Charged particle detector

Abstract

To provide a charged particle detector that can suppress the effect on the time response characteristics of a conductor detector and prevent a semiconductor detector from being adversely affected when a discharge occurs.SOLUTION: A charged particle detector 1 includes a semiconductor detector 3 including an anode 3a and a cathode 3b, in which a first voltage is supplied to the cathode 3b and a second voltage lower than the first voltage is supplied to the anode 3a, a conductor portion 8 connected to a reference potential GND that is a potential lower than the second voltage, and a protective portion 6 that is disposed between the anode 3a and the conductor portion 8 and to which a low potential that is a potential with an absolute value lower than that of the second voltage is applied. The protective portion 6 has a resistor 62.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a charged particle detector for detecting ions, electrons, etc. The charged particle detector according to the present disclosure is used, for example, in mass spectrometry. [Background technology]

[0002] A known charged particle detector for detecting charged particles such as ions and electrons has an electron multiplier element that emits electrons in response to the incidence of a charged particle, and a semiconductor detector that captures the emitted electrons and outputs them as an electric signal (see, for example, Patent Document 1). The charged particle detector described in Patent Document 1 includes an avalanche diode (AD) as the semiconductor detector, and a capacitor is connected in series to the AD to reduce the combined capacitance with the AD capacitance, thereby achieving a high-speed response of the AD.

[0003] An input protection circuit for protecting elements of an input circuit from overvoltage caused by discharge or the like is known (see, for example, Patent Document 2). The input protection circuit described in Patent Document 2 includes an ESD protection element and a resistor. By connecting a surge-proof resistor on the signal path, it is possible to prevent an overcurrent from being input to the input circuit at the subsequent stage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-81982 [Patent Document 2] WO 2008 / 53555 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned charged particle detector, a discharge may occur between the semiconductor detector and the reference potential, and a large current may instantaneously flow through the semiconductor detector due to the discharge. Such a discharge current may adversely affect the semiconductor detector.

[0006] When the input protection circuit described in Patent Document 2 is applied to a semiconductor detector in order to prevent adverse effects on the semiconductor detector, a resistor connected in the signal path may affect the time response characteristics of the semiconductor detector.

[0007] An object of the present disclosure is to provide a charged particle detector that can suppress the effect on the time response characteristics of a semiconductor detector and prevent the semiconductor detector from being adversely affected when a discharge occurs. [Means for solving the problem]

[0008] A charged particle detector according to one aspect of the present disclosure comprises a semiconductor detector 3 including an anode and a cathode, in which a first voltage is supplied to the cathode and a second voltage lower than the first voltage is supplied to the anode, a conductor portion connected to a reference potential GND, which is a potential having an absolute value lower than that of the second voltage, and a protective portion disposed between the anode and the conductor portion and to which a low potential, which is a potential having an absolute value lower than that of the second voltage, is applied, the protective portion having a resistor.

[0009] In the charged particle detector, the semiconductor detector is supplied with a high reverse bias voltage, so that a current flows from the cathode to the anode. The protective unit is disposed between the anode and the conductor, and a low potential having an absolute value lower than that of the second voltage is applied to the protective unit. Therefore, discharge occurs more easily between the semiconductor detector and the protective unit than between the semiconductor detector and the conductor, and the discharge current flows from the semiconductor detector having a high potential to the protective unit having a low potential. Furthermore, the protective unit includes a resistor, so that the discharge current can be reduced. This reduces the current flowing through the semiconductor detector when a discharge occurs, and prevents the semiconductor detector from being adversely affected. In addition, in the charged particle detector, the resistor is not connected in the middle of the signal output path, so that the influence of the resistor on the time response characteristics of the semiconductor detector can be suppressed.

[0010] The protection section may further include a protection electrode to which a low potential is applied via a resistor. In this case, since the protection electrode is located closer to the semiconductor detector than the conductor section, discharge is more likely to occur preferentially between the semiconductor detector and the protection electrode than between the semiconductor detector and the conductor section, and the discharge current is more likely to flow toward the protection electrode. This makes it easier to ensure a discharge path for the discharge current via the protection electrode and the resistor.

