JP5553308B2 - Light element analyzer and analysis method - Google Patents

Description

  The present invention relates to a method and apparatus for analyzing light elements such as hydrogen and lithium existing near the surface of a sample.

  Secondary ion mass spectrometry (SIMS: 1277686212564_0) and electron excited ion desorption (ESD) are known as methods for analyzing the concentration of light elements on the material surface. In SIMS, an ion beam having an energy of several hundred eV to several tens of thousands eV is incident on a sample (material). Then, some of the sample atoms that have received the energy jump out. This is called sputtering. In sputtering, ions incident on the sample surface give momentum to sample constituent atoms by elastic collision, and the atoms given momentum recoil and repeat collisions with neighboring atoms one after another. As a result, SIMS is a method for mass spectrometry of secondary ions released from a sample. When the secondary particles are neutral particles, they may be ionized by laser irradiation or the like. ESD is a method in which an electron beam is incident on a sample, and ions emitted from the sample are analyzed in time of flight. Patent Document 1 describes a method of analyzing hydrogen present on a sample surface by causing an electron beam to enter the sample and analyzing ions emitted from the sample by a time-of-flight analysis method. Non-Patent Documents 1 and 2 report that light elements are desorbed by stimulation with metastable helium atoms or multivalent ions.

Japanese Patent Laid-Open No. 10-269983

M. Kurahashi, Y. Yamauchi, Phys. Rev. Lett., 84, (2000) 4725. K. Kuroki, N. Okabayashi, H. Torii, K. Komaki, Y. Yamazaki, Appl. Phys. Lett., 81, (2002) 3561.

  SIMS is an analysis method in which ions, atoms, and clusters are struck against a sample surface to scrape the surface, or a surface material is splashed off, and analysis is performed while destroying the sample surface. At present, both the electron beam and the ion beam can be converged to nanometers or less, but the electron beam scatters more on the sample surface than the ion beam, and discharges hydrogen in a wide area. The spatial resolution is inferior to that using an ion beam. When an insulating material is analyzed using an electron beam, a problem of charge up of the sample also occurs. In addition, since incident metastable helium atoms and incident multiply charged ions are difficult to converge, it is difficult to increase the spatial resolution.

  An object of the present invention is to provide a method and apparatus for measuring and visualizing the in-plane distribution of light elements existing near the surface of a sample with non-destructive and high spatial resolution.

  In the present invention, an ion beam is intermittently incident on a sample, and ions / particles emitted from the sample are detected in synchronization with the incidence, that is, a light element (especially a light element present on the sample surface) is analyzed. Analysis of hydrogen and lithium. Also, by mapping the analysis results at each point on the sample surface, the spatial distribution of the element of interest on the sample surface can be visualized and displayed.

  According to the present invention, light elements such as hydrogen and lithium existing near the surface of the sample can be analyzed and the spatial distribution can be visualized with high spatial resolution and without subjecting the sample to thin film processing.

The conceptual diagram which shows the example of whole structure of the light element analysis microscope apparatus by the ion beam stimulation desorption of this invention. Schematic which shows an example of a time analysis circuit. Explanatory drawing which shows arrangement | positioning and electric potential distribution of the grid between a sample and a time-of-flight analysis detector. The figure which shows the example which analyzed the MgLi alloy by ion beam stimulation desorption. The figure which shows the sample electric potential dependence of flight time. The enlarged view of the vertical axis | shaft of FIG. The figure which shows the sample potential dependence of the flight time with respect to the monovalent ion of a light element.

  The present invention proposes a light element analysis method by ion beam stimulated desorption, and is an analysis method based on experimental results that have not been discovered so far. In addition, in this specification, a light element refers to an element lighter than Na element. In the prior art, an electron beam is incident on a sample, but the present invention is decisively different from the prior art in that an ion beam is incident on a sample and light elements are analyzed. Compared to the case of using an electron beam by using an ion beam, it is possible to achieve a microscopic method that can analyze the concentration distribution of light elements with higher spatial resolution because the region from which light elements are emitted can ultimately be made smaller. . When the sample is irradiated with an electron beam, the electrons in the beam are quickly scattered in the sample and interact with the sample in a region much wider than the beam diameter. Therefore, the spatial resolution is deteriorated. On the other hand, when the sample is irradiated with an ion beam, since ions are heavier than electrons, there is little scattering near the surface of the sample. Therefore, the region where ions interact is narrowed, and high spatial resolution is obtained. As a result, it is possible to achieve a spatial resolution of 10 times or more compared with the analysis method using an electron beam.

