Detection device

Abstract

To provide a detection device capable of suppressing a dark current due to electrification of an insulation part from increasing even when incident charged particles increase.SOLUTION: A detection device 1 includes: an insulation layer 15 and a passivation layer 21 (insulation part) which cover a pn junction region K such that a p type semiconductor layer 14 is exposed in part as an incidence region R for electron E, and electrically insulate a p electrode layer 16 and an n electrode layer 17; and a scattered electron shield part 18 which has an opening part 18a for exposing the incidence region R, and is so arranged on the side of one surface 13a that the insulation part is not exposed from the opening part 18a, wherein a reflected electron shield part 19 partitioning off the incidence region R and the insulation part extends at an edge part Ra of the incidence region R along the edge part Ra.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a detection device for detecting charged particles.

Background Art

[0002] As a conventional detection device, for example, there is one described in Non-Patent Document 1. This conventional detection device includes a p-type impurity region serving as an incident region for charged particles on one surface of an n-type semiconductor substrate. A pn junction region is formed between the semiconductor substrate and the p-type impurity region. The pn junction region is exposed on the surface of the semiconductor substrate and is covered with an insulating portion except for the incident region of charged particles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the detection device as described above, there has been a problem that the dark current increases due to the generation of crystal defects when charged particles enter the pn junction region. In response to such a problem, it is conceivable to provide a shielding plate that restricts the path of charged particles entering the pn junction region. For example, in the electron detection device described in Patent Document 1, a shielding member having an opening for allowing charged particles to enter the p-type impurity region is provided so as to cover the exposed surface of the pn junction region.

[0006] Incidentally, even in a configuration in which a shielding member is disposed in the detection device, when the charged particles incident on the incident region increase, it is conceivable that the electrons reflected on the member surface near the incident region (hereinafter referred to as "reflected electrons") increase. When the reflected electrons increase and the electrons reaching the insulating portion that electrically insulates the p electrode electrically connected to the p-type semiconductor layer and the n electrode electrically connected to the n-type semiconductor layer increase, the insulating portion may be charged, which may contribute to an increase in the dark current.

[0007] The present disclosure has been made to solve the above problems, and an object thereof is to provide a detection device capable of suppressing an increase in dark current caused by charging of an insulating portion even when the incident charged particles increase.

Means for Solving the Problems

[0008] The gist of the present disclosure is as follows.

[0009] [1] A first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type provided so as to be exposed on one surface of the first semiconductor layer and forming a pn junction region with the first semiconductor layer, a first electrode layer electrically connected to the first semiconductor layer, a second electrode layer electrically connected to the second semiconductor layer, an insulating portion covering the pn junction region so that a part of the second semiconductor layer is exposed as an incident region of charged particles and electrically insulating the first electrode layer and the second electrode layer, and an opening for exposing the incident region, and a first shielding portion disposed on the one surface side so that the insulating portion is not exposed from the opening in a plan view of the one surface, and a second shielding portion that partitions the incident region and the insulating portion in the plan view of the one surface extends along the edge at the edge of the incident region. A detection device.

[0010] In this detection device, a first shielding portion is arranged so that the insulating portion is not visible to charged particles heading toward the incident region. Therefore, even when charged particles heading toward the incident region pass through the opening at various angles due to scattering, it is possible to suppress the charged particles from directly reaching the insulating portion. Further, in this detection device, a second shielding portion that partitions the incident region and the insulating portion extends along the edge of the incident region. By extending the second shielding portion along the edge of the incident region, it is possible to suppress reflected electrons reflected from the surface of a member near the incident region from reaching the insulating portion. Therefore, in this detection device, even when the number of charged particles incident on the incident region increases, it is possible to suppress the charging of the insulating portion, and an increase in dark current due to the charging of the insulating portion can be suppressed.

[0011] [2] The detection device according to [1], wherein the second shielding portion extends over the entire edge of the incident region. In this case, by extending the second shielding portion over the entire edge of the incident region, it is possible to more effectively suppress reflected electrons reflected from the surface of a member near the incident region from reaching the insulating portion. Therefore, an increase in dark current due to the charging of the insulating portion can be more reliably suppressed.

[0012] [3] The detection device according to [1] or [2], wherein the first shielding portion has a first conductive layer corresponding to the second semiconductor layer, the second shielding portion is made of a conductive material, and the second semiconductor layer and the first conductive layer are electrically connected. In this case, it is possible to simply extract a signal from the detection device via the first conductive layer. Further, since the second semiconductor layer and the first conductive layer have the same potential and the charging of the first shielding portion is suppressed, the output signal can be stabilized.

[0013] [4] The detection device according to any one of [1] to [3], wherein the second shielding portion is composed of a first portion on the second semiconductor layer side and a second portion on the second shielding portion side. In this case, the second shielding portion can be formed simply and accurately by separately forming the first portion and the second portion while aligning their positions and opposing them.