[0011] The low potential is a reference potential, the conductor portion includes an outer conductor connected to the reference potential and a central conductor inserted inside the outer conductor, and has a connector connected to the semiconductor detector, and the protection portion may be connected to the outer conductor. In this case, the discharge current flows from the semiconductor detector through the protection portion and the outer conductor of the conductor portion to the reference potential. Meanwhile, the electrical signal (output signal) output from the semiconductor detector is output to the outside by the central conductor. This eliminates the need to provide an additional element as a destination for the discharge current, and therefore makes it possible to efficiently ensure a discharge path for the discharge current.

[0012] The low potential may be a reference potential, the conductor portion may include an outer conductor connected to the reference potential, and the protective portion may be a resistive film covering the outer conductor. In this case, since the protective portion is a resistive film, it is not necessary to provide a resistor as, for example, a resistive element, and wiring connecting the protective electrode and the resistor to a low potential supply source is not required, so that the discharge path of the discharge current can be configured simply.

[0013] The low potential may be a potential having an absolute value higher than that of the reference potential and lower than that of the second voltage, which increases the degree of freedom in designing the low potential.

[0014] The semiconductor detector may further include a substrate on which the semiconductor detector, the protective part, and the conductor part are mounted, the semiconductor detector being mounted on a main surface of the substrate, and the protective part and the conductor part being mounted on a back surface opposite to the main surface. In this case, by mounting the protective part on the back surface, which is the surface opposite to the semiconductor detector, it is possible to suppress the potential of the protective part from becoming unstable when a discharge occurs, and to more safely flow the discharge current from the semiconductor detector to the protective part.

[0015] The semiconductor detector may further include a substrate on which the semiconductor detector and the protection unit are mounted, and a housing for accommodating the substrate, and the conductor may be the housing. In this case, the discharge current can be directed toward the housing outside the substrate, thereby preventing adverse effects on the semiconductor detector mounted on the substrate.

[0016] An analysis device according to an aspect of the present disclosure may include the above-mentioned charged particle detector and a signal processing unit that processes an electrical signal output from the charged particle detector. In this case, in the analysis device, similar to the charged particle detector, the current flowing through the semiconductor detector when a discharge occurs is reduced, and it is possible to prevent adverse effects on the semiconductor detector.

[0017] The charged particle detector disclosed herein is [1] "a charged particle detector comprising: a semiconductor detector including an anode and a cathode, the cathode being supplied with a first voltage and the anode being supplied with a second voltage lower than the first voltage; a conductor portion connected to a reference potential having an absolute value lower than that of the second voltage; and a protective portion disposed between the anode and the conductor portion and to which a low potential having an absolute value lower than that of the second voltage is applied, the protective portion having a resistor."

[0018] The charged particle detector of the present disclosure may be [2] "the charged particle detector described in [1] above, wherein the protective section further has a protective electrode to which the low potential is applied via the resistor."

[0019] The charged particle detector of the present disclosure may be [3] "a charged particle detector as described in [1] or [2], wherein the low potential is the reference potential, the conductor portion includes an outer conductor connected to the reference potential and a central conductor inserted inside the outer conductor, has a connector connected to the semiconductor detector, and the protective portion is connected to the outer conductor."

[0020] The charged particle detector of the present disclosure may be [4] "the charged particle detector described in [1] above, wherein the low potential is the reference potential, the conductor portion includes an outer conductor connected to the reference potential, and the protective portion is a resistive film covering the outer conductor."

[0021] The charged particle detector of the present disclosure may be [5] "the charged particle detector described in [1] or [2], wherein the low potential is a potential with an absolute value higher than the absolute value of the reference potential and a potential with an absolute value lower than the absolute value of the second voltage."

[0022] The charged particle detector of the present disclosure may be [6] "the charged particle detector according to any one of [1] to [5] above, further comprising a substrate on which the semiconductor detector, the protective portion, and the conductor portion are mounted, the semiconductor detector being mounted on a main surface of the substrate, and the protective portion and the conductor portion being mounted on a back surface opposite the main surface."

[0023] The charged particle detector of the present disclosure may be [7] "the charged particle detector described in [1] or [2], further comprising a substrate on which the semiconductor detector and the protective part are mounted, and a housing for accommodating the substrate, wherein the conductor part is the housing."

