WO2015125603A1 - Detector and electron detection device - Google Patents

Detector and electron detection device Download PDF

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Publication number
WO2015125603A1
WO2015125603A1 PCT/JP2015/053061 JP2015053061W WO2015125603A1 WO 2015125603 A1 WO2015125603 A1 WO 2015125603A1 JP 2015053061 W JP2015053061 W JP 2015053061W WO 2015125603 A1 WO2015125603 A1 WO 2015125603A1
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WO
WIPO (PCT)
Prior art keywords
ray
transmission window
detector
sample
electron
Prior art date
Application number
PCT/JP2015/053061
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French (fr)
Japanese (ja)
Inventor
聡史 大橋
Original Assignee
株式会社堀場製作所
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Application filed by 株式会社堀場製作所 filed Critical 株式会社堀場製作所
Priority to JP2016504020A priority Critical patent/JP6416199B2/en
Priority to DE112015000849.7T priority patent/DE112015000849T5/en
Publication of WO2015125603A1 publication Critical patent/WO2015125603A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/1603—Measuring radiation intensity with a combination of at least two different types of detector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/244—Detectors; Associated components or circuits therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2441—Semiconductor detectors, e.g. diodes
    • H01J2237/24415—X-ray
    • H01J2237/2442—Energy-dispersive (Si-Li type) spectrometer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2448—Secondary particle detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/245—Detection characterised by the variable being measured
    • H01J2237/24571—Measurements of non-electric or non-magnetic variables
    • H01J2237/24585—Other variables, e.g. energy, mass, velocity, time, temperature

Definitions

  • the present invention relates to a detector and an electron detection device for detecting electrons together with X-rays generated from a sample irradiated with an electron beam.
  • Some electron microscopes detect secondary electrons and reflected electrons generated from a sample irradiated with an electron beam, and detect X-rays generated from the sample. By detecting X-rays with an electron microscope, observation of an electron image of the sample and elemental analysis of the sample can be performed in parallel. However, in such an electron microscope, it is necessary to provide an electron detector and an X-ray detector, and it is difficult to arrange the detector.
  • Patent Document 1 discloses an apparatus in which an X-ray detector also serves as a backscattered electron detector.
  • the amount of electron-hole pairs generated in the detector by the incidence of X-rays and electrons is measured, and a spectrum is generated. Based on the difference between the spectrum shape of X-rays and the spectrum shape of reflected electrons, the spectrum of X-rays and the spectrum of reflected electrons are separated and detection is performed.
  • An apparatus that also serves as a backscattered electron detector with an X-ray detector has the following problems. If a sufficient amount of X-rays and reflected electrons are not incident on the detector, a spectrum cannot be formed and X-rays and reflected electrons cannot be separated. For this reason, compared with the case where the detector only for a reflected electron is used, time required in order to produce
  • the ratio of X-rays and reflected electrons is changed by changing the acceleration voltage in the electron microscope, it is necessary to replace the X-ray transmission window in accordance with the acceleration voltage.
  • a dead time during which detection cannot be performed even when radiation is incident occurs before and after detection.
  • the frequency of detection increases, and even if X-rays or reflected electrons are incident, there is a high probability that they cannot be detected due to dead time. For this reason, compared with the case where a detector dedicated to X-rays or reflected electrons is used, the resolution of the spectrum is deteriorated, the detection efficiency is deteriorated, and the lifetime of the detector is shortened.
  • This invention is made
  • the place made into the objective is to provide the detector and electron detection apparatus which can detect an X-ray and an electron separately. .
  • the detector according to the present invention is a detector comprising an X-ray transmission window that transmits X-rays and an X-ray detection element that detects X-rays transmitted through the X-ray transmission window.
  • the detector according to the present invention further includes a conductive window frame that supports the X-ray transmission window.
  • the electron detection apparatus is electrically connected to the detector according to the present invention and the X-ray detection element included in the detector, and generates an X-ray spectrum detected by the X-ray detection element.
  • the X-ray transmission window is electrically connected to an outer surface of an X-ray transmission window included in the spectrum generator and the detector, and based on a current generated due to electrons colliding with the X-ray transmission window.
  • a measuring unit that measures the amount of electrons that collided with.
  • An electron detection apparatus is connected to a scanning unit that scans a sample with an electron beam, a detector according to the present invention, and an X-ray detection element included in the detector, and is generated from the sample by the electron beam.
  • a spectrum generation unit that generates an X-ray spectrum detected by the X-ray detection element and an X-ray transmission window included in the detector, and is generated from a sample by an electron beam and is transmitted to the X-ray transmission window.
  • a measuring unit that measures the amount of electrons generated from the sample based on a current generated due to the colliding electrons, and an electron of the sample scanned by the scanning unit based on the amount of electrons measured by the measuring unit
  • an electronic image generation unit that generates an image.
  • the electron detection apparatus further includes a voltage application unit that applies a bias voltage that makes the X-ray transmission window positive with respect to the sample between the sample and the X-ray transmission window. .
  • the electron detection apparatus further includes a calculation unit that calculates a difference in the amount of electrons measured by the measurement unit between when the voltage application unit applies the bias voltage and when the voltage application unit does not apply the bias voltage.
  • the thickness of the X-ray transmission window is such that electrons generated from the sample by the electron beam pass through the X-ray transmission window according to the energy of the electron beam irradiated to the sample by the scanning unit.
  • the transmission probability is determined to be a predetermined value or less.
  • the detector has a through hole, and the electron beam irradiated to the sample by the scanning unit is disposed at a position passing through the through hole. .
  • the detector includes an X-ray transmission window and an X-ray detection element, and the outer surface of the X-ray transmission window has conductivity.
  • X-rays generated from the sample irradiated with the electron beam pass through the X-ray transmission window and are detected by the X-ray detection element.
  • Electrons such as reflected electrons generated from the sample irradiated with the electron beam collide with the X-ray transmission window, and the absorbed electrons generated by the electron collision become a current.
  • An electron detection device including a detector generates an X-ray spectrum and measures the amount of electrons based on a current caused by electrons colliding with the X-ray transmission window.
  • the window frame that supports the X-ray transmission window has conductivity.
  • the electron detector measures the amount of electrons including electrons colliding with the window frame.
  • the X-ray detector applies a bias voltage that makes the X-ray transmission window positive to the sample, and measures the amount of electrons. Electrons are accelerated by the bias voltage, and the electrons are efficiently measured.
  • the X-ray detection device measures the amount of electrons between a state where a bias voltage is applied between the sample and the X-ray transmission window and a state where no bias voltage is applied, and calculates a difference in the amount of electrons.
  • the amount of electrons measured without a bias voltage is the amount of reflected electrons generated from the sample.
  • reflected electrons and secondary electrons generated from the sample collide with the X-ray transmission window.
  • the X-ray detector measures the amount of secondary electrons by calculating the difference in the amount of electrons.
  • the thickness of the X-ray transmission window is determined such that the probability that electrons generated from the sample by the electron beam pass through the X-ray transmission window is equal to or less than a predetermined value. X-rays and electrons are separated and detected individually.
  • the electron detection device is provided with a through hole for allowing an electron beam for irradiating the sample to pass through the X-ray detector.
  • the electron detection device detects X-rays transmitted through the X-ray transmission window, and measures the amount of electrons based on the current generated when the electrons collide with the X-ray transmission window. It is possible to individually detect X-rays and electrons generated from the sample. Therefore, the present invention has an excellent effect, such as no problem with the conventional apparatus that also serves as an electron detector in the X-ray detector.
  • FIG. 1 is a block diagram illustrating a configuration of an electron microscope according to a first embodiment. It is a block diagram which shows the internal structure of a control part.
  • FIG. 6 is a block diagram illustrating a configuration of an electron microscope according to a second embodiment.
  • FIG. 1 is a block diagram illustrating a configuration of an electron microscope according to the first embodiment.
  • the electron microscope is a SEM (scanning electron microscope) and corresponds to the electron detection device of the present invention.
  • the electron microscope includes an electron gun 41 that irradiates the sample 5 with an electron beam, an electron lens system 42, and a sample stage 43 on which the sample 5 is placed.
  • the electron lens system 42 includes a scanning coil that changes the direction of the electron beam.
  • the electron gun 41 and the electron lens system 42 are connected to a control unit 3 that controls the entire X-ray analyzer.
  • an X-ray detector (detector) 1 is disposed between the electron lens system 42 and the sample stage 43.
  • the X-ray detector 1 is formed in a shape provided with a through hole 14 for passing an electron beam.
  • FIG. 1 shows a cross section of the X-ray detector 1.
  • the X-ray detector 1 includes a plurality of X-ray detection elements 11 such as SDD (SiliconSDrift Detector).
  • the X-ray detector 1 has a configuration in which a plurality of X-ray detection elements 11 are arranged so as to surround the through hole 14.
  • the X-ray detector 1 includes an X-ray transmission window 12, and the X-ray transmission window 12 is disposed at a position covering the front surface of the X-ray detection element 11.
  • the through-hole 14 is also formed in the X-ray transmission window 12, and the shape of the X-ray transmission window 12 is annular.
  • the X-ray detector 1 includes a window frame 13 that supports an X-ray transmission window 12.
  • the window frame 13 is provided at the periphery of the X-ray transmission window 12 and the edge of the through hole 14 formed in the X-ray transmission window 12.
  • the X-ray detector 1 includes a cooling mechanism (not shown) such as a Peltier element.
  • the X-ray detector 1 is sealed by an X-ray transmission window 12.
  • the X-ray detector 1 is decompressed or filled with a predetermined gas.
  • the X-ray detector 1 is arranged at a position where the electron beam passes through the through hole 14, the X-ray transmission window 12 intersects the axis of the electron beam, and the X-ray transmission window 12 faces the sample stage 43. ing. In a state where the sample 5 is placed on the sample stage 43, the X-ray detector 1 is disposed in front of the surface of the sample 5 irradiated with the electron beam, and the X-ray transmission window 12 faces the sample 5.
  • the outer surface facing the outside of the X-ray detector 1 faces the sample stage 43.
  • the outer surface of the X-ray transmission window 12 faces the sample 5.
  • At least the outer surface of the X-ray transmission window 12 has conductivity.
  • the X-ray transmission window 12 is made of a conductive material such as beryllium foil.
  • the X-ray transmission window 12 is formed of an insulating material such as a polymer, and a conductor layer is provided on the outer surface of the conductive material.
  • the conductive material used for the X-ray transmission window 12 is preferably a light element such as beryllium, carbon, aluminum, or silicon.
  • the window frame 13 is made of a conductive material.
  • the outer surface of the X-ray transmissive window 12 and the window frame 13 are in electrical contact with each other and can be electrically connected to each other.
  • the outer surface of the X-ray transmission window 12 and the window frame 13 and the X-ray detection element 11 are electrically insulated.
  • the X-ray detection element 11 is disposed in the casing of the X-ray detector 1, and the casing is made of an insulating material, or is insulated between the casing and the X-ray transmission window 12 and the window frame 13. Material is provided.
  • the X-ray detection element 11 is electrically connected to the X-ray detection preamplifier 21.
  • the X-ray detection preamplifier 21 is connected to a pulse shaper 22, and the pulse shaper 22 is connected to the control unit 3.
  • the outer surface of the X-ray transmission window 12 and the window frame 13 are electrically connected to the electron detection preamplifier 23 through a conductive wire.
  • a conductive wire connected to the electron detection preamplifier 23 is connected to the window frame 13 in contact with the outer surface of the X-ray transmission window 12.
  • the electron detection preamplifier 23 is connected to the control unit 3.
  • the electron microscope further includes a voltage application unit 24 that applies a bias voltage between the X-ray transmission window 12 and the window frame 13 and the sample 5.