[0014] [5] The detection device according to [4], wherein the second shielding portion is configured in multiple layers, and in the multiple second shielding portions, the thickness of the first portion and the thickness of the second portion are different from each other. In this case, by making the second shielding portion multiple layers, it is possible to effectively suppress the reflected electrons from reaching the insulating portion. Further, since the thickness of the first portion and the thickness of the second portion are different from each other in the multiple second shielding portions, even if there is a gap between the first portion and the second portion, it is possible to suppress the reflected electrons from reaching the insulating portion. If there is a gap between the first portion and the second portion, when the detection device is used in a vacuum environment, it is possible to preferably suppress the residual gas in the vicinity of the second shielding portion.

[0015] [6] The detection device according to any one of [1] to [5], wherein the second shielding portion is configured in multiple layers with at least a part having a discontinuous portion, and the multiple second shielding portions are arranged such that the discontinuous portions do not face each other. In this case, by making the second shielding portion multiple layers, even if a discontinuous portion is provided in each of the multiple second shielding portions, it is possible to effectively suppress the reflected electrons from reaching the insulating portion. Further, by not making the discontinuous portions in the multiple second shielding portions face each other, when the detection device is used in a vacuum environment, it is possible to preferably suppress the residual gas in the vicinity of the second shielding portion.

[0016] [7] The detection device according to any one of [1] to [3], wherein the second shielding portion is formed by the edge of the opening of the first shielding portion protruding to the one surface side. In this case, the second shielding portion can be configured with a simple structure.

[0017] [8] The detection device according to any one of [1] to [7], wherein in a plan view of the one surface, a third shielding portion is provided in a region outside the second shielding portion to partition the insulating portion between the second shielding portion and the region outside it. In this case, it is possible to suppress the intrusion of charged particles from the region outside the second shielding portion by the third shielding portion. Therefore, it is possible to more reliably suppress the increase in dark current caused by the charging of the insulating portion.

[0018] [9] The first shielding portion has a second conductive layer corresponding to the first semiconductor layer, and the third shielding portion is made of a conductive material and electrically connects the first semiconductor layer and the second conductive layer. The detection device according to [8]. In this case, the signal can be easily extracted from the detection device via the second conductive layer. Further, since the first semiconductor layer and the second conductive layer have the same potential and the charging of the first shielding portion is suppressed, the output signal can be stabilized.

[0019]

[10] The first shielding portion is made of ceramic. The detection device according to any one of [1] to [9]. In this case, the withstand voltage of the first shielding portion can be sufficiently ensured. By ensuring the withstand voltage of the first shielding portion, it becomes possible to narrow the distance between the first shielding portion and one surface of the first semiconductor layer and the second semiconductor layer, and it is possible to more effectively suppress the reflected electrons from reaching the insulating portion.

[0020]

[11] The first shielding portion is made of Si. The detection device according to any one of [1] to [9]. In this case, the first shielding portion can be manufactured at low cost.

[0021]

[12] The second shielding portion is made of Au. The detection device according to any one of [1] to

[11] . In this case, the degree of freedom of the formation pattern of the second shielding portion can be easily ensured, and sufficient bonding strength can be obtained even in a small metallized region.

Effect of the Invention

[0022] According to the present disclosure, even when the incident charged particles increase, an increase in dark current due to the charging of the insulating portion can be suppressed.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0024] Hereinafter, with reference to the drawings, a preferred embodiment of a detection device according to one aspect of the present disclosure will be described in detail.

[0025] FIG. 1 is a schematic cross-sectional view showing the configuration of a detection device according to an embodiment of the present disclosure. The detection device 1 is a device for detecting charged particles such as ions and electrons, and in the example of FIG. 1, it is configured as a phototube. The detection device 1 has a cylindrical valve 2. The inside of the valve 2 is in a vacuum state. The opening at one end side of the valve 2 is sealed by a photoelectric panel 3 serving as an electron source. On the inner surface of the valve 2 in the photoelectric panel 3, a photoelectric surface 4 that emits electrons (photoelectrons) E in response to the incidence of photons C is provided. The opening at the other end side of the valve 2 is sealed by a stem 5. A plurality of through holes are provided in the stem 5. Lead pins are inserted into each of the through holes and fixed by a joining member such as glass.

[0026] Inside the valve 2, a plurality of grids (not shown) for narrowing down the electrons E emitted from the photoelectric surface 4 are provided. Also, inside the valve 2, a detection unit 11 is provided between the grid and the stem 5. The detection unit 11 is an electron multiplication type semiconductor electron sensor and outputs a signal V in response to the incidence of electrons E. In the present embodiment, the detection unit 11 has a structure equivalent to an avalanche photodiode.

