Light guide, electron line detector, and charged particle device

Abstract

The present application provides a light guide capable of improving light guide efficiency of light generated by incidence of a detected line, an electron line detector, and a charged particle device. The electron line detector (1A) of the present application includes a light guide body (2) extending in one direction; a first phosphor layer (3) disposed on one end side of the light guide body (2) and generating first fluorescent light (L1) by incidence of a detected line (E); a second phosphor layer (4) extending from the one end side of the light guide body (2) toward the other end side and generating second fluorescent light (L2) by incidence of the first fluorescent light (L1); and a detection portion (5) disposed on the other end side of the light guide body (2) and optically coupled with the light guide body (2).

Description

Technical Field

[0001] This disclosure relates to photoconductors, electron wire detectors, and charged particle devices. Background Technology

[0002] Currently, detectors described in Patent Documents 1 and 2 are used as electron beam detectors, for example, in scanning electron microscopes. The detector described in Patent Document 1 includes a scintillator housing in a light guide that directs light generated by a scintillator to a light-receiving element. This housing is formed by a first surface opposite to the incident surface of the scintillator and a second surface opposite to the surface opposite to the incident surface of the scintillator. In this detector of Patent Document 1, an inclined surface is provided that reflects light incident from the second surface toward the interior of the light guide.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-183126

[0006] Patent Document 2: Japanese Patent Application Publication No. 2013-243055 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In the aforementioned photoconductor or electron line detectors, from the viewpoint of improving the detection accuracy of the detected line, it is necessary to improve the light guiding efficiency when the light generated by the incident light through the detected line reaches the detection unit. In the detector of Patent Document 1, the light emitted from both sides of the phosphor is also incident on the photoconductor by forming an inclined surface, but the improvement in light guiding efficiency is limited, and the shape of the photoconductor is also limited. In the detector of Patent Document 2, there is a problem that it is difficult to ensure the transparency of the ceramic phosphor.

[0009] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a light guide, electron wire detector and charged particle device that can improve the light guiding efficiency of light generated by incident light through the detected line.

[0010] Technical solutions for solving the problem

[0011] One aspect of the light guide disclosed herein includes: a light guide extending in one direction; a first phosphor layer disposed at one end of the light guide, which generates primary fluorescence upon incident light from a detected line; and a second phosphor layer extending from one end of the light guide toward the other end, which generates secondary fluorescence upon incident light from the primary fluorescence.

[0012] In this light guide, a second fluorophore layer, which generates secondary fluorescence due to the incident primary fluorescence generated in the first fluorophore layer, extends from one end of the light guide to the other. In this light guide, the primary fluorescence generated in the first fluorophore layer is guided through the light guide, and conversely, the secondary fluorescence generated in the second fluorophore layer due to the incident primary fluorescence is guided through either the light guide or the second fluorophore layer. Therefore, the light guiding efficiency of the light generated through the incident light of the detection line can be improved.

[0013] Alternatively, the second phosphor layer may extend further toward the other end of the light guide than the first phosphor layer. In this case, the incident efficiency of primary fluorescence into the second phosphor layer can be improved.

[0014] Alternatively, a second phosphor layer can extend from one end of the light guide to the other. In this case, the incident efficiency of primary fluorescence to the second phosphor layer can be improved, and in addition, secondary fluorescence can be efficiently guided through the second phosphor layer.

[0015] Alternatively, it may further include a third phosphor layer extending from one end of the light guide to the other, generating a third fluorescence through the incident second fluorescence. In this case, the third fluorescence generated in the third phosphor layer through the incident second fluorescence is guided through the light guide or the third phosphor layer. Therefore, the light guiding efficiency of the light generated through the incident light of the detected line can be further improved.

[0016] Alternatively, the first phosphor layer can be constructed from any of gadolinium oxysulfide, yttrium silicate, YAG, YAP, a phosphor with an InGaN / GaN quantum well structure layer, or ZnO. By employing such a first phosphor layer, high-speed response to the detected line can be achieved. Furthermore, primary fluorescence leakage generated in the first phosphor layer to the outside can be suppressed.

[0017] Alternatively, the light guide can be constructed using transparent glass, transparent resin, air, or a vacuum. In this case, the light guiding efficiency of the light guide can be ensured through a simple structure.

[0018] Alternatively, the light guide may have a first surface and a second surface located opposite the first surface. A first phosphor layer is disposed on the first surface side, and a second phosphor layer is disposed at least on the second surface side. On the second surface, an inclined surface is provided at one end of the light guide, which is inclined towards the first surface as it moves toward one end. By forming this inclined surface, the incident efficiency of primary fluorescence to the second phosphor layer can be improved. Furthermore, space-saving solutions can be sought when incorporating an electron beam detector with a light guide into a scanning electron microscope, etc.

[0019] Alternatively, the light guide may also include a reflective film that covers the edge of one end of the light guide in the second phosphor layer. This improves the incident efficiency of primary fluorescence into the second phosphor layer.

[0020] Alternatively, a through-hole may be provided at one end of the light guide, which penetrates the light guide, the first phosphor layer, and the second phosphor layer. This through-hole can be used, for example, as a hole to allow electron beams to pass through the sample when an electron beam detector with a light guide is installed in a scanning electron microscope.

[0021] Alternatively, it could be a light guide, also featuring a metal film covering the inner wall of the through-hole. In this case, by applying a potential to the metal film, the trajectory of the electron lines passing through the through-hole can be stabilized.

