Electron beam detection device and transmission electron microscope

Abstract

This electron beam detection device comprises: an image sensor; a first fiber optics plate disposed on the image sensor; a second fiber optics plate disposed on the first fiber optics plate; a scintillator layer disposed on the second fiber optics plate; and an immersion oil layer disposed between the first fiber optics plate and the second fiber optics plate. The immersion oil layer contacts a light output surface of the second fiber optics plate and a light input surface of the first fiber optics plate.

Description

Electron beam detector and transmission electron microscope

[0001] The present disclosure relates to an electron beam detection device and a transmission electron microscope.

[0002] Patent Document 1 describes an electron beam detection device applicable to a transmission electron microscope, which includes an image sensor, a first fiber optic plate disposed on the image sensor, a second fiber optic plate disposed on the first fiber optic plate, a scintillator layer disposed on the second fiber optic plate, and an optical coupling gel disposed between the first fiber optic plate and the second fiber optic plate. In the electron beam detection device described in Patent Document 1, when the scintillator layer deteriorates, the image sensor can be left together with the first fiber optic plate, and the scintillator layer and the second fiber optic plate can be replaced with new ones.

[0003] US Patent Application Publication No. 2006 / 0124858

[0004] In the electron beam detection device described in Patent Document 1, a thixotropic gel that does not exhibit fluidity when no shear stress is applied is considered to be a suitable example of the optical coupling gel. However, if such an optical coupling gel is placed between the first fiber optic plate and the second fiber optic plate, the distance between the light output surface of the second fiber optic plate and the light input surface of the first fiber optic plate will not decrease even if the space inside the housing of the transmission electron microscope is evacuated, which may result in a decrease in resolution in the electron beam detection results.

[0005] Therefore, an object of the present disclosure is to provide an electron beam detection device that can replace the scintillator layer with a new one while leaving the image sensor intact, and that can suppress a decrease in resolution in the electron beam detection results, and a transmission electron microscope equipped with such an electron beam detection device.

[0006] An electron beam detection device according to one aspect of the present disclosure is [1] "an electron beam detection device comprising an image sensor, a first fiber optic plate disposed on the image sensor, a second fiber optic plate disposed on the first fiber optic plate, a scintillator layer disposed on the second fiber optic plate, and an immersion oil layer disposed between the first fiber optic plate and the second fiber optic plate, wherein the immersion oil layer is in contact with a light output surface of the second fiber optic plate and a light input surface of the first fiber optic plate."

[0007] In the above-described electron beam detection device, an immersion oil layer is disposed between the first fiber optic plate on the image sensor side and the second fiber optic plate on the scintillator layer side. This allows, for example, if the scintillator layer or the second fiber optic plate deteriorates, to replace the scintillator layer and the second fiber optic plate with new ones while leaving the image sensor together with the first fiber optic plate. Furthermore, in the above-described electron beam detection device, the immersion oil layer contacts the light output surface of the second fiber optic plate and the light input surface of the first fiber optic plate. This allows, for example, when the surrounding space is evacuated, the fluidity of the immersion oil layer to optically contact the light output surface of the second fiber optic plate and the light input surface of the first fiber optic plate via the immersion oil layer, thereby enabling accurate transmission of an image from the light output surface of the second fiber optic plate to the light input surface of the first fiber optic plate. Therefore, the above-described electron beam detection device allows the scintillator layer to be replaced with a new one while leaving the image sensor, and suppresses degradation of the resolution of the electron beam detection results.

[0008] The electron beam detection device according to one aspect of the present disclosure may be [2] "the electron beam detection device according to the above [1], in which the thickness of the immersion oil layer is 3 μm or less." With this electron beam detection device, an image can be transmitted with higher accuracy from the light output surface of the second fiber optic plate to the light input surface of the first fiber optic plate.