  • the sample stage 4 is grounded, and the voltage application unit 24 applies a positive bias voltage to the X-ray transmission window 12 and the window frame 13 with respect to the ground potential. As a result, a positive bias voltage is applied to the X-ray transmission window 12 and the window frame 13 with respect to the sample 5.
  • the bias voltage is several tens to several hundreds volts.
  • the voltage application unit 24 switches the application of the bias voltage on and off under the control of the control unit 3.
  • at least the electron gun 41, the electron lens system 42, the X-ray detector 1 and the sample stage 43 are housed in a vacuum box (not shown).
  • the vacuum box is made of a material that shields electron beams and X-rays, and the inside of the vacuum box is kept in a vacuum during the operation of the X-ray analyzer.
  • FIG. 2 is a block diagram showing an internal configuration of the control unit 3.
  • the control unit 3 is configured using a computer such as a personal computer.
  • the control unit 3 includes a CPU (Central Processing Unit) 31 that performs computation, a RAM (Random Access Memory) 32 that stores temporary data generated by the computation, and a drive that reads information from a recording medium 6 such as an optical disk.
  • Unit 33 and a non-volatile storage unit 34 such as a hard disk.
  • the control unit 3 includes an operation unit 35 such as a keyboard or a mouse that accepts a user operation, a display unit 36 such as a liquid crystal display, and an interface unit 37.
  • An electron gun 41, an electron lens system 42, a voltage application unit 24, a pulse shaper 22, and an electron detection preamplifier 23 are connected to the interface unit 37.
  • the CPU 31 causes the drive unit 33 to read the computer program 61 recorded on the recording medium 6 and stores the read computer program 61 in the storage unit 34.
  • the computer program 61 is loaded from the storage unit 34 to the RAM 32 as necessary, and the CPU 31 executes necessary processing according to the loaded computer program 61.
  • the computer program 61 may be downloaded from outside the control unit 3.
  • the control unit 3 controls the operations of the electron gun 41, the electron lens system 42, and the voltage application unit 24 connected to the interface unit 37.
  • the electron gun 41 emits an electron beam
  • the electron lens system 42 determines the direction of the electron beam
  • the electron beam passes through the through hole 14 of the X-ray detector 1 and the sample table 43.
  • the upper sample 5 is irradiated.
  • X-rays are generated, and further, reflected electrons and secondary electrons are generated.
  • X-rays pass through the X-ray transmission window 12 and enter the X-ray detector 1, and are detected by the X-ray detection element 11.
  • the reflected electrons collide with the X-ray transmission window 12 and the window frame 13.
  • the secondary electrons have lower energy than the reflected electrons, and do not reach the X-ray transmission window 12 and the window frame 13 when the voltage application unit 24 does not apply a bias voltage.
  • the secondary electrons collide with the X-ray transmission window 12 and the window frame 13.
  • a path of electrons including an electron beam is indicated by a solid line arrow, and an X-ray is indicated by a broken line arrow.
  • the thickness of the X-ray transmission window 12 is such that X-rays are transmitted as much as possible and reflected electrons are not transmitted.
  • the energy of the electron beam is determined by the acceleration voltage used in the electron gun 41 and the electron lens system 42.
  • the thickness of the X-ray transmission window 12 is set in advance so that the probability that the reflected electrons are transmitted through the X-ray transmission window 12 is not more than a predetermined value such as 0.1% in accordance with the energy of the electron beam used. It has been established.
  • the thickness is 0.5 ⁇ m, and the energy of the electron beam is 5 keV, the reflected electrons hardly pass through the X-ray transmission window 12.
  • the probability that the reflected electrons are transmitted through the X-ray transmission window 12 when the electron beam is irradiated with the maximum energy is less than a predetermined value. What is necessary is just to set thickness.
  • the X-ray detection element 11 outputs a signal proportional to the detected X-ray energy to the X-ray detection preamplifier 21.
  • the X-ray detection preamplifier 21 amplifies and converts the signal from the X-ray detection element 11 and outputs the amplified signal to the pulse shaper 22.
  • the pulse shaper 22 calculates the X-ray energy detected by the X-ray detection element 11 based on the signal from the X-ray detection element 11, and outputs a signal indicating the calculated energy to the control unit 3.
  • the reflected electrons collide with the X-ray transmission window 12 and the window frame 13
  • the reflected electrons lose energy in the scattering process, and absorbed electrons absorbed by the X-ray transmission window 12 and the window frame 13 are generated.
  • the outer surface of the X-ray transmission window 12 and the window frame 13 are conductive, absorbed electrons generated in the X-ray transmission window 12 and the window frame 13 move through the X-ray transmission window 12 and the window frame 13.
  • a current is generated by the movement of the absorbed electrons.
  • the generated current flows through the conductive wires connected to the X-ray transmission window 12 and the window frame 13 and is input to the electron detection preamplifier 23.
  • the absorbed electrons flow out from the X-ray detector 1 as a current.
  • the electron detection preamplifier 23 converts the input current into a voltage signal, amplifies the voltage signal, and outputs the voltage signal to the control unit 3. Further, when the voltage application unit 24 applies a bias voltage to the X-ray transmission window 12 and the window frame 13, the reflected electrons and secondary electrons collide with the X-ray transmission window 12 and the window frame 13. The absorbed electrons generated by the collision of the reflected electrons and the secondary electrons are input to the electron detection preamplifier 23 as a current. Similarly, the electron detection preamplifier 23 outputs a voltage signal caused by the reflected electrons and the secondary electrons to the control unit 3.
  • the control unit 3 receives a signal indicating the X-ray energy output from the pulse shaper 22 by the interface unit 37, counts the signal for each energy, and generates an X-ray spectrum in which the X-ray energy is associated with the count number. Generate.
  • the X-ray detection preamplifier 21, the pulse shaper 22, and the control unit 3 correspond to a spectrum generation unit.
  • the control unit 3 receives the voltage signal output from the electron detection preamplifier 23 by the interface unit 37 and performs a process of calculating the amount of electrons from the voltage signal.
  • the voltage signal output from the electron detection preamplifier 23 corresponds to the amount of absorbed electrons generated in the X-ray transmission window 12 and the window frame 13, and further, the electrons colliding with the X-ray transmission window 12 and the window frame 13. Corresponds to the amount of.
  • the CPU 31 calculates the amount of electrons from the value of the voltage signal.
  • the control unit 3 turns off the application of the bias voltage to the voltage application unit 24 and calculates the amount of electrons in a state where the bias voltage is not applied, so that the X-ray transmission window 12 and the window frame 13 Measure the amount of backscattered electrons.
  • the electron detection preamplifier 23 and the control unit 3 correspond to a measurement unit.
  • control unit 3 turns on the application of the bias voltage to the voltage application unit 24 and calculates the amount of electrons in a state where the bias voltage is applied, so that the X-ray transmission window 12 and the window frame 13 are applied.
  • the total amount of reflected electrons and secondary electrons that collided is measured.
  • the CPU 31 subtracts the amount of electrons calculated in a state where no bias voltage is applied from the amount of electrons calculated in a state where a bias voltage is applied, so that the X-ray transmission window 12 and the window frame are subtracted.
  • the amount of secondary electrons that collided with 13 is measured. In this way, the electron microscope detects X-rays generated from the sample 5 irradiated with the electron beam, reflected electrons, and secondary electrons.
  • the electron lens system 42 sequentially changes the direction of the electron beam, so that the electron beam scans the sample 5.
  • the control unit 3 controls the operation of the electron lens system 42 and specifies the position of the portion irradiated with the electron beam on the sample 5.
  • X-rays, reflected electrons, and secondary electrons generated from the portion irradiated with the electron beam on the sample 5 are sequentially detected.
  • the control unit 3 sequentially generates X-ray spectra generated in a plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 detects the position of the portion irradiated with the electron beam on the sample 5 and the X-rays.
  • An X-ray spectrum distribution is generated in association with the spectrum.
  • control unit 3 sequentially measures the amount of reflected electrons generated in a plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 reflects the position and reflection of the portion irradiated with the electron beam on the sample 5.
  • a backscattered electron image is generated in association with the amount of electrons.
  • the reflected electron image is a distribution of the amount of reflected electrons generated on the sample 5.
  • control unit 3 sequentially measures the amount of secondary electrons generated in the plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 determines the position of the portion irradiated with the electron beam on the sample 5.
  • a secondary electron image is generated by associating the secondary electron quantity with the amount of secondary electrons.
  • the CPU 31 stores data representing the X-ray spectrum distribution, data representing the reflected electron image, and data representing the secondary electron image in the storage unit 34.
  • the control unit 3 can display an image representing the X-ray spectrum distribution, an image representing the reflected electron image, and an image representing the secondary electron image on the display unit 36. .
  • the control unit 3 receives an operation from the user through the operation unit 35, and displays an image desired by the user according to the received operation. Further, the control unit 3 may specify the type and amount of the element contained in the sample 5 from the X-ray spectrum and perform a process of generating an element distribution on the sample 5.
  • the control unit 3 displays an image representing the element distribution on the sample 5 on the display unit 36.
  • the outer surface of the X-ray transmission window 12 and the window frame 13 provided in the X-ray detector 1 are made conductive, and the X-ray transmission window 12 and the X-ray detection element are provided. 11 is electrically insulated. X-rays and reflected electrons are generated from the sample 5 by the electron beam irradiation. X-rays pass through the X-ray transmission window 12 and are detected by the X-ray detection element 11 in the X-ray detector 1. The reflected electrons collide with the X-ray transmission window 12 and the window frame 13, the absorbed electrons flow as current, and the amount of reflected electrons is detected.
  • the electron microscope according to the present embodiment can individually detect X-rays and reflected electrons without providing a reflected electron detector separately from the X-ray detector 1. Since X-rays and backscattered electrons are detected separately, there is no problem with the conventional apparatus that also functions as a backscattered electron detector with an X-ray detector. For example, since it is not necessary to separate the spectrum of X-rays and the spectrum of reflected electrons, it is not necessary to detect a sufficient amount of reflected electrons so that the spectrum can be separated. For this reason, the minimum amount of reflected electrons required for detection is suppressed, and the length of time required to generate a reflected electron image is prevented.
  • the thickness of the X-ray transmission window in order to adjust the S / N ratio or the ratio of X-rays and reflected electrons so that the spectra can be separated.
  • the X-ray detection element 11 detects only X-rays and does not detect reflected electrons, the dead time is shorter than when detecting X-rays and reflected electrons with the same detector. For this reason, deterioration in spectral resolution, deterioration in detection efficiency, and shortening of the lifetime of the detector are prevented.
  • the thickness of the X-ray transmission window 12 is determined such that the probability that the reflected electrons are transmitted is less than or equal to a predetermined value. Are separated and reliably detected individually.
  • the electron microscope measures the amount of electrons when a positive bias voltage is applied to the X-ray transmission window 12 and the window frame 13 and when it is not applied, and the measured amount of electrons is measured. The amount of secondary electrons is measured by calculating the difference. As a result, the electron microscope can individually detect secondary electrons. It is not necessary to separately provide a secondary electron detector, and the arrangement of each part of the electron microscope is facilitated.
  • the X-ray detector 1 is formed with a through hole 14 for allowing an electron beam to pass therethrough.
  • the X-ray detector 1 can be arranged between the electron lens system 42 and the sample stage 43 so that the X-ray detector 1 can be as close to the sample 5 as possible. Become. The X-rays and electrons generated from the sample 5 both increase in intensity as the detection position is closer to the sample 5. By bringing the X-ray detector 1 capable of detecting X-rays and electrons at the same position as close to the sample as possible, the detection efficiency of X-rays, reflected electrons, and secondary electrons is improved.