The mechanism of ion beam stimulated desorption is as follows. The mechanism of ion beam stimulated desorption is considered to be basically due to desorption induced by electronic transition (DIET). In other words, when the ion beam is incident on the sample, electrons near the sample surface are excited, and when the excited electrons deviate from the binding orbit, repulsion occurs between the atoms emitted as ions and the material atoms, and desorption Happens. In particular,
(1) Electron excitation occurs due to collision between the ion beam and electrons (2) Electron stimulated desorption (ESD) occurs due to secondary electrons generated due to collision between the ion beam and electrons (3) Charge conversion of the ion beam occurs It is thought that DIET causes.

On the other hand, with electron stimulated desorption (ESD), (a) atoms in a sample are ionized (electrons in the sample are excited) by electron stimulation, and the ions are desorbed. Alternatively, it returns to the ground state again in the process of desorption, and when there is surplus energy at that time, it is desorbed as neutral particles. (B) Electrons in the inner orbitals of atoms in the substance are excited by electron stimulation ( This is a phenomenon that is thought to be eliminated by an interatomic Auge transition where electrons of the emitted material fall into the hole.

  That is, the ion beam stimulated desorption mechanism is different from that in which the ion beam directly transfers energy to the sample atom as in secondary ion mass spectrometry (SIMS).

  Further, by using an ion beam as an incident beam, it is possible to analyze light elements while analyzing scattered particles from a sample in parallel. That is, the composition of the sample can be known in parallel with the spatial distribution of light elements. Thereby, the correlation between the concentration of the light element and the sample composition can be known. Furthermore, an insulator can be analyzed by using an ion beam and performing time-of-flight analysis. This is because even when the insulator sample is charged up, the ion beam is heavier than the electron beam, so there is less blurring, and in the time-of-flight analysis, the entire measurement time region is always measured, so desorption ions are caused by charge-up. Even if is accelerated, it can be measured without any problem.

The incident ions need not be multivalent ions. As the incident ions, monovalent He ⁺ ions, Ga ⁺ ions, or the like can be used. Ga can also be used as incident ions. However, when heavy ions such as Ga are used as incident ions, scattering information can be obtained only from atoms heavier than Ga.

  The incident energy of the ion beam is preferably in the range of 1 keV to 500 keV. Regarding scattering information, a low energy ion beam may be incident to obtain information on the very surface of the sample, and a high energy ion beam may be incident to obtain information on a deep region from the surface. For example, when it is desired to analyze a depth region of about 1 nm from the surface, the incident energy is set to about 1 keV, and when it is desired to analyze a depth region from the surface to about 50 nm, the incident energy is set to about 100 keV. As for ion beam stimulated desorption information, ions are desorbed only from the surface.

  The beam current as a continuous beam (the average beam current in the case of a pulse beam) is preferably 0.01 pA to 100 nA. The ion beam is preferably incident on the sample as a pulse beam, and the pulse width of the pulse ion beam is preferably 1 ns or more and 500 ns or less. The pulse of the ion beam may be such that the desorbed ions have the best S / N according to the length of the flight path from the sample to the time analysis type detector. However, in the case of an ion beam, it is difficult to generate a pulse beam of 1 ns or less.

  It is necessary to consider the pulse repetition frequency of the pulse ion beam so that the desorption ion signal does not overlap with the desorption ion signal caused by the previous pulse ion beam. For example, when the distance from the sample to the detector is 250 mm, the repetition frequency needs to be 100 kHz or less.

The analysis method of the present invention is a non-destructive analysis. This is because the mechanism of this analysis is DIET, i.e. by inelastic collisions. Actually, the measurement is possible by the incidence of ions of about 1.875 × 10 ¹² [ions / cm ² ] as in the following equation.

here,
Continuous ion beam intensity: 50 [nA]
Elementary charge: 1.60 × 10 ^-19 [C]
Pulse ion beam repetition: 50 [kHz]
Pulse width of pulsed ion beam: 2 [ns]
Measurement time: 300 [s]
Measurement area: 0.05cm x 0.1cm

  A microchannel plate can be used as a particle detector for time-of-flight analysis. When a microchannel plate and a wire anode are used in combination, the light element binding direction on the sample surface can be known and the S / N ratio may be increased, but the use of a wire anode is not essential. .