[0027] The photocathode 4 is supplied with a constant voltage from the power supply 6. Further, the detection unit 11 is supplied with a reverse bias voltage from the power supply 7. When photons C are incident on the photocathode 4 in this state, electrons E are emitted from the photocathode 4 into the valve 2. The emitted electrons E pass through the grid and then enter the incident region R in the detection unit 11. Due to the collision at the time of incidence of the electrons E, in the detection unit 11, electron-hole pairs corresponding to the energy lost by the electrons E due to the collision are generated. The generated electron-hole pairs drift in the detection unit 11 to which the reverse bias voltage is supplied, and in the pn junction region K (see FIG. 2), they are avalanche multiplied at a multiplication factor corresponding to the reverse bias voltage.

[0028] FIG. 2 is a schematic cross-sectional view showing the configuration of the detection unit. Further, FIG. 3 is a schematic plan view thereof. However, in FIG. 3, for convenience of explanation, the configuration of the detection unit 11 in a plan view is shown in a state where the scattering electron shielding portion 18 described later is removed. As shown in FIGS. 2 and 3, the detection unit 11 includes a substrate 12, an n-type semiconductor layer (first semiconductor layer) 13, a p-type semiconductor layer (second semiconductor layer) 14, an insulating layer 15, a p-electrode layer (second electrode layer) 16, an n-electrode layer (first electrode layer) 17, a scattering electron shielding portion (first shielding portion) 18, a reflected electron shielding portion (second shielding portion) 19, and a recirculating electron shielding portion (third shielding portion) 20.

[0029] The substrate 12 is a part that serves as the base of the detection unit 11. The substrate 12 is formed in a rectangular shape in a plan view by a metal such as Au, for example. The n-type semiconductor layer 13 is a semiconductor layer having an n-type (first conductivity type) conductivity type. The n-type semiconductor layer 13 is made of, for example, Si (silicon) and is formed on the entire surface of one surface 12a of the substrate 12. The p-type semiconductor layer 14 is a semiconductor layer having a p-type (second conductivity type) conductivity type. The p-type semiconductor layer 14 is made of, for example, Si (silicon) and is provided so as to be partially exposed on one surface 13a of the n-type semiconductor layer 13.

[0030] In this embodiment, the p-type semiconductor layer 14 is in a state of being buried in the central portion of one surface 13a of the n-type semiconductor layer 13 such that the exposed portion from one surface 13a of the n-type semiconductor layer 13 is circular in plan view and is flush with one surface 13a of the n-type semiconductor layer 13. A pn junction region K is formed between the p-type semiconductor layer 14 and the n-type semiconductor layer 13.

[0031] The insulating layer 15 is a portion that electrically insulates the p-electrode layer 16 and the n-electrode layer 17. The insulating layer 15 is made of a material having electrical insulation properties such as, for example, SiO2. The insulating layer 15 covers the pn junction region K such that a part of the p-type semiconductor layer 14 is exposed as the incident region R of electrons E. Here, the insulating layer 15 is provided so as to cover the peripheral portion of the exposed portion of the p-type semiconductor layer 14 and substantially the entire one surface 13a of the n-type semiconductor layer 13 on one surface 13a of the n-type semiconductor layer 13. The central circular region of the p-type semiconductor layer 14 is exposed from the central opening 15a of the insulating layer 15 and serves as the incident region R where electrons E are incident.

[0032] The p-electrode layer 16 is an electrode portion electrically connected to the p-type semiconductor layer 14. The n-electrode layer 17 is an electrode portion electrically connected to the n-type semiconductor layer 13. The p-electrode layer 16 and the n-electrode layer 17 are Al films formed by vapor deposition of, for example, Al (aluminum). When forming the p-electrode layer 16, a contact hole 15b for exposing the p-type semiconductor layer 14 is provided in the insulating layer 15. The p-electrode layer 16 is formed in a predetermined pattern on the insulating layer 15 in a state of filling the contact hole 15b. The n-electrode layer 17 is formed in a predetermined pattern on the insulating layer 15 outside the p-electrode layer 16 in a state of being spaced apart from the p-electrode layer 16 along the outer surface 15c of the insulating layer 15.

[0033] The above-described insulating layer 15, p-electrode layer 16, and n-electrode layer 17 are covered by a passivation layer 21. The passivation layer 21 is a layer provided for the purpose of surface protection of the p-electrode layer 16 and the n-electrode layer 17. The passivation layer 21 is formed of an insulating material such as SiN (silicon nitride) or SiO2 (silicon oxide), for example. The passivation layer 21 is provided with an opening 21A that exposes the incident region R together with the opening 15a of the insulating layer 15, an opening 21B that exposes the p-electrode layer 16 corresponding to the reflected electron shielding portion 19, and an opening 21C that exposes the n-electrode layer 17 corresponding to the backscattered electron shielding portion 20. In the present embodiment, the passivation layer 21, together with the insulating layer 15, constitutes an "insulating portion that covers the pn junction region so that a part of the p-type semiconductor layer 14 is exposed as the incident region R of charged particles and electrically insulates the p-electrode layer 16 and the n-electrode layer 17" in the present disclosure. In the case where the passivation layer 21 is omitted, the insulating layer 15 alone constitutes the insulating portion of the present disclosure.