[0024] The analytical device of the present disclosure may be [8] "an analytical device including a charged particle detector according to any one of [1] to [7] and a signal processing unit that processes an electrical signal output from the charged particle detector." Effect of the Invention

[0025] According to the present disclosure, it is possible to suppress the influence on the time response characteristics of a semiconductor detector, and to prevent the semiconductor detector from being adversely affected when a discharge occurs. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram for explaining a schematic configuration of a charged particle detector according to this embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic circuit diagram of a charged particle detector. [Diagram 3] Fig. 3(a) is a diagram for explaining a discharge path of a discharge current in a charged particle detector according to a comparative example, and Fig. 3(b) is a diagram for explaining a discharge path of a discharge current in a charged particle detector according to the present embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a substrate in a charged particle detector. [Diagram 5] Fig. 5(a) is a plan view of the substrate as viewed from the main surface side, and Fig. 5(b) is a plan view of the substrate as viewed from the back surface side. [Figure 6] Fig. 6(a) is a cross-sectional view of a substrate in a charged particle detector according to a first modified example, and Fig. 6(b) is a plan view of the substrate in a charged particle detector according to a second modified example, viewed from the back surface side. [Figure 7] FIG. 7 is a cross-sectional view of a substrate in a charged particle detector according to a third modified example. [Figure 8] FIG. 8 is a cross-sectional view of a substrate in a charged particle detector according to a fourth modified example. [Figure 9] FIG. 9 is a diagram for explaining a schematic configuration of the analysis device 10. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will 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. [Embodiment]

[0028] 1 is a diagram for explaining a schematic configuration of a charged particle detector 1 according to this embodiment. The charged particle detector 1 is a detector that detects charged particles such as ions and electrons. The charged particle detector 1 includes an electron multiplier element 2, a semiconductor detector 3, a power supply unit 4, a signal output unit 5, and a protection unit 6.

[0029] The electron multiplier element 2 emits electrons E1 in response to the incidence of charged particles such as ions and electrons. The electron multiplier element 2 is, for example, a microchannel plate. When a charged particle is incident on the input surface of the electron multiplier element 2, the electron multiplier element 2 generates electrons E1 in response to the charged particle, cascade-multiplies the electrons E1, and emits them from the output surface. The emitted electrons E1 are accelerated by an acceleration electrode (not shown), focused by a focus electrode (not shown), and then enter the semiconductor detector 3.

[0030] The semiconductor detector 3 captures the focused electrons E1 and outputs them as an output signal S1. In this embodiment, the semiconductor detector 3 is composed of an avalanche diode (AD). The semiconductor detector 3 is mounted on the main surface of a substrate described later. The AD includes a laminated structure in which a P-type semiconductor layer and an N-type semiconductor layer are laminated. The semiconductor detector 3 includes an anode 3a and a cathode 3b. The anode 3a faces the output surface of the electron multiplier element 2. The anode 3a is an electrode on the P-type semiconductor layer side in the AD. The electrons E1 are incident on the anode 3a. The cathode 3b faces the main surface of the substrate. The cathode 3b is an electrode on the N-type semiconductor layer side in the AD. The output signal S1 is output from the cathode 3b.

[0031] The power supply unit 4 generates a first voltage V1 and a second voltage V2 for driving the semiconductor detector 3. FIG. 2 is a circuit diagram showing a schematic configuration of the charged particle detector 1. In FIG. 2, the electron multiplier element 2 is omitted. In FIG. 2, the semiconductor detector 3 is shown as an equivalent circuit composed of a diode and a parasitic capacitance connected in parallel to the diode. As shown in FIG. 2, the power supply unit 4 includes a power supply Vcc, a power supply unit Vin, resistors R1 to R6, and a diode D1. The negative electrode of the power supply Vcc is connected to one end of the resistor R1, and the positive electrode of the power supply Vcc is connected to the other end of the resistor R4. The resistors R1 to R4 are connected in series with each other. The node between the resistors R2 and R3 is connected to the anode 3a via the resistor R5. The other end of the resistor R4 is connected to the cathode 3b via the resistor R6.

[0032] The power supply unit 4 generates a high voltage of several kV to several tens of kV at the power supply Vcc. In this embodiment, the power supply unit 4 generates a positive high voltage at the power supply Vcc. The resistors R1 to R4 divide the generated high voltage, and apply a first voltage V1 to the cathode 3b via the resistor R6, and apply a second voltage V2 to the anode 3a via the resistor R5. The first voltage V1 is higher than the second voltage V2. The first voltage V1 is, for example, 10 kV, and the second voltage V2 is, for example, 9.65 kV. Therefore, a voltage (reverse bias) of, for example, 350 V is applied between the anode 3a and the cathode 3b of the semiconductor detector 3, and the semiconductor detector 3 operates in a floating state. In the power supply unit 4, the resistors R5 and R6 are current limiting resistors that limit the current input to the semiconductor detector 3. The diode D1 is connected in parallel with the resistor R6, and is a TVS diode that protects the cathode 3b from surge voltages and the like.