[0009] An electron beam detection device according to one aspect of the present disclosure may be [3] "the electron beam detection device according to [1] or [2] above, in which the thickness of the second fiber optic plate is greater than the thickness of the first fiber optic plate." With this electron beam detection device, electron beams reaching the immersion oil layer are more likely to be attenuated by the second fiber optic plate than when the thickness of the second fiber optic plate is smaller than the thickness of the first fiber optic plate, thereby suppressing deterioration of the image sensor and the first fiber optic plate due to irradiation with electron beams.

[0010] An electron beam detection device according to one aspect of the present disclosure may be [4] "the electron beam detection device according to any one of [1] to [3] above, wherein an outer edge of the second fiber optic plate is located outside an outer edge of the first fiber optic plate when viewed in the thickness direction of the scintillator layer." According to this electron beam detection device, by reducing the size of the first fiber optic plate when viewed in the thickness direction of the scintillator layer, a region other than the light receiving region of the image sensor (e.g., a circuit region) can be exposed, and by increasing the size of the second fiber optic plate when viewed in the thickness direction of the scintillator layer, deterioration of the region (e.g., the circuit region) due to irradiation with an electron beam can be suppressed.

[0011] The electron beam detection device according to one aspect of the present disclosure may be [5] "the electron beam detection device according to any one of [1] to [4] above, further comprising an optically transparent adhesive layer disposed between the image sensor and the first fiber optic plate, the first fiber optic plate being adhered to the image sensor by the adhesive layer." This electron beam detection device can suppress misalignment of the first fiber optic plate with respect to the image sensor.

[0012] The electron beam detection device according to one aspect of the present disclosure may be [6] "the electron beam detection device according to any one of the above [1] to [5], in which the scintillator layer is a layer containing GOS:Pr." With this electron beam detection device, the scintillator layer, which is relatively susceptible to deterioration, can be replaced with a new one together with the second fiber optic plate.

[0013] The electron beam detection device according to one aspect of the present disclosure may be [7] "the electron beam detection device according to any one of [1] to [6] above, further including a transparent conductive film disposed between the second fiber optic plate and the scintillator layer." According to this electron beam detection device, charging breakdown of the scintillator layer can be suppressed by grounding the transparent conductive film. Furthermore, reflection of light emitted from the scintillator layer in response to incidence of electron beams by the transparent conductive film is suppressed, thereby suppressing a decrease in resolution in the electron beam detection results.

[0014] An electron beam detection device according to one aspect of the present disclosure may be [8] "the electron beam detection device according to the above [7], in which, when viewed from the thickness direction of the scintillator layer, the outer edge of the transparent conductive film is located outside the outer edge of the scintillator layer." According to this electron beam detection device, it becomes easier to bring some kind of member into contact with the outer edge region of the transparent conductive film, so that the transparent conductive film can be easily and reliably grounded.

[0015] A transmission electron microscope according to one aspect of the present disclosure may be [9] "a transmission electron microscope comprising the electron beam detection device according to any one of [1] to [8] above, an electron beam source, and a sample support unit arranged between the electron beam source and the electron beam detection device." With this transmission electron microscope, as described above, in the electron beam detection device, it is possible to replace the scintillator layer with a new one while leaving the image sensor intact, and it is possible to suppress a decrease in resolution in the detection results of the electron beam.

[0016] According to the present disclosure, it is possible to provide an electron beam detection device that can replace the scintillator layer with a new one while leaving the image sensor intact, and that can suppress a decrease in resolution in the electron beam detection results, and a transmission electron microscope equipped with such an electron beam detection device.

[0017] Fig. 1 is a diagram showing the configuration of an example transmission electron microscope. Fig. 2 is a cross-sectional view of the electron beam detection device shown in Fig. 1. Fig. 3 is a diagram showing the light utilization efficiency of a comparative example and Example 1. Fig. 4 is a diagram showing the MTFs of Examples 2 and 3 and a reference example. Fig. 5 is a diagram showing the MTFs of Examples 4 and 5 and a reference example.

