-dimensionally around the central axis C, enabling the complete detection of signal electrons 102 emitted in various directions.

[0250] according to Figure 12B The three light guides 11a, 11b, and 11c have the same width WLGP (which may vary within a certain range of dimensional variation). This width WLGP is approximately the same as or smaller than the width WRS of the light receiving surface of the light receiving element. This is to improve the light utilization efficiency of the light guides.

[0251] If the light guide's emission surface 11o is larger than the light receiving surface 12i, light will be emitted to areas outside the light receiving surface, and most of this light will be lost (part of it will be scattered in the frame 12f of the light receiving element 12 and enter the detection surface 12d. See the structure for details). Figure 5 Therefore, by setting the width of the light emitting surface 11o of the light guide to be equal to or less than the width of the light receiving surface 12i, the effect of suppressing the loss is achieved.

[0252] If the width of the emission surface is wider than the width WSiPM of the light receiving element, the light from the emission surface 11o extending from the light receiving element will not reach the light receiving surface 12i and will be lost. Therefore, the width WLGP of the emission surface 11o is preferably equal to or less than the width WSiPM of the light receiving element (for example, less than 1.0 times, less than 1.1 times, less than 1.2 times, less than 1.3 times, less than 1.4 times, or less than 1.5 times).

[0253] Furthermore, to ensure uniform light distribution across the entire light-receiving surface, the emitting surface 11o is preferably the same size as the light-receiving surface 12i. Specifically, by making the widths of the emitting surface 11o and the light-receiving surface 12i equal (or different within a range of dimensional variation), both light utilization efficiency and uniform illumination are achieved. For example, if the width WRS of the light-receiving surface 12i is 3.0 mm, the width of the emitting surface 11o can be approximately 2.8 mm. This difference in width allows for uniformity within a range of dimensional variation.

[0254] In addition, if Figures 11A to 11C 、 Figure 12A 、 Figure 12B As shown, the structure of the light guide, where the width from the incident surface 11i to the exit surface 11o is kept constant rather than expanded, improves light utilization efficiency. As discussed in Example 4, in a light guide, if light narrows from an expanded state, it leaks and is lost. Therefore, if the light guide has an expanded shape, light leaks and is lost there. Therefore, in this embodiment, the widths of the incident surface, exit surface, and light-receiving surface of the light guide are approximately equal, achieving a balance between efficiency and uniform illumination.

[0255] Since the electron beam is absorbed tens of micrometers from the incident surface of the light emitting element, it is considered that the light is emitted almost entirely at the incident surface. In this case, the light emitted at the incident surface must propagate within the light emitting element and further through the light guide to reach the light receiving element.

[0256] like Figure 12B As shown, this structure has no portion where the width decreases from the incident surface 10i of the light emitting element to the light receiving element 12. That is, the width of the light emitting element increases from the incident surface 10ic toward the light guide incident surface 11ic, and the width of the light guide is constant.

[0257] As described above, when the cross-sectional area in the propagation direction becomes smaller, the light utilization efficiency decreases. Therefore, this structure of the optical system in which the width from the incident surface of the light-emitting element to the light-receiving surface of the light-receiving element does not decrease has the effect of suppressing the decrease in light utilization efficiency.

[0258] Furthermore, to shorten the distance between the three types of light guides 11 (the length of the optical path), the light-emitting elements 10 (light-emitting elements belonging to the same detection element group 5g) in the same azimuth direction are arranged so as to overlap in the direction of the light beam's illumination, and the light guides 11 connected to them are also arranged so as to overlap. That is, the multiple light guides 11 connected to the multiple light-emitting elements 10 have portions that overlap in the direction of the electron beam's illumination. This structure enables detection of signal electrons at each different polar angle in the same azimuth direction. In other words, in a given azimuth direction, information can be obtained about how many signal electrons were emitted at which polar angle. This structure achieves the effect of achieving polar angle discrimination in a given azimuth direction.

[0259] In particular, in the first direction, by arranging the light-emitting element, light guide, and light-receiving element in a straight line, the distance of the light guide 11 (the length of the optical path) in each of the three detection elements is shortened. Furthermore, in a configuration that achieves polar angle discrimination in the same azimuth direction, the distance of the light guide 11 is minimized by arranging the light-emitting element, light guide, and light-receiving element in a straight line. Shortening the distance of the light guide 11 (the length of the optical path) improves light utilization efficiency. This configuration achieves improved light utilization efficiency.

[0260] In addition, in the same detection element group 5g, the structure with the shortest distance between the light receiving surface 12ia of the light receiving element arranged most radially inward in the first direction and the incident surface 10ia of the corresponding light emitting element makes the overall optical system compact and improves light utilization efficiency.

[0261] like Figure 11B As shown in (a), a plurality of light receiving elements 12 are arranged in a row radially from the central axis C. Furthermore, the light emitting elements 10 and the light receiving elements 12 in the same azimuth direction are arranged in a row so that the shape of the light guide when viewed from above is straight and the distance between the incident surface 11i and the emitting surface 11o of the light guide is the shortest. As mentioned above, the light utilization efficiency is maximized when the light guide is straight. In addition, the shorter the distance, the less light loss, so the light utilization efficiency of this structure increases. Therefore, by arranging the light receiving elements 12 in a row and arranging the light guide 11 in a straight line when viewed from the sample side, the light utilization efficiency of the light guide is improved.

[0262] In addition, when polar angle discrimination is not performed in a certain azimuth direction, the light receiving elements 12 do not necessarily need to be arranged in a row. Figures 12C to 12E Modifications will be described. Figure 12C : is a bottom view of the detector 5 viewed from the sample side, Figure 12D It shows a top view from the side where the electron beam is irradiated. Figure 12E The three-dimensional structure of the detection element group 5g is shown. Figure 12D In the figure, the mounting substrate 13 is not shown. In order to avoid complication and facilitate observation, parts that cannot be seen are not described in any figure.

[0263] In this modified example, the detection element composed of the light emitting element 10b, the light guide 11b, and the light receiving element 12b rotates in the azimuth direction relative to the detection element composed of the light emitting element 10a, the light guide 11a, and the light receiving element 12a, and the detection element composed of the light emitting element 10c, the light guide 11c, and the light receiving element 12c. The rotation angle φh is the angle obtained by dividing 360 degrees by twice the number of divisions. Figures 12C to 12E In the example, it is 360 / (2×12)=15 degrees.

[0264] exist Figure 12D In the top view, the light receiving element 12a and the light receiving element 12c are arranged in a row in the radial direction, but the light receiving element 12b is located at a position rotated by an angle φh (15 degrees in the figure) in the azimuth direction relative to the light receiving element 12a. In addition, this structure can be said to be a structure in which the light receiving elements 12 are arranged in a staggered (sawtooth) shape along the first direction. The advantage of such a structure is that the light receiving elements can be arranged at a high density. Figures 12C to 12E In the structure of FIG, the distance between the light receiving element 12c farthest from the central axis C and the central axis C is the same as Figure 12A as well as Figure 12B In this way, the light receiving elements 12 can be shortened compared to the case where they are arranged in a row, thereby achieving an effect of further improving light utilization efficiency.

[0265] However, in order to perform polar angle discrimination in the same azimuth direction, the incident surfaces of the plurality of light emitting elements (three types, 10a, 10b, and 10c in this embodiment) performing polar angle discrimination need to be arranged within the same azimuth range in the spherical coordinate system.