[0022] One aspect of the present disclosure is an electronic line detector comprising: the aforementioned light guide; and a detection unit disposed at the other end of the light guide body of the light guide and optically coupled to the light guide body.

[0023] In this electron beam detector, a second phosphor layer, which generates secondary fluorescence due to the incident primary fluorescence generated in the first phosphor layer, extends from one end of the light guide towards the other. In this detector, the primary fluorescence generated in the first phosphor layer is guided to the detection unit through the light guide, and the secondary fluorescence generated in the second phosphor layer due to the incident primary fluorescence is also guided to the detection unit through either the light guide or the second phosphor layer. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line can be improved.

[0024] One aspect of the present disclosure is a charged particle device comprising: an electron source that emits electron beams toward a sample; and a detector that detects charged particles generated in the sample by irradiation of the electron beams; the detector being configured by the aforementioned electron beam detector.

[0025] In the electron beam detector suitable for this charged particle device, a second phosphor layer, which generates secondary fluorescence due to the incident primary fluorescence generated in the first phosphor layer, extends from one end of the light guide towards the other. In this electron beam detector, the primary fluorescence generated in the first phosphor layer is guided to the detection unit through the light guide, and the secondary fluorescence generated in the second phosphor layer due to the incident primary fluorescence is also guided to the detection unit through either the light guide or the second phosphor layer. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line can be improved.

[0026] The effects of the invention

[0027] According to this disclosure, the light guiding efficiency of light generated in a phosphor can be improved. Attached Figure Description

[0028] Figure 1 The schematic diagrams showing the structure of the electron line detector of the first embodiment are as follows: (a) is a top view, (b) is a bottom view, and (c) is a cross-sectional view.

[0029] Figure 2 In the diagram, (a) is a schematic cross-sectional view showing the structure of the electron line detector of the second embodiment, and (b) is a schematic cross-sectional view showing the structure of the electron line detector of a modified example thereof.

[0030] Figure 3 In the diagram, (a) is a schematic cross-sectional view showing the structure of the electron line detector of the third embodiment, and (b) is a schematic cross-sectional view showing the structure of the electron line detector of a modified example thereof.

[0031] Figure 4 A schematic cross-sectional view illustrating the structure of the electron line detector of the fourth embodiment.

[0032] Figure 5 In the diagram, (a) and (b) are schematic cross-sectional views illustrating the structure of an electron line detector of a modified example of the fourth embodiment.

[0033] Figure 6 In the diagram, (a) and (b) are schematic cross-sectional views illustrating the structure of an electron line detector of another variation of the fourth embodiment.

[0034] Figure 7 A schematic diagram of the measurement system for the first effect confirmation test is shown.

[0035] Figure 8 In the figure, (a) and (b) are graphs showing the test results of the first effect confirmation test.

[0036] Figure 9 A schematic diagram of the measurement system for the second effect confirmation test is shown.

[0037] Figure 10 A graph showing the test results of the second effect confirmation test.

[0038] Figure 11 In the diagram, (a) and (b) are schematic cross-sectional views illustrating the structure of an electron line detector of another variation.

[0039] Figure 12 A schematic diagram illustrating the structure of a charged particle device made using the electron wire detector applicable to this disclosure. Detailed Implementation

[0040] Hereinafter, with reference to the accompanying drawings, a preferred embodiment of one aspect of the present disclosure, including a photoconductor, an electron wire detector, and a charged particle device, will be described in detail.

[0041] [First Implementation]

[0042] Figure 1 This is a schematic diagram illustrating the structure of the electron line detector according to the first embodiment. Figure 1 (a) is a top view. Figure 1 (b) is a bottom view. Figure 1 (c) is a cross-sectional view. This electron beam detector 1 is a device for detecting the detected beam E, such as electron beams or X-rays, and is configured to include a photoconductor G. The electron beam detector 1 is used, for example, in a charged particle device such as a general-purpose or semiconductor inspection scanning electron microscope, fluorescence microscope, electron beam detector, or radiation detector. The electron beam detector 1A of the first embodiment, as... Figure 1 (a)~ Figure 1 As shown in (c), it is configured to include a light guide G1 and a detection unit 5. The light guide G1 includes: a light guide 2, a first phosphor layer 3, and a second phosphor layer 4.

[0043] The light guide 2 is a portion that guides the fluorescence generated in the first phosphor layer 3 and the second phosphor layer 4 through the incident light of the detection line E toward the detection section 5. The light guide 2 is formed of a material that is transparent to the fluorescence generated in the first phosphor layer 3 and the second phosphor layer 4, such as transparent glass like quartz glass or borosilicate glass, or transparent resin like acrylic. The light guide 2 extends in one direction and has one end 2a and another end 2b in that direction. Figure 1 In the example, the light guide 2 is in the shape of a thin plate and has a first surface 2c with an axis orthogonal to the extension direction as the normal direction, and a second surface 2d located on the opposite side of the first surface 2c.

[0044] The first surface 2c is flat from one end of the light guide 2 to the other. The second surface 2d has an inclined surface K at one end of the light guide 2, which is inclined towards the first surface 2c as it moves toward that end. The inclination angle of the inclined surface K relative to the first surface 2c is, for example, between 10° and 60°. The portion of the second surface 2d at the other end, excluding the inclined surface K, is flat and parallel to the first surface 2c. At one end 2a of the light guide 2, there is a hole, for example, with a circular cross-section, which connects the first surface 2c and the inclined surface K of the second surface 2d in the thickness direction of the light guide 2.