[0018] An example of the present disclosure will now be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0019] As shown in FIG. 1 , a transmission electron microscope 10 includes a housing 11, an electron beam source 12, a plurality of lens coils 13, a sample support 14, a plurality of lens coils 15, and an electron beam detection device 1. The electron beam source 12, the plurality of lens coils 13, the sample support 14, the plurality of lens coils 15, and the electron beam detection device 1 are arranged in this order along a direction A from one side in the direction A. The direction A is, for example, a vertical direction, and the one side in the direction A is, for example, an upper side. In the following description, the one side in the direction A (the upper side in FIG. 1 ) will be simply referred to as "the one side," and the other side in the direction A (the lower side in FIG. 1 ) will be simply referred to as "the other side."

[0020] The housing 11 houses an electron beam source 12, multiple lens coils 13, a sample support 14, multiple lens coils 15, and an electron beam detection device 1. The electron beam source 12 outputs an electron beam EB. The electron beam source 12 is, for example, an electron gun that emits the electron beam EB. The sample support 14 is disposed between the electron beam source 12 and the electron beam detection device 1. The sample support 14 supports a sample S. The sample support 14 is, for example, a sample holder that holds the sample S. The electron beam detection device 1 detects the electron beam EB that has transmitted through the sample S. The multiple lens coils 13 focus the electron beam EB output from the electron beam source 12 on a predetermined region of the sample S. The multiple lens coils 15 focus the electron beam EB that has transmitted through the sample S on a predetermined region of a scintillator layer (details will be described later) of the electron beam detection device 1. The space within the housing 11 is evacuated when an electron beam transmission image of the sample S is acquired.

[0021] 2 , the electron beam detection device 1 includes an image sensor 2, an adhesive layer 3, a first FOP (first fiber optic plate) 4, an immersion oil layer 5, a second FOP (second fiber optic plate) 6, a transparent conductive film 7, and a scintillator layer 8. The electron beam detection device 1 is supported by a support member 91. The support member 91 is attached to the wall portion 111 so as to cover the opening 111a of the wall portion 111, thereby placing the electron beam detection device 1 in the space within the housing 11 via the opening 111a of the wall portion 111. The wall portion 111 is a wall portion that constitutes a part of the housing 11 of the transmission electron microscope 10. The wall portion 111 and the support member 91 are formed of, for example, metal.

[0022] The image sensor 2 is disposed on one surface 92a of the wiring substrate 92. A plurality of terminals of the image sensor 2 are electrically connected to a plurality of wires of the wiring substrate 92. The image sensor 2 and the wiring substrate 92 are housed in a ceramic package 93. The ceramic package 93 is disposed on one surface of a wiring substrate 98 fixed to a support member 91. The ceramic package 93 includes a bottom wall 94 and a side wall 95. The side wall 95 is located on one side of the bottom wall 94 and defines an opening facing the bottom wall 94 in direction A. The bottom wall 94 is formed, for example, in the shape of a rectangular plate. The side wall 95 is formed, for example, in the shape of a rectangular frame. The wiring substrate 92 is fixed to the bottom wall 94 of the ceramic package 93 while being surrounded by the side wall 95 of the ceramic package 93.

[0023] The ceramic package 93 is provided with a plurality of lead pins 96. Each lead pin 96 extends from the bottom wall 94 to the other side. The plurality of lead pins 96 are terminal portions of a plurality of wires provided in the ceramic package 93, and are electrically connected to a plurality of wires on the wiring board 98. The image sensor 2 is electrically connected to external wiring via the plurality of wires on the wiring board 92, the plurality of wires (including the plurality of lead pins 96 which are terminal portions) provided in the ceramic package 93, and the plurality of wires on the wiring board 98. This enables input and output of signals to and from the image sensor 2.