[0266] That is, Figure 12A as well as Figure 12B The structure of the light emitting element shown in FIG. Figure 12B As described above, when observing the three types of light emitting elements 10 from the bottom side, it is necessary to use the extension line of the side surface of the incident surface in each light emitting element (at Figure 12B The light emitting elements are arranged so that the intersection of the three points (the dotted line LD in the figure) is approximately equal to each other (the point on the central axis C). In other words, when viewed from the bottom side, the incident surfaces 10i of the light emitting elements in the same azimuth direction need to be approximately included in the flash shape with the same central angle.

[0267] In the structure of the light emitting element that performs polar angle discrimination in the same azimuth direction, the light receiving element 12 is arranged in a row, that is, Figure 12B The structure shown is a structure that can make the distance of the light guide 11 (the length of the optical path) the shortest among the three types of detection elements.

[0268] Compare Figure 12A as well as Figure 12E It can be seen that in Figures 12C to 12E In the illustrated modification, the incident surface 10ib of the light emitting element is shifted in the azimuthal direction. Therefore, polar angle discrimination cannot be performed in the same azimuthal direction for the three light emitting elements.

[0269] Polar angle discrimination in the same azimuth direction has the following effect: by comparing the signals at each polar angle under the same azimuth, the information content of the three-dimensional structure is increased, thereby improving visual recognition. Therefore, when this effect is important, it is preferable to arrange the light receiving elements 12 in a row. However, when other effects such as light utilization efficiency and circuit area are prioritized, it is not necessary to arrange the light receiving elements 12 in a row. The arrangement of the light receiving elements 12 can also include a staggered arrangement, and various configurations can be adopted.

[0270] Next, the structural interference of the light guide at each vertex of the light emitting element 10 arranged in a regular polygonal shape will be described. Figure 12B The width WE of the emission surface 10o of the light emitting element is described in Figure 9C) is approximately equal to the width WLGP of the incident surface 11i of the light guide, but Figure 13A and 13B for detailed description.

[0271] Figure 13A FIG. 2 shows an example of the shape of the light emitting element 10 in Example 7. Figure 13B The shape of the light emitting element 10 in Example 7 is the same as that in Example 5 ( Figure 9C ) is an example of a shape after deformation. In addition, the interference of the light guide in the undivided regular polygonal light emitting element 10 is described in Example 5. The basic method of suppressing interference is the same.

[0272] exist Figure 13A as well as Figure 13B In the example, the light emitting element 10c and the light guide 11c adjacent to each other in the azimuth direction are described. Figure 13A At the vertex CP adjacent to the emission surface 10oc of the light emitting element, the light emitting element 10c is originally manufactured by dividing a disk, so there is no interference, but the light guide 11 connected thereto sometimes interferes due to size deviation. Therefore, Figure 13A This is an example in which the width WLGP of the incident surface 11i of the light guide is slightly smaller (for example, about 0.1-0.3 mm) than the width WE of the emission surface 10o of the light emitting element, thereby achieving the effect of suppressing interference.

[0273] Figure 13B This example illustrates the provision of a protruding portion 10g that radially outwardly protrudes from the emission surface 10o of the light-emitting element to guide light. In this case, since a gap is created between the emission surfaces 10oc of adjacent light-emitting elements, the width WLGP of the light guide's incident surface can be made larger than the width WE of the emission surface 10oc of the light-emitting element. This allows substantially all of the light emitted from the light-emitting element to enter the light guide 11c, thereby improving light utilization efficiency. Therefore, the provision of the protruding portion 10g suppresses interference with the light guide and improves light utilization efficiency.

[0274] For example, when the width of the light receiving surface is 3.0 mm, the width WLGP of the incident surface of the light guide can be set to 2.8 mm, and the width WE of the emission surface 10 oc of the light emitting element can be set to approximately 2.7 mm.

[0275] In addition, when the distance between the radial position of the starting point of the protruding portion 10g and the central axis C (the intersection when the side of the light-emitting element is extended) is set to LE, and the division in the azimuthal direction is set to the number Nazth, the approximate value of the width WE of the emission surface 10oc of the light-emitting element is roughly expressed by the relationship between the side and the side center distance of the polygon, and is given by the following formula 1.

[0276] WE=2·L E ·tan(π / Nazth ):Formula 1

[0277] As in Figure 12B As described in , if light utilization efficiency and uniform irradiation to the light receiving surface of the light receiving element are taken into consideration, the width W of the light receiving surface of the light receiving element is RS The width W of the light receiving surface is preferably the same as the width of the light guide's emission surface. RS The width W of the light emitting element's emission surface may be the same as the width of the incident surface of the light guide. E It is preferably less than or equal to the width of the incident surface of the light guide, or approximately the same (including slightly larger cases). Therefore, in general, the width W of the emission surface of the light emitting element is E Preferably less than or equal to the width W of the light receiving surface RS .

[0278] Taking this into account, the distance L E The following equation 2 is preferably satisfied based on equation 1. For example, when the width of the light-receiving surface is 3 mm and the light-emitting element is a 12-sided polygon, the distance L is preferably E Less than 5.6mm.

[0279] W RS / {2·tan(π / N azth )}≧L E : Formula 2

[0280] In addition, as in this example, when the light emitting element 10 is a regular polygon-based shape (a shape in which rectangles are connected to the outside of each side of the regular polygon) and the light receiving elements are arranged so as to surround the central axis C, the distance L between the central axis side surface of the innermost light receiving element 12a and the central axis C is SiPM (Refer to Figure 12B ) and the width W of the light receiving element SiPM The following formula 3 needs to be satisfied (assuming that the length of the light guide is the same in any detection element group and that there is no interference between the light receiving elements).

[0281] For example, when the width of the light receiving element is 3.4 mm and the shape is 12-sided, the distance L is preferably SiPM Greater than 6.3mm.

[0282] L SiPM ≧W SiPM / {2·tan(π / N azth )}:Formula 3

[0283] In addition, the structure satisfying Formula 3 is particularly preferred when the light receiving elements are arranged along the first direction. Figure 13B Formula 1 is derived from the structure of Figure 13AIn the structure of , by setting the distance LE as the distance between the radial position of the emission surface 10oc and the central axis C (the intersection when the side surface of the light emitting element is extended), similarly, formula 1 is established, and formulas 2 and 3 can also be applied to Figure 13A This embodiment is to suppress the interference of the structure. Figure 13A The structure is still Figure 13B The structures of are all set to satisfy the formula 2 and formula 3. In addition, with these distances L E and L SiPM The above-mentioned structure has the effect of suppressing interference, but the present invention is not limited to such a structure.

[0284] Furthermore, the structures described in Examples 1 to 6, such as the improvement of light utilization efficiency by the adhesive, can also be appropriately applied to Example 7, and the same effects can be obtained.

[0285] According to this embodiment, the effect of being able to distinguish polar angles is particularly significant in a thin structure. This point will be described below.