[0034] The scattered electron shielding portion 18 is a member that restricts the path of electrons E traveling from the photocathode 4 toward the incident region R. The scattered electron shielding portion 18 is formed in a disk shape with a thickness sufficient to shield electrons E by an insulating material such as ceramic, for example. In the present embodiment, the diameter of the scattered electron shielding portion 18 is slightly smaller than the planar dimensions of the substrate 12 and the n-type semiconductor layer 13, but the region outside the opening 21C of the passivation layer 21 is covered with the scattered electron shielding portion 18.

[0035] An opening 18a having a circular cross-section with a diameter corresponding to the diameter of the incident region R is provided at the center of the scattered electron shielding portion 18. The scattered electron shielding portion 18 is disposed close to one surface 13a of the n-type semiconductor layer 13 such that the opening 18a faces the incident region R. As a result, in a plan view of the one surface 13a, the insulating layer 15 and the passivation layer 21, which are insulating portions, are not exposed (not visible) from the opening 18a of the scattered electron shielding portion 18.

[0036] Among the electrons E emitted from the photocathode 4, some pass through the opening 18a along the axial direction (the normal direction of the incident region R), while others may scatter off the inner wall of the valve 2 or the like and pass through the opening 18a at various angles. However, by disposing the scattered electron shielding portion 18 having a certain thickness in proximity to one surface 13a of the n-type semiconductor layer 13, the scattered electrons Ea incident obliquely with respect to the opening 18a collide with the inner wall surface of the opening 18a of the scattered electron shielding portion 18 or the like, and their progress is blocked.

[0037] On the surface of the scattered electron shielding portion 18, a p-conductive layer (first conductive layer) 22 corresponding to the p-type semiconductor layer 14 and an n-conductive layer (second conductive layer) 23 corresponding to the n-type semiconductor layer 13 are provided. The p-conductive layer 22 and the n-conductive layer 23 are, for example, Au films formed by vapor deposition of Au (gold). The p-conductive layer 22 is formed over the peripheral edge of the opening 18a, the inner wall surface of the opening 18a, and the other surface 18c of the scattered electron shielding portion 18 (the surface facing the one surface 13a of the n-type semiconductor layer 13) on one surface 18b of the scattered electron shielding portion 18. The n-conductive layer 23 is formed on one surface 18b of the scattered electron shielding portion 18, outside the p-conductive layer 22 and spaced apart from the p-conductive layer 22.

[0038] Conductive wires (not shown) or the like are electrically connected to each of the p-conductive layer 22 and the n-conductive layer 23, and a predetermined voltage is applied through the wires. In this embodiment, the p-conductive layer 22, the reflected electron shielding portion 19, the p-electrode layer 16, and the p-type semiconductor layer 14 electrically connected thereto are at the ground potential. Also, a positive voltage of, for example, about 400 V to 500 V is applied to the n-conductive layer 23, the return electron shielding portion 20, the n-electrode layer 17, and the n-type semiconductor layer 13 electrically connected thereto. By defining the voltages of the p-conductive layer 22 and the n-conductive layer 23, a floating state can be avoided, and the operation of the detection device 1 can be stabilized.

[0039] The reflected electron shielding portion 19 is a member that suppresses electrons E (hereinafter referred to as "reflected electrons Eb") reflected from the surface of the member near the incident region R from reaching the insulating portion. The reflected electron shielding portion 19 is, for example, an Au film formed by vapor deposition of Au (gold). The reflected electron shielding portion 19 extends along the edge Ra of the incident region R so as to partition the incident region R and the insulating portion in a plan view of one surface 13a. In the present embodiment, the reflected electron shielding portion 19 is provided in an annular shape that is continuous over the entire edge Ra of the incident region R (see FIG. 3).

[0040] Here, as shown in FIG. 2, the space from the opening 18a of the scattered electron shielding portion 18 to the incident region R is referred to as an incident space H. A part of the reflected electrons Eb emitted in the reflection direction due to electrons incident on the surface of the member facing the incident space H (such as the surface of the p-type semiconductor layer 14 and the inner wall of the opening 18a) can reach the insulating portion through various paths. When the electrons E incident on the incident region R increase, the reflected electrons Eb increase accordingly, and those that reach the insulating portion covering the pn junction region (particularly the portion where the p electrode layer 16 and the n electrode layer 17 are electrically insulated in the passivation layer 21) may occur. On the other hand, since the reflected electron shielding portion 19 extends along the edge Ra of the incident region R, the reflected electrons Eb emitted due to the incidence of the electrons E on the incident space H collide with the reflected electron shielding portion 19, and their progress is blocked.