[0024] The image sensor 2 has a light receiving area 2a. The light receiving area 2a includes a plurality of pixels arranged two-dimensionally along a plane perpendicular to direction A. The image sensor 2 is formed, for example, in the shape of a rectangular plate. The shape of the light receiving area 2a when viewed from direction A is, for example, rectangular. The image sensor 2 is, for example, a back-illuminated CMOS image sensor. The image sensor 2 may be, for example, a front-illuminated CMOS image sensor. The image sensor 2 may be another image sensor (for example, a back-illuminated CCD image sensor, a front-illuminated CCD image sensor, etc.). The image sensor 2 may be an area sensor or a line sensor.

[0025] A Peltier element 97 is disposed between the support member 91 and the wiring board 92, penetrating the bottom wall 94 and the wiring board 98. A heat absorbing portion of the Peltier element 97 is connected to the wiring board 92. A heat generating portion of the Peltier element 97 is connected to the support member 91. When the transmission electron microscope 10 is in operation, heat generated in the image sensor 2 is released to the support member 91 via the Peltier element 97, and the temperature of the image sensor 2 is maintained within a constant range.

[0026] The wall portion 111 includes an inward-facing flange portion 112. The flange portion 112 extends along the inner surface of the opening 111a. A groove 112a is formed in the flange portion 112. The groove 112a opens to the other side and extends along the flange portion 112. The flange portion 112 is formed, for example, in the shape of a rectangular frame. The groove 112a extends in a rectangular shape when viewed, for example, from direction A. The groove 112a faces a surface 95a on one side of the side wall 95 in direction A. An O-ring 113 is disposed between the surface 95a of the side wall 95 and the bottom surface of the groove 112a.

[0027] In the transmission electron microscope 10, when the support member 91 is attached to the wall portion 111, for example, by bolts, the side wall 95 of the ceramic package 93 fixed to the support member 91 approaches the flange portion 112. At this time, the O-ring 113 is crushed between the surface 95a of the side wall 95 and the bottom surface of the groove 112a, thereby ensuring airtightness of the space within the housing 11 and enabling the space within the housing 11 to be evacuated.

[0028] The first FOP 4 is disposed on the image sensor 2. The first FOP 4 is composed of a bundle of multiple optical fibers. The first FOP 4 has a light input surface 4a and a light output surface 4b. The light input surface 4a is the surface on one side of the first FOP 4 and is composed of multiple light input end faces of multiple optical fibers. The light output surface 4b is the surface on the other side of the first FOP 4 and is composed of multiple light output end faces of multiple optical fibers. The light output surface 4b faces the light receiving area 2a of the image sensor 2 in direction A. The first FOP 4 is formed, for example, in the shape of a quadrangular prism or a cylinder with a center line parallel to direction A.

[0029] The second FOP 6 is disposed on the first FOP 4. The second FOP 6 is composed of a bundle of multiple optical fibers. The second FOP 6 has a light input surface 6a and a light output surface 6b. The light input surface 6a is the surface on one side of the second FOP 6 and is composed of multiple light input end faces of multiple optical fibers. The light output surface 6b is the surface on the other side of the second FOP 6 and is composed of multiple light output end faces of multiple optical fibers. The light output surface 6b faces the light input surface 4a of the first FOP 4 in direction A. The second FOP 6 is formed, for example, in a cylindrical shape with a centerline parallel to direction A.

[0030] The thickness of the second FOP 6 (i.e., the distance between the light input surface 6a and the light output surface 6b) is greater than the thickness of the first FOP 4 (i.e., the distance between the light input surface 4a and the light output surface 4b). The thickness of the first FOP 4 is, for example, about 10 mm. The thickness of the second FOP 6 is, for example, about 20 mm. When viewed from direction A, the outer edge of the first FOP 4 is located outside the outer edge of the light receiving area 2a and inside the outer edge of the image sensor 2. When viewed from direction A, the outer edge of the second FOP 6 is located outside the outer edges of the first FOP 4, the image sensor 2, and the wiring board 92.

[0031] The adhesive layer 3 is disposed between the image sensor 2 and the light output surface 4b of the first FOP 4. In other words, the adhesive layer 3 is disposed between the image sensor 2 and the first FOP 4. The adhesive layer 3 is optically transparent. The first FOP 4 is adhered to the image sensor 2 by the adhesive layer 3. The thickness of the adhesive layer 3 is, for example, about 10 μm. The material of the adhesive layer 3 is, for example, an optically transparent epoxy resin.