[0286] When the distance between the observation point MP and the light emitting element 10 is about 1 to 3 mm, the Figure 17 In the conventional structure described above, azimuthal angle discrimination can be achieved by arranging the light-receiving elements 12 so as to surround the central axis C. However, polar angle discrimination is difficult. This is because the majority of the signal electrons 102 (for example, those emitted within a polar angle range of 10 to 60 degrees) are concentrated and incident on the light-emitting element 10 closest to the inner side of the electron beam 101, making them undetectable. In particular, to separate and detect signal electrons emitted within a polar angle range of 10 to 50 degrees, a tiny light-emitting element entrance surface is required, making polar angle discrimination quite difficult.

[0287] In this embodiment, multiple light-emitting elements are arranged in the direction of the beam, and light-receiving elements are positioned farther from the electron beam than the light-emitting elements. The light emitted by each light-emitting element is then used by the light-receiving element to detect the signal. Furthermore, the light propagates in a first direction and then in a second direction. This divides the incident surface of the tiny light-emitting elements, enabling polar angle discrimination across a broad range of polar angles, including signal electrons emitted at smaller polar angles.

[0288] In other words, by concentrating the light-emitting elements at the center and positioning the light-receiving elements at a distance in the first direction, this structure can accommodate the entire optical system, from the light-emitting elements to the light-receiving elements, within the limited space between objective lens 4 and specimen 7. This achieves both reduced light loss due to the shortened optical path and polar angle discrimination due to the high-density segmentation at the center. This structure is particularly effective in achieving polar angle discrimination in locations where multiple signal electrons can be detected.

[0289] In addition, there are various methods for arranging the light beams of the light emitting elements in the irradiation direction. Figure 12A As shown, there is also an arrangement in which the incident surfaces of the light emitting elements are roughly arranged in a row along the irradiation direction of the light beam, such as Figures 12C to 12E As shown, there is also a case where the incident surfaces of the light emitting elements are arranged in a zigzag pattern along the irradiation direction of the light beam.

[0290] exist Figure 12A as well as Figure 12E In the embodiment, the difference in the arrangement of the light beams of the light emitting elements in the irradiation direction is caused by the difference in the arrangement of the light receiving elements in the first direction under the condition that the light guide is set as a straight line when viewed from above. In other words, the arrangement of the light beams of the light emitting elements in the irradiation direction is also affected by the shape of the light guide and the arrangement of the light receiving elements, and is therefore not limited to Figure 12A 、 Figure 12E Such an arrangement includes various arrangements such as one in which the number of divisions of the light emitting elements and the positional relationship are different depending on the position in the irradiation direction of the light beam.

[0291] If multiple light emitting elements are arranged in the irradiation direction of the light beam, the above-mentioned polar angle discrimination can be achieved, and signal saturation caused by an increase in the light beam amount can be suppressed. Therefore, multiple light emitting elements may be arranged in the irradiation direction of the light beam.

[0292] Furthermore, from the perspective of suppressing signal saturation caused by an increase in the amount of light beam, the arrangement of the light receiving elements 12 in the first direction does not necessarily need to be a straight line. For example, in order to suppress interference between the light receiving elements 12 in the bottom view, the light receiving elements 12 may be arranged in a meandering pattern (staggered or zigzag pattern) in the first direction. In such a case, for example, a light guide 11 that curves when viewed from above may be used.

[0293] Furthermore, when arranging the light-receiving elements 12 at a higher density, the number of light-receiving elements may be varied between the circumference close to the central axis C and the circumference farther away. In this case, the number of divisions in the azimuth direction may be different for each detection element included in the same detection element group 5g, or a light guide having a shape such as a light guide branching from one incident surface to multiple exit surfaces may be included.

[0294] Furthermore, various modifications can be made without departing from the concept of acquiring the signal electrons 102 at the minute incident surface 10i of the light emitting element near the central axis C and propagating and diffusing the light in the first direction.

[0295] [Example 8]

[0296] Figures 14A to 14D This is a diagram showing a structural example of the detector 5 of Example 8. Figure 14AIndicates a stereogram. Figure 14B (a) shows a bottom view. Figure 14B (b) indicates Figure 14B (a) Cross-sectional view along line AA. Figure 14C express Figure 14B (b) A partial enlarged view. Figure 14D It is a perspective view of the detection element group 5g.

[0297] This example is an example in which the structure of Example 7 is modified, and description of the same structure as Example 7 is omitted. The difference from Example 7 is that planar elements are used as the light emitting elements 10 (10a, 10b, 10c).

[0298] Crystalline light-emitting elements can be processed into various shapes, but there are also planar light-emitting elements such as thin plates or films, and it is preferable to use these light-emitting elements as appropriate. For example, a thin film formed from a powdered phosphor has the characteristic of high light extraction efficiency from the powder, and there are materials with high luminous intensity.

[0299] Examples of such materials include YSO (Y2SiO5:Ce). However, as a crystalline light-emitting element material, materials such as YAP, YAG, GGAG, and GOS described in Example 1 can also be used in the form of powders. Furthermore, even the crystalline light-emitting elements described in Example 1 can be easily processed and thus used as planar elements. In such cases, the configuration of this example can be applied.

[0300] In addition, as materials with a fast response speed from light emission to extinction, semiconductor materials such as ZnO and GaN can be cited. These materials are often used as planar thin plates. In particular, in the case of light-emitting elements with an internal quantum well structure, the quantum well structure is formed on a flat substrate and is therefore usually used as a thin plate. A representative example of a light-emitting element with a quantum well structure is a GaN scintillator, which uses a quantum well structure composed of stacked InGaN and GaN as the light-emitting portion. Of course, the present invention does not limit the materials of the light-emitting element.

[0301] In this embodiment, a structure suitable for a planar element is provided. Figures 14A to 14D 1 shows a case where a GaN scintillator plate is used as the light emitting element 10. Figure 14B (b) Figure 14C as well as Figure 14D As shown, compared with Example 7, the light guide 11 is extended to the vicinity of the center, and the emission surface 10 o of the light emitting element is bonded to the incident surface 11 i of the light guide 11 .

[0302] Furthermore, the light guide incident surface 11i is tilted relative to the irradiation direction of the electron beam 101 so that the normal of the incident surface 10i of the light emitting element faces the observation point MP. The light guide incident surface 11i is tilted so that the incident angle θi of the signal electrons 102 on the incident surface 10i of the light emitting element is 30 degrees or less.

[0303] In addition, the inclined incident surface 11i also has the effect of reflecting light in the first direction (arrow D1). This effect is described below. Figure 14C As shown in the ray Ray11, some light entering light guide 11b re-enters light-emitting element 10b, is reflected by incident surface 10ib of the light-emitting element, re-enters light guide 11b, and propagates toward light-receiving element 12. While the example of light re-entering light-emitting element 10b and reflecting off incident surface 10ib has been described, there are also cases where light does not re-enter light-emitting element 10b but instead undergoes Fresnel reflection at the interface between light guide 11b and light-emitting element 10b and follows the same path. Because of this path, the inclined incident surface 11i also serves to reflect light in the first direction (arrow D1).

[0304] In the case of a planar light emitting element, the amount of light emitted in the normal direction of the plane increases, and therefore a path like the light ray Ray11 is easily generated, and the effect of the inclined incident surface 11i is greater.

[0305] like Figure 14A as well as Figure 14D As shown, the incident surface 10i of the light-emitting element is arranged to three-dimensionally cover the observation point MP, that is, to have a range not only in the radial direction of the electron beam 101 but also in the irradiation direction. To achieve three-dimensional coverage by combining the two planes, the planar shape of the incident surface 10i of the light-emitting element is a trapezoid with the side longer on the sample 7 side. Other shapes such as a hexagon are also possible, but the trapezoidal shape is preferred to seamlessly surround the observation point MP, and is also simple to process and practical.

