WO2015029201A1 - Détecteur de spin, dispositif à faisceau de particules chargées et dispositif spectroscopique de photoémission - Google Patents

Détecteur de spin, dispositif à faisceau de particules chargées et dispositif spectroscopique de photoémission Download PDF

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Publication number
WO2015029201A1
WO2015029201A1 PCT/JP2013/073243 JP2013073243W WO2015029201A1 WO 2015029201 A1 WO2015029201 A1 WO 2015029201A1 JP 2013073243 W JP2013073243 W JP 2013073243W WO 2015029201 A1 WO2015029201 A1 WO 2015029201A1
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Prior art keywords
spin
detector
detectors
charged particles
sample
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PCT/JP2013/073243
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English (en)
Japanese (ja)
Inventor
照生 孝橋
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株式会社日立製作所
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Priority to JP2015533879A priority Critical patent/JP6177919B2/ja
Priority to PCT/JP2013/073243 priority patent/WO2015029201A1/fr
Publication of WO2015029201A1 publication Critical patent/WO2015029201A1/fr

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    • 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
    • H01J2237/245—Detection characterised by the variable being measured
    • H01J2237/24507—Intensity, dose or other characteristics of particle beams or electromagnetic radiation
    • H01J2237/24557—Spin polarisation (particles)

Definitions

  • the present invention relates to a detector, an apparatus, or an analyzer for detecting spin of charged particles.
  • the present invention relates to an analyzer that operates in a vacuum chamber and detects individual spins of charged particles (electrons).
  • a Mott detector is known as an electron beam spin detector used in a spin-polarized scanning electron microscope (spin SEM) and a spin-resolved photoelectron spectrometer, but this is more sensitive than an electron detector. An order of magnitude lower. For this reason, various research laboratories are working on the structure of the Mott detector to improve the efficiency. However, at present, the improvement is only a few times at most, and it is unlikely to see dramatic improvement in the future.
  • a spin-polarized electron beam is irradiated on a ferromagnetic material, and the phenomenon that the current absorbed in the ferromagnetic material depends on the spin-polarization degree of the incident electron beam is used.
  • a detector has been proposed and is referred to as a VLEEDery (Very-Low-Energy Electorn Diffraction) detector (for example, Non-Patent Document 1).
  • the principle is derived from the fact that the electronic band structure of ferromagnets differs depending on the direction of electron spin, and the probability of incorporation into the band differs depending on the direction of electron spin.
  • the electronic band structure of ferromagnets differs depending on the direction of electron spin, and the probability of incorporation into the band differs depending on the direction of electron spin.
  • there are only electron levels with spins in one direction so electrons with spins in that direction are absorbed by ferromagnets, but most electrons with opposite spins are absorbed. Reflected.
  • a VLEED detector using the spin direction dependence of such an electronic band structure is about two orders of magnitude more efficient than a conventional Mott detector, and is small and inexpensive. It is often used especially in the field of spin-resolved photoelectron spectroscopy.
  • VLEED detectors are oxygen single-crystal (001) surfaces with oxygen termination. Also, the cleanliness of the surface is extremely important, and when used for several days, a cleaning process such as annealing is required.
  • a VLEED detector the energy of electrons that collide with the target is strictly defined.
  • a VLEED detector described in Non-Patent Document 1 must be within a range of about 6V ⁇ 1V.
  • spin-polarized electrons analyzed by, for example, spin SEM are secondary electrons emitted from the sample, and thus have a distribution of about 0-20 eV. In this state, even if measured with a VLEED detector, its efficiency The goodness cannot be demonstrated.
  • an object of the present invention is to make the VLEED detector applicable to an electron flux having a large energy dispersion such as secondary electrons.
  • a small and inexpensive electron spin detector that can decompose spins of electron bundles with large energy dispersion with high efficiency and that does not require acceleration of the electron beam to the 100 kV level.
  • a spin detector is a spin detector used in a charged particle beam apparatus that detects charged particles having a spin, and the charged particle beam apparatus irradiates a sample with charged particles.
  • the first and second detectors are arranged in order from the sample to detect the secondary charged particles generated by the secondary optical system and transported by the secondary optical system.
  • the detector is a detector whose reflectance varies depending on the spin direction of the incident charged particle to be measured, and the absolute value of the potential applied to the first detector is the same as the potential applied to the second detector. It is characterized by being lower than the absolute value.
  • the charged particle beam apparatus is a charged particle beam apparatus for detecting charged particles having a spin, and transports secondary charged particles generated from the irradiation optical system for irradiating the sample with charged particles.
  • the absolute value of the potential applied to the first detector is lower than the absolute value of the potential applied to the second detector.
  • the photoelectron spectrometer of the present invention is a photoelectron spectrometer that detects charged particles having a spin, an irradiation optical system that irradiates a sample with X-rays, and a secondary optical system that carries a photoelectron bundle generated from the sample.