[0033] The power supply unit Vin generates a voltage to be supplied to the input surface of the electron multiplier element 2. The negative electrode of the power supply unit Vin is connected to the input surface (not shown) of the electron multiplier element 2, and the positive electrode of the power supply unit Vin is connected to the reference potential GND.

[0034] The reference potential GND described in this embodiment and the modified examples is a common reference potential and has the same potential, so that no potential difference occurs between the reference potentials, and the semiconductor detector 3 operates stably.

[0035] The signal output unit 5 outputs the output signal S1 output from the semiconductor detector 3 to the outside. The output signal S1 is an AC signal, for example, a pulse wave that repeats a Hi level and a Low level at a predetermined period. As shown in FIG. 2, the signal output unit 5 includes capacitors C1 and C2, resistors R7, R8, and Re, and a signal output terminal 51. The capacitor C1 is connected between the cathode 3b and the signal output terminal 51. The capacitor C1 is a coupling capacitor that cuts the DC component of the output signal S1 output from the cathode 3b and extracts only the AC signal. A measuring device such as an oscilloscope for measuring the output signal S1 is connected to the signal output terminal 51. The resistor Re is connected between the signal output terminal 51 and the reference potential GND as a terminating resistor for impedance matching.

[0036] One end of the capacitor C2 is connected to the anode 3a. A resistor R7 is connected between the other end of the capacitor C2 and the reference potential GND. This forms a return path between the anode 3a and the reference potential GND. If electrons continue to be incident on the semiconductor detector 3, a voltage drop occurs at the electron incident surface of the semiconductor detector 3. In this case, the output signal S1 output from the semiconductor detector 3 to the signal output terminal 51 reflects the fluctuation of the DC component caused by this voltage drop. Therefore, by disposing the capacitor C2 between the anode 3a and the reference potential GND, the fluctuation of the DC component reflected in the output signal S1 is canceled. In addition, the capacitor C2 makes it possible to return the output signal S1 output from the cathode 3b to the signal output terminal 51 to the anode 3a via the return path with low impedance. The resistor R7 is a damping resistor for further suppressing the fluctuation of the DC component reflected in the output signal S1. In addition, a resistor R8 is connected between the signal output terminal 51 and the reference potential GND. The resistor R8 is a current limiting resistor for preventing an overcurrent from flowing into the anode 3a via the return path.

[0037] When a discharge occurs between the semiconductor detector 3 and the reference potential GND, the protection unit 6 induces and suppresses a discharge current I1 flowing through the semiconductor detector 3. In this embodiment, the reference potential GND is a potential lower than the second voltage V2. As shown in FIG. 2, the protection unit 6 is disposed between the anode 3a and the reference potential GND. The protection unit 6 includes a protection electrode 61 and a resistor 62. The protection electrode 61 is connected to the reference potential GND via the resistor 62. The protection electrode 61 is disposed at a predetermined interval from the anode 3a. In other words, the protection electrode 61 is disposed electrically and physically separated from the semiconductor detector 3. The protection electrode 61 induces the discharge current I1 so that the discharge current I1 flows to the protection electrode 61 side. The resistor 62 is a high-voltage resistance resistor and reduces the discharge current I1. Here, if the reference potential GND is rephrased as a low potential, which is a potential with an absolute value lower than the absolute value of the second voltage, it can be considered that a low potential is applied to the protection unit 6, and a low potential is applied to the protection electrode 61 via the resistor 62.

[0038] Next, the effect of providing the protective unit 6 will be described with reference to FIG. 3. FIG. 3(a) is a diagram for explaining the discharge path of the discharge current I1 in a charged particle detector according to a comparative example not including the protective unit 6. When a discharge occurs between the semiconductor detector 3 and the reference potential GND, for example, it is assumed that a dielectric breakdown occurs between the anode 3a and the reference potential GND, and a short circuit occurs between the anode 3a and the reference potential GND. In this case, the discharge current I1 flows from the cathode 3b to the semiconductor detector 3 starting from the resistor Re side. Then, the discharge current I1 flowing out from the anode 3a flows through the short circuit path formed between the anode 3a and the reference potential GND. For example, when a discharge voltage of 10 kV occurs, the discharge current I1 becomes 200 A obtained by dividing the voltage value of the discharge voltage by the resistance value (for example, 50 Ω) of the resistor Re, and a large current of 200 A flows in the semiconductor detector 3 in the reverse bias direction, which may adversely affect the semiconductor detector 3.