[0306] Figure 14E as well as Figure 14F An example of a structure when a light-emitting element using powder is shown. Figure 14E As shown in FIG. 1 , a powder film 10p may be formed on a substrate 10s such as glass, and the substrate 10s on which the powder film 10p is formed may be used as the light emitting element 10. Figure 14F As shown, the powder film 10 p may be directly formed on the incident surface 11 i of the light guide 11 to form the light emitting element 10 .

[0307] In either case, the incident surface 10i of the light emitting element is the vacuum side surface of the powder film (the air side surface, the surface not in contact with the substrate or the light guide). Figure 14E), the emission surface 10o is the surface of the substrate 10s that is opposite to the incident surface 11i of the light guide (the surface mounted on the light guide 11), and when a film is formed on the light guide 11 ( Figure 14F ), the emission surface 10o is the surface of the powder film opposite to the incident surface 11i of the light guide.

[0308] The incident surface 10i preferably does not expose the powder and is covered with a protective film or an aluminum film to prevent static electricity (not shown). The powder film is formed by the adhesion of powdered phosphor 10ph. Therefore, there is some variation in thickness. The average thickness is about several μm to several tens of μm.

[0309] In this embodiment, the incident surface 10i of the light-emitting element is tilted relative to the irradiation direction of the electron beam 101, that is, tilted relative to the first direction (arrow D1). However, if only the effect of light reflection in the first direction is considered, as described in the first embodiment, as a modified example, even if the incident surface 10i is parallel to the first direction, the same effect can be achieved by tilting the surface opposite to the incident surface 10i in the direction of light beam irradiation relative to the first direction.

[0310] Figure 14G A cross-sectional view near the incident surface 10i in this modified example is shown. Incident surface 10i is parallel to the first direction (arrow D1), but in the light guide 11, a surface 11ir opposite to incident surface 10i in the direction of light beam illumination is tilted relative to the first direction. In this case, light is reflected from surface 11ir and propagates in the first direction. Alternatively, both incident surface 10i and the opposite surface 11ir may be tilted relative to the first direction.

[0311] like Figure 14C As shown, light emitted by light-emitting element 10 enters light guide 11 and propagates in a first direction (the direction of arrow D1). In the optical system composed of the light-emitting element and light guide, the region of light propagating in the first direction forms a first optical path. The optical path that guides light from the first optical path toward the light-receiving surface (the direction of arrow D2) forms a second optical path.

[0312] In the structures described in Example 1 and Examples 3 to 7, by adopting the structure exemplified in this embodiment near the light-emitting element 10 and the incident surface 11i of the light guide, the various effects described in Example 1 and Examples 3 to 7 can be achieved even when the light-emitting element is planar. In other words, the structure in which a planar light-emitting element is provided at the tip of the light guide can be appropriately applied to the structures described in Example 1 and Examples 3 to 7, regardless of the method of dividing the light guide, etc., and the same effects can be achieved.

[0313] [Example 9]

[0314] The various features described in Examples 1 to 8 can be used in combination as appropriate. Figures 15A to 15C , and descriptions are given of combination examples and component modifications.

[0315] Figure 15A This diagram shows a detection element group 5g that includes a detection element having a light guide 11 (composed of a light-emitting element 10b, a light guide 11b, and a light-receiving element 12b), other detection elements (composed of a light-emitting element 10c, a light guide 11c, and a light-receiving element 12c), and another detection element that does not have a light guide 11 (composed of a light-emitting element 10a and a light-receiving element 12a).

[0316] A detection element without light guide 11 has the shortest optical path, and the area where light propagates is a flat surface that can be manufactured from a flat plate or disk. Because the plate material of light-emitting element 10 can be cut at an angle, this embodiment utilizes a flat plate or disk-shaped light-emitting element to provide a light guide function.

[0317] The light emitting element 10a forms an optical path for guiding light in a first direction (the direction of arrow D1) and an optical path for guiding light in a second direction (the direction of arrow D2). Figure 6B The light emitting element 10 shown in (b) has the same functions as those described in the second embodiment.

[0318] The two detection elements with light guide 11 have a three-dimensional shape due to the bending of the second optical path. This makes it difficult to machine the light-emitting element into this shape, or the processing time is long, making it impractical. Therefore, in cases where the shape cannot be easily machined from a sheet material, the use of a light guide is preferred. This structure is an example of a combination of a structure using a light guide and a structure not using a light guide, depending on the light propagation path.

[0319] Figure 15B This is an example of a configuration for producing a first image using one of the detection elements, where the primary signal source is X-rays, and a second image using another detection element, where the primary signal source is electrons. Specifically, the light-emitting element of one detection element (e.g., light-emitting element 10a) is made of a material for highly transmissive radiation such as X-rays, while the light-emitting elements of the other detection elements (e.g., light-emitting elements 10b and 10c) are made of a material for electrons.

[0320] If the electron beam 101 is irradiated on the sample 7, X-rays are generated along with the signal electrons 102. This structure is used to detect the signal electrons 102 and the X-rays as signals. In order to efficiently detect X-rays, it is preferable to use a light-emitting element that emits light efficiently by X-rays. That is, in order to distinguish and detect X-rays and signal electrons separately, light-emitting elements of different materials can be used for X-rays and electron beams. As the material of the light-emitting element for X-rays, if GGAG (Gd3(AlGa)5O 12 )、YAG(Y3Al5O 12 )、LuAG(Lu3Al5O 12 ), GOS(Gd2O2S), YOS(Y2O2S), GSO(Gd2SiO5), LSO(Lu2SiO5), YSO(Y2SiO5), CWO(CdWO4), BGO(Bi4Ge3O 12 ), CsI, NaI, YAP, etc., can obtain good properties. In addition, some materials can be used with both X-rays and electrons. In addition, materials other than those listed here can also be used.

[0321] Because electron beams have lower penetration than X-rays, they are preferably detected by two light-emitting elements 10b and 10c located close to sample 7. Highly transmissive radiation, such as X-rays, is barely absorbed by light-emitting elements 10b and 10c or light guides 11b and 11c, but instead passes through and reaches light-emitting element 10a, the X-ray detector, enabling detection. By using different light-emitting materials on the side closer to the sample and farther from the sample, and placing the X-ray detecting light-emitting element on the side farther from the sample, the X-ray detector can efficiently detect only X-rays, rather than electrons.

[0322] This structure allows for the detection of X-rays and electron beams, i.e., it is possible to construct an SEM image of X-rays alone using a certain detection element and an SEM image of electron beams mainly using another detection element.

[0323] Furthermore, although the materials of the light emitting elements are different for X-rays and electron beams, the present invention is not limited thereto. YAP, YAG, etc. can be used for both electron beams and X-rays, so the same material may be used.

[0324] Furthermore, the X-ray detection element is constructed without a light guide. This is because radiation passes through various objects, including the sample 7, and is emitted over a wide area. Therefore, extending the light-emitting element 10a increases the area of ​​the incident surface and thus increases the signal intensity. This light-emitting element 10a has an optical path that transmits light to a light-receiving element 12a (in the direction of arrow D1) located at a distance in the first direction, then propagates through a reflective surface 10ra to a light-receiving surface 12ia (in the direction of arrow D2). Alternatively, the X-ray detection element may include a light guide.