[0045] The first phosphor layer 3 is a layer that generates primary fluorescence L1 when incident through the detected line. The first phosphor layer 3 can be constructed from, for example, any of the following: gadolinium oxysulfide, yttrium silicate, YAG (yttrium aluminum garnet), YAP (yttrium aluminum perovskite), a phosphor with an InGaN / GaN quantum well structure layer, or ZnO. The first phosphor layer 3 is disposed close to the first surface 2c side and extends within a certain range from one end of the light guide 2 towards the other end. Figure 1 In example (b), the first phosphor layer 3 is circular in shape when viewed from the top of the first surface 2c, and is concentrically arranged with the aperture of the light guide 2. The diameter of the first phosphor layer 3 is the same as the width of the light guide 2. At the center of the first phosphor layer 3, corresponding to the position of the aperture of the light guide 2, there is a circular aperture communicating with the aperture.

[0046] The second phosphor layer 4 is a layer that generates secondary fluorescence L2 through the incident primary fluorescence L1. The second phosphor layer 4 is, for example, a violet phosphor layer that generates secondary fluorescence L2 from light of the violet wavelength, and is formed, for example, by fluorescent acrylic or fluorescent glass. The second phosphor layer 4 is disposed at least adjacent to the second surface 2d side of the light guide 2, extending from one end of the light guide 2 toward the other end. Here, the second phosphor layer 4 extends further toward the other end of the light guide 2 than the first phosphor layer 3, extending further to the edge of the other end of the light guide 2. Figure 1 (a)~ Figure 1 In example (c), the second phosphor layer 4 is configured to completely cover the light guide 2. That is, the second phosphor layer 4 is configured with the same thickness as the first phosphor layer 3 in the portion of the first surface 2c of the light guide 2 excluding the first phosphor layer 3, the second surface 2d of the light guide 2, and the side surfaces 2e, 2e in the width direction of the light guide 2.

[0047] On one end side of the light guide 2, corresponding to the position of the second phosphor layer 4 covering the inclined surface K and the aperture of the light guide 2, a circular aperture communicating with the aperture is provided. Through these apertures, on one end side of the light guide 2, a through hole 6 is provided, through which the light guide 2, the first phosphor layer 3, and the second phosphor layer 4 pass in the thickness direction of the light guide 2. A metal film 7 is provided covering the inner wall of the through hole 6. The metal film 7, for example, when the electron beam detector 1A is applied to a scanning electron microscope, functions to stabilize the trajectory of electron beams passing through the through hole 6 by imparting a potential. Examples of materials constituting the metal film 7 include aluminum or silver.

[0048] The detection unit 5 is for detecting the light generated in the first phosphor layer 3 and the second phosphor layer 4. The detection unit 5 is disposed on the other end of the light guide 2 and is optically coupled to the light guide 2. Figure 1 (a)~ Figure 1 In example (c), the detection unit 5, for example, is constructed using a photomultiplier tube, and is optically coupled to both the light guide 2 and the second phosphor layer 4 at the other end of the light guide 2. The detection unit 5 outputs an output signal to an external device (not shown) corresponding to the intensity of the detected light.

[0049] In the electron line detector 1A with the above structure, the light guide 2 functions as a center light guide for the fluorescence generated in the first phosphor layer 3 and the second phosphor layer 4, and the second phosphor layer 4 functions as a side light guide for the fluorescence generated in the first phosphor layer 3 and the second phosphor layer 4. Specifically, in the electron line detector 1A, as... Figure 1 As shown in (c), if the detection line E is incident on the first phosphor layer 3, a primary fluorescence L1 corresponding to the incident amount of the detection line E is generated in the first phosphor layer 3. Most of the primary fluorescence L1 generated in the first phosphor layer 3 is incident on the light guide 2, and is repeatedly reflected in the light guide 2 while being incident on the detection unit 5.

[0050] The component of the primary fluorescence L1 generated in the first phosphor layer 3 that falls from the second surface 2d containing the inclined surface K to the outside of the light guide 2 is incident on the second phosphor layer 4, which is located on the opposite side of the first phosphor layer 3, separated by the light guide 2. If the primary fluorescence L1 is incident on the second phosphor layer 4, secondary fluorescence L2 corresponding to the incident amount of primary fluorescence L1 is generated in the second phosphor layer 4. Most of the secondary fluorescence L2 generated in the second phosphor layer 4 is repeatedly reflected within the second phosphor layer 4 and incident on the detection unit 5. In this embodiment, the component of the primary fluorescence L1 generated in the first phosphor layer 3 that falls to the outside of the first surface 2c and the second surface 2d during repeated reflection within the light guide 2 is also incident on the second phosphor layer 4. Through this component, the secondary fluorescence L2 generated in the second phosphor layer 4 is also repeatedly reflected within the second phosphor layer 4 and incident on the detection unit 5.

[0051] As explained above, in the electron line detector 1A, the second phosphor layer 4, which generates secondary fluorescence L2 due to the incident primary fluorescence L1 generated in the first phosphor layer 3, extends from one end of the light guide 2 towards the other end. In this electron line detector 1A, the primary fluorescence L1 generated in the first phosphor layer 3 is guided to the detection unit 5 through the light guide 2, and the secondary fluorescence L2 generated in the second phosphor layer 4 due to the incident primary fluorescence L1 is guided to the detection unit 5 through either the light guide 2 or the second phosphor layer 4. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line E can be improved.