[0039] FIG. 3(b) is a diagram for explaining the discharge path of the discharge current I1 in the charged particle detector 1 according to the present embodiment. In FIG. 3(b), discharge is more likely to occur between the semiconductor detector 3 and the protective unit 6 than between the semiconductor detector 3 and the reference potential GND. In this case, for example, it is assumed that a dielectric breakdown occurs between the anode 3a and the protective electrode 61, and a short circuit occurs between the anode 3a and the protective electrode 61. In this case, the discharge current I1 flows from the cathode 3b to the semiconductor detector 3 starting from the resistor Re side. Then, the discharge current I1 flowing out from the anode 3a flows through the short circuit path formed between the anode 3a and the protective electrode 61. The discharge current I1 flows to the reference potential GND through the protective electrode 61 and the resistor 62. For example, when a discharge voltage of 10 kV occurs, if the resistance value of the resistor 62 is 1 MΩ, the discharge current I1 is reduced to 10 mA. As a result, the influence on the semiconductor detector 3 is significantly reduced compared to when the protective electrode 61 is not provided.

[0040] Next, the arrangement of the semiconductor detector 3 and the protective part 6 will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a cross-sectional view of the substrate 7 in the charged particle detector 1. Fig. 5(a) is a plan view of the substrate 7 seen from the main surface 7a side. Fig. 5(b) is a plan view of the substrate 7 seen from the back surface 7b side.

[0041] As shown in FIG. 4, the charged particle detector 1 further includes a substrate 7 and a conductor portion 8. The substrate 7 includes a main surface 7a and a back surface 7b opposite to the main surface 7a. The semiconductor detector 3 is mounted on the main surface 7a. The protective portion 6 is mounted on the back surface 7b. The substrate 7 is, for example, a printed wiring board. The substrate 7 includes a plurality of copper foil layers inside. The plurality of copper foil layers are provided at two locations along the in-plane direction of the substrate 7, and at each location, the plurality of copper foil layers are laminated along the thickness direction of the substrate 7. Among the plurality of copper foil layers, a predetermined space is provided between the first copper foil layer closest to the main surface 7a and the second copper foil layer closest to the second copper foil layer, and a stray capacitance component is formed in the space. The stray capacitance component formed in the first plurality of copper foil layers forms a capacitor C1, and the stray capacitance component formed in the second plurality of copper foil layers forms a capacitor C2. Of the multiple copper foil layers, the second and subsequent copper foil layers are electrically connected to each other, so no stray capacitance is formed.

[0042] As shown in FIG. 5(a), the capacitor C1 is connected to the cathode 3b at the conductive electrode pattern P1. The capacitor C1 is also connected to one end of the resistor R6 at the electrode pattern P2. The other end of the resistor R6 is connected to the electrode pattern P3. The electrode pattern P3 is connected to the other end of the resistor R4 shown in FIG. 2. The capacitor C2 is connected to the anode 3a at the conductive electrode pattern P4. The capacitor C2 is also connected to one end of the resistor R5 at the electrode pattern P5. The other end of the resistor R5 is connected to the electrode pattern P6. The electrode pattern P6 is connected to a node between the resistor R2 and the resistor R3 shown in FIG. 2. In addition, the elements of the power supply unit 4 that are not shown in FIG. 5(a) other than the resistor R5, the resistor R6, and the diode D1 may be disposed on or outside the substrate 7.

[0043] As shown in FIG. 4, the conductor 8 is mounted on the back surface 7b of the substrate 7. In this embodiment, the conductor 8 is composed of a connector 83. The connector 83 is, for example, an SMA jack. The connector 83 is connected to the semiconductor detector 3 via the substrate 7. The connector 83 includes a cylindrical outer conductor 81 and a central conductor 82 that passes through the inside of the outer conductor 81. The central axis of the semiconductor detector 3 and the central axis of the outer conductor 81 coincide with each other. The central conductor 82 is provided so as to pass through the central axis of the outer conductor 81. The outer surface of the outer conductor 81 is connected to the reference potential GND. One end of the central conductor 82 is connected to the capacitor C1 via the substrate 7. The other end of the central conductor 82 is connected to the signal output terminal 51. The capacitor C1, the central conductor 82, and the signal output terminal 51 configure a signal output path that outputs a signal from the semiconductor detector 3 (cathode 3b).