[0032] The immersion oil layer 5 is disposed between the light input surface 4a of the first FOP 4 and the light output surface 6b of the second FOP 6. In other words, the immersion oil layer 5 is disposed between the first FOP 4 and the second FOP 6. The immersion oil layer 5 is in contact with the light output surface 6b and the light input surface 4a. The immersion oil layer 5 is filled between the light output surface 6b and the light input surface 4a. The thickness of the immersion oil layer is 3 μm or less.

[0033] The immersion oil layer 5 is a layer formed of oil (liquid) that is transparent to light emitted from the scintillator layer 8 in response to the incidence of the electron beam EB and has a refractive index of 1.4 to 1.9. Examples of oil that can be used to form the immersion oil layer 5 include "Immersion Oil F30cc (MXA22168)" manufactured by Nikon Solutions Corporation and "MOIL-30" manufactured by Evident Co., Ltd.

[0034] The transparent conductive film 7 is disposed between the light input surface 6a of the second FOP 6 and the scintillator layer 8. That is, the transparent conductive film 7 is disposed between the second FOP 6 and the scintillator layer 8. The transparent conductive film 7 is a film formed on the light input surface 6a by, for example, a vapor deposition method. The thickness of the transparent conductive film 7 is, for example, about 20 nm. The material of the transparent conductive film 7 is, for example, ITO. The shape of the transparent conductive film 7 when viewed from direction A is, for example, circular. When viewed from direction A, the outer edge of the transparent conductive film 7 coincides with the outer edge of the light input surface 6a.

[0035] The scintillator layer 8 is disposed on the transparent conductive film 7. That is, the scintillator layer 8 is disposed on the second FOP 6 via the transparent conductive film 7. The scintillator layer 8 and the transparent conductive film 7 are in contact with each other. The scintillator layer 8 is a layer whose thickness direction is in the direction A and contains GOS:Pr. The scintillator layer 8 is a layer formed on the transparent conductive film 7 by, for example, a precipitation method. The thickness of the scintillator layer 8 is, for example, about 10 μm. When viewed from the direction A, the shape of the scintillator layer 8 is, for example, circular. When viewed from the direction A, the outer edge of the scintillator layer 8 is located inside the outer edge of the transparent conductive film 7. In other words, when viewed from the direction A, the outer edge of the transparent conductive film 7 is located outside the outer edge of the scintillator layer 8.

[0036] The unitized second FOP 6, transparent conductive film 7, and scintillator layer 8 are held down by a holding member 114 relative to the unitized image sensor 2, adhesive layer 3, and first FOP 4. The holding member 114 includes a cylindrical main body 115, an inward flange 116, and an outward flange 117. The main body 115 is formed, for example, in the shape of a cylinder with a center line parallel to direction A. The holding member 114 is formed, for example, from metal. An inner side surface 115a of the main body 115 contacts the outer edge of the transparent conductive film 7 and the side surface of the second FOP 6. A surface 116a on the other side of the flange 116 contacts a surface 7a on one side of the transparent conductive film 7.

[0037] A plurality of spacers 118 are disposed between the wall portion 111 and the flange portion 117 of the holding member 114. The flange portion 117 of the holding member 114 is fixed to the wall portion 111 via the plurality of spacers 118, for example, with bolts or the like, thereby holding down the unitized second FOP 6, transparent conductive film 7, and scintillator layer 8 relative to the unitized image sensor 2, adhesive layer 3, and first FOP 4. In the electron beam detection device 1, the transparent conductive film 7 is electrically connected to the wall portion 111 via the holding member 114 and the plurality of spacers 118, and the transparent conductive film 7 is grounded. For example, a single cylindrical spacer 118 may be disposed between the wall portion 111 and the flange portion 117 of the holding member 114.