[0052] In this embodiment, the second phosphor layer 4 extends further toward the other end of the light guide 2 than the first phosphor layer 3, extending from one end of the light guide 2 to the other end. This improves the incident efficiency of primary fluorescence L1 to the second phosphor layer 4, and also enables efficient guiding of secondary fluorescence L2 to the detection unit 5 through the second phosphor layer 4.

[0053] In this embodiment, the first phosphor layer 3 is constructed from any of gadolinium oxysulfide, yttrium silicate, YAG, YAP, a phosphor having an InGaN / GaN quantum well structure layer, or ZnO. This enables a high-speed response to the detected line E. Furthermore, leakage of primary fluorescence L1 generated in the first phosphor layer 3 to the outside can be suppressed.

[0054] In this embodiment, the light guide 2 is constructed from transparent glass such as quartz glass or borosilicate glass, or a transparent resin such as acrylic. This allows for efficient light guiding through the light guide 2 with a simple structure. Furthermore, in the case where a second phosphor layer 4 is used to cover the light guide 2 as in this embodiment, the light guide 2 can also be formed using air or a vacuum. In this case, the electron beam detector 1A becomes a hollow structure consisting of the first phosphor layer 3 and the second phosphor layer 4, thus further simplifying the structure and reducing its weight.

[0055] In this embodiment, the first phosphor layer 3 is disposed on the first surface 2c side of the light guide 2, and the second phosphor layer 4 is disposed on the second surface 2d side of the light guide 2. Furthermore, on the second surface 2d, an inclined surface K is provided at one end of the light guide 2, which is inclined towards the first surface 2c as it moves toward that end. By forming this inclined surface K, the incident efficiency of primary fluorescence L1 to the second phosphor layer 4 can be improved. In addition, space saving is possible when incorporating the electron beam detector 1A into a scanning electron microscope, etc.

[0056] In this embodiment, a through-hole 6 is provided at one end of the light guide 2, through which the light guide 2, the first phosphor layer 3, and the second phosphor layer 4 pass. This through-hole 6 can be used, for example, as a hole through which electron beams pass towards the sample when the electron beam detector 1A is installed in a scanning electron microscope. Furthermore, in this embodiment, a metal film 7 is provided covering the inner wall of the through-hole 6. In this case, by applying a potential to the metal film 7, the trajectory of the electron beams passing through the through-hole 6 can be stabilized.

[0057] [Second Implementation]

[0058] Figure 2 (a) is a schematic cross-sectional view showing the structure of the electron line detector according to the second embodiment. Furthermore, Figure 2(b) is a schematic cross-sectional view showing the structure of an electron line detector of a modified example. Although the through hole 6 is omitted from these figures for the sake of simplification, the presence of the through hole 6 is the same as in the first embodiment. On the other hand, electron line detectors 1B and 1C shown in the same figure differ from the first embodiment in that the second phosphor layer 4 does not extend to the edge of the other end of the light guide 2.

[0059] Figure 2 The electron line detector 1B shown in (a) has a light guide G2. In the light guide G2, the extension length of the second phosphor layer 4 on the first surface 2c side and the second surface 2d side of the light guide 2 is less than half the extension length of the first phosphor layer 3. Figure 2 In example (a), in the extending direction of the light guide 2, the edge of the other end 2b side of the second phosphor layer 4 on the first surface 2c side is located closer to the other end 2b side than the edge of the other end 2b side of the second phosphor layer 4 on the second surface 2d side. The light guide 2 is located between the second phosphor layer 4 on the first surface 2c side and the detection part 5, and between the second phosphor layer 4 on the second surface 2d side and the detection part 5.

[0060] In addition, a reflective film 10 is provided on the edge of one end of the light guide 2 covering the second phosphor layer 4 in the light guide G2. Figure 2 In example (a), a reflective film 10 is provided to cover the inclined surface K of the light guide 2 (except for the through hole 6). The reflective film 10, for example, is formed of a metal such as Al, and reflects the primary fluorescence and secondary fluorescence L2 that are directed toward one end of the light guide 2 toward the other end.

[0061] Figure 2 The electron line detector 1C shown in (b) further differs from the electron line detector 1B in that the second phosphor layer 4 on the first surface 2c side of the light guide 2 is omitted. The electron line detector 1C has a light guide G3. In the light guide G3, the first phosphor layer 3 on the first surface 2c side is disposed on the first surface 2c, while the second phosphor layer 4 on the second surface 2d side is disposed in a manner that is coplanar with the second surface 2d.

[0062] In these electron line detectors 1B and 1C, primary fluorescence L1 generated in the first phosphor layer 3 is guided to the detection unit 5 via the light guide 2. Furthermore, secondary fluorescence L2 generated in the second phosphor layer 4 by the incident primary fluorescence L1 is also guided to the detection unit 5 via the light guide 2. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line E can be improved. Furthermore, in electron line detectors 1B and 1C, the incident efficiency of primary fluorescence L1 to the second phosphor layer 4 can be improved by using a reflective film 10 covering the edge of one end of the light guide 2 of the second phosphor layer 4. In this embodiment, the reflective film 10 covers the entire inclined surface K of the light guide 2, thus also improving the light guiding efficiency of the secondary fluorescence L2 generated in the second phosphor layer 4. Additionally, this reflective film 10 can also be applied to the light guide G1 of the first embodiment.