  • the X-ray detector 1 includes a plurality of X-ray detection elements 11. However, the X-ray detector 1 includes a single X-ray detection element 11. There may be. In the present embodiment, the X-ray transmission window 12 is integrated. However, the X-ray detector 1 may have a plurality of X-ray transmission windows 12.
  • FIG. 3 is a block diagram showing the configuration of the electron microscope according to the second embodiment.
  • the electron microscope according to the present embodiment includes a plurality of X-ray detectors 1. In the drawing, a cross section of the X-ray detector 1 is shown. The X-ray detector 1 is disposed at a position deviated from the position between the electron lens system 42 and the sample stage 43. As in the first embodiment, the X-ray detector 1 includes an X-ray detection element 11, an X-ray transmission window 12, and a window frame 13, and at least the outer surface of the X-ray transmission window 12 and the window frame 13. And have conductivity. The X-ray transmission window 12 and the window frame 13 are electrically insulated from the X-ray detection element 11.
  • the through-hole 14 is not formed in the X-ray detector 1.
  • Each of the plurality of X-ray detectors 1 is arranged with the X-ray transmission window 12 facing the sample stage 43.
  • the electron microscope includes an X-ray detection preamplifier 21, a pulse shaper 22, an electron detection preamplifier 23, a voltage application unit 24, and a control unit 3, which are omitted in FIG. Yes.
  • the X-ray detection element 11 provided in each X-ray detector 1 is electrically connected to the X-ray detection preamplifier 21, and the outer surface of the X-ray transmission window 12 and the window frame 13 are electrically connected to the electron detection preamplifier 23. It is connected to the.
  • the electron gun 41 irradiates the sample 5 on the sample stage 43 with an electron beam.
  • X-rays generated from the sample 5 pass through the X-ray transmission window 12 of each X-ray detector 1 and are detected by the X-ray detector 1.
  • the voltage application unit 24 applies a positive bias voltage to each of the X-ray transmission window 12 and the window frame 13, and the reflected electrons and secondary electrons generated from the sample 5 due to the irradiation of the electron beam are applied to each X-ray detector 1. It collides with the X-ray transmission window 12.
  • the voltage application unit 24 does not apply a positive bias voltage to the X-ray transmission window 12 and the window frame 13 the reflected electrons generated from the sample 5 by the irradiation of the electron beam are detected by each X-ray detector. 1 X-ray transmission window 12 collides. In FIG. 3, electron paths are indicated by solid arrows, and X-rays are indicated by broken arrows.
  • the X-ray detection preamplifier 21, the pulse shaper 22, the electron detection preamplifier 23, the voltage application unit 24, and the control unit 3 execute the same processing as in the first embodiment, and the control unit 3 performs the distribution and reflection of the X-ray spectrum. An electronic image and a secondary electron image are generated, and data representing each is stored in the storage unit 34.
  • the electron microscope can separately detect X-rays, reflected electrons, and secondary electrons without providing a reflected electron detector separately from the X-ray detector 1. Therefore, in the present embodiment, as in the first embodiment, it is possible to prevent an increase in the time required for generating a backscattered electron image, a deterioration in spectral resolution, a deterioration in detection efficiency, and a short detector. Life expectancy is prevented.
  • a form in which a plurality of X-ray detectors 1 having the same shape are arranged at symmetrical positions is shown.
  • the electron microscope is not limited to this, and a plurality of X-rays having different shapes are used.
  • the form provided with the detector 1 may be sufficient, and the form which has arrange
  • the plurality of X-ray detectors 1 may be arranged at positions where the distance from the sample stage 43 is different.
  • the electron microscope may have a form in which the single X-ray detector 1 is disposed at a position deviated from the position between the electron lens system 42 and the sample stage 43.
  • the window frame 13 has a conductivity.
  • the electron microscope is not limited to this, and the window frame 13 has a conductivity. It may be in a form that is not.
  • an electron detection preamplifier 23 is electrically connected to the outer surface of the X-ray transmission window 12, and the electron microscope measures the amount of electrons that have collided with the X-ray transmission window 12.
  • the positive bias voltage is applied to the X-ray transmission window 12 with respect to the sample 5, but the electron microscope has a negative bias with respect to the X-ray transmission window 12. The voltage may be applied to the sample 5.
  • the electron microscope is not restricted to this, The voltage application part 24 is not provided. Alternatively, the secondary electron detection using the X-ray detector 1 may not be performed. In this embodiment, the electron microscope includes a secondary electron detector separately from the X-ray detector 1.
  • the X-ray detection element 11 is an SDD, but the X-ray detection element 11 may be a detection element other than the SDD.
  • the electron detection device of the present invention is an SEM. However, the present invention is not limited to this, and the electron detection device of the present invention may be another device.
  • the electron detection device may have a form in which the X-ray detector 1 is incorporated in a TEM (transmission electron microscope) or a microanalyzer. Further, the electron detector itself may not have a function of irradiating the sample 5 with an electron beam.

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Abstract

Provided are a detector capable of detecting X-rays and electrons separately, and an electron detection device. The X-ray detector (detector) (1) is provided with an X-ray detection element (11) and an X-ray-transmitting window (12). The X-ray-transmitting window (12) has an electrically conductive external surface and is electrically insulated from the X-ray detection element (11). An X-ray generated from a sample (5) that is irradiated by an electron beam passes through the X-ray-transmitting window (12) and is detected by the X-ray detection element (11). Electrons, such as reflected electrons generated from the sample (5) that is irradiated by the electron beam, collide with the X-ray-transmitting window (12), generating a current. An X-ray detection preamplifier (21) converts the generated current into a voltage signal. Based on the voltage signal, a control unit (3) measures the amount of electrons that have collided with the X-ray-transmitting window (12). In this manner, X-ray and electrons are detected separately.

Description

検出器及び電子検出装置Detector and electronic detection device
　本発明は、電子線を照射された試料から発生するＸ線と共に電子を検出するための検出器、及び電子検出装置に関する。 The present invention relates to a detector and an electron detection device for detecting electrons together with X-rays generated from a sample irradiated with an electron beam.
　電子顕微鏡には、電子線を照射された試料から発生する二次電子及び反射電子を検出すると共に、試料から発生するＸ線を検出するものがある。電子顕微鏡でＸ線を検出することにより、試料の電子像の観察と試料の元素分析とを並行して行うことができる。但し、このような電子顕微鏡では、電子検出器とＸ線検出器とを備える必要があり、検出器の配置が困難である。 Some electron microscopes detect secondary electrons and reflected electrons generated from a sample irradiated with an electron beam, and detect X-rays generated from the sample. By detecting X-rays with an electron microscope, observation of an electron image of the sample and elemental analysis of the sample can be performed in parallel. However, in such an electron microscope, it is necessary to provide an electron detector and an X-ray detector, and it is difficult to arrange the detector.
　特許文献１には、Ｘ線検出器が反射電子検出器を兼ねている装置が開示されている。この装置では、Ｘ線及び電子が入射することによって検出器内に発生する電子・正孔対の量を測定し、スペクトルを生成する。Ｘ線のスペクトル形状と反射電子のスペクトル形状との違いに基づいて、Ｘ線のスペクトルと反射電子のスペクトルとを分離し、夫々の検出を行っている。 Patent Document 1 discloses an apparatus in which an X-ray detector also serves as a backscattered electron detector. In this apparatus, the amount of electron-hole pairs generated in the detector by the incidence of X-rays and electrons is measured, and a spectrum is generated. Based on the difference between the spectrum shape of X-rays and the spectrum shape of reflected electrons, the spectrum of X-rays and the spectrum of reflected electrons are separated and detection is performed.
国際公開第２０１０／１１５８７３号International Publication No. 2010/115873
　Ｘ線検出器で反射電子検出器を兼ねた装置では、次のような問題がある。十分な量のＸ線及び反射電子が検出器に入射しなければ、スペクトルが形成できず、Ｘ線と反射電子との分離ができない。このため、反射電子専用の検出器を用いる場合に比べて、反射電子の像を生成するために必要な時間が長大化する。また、検出されるＸ線と反射電子との比率は、検出器に設けられたＸ線透過窓の厚みで調整される。Ｘ線透過窓の厚みが適切でない場合は、一方のスペクトルに他方のスペクトルが埋没してＳ／Ｎ比が悪化し、スペクトルの分離ができないこともある。また、電子顕微鏡での加速電圧を変更することによってＸ線と反射電子との比率が変わるので、加速電圧に応じてＸ線透過窓を交換する必要があった。また、放射線の検出器では、検出前後に、放射線が入射しても検出を行うことができない不感時間が発生する。Ｘ線と反射電子とを同一の検出器で検出する場合には、検出の頻度が増加し、Ｘ線又は反射電子が入射しても不感時間のために検出ができない確率が高くなる。このため、Ｘ線又は反射電子の専用の検出器を用いた場合に比べて、スペクトルの分解能の悪化、検出効率の悪化、及び検出器の短寿命化を招く。 An apparatus that also serves as a backscattered electron detector with an X-ray detector has the following problems. If a sufficient amount of X-rays and reflected electrons are not incident on the detector, a spectrum cannot be formed and X-rays and reflected electrons cannot be separated. For this reason, compared with the case where the detector only for a reflected electron is used, time required in order to produce | generate an image of a reflected electron becomes long. Further, the ratio of detected X-rays to reflected electrons is adjusted by the thickness of the X-ray transmission window provided in the detector. When the thickness of the X-ray transmission window is not appropriate, the other spectrum is buried in one spectrum, the S / N ratio is deteriorated, and the spectrum may not be separated. Further, since the ratio of X-rays and reflected electrons is changed by changing the acceleration voltage in the electron microscope, it is necessary to replace the X-ray transmission window in accordance with the acceleration voltage. In addition, in the radiation detector, a dead time during which detection cannot be performed even when radiation is incident occurs before and after detection. When X-rays and reflected electrons are detected by the same detector, the frequency of detection increases, and even if X-rays or reflected electrons are incident, there is a high probability that they cannot be detected due to dead time. For this reason, compared with the case where a detector dedicated to X-rays or reflected electrons is used, the resolution of the spectrum is deteriorated, the detection efficiency is deteriorated, and the lifetime of the detector is shortened.
　本発明は、斯かる事情に鑑みてなされたものであって、その目的とするところは、Ｘ線と電子とを個別に検出することができる検出器、及び電子検出装置を提供することにある。 This invention is made | formed in view of such a situation, The place made into the objective is to provide the detector and electron detection apparatus which can detect an X-ray and an electron separately. .
　本発明に係る検出器は、Ｘ線を透過させるＸ線透過窓と、該Ｘ線透過窓を透過したＸ線を検出するＸ線検出素子とを備える検出器において、前記Ｘ線透過窓の外面は導電性を有しており、前記Ｘ線透過窓は、外面に電子が衝突することによって発生した吸収電子が電流として流出するように構成してあることを特徴とする。 The detector according to the present invention is a detector comprising an X-ray transmission window that transmits X-rays and an X-ray detection element that detects X-rays transmitted through the X-ray transmission window. Has an electrical conductivity, and the X-ray transmission window is configured such that absorbed electrons generated when electrons collide with the outer surface flow out as current.
　本発明に係る検出器は、前記Ｘ線透過窓を支持する導電性の窓枠を更に備えることを特徴とする。 The detector according to the present invention further includes a conductive window frame that supports the X-ray transmission window.