[0041] In this embodiment, the reflected electron shielding portion 19 has a portion 19a extending along the inner wall surface of the opening 15a at the center of the insulating layer 15 and the inner wall surface of the opening 21A of the passivation layer 21, a portion 19b filling the opening 21B of the passivation layer 21, and a portion 19c extending on the passivation layer 21 so as to connect these portions 19a and 19b to each other (see Fig. 2). The portion 19a contacts the p-type semiconductor layer 14 within the opening 15a of the insulating layer 15, and the portion 19b contacts the p-electrode layer 16 within the opening 21B of the passivation layer 21. Further, the portion 19c contacts the p-conductive layer 22 of the scattered electron shielding portion 18 on the passivation layer 21. Thereby, the reflected electron shielding portion 19 is in a state of electrically connecting the p-type semiconductor layer 14 and the p-conductive layer 22 of the scattered electron shielding portion 18, and a predetermined potential is applied to the p-type semiconductor layer 14 via the p-conductive layer 22 and the reflected electron shielding portion 19.

[0042] The encroaching electron shielding portion 20 is a member that suppresses the encroachment of electrons E from a region outside the reflected electron shielding portion 19. The encroaching electron shielding portion 20 is, like the reflected electron shielding portion 19, for example, an Au film formed by vapor deposition of Au (gold). The encroaching electron shielding portion 20 is provided so as to partition an insulating portion (here, the portion located between the p-electrode layer 16 and the n-electrode layer 17 in the passivation layer 21) between it and the reflected electron shielding portion 19 from a region outside it.

[0043] More specifically, the encroaching electron shielding portion 20 extends linearly along each of the four sides of the detection portion 11 in a plan view of one surface 13a so that the reflected electron shielding portion 19 cannot be seen when viewed from the outside of the detection portion 11, and is longer than the diameter of the annular reflected electron shielding portion 19 (see Fig. 3). In this embodiment, the ends of the encroaching electron shielding portions 20 on each side are discontinuous. The encroaching electron shielding portion 20 is provided in a rectangular frame shape with discontinuous corners so as to surround the reflected electron shielding portion 19 when viewed as a whole.

[0044] Among the electrons E emitted from the photocathode 4, there may be those that are scattered or reflected by the inner wall of the valve 2 or the like and enter between the n-type semiconductor layer 13 and the scattered electron shielding portion 18 from the side of the detection device 1 without heading toward the opening 18a of the scattered electron shielding portion 18 (hereinafter referred to as "re-entering electrons Ec"). On the other hand, by arranging the re-entering electron shielding portion 20 so that the reflected electron shielding portion 19 cannot be seen from the outside of the detection portion 11, such re-entering electrons Ec collide with the re-entering electron shielding portion 20, and their progress is blocked.

[0045] In the present embodiment, the re-entering electron shielding portion 20 has a portion 20a that fills the opening 21C of the passivation layer 21 and a portion 20b that protrudes from the opening 21C. The portion 20a is in contact with the n-electrode layer 17 within the opening 21C of the passivation layer 21. Further, the portion 20b protrudes from the opening 21C of the passivation layer 21, extends toward the scattered electron shielding portion 18, and is in contact with the n-conductive layer 23 of the scattered electron shielding portion 18. Thereby, the re-entering electron shielding portion 20 is in a state of electrically connecting the n-type semiconductor layer 13 and the n-conductive layer 23 of the scattered electron shielding portion 18, and a predetermined potential is applied to the n-type semiconductor layer 13 via the n-conductive layer 23 and the re-entering electron shielding portion 20.

[0046] As described above, in the detection device 1, the scattered electron shielding portion 18 is arranged so that the insulating layer 15 and the passivation layer 21, which are insulating portions, cannot be seen through with respect to the electrons E heading toward the incident region R. Therefore, even when the electrons E heading toward the incident region R pass through the opening 18a at various angles due to scattering, it is possible to suppress the scattered electrons Ea from directly reaching the insulating portion. Further, in the detection device 1, the reflected electron shielding portion 19 that partitions the incident region R and the insulating portion extends along the edge Ra of the incident region R. By the reflected electron shielding portion 19 extending along the edge Ra of the incident region R, it is possible to suppress the reflected electrons Eb reflected from the surface of the member near the incident region R from reaching the insulating portion. Therefore, in the detection device 1, even when the number of electrons E incident on the incident region R increases, it is possible to suppress the charging of the insulating portion, and it is possible to suppress an increase in dark current caused by the charging of the insulating portion.

[0047] In this embodiment, the reflected electron shielding portion 19 extends over the entire edge Ra of the incident region R. By having the reflected electron shielding portion 19 extend over the entire edge Ra of the incident region R, it is possible to more effectively suppress the reflected electrons Eb reflected from the member surface in the vicinity of the incident region R from reaching the insulating portion. Therefore, an increase in dark current due to charging of the insulating portion can be more reliably suppressed.

[0048] In this embodiment, the scattered electron shielding portion 18 has a p-conductive layer 22 corresponding to the p-type semiconductor layer 14, and the reflected electron shielding portion 19 is made of a conductive material and electrically connects the p-type semiconductor layer 14 and the p-conductive layer 22. According to such a configuration, extraction of a signal from the detection device 1 and application of a potential to the p-type semiconductor layer 14 can be easily carried out via the p-conductive layer 22. Also, since the p-type semiconductor layer 14 and the p-conductive layer 22 have the same potential and charging of the scattered electron shielding portion 18 is suppressed, stabilization of the output signal can be achieved.