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram showing an example of the overall configuration of a light element analysis microscope apparatus using ion beam stimulated desorption according to the present invention.

  The sample 10 is held in a sample holder 17 and installed in a vacuum chamber 12 that is evacuated by an exhaust device 11. The apparatus includes a scanning focused pulse ion beam source 13, a time-of-flight analysis detector 14, and a calculation / display unit 15. The time-of-flight analysis detector 14 can be, for example, a position sensitive and time-resolved microchannel plate detector with a wire anode. The calculation / display unit 15 has a function as a time analyzer and can be realized by a personal computer. The time analyzer uses a signal picked up from the scanning focused pulsed ion beam source 13 as a start signal, and light element ions such as scattered particles and hydrogen generated from the sample 10 by the incidence of the pulsed ion beam are detected by the time of flight analysis detector. The signal that appears at the anode after entering 14 is used as a stop signal, and the time difference between the time when the start signal appears and the time when the stop signal appears is analyzed to detect scattered particles and light element ions.

  Note that instead of a pulse ion beam source, a scanning focused ion beam source can be used as the ion beam source. In that case, a secondary electron detector 16 or the like is installed near the sample 10, and secondary electrons emitted from the sample when the ion beam is incident on the sample are detected by the secondary electron detector 16. A signal picked up from the secondary electron detector 16 is used as a start signal.

  FIG. 2 is a schematic diagram illustrating an example of a time analysis circuit. This circuit diagram is an example of a circuit used when a two-dimensional position sensitive / time analysis type microchannel detector having a wire anode is used. Soft X-rays, scattered particles, and ions emitted by ion beam stimulated desorption enter a microchannel plate (MCP) 20 and are converted into secondary electrons. Secondary electrons are multiplied to the amount of charge that can be read in the MCP. The electric charge is drawn into the wire anode 21, and the electric charge further moves toward the four anode ends A to D. Since a voltage is applied to the anode in order to draw an electric charge, the anode ends A to D are coupled so as not to pass a direct current by a capacitor. The signal appearing through the coupling capacitor 22 is amplified by a differential amplifier (or pulse transformer) 23 and input to a CFD (Constant Discriminator) circuit 24 that can know when the signal arrives at the anode end. . The CFD circuit 24 is for preventing jitter in the signal arrival time due to the difference in signal height. The timing at which signals arrive at the four ends A to D is created by the CFD circuit 24, and the signal is used as a stop signal for a TDC (Time to Digital Converter) 25.

  A signal output at the timing when the beam chopping high-voltage pulse generator 26 generates a pulse beam is used as a start signal of the TDC 25. Furthermore, in the MCP 20, when soft X-rays, scattered particles, and ions emitted by ion beam stimulated desorption enter the MCP, the voltage applied to the MCP fluctuates, so that a current flows on the back surface of the MCP. . Coincident with this event and measure. The time (position) information measured by the TDC 25 is calculated by the personal computer 27 and displayed on the display.

Anode end A and anode end B, anode end C and anode end D are paired. When the time from when the start signal is generated until the signal due to particle incidence is detected at the anode ends A to _D is T _{A to} T _D , the flight time t of the particle is calculated as follows. .

t = (T _A + T _B ) / 2, or
t = (T _C + T _D ) / 2

  FIG. 3 is an explanatory diagram showing the grid arrangement and potential distribution between the sample and the time-of-flight analysis detector. Between the sample 10 and the MCP 20 of the time-of-flight analysis detector, a pair of grids including a sample-side grid 31 arranged near the sample and a detector-side grid 32 arranged close to the detector are installed. ing. Both the sample-side grid 31 and the detector-side grid 32 are grounded to the ground, and the space between them is field-free. In addition, a voltage is applied to the sample 10 from the DC power source 33 to make it positive with respect to the ground. The MCP 20 is applied with a voltage from the DC power supply 34 and is at a negative potential with respect to the ground. Accordingly, the desorbed ions 42 having positive charges desorbed from the sample 10 by irradiation with the pulsed ion beam 41 are accelerated in the acceleration field between the sample 10 and the sample side grid 31, and then the sample side grid 31 and the detector. It moves at a constant speed between the side grids 32, and finally is accelerated again in the acceleration field between the detector side grid 32 and the MCP 20 and enters the MCP 20.