　本発明に係る電子検出装置は、本発明に係る検出器と、該検出器が有するＸ線検出素子に電気的に接続されており、該Ｘ線検出素子が検出したＸ線のスペクトルを生成するスペクトル生成部と、前記検出器が有するＸ線透過窓の外面に電気的に接続されており、該Ｘ線透過窓に衝突した電子に起因して発生する電流に基づいて、前記Ｘ線透過窓に衝突した電子の量を計測する計測部とを備えることを特徴とする。 The electron detection apparatus according to the present invention is electrically connected to the detector according to the present invention and the X-ray detection element included in the detector, and generates an X-ray spectrum detected by the X-ray detection element. The X-ray transmission window is electrically connected to an outer surface of an X-ray transmission window included in the spectrum generator and the detector, and based on a current generated due to electrons colliding with the X-ray transmission window. And a measuring unit that measures the amount of electrons that collided with.
　本発明に係る電子検出装置は、試料を電子線で走査する走査部と、本発明に係る検出器と、該検出器が有するＸ線検出素子に接続されており、電子線によって試料から発生して前記Ｘ線検出素子が検出したＸ線のスペクトルを生成するスペクトル生成部と、前記検出器が有するＸ線透過窓に接続されており、電子線によって試料から発生して前記Ｘ線透過窓に衝突した電子に起因して発生する電流に基づいて、試料から発生した電子の量を計測する計測部と、該計測部が計測した電子の量に基づいて、前記走査部が走査した試料の電子像を生成する電子像生成部とを備えることを特徴とする。 An electron detection apparatus according to the present invention is connected to a scanning unit that scans a sample with an electron beam, a detector according to the present invention, and an X-ray detection element included in the detector, and is generated from the sample by the electron beam. Connected to a spectrum generation unit that generates an X-ray spectrum detected by the X-ray detection element and an X-ray transmission window included in the detector, and is generated from a sample by an electron beam and is transmitted to the X-ray transmission window. A measuring unit that measures the amount of electrons generated from the sample based on a current generated due to the colliding electrons, and an electron of the sample scanned by the scanning unit based on the amount of electrons measured by the measuring unit And an electronic image generation unit that generates an image.
　本発明に係る電子検出装置は、試料と前記Ｘ線透過窓との間に、試料に対して前記Ｘ線透過窓が正となるバイアス電圧を印加する電圧印加部を更に備えることを特徴とする。 The electron detection apparatus according to the present invention further includes a voltage application unit that applies a bias voltage that makes the X-ray transmission window positive with respect to the sample between the sample and the X-ray transmission window. .
　本発明に係る電子検出装置は、前記電圧印加部が前記バイアス電圧を印加した場合と印加しなかった場合とで前記計測部が計測した電子の量の差を計算する計算部を更に備えることを特徴とする。 The electron detection apparatus according to the present invention further includes a calculation unit that calculates a difference in the amount of electrons measured by the measurement unit between when the voltage application unit applies the bias voltage and when the voltage application unit does not apply the bias voltage. Features.
　本発明に係る電子検出装置は、前記Ｘ線透過窓の厚みは、前記走査部が試料へ照射する電子線のエネルギーに応じて、前記電子線によって試料から発生した電子が前記Ｘ線透過窓を透過する確率が所定値以下になるように定められていることを特徴とする。 In the electron detection device according to the present invention, the thickness of the X-ray transmission window is such that electrons generated from the sample by the electron beam pass through the X-ray transmission window according to the energy of the electron beam irradiated to the sample by the scanning unit. The transmission probability is determined to be a predetermined value or less.
　本発明に係る電子検出装置は、前記検出器は、貫通孔を有しており、前記走査部が試料へ照射する電子線が前記貫通孔を通過する位置に配置されていることを特徴とする。 In the electron detection apparatus according to the present invention, the detector has a through hole, and the electron beam irradiated to the sample by the scanning unit is disposed at a position passing through the through hole. .
　本発明においては、検出器は、Ｘ線透過窓とＸ線検出素子とを備え、Ｘ線透過窓は外面が導電性を有している。電子線を照射された試料から発生したＸ線は、Ｘ線透過窓を透過してＸ線検出素子で検出される。電子線を照射された試料から発生した反射電子等の電子は、Ｘ線透過窓に衝突し、電子の衝突により発生した吸収電子は電流となる。検出器を備える電子検出装置は、Ｘ線のスペクトルを生成し、Ｘ線透過窓に衝突した電子に起因した電流に基づいて、電子の量を計測する。 In the present invention, the detector includes an X-ray transmission window and an X-ray detection element, and the outer surface of the X-ray transmission window has conductivity. X-rays generated from the sample irradiated with the electron beam pass through the X-ray transmission window and are detected by the X-ray detection element. Electrons such as reflected electrons generated from the sample irradiated with the electron beam collide with the X-ray transmission window, and the absorbed electrons generated by the electron collision become a current. An electron detection device including a detector generates an X-ray spectrum and measures the amount of electrons based on a current caused by electrons colliding with the X-ray transmission window.
　本発明においては、Ｘ線透過窓を支持する窓枠が導電性を有している。電子検出器は、窓枠に衝突した電子を含む電子の量を計測する。 In the present invention, the window frame that supports the X-ray transmission window has conductivity. The electron detector measures the amount of electrons including electrons colliding with the window frame.
　本発明においては、Ｘ線検出装置は、試料に対してＸ線透過窓が正となるバイアス電圧を印加し、電子の量を計測する。バイアス電圧によって電子が加速され、効率的に電子が計測される。 In the present invention, the X-ray detector applies a bias voltage that makes the X-ray transmission window positive to the sample, and measures the amount of electrons. Electrons are accelerated by the bias voltage, and the electrons are efficiently measured.
　本発明においては、Ｘ線検出装置は、試料とＸ線透過窓との間にバイアス電圧を印加した状態と印加しない状態とで電子の量を計測し、電子の量の差を計算する。バイアス電圧無しの状態で計測した電子の量は、試料から発生した反射電子の量である。バイアス電圧を印加した状態では、試料から発生した反射電子及び二次電子がＸ線透過窓に衝突する。Ｘ線検出装置は、電子の量の差を計算することにより、二次電子の量を計測する。 In the present invention, the X-ray detection device measures the amount of electrons between a state where a bias voltage is applied between the sample and the X-ray transmission window and a state where no bias voltage is applied, and calculates a difference in the amount of electrons. The amount of electrons measured without a bias voltage is the amount of reflected electrons generated from the sample. In a state where a bias voltage is applied, reflected electrons and secondary electrons generated from the sample collide with the X-ray transmission window. The X-ray detector measures the amount of secondary electrons by calculating the difference in the amount of electrons.
　本発明においては、Ｘ線透過窓の厚みは、電子線によって試料から発生した電子がＸ線透過窓を透過する確率が所定値以下になるように定められている。Ｘ線と電子とが分離され、個別に検出される。 In the present invention, the thickness of the X-ray transmission window is determined such that the probability that electrons generated from the sample by the electron beam pass through the X-ray transmission window is equal to or less than a predetermined value. X-rays and electrons are separated and detected individually.
　本発明においては、電子検出装置は、Ｘ線検出器に、試料へ照射するための電子線を通過させるための貫通孔を設けてある。電子線源と試料との間にＸ線検出器を配置して、Ｘ線検出器を可及的に試料へ近づけることが可能となる。 In the present invention, the electron detection device is provided with a through hole for allowing an electron beam for irradiating the sample to pass through the X-ray detector. By arranging an X-ray detector between the electron beam source and the sample, the X-ray detector can be brought as close to the sample as possible.
　本発明にあっては、電子検出装置は、Ｘ線透過窓を透過したＸ線を検出し、Ｘ線透過窓に電子が衝突して発生した電流に基づいて電子の量を計測することにより、試料から発生したＸ線と電子とを個別に検出することが可能である。従って、Ｘ線検出器で電子の検出器を兼ねた従来の装置での問題が発生しない等、本発明は優れた効果を奏する。 In the present invention, the electron detection device detects X-rays transmitted through the X-ray transmission window, and measures the amount of electrons based on the current generated when the electrons collide with the X-ray transmission window. It is possible to individually detect X-rays and electrons generated from the sample. Therefore, the present invention has an excellent effect, such as no problem with the conventional apparatus that also serves as an electron detector in the X-ray detector.
実施の形態１に係る電子顕微鏡の構成を示すブロック図である。1 is a block diagram illustrating a configuration of an electron microscope according to a first embodiment. 制御部の内部構成を示すブロック図である。It is a block diagram which shows the internal structure of a control part. 実施の形態２に係る電子顕微鏡の構成を示すブロック図である。FIG. 6 is a block diagram illustrating a configuration of an electron microscope according to a second embodiment.
　以下本発明をその実施の形態を示す図面に基づき具体的に説明する。
（実施の形態１）
　図１は、実施の形態１に係る電子顕微鏡の構成を示すブロック図である。電子顕微鏡は、ＳＥＭ（走査型電子顕微鏡）であり、本発明の電子検出装置に対応する。電子顕微鏡は、試料５に電子線を照射する電子銃４１と、電子レンズ系４２と、試料５が載置される試料台４３とを備えている。電子レンズ系４２は、電子線の方向を変更させる走査コイルを含んでいる。電子銃４１及び電子レンズ系４２は、Ｘ線分析装置全体を制御する制御部３に接続されている。 Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of an electron microscope according to the first embodiment. The electron microscope is a SEM (scanning electron microscope) and corresponds to the electron detection device of the present invention. The electron microscope includes an electron gun 41 that irradiates the sample 5 with an electron beam, an electron lens system 42, and a sample stage 43 on which the sample 5 is placed. The electron lens system 42 includes a scanning coil that changes the direction of the electron beam. The electron gun 41 and the electron lens system 42 are connected to a control unit 3 that controls the entire X-ray analyzer.
　電子レンズ系４２と試料台４３との間には、Ｘ線検出器（検出器）１が配置されている。Ｘ線検出器１は、電子線を通すための貫通孔１４を設けた形状に形成されている。図１中には、Ｘ線検出器１の断面を示している。また、Ｘ線検出器１は、ＳＤＤ（Silicon Drift Detector）等の複数のＸ線検出素子１１を含んで構成されている。Ｘ線検出器１は、貫通孔１４を囲んで複数のＸ線検出素子１１が配置された構成となっている。また、Ｘ線検出器１は、Ｘ線透過窓１２を備えており、Ｘ線透過窓１２はＸ線検出素子１１の正面に被さる位置に配置されている。貫通孔１４はＸ線透過窓１２にも形成されており、Ｘ線透過窓１２の形状は環状になっている。Ｘ線検出器１は、Ｘ線透過窓１２を支持する窓枠１３を備えている。窓枠１３は、Ｘ線透過窓１２の周縁と、Ｘ線透過窓１２に形成された貫通孔１４の縁とに設けられている。また、Ｘ線検出器１は、ペルチェ素子等の図示しない冷却機構を備えている。Ｘ線検出器１は、Ｘ線透過窓１２によって封止されている。Ｘ線検出器１内は、減圧されているか、又は所定のガスが封入されている。Ｘ線検出器１は、貫通孔１４を電子線が通る位置に配置され、Ｘ線透過窓１２が電子線の軸に交差し、Ｘ線透過窓１２が試料台４３に対向するように配置されている。試料５が試料台４３に載置された状態では、試料５の電子線が照射される面の前面にＸ線検出器１が配置され、Ｘ線透過窓１２は試料５に対向している。 Between the electron lens system 42 and the sample stage 43, an X-ray detector (detector) 1 is disposed. The X-ray detector 1 is formed in a shape provided with a through hole 14 for passing an electron beam. FIG. 1 shows a cross section of the X-ray detector 1. The X-ray detector 1 includes a plurality of X-ray detection elements 11 such as SDD (SiliconSDrift Detector). The X-ray detector 1 has a configuration in which a plurality of X-ray detection elements 11 are arranged so as to surround the through hole 14. The X-ray detector 1 includes an X-ray transmission window 12, and the X-ray transmission window 12 is disposed at a position covering the front surface of the X-ray detection element 11. The through-hole 14 is also formed in the X-ray transmission window 12, and the shape of the X-ray transmission window 12 is annular. The X-ray detector 1 includes a window frame 13 that supports an X-ray transmission window 12. The window frame 13 is provided at the periphery of the X-ray transmission window 12 and the edge of the through hole 14 formed in the X-ray transmission window 12. The X-ray detector 1 includes a cooling mechanism (not shown) such as a Peltier element. The X-ray detector 1 is sealed by an X-ray transmission window 12. The X-ray detector 1 is decompressed or filled with a predetermined gas. The X-ray detector 1 is arranged at a position where the electron beam passes through the through hole 14, the X-ray transmission window 12 intersects the axis of the electron beam, and the X-ray transmission window 12 faces the sample stage 43. ing. In a state where the sample 5 is placed on the sample stage 43, the X-ray detector 1 is disposed in front of the surface of the sample 5 irradiated with the electron beam, and the X-ray transmission window 12 faces the sample 5.