[0044] The protective portion 6 is disposed midway along the creeping surface connecting the anode 3a on the main surface 7a of the substrate 7 and the conductor portion 8 on the back surface 7b. That is, the protective portion 6 is located closer to the semiconductor detector 3 than the conductor portion 8. Specifically, as shown in FIG. 5(b), the protective electrode 61 is formed on the back surface 7b along the outer edge of the substrate 7, surrounding the conductor portion 8, the resistors R7, R8, and the resistor 62. One end of the resistor 62 is connected to the protective electrode 61 via the wiring pattern P7, and the other end of the resistor 62 is connected to the peripheral conductor 81 via the wiring pattern P8. This makes it easier for discharge to occur between the anode 3a and the protective electrode 61 than between the anode 3a and the peripheral conductor 81. In this case, when discharge occurs, insulation breakdown occurs between the anode 3a and the protective electrode 61, and the anode 3a and the protective electrode 61 are short-circuited. The amount of discharge current I1 induced in the protective electrode 61 that flows when a discharge occurs is suppressed by the resistor 62, and the discharge current I1 flows to the reference potential GND via the peripheral conductor 81. [Action and Effects]

[0045] In the charged particle detector 1 described above, since a high reverse bias voltage is supplied to the semiconductor detector 3, a current flows from the cathode 3b to the anode 3a. When a discharge occurs between the semiconductor detector 3 and the conductor 8, the charge of the capacitor C1 flows in reverse bias to the semiconductor detector 3 as a discharge current I1. The protective unit 6 is disposed between the anode 3a and the conductor 8, and a low potential having an absolute value lower than the absolute value of the second voltage V2 is applied to the protective unit 6, so that the discharge current I1 flows from the semiconductor detector 3 having a high potential to the protective unit 6 having a low potential. Furthermore, since the protective unit 6 includes a resistor 62, the discharge current I1 can be reduced. This reduces the discharge current I1 flowing to the semiconductor detector 3 when a discharge occurs, and prevents adverse effects such as deterioration and damage caused by a large current flowing in the reverse bias direction to the semiconductor detector 3. In addition, in the charged particle detector 1, since the resistor 62 is not connected in the middle of the signal output path, it is possible to employ a resistor with a resistance value large enough to protect the semiconductor detector 3, while suppressing the effects on characteristics such as a decrease in the time response characteristics (high-speed response) of the semiconductor detector 3.

[0046] The protection section 6 further includes a protection electrode 61 to which a low potential (reference potential GND) is applied via a resistor 62. In this case, since the protection electrode 61 is located closer to the semiconductor detector 3 than the conductor section 8, the protection electrode 61 is more susceptible to discharge, and the discharge current I1 is more likely to flow toward the protection electrode 61. This makes it easier to ensure a discharge path for the discharge current I1 via the protection electrode 61 and the resistor 62.

[0047] The low potential applied to the protection unit 6 is the reference potential GND, and the conductor unit 8 includes an outer conductor 81 connected to the reference potential GND and a central conductor 82 inserted inside the outer conductor 81, has a connector 83 connected to the semiconductor detector 3, and the protection unit 6 is connected to the outer conductor 81. In this case, the discharge current I1 flows from the semiconductor detector 3 through the protection unit 6 and the outer conductor 81 of the conductor unit 8 to the reference potential GND. On the other hand, the output signal S1 output from the semiconductor detector 3 is output to the outside by the central conductor 82. As a result, there is no need to provide an additional element as a destination for the discharge current I1, and therefore a discharge path for the discharge current I1 can be efficiently secured.

[0048] The device further includes a substrate 7 on which the semiconductor detector 3, the protective unit 6, and the conductor unit 8 are mounted, and the semiconductor detector 3 is mounted on a main surface 7a of the substrate 7, and the protective unit 6 and the conductor unit 8 are mounted on a back surface 7b opposite to the main surface 7a. In this case, by mounting the protective unit 6 on the back surface 7b, which is the surface opposite to the semiconductor detector 3, it is possible to prevent the potential of the protective unit 6 from becoming unstable when a discharge occurs, and it is possible to more safely flow the discharge current I1 from the semiconductor detector 3 to the protective unit 6. [Variations]

[0049] Although the embodiments of the present disclosure have been described above, the present disclosure is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present disclosure.