The flight time from the sample 10 to the sample side grid 31 is t ₁ , the flight time from the sample side grid 31 to the detector side grid 32 is t ₂ , and the flight time from the detector side grid 32 to the detector surface, that is, the MCP 20 is t. _{Assuming 3} , the total flight time t is t ₁ + t ₂ + t ₃ . Here, the mass of the ion 42 desorbed by ion beam stimulated desorption is m, the kinetic energy at the time of desorption of the desorbed ion is E _k , the charge of the desorbed ion is q (= n · e), and n is valence. Number, e is the elementary electron content, sample potential is V _s , the distance between the sample 10 and the sample side grid 31 is L ₁ , the distance between the sample side grid 31 and the detector side grid 32 is L ₂ , and the detector side grid 32 a detector (MCP20) the distance between the surface L _3, when the potential of the detector (MCP20) surface and V _MCP, the flight time t _1, t _2, t _3, respectively as follows.

Accordingly, the total flight time t is t = t ₁ + t ₂ + t ₃ , but L ₃ is smaller than L ₁ + L ₂ and _VMCP is sufficiently small (the absolute value of _VMCP is sufficiently large). In this case, the total flight time t can be approximately t≈t ₁ + t ₂ .

  When the pulsed ion beam is not forcibly generated, the secondary electron detector 16 can be used to detect that the ion beam 41 has entered the sample 10. Accordingly, the time of flight may be measured using the signal generated from the secondary electron detector 16 as a start signal. For example, when the ion beam is reduced in intensity, intermittent ion flow occurs without forcibly creating a pulsed ion beam. For example, if it is 0.1 pA of monovalent ions,

となる。言い換えれば、１．６μｓに１個のパルスビームに相当する。

It becomes. In other words, it corresponds to one pulse beam per 1.6 μs.

MgLi alloy samples were measured using the apparatus of the present invention described with reference to FIGS. As a sample, an MgLi alloy having a size of 10 mm × 10 mm was placed in a vacuum chamber evacuated to 10 ⁻⁹ Torr or less. The distance from the sample 10 to the sample side grid 31 close to the sample is 0.025 [m], the distance between the sample side grid 31 and the detector side grid 32 close to the MCP 20 is 0.23 [m], and the detector side grid The distance from 32 to MCP20 was 0.01 [m]. By setting these potentials and distances, the flight time of desorbed ions desorbed from the sample can be changed. Thereby, the arrival time of desorbed ions can be changed in a good S / N state. Alternatively, it can arrive within the TDC measurement range.

As the pulsed ion beam 41, a He ⁺ ion beam was used. The scanning focused pulse ion beam source 13 generates a pulse ion beam 41 having a repetition frequency of 50 [kHz] and a pulse width of 2 [ns] from a continuous ion beam obtained by accelerating He ⁺ ions to 100 [keV] by a beam deflection method. To do. That is, one side electrode of a parallel plate chopper is grounded, connected to a high voltage pulse generator pulser that generates a deflection electric field on the other electrode, a high voltage pulse is applied, a continuous ion beam is periodically deflected, The pulsed ion beam 41 is generated by cutting out the continuous ion beam by the chopping aperture at (1). The generated pulsed ion beam 41 was incident on the sample 10. The average beam current of the He ⁺ ion beam is 0.1 pA, and the beam diameter is 0.5 mm × 1 mm.

  Measurement was performed while changing the sample potential to 100 [V], 200 [V], 300 [V], 400 [V], and 500 [V]. The vacuum chamber 12 is grounded, and the potential is the potential from the vacuum chamber 12. The pair of grids 31 and 32 are also grounded. The MCP 20 was a three-sheet set, and the measurement was performed with the MCP surface potential (MCP front potential) set to -3000 [V] (from ground potential).

The measurement results are shown in FIG. By applying the flight time to the above approximate expression t≈t ₁ + t ₂ , the mass m of ions desorbed by stimulated desorption, the charge q (= n · e) of desorbed ions, and the desorption of desorbed ions The kinetic energy E _{k of} was calculated. Since there are three unknowns, if the measurement is performed three or more times by changing the sample potential, the ion mass m, that is, the ion species, the charge e of the desorbed ions, and the kinetic energy E _k at the time of desorption are _obtained . be able to. As a result, m = 1.008 [u] hydrogen ion H ⁺ and m = 7.016 [u] lithium ion Li ⁺ were detected by ion beam stimulated desorption.