[0049] In this embodiment, in a plan view of one surface 13a, a converging electron shielding portion 20 that partitions the insulating portion between itself and the reflected electron shielding portion 19 from the region outside thereof is provided in a region outside the reflected electron shielding portion 19. By providing such a converging electron shielding portion 20, it is possible to suppress the intrusion of electrons from a region outside the reflected electron shielding portion 19. Therefore, an increase in dark current due to charging of the insulating portion can be more reliably suppressed.

[0050] In this embodiment, the scattered electron shielding portion 18 has an n-conductive layer 23 corresponding to the n-type semiconductor layer 13, and the converging electron shielding portion 20 is made of a conductive material and electrically connects the n-type semiconductor layer 13 and the n-conductive layer 23. According to such a configuration, extraction of a signal from the detection device 1 and application of a potential to the n-type semiconductor layer 13 can be easily carried out via the n-conductive layer 23. Also, since the n-type semiconductor layer and the n-conductive layer 23 have the same potential and charging of the scattered electron shielding portion 18 is suppressed, stabilization of the output signal can be achieved.

[0051] When the detection device 1 is a phototube having a photocathode 4 as in the present embodiment, the back-in electron shielding portion 20 also functions as a member that suppresses the adhesion of the alkali metal used in the formation process of the photocathode 4 to the insulating portion (particularly the portion located between the p-electrode layer 16 and the n-electrode layer 17 in the passivation layer 21). By suppressing the adhesion of the alkali metal to the insulating portion located between the p-electrode layer 16 and the n-electrode layer 17, a decrease in the surface resistance of the insulating portion can be prevented, and the generation of dark current resulting therefrom can be suppressed.

[0052] Further, in the present embodiment, the back-in electron shielding portion 20 is provided in a rectangular frame shape with discontinuous corners so as to surround the reflection electron shielding portion 19. By making the back-in electron shielding portion 20 have a discontinuous shape (not a closed shape), when the detection device 1 is used in a vacuum environment, the residual gas inside the back-in electron shielding portion 20 during evacuation of the valve 2 can be preferably suppressed. Therefore, a decrease in the degree of vacuum inside the valve 2 after the valve 2 is vacuum-sealed can be prevented.

[0053] In the present embodiment, the scattered electron shielding portion 18 is made of ceramic. Thereby, the withstand voltage of the scattered electron shielding portion 18 can be sufficiently ensured. By ensuring the withstand voltage of the scattered electron shielding portion 18, the distance between the scattered electron shielding portion 18 and the one surface 13a can be narrowed, and the arrival of the reflected electron Eb at the insulating portion can be more effectively suppressed. Further, in the present embodiment, the reflection electron shielding portion 19 is made of an Au film. Thereby, the degree of freedom of the formation pattern of the reflection electron shielding portion 19 can be easily ensured, and sufficient bonding strength can be obtained even in a small metallized region.

[0054] The present disclosure is not limited to the above-described embodiments. For example, in the above-described embodiments, the reflected electron shielding portion 19 extends over the entire edge Ra of the incident region R. However, the reflected electron shielding portion 19 does not necessarily have to extend over the entire edge Ra of the incident region R, and it may have an extending portion along the edge Ra at least in part. For example, a part of the reflected electron shielding portion 19 may be discontinuous, and a continuous portion and a discontinuous portion may be alternately provided along the edge Ra of the incident region R (that is, the reflected electron shielding portion 19 may be in a broken line shape).

[0055] In the above-described embodiments, the scattered electron shielding portion 18 is made of ceramic. However, the scattered electron shielding portion 18 may be configured by Si (silicon). In this case, the scattered electron shielding portion 18 can be manufactured at low cost. When the scattered electron shielding portion 18 is configured by Si, considering the electrical resistance value of Si (silicon), as shown in FIG. 4, the electrical connection between the n-electrode layer 17 by the recirculating electron shielding portion 20 and the n-conductive layer 23 of the scattered electron shielding portion 18 may be omitted. In this case, a gap between the scattered electron shielding portion 18 and the n-electrode layer 17 can be ensured, and the occurrence of a short circuit between the scattered electron shielding portion 18 and the n-electrode layer 17 can be suppressed. In the configuration of FIG. 4, by directly electrically connecting a conductive wire or the like to the p-electrode layer 16, the n-electrode layer 17, and the p-conductive layer 22, a signal can be extracted through the wire and a voltage can be applied to the detection unit 11.

[0056] In the above-described embodiments, the reflected electron shielding portion 19 is provided singly at the edge Ra of the incident region R. However, as shown in FIG. 5, a mode in which the reflected electron shielding portion 19 is provided multiply at the edge Ra of the incident region R may be adopted. By making the reflected electron shielding portion 19 multiple, the arrival of the reflected electron Eb at the insulating portion can be effectively suppressed.