[0325] Furthermore, the light-emitting element that efficiently detects X-rays is positioned farthest from the sample. However, since signal electrons 102 are detected at the incident surface 10i at the tip of the light-emitting element, other arrangements are possible. For example, the lengths can be varied radially, with the light-emitting element 10b positioned in the middle designated for X-rays and the light-emitting element 10c closest to the sample designated for X-rays. The optimal position for X-rays can be determined based on considerations including the shape of the incident surface.

[0326] This structure for simultaneous detection of X-rays and electron beams is achieved by having an optical system that arranges multiple light-emitting elements in the direction of light beam illumination, separates the light-emitting elements for detecting X-rays from those for detecting electron beams, and arranges light-receiving elements in a first direction, allowing light from each light-emitting element to propagate independently to the light-receiving element. Specifically, the structure of the detector element group described in Example 9 enables simultaneous detection of different quanta (in this case, X-rays and electron beams). Using only the X-ray detection elements as in Example 2 provides a more preferred structure.

[0327] Furthermore, it is preferable to use multiple light-emitting elements, using either X-ray or electron beam light-emitting elements, to improve detection efficiency. Furthermore, it is preferable to use the detection element farthest from the sample for X-rays. This reduces the probability of electron beams entering the X-ray light-emitting element, allowing the creation of X-ray-only images.

[0328] Figure 15C This shows an example of a structure in which the cross-sectional shape of the light guide 11 is curved. In this case, the cross-sectional shapes of the light-emitting element 10 and the light guide 11 may not have a surface completely parallel to the first direction (arrow D1). However, the light-receiving surface 12i of the light-receiving element is located at a position separated from the incident surface 10i of the light-emitting element in the first direction. The light-receiving surface 12i is located on the side of the light-emitting element 10 from which the electron beam 101 arrives. Therefore, the optical path connecting the incident surface 10i and the light-receiving surface 12i includes an optical path that generally extends in the first direction and an optical path that generally extends in the second direction.

[0329] When the cross-sectional shape is curved, it is difficult to strictly define the first and second optical paths. However, for example, the following definitions are possible. In the light guide 11, the area near the radially inner end of the electron beam 101 forms a first optical path that guides light in a first direction. On the other hand, in the light guide 11, the area near the radially outer end of the electron beam 101 forms a second optical path that guides light in a second direction. The portion other than these (the portion between the first and second optical paths) can be referred to as an optical path connecting the first and second optical paths.

[0330] In this way, the light guide 11 can form at least a part of the second light path. Figure 15C In the example, the light guide 11 also forms the first light path, but the first light path can also be formed by a light-emitting element. Furthermore, a portion of the second light path (particularly the area on the side of the first light path) can also be formed by a light-emitting element, and the entire light path including the first and second light paths can also be formed by a light-emitting element (i.e., without using a light guide).

[0331] In addition, other definitions are possible. Figure 15C As shown, the first optical path may be defined as the path extending from the incident surface 10i in the first direction (arrow D1) to the intersection with the light emitting element 10 or the light guide 11, and the path from the intersection to the light receiving surface 12i as the second optical path. This definition also applies when the cross-sectional shape is a straight line.

[0332] In addition, Figure 15C In the figure, the second direction is represented by a straight line (arrow D2). However, when the cross-sectional shape is a more complex curve, the second direction sometimes intersects with the cross-sectional shape and cannot be clearly defined. However, in this case as well, the light path from the above-mentioned intersection to the light receiving surface 12i can be set as the second light path.

[0333] Alternatively, the definition can be based on the methods described in Example 1 and other examples, or on the characteristics of the optical path. If the concepts and characteristics are the same, the appropriate definition method can be used depending on the shape. For example, the second optical path can be defined as the point where the amount of light propagating in a direction different from the first direction begins to increase.

[0334] Furthermore, particularly when the detector thickness is approximately the same as or slightly greater than the size of the light-receiving element 12 (in this embodiment, the light-receiving element is 3.4 mm in size and the detector thickness is 3 to 7 mm), the light propagation distance in the first direction is longer than the propagation distance in a direction perpendicular to the first direction. This is because the detector is thin and cannot diffuse light in the thickness direction, so the light propagates in the first direction, thereby diffusing the light.

[0335] Figure 15CEach light guide (11a, 11b, 11c) has an optical path for propagating light in a first direction (arrow D1) and an optical path for propagating light in a second direction (arrow D2). The cross-sectional shape can be appropriately selected to be a curved surface or a straight line, depending on the positional relationship between the incident surface 10i of the light-emitting element and the light-receiving surface 12i of the light-receiving element. In either case, the optical system composed of the light guide and the light-emitting element has a first optical path and a second optical path, with the light-receiving element arranged and positioned away from the light-emitting element in the first direction.

[0336] In addition, all light guide shapes have a reflective surface 11r, opposite the light-receiving surface 12i, which reflects a portion of light traveling in the first direction in the second direction. The normal to the reflective surface 11r will be described. The reflective surface 11r is a surface whose normal is not perpendicular to the first direction. If the normal vector of the reflective surface, which points outward from the light guide, is defined as the normal Nr, the normal Nr is inclined radially outward.

[0337] [Variation of Example 1]

[0338] Figure 15D A modification of Example 1 is shown. Figure 2A as well as Figure 2B In the embodiment, the light receiving surface 12i is approximately parallel to the first direction (arrow D1), but can also be tilted. As an example of tilting to the extreme, it is also considered to configure the light receiving element longitudinally so that the first direction (arrow D1) is approximately perpendicular to the light receiving surface 12i. When the first direction is approximately perpendicular to the light receiving surface 12i, the concept of detecting the light with the signal electron 102 as the center and causing the light to propagate and diffuse along the first direction is the same, showing the same effect as described in Example 1. However, since the second direction is consistent with the first direction, the structure is different from that of Example 1.

[0339] exist Figure 15D The structure and Figure 2A The major difference between the structures of FIG2B and FIG2B is that the light receiving surface 12i of the light receiving element 12 is oriented toward the center, and light propagates in the first direction to reach the light receiving surface 12i. In other words, the normal to the light receiving surface 12i can be said to be approximately parallel to the first direction, or to be oriented in the direction of the electron beam 101 (radially inward).

[0340] In this variation, as in the above embodiments, the detector 5 has a transparent area (an area formed by the light emitting element 10 and the light guide 11) that propagates light from the incident surface 10i where the signal electron 102 in the light emitting element 10 is incident to the light receiving surface 12i of the light receiving element 12.

[0341] exist Figure 15DIn the embodiment, the light receiving element 12 has an electrode on the side and is mounted on the mounting substrate 13 by welding or the like. As another mounting method, in order to stand vertically relative to the mounting substrate 13, it is mounted on the mounting substrate 13 via an L-shaped metal fitting or the like. When using accessories such as L-shaped fittings, electrical connection can be performed using leads. In this structure, light propagating in the first direction reaches the light receiving surface 12i without changing direction, so the light utilization efficiency becomes higher. In addition, since there is no light receiving element between the mounting substrate 13 and the first optical path, the detector can be made thinner (the axial dimension can be reduced) accordingly.