  • a first detector and a second detector arranged in order from the sample, and the first and second detectors have a detector whose reflectivity varies depending on the spin direction of incident photoelectrons.
  • the absolute value of the potential applied to the first detector is lower than the absolute value of the potential applied to the second detector.
  • the present invention it was considered to measure the spin polarization by making the energy-resolved electron to be measured enter a plurality of VLEED detectors.
  • a plurality of VLEED detectors are sequentially arranged as viewed from the incident direction of the electron beam. Then, a voltage is applied to each VLEED detector so that the voltage decreases in order from the incident direction of electrons (the absolute value increases in the minus direction).
  • the measured electrons cross the equipotential surface every time they pass through the line of VLEED detectors arranged in order, and when viewed from the electrons, the potential energy advances in a higher direction, and the speed is reduced accordingly.
  • the slowed-down electrons lose their straightness and tend to deviate from the orbit.
  • the electrons with the lowest energy are deviated from the orbit in order, and are incident on the VLEED detector arranged near the electron orbit to be measured. If the trajectory is deviated enough to enter the VLEED detector (for example, about 6V), the spin polarization degree of electrons incident on the VLEED detector can be measured efficiently. In this case, the larger the energy dispersion of the electron flux to be measured, the greater the number of VLEED detectors.
  • VLEED detector indicates an element solid such as an iron single crystal plate, and an assembly assembled as an assembly thereof is called a “spin detector”.
  • a detector that decomposes spins of an electron beam bundle having a large energy dispersion with high efficiency is provided by arranging spin detection elements having a narrow energy acceptance such as a VLEED detector in an array. Also, it is possible to provide a small and inexpensive electron spin detector that does not need to accelerate the electron beam to the 100 kV level.
  • FIG. 1 shows an embodiment in which a VLEED detector is arranged to be used as a spin detector of the present invention.
  • the electron beam to be measured 101 is transported from the left side in a specific energy state (for example, 10 kV level) by a transport optical system 102 that moves electrons to a certain place.
  • a transport optical system 102 that moves electrons to a certain place.
  • the acceleration voltage needs to be increased to some extent.
  • the energy of the electron beam must be lowered to about several volts, so the decelerating lens 105 is disposed immediately before entering the spin detector.
  • the electron beam to be measured 101 is decelerated, it proceeds to a portion where the right VLEED detector 104 is arranged side by side.
  • An electric potential is further applied to the VLEED detector so as to decelerate the electron beam 101 to be measured. Therefore, the equipotential line 103 is bent as shown in the figure, thereby increasing the opening angle of the electron beam and the beam diameter. Spread, especially low energy electrons deviate from the optical axis.
  • a voltage for example, 6V
  • the energy is incident on the VLEED detector installed beside the optical axis.
  • it is more effective to tilt the VLEED detector 104 so that electrons can be incident at an angle close to vertical.
  • the electron beam to be measured 101 whose trajectory travels straight ahead travels to the right as shown by the arrow in FIG.
  • the VLEED detector 104 arranged in the periphery is set to a lower potential as it goes to the right in FIG. 1, the energy of the electron beam 101 to be measured becomes lower as it goes to the right. Then, at a stage where the energy is gradually lowered (about 6 V), the energy deviates from the optical axis, enters a VLEED detector arranged beside the optical axis, and the spin polarization is measured.
  • the high sensitivity of the VLEED detector depends on the energy width of the electrons (here about 2 eV). So, for example, in order to analyze secondary electrons with an energy width of 0-20 eV, if about 10 stages of VLEED detectors with an energy width of about 2 eV are arranged, the spin polarization of most secondary electrons can be efficiently obtained. Can be detected.
  • VLEED detectors are arranged.
  • a multilayer magnetoresistive element having a small energy acceptance can be implemented as a high-efficiency spin detector in the same system as in this example.
  • the VLEED detector described as a single plate in FIG. 1 is configured by a plurality of VLEED detectors in consideration of easiness of taking in electrons, and can be arranged in an arc shape, for example. .
  • FIG. 2 shows another embodiment in which the VLEED detector 204 is arranged to be used as the spin detector of the present invention.
  • the VLEED detector 204 is not arranged at a position symmetrical to the electron orbit, but an electrode 206 extending in the electron orbit direction is arranged on one side, and the VLEED detector 204 is arranged at the opposite position. Yes. Accordingly, the equipotential surface of the portion through which the measured electron beam 201 passes is asymmetric with respect to the trajectory of the measured electron beam 201.
  • the VLEED detector 204 has a lower potential as it goes to the right, and the same or lower potential is applied to the electrode 206 as the VLEED detector 204 in the final stage.
  • the electron beam 201 to be measured is an electron beam bundle having an energy width, but the energy decreases as it advances to the right, for example, the energy decreases to 6 V at which the VLEED detector 204 can efficiently detect electron spin.