[0057] In the example of FIG. 5, in addition to the multiple reflection electron shielding portions 19 being provided, the reflection electron shielding portion 19 is composed of a first portion 19A on the p-type semiconductor layer 14 side and a second portion 19B on the scattered electron shielding portion 18 side. Here, the first portion 19A is formed by depositing Au (gold) on the p-electrode layer 16, and the second portion 19B is formed by depositing Au (gold) on the p-conductive layer 22 of the scattered electron shielding portion 18. For the formation of the first portion 19A and the second portion 19B, for example, vapor deposition or plating can be used. The first portion 19A and the second portion 19B may be composed of a conductive adhesive or a metal member.

[0058] In the multiple reflection electron shielding portions 19, the thickness of the first portion 19A and the thickness of the second portion 19B may be equal to each other, or the thickness of the first portion 19A and the thickness of the second portion 19B may be different from each other. The thicknesses of the first portion 19A and the second portion 19B here are the lengths in the direction connecting one surface 13a of the n-type semiconductor layer 13 and one surface 18b of the scattered electron shielding portion 18. In other words, they are the heights in the thickness direction of the substrate 12. In the example of FIG. 5, the reflection electron shielding portion 19 is composed of two layers. In the inner reflection electron shielding portion 19, the thickness of the first portion 19A is larger than the thickness of the second portion 19B, and in the outer reflection electron shielding portion 19, the thickness of the second portion 19B is larger than the thickness of the first portion 19A. On the contrary, in the inner reflection electron shielding portion 19, the thickness of the second portion 19B may be larger than the thickness of the first portion 19A, and in the outer reflection electron shielding portion 19, the thickness of the first portion 19A may be larger than the thickness of the second portion 19B.

[0059] In the example of FIG. 5, as a result of the thickness of the first portion 19A and the thickness of the second portion 19B being different from each other, a slight gap is provided between the first portion 19A and the second portion 19B. According to such a configuration, even when the reflection electron shielding portion 19 is provided over the entire edge Ra of the incident region R, similar to the case where the recirculating electron shielding portion 20 has a discontinuous shape, the residual gas inside the valve 2 (that is, the space sandwiched between the reflection electron shielding portion 19 and the recirculating electron shielding portion 20) during evacuation can be preferably suppressed.

[0060] On the other hand, the first part 19A and the second part 19B may be in contact with each other. In this case, since there is no gap between the first part 19A and the second part 19B, it is possible to more reliably suppress the reflected electrons Eb from reaching the insulating part through this gap. Further, in the configuration where the first part 19A and the second part 19B are in contact with each other, as in the embodiment shown in FIG. 2, the p-type semiconductor layer 14 and the p-conductive layer 22 are electrically connected by the reflected electron shielding part 19. Therefore, it is possible to easily extract the signal from the detection device 1 and apply the potential to the p-type semiconductor layer 14 via the p-conductive layer 22. Further, since the p-type semiconductor layer 14 and the p-conductive layer 22 have the same potential and the charging of the scattered electron shielding part 18 is suppressed, the output signal can be stabilized.

[0061] A configuration may be provided in which both a contact portion where the first part 19A and the second part 19B are in contact and a non-contact portion where the first part 19A and the second part 19B are not in contact are provided. For example, in the circumferential direction of the reflected electron shielding part 19 provided on the entire edge Ra of the incident region R, the contact part and the non-contact part may be alternately provided. In this case, while electrically connecting the p-type semiconductor layer 14 and the p-conductive layer 22 by the reflected electron shielding part 19, it is possible to achieve an effect of suppressing the residual gas inside the valve 2 more than the backflow electron shielding part 20 during evacuation.

[0062] When providing multiple reflected electron shielding parts 19, each of the reflected electron shielding parts 19 does not necessarily have to be continuous over the entire edge Ra of the incident region R, and may be in a state having a discontinuous portion M at least in part. In the example of FIG. 6, discontinuous portions M are provided in each of the inner reflected electron shielding part 19 and the outer reflected electron shielding part 19. And the inner reflected electron shielding part 19 and the outer reflected electron shielding part 19 are arranged so that the discontinuous portions M do not face each other in the radial direction.

[0063] According to such a configuration, since the reflection electron shielding part 19 is multiplexed, even when a discontinuous part M is provided in each of the multiplexed reflection electron shielding parts 19, it is possible to effectively suppress the reflected electron Eb from reaching the insulating part. Further, by not making the discontinuous parts M of the multiplexed reflection electron shielding parts 19 face each other in the radial direction, when the detection device 1 is used in a vacuum environment, the residual gas in the vicinity of the reflection electron shielding part 19 (the space sandwiched between the inner reflection electron shielding part 19 and the outer reflection electron shielding part 19) can be preferably suppressed.