[0038] As described above, in the electron beam detection device 1, the immersion oil layer 5 is disposed between the first FOP 4 on the image sensor 2 side and the second FOP 6 on the scintillator layer 8 side. This allows, for example, if the scintillator layer 8 or the second FOP 6 deteriorates, to leave the image sensor 2 together with the first FOP 4, and to replace the scintillator layer 8 and the second FOP 6 with new ones. Furthermore, in the electron beam detection device 1, the immersion oil layer 5 contacts the light output surface 6 b of the second FOP 6 and the light input surface 4 a of the first FOP 4. This allows, for example, when the space within the housing 11 is evacuated, the fluidity of the immersion oil layer 5 to bring the light output surface 6 b of the second FOP 6 and the light input surface 4 a of the first FOP 4 into optically tight contact via the immersion oil layer 5, thereby enabling an image to be transmitted accurately from the light output surface 6 b of the second FOP 6 to the light input surface 4 a of the first FOP 4. Therefore, according to the electron beam detection device 1, it is possible to replace the scintillator layer 8 with a new one while leaving the image sensor 2 in place, and it is possible to suppress a decrease in resolution in the detection results of the electron beam EB (in the case of the transmission electron microscope 10, an electron beam transmission image of the sample S).

[0039] In the electron beam detection device 1, the thickness of the immersion oil layer 5 is 3 μm or less, which allows the image to be transmitted from the light output surface 6 b of the second FOP 6 to the light input surface 4 a of the first FOP 4 with higher accuracy.

[0040] In the electron beam detection device 1, the thickness of the second FOP 6 is greater than the thickness of the first FOP 4. As a result, the electron beam EB reaching the immersion oil layer 5 is more likely to be attenuated by the second FOP 6 than when the thickness of the second FOP 6 is smaller than the thickness of the first FOP 4, and deterioration of the image sensor 2 and the first FOP 4 due to irradiation with the electron beam EB can be suppressed.

[0041] In the electron beam detection device 1, when viewed from direction A, the outer edge of the second FOP 6 is located outside the outer edge of the first FOP 4. This makes it possible to expose areas (e.g., circuit areas) other than the light receiving area 2a of the image sensor 2 by reducing the size of the first FOP 4 when viewed from direction A, while suppressing deterioration of those areas (e.g., circuit areas) due to irradiation with the electron beam EB by increasing the size of the second FOP 6 when viewed from direction A.

[0042] In the electron beam detection device 1, an optically transparent adhesive layer 3 is disposed between the image sensor 2 and the first FOP 4, and the first FOP 4 is adhered to the image sensor 2 by the adhesive layer 3. This makes it possible to suppress misalignment of the first FOP 4 with respect to the image sensor 2.

[0043] In the electron beam detection device 1, the scintillator layer 8 is a layer containing GOS:Pr. This allows the scintillator layer 8, which is relatively susceptible to deterioration, to be replaced with a new one together with the second FOP 6.

[0044] In the electron beam detection device 1, the transparent conductive film 7 is disposed between the second FOP 6 and the scintillator layer 8. This makes it possible to prevent charging breakdown of the scintillator layer 8 by grounding the transparent conductive film 7. Furthermore, since the light emitted from the scintillator layer 8 in response to the incidence of the electron beam EB is prevented from being reflected by the transparent conductive film 7, it is possible to prevent a decrease in resolution in the detection results of the electron beam EB.

[0045] In the electron beam detection device 1, when viewed from direction A, the outer edge of the transparent conductive film 7 is located outside the outer edge of the scintillator layer 8. This makes it easier to bring the holding member 114 into contact with the outer edge region of the transparent conductive film 7, so that the transparent conductive film 7 can be easily and reliably grounded.

[0046] The transmission electron microscope 10 includes an electron beam detection device 1, an electron beam source 12, and a sample support part 14 arranged between the electron beam source 12 and the electron beam detection device 1. As described above, the transmission electron microscope 10 makes it possible to replace the scintillator layer 8 with a new one in the electron beam detection device 1 while leaving the image sensor 2, and also makes it possible to suppress a decrease in resolution in the detection results of the electron beam EB.