[0342] exist Figure 15D In the example, the normal to the light-receiving surface 12i is parallel to the first direction, but this does not necessarily have to be strictly parallel. For example, the normal to the light-receiving surface 12i can be configured to form an angle of less than 10 degrees, less than 20 degrees, less than 30 degrees, or less than 45 degrees with the first direction. Light utilization efficiency can be improved by adjusting this angle. Furthermore, while this depends on the shape of the incident surface 10i, in most cases, light utilization efficiency is highest when the normal to the light-receiving surface 12i is parallel to the first direction.

[0343] [Variation of Example 2]

[0344] Figure 15E This represents a modified example of Example 2. This structure can also be considered as Figure 15D The modification shown is a further modification example. In Example 2 ( Figure 6A as well as Figure 6B ), the light receiving surface 12i is substantially parallel to the first direction (arrow D1), but there are also cases where it is tilted. As an example of tilting to the extreme, it is also considered to configure the light receiving element to be longitudinal in a manner that the first direction is substantially orthogonal to the light receiving surface 12i.

[0345] exist Figure 15D The example without light guide in the structure described in Figure 15E The advantages of making the light receiving surface 12i perpendicular to the first direction are as follows: Figure 15D The effect of canceling the light guide 11 is as described in Example 2 ( Figure 6A as well as Figure 6B ), since there is no light guide 11, there is no bonding process between the light guide and the light emitting element, and the light guide and the light receiving element, so assembly is easy; since one interface is reduced, the reduction in light utilization efficiency caused by interface reflection can be suppressed.

[0346] exist Figure 15EIn the example, the normal to the light-receiving surface 12i is parallel to the first direction, but this does not necessarily have to be strictly parallel. For example, the normal to the light-receiving surface 12i can be configured to form an angle of less than 10 degrees, less than 20 degrees, less than 30 degrees, or less than 45 degrees with the first direction. Light utilization efficiency can be improved by adjusting this angle. Furthermore, while this depends on the shape of the incident surface 10i, in most cases, light utilization efficiency is highest when the normal to the light-receiving surface 12i is parallel to the first direction.

[0347] [Example 10]

[0348] In Examples 1 to 9, we described detectors that can efficiently detect signal electrons, radiation, and other quanta emitted from an observation point, and that can output electrical signals without saturation even when the amount of signal electrons, radiation, and other quanta incident on the detector increases. The use of these detectors enables further functions, and these functions will be described in Example 10.

[0349] Example 10 is a measuring device equipped with the detector of Example 7. Example 6 provides a detection element 5e for each azimuth angle, enabling azimuth angle discrimination. Furthermore, Example 7 arranges multiple light-emitting elements 10 in the direction of the light beam's illumination, providing a detection element for each polar angle. This enables not only azimuth angle discrimination but also polar angle discrimination. Specifically, in Example 10, multiple light-emitting elements 10 are arranged in the direction of the light beam's illumination, and when the azimuth angle is defined with the light beam's illumination direction as the central axis, multiple light-emitting elements 10 are also arranged in the azimuth angle direction.

[0350] In Example 6, 12 detection elements are used, and in Examples 7 and 8, 36 detection elements are used, enabling each to output a signal from the signal electrons 102. In this case, the number of signal electrons 102 incident on each detection element is 1 / 12 and 1 / 36, respectively, of the total number of signal electrons 102 incident on the detector. For example, if the number of signal electrons is 1 / 36, and the electron beam 101 is used at approximately 1 nA or less without increasing its intensity, the interval between signal electrons 102 incident on each detection element will be approximately tens to hundreds of nanoseconds.

[0351] On the other hand, the response time from the start of the light-emitting element 10 to the end of the light-emitting element 10 is about tens to hundreds of nanoseconds. This response time becomes the response time of the detector required to detect one signal electron 102. By using elements that can be detected individually as in Examples 6 to 8, the incidence interval of the signal electron 102 on each detection element can be extended to more than the response time, and the signal electron 102 can be detected as a discrete pulse signal. That is, the number of signal electrons 102 can be counted as the number of pulse signals according to the irradiation position of the electron beam 101, and an SEM image can be generated based on the pulse count (number of signal electrons), thereby achieving improved visibility based on the new observation image.

[0352] Furthermore, in detectors that utilize significantly improved light utilization efficiency, such as those described in this specification, the pulse wave height and the energy of the signal electron 102 are roughly proportional. Therefore, the energy of the signal electron 102 can be measured based on the pulse wave height, allowing the signal to be identified based on the energy of the signal electron 102. Distinguishing a signal based on energy is called energy discrimination. Alternatively, distinguishing a signal based on the pulse signal's wave height can also be called wave height discrimination.

[0353] By using the detectors described in Examples 6 to 8, which are capable of individual detection and high light utilization efficiency, it is possible not only to count pulses but also to perform energy discrimination. Energy discrimination can improve image contrast or obtain depth information about the object being observed, further enhancing visual recognition.

[0354] Furthermore, if light utilization efficiency is low, the probability of emitted photons reaching light-receiving element 12 is low, resulting in greater variation in the number of photons reaching light-receiving element 12. Since the number of photons emitted by signal electrons with similar energies remains largely constant, low light utilization efficiency makes it impossible to discern these differences in photon number. In other words, low light utilization efficiency reduces energy resolution, making energy discrimination impossible.

[0355] use Figures 16A to 16C , describing an example of the structure of the measuring device of Example 10. Figure 16A Figure 1 shows a portion of the detector. Each light-receiving element 12 is wired to transmit an individual electrical signal to the detection circuit 15. Generally, the output from the light-receiving element 12 is a current signal. The detection circuit 15 converts this current signal into a readily processable voltage signal and amplifies it. Furthermore, the detection circuit 15 of this embodiment converts the resulting voltage signal into a digital form through analog-to-digital conversion and stores it in a storage device (not shown) within the system control unit 8 or the like.

[0356] Figure 16B 1 is a graph showing the voltage signal Sv generated by the detection circuit 15. The vertical axis represents voltage, and the horizontal axis represents time. This graph shows an example of a case where the amount of electron beam 101 is sufficiently low, and shows five pulse signals corresponding to five signal electrons 102.

[0357] Pulse width PW roughly represents the response time of the detection element, and pulse height pH represents a quantity proportional to the energy of the signal electron 102. Therefore, by measuring the pulse height pH, the energy of the signal electron 102 can be measured. However, strictly speaking, the average of the pulse height values ​​obtained by creating a histogram of the pulse height pH, removing noise on the low pulse side, and fitting a Gaussian distribution around the peak of the histogram is proportional to the energy of the signal electron.

[0358] like Figure 16BAs shown, when the pulse interval PI is longer than the detection element's response time, or pulse width PW, the pulse wave height PH can be accurately measured. When multiple signal electrons 102 enter the detection element within its response time, multiple pulse signals overlap. When the number of signal electrons entering within the response time becomes sufficiently large, the voltage signal Sv becomes a continuous curve, making the individual pulses indistinguishable.

[0359] As described in Examples 6 to 8, by employing a configuration in which multiple detection elements are arranged and the electrical signals from these detection elements are independently output, the number of signal electrons incident on each detection element can be reduced, and the pulse interval PI in each detection element can be lengthened. This reduces pulse overlap, allowing the pulse height PH to be measured, and the energy of the signal electrons 102 to be measured. Specifically, the configurations described in Examples 6 to 8 not only suppress signal saturation in the light-emitting element 10 but also enable energy discrimination of the signal electrons 102.