  • the orbit is largely deviated from the optical axis, and enters the VLEED detector 204 arranged on the side of the optical axis, and the spin polarization measurement is performed.
  • FIG. 3 shows another embodiment of the present invention.
  • only the spin in the spin polarization direction 306 of the material constituting the VLEED detector 304 can be resolved.
  • spins in other directions can also be detected.
  • an electric field and a magnetic field having the same structure as an energy analyzer called a Wien filter in which the electric field and the magnetic field are orthogonal to each other or an electron orbit, or a solenoid coil can be considered.
  • any direction of the electron spin can be directed to a direction that can be detected by the spin detector according to the present invention.
  • the spin component perpendicular to the paper surface can be detected in FIG.
  • the spin component in the horizontal direction of the paper surface is detected.
  • the spin component in the vertical direction of the paper surface can be detected by rotating the electron spin by 90 degrees in the direction perpendicular to the paper surface in FIG.
  • FIG. 4 shows an embodiment of a spin-polarized scanning electron microscope equipped with the electron spin detector according to the present invention.
  • a spin-polarized scanning electron microscope is a device that obtains a magnetic domain image by mapping the spin-polarization degree of secondary electrons emitted from a magnetic material sample.
  • Patent Document 1 Japanese Patent Laid-Open No. 60-177539
  • the outline is open to the public.
  • the primary electron beam 402 emitted from the electron gun 401 is applied to the sample 404 set on the sample stage 403. Up to this point, it is the same as a normal SEM, but in a spin-polarized scanning electron microscope, a secondary electron collecting optical system 405 is arranged near the sample, transporting as many secondary electrons 406 as possible, and resolving those spins. There is a need. Therefore, a secondary electron transport optical system 407 for transporting the secondary electrons 406 must be arranged and transported to the spin detection system while adjusting the lens characteristics of these optical systems. An example of the voltage to be applied to each electron lens of the secondary electron collecting optical system 405 and the secondary electron transport optical system 407 is shown in the drawing.
  • the secondary electrons 406 then reach the spin rotator 408, rotate the component of the electron spin to be detected in a direction that can be detected by the electron spin detector 409, and then be transported to the electron spin detector 409. If two spin rotators 408 are mounted as described above, spins in any direction can be directed in the detectable direction.
  • the signal from the spin detector 409 enters the signal processing system 410, and a magnetic domain image is created by the image processing system 411.
  • the image processing system 412 also controls the spin rotator so that it can select which direction spins are imaged.
  • the image processing system 411 is also connected to an electron beam controller 412 that controls the electron gun 401, and fuses the position of the primary electron beam 402 on the sample and the signal from the signal processing system 410 to create a magnetic domain image.
  • the chamber is omitted in this figure.
  • the above-mentioned spin-polarized scanning electron microscope is a technique that has already been reported, but by installing the spin detector 409 according to the present invention, data with much better S / N than before can be obtained. A large amount of data can be acquired in a short time.
  • FIG. 5 shows an embodiment of an ion microscope equipped with a spin detector according to the present invention.
  • the diagram around the sample is basically the same as the spin-polarized scanning electron microscope of FIG. 4, and an optical system that irradiates the sample with a charged particle source or beam that is a source of charged particles, It has a detection system for secondary electrons or reflected electrons generated from the sample by irradiation.
  • the secondary electrons from the sample are produced by ion irradiation, a high secondary electron yield can be expected, and by combining with the high efficiency of the spin detector, an extremely high S / N image can be taken.
  • FIG. 6 shows an embodiment of a photoelectron spectrometer equipped with a spin detector according to the present invention.
  • the electromagnetic wave 604 emitted from the light source 601 passes through the condensing optics 602 and then irradiates the sample 605 set in the ultrahigh vacuum chamber 603.
  • the photoelectrons excited thereby enter the spin detector 608 after passing through the electron lens 606.
  • the spin detector is displayed as a large number of pairs of the VLEED detector 614 and the immediately preceding deceleration lens 613 arranged outside the arc drawn by the electrons.
  • the computer 610 for system control also controls the light source control unit.
  • This method is a method known as spin-resolved photoelectron spectroscopy, but a Mott detector is conventionally used as the spin detector 608, and its sensitivity is not sufficient.
  • VLEED detectors are also used, but only one iron single crystal.
  • 100 traveling direction of electron beam to be measured, 101: electron beam, 102: transport optical system, 103: equipotential line, 104: magnetoresistive element, 105: deceleration lens, 200 ... Electron beam traveling direction, 201 ... Electron beam, 202 ... Transport optical system, 203 ... Equipotential line, 204 ... Magnetoresistive element, 205 ... Deceleration lens, 301 ... Electron beam, 302 ... Spin rotator, 303 ... Spin rotator, 304 ... Magnetoresistive element, 305 ... Deceleration lens, 401 ... Electron gun, 402 ... Primary electron beam, 403 ... Sample stage 404 ... Sample, 405 ... Secondary electron collection optical system, 406 ...