[0050] FIG. 6(a) is a cross-sectional view of the substrate 7 in the charged particle detector 1A according to the first modification. FIG. 6(b) is a plan view of the substrate 7 in the charged particle detector 1B according to the second modification, viewed from the back surface 7b side. The protective portion 6A included in the charged particle detector 1A and the protective portion 6B included in the charged particle detector 1B are different from the protective portion 6 in that they do not include a protective electrode 61 and include a resistive film as the resistor 62 instead of a resistive element. The resistive film includes, for example, powder of an inorganic material such as a metal oxide and a binder (welding agent, binding agent). As shown in FIG. 6(a), in the protective portion 6A, the resistor 62 is formed so as to cover the outer surface of the peripheral conductor 81. As shown in FIG. 6(b), in the protective portion 6B, the resistor 62 is formed around the conductor portion 8 so as to cover a part of the back surface 7b. Also in the protective parts 6A and 6B, the resistor 62 is located closer to the semiconductor detector 3 than the conductor part 8, so that the protective parts 6A and 6B are more susceptible to discharge, and the discharge current I1 is suppressed by the resistor 62 and flows to the reference potential GND via the outer conductor 81. Also, since the protective parts 6A and 6B include a resistive film as the resistor 62, it is not necessary to provide the resistor 62 as a resistive element, and further, wiring for connecting the protective electrode 61 and the resistor 62 to a low potential supply source (for example, the reference potential GND) is not required, so that the discharge path of the discharge current I1 can be configured simply.

[0051] The conductor connected to the resistor 62 of the protective section 6 may be composed of something other than the connector 83. FIG. 7 is a cross-sectional view of the substrate 7 in a charged particle detector 1C according to a third modification. The charged particle detector 1C further includes a conductive housing 9 that houses the substrate 7. The housing 9 is connected to a reference potential GND. In the charged particle detector 1C, the conductor 8A is composed of the housing 9. In the example of FIG. 7, the protective electrode 61 is mounted on the main surface 7a. As a result, the protective electrode 61 is located closer to the semiconductor detector 3 than the conductor 8A. The protective electrode 61 may be connected to the resistor 62 through a via V that penetrates from the main surface 7a to the back surface 7b and a wiring pattern P7. The other end of the resistor 62 is connected to the housing 9 through a wiring pattern P8. In this case, the discharge current I1 flows to the reference potential GND through the housing 9. As shown in FIG. 7, the substrate 7 is fixed so as to be fitted into the inner surface of the housing 9, and the back surface 7b may be exposed to the outside. Alternatively, the housing 9 may include a bottom surface with an opening formed on the bottom surface. The substrate 7 may be placed on the bottom surface with the connector 83 exposed to the outside through the opening. In the charged particle detector 1C, the discharge current I1 can be caused to flow toward the housing 9 outside the substrate 7, so that adverse effects on the semiconductor detector 3 mounted on the substrate 7 can be reliably prevented.

[0052] The conductor is not limited to the connector 83 and the housing 9. For example, the housing of a device other than the charged particle detector 1 may be the conductor. The other device may be, for example, a vacuum chamber that puts the charged particle detector 1 in a vacuum state. Alternatively, the conductor may be a member within the charged particle detector 1 and connected to the reference potential GND. In either case, the discharge current I1 can be caused to flow toward the outside of the substrate 7.

[0053] FIG. 8 is a cross-sectional view of the substrate 7 in a charged particle detector 1D according to a fourth modification. The charged particle detector 1D is different from the charged particle detector 1 in that the protective unit 6 is connected to the low voltage source Vcc2, not to the reference potential GND. The other end of the resistor 62 is connected to the low voltage source Vcc2. A potential is applied to the protective unit 6 from the low voltage source Vcc2, and a potential is applied to the protective electrode 61 from the low voltage source Vcc2 via the resistor 62. The potential applied from the low voltage source Vcc2 is a potential with an absolute value lower than that of the second voltage V2 and higher than that of the reference potential GND. Even in this case, the discharge current I1 flows from the semiconductor detector 3 with a high potential to the protective unit 6 with a low potential. Furthermore, the charged particle detector 1D improves the degree of freedom in designing the potential applied to the protective unit 6.