[0360] In an electron microscope, signal electrons scattered at a deeper position of the sample 7 lose more energy than before entering the sample 7. Therefore, the energy of the signal electrons includes information related to the structure of the sample 7 in the depth direction. As mentioned above, in the case of semiconductor inspection devices in particular, since the semiconductor structure in recent years is three-dimensional, the observation of the three-dimensional structure has become important. Therefore, in order to obtain information in the depth direction, it is important to effectively utilize the energy information of the signal electrons 102. In addition, the energy spectrum of the signal electrons 102 varies depending on the component distribution of the sample, so the energy of the signal electrons also includes information related to the composition of the sample 7, and the component distribution can also be observed.

[0361] By using the wave height discrimination of this detector, which has multiple detection elements capable of individually detecting the aforementioned signals, energy information of the signal electrons is extracted, thereby improving visibility when observing the structure and component distribution in the depth direction of sample 7. For example, when a measurement device such as an SEM has multiple detection elements composed of at least light-emitting elements and light-receiving elements and capable of individually detecting signals, by generating an image based on information related to the energy or quantity of the signal electrons, the user can better visually recognize the structure in the depth direction in the image.

[0362] Furthermore, in Examples 1 to 8, the incident surface 10i of the light-emitting element is configured as a spherical surface, thereby reducing the incident angle θi and fully absorbing the energy of the signal electrons. However, these structures are preferred for energy discrimination. This is because energy discrimination involves absorbing as much energy as possible from the signal electrons and measuring the energy based on the amount of luminescence generated by this energy. However, if the luminescence amount also varies with the incident angle, it becomes unclear whether the discrimination is based on energy or angle. Therefore, for energy discrimination, it is desirable to reduce the incident angle θi, and a configuration with an incident angle θi of less than 30 degrees is particularly preferred.

[0363] Figure 16C An example of a graphical user interface 16 (GUI) for improving visibility based on energy discrimination (wave height discrimination) is shown in the figure. This GUI is for energy discrimination using the detector described in Example 7. The azimuth direction is separated into 12 directions, and the polar direction is separated into 3 directions. The top section of the GUI displays a filtered image 16a generated by energy discrimination and an image 16b using all signals. Based on these images, the visibility of the filtered image can be improved, as described below.

[0364] This example is a display example in which the sample 7 is irradiated with a 50 keV electron beam 101 . The maximum energy of the signal electrons 102 is the same as the energy of the electron beam 101 , 50 keV.

[0365] The three graphs in the middle section of the GUI represent the energy spectra of the detection elements, representing spectrum 16c, spectrum 16d, and spectrum 16e, respectively. In this example, spectrum 16c is a spectrum obtained by averaging the spectra detected by the radially inner detection element in 12 azimuth directions. Similarly, spectra 16d and 16e are spectra corresponding to signal electrons detected by the detection element in the radial middle position and the detection element in the radially outer position. That is, spectrum 16c is the spectrum of signal electrons 102 detected flying in the direction of a small polar angle, and 16d and 16e are the spectra of signal electrons detected flying in the direction of a middle polar angle and a direction of a large polar angle, respectively. By displaying the spectrum for each polar angle, it is easy to perform energy discrimination and polar angle discrimination at the same time. In addition, the chart in the middle section can also be generated for each light-receiving element. Furthermore, numerical values ​​can also be output as spectral data to a file, etc.

[0366] In the three graphs in the middle section of the GUI, the horizontal axis represents energy, and the vertical axis represents the frequency of detected signal electrons corresponding to each energy level. The horizontal axis also takes into account energy-related quantities such as peak value. The solid and dashed lines in each graph represent the energy spectrum at the locations indicated by circles and triangles in the filtered image. In this example, the sample materials at the locations indicated by circles and triangles are different.

[0367] Using this energy spectrum, an energy band is selected for generating a filtered image. The energy band used for image generation is the interval between the dotted line 16j and the dashed line 16k. In this example, since the frequency of circles (solid line) is greater than the frequency of triangles (dotted line) in all energy bands in spectra 16c and 16d, signals of all energy bands are obtained to increase contrast. In spectrum 16e, the dotted line 16j representing the lower limit is set to an energy greater than the intersection of the frequency of circles and the frequency of triangles, so that the frequency of circles only becomes an area greater than the frequency of triangles. The dashed line 16k representing the upper limit is set to a value slightly smaller than the maximum value of energy, except for areas with small frequency differences.

[0368] Of course, the method for selecting the energy band for image generation is not limited to this, and various algorithms exist. These algorithms can be installed as programs in the charged particle beam apparatus 1, or they can be subsequently executed by loading a program (including scripts, macros, etc.) that describes the algorithms. The charged particle beam apparatus 1 can include a processor, and by executing the program on the processor, the charged particle beam apparatus 1 can implement the functions of each embodiment.

[0369] Use checkbox 16f to select the data to be displayed in filtered image 16a. The "S," "M," and "H" boxes marked in checkbox 16f represent the data sets corresponding to spectra 16c, 16d, and 16e, respectively. If "H" is selected, filtered image 16a is generated using the electrical signals of signal electrons 102 belonging to the energy band enclosed by dashed line 16j and dashed line 16k in spectrum 16e. If all checkboxes 16f are selected, image 16a is generated using the electrical signals of signal electrons 102 belonging to the energy band enclosed by dashed line 16j and dashed line 16k in all spectra 16c, 16d, and 16e.

[0370] In the pull-down menu 16g, select the data processing in the azimuthal direction in the generation of spectra 16c, 16d and 16e. Figure 16C In the example, the "average" method is selected, which averages the spectrum in 12 azimuth directions. Alternatively, only a portion of the detection elements (e.g., Figure 11B Spectra of the detection elements in detection element groups 5g6 to 5g8 can be averaged, or spectra of only the detection elements belonging to detection element group 5g1 can be specified. In this way, various processing operations can be performed using pull-down menu 16g, allowing for appropriate settings to improve image visibility. Furthermore, the contents of pull-down menu 16g can be appropriately set by those skilled in the art.

[0371] Text boxes 16h and 16i respectively represent the minimum and maximum values ​​of the energy band when generating filtered image 16a, that is, the values ​​of dotted line 16j and single-dot chain line 16k in spectra 16c, 16d, and 16e. If a numerical value is input into these text boxes, the charged particle beam device 1 can also set the input value to the minimum and maximum values ​​of the energy band to represent it. Alternatively, when the user moves dotted line 16j and single-dot chain line 16k on the GUI, the charged particle beam device 1 can also set the moved values ​​to the minimum and maximum values ​​of the energy band and display them in the text boxes.

[0372] Using this GUI to generate a highly visible filtered image 16a is very convenient. Due to the good field of view, it is easy to create an image with good visibility. In this example, the difference in signal intensity (frequency difference) between the circle and triangle positions, i.e., the increase in contrast, is used as an indicator of good visibility. However, this is not limiting, and visibility can also be appropriately determined based on factors such as the SNR (Signal-to-Noise Ratio) and the CNR (Contrast-to-Noise Ratio).