[0063] [Third Implementation]

[0064] Figure 3 (a) is a schematic diagram illustrating the structure of the electron line detector according to the third embodiment. Furthermore, Figure 3 (b) is a schematic cross-sectional view showing the structure of an electron line detector, illustrating a modified example thereof. Figure 2 Similarly, for the sake of simplicity, the illustration of the through hole 6 is omitted. The electron line detectors 1D and 1E shown in the figure differ from the first embodiment in that the second surface 2d of the light guide 2 does not have an inclined surface K. That is, in electron line detectors 1D and 1E, the light guide 2 is a cuboid shape extending in one direction.

[0065] Figure 3 The electron line detector 1D shown in (a) has a light guide G4. Similar to the first embodiment, a second phosphor layer 4 is provided in the light guide G4 to completely cover the light guide 2. That is, the second phosphor layer 4 is formed on the portion of the first surface 2c of the light guide 2 excluding the first phosphor layer 3, on the second surface 2d of the light guide 2, and on the side surface (not shown) in the width direction of the light guide 2. A reflective film 10 is provided on the end face 2f at one end of the light guide 2. Figure 3 In example (a), the reflective film 10 is arranged such that it covers the end face 2f of one end of the light guide 2 and the edge of one end of the light guide 2 of the first phosphor layer 3 and the second phosphor layer 4.

[0066] Figure 3The structure of the second phosphor layer 4 in the electron line detector 1E shown in (b) is further different from that in the electron line detector 1D. The electron line detector 1E has a light guide G5. In the light guide G5, the second phosphor layer 4 is not provided on the first surface 2c side of the light guide 2, and the extension length of the second phosphor layer 4 on the second surface 2d side of the light guide 2 is the same as the extension length of the first phosphor layer 3. In the extension direction of the light guide 2, the edge of the other end 2b side of the second phosphor layer 4 on the first surface 2c side and the edge of the other end 2b side of the second phosphor layer 4 on the second surface 2d side are at the same position. In the light guide G5, the first phosphor layer 3 on the first surface 2c side is provided on the first surface 2c, while the second phosphor layer 4 on the second surface 2d side is provided in a manner that is coplanar with the second surface 2d.

[0067] In these electron line detectors 1D and 1E, the primary fluorescence L1 generated in the first phosphor layer 3 is guided to the detection unit 5 through the light guide 2. Furthermore, the secondary fluorescence L2 generated in the second phosphor layer 4 by the incident primary fluorescence L1 is guided to the detection unit 5 through either the light guide 2 or the second phosphor layer 4. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line E can be improved. Furthermore, in electron line detectors 1D and 1E, the incident efficiency of the primary fluorescence L1 to the second phosphor layer 4 can be improved by using a reflective film 10 covering the edge of one end of the light guide 2 of the second phosphor layer 4. In this embodiment, the reflective film 10 covers the end face 1f of one end of the light guide 2 and the edge of one end of the light guide 2 of the first phosphor layer 3. Therefore, the incident efficiency of the primary fluorescence L1 to the second phosphor layer 4 can be further improved, and the light guiding efficiency of the secondary fluorescence L2 generated in the second phosphor layer 4 can also be improved.

[0068] [Fourth Implementation]

[0069] Figure 4 This is a schematic cross-sectional view illustrating the structure of the electron line detector according to the fourth embodiment. Furthermore, Figure 5 and Figure 6 This is a schematic cross-sectional view illustrating the structure of a modified electron line detector. Electron line detectors 1F to 1J shown in the figure differ from the first embodiment in that the inclined surface K is not provided on the second surface 2d of the light guide 2. Furthermore, in electron line detectors 1F to 1J, the light guide 2 is in the shape of a cylinder extending in one direction.

[0070] like Figure 4 As shown, the electron line detector 1F has a light guide G6. A first phosphor layer 3 is provided on the entire surface of the end face 2f on one end side of the light guide 2 in the light guide G6. A second phosphor layer 4 is provided such that it covers the entire peripheral surface of the light guide 2 and the entire peripheral surface of the first phosphor layer 3.

[0071] Figure 5 The difference between electron line detector 1G and electron line detector 1F shown in (a) is that a reflective film 10 is added to the structure of electron line detector 1F. Electron line detector 1G has a light guide G7. In the light guide G7, the reflective film 10 is disposed on one end side of the light guide 2, covering the edge of one end side of the light guide 2 of the first phosphor layer 3 and the second phosphor layer 4. A portion of the reflective film 10 also extends to the peripheral surface of the second phosphor layer 4. The edge of the other end 2b of the extended portion 10a of the reflective film 10 is located closer to the other end 2b side than the edge of the other end 2b side of the first phosphor layer 3.

[0072] Figure 5 The difference between electron line detector 1H and electron line detector 1F shown in (b) is that the second phosphor layer 4 does not extend to the edge of the other end side of the light guide 2. Electron line detector 1H has a light guide G8. In the light guide G8, the edge of the other end 2b side of the second phosphor layer 4 is located closer to the other end 2b side than the edge of the other end 2b side of the first phosphor layer 3. The edge of the other end 2b of the protruding portion 10a of the reflective film 10 is located closer to the other end 2b side than the edge of the other end 2b side of the first phosphor layer 3. Furthermore, the edge of the other end 2b of the protruding portion 10a of the reflective film 10 is located closer to the other end 2b side than the edge of the other end 2b side of the second phosphor layer 4. That is, the protruding portion 10a of the reflective film 10 covers the entire circumference of the second phosphor layer 4.

