Projection-type charged particle optical system and imaging mass spectrometry apparatus

Patent metadata

Field	Value
Publication number	US-9570276-B2
Application number	US-201514901672-A
Country	US
Kind code	B2
Filing date	Feb 26, 2015
Priority date	Mar 3, 2014
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

Provided is a projection-type charged particle optical system in which a projection magnification can be changed while a decrease in the accuracy in measuring a mass-to-charge ratio is being suppressed. A projection-type charged particle optical system according to the present invention includes a first electrode disposed so as to face a sample and having an opening formed therein for allowing a charged particle to pass, a second electrode disposed on a side of the first electrode opposite to where the sample is disposed and having an opening formed therein for allowing the charged particle to pass, and a flight-tube electrode disposed such that the charged particle that has been emitted from the sample and has passed through the second electrode enters the flight-tube electrode and being configured to form a substantially equipotential space thereinside. A principal plane is formed at at least two positions in a travel path of the charged particle.

First claim

The invention claimed is:

1. A projection-type charged particle optical system, comprising:
a first electrode disposed so as to face a sample, the first electrode having an opening formed therein for allowing a charged particle to pass therethrough;
a second electrode disposed on a side of the first electrode, the side being opposite to where the sample is disposed, the second electrode having an opening formed therein for allowing the charged particle to pass therethrough; and
a flight-tube electrode disposed such that the charged particle that has been emitted from the sample and has passed through the first and second electrodes enters the flight-tube electrode, the flight-tube electrode being configured to form a substantially equipotential space thereinside,
wherein a principal plane is formed at at least two positions in a travel path of the charged particle.

2. The projection-type charged particle optical system according to claim 1 , wherein at least one of the first and second electrodes is a hollow cone, the opening being located at a vertex of the hollow cone.

3. The projection-type charged particle optical system according to claim 1 , wherein a distance from the sample to any of the first and second electrodes and the flight-tube electrode is variable.

4. The projection-type charged particle optical system according to claim 1 , wherein a potential difference between the first and second electrodes is smaller than a potential difference between the sample and the first electrode.

5. The projection-type charged particle optical system according to claim 1 , further comprising:
a third electrode disposed between the second electrode and the flight-tube electrode, the third electrode having an opening formed therein for allowing the charged particle to pass therethrough.

6. The projection-type charged particle optical system according to claim 5 , wherein the projection-type charged particle optical system is provided with a first operation mode in which the potential difference between the first and second electrodes is smaller than a potential difference between the second and third electrodes, and a second operation mode in which the potential difference between the second and third electrodes is smaller than the potential difference between the first and second electrodes.

7. The projection-type charged particle optical system according to claim 5 , further comprising:
a fourth electrode disposed between the third electrode and the flight-tube electrode, the fourth electrode having an opening formed therein for allowing the charged particle to pass therethrough.

8. The projection-type charged particle optical system according to claim 7 , further comprising:
a fifth electrode disposed between the fourth electrode and the flight-tube electrode, the fifth electrode having an opening formed therein for allowing the charged particle to pass therethrough.

9. The projection-type charged particle optical system according to claim 1 , wherein the flight-tube electrode includes a planar member provided at an end thereof, the planar member having an opening formed therein for allowing the charged particle to pass therethrough.

10. A time-of-flight mass spectrometer, comprising:
the projection-type charged particle optical system according to claim 1 ; and
a position- and time-sensitive detector configured to detect the charged particle that has passed through the flight-tube electrode,
wherein an image of the charged particle is formed on a surface of the position- and time-sensitive detector, and a time at which the charged particle has been detected is recorded in the position- and time-sensitive detector.

11. The time-of-flight mass spectrometer according to claim 10 , wherein a potential difference is generated between a detection surface of the position- and time-sensitive detector on which the charged particle is incident and the flight-tube electrode such that kinetic energy of the charged particle increases.

12. A time-of-flight mass spectrometry apparatus, comprising:
the time-of-flight mass spectrometer according to claim 10 ; and
a pulsed charged particle source configured to generate charged particles from a surface of the sample in pulses.

13. The time-of-flight mass spectrometry apparatus according to claim 12 , wherein the pulsed charged particle source is an ion beam.

14. The time-of-flight mass spectrometry apparatus according to claim 13 , wherein the ion beam is a cluster ion beam.

15. The time-of-flight mass spectrometry apparatus according to claim 12 , wherein the pulsed charged particle source is an electromagnetic wave.

16. The time-of-flight mass spectrometry apparatus according to claim 12 , wherein a size of a region on the surface of the sample from which the charged particles are caused to be emitted by the pulsed charged particle source is equal to or greater than a size of the opening formed in the first electrode.

17. A method for projecting a charged particle with a projection-type charged particle optical system that includes a first electrode disposed so as to face a sample and having an opening formed therein for allowing the charged particle to pass therethrough, a second electrode disposed on a side of the first electrode that is opposite to where the sample is disposed and having an opening formed therein for allowing the charged particle to pass therethrough, and a flight-tube electrode disposed such that the charged particle that has been emitted from the sample and has passed through the first and second electrodes enters the flight-tube electrode and being configured to form a substantially equipotential space thereinside, the method comprising;
forming a principal plane at a first position in a travel path of the charged particle; and
forming the principal plane at a second position in the travel path of the charged particle, the second position being different from the first position.

18. The method for projecting a charged particle according to claim 17 , wherein a third electrode is further disposed between the second electrode and the flight-tube electrode, the third electrode having an opening formed therein for allowing the charged particle to pass therethrough, and
wherein a position at which the principal plane is formed is changed by changing a potential of each of the first, second, and third electrodes.

19. The method for projecting a charged particle according to claim 18 , wherein a fourth electrode is further disposed between the third electrode and the flight-tube electrode, the fourth electrode having an opening formed therein for allowing the charged particle to pass therethrough, and
wherein the position at which the principal plane is formed is changed by changing a potential of each of the first, second, third, and fourth electrodes.

20. The method for projecting a charged particle according to claim 19 , wherein a fifth electrode is further disposed between the fourth electrode and the flight-tube electrode, the fifth electrode having an opening formed therein for allowing the charged particle to pass therethrough, and
wherein the position at which the principal plane is formed is changed by changing a potential of each of the first, second, third, fourth, and fifth electrodes.

Assignees

• Canon Kk

Inventors

• Iwasaki Kota

Classifications

• H01J49/067

  Ion lenses, apertures, skimmers · CPC title

• H01J49/10

  Ion sources; Ion guns · CPC title

• H01J37/252

  Tubes for spot-analysing by electron or ion beams; Microanalysers · CPC title

• H01J49/40

  Time-of-flight spectrometers (H01J49/36 takes precedence) · CPC title

• H01J49/164 Primary

  Laser desorption/ionisation, e.g. matrix-assisted laser desorption/ionisation [MALDI] (sample holders H01J49/0418) · CPC title