Environmental cell for charged particle beam system

Patent metadata

Field	Value
Publication number	US-9679741-B2
Application number	US-94220110-A
Country	US
Kind code	B2
Filing date	Nov 9, 2010
Priority date	Nov 9, 2010
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

An environmental cell for a charged particle beam system allows relative motion between the cell mounted on an X-Y stage and the optical axis of the focusing column, thereby eliminating the need for a sub-stage within the cell. A flexible cell configuration, such as a retractable lid, permits a variety of processes, including beam-induced and thermally-induced processes. Photoelectron yield spectroscopy performed in a charged particle beam system and using gas cascade amplification of the photoelectrons allows analysis of material in the cell and monitoring of processing in the cell. Luminescence analysis can be also performed using a retractable mirror.

First claim

We claim as follows:

1. A charged particle beam system, comprising:
a source of charged particles;
a particle optical column for producing a focused beam of particles and directing the beam toward the sample, the particle beam optical column having an optical axis;
an evacuable sample chamber;
a motion stage positioned in the evacuable chamber, the motion stage movable relative to the optical axis;
a cell located within the evacuable chamber for containing a sample for processing, the cell including:
a first portion of the cell having a body forming an enclosure, the first portion positioned on the motion stage and movable with the motion stage
at least one gas inlet formed in the first portion for introducing gas into the cell;
a second portion of the cell including a radially outwardly extending member fixed with respect to the particle optical column, wherein the body of the first portion and the radially outwardly extending member of the second portion of the cell oppose each other to create a seal during motions of the stage, the seal formed by a first radially outwardly extending flat surface on the radially outwardly extending member and a second flat surface that extends radially outwardly from the first portion of the cell, the two flat surfaces opposing each other to form the seal that reduces gas flow from the cell interior to the evacuable chamber; and
a flexible bellows formed in the first portion to allow vertical movement between the first portion and the second portion, the flexible bellows having sufficient stiffness to provide enough pressure between the second flat surface and the first flat surface to maintain a contact seal, while still allowing relative motion between the first and second portions of the cell.

2. The charged particle beam system of claim 1 in which the first flat surface is mounted onto a lens of the particle optical column.

3. The charged particle beam system of claim 1 in which the first flat surface and the second flat surface comprise stainless steel, aluminum or a fluoropolymer such as polytetrafluoroethylene.

4. The charged particle beam system of claim 1 in which the first flat surface and the second flat surface seal without the use of an elastomer.

5. The charged particle beam system of claim 1 in which the seal is a contact seal.

6. The charged particle beam system of claim 1 in which the seal is a gap of less than 1 mm.

7. The charged particle beam system of claim 1 in which the cell includes a photon transparent window.

8. The charged particle beam system of claim 1 in which the portion of the cell fixed with respect to the particle optical column can be retracted without opening the evacuable chamber.

9. The charged particle beam system of claim 8 further comprising a radiation detector for detecting radiation emitted from the sample upon impact of the electron beam.

10. The charged particle beam system of claim 9 in which the radiation detector detects x-rays for x-ray analysis or light for luminescence analysis.

11. The charged particle beam system of claim 1 in which the cell includes a heater for heating the sample.

12. The charged particle beam system of claim 11 which includes a cooler to cool the portion of the cell positioned on the stage.

13. The charged particle beam system of claim 1 in which the cell includes a cooler to cool the sample.

14. The charged particle beam system of claim 1 further comprising a radiation source capable of irradiating the sample with radiation over a sufficient range of frequencies to produce a photoluminescence spectrum or a photoelectron yield spectrum.

15. The charged particle beam system of claim 1 in which the cell further includes within the cell a detector electrode for detecting an electron signal from the sample amplified by gas cascade amplification and in which the charged particle system further includes a photon detector within the evacuable sample chamber and outside the cell.

16. A method of charged particle beam processing, comprising:
providing a charged particle beam system having;
an evacuable chamber;
a motion stage;
a focusing column; and
an optical axis;

providing an environmental cell, positioned inside the evacuable chamber, for processing the sample in a gaseous environment, the environmental cell having a first part forming an enclosure with a first radially outwardly extending flange having a first flat surface, the flange connected to the motion stage and positioned on the motion stage and a second part including a second outwardly extending flange having a second flat surface that opposes the first outwardly extending flange to create a pressure limiting aperture for the cell that reduces gas flow from the cell interior to the evacuable chamber; moving the stage while maintaining the pressure limiting aperture fixed relative to the optical axis by applying pressure from the first flat surface to the second flat surface using a flexible bellows formed in the first part to allow vertical movement between the first part and the second part, the flexible bellows having sufficient stiffness to provide sufficient pressure between the second flat surface and the first flat surface to maintain a contact seal, while still allowing relative motion between the first and second portions of the cell; and
directing the charged particle beam towards the sample.

17. The method of claim 16 in which moving the stage includes lowering the environmental cell so as to enable opening and closing of the cell within the chamber by separating the sealing portion of the environmental cell from the sealing member.

18. The method of claim 17 further comprising inserting a photon collector between the cell and the focusing column, and using the photon collector to direct photons emitted by the sample to a detector.

19. The method of claim 18 in which the photons are excited by the charged particle beam.

20. The method of claim 18 further comprising heating the sample in a gaseous environment, and collecting photons before and after a sample is processed in a gaseous environment.

21. The method of claim 20 further comprising cooling the sample below room temperature while the detector is used to collect photons emitted from the sample.

22. A charged particle beam system, comprising:
a source of charged particles;
an evacuable sample chamber;
a particle optical column for producing a focused beam of particles and directing the beam toward a sample in an environmental cell in the evacuable sample chamber;
a photoelectron yield spectroscopy (PYS) photon source capable of directing photons in a single convergent beam scanned over a range of frequencies to produce a PYS spectrum by causing the sample to emit photoelectrons at the different frequencies over the range of frequencies; and
an electrode for detecting a secondary electron signal due to the impact of the charged particles onto the sample or for detecting the photoelectron signal after the secondary electron signal or the photoelectron signal is amplified in a gas cascade to form a PYS spectrum including the scanned frequencies.

23. The charged particle beam system of claim 22 in which the electrode is connected to the sample or the stage to detect current flowing through the sample or the stage as a measure of the photoelectron emission current.

24. The charged particle beam system of claim 22 in which the radiation source is a laser.

Assignees

• Novak Libor
• Uncovsky Marek
• Toth Milos
• Cafourek Martin
• Parker William
• Straw Marcus
• Emerson Mark
• Fei Co

Inventors

• Novak Libor
• Uncovsky Marek
• Toth Milos
• Cafourek Martin
• Parker William
• Straw Marcus
• Emerson Mark

Classifications

• H01J37/244

  Detectors; Associated components or circuits therefor · CPC title

• H01J2237/024

  Moving components not otherwise provided for · CPC title

• H01J2237/2001

  Maintaining constant desired temperature · CPC title

• H01J37/20 Primary

  Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support · CPC title

• H01J37/18

  Vacuum locks {; Means for obtaining or maintaining the desired pressure within the vessel} · CPC title