[0073] Figure 6 The difference between electron detector 1I and electron detector 1F shown in (a) is that the edge of one end 2a of the second phosphor layer 4 is a sloping surface Ka. Electron detector 1I has a light guide G9. In the light guide G9, at the portion where the sloping surface Ka is formed, the thickness of the second phosphor layer 4 gradually decreases towards the end of the light guide 2. The reflective film 10 includes the sloping surface Ka and is disposed such that it covers the first phosphor layer 3 and the second phosphor layer 4. Similar to the light guide G8, the protruding portion 10a of the reflective film 10 covers the entire peripheral surface of the second phosphor layer 4.

[0074] Figure 6The electron detector 1J shown in (b) is similar to the electron detector 1I, but differs from the electron detector 1F in that the edge of one end 2a of the second phosphor layer 4 is a sloping surface Ka. The electron detector 1J has a light guide G10. In the electron detector 1J, the thickness of the second phosphor layer 4 gradually decreases towards the end of the light guide 2 in the portion forming the sloping surface Ka. Furthermore, the second phosphor layer 4 is provided in a manner that covers the entire peripheral surface of the light guide 2 and the entire peripheral surface of the first phosphor layer 3. The reflective film 10 includes the sloping surface Ka, which is provided in a manner that covers the entire first phosphor layer 3 and a portion of the second phosphor layer 4 (the portion on the side of the first phosphor layer 3).

[0075] In these electron line detectors 1F to 1J, primary fluorescence L1 generated in the first phosphor layer 3 is guided to the detection unit 5 via the light guide 2. Furthermore, secondary fluorescence L2 generated in the second phosphor layer 4 by the incident primary fluorescence L1 is guided to the detection unit 5 via either the light guide 2 or the second phosphor layer 4. Therefore, the light guiding efficiency of the light generated by the incident light through the detected line E can be improved. Furthermore, in electron line detectors 1G to 1J, the incident efficiency of primary fluorescence L1 to the second phosphor layer 4 can be improved by using a reflective film 10 covering the edge of one end of the light guide 2 of the second phosphor layer 4. In this embodiment, the reflective film 10 covers the first phosphor layer 3, and the extended portion 10a of the reflective film 10 covers the entire peripheral surface of the second phosphor layer 4. This further improves the incident efficiency of primary fluorescence L1 to the second phosphor layer 4, and also improves the light guiding efficiency of secondary fluorescence L2 generated in the second phosphor layer 4.

[0076] [Effect Confirmation Test]

[0077] Next, the effectiveness verification test of the photoconductor and electron wire detector disclosed herein will be described.

[0078] Figure 7 A schematic diagram illustrating the measurement system for the first effect confirmation test is provided. The first effect confirmation test is a test in which, upon learning of the photoconductor and electron wire detector of this disclosure, the relationship between the material of the light guide and the light guiding efficiency is investigated. For example... Figure 7 As shown, the measurement system 101A for the first effect confirmation test includes: a light guide 102 extending in one direction; a phosphor layer 103 disposed on one end side of the light guide 102, closely attached to the first surface side of the light guide 102; and a detection unit 105 disposed on the other end side of the light guide.

[0079] In Experiment 1, the light guide 102 was constructed using an acrylic fluorescent plate, and in Experiment 2, the light guide 102 was constructed using quartz. The acrylic fluorescent plate was configured as either a green fluorescent plate that generates secondary fluorescence using light in the green region or a purple fluorescent plate that generates secondary fluorescence using light in the violet region. The phosphor layer 103 was constructed using a high-speed GaN phosphor, and the detection unit 105 was constructed using a photomultiplier tube. The light guide 102, phosphor layer 103, and detection unit 105 were covered by a light-shielding fixture 106, except for the incident position of the detected line E. For Experiments 1 and 2, the current value of the signal output from the detection unit 105 based on the incident light on the detected line E was measured.

[0080] Figure 8 (a) and Figure 8 (b) is a graph showing the measurement results of the first effect confirmation test. In the same graph, the accelerating voltage of the test line is shown on the horizontal axis, and the current value of the detection section is shown on the vertical axis. As can be seen from the results shown in the same graph, in both the case where the light guide 102 is a green fluorescent plate and the case where the light guide 102 is a purple fluorescent plate, the current value of the detection section 105 for the test line E of the same intensity is higher than that in Test Example 1 and Test Example 2. From this result, it can be concluded that even if the primary fluorescence generated in the phosphor layer is directly incident on the fluorescent plate (without passing through a light guide made of quartz or the like), the light guiding efficiency cannot be increased.

[0081] In the first effect confirmation test, the reason for the difference in detection results when the light guide 102 is quartz and when it is an acrylic fluorescent plate is believed to be due to the diffusion of the detection line E incident on the light guide 102. Specifically, in this measurement system 101A, the primary fluorescence generated in the phosphor layer 103 by the incident detection line E is diffused light, which is incident on the light guide 2 from the generation position with a diffusion degree of approximately 180°. When the light guide 102 is an acrylic fluorescent plate, the primary fluorescence incident from the phosphor layer 103 is re-emitted within the acrylic fluorescent plate, becoming secondary fluorescence. However, the diffusion degree of the secondary fluorescence is almost the same when the light guide 102 is quartz and when the primary fluorescence incident from the phosphor layer 103 on the light guide 102. Therefore, it is speculated that the total amount of light guided to the detection unit 105 is reduced because the transmittance of the acrylic fluorescent plate is lower than that of quartz.