[0064] Further, as shown in FIG. 7, the scattered electron shielding part 18 may also serve as the reflection electron shielding part 19. In this case, the reflection electron shielding part 19 can be configured with a simple structure. In the example of FIG. 7, the entire edge 18d of the opening 18a of the scattered electron shielding part 18 protrudes toward the one surface 13a side corresponding to the edge Ra of the incident region R, and the edge 18d functions as the reflection electron shielding part 19. In the example of FIG. 7, the p-conductive layer 22 is also continuous on the surface of the edge 18da, and the p-conductive layer 22 is in direct contact with the p-type semiconductor layer 14, so that the p-type semiconductor layer 14 and the p-conductive layer 22 are electrically connected.

[0065] Note that also in the example of FIG. 7, similar to the embodiment shown in FIG. 2, the reflection electron shielding part 19 made of an Au film electrically connects the p-electrode layer 16 and the p-conductive layer 22. In this case, the edge 18d of the scattered electron shielding part 18 becomes the inner reflection electron shielding part 19, and the Au film that electrically connects the p-type semiconductor layer 14 and the p-conductive layer 22 becomes the outer reflection electron shielding part 19. Therefore, the reflection electron shielding part 19 is multiplexed, and it is possible to effectively suppress the reflected electron Eb from reaching the insulating part.

[0066] As shown in FIG. 7, when the edge 18d of the opening 18a of the scattered electron shielding portion 18 protrudes toward the one surface 13a side, the p-conductive layer 22 does not necessarily have to be in contact with the p-type semiconductor layer 14. In this case, since a gap is generated between the p-conductive layer 22 and the p-type semiconductor layer 14, when the detection device 1 is used in a vacuum environment, the residual gas between the inner and outer reflection electron shielding portions 19 can be preferably suppressed. Further, as shown in FIG. 7, when the edge 18d of the opening 18a of the scattered electron shielding portion 18 protrudes toward the one surface 13a side, the reflection electron shielding portion 19 made of an Au film may be omitted. In this case, the configuration of the detection device 1 can be further simplified.

Explanation of Signs

[0067] 1... Detection device, 13... n-type semiconductor layer (first semiconductor layer), 13a... One surface, 14... p-type semiconductor layer (second semiconductor layer), 15... Insulating layer (insulating portion), 16... p-electrode layer (second electrode layer), 17... n-electrode layer (first electrode layer), 18... Scattered electron shielding portion (first shielding portion), 18a... Opening, 18d... Edge (second shielding portion), 19... Reflection electron shielding portion (second shielding portion), 19A... First portion, 19B... Second portion, 20... Recirculating electron shielding portion (third shielding portion), 21... Passivation layer (insulating portion), 22... p-conductive layer (first conductive layer), E... Electron (charged particle), K... pn junction region, R... Incident region, Ra... Edge, M... Discontinuous portion.

Claims

1. a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type, provided so as to be exposed on one surface of the first semiconductor layer and forming a pn junction region with the first semiconductor layer; a first electrode layer electrically connected to the first semiconductor layer; a second electrode layer electrically connected to the second semiconductor layer; an insulating portion covering the pn junction region so that a part of the second semiconductor layer is exposed as an incident region of charged particles and electrically insulating the first electrode layer and the second electrode layer; a first shielding portion having an opening for exposing the incident region and disposed on the one surface side so that the insulating portion is not exposed from the opening in a plan view of the one surface; a detection device, wherein a second shielding portion that partitions the incident region and the insulating portion in a plan view of the one surface extends along the edge of the incident region.

2. The detection device according to claim 1, wherein the second shielding portion extends over the entire edge of the incident region.

3. The first shielding portion has a first conductive layer corresponding to the second semiconductor layer, The detection device according to claim 1, wherein the second shielding portion is made of a conductive material and electrically connects the second semiconductor layer and the first conductive layer.

4. The detection device according to claim 1, wherein the second shielding portion is composed of a first portion on the second semiconductor layer side and a second portion on the second shielding portion side.

5. The second shielding portion is configured in multiple layers, The detection device according to claim 4, wherein in the multiple second shielding portions, the thickness of the first portion and the thickness of the second portion are different from each other.

6. The second shielding portion is configured in multiple layers with at least a part having a discontinuous portion, The detection device according to claim 1, wherein the multiple second shielding portions are arranged such that the discontinuous portions do not face each other.

7. The detection device according to claim 1, wherein the second shielding portion is formed by the edge of the opening of the first shielding portion protruding to the one surface side.

8. The detection device according to claim 1, wherein in a plan view of the one surface, a third shielding portion is provided in a region outside the second shielding portion to partition the insulating portion between the second shielding portion and the region outside it.

9. The first shielding portion has a second conductive layer corresponding to the first semiconductor layer, The detection device according to claim 8, wherein the third shielding portion is made of a conductive material and electrically connects the first semiconductor layer and the second conductive layer.

10. The detection device according to any one of claims 1 to 9, wherein the first shielding portion is made of ceramic.

11. The detection device according to any one of claims 1 to 9, wherein the first shielding portion is made of Si.

12. The detection device according to any one of claims 1 to 9, wherein the second shielding portion is made of Au.

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