　Ｘ線透過窓１２の面の内、Ｘ線検出器１外に面した外面は、試料台４３に対向している。試料５が試料台４３に載置された状態では、Ｘ線透過窓１２の外面は試料５に対向している。Ｘ線透過窓１２は、少なくとも外面が導電性を有している。例えば、Ｘ線透過窓１２は、ベリリウム箔等の導電性材で構成されている。また、例えば、Ｘ線透過窓１２は、ポリマー等の絶縁性材で形成されており、外面に導電性材で導体層が設けられている。Ｘ線透過窓１２に用いられる導電性材は、ベリリウム、カーボン、アルミニウム又はシリコン等の軽元素であることが望ましい。導電性材として軽元素を用いた場合は、Ｘ線透過窓１２をＸ線が透過する効率が高く、Ｘ線透過窓１２に衝突した電子が再放出される確率が低い。また、窓枠１３は、導電性材で構成されている。Ｘ線透過窓１２の外面と窓枠１３とは電気的に接触しており、互いに導通可能になっている。一方で、Ｘ線透過窓１２の外面及び窓枠１３とＸ線検出素子１１との間は、電気的に絶縁されている。例えば、Ｘ線検出素子１１はＸ線検出器１のケーシング内に配置されており、ケーシングが絶縁材で構成されているか、又は、ケーシングとＸ線透過窓１２及び窓枠１３との間に絶縁材が設けられている。 Of the surface of the X-ray transmission window 12, the outer surface facing the outside of the X-ray detector 1 faces the sample stage 43. In the state where the sample 5 is placed on the sample stage 43, the outer surface of the X-ray transmission window 12 faces the sample 5. At least the outer surface of the X-ray transmission window 12 has conductivity. For example, the X-ray transmission window 12 is made of a conductive material such as beryllium foil. Further, for example, the X-ray transmission window 12 is formed of an insulating material such as a polymer, and a conductor layer is provided on the outer surface of the conductive material. The conductive material used for the X-ray transmission window 12 is preferably a light element such as beryllium, carbon, aluminum, or silicon. When a light element is used as the conductive material, the efficiency of X-ray transmission through the X-ray transmission window 12 is high, and the probability that electrons colliding with the X-ray transmission window 12 are re-emitted is low. The window frame 13 is made of a conductive material. The outer surface of the X-ray transmissive window 12 and the window frame 13 are in electrical contact with each other and can be electrically connected to each other. On the other hand, the outer surface of the X-ray transmission window 12 and the window frame 13 and the X-ray detection element 11 are electrically insulated. For example, the X-ray detection element 11 is disposed in the casing of the X-ray detector 1, and the casing is made of an insulating material, or is insulated between the casing and the X-ray transmission window 12 and the window frame 13. Material is provided.
　Ｘ線検出素子１１は、Ｘ線検出用プリアンプ２１に電気的に接続されている。Ｘ線検出用プリアンプ２１はパルスシェーパ２２に接続されており、パルスシェーパ２２は制御部３に接続されている。Ｘ線透過窓１２の外面及び窓枠１３は、導線を通じて電子検出用プリアンプ２３に電気的に接続されている。例えば、Ｘ線透過窓１２の外面に接触した窓枠１３に、電子検出用プリアンプ２３につながる導線が接続されている。電子検出用プリアンプ２３は制御部３に接続されている。更に、電子顕微鏡は、Ｘ線透過窓１２及び窓枠１３と試料５との間にバイアス電圧を印加する電圧印加部２４を備えている。試料台４は接地されており、電圧印加部２４は、接地電位に対して正のバイアス電圧をＸ線透過窓１２及び窓枠１３に印加する。これにより、試料５に対して正のバイアス電圧がＸ線透過窓１２及び窓枠１３に印加される。バイアス電圧は数十～数百Ｖである。電圧印加部２４は、制御部３の制御によって、バイアス電圧の印加のオンとオフとを切り替える。電子顕微鏡の構成の内、少なくとも電子銃４１、電子レンズ系４２、Ｘ線検出器１及び試料台４３は、図示しない真空箱の中に納められている。真空箱は、電子線及びＸ線を遮蔽する材料で構成されており、Ｘ線分析装置の動作中には真空箱の内部は真空に保たれている。 The X-ray detection element 11 is electrically connected to the X-ray detection preamplifier 21. The X-ray detection preamplifier 21 is connected to a pulse shaper 22, and the pulse shaper 22 is connected to the control unit 3. The outer surface of the X-ray transmission window 12 and the window frame 13 are electrically connected to the electron detection preamplifier 23 through a conductive wire. For example, a conductive wire connected to the electron detection preamplifier 23 is connected to the window frame 13 in contact with the outer surface of the X-ray transmission window 12. The electron detection preamplifier 23 is connected to the control unit 3. The electron microscope further includes a voltage application unit 24 that applies a bias voltage between the X-ray transmission window 12 and the window frame 13 and the sample 5. The sample stage 4 is grounded, and the voltage application unit 24 applies a positive bias voltage to the X-ray transmission window 12 and the window frame 13 with respect to the ground potential. As a result, a positive bias voltage is applied to the X-ray transmission window 12 and the window frame 13 with respect to the sample 5. The bias voltage is several tens to several hundreds volts. The voltage application unit 24 switches the application of the bias voltage on and off under the control of the control unit 3. Among the configurations of the electron microscope, at least the electron gun 41, the electron lens system 42, the X-ray detector 1 and the sample stage 43 are housed in a vacuum box (not shown). The vacuum box is made of a material that shields electron beams and X-rays, and the inside of the vacuum box is kept in a vacuum during the operation of the X-ray analyzer.
　図２は、制御部３の内部構成を示すブロック図である。制御部３は、パーソナルコンピュータ等のコンピュータを用いて構成されている。制御部３は、演算を行うＣＰＵ（Central Processing Unit ）３１と、演算に伴って発生する一時的なデータを記憶するＲＡＭ（Random Access Memory）３２と、光ディスク等の記録媒体６から情報を読み取るドライブ部３３と、ハードディスク等の不揮発性の記憶部３４とを備えている。また制御部３は、使用者の操作を受け付けるキーボード又はマウス等の操作部３５と、液晶ディスプレイ等の表示部３６と、インタフェース部３７とを備えている。インタフェース部３７には、電子銃４１、電子レンズ系４２、電圧印加部２４、パルスシェーパ２２及び電子検出用プリアンプ２３が接続されている。ＣＰＵ３１は、記録媒体６に記録されたコンピュータプログラム６１をドライブ部３３に読み取らせ、読み取ったコンピュータプログラム６１を記憶部３４に記憶させる。コンピュータプログラム６１は必要に応じて記憶部３４からＲＡＭ３２へロードされ、ＣＰＵ３１は、ロードされたコンピュータプログラム６１に従って必要な処理を実行する。なお、コンピュータプログラム６１は、制御部３の外部からダウンロードされてもよい。また、制御部３は、インタフェース部３７に接続された電子銃４１、電子レンズ系４２及び電圧印加部２４の動作を制御する。 FIG. 2 is a block diagram showing an internal configuration of the control unit 3. The control unit 3 is configured using a computer such as a personal computer. The control unit 3 includes a CPU (Central Processing Unit) 31 that performs computation, a RAM (Random Access Memory) 32 that stores temporary data generated by the computation, and a drive that reads information from a recording medium 6 such as an optical disk. Unit 33 and a non-volatile storage unit 34 such as a hard disk. Further, the control unit 3 includes an operation unit 35 such as a keyboard or a mouse that accepts a user operation, a display unit 36 such as a liquid crystal display, and an interface unit 37. An electron gun 41, an electron lens system 42, a voltage application unit 24, a pulse shaper 22, and an electron detection preamplifier 23 are connected to the interface unit 37. The CPU 31 causes the drive unit 33 to read the computer program 61 recorded on the recording medium 6 and stores the read computer program 61 in the storage unit 34. The computer program 61 is loaded from the storage unit 34 to the RAM 32 as necessary, and the CPU 31 executes necessary processing according to the loaded computer program 61. The computer program 61 may be downloaded from outside the control unit 3. The control unit 3 controls the operations of the electron gun 41, the electron lens system 42, and the voltage application unit 24 connected to the interface unit 37.
　制御部３からの制御信号に従って、電子銃４１が電子線を放出し、電子レンズ系４２が電子線の方向を定め、電子線はＸ線検出器１の貫通孔１４を通過して試料台４３上の試料５へ照射される。試料５上で、電子線を照射された部分では、Ｘ線が発生し、更に、反射電子及び二次電子が発生する。Ｘ線は、Ｘ線透過窓１２を透過してＸ線検出器１内へ入射し、Ｘ線検出素子１１で検出される。反射電子は、Ｘ線透過窓１２及び窓枠１３に衝突する。二次電子は、反射電子よりも低エネルギーであり、電圧印加部２４がバイアス電圧を印加していない状態では、Ｘ線透過窓１２及び窓枠１３へは達しない。電圧印加部２４がバイアス電圧をＸ線透過窓１２及び窓枠１３に印加している状態では、二次電子はＸ線透過窓１２及び窓枠１３に衝突する。図１中には、電子線を含む電子の経路を実線矢印で示し、Ｘ線を破線矢印で示している。 In accordance with a control signal from the control unit 3, the electron gun 41 emits an electron beam, the electron lens system 42 determines the direction of the electron beam, and the electron beam passes through the through hole 14 of the X-ray detector 1 and the sample table 43. The upper sample 5 is irradiated. In the portion irradiated with the electron beam on the sample 5, X-rays are generated, and further, reflected electrons and secondary electrons are generated. X-rays pass through the X-ray transmission window 12 and enter the X-ray detector 1, and are detected by the X-ray detection element 11. The reflected electrons collide with the X-ray transmission window 12 and the window frame 13. The secondary electrons have lower energy than the reflected electrons, and do not reach the X-ray transmission window 12 and the window frame 13 when the voltage application unit 24 does not apply a bias voltage. In a state where the voltage application unit 24 applies a bias voltage to the X-ray transmission window 12 and the window frame 13, the secondary electrons collide with the X-ray transmission window 12 and the window frame 13. In FIG. 1, a path of electrons including an electron beam is indicated by a solid line arrow, and an X-ray is indicated by a broken line arrow.
