Encapsulation of electrodes in solid media for use in conjunction with fluid high voltage isolation

• US 8,642,974 B2
• Filed: 06/21/2011
• Issued: 02/04/2014
• Est. Priority Date: 12/30/2009
• Status: Active Grant

• Current Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Original Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Inventors: Kellogg, Sean, Wells, Andrew B., McGinn, James B., Parker, N. William, Utlaut, Mark W., Graupera, Anthony
• Primary Examiner(s): Vanore, David A
• Assistant Examiner(s): STOFFA, WYATT A
• Application Number:
  US13/165,556
• Publication Number:
  US 20110272592A1
• Time in Patent Office: 959 Days
• Field of Search: 250/423.R, 250/396.R, 250/493.1
• US Class Current: 250/423.R
• CPC Class Codes: H01J 2237/002 Cooling arrangements of objects being observed or treated H01J2237/2001
• CPC Class Codes: H01J 2237/061 Construction
• CPC Class Codes: H01J 2237/0817 Microwaves
• CPC Class Codes: H01J 2237/31749 Focused ion beam
• CPC Class Codes: H01J 27/16 using high-frequency excitation, e.g. microwave excitation
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: H05H 1/4652 using inductive coupling means, e.g. coils

Abstract

An inductively-coupled plasma source for a focused charged particle beam system includes a conductive shield that provides improved electrical isolation and reduced capacitive RF coupling and a dielectric fluid that insulates and cools the plasma chamber. The conductive shield may be enclosed in a solid dielectric media. The dielectric fluid may be circulated by a pump or not circulated by a pump. A heat tube can be used to cool the dielectric fluid.

Claims

1. A charged particle beam system, comprising:

a plasma source having;

a plasma chamber having a wall composed of a dielectric material, the wall having an interior surface and an exterior surface;

a conductor coiled at least one time around the plasma chamber;

a fluid surrounding and in thermal contact with at least a portion of the plasma chamber, the fluid being a liquid; and

a source electrode for electrically biasing the plasma to a high voltage; and

one or more focusing lenses for focusing charged particles from the plasma source onto a sample, the charged particle system lacking a pump for actively pumping the fluid around the portion of the plasma chamber, the fluid moving only by convection and/or gravity.

2. The charged particle beam system of claim 1 in which a portion of the fluid is positioned between the plasma chamber and the conductor.

3. The charged particle beam system of claim 1 in which the fluid has a dielectric constant greater than 5.

4. The charged particle beam system of claim 1 in which the fluid comprises water or a fluorine compound.

5. The charged particle beam system of claim 1 further comprising a conductive shield positioned between the plasma chamber and the conductor, at least a portion of the fluid positioned between the plasma chamber and the conductive shield.

6. The charged particle beam system of claim 5 further comprising at least one cooling device for cooling the fluid.

7. The charged particle beam system of claim 6 in which the at least one cooling device comprises a thermoelectric cooler.

8. The charged particle beam system of claim 1 further comprising at least one heat pipe in which a portion of the at least one heat pipe is in thermal contact with the fluid such that heat from the fluid can dissipate through the at least one heat pipe to cool the fluid.

9. The charged particle beam system of claim 8 further comprising a cooling fin in thermal contact with the at least one heat pipe, the cooling fin for dissipating heat from the at least one heat pipe and transferring the heat into a surrounding environment.

10. The charged particle beam system of claim 8 in which the heat pipe contains a dissipating fluid, said dissipating fluid being separate from the fluid surrounding and in thermal contact with at least a portion of the plasma chamber.

11. A method of processing a sample, comprising:

varying a voltage across an antenna to provide radio frequency energy into a plasma chamber;

applying a high voltage to the plasma to bias the plasma relative to a work piece to be processes;

conducting heat away from the plasma chamber using a liquid in contact with at least a portion of the plasma chamber, the liquid absorbing heat from the plasma chamber during operation moving only by convection and/or gravity and not being actively pumped in contact with the plasma chamber;

extracting charged particles from a plasma chamber; and

directing the charged particles toward the work piece to process or form an image of the work piece.

12. The method of claim 11 in which conducting heat away from the plasma chamber includes using a fluid positioned between the plasma chamber and the antenna.

13. The method of claim 11 in which using a liquid in contact with at least a portion of the plasma chamber includes using a liquid having a dielectric constant greater than 5.

14. The method of claim 11 in which using a liquid in contact with at least a portion of the plasma chamber includes using water or a fluorine compound.

15. The method of claim 11 in which a conductive shield is positioned between the plasma chamber and the antenna and in which using a liquid in contact with at least a portion of the plasma chamber includes using a liquid that is at least in part positioned between the plasma chamber and the conductive shield.

16. The method of claim 11 further comprising cooling the fluid.

17. The method of claim 16 in which cooling the liquid comprises cooling the liquid using a thermoelectric cooler.

18. The method of claim 17 in which cooling the liquid comprises cooling the liquid using at least one heat pipe.

19. The method of claim 18 in which cooling the liquid comprises transferring the heat into a surrounding environment by a cooling fin in thermal contact with the at least one heat pipe.

20. The method of claim 18 in which the heat pipe contains a dissipating fluid, said dissipating fluid being separate from the fluid surrounding and in thermal contact with at least a portion of the plasma chamber.