[0054] The power supply unit 4 may generate a negative high voltage at the power supply Vcc. In this case, in a state where a negative high voltage is applied between the anode 3a and the cathode 3b of the semiconductor detector 3, a reverse bias is applied between the anode 3a and the cathode 3b, and the semiconductor detector 3 operates in a floating state. Even when a negative high voltage is applied between the anode 3a and the cathode 3b of the semiconductor detector 3, a low potential, which is a potential with an absolute value lower than the absolute value of the second voltage V2, is applied to the protection unit 6, so that the discharge current I1 flows from the protection unit 6 with a high potential to the semiconductor detector 3 with a low potential.

[0055] The charged particle detectors 1 to 1D described in the embodiments and modifications may be used in an analysis device. FIG. 9 is a diagram for explaining a schematic configuration of an analysis device 10. The analysis device 10 may include the charged particle detectors 1 to 1D and a signal processing unit 20 that processes an electric signal (output signal S1) output from the charged particle detectors 1 to 1D. The analysis device 10 is, for example, a mass spectrometer. In this case, the signal processing unit 20 may generate a mass spectrum based on the output signal S1. In addition, when the analysis device 10 is a mass spectrometer, the target detected by the charged particle detectors 1 to 1D is ions. The polarity of the voltage applied to the semiconductor detector 3 may be selected depending on whether the charged particle detectors 1 to 1D detect positive or negative ions. For example, when the charged particle detectors 1 to 1D detect negative ions, a positive high voltage may be applied between the anode 3a and the cathode 3b of the semiconductor detector 3. Alternatively, when the charged particle detectors 1 to 1D detect positive ions, a negative high voltage may be applied between the anode 3a and the cathode 3b of the semiconductor detector 3. In the analysis device 10, similarly to the charged particle detectors 1 to 1D, the current flowing through the semiconductor detector 3 when a discharge occurs is reduced, and it is possible to prevent the semiconductor detector 3 from being adversely affected. [Explanation of symbols]

[0056] 1, 1A, 1B, 1C, 1D...charged particle detector, 10...analytical device, 20...signal processing unit, 3...semiconductor detector, 3a...anode, 3b...cathode, 6, 6A, 6B...protective unit, 61...protective electrode, 62...resistor, 7...substrate, 7a...main surface, 7b...rear surface, 8, 8A...conductor portion, 9...housing, 81...peripheral conductor, 82...central conductor, 83...connector, GND...reference potential, V1...first voltage, V2...second voltage.

Claims

1. a semiconductor detector including an anode and a cathode, the cathode being supplied with a first voltage and the anode being supplied with a second voltage lower than the first voltage; a conductor portion connected to a reference potential having an absolute value lower than the absolute value of the second voltage; a protection section disposed between the anode and the conductor section, to which a low potential having an absolute value lower than that of the second voltage is applied; The protective portion includes a resistor.

2. The charged particle detector according to claim 1 , wherein the protection section further comprises a protection electrode to which the low potential is applied via the resistor.

3. the low potential is the reference potential, the conductor portion includes an outer conductor connected to the reference potential and a central conductor passing through the outer conductor, and has a connector connected to the semiconductor detector; The charged particle detector according to claim 1 , wherein the protective portion is connected to the outer circumferential conductor.

4. the low potential is the reference potential, the conductor portion includes an outer conductor connected to the reference potential, The charged particle detector according to claim 1 , wherein the protective portion is a resistive film covering the outer circumferential conductor.

5. 3. The charged particle detector according to claim 1, wherein the low potential is a potential having an absolute value higher than an absolute value of the reference potential and lower than an absolute value of the second voltage.

6. a substrate on which the semiconductor detector, the protection portion, and the conductor portion are mounted; the semiconductor detector is mounted on a main surface of the substrate; The charged particle detector according to claim 1 , wherein the protective portion and the conductor portion are mounted on a back surface opposite to the main surface.

7. a substrate on which the semiconductor detector and the protection unit are mounted; A housing that houses the substrate, The charged particle detector according to claim 1 , wherein the conductor portion is the housing.

8. A charged particle detector according to claim 1 or 2; and a signal processing unit that processes the electrical signal output from the charged particle detector.

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