　Ｘ線透過窓１２の厚みは、可及的にＸ線が透過し反射電子が透過しない大きさになっている。試料へ照射する電子線のエネルギーが大きいほど、反射電子のエネルギーが大きくなり、Ｘ線透過窓１２を透過しやすくなる。電子線のエネルギーは、電子銃４１及び電子レンズ系４２で用いられる加速電圧で決定される。Ｘ線透過窓１２の厚みは、使用される電子線のエネルギーに応じて、反射電子がＸ線透過窓１２を透過する確率が０．１％等の所定値以下となるような大きさに予め定められている。例えば、Ｘ線透過窓１２の材料がベリリウム箔であり、厚みが０．５μｍであり、電子線のエネルギーが５ｋｅＶである場合は、反射電子はほとんどＸ線透過窓１２を透過することは無い。電子線のエネルギーを調整できる電子顕微鏡では、最大のエネルギーで電子線が照射された場合に反射電子がＸ線透過窓１２を透過する確率が所定値以下となるように、Ｘ線透過窓１２の厚みを定めておけばよい。 The thickness of the X-ray transmission window 12 is such that X-rays are transmitted as much as possible and reflected electrons are not transmitted. The greater the energy of the electron beam applied to the sample, the greater the energy of the reflected electrons and the easier it is to transmit through the X-ray transmission window 12. The energy of the electron beam is determined by the acceleration voltage used in the electron gun 41 and the electron lens system 42. The thickness of the X-ray transmission window 12 is set in advance so that the probability that the reflected electrons are transmitted through the X-ray transmission window 12 is not more than a predetermined value such as 0.1% in accordance with the energy of the electron beam used. It has been established. For example, when the material of the X-ray transmission window 12 is beryllium foil, the thickness is 0.5 μm, and the energy of the electron beam is 5 keV, the reflected electrons hardly pass through the X-ray transmission window 12. In the electron microscope capable of adjusting the energy of the electron beam, the probability that the reflected electrons are transmitted through the X-ray transmission window 12 when the electron beam is irradiated with the maximum energy is less than a predetermined value. What is necessary is just to set thickness.
　Ｘ線検出素子１１は、検出したＸ線のエネルギーに比例した信号を、Ｘ線検出用プリアンプ２１へ出力する。Ｘ線検出用プリアンプ２１は、Ｘ線検出素子１１からの信号を増幅・変換し、パルスシェーパ２２へ出力する。パルスシェーパ２２は、Ｘ線検出素子１１からの信号に基づいて、Ｘ線検出素子１１で検出したＸ線のエネルギーを計算し、計算したエネルギーを示す信号を制御部３へ出力する。 The X-ray detection element 11 outputs a signal proportional to the detected X-ray energy to the X-ray detection preamplifier 21. The X-ray detection preamplifier 21 amplifies and converts the signal from the X-ray detection element 11 and outputs the amplified signal to the pulse shaper 22. The pulse shaper 22 calculates the X-ray energy detected by the X-ray detection element 11 based on the signal from the X-ray detection element 11, and outputs a signal indicating the calculated energy to the control unit 3.
　Ｘ線透過窓１２及び窓枠１３に反射電子が衝突することにより、反射電子が散乱過程でエネルギーを失ってＸ線透過窓１２及び窓枠１３に吸収された吸収電子が発生する。Ｘ線透過窓１２の外面及び窓枠１３は導電性を有するので、Ｘ線透過窓１２及び窓枠１３に発生した吸収電子は、Ｘ線透過窓１２及び窓枠１３を通じて移動する。吸収電子が移動することによって、電流が発生する。発生した電流は、Ｘ線透過窓１２及び窓枠１３に接続された導線を通じて流れ、電子検出用プリアンプ２３へ入力される。このように、吸収電子は電流となってＸ線検出器１から流出する。電子検出用プリアンプ２３は、入力された電流を電圧信号へ変換し、電圧信号を増幅し、電圧信号を制御部３へ出力する。また、電圧印加部２４がバイアス電圧をＸ線透過窓１２及び窓枠１３に印加した場合は、反射電子及び二次電子がＸ線透過窓１２及び窓枠１３に衝突する。反射電子及び二次電子の衝突によって発生した吸収電子は、電流となって電子検出用プリアンプ２３へ入力される。電子検出用プリアンプ２３は、同様に、反射電子及び二次電子に起因する電圧信号を制御部３へ出力する。 When the reflected electrons collide with the X-ray transmission window 12 and the window frame 13, the reflected electrons lose energy in the scattering process, and absorbed electrons absorbed by the X-ray transmission window 12 and the window frame 13 are generated. Since the outer surface of the X-ray transmission window 12 and the window frame 13 are conductive, absorbed electrons generated in the X-ray transmission window 12 and the window frame 13 move through the X-ray transmission window 12 and the window frame 13. A current is generated by the movement of the absorbed electrons. The generated current flows through the conductive wires connected to the X-ray transmission window 12 and the window frame 13 and is input to the electron detection preamplifier 23. Thus, the absorbed electrons flow out from the X-ray detector 1 as a current. The electron detection preamplifier 23 converts the input current into a voltage signal, amplifies the voltage signal, and outputs the voltage signal to the control unit 3. Further, when the voltage application unit 24 applies a bias voltage to the X-ray transmission window 12 and the window frame 13, the reflected electrons and secondary electrons collide with the X-ray transmission window 12 and the window frame 13. The absorbed electrons generated by the collision of the reflected electrons and the secondary electrons are input to the electron detection preamplifier 23 as a current. Similarly, the electron detection preamplifier 23 outputs a voltage signal caused by the reflected electrons and the secondary electrons to the control unit 3.
　制御部３は、パルスシェーパ２２から出力されたＸ線のエネルギーを示す信号をインタフェース部３７で受け付け、信号をエネルギー別にカウントし、Ｘ線のエネルギーとカウント数とを対応付けたＸ線のスペクトルを生成する。Ｘ線検出用プリアンプ２１、パルスシェーパ２２及び制御部３は、スペクトル生成部に相当する。また、制御部３は、電子検出用プリアンプ２３から出力された電圧信号をインタフェース部３７で受け付け、電圧信号から電子の量を計算する処理を行う。電子検出用プリアンプ２３から出力された電圧信号は、Ｘ線透過窓１２及び窓枠１３に発生した吸収電子の量に対応しており、更に、Ｘ線透過窓１２及び窓枠１３に衝突した電子の量に対応している。ＣＰＵ３１は、電圧信号の値から電子の量を計算する。このとき、制御部３は、電圧印加部２４にバイアス電圧の印加をオフにさせ、バイアス電圧が印加されていない状態で電子の量を計算することにより、Ｘ線透過窓１２及び窓枠１３に衝突した反射電子の量を計測する。電子検出用プリアンプ２３及び制御部３は計測部に相当する。制御部３は、次に、電圧印加部２４にバイアス電圧の印加をオンにさせ、バイアス電圧が印加されている状態で電子の量を計算することにより、Ｘ線透過窓１２及び窓枠１３に衝突した反射電子及び二次電子の合計量を計測する。ＣＰＵ３１は、次に、バイアス電圧が印加されている状態で計算した電子の量から、バイアス電圧が印加されていない状態で計算した電子の量を減算することにより、Ｘ線透過窓１２及び窓枠１３に衝突した二次電子の量を計測する。このようにして、電子顕微鏡は、電子線を照射された試料５から発生したＸ線と、反射電子と、二次電子とを検出する。 The control unit 3 receives a signal indicating the X-ray energy output from the pulse shaper 22 by the interface unit 37, counts the signal for each energy, and generates an X-ray spectrum in which the X-ray energy is associated with the count number. Generate. The X-ray detection preamplifier 21, the pulse shaper 22, and the control unit 3 correspond to a spectrum generation unit. In addition, the control unit 3 receives the voltage signal output from the electron detection preamplifier 23 by the interface unit 37 and performs a process of calculating the amount of electrons from the voltage signal. The voltage signal output from the electron detection preamplifier 23 corresponds to the amount of absorbed electrons generated in the X-ray transmission window 12 and the window frame 13, and further, the electrons colliding with the X-ray transmission window 12 and the window frame 13. Corresponds to the amount of. The CPU 31 calculates the amount of electrons from the value of the voltage signal. At this time, the control unit 3 turns off the application of the bias voltage to the voltage application unit 24 and calculates the amount of electrons in a state where the bias voltage is not applied, so that the X-ray transmission window 12 and the window frame 13 Measure the amount of backscattered electrons. The electron detection preamplifier 23 and the control unit 3 correspond to a measurement unit. Next, the control unit 3 turns on the application of the bias voltage to the voltage application unit 24 and calculates the amount of electrons in a state where the bias voltage is applied, so that the X-ray transmission window 12 and the window frame 13 are applied. The total amount of reflected electrons and secondary electrons that collided is measured. Next, the CPU 31 subtracts the amount of electrons calculated in a state where no bias voltage is applied from the amount of electrons calculated in a state where a bias voltage is applied, so that the X-ray transmission window 12 and the window frame are subtracted. The amount of secondary electrons that collided with 13 is measured. In this way, the electron microscope detects X-rays generated from the sample 5 irradiated with the electron beam, reflected electrons, and secondary electrons.
　電子レンズ系４２が電子線の方向を順次変更することにより、電子線は試料５を走査する。制御部３は、電子レンズ系４２の動作を制御し、試料５上で電子線を照射された部分の位置を特定する。電子線が試料５を走査することに伴い、試料５上で電子線を照射された部分から発生したＸ線、反射電子及び二次電子が順次検出される。制御部３は、試料５上の電子線を照射された複数の部分で発生したＸ線のスペクトルを順次生成し、ＣＰＵ３１は、試料５上で電子線を照射された部分の位置とＸ線のスペクトルとを関連付けて、Ｘ線スペクトルの分布を生成する。また、制御部３は、試料５上の電子線を照射された複数の部分で発生した反射電子の量を順次計測し、ＣＰＵ３１は、試料５上で電子線を照射された部分の位置と反射電子の量とを関連付けて、反射電子像を生成する。反射電子像は、試料５上で発生した反射電子の量の分布である。同様に、制御部３は、試料５上の電子線を照射された複数の部分で発生した二次電子の量を順次計測し、ＣＰＵ３１は、試料５上で電子線を照射された部分の位置と二次電子の量とを関連付けて、二次電子像を生成する。ＣＰＵ３１は、Ｘ線スペクトルの分布を表すデータ、反射電子像を表すデータ、及び二次電子像を表すデータを記憶部３４に記憶させる。 The electron lens system 42 sequentially changes the direction of the electron beam, so that the electron beam scans the sample 5. The control unit 3 controls the operation of the electron lens system 42 and specifies the position of the portion irradiated with the electron beam on the sample 5. As the electron beam scans the sample 5, X-rays, reflected electrons, and secondary electrons generated from the portion irradiated with the electron beam on the sample 5 are sequentially detected. The control unit 3 sequentially generates X-ray spectra generated in a plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 detects the position of the portion irradiated with the electron beam on the sample 5 and the X-rays. An X-ray spectrum distribution is generated in association with the spectrum. In addition, the control unit 3 sequentially measures the amount of reflected electrons generated in a plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 reflects the position and reflection of the portion irradiated with the electron beam on the sample 5. A backscattered electron image is generated in association with the amount of electrons. The reflected electron image is a distribution of the amount of reflected electrons generated on the sample 5. Similarly, the control unit 3 sequentially measures the amount of secondary electrons generated in the plurality of portions irradiated with the electron beam on the sample 5, and the CPU 31 determines the position of the portion irradiated with the electron beam on the sample 5. A secondary electron image is generated by associating the secondary electron quantity with the amount of secondary electrons. The CPU 31 stores data representing the X-ray spectrum distribution, data representing the reflected electron image, and data representing the secondary electron image in the storage unit 34.