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  • Analytical Chemistry (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

Le détecteur de spin selon la présente invention est équipé d'une pluralité de détecteurs de VLEED (104) disposés au voisinage d'un axe optique d'électrons (101) à mesurer. Une tension est appliquée à chacun des détecteurs de VLEED, laquelle s'abaisse séquentiellement dans la direction de trajet des électrons à mesurer. Lorsque les électrons à mesurer traversent les lignes de détecteurs de VLEED, leur énergie décroît, si bien que les électrons sont pris dans les détecteurs de VLEED séquentiellement. Cela permet d'utiliser un détecteur de VLEED, un détecteur de spin à acceptation d'énergie étroite, pour une détection hautement efficace d'une polarisation de spin possédée par des électrons secondaires avec une dispersion d'énergie, par exemple de l'ordre de 0 à 20 V.
PCT/JP2013/073243 2013-08-30 2013-08-30 Détecteur de spin, dispositif à faisceau de particules chargées et dispositif spectroscopique de photoémission WO2015029201A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2015533879A JP6177919B2 (ja) 2013-08-30 2013-08-30 スピン検出器、及び荷電粒子線装置および光電子分光装置
PCT/JP2013/073243 WO2015029201A1 (fr) 2013-08-30 2013-08-30 Détecteur de spin, dispositif à faisceau de particules chargées et dispositif spectroscopique de photoémission

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PCT/JP2013/073243 WO2015029201A1 (fr) 2013-08-30 2013-08-30 Détecteur de spin, dispositif à faisceau de particules chargées et dispositif spectroscopique de photoémission

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019224919A1 (fr) * 2018-05-22 2019-11-28 株式会社日立ハイテクノロジーズ Dispositif d'analyse de spin
JPWO2019186736A1 (ja) * 2018-03-27 2021-02-12 株式会社日立ハイテク 走査電子顕微鏡及び２次電子スピン偏極度を解析する方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60177539A (ja) * 1984-02-24 1985-09-11 Hitachi Ltd 走査型電子顕微鏡
JPS6273185A (ja) * 1985-09-27 1987-04-03 Hitachi Ltd スピン検出器
JPH10188883A (ja) * 1996-12-26 1998-07-21 Shimadzu Corp エネルギーアナライザー
JP2006261111A (ja) * 2005-03-17 2006-09-28 Ict Integrated Circuit Testing Ges Fuer Halbleiterprueftechnik Mbh 分析システムおよび荷電粒子ビームデバイス
JP2010146968A (ja) * 2008-12-22 2010-07-01 Hitachi Ltd 電子スピン検出器並びにそれを用いたスピン偏極走査電子顕微鏡及びスピン分解光電子分光装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60177539A (ja) * 1984-02-24 1985-09-11 Hitachi Ltd 走査型電子顕微鏡
JPS6273185A (ja) * 1985-09-27 1987-04-03 Hitachi Ltd スピン検出器
JPH10188883A (ja) * 1996-12-26 1998-07-21 Shimadzu Corp エネルギーアナライザー
JP2006261111A (ja) * 2005-03-17 2006-09-28 Ict Integrated Circuit Testing Ges Fuer Halbleiterprueftechnik Mbh 分析システムおよび荷電粒子ビームデバイス
JP2010146968A (ja) * 2008-12-22 2010-07-01 Hitachi Ltd 電子スピン検出器並びにそれを用いたスピン偏極走査電子顕微鏡及びスピン分解光電子分光装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPWO2019186736A1 (ja) * 2018-03-27 2021-02-12 株式会社日立ハイテク 走査電子顕微鏡及び２次電子スピン偏極度を解析する方法
WO2019224919A1 (fr) * 2018-05-22 2019-11-28 株式会社日立ハイテクノロジーズ Dispositif d'analyse de spin
JPWO2019224919A1 (ja) * 2018-05-22 2021-05-13 株式会社日立ハイテク スピン分析装置

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JPWO2015029201A1 (ja) 2017-03-02

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