[0047] FIG. 3 is a diagram showing the light utilization efficiency of the comparative example and example 1. In the comparative example, a configuration was prepared in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 were in contact with each other in the air. In this configuration, light was input to the light input surface 6a of the second FOP 6, and the light output from the light output surface 4b of the first FOP 4 was detected by the image sensor 2. In example 1, a configuration was prepared in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 were in optically close contact with each other via an immersion oil layer 5 having a thickness of 2 to 3 μm. In this configuration, light with the same intensity as in the comparative example was input to the light input surface 6a of the second FOP 6, and the light output from the light output surface 4b of the first FOP 4 was detected by the image sensor 2. FIG. 3 shows the average, minimum, maximum, and median light count values ​​detected by the image sensor 2 for each of the comparative example and example 1. 3, the count value of Example 1 is improved by about 20% compared to the count value of the Comparative Example. From this, it can be said that the "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are optically in close contact with each other via the immersion oil layer 5" is a configuration in which the light utilization efficiency is improved compared to the "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are in contact with each other in the air."

[0048] 4 shows the MTFs for Examples 2 and 3 and the reference example. In Example 2, a "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are optically in close contact with each other via an immersion oil layer 5 having a thickness of 20 μm" was prepared, and the MTF was measured for the detection results of the image sensor 2 acquired under specified conditions in that configuration. In Example 3, a "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are optically in close contact with each other via an immersion oil layer 5 having a thickness of 3 μm or less" was prepared, and the MTF was measured for the detection results of the image sensor 2 acquired under the same conditions as in Example 2. In the reference example, a "configuration including an FOP having a shape in which the second FOP 6 and the first FOP 4 are integrated" was prepared, and the MTF was measured for the detection results of the image sensor 2 acquired under the same conditions as in Example 2 in that configuration. 4, a sufficient MTF was obtained in Example 2, and an MTF closer to that of the reference example was obtained in Example 3. From this, it can be said that the "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are in optically close contact with each other via an immersion oil layer 5 having a thickness of 3 μm or less" is effective in obtaining high resolution in the detection results of the electron beam EB.

[0049] 5 shows the MTFs for Examples 4 and 5 and the reference example. In Example 4, a configuration was prepared in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 were optically in close contact with each other via a 3 μm-thick immersion oil layer 5, and the scintillator layer 8 disposed directly on the second FOP 6 was covered with an aluminum film. The MTF was measured for the detection results of the image sensor 2 acquired under specified conditions in this configuration. The aluminum film serves to prevent electrostatic breakdown of the scintillator layer 8 by grounding the aluminum film. In Example 5, a configuration was prepared in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 were optically in close contact with each other via a 3 μm-thick immersion oil layer 5, and the scintillator layer 8 was disposed on the second FOP 6 via a transparent conductive film 7. The MTF was measured for the detection results of the image sensor 2 acquired under the same conditions as in Example 4. In the reference example, a "configuration including an FOP having an integrated shape in which the second FOP 6 and the first FOP 4 are integrated, and in which the scintillator layer 8 disposed directly on the light input surface of the FOP is covered with an aluminum film" was prepared, and the MTF of the detection results of the image sensor 2 obtained in this configuration under the same conditions as in Example 4 was measured. The results shown in Figure 5 show that a sufficient MTF was obtained in Example 4, and an MTF exceeding that of the reference example was obtained in Example 5. From this, it can be said that the "configuration in which the light output surface 6b of the second FOP 6 and the light input surface 4a of the first FOP 4 are optically in close contact with each other via a 3 μm-thick immersion oil layer 5, and the scintillator layer 8 is disposed on the second FOP 6 via a transparent conductive film 7" is effective in obtaining high resolution in the detection results of the electron beam EB.