[0373] In addition, although many tasks of the GUI are performed manually, they can be appropriately automated. When automated, various optimization methods such as Bayesian optimization, AI (Artificial Intelligence), etc. can also be used.

[0374] As in Examples 6 to 8, in a measuring device having a detector capable of individually detecting pulses, by using a GUI that displays quantities related to energy such as energy spectrum or wave height and matters related to the control of such quantities, and displays quantities related to the orientation and position of the detector and matters related to the control of such quantities, it is possible to easily perform energy (wave height) discrimination and improve visibility brought about by angular discrimination such as polar angle, thereby constructing an optimal image.

[0375] Of course, if the algorithm is created in advance, a GUI that automatically generates filtered images without displaying a control GUI (checkboxes, text boxes, pull-down menus, etc.) can also be provided. However, when creating the algorithm or making fine adjustments to visual recognition, it is convenient to have such a control GUI, or a function to output spectral data for each polar angle, or a function to read in the program.

[0376] The GUI described in this embodiment is an example, and various other forms can be adopted. For example, a GUI dedicated to polar angle discrimination or a GUI dedicated to energy discrimination may be used.

[0377] In each embodiment of this specification, an electron microscope using an electron beam, particularly a scanning electron microscope, is described as an example of a charged particle beam device. However, as described at the beginning of Embodiment 1, the present invention is not limited thereto.

[0378] The quantum beam irradiated to the sample is not limited to an electron beam, and may be a particle beam such as ions, or a beam such as X-rays or gamma rays.

[0379] In addition, if the detector is a compact detector placed near the observation point, a better effect is achieved, but the present invention is not limited to this.

[0380] The observation point is not limited to the beam irradiation position of the sample; the collision point of two beams can also be considered. Furthermore, this technology is effective even for detectors placed far from the observation point, detectors located in narrow areas, and detectors where the shape of the light-emitting element's emitting surface differs from the shape of the light-receiving element's light-receiving surface, thus enabling a wide range of applications.

[0381] Furthermore, the present invention is not limited to the above-described embodiments and includes various variations. For example, the above-described embodiments are examples described in detail to facilitate understanding of the present invention and are not necessarily limited to having all the described structures. Furthermore, a portion of the structure of one embodiment can be replaced with a portion of the structure of another embodiment, and a portion of the structure of another embodiment can be added to the structure of one embodiment. Furthermore, with respect to a portion of the structure of each embodiment, other structures can be added, deleted, or substituted.

[0382] Explanation of symbols

[0383] 1: Charged particle beam device (measurement device)

[0384] 2: Electron source

[0385] 3: Scanning deflector

[0386] 4: Objective lens

[0387] 5: Detector

[0388] 6: Sample conveyor

[0389] 7: Sample

[0390] 8: System Control Department

[0391] 9: Monitor

[0392] 10: Light-emitting element

[0393] 11: Light guide

[0394] 12: Light receiving element

[0395] 13: Install the baseboard

[0396] 14: Opening

[0397] 15: Detection circuit

[0398] 16: Graphical User Interface

[0399] 101: Electron Beam

[0400] 102: Signal Electronics

[0401] C: Center axis

[0402] φ: azimuth

[0403] θo: polar angle

[0404] CP: Vertex

[0405] D1: Arrow (first direction)

[0406] D2: Arrow (second direction)

[0407] EP: Shining Point

[0408] MP: Observation point

Claims

1. A detector comprising: a light emitting element that emits light by irradiating the sample with a light beam and colliding with quanta emitted from the sample; and a plurality of light receiving elements, which receive the light generated by the light emitting element through a light receiving surface; The detector is characterized in that In a first direction intersecting the irradiation direction of the light beam, the light receiving surface is arranged at a position farther from the light beam than the light emitting element. The light receiving surface is arranged in a direction intersecting with the irradiation direction of the light beam. The detector forms: a first light path directing light toward the first direction; and A second optical path guides the light arriving via the first optical path toward the light receiving surface.

2. The detector according to claim 1, characterized in that The detector is provided with a light guide forming at least a portion of the second optical path.

3. The detector according to claim 1, characterized in that The detector includes a surface that reflects light arriving in a direction perpendicular to the irradiation direction of the light beam in a direction having a component facing in the opposite direction to the irradiation direction of the light beam.

4. The detector according to claim 1, characterized in that A plurality of the light receiving surfaces are arranged along the first direction.

5. The detector according to claim 1, characterized in that A plurality of the light emitting elements are arranged in the irradiation direction of the light beam.

6. The detector according to claim 2, characterized in that The light emitting elements are arranged in a plurality in the irradiation direction of the light beam. The plurality of light guides connected to the plurality of light emitting elements have portions that overlap with each other in the irradiation direction of the light beam.

7. The detector according to claim 2, characterized in that In the first direction, the light emitting element, the light guide, and the light receiving element are located on the same straight line.

8. The detector according to claim 2, characterized in that The width of the light guide is 1.5 times or less of the width of the light receiving surface.

9. The detector according to claim 1, wherein A plurality of the light emitting elements are arranged in a circumferential direction of the light beam.

10. The detector according to claim 2, characterized in that The light receiving surface of the light receiving element is bonded to the light guide.

11. The detector according to claim 1, characterized in that The light receiving element is a silicon photomultiplier tube.

12. The detector according to claim 1, characterized in that The light emitting element is arranged so that the incident angle of the quantum on the light emitting element is 30 degrees or less.

13. The detector according to claim 1, characterized in that an incident surface of the quantum incident on the light emitting element, and In the light emitting element, at least one of the surfaces on the opposite side to the incident surface in the irradiation direction of the light beam is inclined with respect to the first direction.

14. The detector according to claim 2, characterized in that In the light guide, a surface on the opposite side to the incident surface of the light emitting element in the irradiation direction of the light beam is inclined with respect to the first direction.

15. The detector according to claim 11, characterized in that The detector includes a plurality of silicon photomultiplier tubes. The operating voltage applied to the plurality of silicon photomultiplier tubes is the same.

16. The detector according to claim 2, characterized in that The light guide forms the first light path and the second light path.

17. The detector according to claim 1, characterized in that The first optical path is formed to include at least one of the following surfaces: a surface that reflects light having a component in the first direction and a component in a direction opposite to the irradiation direction of the light beam in a direction having a component in the first direction and a component in the irradiation direction of the light beam, and A surface that reflects light having a component in the first direction and a component in the irradiation direction of the light beam in a direction having the component in the first direction and a component in a direction opposite to the irradiation direction of the light beam.

18. A detector comprising: a light emitting element that emits light by irradiating the sample with a light beam and colliding with quanta emitted from the sample; and a plurality of light receiving elements, which receive the light generated by the light emitting element through a light receiving surface; The detector is characterized in that In a first direction intersecting the irradiation direction of the light beam, the light receiving surface is arranged at a position farther from the light beam than the light emitting element. The detector has a transparent area that transmits light quantum incident from the light emitting element toward the light receiving surface. The normal line of the light receiving surface forms an angle of less than 45 degrees with the first direction.

19. A measuring device, characterized in that: A detector according to claim 1.

20. The measuring device according to claim 19, characterized in that A plurality of detection elements are provided, each of which is composed of at least the light emitting element and the light receiving element and is capable of detecting signals individually. The measuring device generates an image based on information related to the energy or number of the quanta.

21. A charged particle beam device, characterized in that A detector according to claim 1.

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