Mass spectrometer, use thereof, and method for the mass spectrometric examination of a gas mixture

Patent metadata

Field	Value
Publication number	US-10304672-B2
Application number	US-201514967699-A
Country	US
Kind code	B2
Filing date	Dec 14, 2015
Priority date	Jul 10, 2013
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

The disclosure relates to a mass spectrometer for mass spectrometric examination of gas mixtures, including: an ionization device and an ion trap for storage and mass spectrometric examination of the gas mixture. In one aspect of the disclosure, the ionization device is embodied for supplying ions and/or metastable particles of an ionization gas and/or for supplying electrons to the ion trap for ionizing the gas mixture to be examined and the mass spectrometer is embodied to determine the number of ions and/or metastable particles of the ionization gas present in the ion trap and/or the number of ions of a residual gas present in the ion trap prior to examining the gas mixture. The disclosure also relates to the use of such a mass spectrometer and a method for mass spectrometric examination of a gas mixture.

First claim

What is claimed is:

1. A mass spectrometer, comprising:
an ionization device configured to provide an ionization component which comprises at least one member selected from the group consisting of: a) ions of an ionization gas; and b) metastable particles of the ionization gas;
an ion trap configured to store and mass spectrometrically examine a gas mixture in the ion trap; and
a controllable inlet configured to provide a pulsed supply of the gas mixture to the ion trap,
wherein the mass spectrometer is configured so that, during use of the mass spectrometer:
the ionization device provides the ionization component to the ion trap and the controllable inlet provides the pulsed gas supply to the ion trap so that the ionization component ionizes the gas mixture in the ion trap via a charge exchange process and/or impact ionization;
determines a number of a substance which comprises at least one member selected from the group consisting of: a) ions of the ionization gas present in the ion trap; b) metastable particles of the ionization gas present in the ion trap; and c) ions of a residual gas present in the ion trap prior to examining the gas mixture; and
reduces an influence of fluctuations of the ionization component by determining a particle number of ionized constituents of the gas mixture in the ion trap in a pulsed manner using a correction factor that takes into account the determined number of the substance.

2. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to determine a particle number of an ionized constituent of the gas mixture in the ion trap with an inaccuracy of less than 5%.

3. The mass spectrometer of claim 1 , wherein the ionization device is configured to supply metastable particles of an ionization gas in the form of a metastable noble gas.

4. The mass spectrometer of claim 3 , wherein the mass spectrometer is configured to record at least 10 spectra per second with a mass bandwidth of 500 atomic mass units in each case.

5. The mass spectrometer of claim 1 , further comprising a plasma source configured to produce the ionization component.

6. The mass spectrometer of claim 5 , wherein the plasma source is configured to produce the ionization component at a temperature of less than 100° C.

7. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured so that, when a number of ionized constituents of the gas mixture present in the ion trap exceeds a threshold, the mass spectrometer removes at least some of the of ionized constituents from the ion trap.

8. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to selectively detect ionized constituents of the gas mixture in predefined measurement ranges of mass-to-charge ratio.

9. The mass spectrometer of claim 1 , wherein the mass spectrometer has a dynamic range of 10 8 or more.

10. The mass spectrometer of claim 1 , wherein the ion trap is configured to accumulate individual ionized gas constituents of the gas mixture, and the mass spectrometer has a detection limit of 10 −15 millibar or less.

11. The mass spectrometer of claim 1 , further comprising a pressure reduction unit which comprises at least one modular pressure stages configured to be connected in series to reduce the gas pressure of the gas mixture.

12. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to examine gas mixtures with a gas pressure of between 10 5 millibar and 10 −15 millibar.

13. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to: a) repeatedly excite ionized constituents of the gas mixture in the ion trap; and b) record a mass spectrum of the ionized constituents to be examined during a predetermined time duration of each excitation.

14. The mass spectrometer of claim 13 , wherein the time duration for recording a mass spectrum is five milliseconds or less.

15. The mass spectrometer of claim 1 , wherein the ion trap comprises a member selected from the group consisting of a Fourier transform ion trap, a Penning trap, a toroidal trap, a Paul trap, a linear trap, an orbitrap, an EBIT, and a nRF buncher.

16. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to detect vibrations with a vibration frequency of between 1 Hz and 15 kHz.

17. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to determine a number of ions present in the ion trap.

18. The mass spectrometer of claim 17 , wherein the mass spectrometer is configured to determine a particle number of ionized constituents of the gas mixture in the ion trap, taking into account the determined number of ions present in the ion trap.

19. The mass spectrometer of claim 1 , wherein:
the ionization component comprises metastable particles of the ionization gas; and
the mass spectrometer is configured to determine a number of the metastable particles of the ionization gas present in the ion trap.

20. The mass spectrometer of claim 19 , wherein the mass spectrometer is configured to determine a particle number of ionized constituents of the gas mixture in the ion trap, taking into account the determined number of metastable particles of the ionization gas present in the ion trap.

21. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured so that, during use of the mass spectrometer:
an increase in the determined particle number results in a decrease in the correction factor; and
a decrease in the determined particle number results in an increase in the correction factor.

22. The mass spectrometer of claim 1 , wherein the mass spectrometer is configured to:
supply to the ion trap metastable particles of the ionization gas;
determine the number of i) metastable particles of the ionization gas present in the ion trap; and ii) ions of a residual gas present in the ion trap prior to examining the gas mixture; and
reduce the influence of fluctuations of the ions or metastable particles provided for the ionization by determining a particle number of ionized constituents of the gas mixture in the ion trap in a pulsed manner using a correction factor that takes into account the determined number of at least one member selected from the group consisting of: i) metastable particles of the ionization gas; and ii) ions of the residual gas.

23. The mass spectrometer of claim 22 , wherein the metastable particles of the ionization gas are electrically neutral.

24. A lithography apparatus, comprising the mass spectrometer of claim 1 .

25. The lithography apparatus of claim 24 , wherein the lithography apparatus is an EUV lithography apparatus.

26. The lithography apparatus of claim 25 , wherein the EUV lithography apparatus comprises a projection system, and the mass spectrometer is connected to the projection system.

Assignees

• Zeiss Carl Smt Gmbh
• Zeiss Carl Microscopy Gmbh

Inventors

• Fedosenko Gennady
• Aliman Michel
• Chung Hin Yiu Anthony
• Ranck Albrecht
• Gorkhover Leonid

Classifications

• H01J49/145 Primary

  using chemical ionisation · CPC title

• H01J49/0027

  Methods for using particle spectrometers · CPC title

• H01J49/04 Primary

  Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components · CPC title

• H01J49/14

  using particle bombardment, e.g. ionisation chambers · CPC title

• H01J49/147

  with electrons, e.g. electron impact ionisation, electron attachment (H01J49/145 takes precedence) · CPC title