In FIG. 5, theoretical calculation values are plotted with solid lines, and experimental values are plotted with white circles. It can be seen that the sample potential dependence of the flight time of each ion is in good agreement with the measured value and theoretical calculation. In the theoretical calculation, the kinetic energy E _k at the time of desorption of hydrogen ion H ⁺ and lithium ion Li ⁺ was calculated as 18 [eV] and 16 [eV], respectively.

If you only want to identify the ion species to be released by ion beam stimulated desorption,
q ・ V _s ≫E _k
Therefore, the sample potential V _s may be set to a relatively high potential, for example, several kV. In that case, E _k can be ignored in the above-mentioned relational expression t = t ₁ + t ₂ + t ₃ of flight time. The charge of separated ionic species and desorbed ions can be identified. Also at this time, if L ₃ is smaller than L ₁ + L ₂ and _VMCP is sufficiently small (the absolute value of _VMCP is sufficiently large), the total flight time t is approximately t≈t _1. + T ₂ .

In order to obtain E _k , measurement may be performed at a different sample potential of a relatively low sample potential V _s , for example, 100 [V] or less. It is considered that the hydrogen detected in this experiment was adsorbed on the sample surface. Further, the detected lithium ions are emitted from lithium existing in the vicinity of the surface and correspond to the concentration of lithium in the vicinity of the surface.

  The ionic species can be identified by the above operation. The flight time basically starts with a signal extracted from a pulse beam generation pulser, but it uses pulsed ions by utilizing the fact that soft X-rays (light) are emitted when the ion beam enters the sample. It is also possible to calculate the flight time from the timing when the beam arrives at the sample. Since MCP is sensitive to soft X-rays, soft X-rays can also be measured by using a time analysis detector using MCP.

Note that the spectrum shown in FIG. 4 is a measurement result at one point on the sample. By performing the same measurement at each point on the sample by scanning the incident ion beam on the sample, hydrogen and It is possible to measure the two-dimensional spatial distribution of light elements such as lithium, and to visualize the measured spatial distribution by performing known appropriate processing such as color coding according to the concentration and displaying it on the calculation / display unit 15 Can do. At present, the He ⁺ ion beam can be narrowed down to about 0.35 nm. When an ion beam with a beam diameter of 0.35 nm is used, the spatial distribution of light elements can be measured with a spatial resolution of 1 nm or less. Is possible.

  Here, if the measurement conditions such as the sample potential and the surface potential of the detector are the same, the peak of the light element of interest appears at the same flight time position in the flight time spectrum. Therefore, if the correspondence between the peak of the time-of-flight spectrum and the light element is first obtained using the above calculation formula, by focusing on the specific time-of-flight peak appearing in the time-of-flight spectrum from the next measurement, Information on the presence or concentration of the light element of interest can be obtained immediately.

  In ion beam stimulated desorption, three-dimensional (time-of-flight analysis type) medium-energy ion scattering spectroscopy spectra can be obtained in parallel, enabling elemental analysis.

  FIG. 6 is an enlarged view of the vertical axis of FIG.

Information on the composition of the analysis region can be obtained from the time of flight and the scattering yield of the scattered particles from the component. The energy of the He particles scattered by the surface Mg atoms and scattered to a scattering angle of 140 ° is 55.56 keV. The velocity of the He particles with that energy is 1.637 × 10 ⁸ [cm / s]. When the flight path is 25.5 [cm], the flight time is 155.8 [ns]. Moreover, what is scattered inside the sample is detected after 1 to 2 μs. When the E _k of hydrogen ion and lithium ion is 18 [eV] and 16 [eV], respectively, the sample potential is 100 [V], and L ₁ and L ₂ are 2.5 cm and 23 cm, respectively, As can be seen from FIG. 5, the flight times of H ⁺ and lithium ion Li ⁺ are 1764 ns and 4700 ns, respectively.

FIG. 7 is a diagram of a theoretical curve showing the sample potential dependence of flight time calculated for monovalent ions of light elements from H-1 to Na-23. E _k was calculated as 18 eV for H ^{+ and} 16 eV for Li ^{+ to} Na ⁺ . The experimental results are plotted for H ⁺ and Li ⁺ . By utilizing such a relationship between the flight time and the sample potential, it is possible to identify light elements existing on the sample surface and obtain the concentration distribution of light elements other than hydrogen and lithium.