[0082] Figure 9This diagram illustrates the measurement system for the second effect confirmation test. As shown, the measurement system 101B for the second effect confirmation test differs from the measurement system 101A for the first effect confirmation test in that side light guides 104 are provided on both the first and second surfaces of the light guide 102. The side light guide 104 on the first surface extends adjacent to the phosphor layer 103 to the edge of the other end of the light guide 102, and the side light guide 104 on the second surface extends from the edge of one end of the light guide 102 to the edge of the other end. In both the embodiment and the comparative example, the light guide 102 is constructed of quartz. On the other hand, in the embodiment, the side light guide 104 is constructed of a fluorescent acrylic plate, while in the comparative example, the side light guide 104 is constructed of quartz.

[0083] Figure 10 This is a schematic diagram of the test results for the second effect confirmation test. In the same diagram, [the results are shown in the original text]. Figure 8 (a) and Figure 8 Similarly, in (b), the accelerating voltage of the detected line is shown on the horizontal axis, and the current value of the detection unit is shown on the vertical axis. Figure 10 The results show that, in the embodiment, compared to the comparative example, the average current value of the detection section 105 for the same intensity of the detected line E is 40% higher. From these results, it can be observed that, by guiding the primary fluorescence generated in the phosphor layer 103 through a light guide 102 made of quartz or the like, and further guiding the secondary fluorescence generated from the primary fluorescence through a side light guide 104 different from the light guide 102, the light guiding efficiency can be increased.

[0084] In this measurement system 101B, the primary fluorescence generated in the phosphor layer 103 by the incident light of the detection line E is diffused light, which is incident on the light guide 102 from the generation position with a diffusion of approximately 180°. In the comparative example, both the light guide 102 and the side light guide 104 are made of quartz. Therefore, it is assumed that the component of the primary fluorescence generated in the phosphor layer 103 below a certain angle (critical angle) is emitted to the outside through the light guide 102 and the side light guide 104 on the opposite side of the phosphor layer 103, and only a portion of the primary fluorescence is retained in the total amount of light guided to the detection unit 105.

[0085] In contrast, in this embodiment, a component of the primary fluorescence generated in the phosphor layer 103 at an angle (critical angle) below this angle is incident on the side light guide 104 on the opposite side of the phosphor layer 103, thereby generating secondary fluorescence. It is believed that because this secondary fluorescence is guided by the side light guide 104, the total amount of light guided to the detection unit 105 is increased. Furthermore, in this embodiment, a portion of the secondary fluorescence is guided by the light guide 102; in addition, a portion of the primary fluorescence guided by the light guide 102 is incident on the side light guide 104 on the phosphor layer 103 side, thus generating secondary fluorescence. Therefore, it is believed that the total amount of light guided to the detection unit 105 is further increased.

[0086] [Variation Example]

[0087] This disclosure is not limited to the embodiments described above. For example, in the embodiments described above, the light guide G includes a first phosphor layer 3 and a second phosphor layer 4, but the light guide G may also have, in addition to these phosphor layers, the following: Figure 11 (a) and Figure 11 As shown in (b), the device further includes a third phosphor layer 11 that generates third fluorescence through the incident second fluorescence. In this case, by extending the third phosphor layer 11 from one end of the light guide 2 toward the other end, the third fluorescence generated in the third phosphor layer 11 is guided to the detection unit 5 through the light guide 2 or the third phosphor layer 11. Therefore, the light guiding efficiency of the light generated through the incident line E can be further improved.

[0088] The light guide G may also include, in addition to the third phosphor layer 11, a fourth phosphor layer 12 that generates fourth fluorescence through the incidence of third fluorescence. For example... Figure 11 As shown in (a), in addition to the structure of the photoconductor G11 constituting the electron line detector 1K, a third phosphor layer 11 is provided to cover the outer side of the second phosphor layer 4, and a fourth phosphor layer 12 is provided to cover the outer side of the third phosphor layer 11. Figure 11 As shown in (b), in addition to the structure of the photoconductor G12 constituting the electron line detector 1L, a third phosphor layer 11 is provided in a manner that covers the outer side of the second phosphor layer 4, and a fourth phosphor layer 12 is provided in a manner that covers the outer side of the third phosphor layer 11.

[0089] When high-order phosphor layers are provided, preferably, the wavelength of the nth fluorescence generated by the nth order (n is an integer) phosphor layer is close to the excitation center wavelength of the (n+1)th order phosphor layer. For example, if the second phosphor layer 4 is a violet phosphor layer that generates second-order fluorescence using light in the violet region, the third phosphor layer 11 is preferably a green phosphor layer that generates third-order fluorescence using light in the green region, and the fourth phosphor layer 12 is preferably a red phosphor layer that generates fourth-order fluorescence using light in the red region.