[0050] 5, it is expected that a "configuration including an FOP having a shape in which the second FOP 6 and the first FOP 4 are integrated, and in which the scintillator layer 8 is disposed on the second FOP 6 via the transparent conductive film 7" is even more effective in obtaining high resolution in the detection results of the electron beam EB. In other words, with an "electron beam detection device including an image sensor, at least one fiber optic plate disposed on the image sensor, a scintillator layer disposed on the at least one fiber optic plate, and a transparent conductive film disposed between the at least one fiber optic plate and the scintillator layer," charging breakdown of the scintillator layer can be suppressed by grounding the transparent conductive film, and a decrease in resolution in the detection results of the electron beam can be suppressed.

[0051] The present disclosure is not limited to the above example. For example, the thickness of the immersion oil layer 5 may be greater than 3 μm. The immersion oil layer 5 may also contain multiple optical particles (e.g., beads) having the same diameter. In this case, the distance between the light input surface 4 a of the first FOP 4 and the light output surface 6 b of the second FOP 6 can be maintained constant. Furthermore, the distance between the light input surface 4 a of the first FOP 4 and the light output surface 6 b of the second FOP 6 can be adjusted by adjusting the diameter of the optical particles.

[0052] The scintillator layer 8 may be disposed directly (i.e., without the transparent conductive film 7) on the second FOP 6. The scintillator layer 8 may also be a layer containing another scintillator material (e.g., P43, P46, YAP:Ce, LuAG:Pr, BFCl:Eu, etc.).

[0053] The thickness of the second FOP 6 may be smaller than or the same as the thickness of the first FOP 4. When viewed from direction A, the outer edge of the second FOP 6 may be located inside the outer edge of the first FOP 4, or may be coincident with the outer edge of the first FOP 4. An immersion oil layer may be disposed between the image sensor 2 and the first FOP 4 instead of the adhesive layer 3.

[0054] 1...electron beam detection device, 2...image sensor, 3...adhesive layer, 4...first FOP (first fiber optic plate), 4a...light input surface, 5...immersion oil layer, 6...second FOP (second fiber optic plate), 6b...light output surface, 7...transparent conductive film, 8...scintillator layer, 10...transmission electron microscope, 12...electron beam source, 14...sample support portion, A...direction.

Claims

1. An electron beam detection device comprising: an image sensor; a first fiber optic plate disposed on the image sensor; a second fiber optic plate disposed on the first fiber optic plate; a scintillator layer disposed on the second fiber optic plate; and an immersion oil layer disposed between the first fiber optic plate and the second fiber optic plate, wherein the immersion oil layer is in contact with the light output surface of the second fiber optic plate and the light input surface of the first fiber optic plate.

2. The electron beam detection device according to claim 1, wherein the thickness of the immersion oil layer is 3 μm or less.

3. An electron beam detection device according to claim 1 or 2, wherein the thickness of said second fiber optic plate is greater than the thickness of said first fiber optic plate.

4. An electron beam detection device described in any one of claims 1 to 3, wherein when viewed in the thickness direction of the scintillator layer, the outer edge of the second fiber optic plate is located outside the outer edge of the first fiber optic plate.

5. An electron beam detection device according to any one of claims 1 to 4, further comprising an optically transparent adhesive layer disposed between said image sensor and said first fiber optic plate, said first fiber optic plate being adhered to said image sensor by said adhesive layer.

6. An electron beam detection device according to any one of claims 1 to 5, wherein the scintillator layer is a layer containing GOS:Pr.

7. An electron beam detection device according to any one of claims 1 to 6, further comprising a transparent conductive film disposed between said second fiber optic plate and said scintillator layer.

8. The electron beam detection device according to claim 7, wherein the outer edge of the transparent conductive film is located outside the outer edge of the scintillator layer when viewed in the thickness direction of the scintillator layer.

9. A transmission electron microscope comprising: an electron beam detection device according to any one of claims 1 to 8; an electron beam source; and a sample support portion disposed between the electron beam source and the electron beam detection device.

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