　制御部３は、記憶部３４に記憶したデータに基づいて、Ｘ線スペクトルの分布を表す画像、反射電子像を表す画像、及び二次電子像を表す画像を表示部３６に表示することができる。制御部３は、操作部３５で使用者からの操作を受け付け、受け付けた操作に従って、使用者が所望する画像を表示する。また、制御部３は、Ｘ線のスペクトルから試料５に含まれる元素の種類及び量を特定し、試料５上の元素分布を生成する処理を行ってもよい。この制御部３は、試料５上の元素分布を表す画像を表示部３６に表示する。 Based on the data stored in the storage unit 34, the control unit 3 can display an image representing the X-ray spectrum distribution, an image representing the reflected electron image, and an image representing the secondary electron image on the display unit 36. . The control unit 3 receives an operation from the user through the operation unit 35, and displays an image desired by the user according to the received operation. Further, the control unit 3 may specify the type and amount of the element contained in the sample 5 from the X-ray spectrum and perform a process of generating an element distribution on the sample 5. The control unit 3 displays an image representing the element distribution on the sample 5 on the display unit 36.
　以上詳述した如く、本実施の形態においては、Ｘ線検出器１が備えるＸ線透過窓１２の外面及び窓枠１３に導電性を持たせており、Ｘ線透過窓１２とＸ線検出素子１１とは電気的に絶縁されている。電子線の照射により試料５からＸ線及び反射電子が発生する。Ｘ線は、Ｘ線透過窓１２を透過し、Ｘ線検出器１内のＸ線検出素子１１で検出される。反射電子は、Ｘ線透過窓１２及び窓枠１３に衝突し、吸収電子が電流となって流れ、反射電子の量が検出される。このように、本実施の形態に係る電子顕微鏡は、Ｘ線検出器１とは別に反射電子検出器を備える事無く、Ｘ線と反射電子とを個別に検出することが可能である。Ｘ線と反射電子とを個別に検出するので、Ｘ線検出器で反射電子検出器を兼ねた従来の装置での問題は発生しない。例えば、Ｘ線のスペクトルと反射電子のスペクトルとを分離する必要が無いので、スペクトルが分離できるような十分な量の反射電子を検出する必要は無い。このため、検出に最低限必要な反射電子の量が抑制され、反射電子像を生成するために必要な時間の長大化が防止される。また、スペクトルが分離できるようにＳ／Ｎ比又はＸ線及び反射電子の比率を調整するべくＸ線透過窓の厚みを調整する必要が無くなる。また、Ｘ線検出素子１１ではＸ線のみを検出し、反射電子を検出しないので、Ｘ線及び反射電子を同一の検出器で検出する場合に比べて、不感時間が短くなる。このため、スペクトルの分解能の悪化、検出効率の悪化、及び検出器の短寿命化が防止される。 As described above in detail, in the present embodiment, the outer surface of the X-ray transmission window 12 and the window frame 13 provided in the X-ray detector 1 are made conductive, and the X-ray transmission window 12 and the X-ray detection element are provided. 11 is electrically insulated. X-rays and reflected electrons are generated from the sample 5 by the electron beam irradiation. X-rays pass through the X-ray transmission window 12 and are detected by the X-ray detection element 11 in the X-ray detector 1. The reflected electrons collide with the X-ray transmission window 12 and the window frame 13, the absorbed electrons flow as current, and the amount of reflected electrons is detected. As described above, the electron microscope according to the present embodiment can individually detect X-rays and reflected electrons without providing a reflected electron detector separately from the X-ray detector 1. Since X-rays and backscattered electrons are detected separately, there is no problem with the conventional apparatus that also functions as a backscattered electron detector with an X-ray detector. For example, since it is not necessary to separate the spectrum of X-rays and the spectrum of reflected electrons, it is not necessary to detect a sufficient amount of reflected electrons so that the spectrum can be separated. For this reason, the minimum amount of reflected electrons required for detection is suppressed, and the length of time required to generate a reflected electron image is prevented. Further, it is not necessary to adjust the thickness of the X-ray transmission window in order to adjust the S / N ratio or the ratio of X-rays and reflected electrons so that the spectra can be separated. In addition, since the X-ray detection element 11 detects only X-rays and does not detect reflected electrons, the dead time is shorter than when detecting X-rays and reflected electrons with the same detector. For this reason, deterioration in spectral resolution, deterioration in detection efficiency, and shortening of the lifetime of the detector are prevented.
　また、本実施の形態においては、Ｘ線透過窓１２の厚みを、反射電子が透過する確率が所定値以下になるように定めていることによって、Ｘ線と反射電子とがＸ線透過窓１２によって分離され、確実に個別に検出されることになる。また、本実施の形態においては、電子顕微鏡は、Ｘ線透過窓１２及び窓枠１３に正のバイアス電圧を印加した場合と印加しない場合とで電子の量を計測し、計測した電子の量の差を計算することで二次電子の量を計測する。これにより、電子顕微鏡は、二次電子をも個別に検出することが可能となる。二次電子検出器を別に備える必要が無くなり、電子顕微鏡の各部の配置が容易となる。また、本実施の形態においては、Ｘ線検出器１は電子線を通過させるための貫通孔１４が形成されている。これにより、図１に示すように、電子レンズ系４２と試料台４３との間にＸ線検出器１を配置して、Ｘ線検出器１を可及的に試料５へ近づけることが可能となる。試料５から発生するＸ線及び電子はいずれも、検出位置が試料５に近いほど強度が大きくなる。Ｘ線及び電子を同じ位置で検出することができるＸ線検出器１を可及的に試料へ近づけることによって、Ｘ線、反射電子及び二次電子の検出効率が向上する。 In the present embodiment, the thickness of the X-ray transmission window 12 is determined such that the probability that the reflected electrons are transmitted is less than or equal to a predetermined value. Are separated and reliably detected individually. In the present embodiment, the electron microscope measures the amount of electrons when a positive bias voltage is applied to the X-ray transmission window 12 and the window frame 13 and when it is not applied, and the measured amount of electrons is measured. The amount of secondary electrons is measured by calculating the difference. As a result, the electron microscope can individually detect secondary electrons. It is not necessary to separately provide a secondary electron detector, and the arrangement of each part of the electron microscope is facilitated. In the present embodiment, the X-ray detector 1 is formed with a through hole 14 for allowing an electron beam to pass therethrough. As a result, as shown in FIG. 1, the X-ray detector 1 can be arranged between the electron lens system 42 and the sample stage 43 so that the X-ray detector 1 can be as close to the sample 5 as possible. Become. The X-rays and electrons generated from the sample 5 both increase in intensity as the detection position is closer to the sample 5. By bringing the X-ray detector 1 capable of detecting X-rays and electrons at the same position as close to the sample as possible, the detection efficiency of X-rays, reflected electrons, and secondary electrons is improved.
　なお、本実施の形態においては、Ｘ線検出器１が複数のＸ線検出素子１１を備えた形態を示したが、Ｘ線検出器１は単一のＸ線検出素子１１を備えた形態であってもよい。また、本実施の形態においては、Ｘ線透過窓１２が一体である形態を示したが、Ｘ線検出器１は複数のＸ線透過窓１２を備えた形態であってもよい。 In the present embodiment, the X-ray detector 1 includes a plurality of X-ray detection elements 11. However, the X-ray detector 1 includes a single X-ray detection element 11. There may be. In the present embodiment, the X-ray transmission window 12 is integrated. However, the X-ray detector 1 may have a plurality of X-ray transmission windows 12.
（実施の形態２）
　図３は、実施の形態２に係る電子顕微鏡の構成を示すブロック図である。本実施の形態に係る電子顕微鏡は、複数のＸ線検出器１を備えている。図中にはＸ線検出器１の断面を示している。Ｘ線検出器１は、電子レンズ系４２と試料台４３との間の位置から外れた位置に配置されている。Ｘ線検出器１は、実施の形態１と同様に、Ｘ線検出素子１１と、Ｘ線透過窓１２と、窓枠１３とを備えており、Ｘ線透過窓１２の少なくとも外面と窓枠１３とは導電性を有している。Ｘ線透過窓１２及び窓枠１３は、Ｘ線検出素子１１から電気的に絶縁されている。また、Ｘ線検出器１には、貫通孔１４が形成されていない。複数のＸ線検出器１は、夫々に、Ｘ線透過窓１２を試料台４３に対向させて配置されている。電子顕微鏡は、実施の形態１と同様に、Ｘ線検出用プリアンプ２１、パルスシェーパ２２、電子検出用プリアンプ２３、電圧印加部２４及び制御部３を備えているが、図３中では省略している。夫々のＸ線検出器１が備えるＸ線検出素子１１はＸ線検出用プリアンプ２１に電気的に接続されており、Ｘ線透過窓１２の外面及び窓枠１３は電子検出用プリアンプ２３に電気的に接続されている。 (Embodiment 2)
FIG. 3 is a block diagram showing the configuration of the electron microscope according to the second embodiment. The electron microscope according to the present embodiment includes a plurality of X-ray detectors 1. In the drawing, a cross section of the X-ray detector 1 is shown. The X-ray detector 1 is disposed at a position deviated from the position between the electron lens system 42 and the sample stage 43. As in the first embodiment, the X-ray detector 1 includes an X-ray detection element 11, an X-ray transmission window 12, and a window frame 13, and at least the outer surface of the X-ray transmission window 12 and the window frame 13. And have conductivity. The X-ray transmission window 12 and the window frame 13 are electrically insulated from the X-ray detection element 11. Further, the through-hole 14 is not formed in the X-ray detector 1. Each of the plurality of X-ray detectors 1 is arranged with the X-ray transmission window 12 facing the sample stage 43. As in the first embodiment, the electron microscope includes an X-ray detection preamplifier 21, a pulse shaper 22, an electron detection preamplifier 23, a voltage application unit 24, and a control unit 3, which are omitted in FIG. Yes. The X-ray detection element 11 provided in each X-ray detector 1 is electrically connected to the X-ray detection preamplifier 21, and the outer surface of the X-ray transmission window 12 and the window frame 13 are electrically connected to the electron detection preamplifier 23. It is connected to the.
　電子銃４１は、試料台４３上の試料５へ電子線を照射する。試料５から発生したＸ線は、各Ｘ線検出器１のＸ線透過窓１２を通過してＸ線検出器１で検出される。電圧印加部２４は夫々のＸ線透過窓１２及び窓枠１３に正のバイアス電圧を印加し、電子線の照射により試料５から発生した反射電子及び二次電子は、各Ｘ線検出器１のＸ線透過窓１２に衝突する。また、電圧印加部２４が夫々のＸ線透過窓１２及び窓枠１３に正のバイアス電圧を印加していない状態で、電子線の照射により試料５から発生した反射電子は、各Ｘ線検出器１のＸ線透過窓１２に衝突する。図３中には、電子の経路を実線矢印で示し、Ｘ線を破線矢印で示している。Ｘ線検出用プリアンプ２１、パルスシェーパ２２、電子検出用プリアンプ２３、電圧印加部２４及び制御部３は実施の形態１と同様の処理を実行し、制御部３は、Ｘ線スペクトルの分布、反射電子像及び二次電子像を生成し、夫々を表すデータを記憶部３４に記憶する。 The electron gun 41 irradiates the sample 5 on the sample stage 43 with an electron beam. X-rays generated from the sample 5 pass through the X-ray transmission window 12 of each X-ray detector 1 and are detected by the X-ray detector 1. The voltage application unit 24 applies a positive bias voltage to each of the X-ray transmission window 12 and the window frame 13, and the reflected electrons and secondary electrons generated from the sample 5 due to the irradiation of the electron beam are applied to each X-ray detector 1. It collides with the X-ray transmission window 12. In addition, in the state where the voltage application unit 24 does not apply a positive bias voltage to the X-ray transmission window 12 and the window frame 13, the reflected electrons generated from the sample 5 by the irradiation of the electron beam are detected by each X-ray detector. 1 X-ray transmission window 12 collides. In FIG. 3, electron paths are indicated by solid arrows, and X-rays are indicated by broken arrows. The X-ray detection preamplifier 21, the pulse shaper 22, the electron detection preamplifier 23, the voltage application unit 24, and the control unit 3 execute the same processing as in the first embodiment, and the control unit 3 performs the distribution and reflection of the X-ray spectrum. An electronic image and a secondary electron image are generated, and data representing each is stored in the storage unit 34.