DESCRIPTION OF SYMBOLS 10 Sample 11 Exhaust apparatus 12 Vacuum chamber 13 Scanning focused pulse ion beam source 14 Time analysis type detector 15 Calculation / display part 17 Sample holder 16 Secondary electron detector 20 MCP
21 Wire anode 22 Coupling capacitor 23 Differential amplifier 24 CFD circuit 25 TDC
26 High-voltage pulse generator for beam chopping 27 Personal computer 31 Sample-side grid 32 Detector-side grids 33 and 34 DC power supply 41 Pulse ion beam 42 Desorption ion

Claims (10)

A sample holder installed in an evacuated vacuum chamber;
A first power source for applying a voltage to the sample held in the sample holder;
An ion beam source that irradiates a sample held by the sample holder with a He ⁺ ion beam as a pulsed ion beam at an incident energy in the range of 1 keV to 500 keV ;
A particle detector;
A second power source for applying a voltage to the particle detector;
A first grid disposed between the sample holder and the particle detector and in the vicinity of the sample holder and grounded;
A second grid disposed between the sample holder and the particle detector, in proximity to the particle detector and grounded;
A calculation unit that measures the flight time t of ions released by ion beam stimulated desorption from the sample held in the sample holder by the incidence of the pulsed ion beam, and identifies the ion species;
The calculation unit is configured such that the mass of the ion is m, the kinetic energy of the ion when the sample is desorbed is E _k , the charge of the ion is q, the potential of the sample is V _s , and the distance between the sample and the first grid L ₁ , the distance between the first grid and the second grid is L ₂ , the distance between the second grid and the surface of the particle detector is L ₃ , and the surface potential of the particle detector is An elemental analyzer characterized by identifying the ion species using a relationship of t = t ₁ + t ₂ + t ₃ when V _MCP is used.

  2. The elemental analyzer according to claim 1, wherein the particle detector is a microchannel plate.   The elemental analysis apparatus according to claim 1, wherein the calculation unit identifies hydrogen ions or lithium ions released from a sample.   2. The element analyzer according to claim 1, wherein the ion beam source is a scanning ion beam source. The elemental analyzer according to claim 4, wherein
Having a display,
Before SL calculation unit identified released hydrogen ions or lithium ions from a sample,
An elemental analyzer that displays a spatial distribution of hydrogen atoms or lithium atoms on a sample surface on the display unit. Intermittently irradiating a sample held in vacuum with a He ⁺ ion beam with an incident energy in the range of 1 keV to 500 keV ;
Performing time-of-flight analysis of ions or particles released from the sample by ion beam stimulated desorption,
An elemental analysis method characterized by analyzing a light element existing on a sample surface. The elemental analysis method according to claim 6,
Between the sample and the particle detector, a grid arranged near the sample and grounded is defined as a first grid, and a grid disposed near the particle detector and grounded is defined as a second grid. The mass is m, the kinetic energy at the time of sample desorption of the ions or particles is E _k , the charge of the ions or particles is q, the potential of the sample is V _s , and the distance between the sample and the first grid is L ₁ , The distance between the first grid and the second grid is L ₂ , the distance between the second grid and the surface of the particle detector is L ₃ , and the potential of the surface of the particle detector is _VMCP . When
Change the sample potential V _s and perform multiple measurements,
An elemental analysis method characterized by identifying the ion species or particle species using a relationship of t = t ₁ + t ₂ + t ₃ , where t is a measured flight time.

The elemental analysis method according to claim 6,
Between the sample and the particle detector, a grid arranged near the sample and grounded is defined as a first grid, and a grid disposed near the particle detector and grounded is defined as a second grid. The mass is m, the ion or particle charge is q, the sample potential is V _s , the distance between the sample and the first grid is L ₁ , and the distance between the first grid and the second grid is L _{2. When} the distance between the second grid and the surface of the particle detector is L ₃ , and the potential of the surface of the particle detector is _VMCP ,
The potential V _s of the sample is set to a value such that the kinetic energy at the time of sample desorption of the ions or particles can be ignored compared to q · V _s ,
An elemental analysis method characterized by identifying the ion species or particle species using a relationship of t = t ₁ + t ₂ + t ₃ , where t is a measured flight time.

In the elemental analysis method according to any one of claims 6 to 8,
An elemental analysis method comprising: scanning the ion beam to analyze a light element at a plurality of positions on a sample surface, and displaying a distribution of the detected light element on the sample surface.   The elemental analysis method according to claim 6, wherein the light element is hydrogen or lithium.

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