[0090] Figure 12 This is a schematic diagram illustrating the structure of a charged particle device made using the electron beam detector applicable to this disclosure. The charged particle device 21 shown in the figure is configured as a scanning electron microscope. The charged particle device 21 is configured to include: an electron source 22 that emits electron beams e1 toward a sample S; and a detector 23 that detects charged particles generated in the sample S by irradiation with electron beams e1. The detector 23 is configured with a detector 23A that detects reflected electrons e2 from the sample S, and a detector 23B that detects secondary electrons e3 from the sample S.

[0091] Detector 23A is configured, for example, by the electron line detector 1A described above, and detector 23B is configured, for example, by the electron line detector 1F described above. Electron line detector 1F is disposed within the cylindrical member 24, closer to the sample S than electron line detector 1A. Electron lines e1 emitted from electron source 22 are deflected by scanning coil 25, performing scanning of the sample S by electron lines e1. After passing through scanning coil 25, electron lines e1, after passing through objective lens 26 which is composed of a magnetic circuit and excitation coil, pass through through-hole 6 of electron line detector 1A and irradiate the sample S.

[0092] Irradiation by electron beam e1 generates reflected electrons e2 and secondary electrons e3 in sample S. Reflected electron e2 is incident on electron beam detector 1A, causing the first phosphor layer 3 to emit light. The primary fluorescence L1 generated in the first phosphor layer 3 and the secondary fluorescence L2 generated in the second phosphor layer 4 are detected by detection unit 5 and converted into an output signal corresponding to the intensity of the detected light. Secondary electrons e3 are incident on electron beam detector 1F, similarly causing the first phosphor layer 3 to emit light. The primary fluorescence L1 generated in the first phosphor layer 3 and the secondary fluorescence L2 generated in the second phosphor layer 4 are detected by detection unit 5 and converted into an output signal corresponding to the intensity of the detected light.

[0093] In this charged particle device 21, in the electron line detectors 1A and 1F constituting detectors 23A and 23B, primary fluorescence L1 generated in the first phosphor layer 3 is guided to the detection unit 5 through the light guide 2. Furthermore, secondary fluorescence L2 generated in the second phosphor layer 4 by the incident primary fluorescence L1 is guided to the detection unit 5 through either the light guide 2 or the second phosphor layer 4. Therefore, the light guiding efficiency of light generated by the incident reflected electrons e2 and secondary electrons e3, which are the detected lines, can be improved.

[0094] [Explanation of Symbols]

[0095] 1 (1A~1L)…Electron line detector, G (G1~G12)…Light guide, 2…Light guide body, 2c…First surface, 2d…Second surface, 3…First phosphor layer, 4…Second phosphor layer, 5…Detection section, 6…Through hole, 7…Metal film, 10…Reflective film, 11…Third phosphor layer, 12…Fourth phosphor layer, 21…Charged particle device, 22…Electron source, 23…Detector, E…Detected line, K…Sloping surface, L1…First fluorescence, L2…Second fluorescence, e1…Electron line, e2…Reflected electron, e3…Secondary electron, S…Sample.

Claims

1. An optical guide, comprising: A light guide extending in one direction; A first phosphor layer, disposed at one end of the light guide, generates primary fluorescence upon incident light from the detected line; and The second phosphor layer extends from one end of the light guide toward the other end in such a way that the primary fluorescence generated in the first phosphor layer can be incident on the second phosphor layer, thereby generating secondary fluorescence through the incident primary fluorescence.

2. The optical guide according to claim 1, wherein, The second phosphor layer extends further toward the other end of the light guide than the first phosphor layer.

3. The optical guide according to claim 1, wherein, The second phosphor layer extends from one end of the light guide to the other end.

4. The optical guide according to claim 2, wherein, The second phosphor layer extends from one end of the light guide to the other end.

5. The optical guide according to any one of claims 1 to 4, wherein, It also includes a third phosphor layer that extends from one end of the light guide toward the other end, generating a third fluorescence through the incident second fluorescence.

6. The optical guide according to any one of claims 1 to 4, wherein, The first phosphor layer is composed of any one of gadolinium oxysulfide, yttrium silicate, YAG, YAP, a phosphor having an InGaN / GaN quantum well structure layer, or ZnO.

7. The optical guide according to any one of claims 1 to 4, wherein, The light guide is constructed using transparent glass, transparent resin, air, or a vacuum.

8. The optical guide according to any one of claims 1 to 4, wherein, The light guide has: a first surface and a second surface located on the opposite side of the first surface. The first phosphor layer is disposed on the first surface side. The second phosphor layer is at least disposed on the second surface side. On the second surface, an inclined surface is provided at one end of the light guide, which is inclined in a manner that approaches the first surface as it moves toward the one end.

9. The optical guide according to any one of claims 1 to 4, wherein, It also includes: a reflective film that covers the edge of one end of the light guide of the second phosphor layer.

10. The optical guide according to any one of claims 1 to 4, wherein, A through hole is provided at one end of the light guide, which penetrates the light guide, the first phosphor layer and the second phosphor layer.

11. The optical guide according to claim 10, wherein, It also includes a metal film covering the inner wall of the through hole.

12. An electron beam detector, comprising: The optical guide according to any one of claims 1 to 11; and A detection unit is disposed at the other end of the light guide body of the light guide and is optically coupled to the light guide body.

13. A charged particle device comprising: An electron source that emits electron beams toward the sample; and A detector that detects charged particles generated in the sample by irradiation with the electron beam; The detector is configured using the electron line detector of claim 12.

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