　本実施の形態においても、電子顕微鏡は、Ｘ線検出器１とは別に反射電子検出器を備える事無く、Ｘ線、反射電子及び二次電子を個別に検出することが可能である。従って、本実施の形態では、実施の形態１と同様に、反射電子像を生成するために必要な時間の長大化が防止され、スペクトルの分解能の悪化、検出効率の悪化、及び検出器の短寿命化が防止される。 Also in this embodiment, the electron microscope can separately detect X-rays, reflected electrons, and secondary electrons without providing a reflected electron detector separately from the X-ray detector 1. Therefore, in the present embodiment, as in the first embodiment, it is possible to prevent an increase in the time required for generating a backscattered electron image, a deterioration in spectral resolution, a deterioration in detection efficiency, and a short detector. Life expectancy is prevented.
　なお、本実施の形態においては、同形状の複数のＸ線検出器１を対称な位置に配置した形態を示したが、電子顕微鏡は、これに限るものではなく、形状の異なる複数のＸ線検出器１を備えた形態であってもよく、複数のＸ線検出器１を非対称な位置に配置した形態であってもよい。また、複数のＸ線検出器１は、試料台４３からの距離が異なる位置に配置されていてもよい。また、電子顕微鏡は、電子レンズ系４２と試料台４３との間の位置から外れた位置に単一のＸ線検出器１を配置した形態であってもよい。 In the present embodiment, a form in which a plurality of X-ray detectors 1 having the same shape are arranged at symmetrical positions is shown. However, the electron microscope is not limited to this, and a plurality of X-rays having different shapes are used. The form provided with the detector 1 may be sufficient, and the form which has arrange | positioned the several X-ray detector 1 in the asymmetrical position may be sufficient. Further, the plurality of X-ray detectors 1 may be arranged at positions where the distance from the sample stage 43 is different. Further, the electron microscope may have a form in which the single X-ray detector 1 is disposed at a position deviated from the position between the electron lens system 42 and the sample stage 43.
　また、以上の実施の形態１及び２においては、窓枠１３が導電性を有している形態を示したが、電子顕微鏡は、これに限るものではなく、窓枠１３が導電性を有していない形態であってもよい。この形態では、Ｘ線透過窓１２の外面に電子検出用プリアンプ２３が電気的に接続されており、電子顕微鏡は、Ｘ線透過窓１２に衝突した電子の量を計測する。また、実施の形態１及び２においては、試料５に対して正のバイアス電圧をＸ線透過窓１２に印加する形態を示したが、電子顕微鏡は、Ｘ線透過窓１２に対して負のバイアス電圧を試料５に印加する形態であってもよい。また、実施の形態１及び２においては、電圧印加部２４を利用して二次電子を検出する形態を示したが、電子顕微鏡は、これに限るものではなく、電圧印加部２４を備えておらず、Ｘ線検出器１を用いた二次電子検出を行わない形態であってもよい。この形態では、電子顕微鏡は、Ｘ線検出器１とは別に、二次電子検出器を備えている。また、実施の形態１及び２においては、Ｘ線検出素子１１はＳＤＤであるとしたが、Ｘ線検出素子１１はＳＤＤ以外の検出素子であってもよい。また、実施の形態１及び２においては、本発明の電子検出装置はＳＥＭであるとしたが、これに限るものではなく、本発明の電子検出装置はその他の装置であってもよい。例えば、電子検出装置は、ＴＥＭ（透過型電子顕微鏡）又はマイクロアナライザーにＸ線検出器１が組み込まれた形態であってもよい。また、電子検出装置は、自身では試料５へ電子線を照射する機能を備えていない形態であってもよい。 In the first and second embodiments described above, the window frame 13 has a conductivity. However, the electron microscope is not limited to this, and the window frame 13 has a conductivity. It may be in a form that is not. In this embodiment, an electron detection preamplifier 23 is electrically connected to the outer surface of the X-ray transmission window 12, and the electron microscope measures the amount of electrons that have collided with the X-ray transmission window 12. In the first and second embodiments, the positive bias voltage is applied to the X-ray transmission window 12 with respect to the sample 5, but the electron microscope has a negative bias with respect to the X-ray transmission window 12. The voltage may be applied to the sample 5. Moreover, in Embodiment 1 and 2, although the form which detects a secondary electron using the voltage application part 24 was shown, the electron microscope is not restricted to this, The voltage application part 24 is not provided. Alternatively, the secondary electron detection using the X-ray detector 1 may not be performed. In this embodiment, the electron microscope includes a secondary electron detector separately from the X-ray detector 1. In the first and second embodiments, the X-ray detection element 11 is an SDD, but the X-ray detection element 11 may be a detection element other than the SDD. In Embodiments 1 and 2, the electron detection device of the present invention is an SEM. However, the present invention is not limited to this, and the electron detection device of the present invention may be another device. For example, the electron detection device may have a form in which the X-ray detector 1 is incorporated in a TEM (transmission electron microscope) or a microanalyzer. Further, the electron detector itself may not have a function of irradiating the sample 5 with an electron beam.
　１　Ｘ線検出器
　１１　Ｘ線検出素子
　１２　Ｘ線透過窓
　１３　窓枠
　２１　Ｘ線検出用プリアンプ
　２２　パルスシェーパ
　２３　電子検出用プリアンプ
　２４　電圧印加部
　３　制御部
　４１　電子銃
　４２　電子レンズ系
　４３　試料台
　５　試料 DESCRIPTION OF SYMBOLS 1 X-ray detector 11 X-ray detection element 12 X-ray transmissive window 13 Window frame 21 X-ray detection preamplifier 22 Pulse shaper 23 Electron detection preamplifier 24 Voltage application part 3 Control part 41 Electron gun 42 Electron lens system 43 Sample stand 5 sample

Claims (8)

  1. 　Ｘ線を透過させるＸ線透過窓と、該Ｘ線透過窓を透過したＸ線を検出するＸ線検出素子とを備える検出器において、
    　前記Ｘ線透過窓の外面は導電性を有しており、
    　前記Ｘ線透過窓は、外面に電子が衝突することによって発生した吸収電子が電流として流出するように構成してあること
    　を特徴とする検出器。     In a detector comprising an X-ray transmission window that transmits X-rays, and an X-ray detection element that detects X-rays transmitted through the X-ray transmission window,
    The outer surface of the X-ray transmission window has conductivity,
    The X-ray transmission window is configured such that absorbed electrons generated by electrons colliding with the outer surface flow out as current.
  2. 　前記Ｘ線透過窓を支持する導電性の窓枠を更に備えること
    　を特徴とする請求項１に記載の検出器。     The detector according to claim 1, further comprising a conductive window frame that supports the X-ray transmission window.
  3. 　請求項１又は２に記載の検出器と、
    　該検出器が有するＸ線検出素子に電気的に接続されており、該Ｘ線検出素子が検出したＸ線のスペクトルを生成するスペクトル生成部と、
    　前記検出器が有するＸ線透過窓の外面に電気的に接続されており、該Ｘ線透過窓に衝突した電子に起因して発生する電流に基づいて、前記Ｘ線透過窓に衝突した電子の量を計測する計測部と
    　を備えることを特徴とする電子検出装置。     A detector according to claim 1 or 2, and
    A spectrum generation unit that is electrically connected to an X-ray detection element included in the detector and generates an X-ray spectrum detected by the X-ray detection element;
    The detector is electrically connected to the outer surface of the X-ray transmission window, and based on the current generated due to the electrons colliding with the X-ray transmission window, the electrons colliding with the X-ray transmission window An electronic detection apparatus comprising: a measurement unit that measures a quantity.
  4. 　試料を電子線で走査する走査部と、
    　請求項１又は２に記載の検出器と、
    　該検出器が有するＸ線検出素子に接続されており、電子線によって試料から発生して前記Ｘ線検出素子が検出したＸ線のスペクトルを生成するスペクトル生成部と、
    　前記検出器が有するＸ線透過窓に接続されており、電子線によって試料から発生して前記Ｘ線透過窓に衝突した電子に起因して発生する電流に基づいて、試料から発生した電子の量を計測する計測部と、
    　該計測部が計測した電子の量に基づいて、前記走査部が走査した試料の電子像を生成する電子像生成部と
    　を備えることを特徴とする電子検出装置。     A scanning unit that scans the sample with an electron beam;
    A detector according to claim 1 or 2, and
    A spectrum generation unit that is connected to an X-ray detection element included in the detector and generates an X-ray spectrum generated from a sample by an electron beam and detected by the X-ray detection element;
    The amount of electrons generated from the sample based on the current that is connected to the X-ray transmission window of the detector and that is generated from the sample by the electron beam and collides with the X-ray transmission window A measurement unit for measuring
    An electron detection apparatus comprising: an electron image generation unit configured to generate an electronic image of a sample scanned by the scanning unit based on an amount of electrons measured by the measurement unit.
  5. 　試料と前記Ｘ線透過窓との間に、試料に対して前記Ｘ線透過窓が正となるバイアス電圧を印加する電圧印加部を更に備えること
    　を特徴とする請求項４に記載の電子検出装置。     The electron detection device according to claim 4, further comprising: a voltage application unit that applies a bias voltage that makes the X-ray transmission window positive with respect to the sample between the sample and the X-ray transmission window. .
  6. 　前記電圧印加部が前記バイアス電圧を印加した場合と印加しなかった場合とで前記計測部が計測した電子の量の差を計算する計算部を更に備えること
    　を特徴とする請求項５に記載の電子検出装置。     The calculation unit according to claim 5, further comprising a calculation unit that calculates a difference in the amount of electrons measured by the measurement unit when the voltage application unit applies the bias voltage and when the bias voltage is not applied. Electronic detection device.
  7. 　前記Ｘ線透過窓の厚みは、前記走査部が試料へ照射する電子線のエネルギーに応じて、前記電子線によって試料から発生した電子が前記Ｘ線透過窓を透過する確率が所定値以下になるように定められていること
    　を特徴とする請求項４乃至６のいずれか一つに記載の電子検出装置。     The thickness of the X-ray transmission window is such that the probability that electrons generated from the sample by the electron beam pass through the X-ray transmission window is less than a predetermined value according to the energy of the electron beam irradiated to the sample by the scanning unit. The electron detection device according to claim 4, wherein the electron detection device is defined as follows.
  8. 　前記検出器は、貫通孔を有しており、前記走査部が試料へ照射する電子線が前記貫通孔を通過する位置に配置されていること
    　を特徴とする請求項４乃至７のいずれか一つに記載の電子検出装置。     8. The detector according to claim 4, wherein the detector has a through hole, and the electron beam irradiated to the sample by the scanning unit passes through the through hole. The electronic detection device according to one.
PCT/JP2015/053061 2014-02-18 2015-02-04 Detector and electron detection device WO2015125603A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11444213B2 (en) 2017-06-05 2022-09-13 Fondazione Bruno Kessler Radiation detector and radiation detection apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5448481A (en) * 1977-09-26 1979-04-17 Jeol Ltd Electron ray unit
JP2013160614A (en) * 2012-02-03 2013-08-19 Horiba Ltd X-ray detection device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5448481A (en) * 1977-09-26 1979-04-17 Jeol Ltd Electron ray unit
JP2013160614A (en) * 2012-02-03 2013-08-19 Horiba Ltd X-ray detection device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11444213B2 (en) 2017-06-05 2022-09-13 Fondazione Bruno Kessler Radiation detector and radiation detection apparatus

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