Method and system for the removal and/or avoidance of contamination in charged particle beam systems

Patent metadata

Field	Value
Publication number	US-9981293-B2
Application number	US-201615135138-A
Country	US
Kind code	B2
Filing date	Apr 21, 2016
Priority date	Apr 21, 2016
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A charged particle beam system is disclosed, comprising:
a charged particle beam generator for generating a beam of charged particles; a charged particle optical column arranged in a vacuum chamber, wherein the charged particle optical column is arranged for projecting the beam of charged particles onto a target, and wherein the charged particle optical column comprises a charged particle optical element for influencing the beam of charged particles; a source for providing a cleaning agent; a conduit connected to the source and arranged for introducing the cleaning agent towards the charged particle optical element;

wherein the charged particle optical element comprises:
a charged particle transmitting aperture for transmitting and/or influencing the beam of charged particles, and at least one vent hole for providing a flow path between a first side and a second side of the charged particle optical element,

wherein the vent hole has a cross section which is larger than a cross section of the charged particle transmitting aperture.

Further, a method for preventing or removing contamination in the charged particle transmitting apertures is disclosed, comprising the step of introducing the cleaning agent while the beam generator is active.

First claim

The invention claimed is:

1. Charged particle beam system, comprising:
a charged particle beam generator for generating a beam of charged particles;
a charged particle optical column arranged in a vacuum chamber, wherein said charged particle optical column is arranged for projecting said beam of charged particles onto a target, and wherein said charged particle optical column comprises a charged particle optical element for influencing said beam of charged particles;
a source for providing cleaning agent;
a conduit connected to said source and arranged for introducing said cleaning agent towards said charged particle optical element;
a vacuum pump for maintaining a vacuum in said vacuum chamber;

wherein said charged particle optical element comprises:
a beam stop element, said beam stop element comprising:
a plurality of charged particle transmitting apertures for passage of charged particle beams and a non-aperture area for blocking passage of charged particles, and
a plurality of vent holes for providing a flow path through said beam stop element,
wherein the vent holes have a larger cross section than a cross section of the charged particle transmitting aperture,
wherein the system further comprises:
a projection lens comprising a plurality of projection lens apertures for focusing said charged particle beams,
wherein said projection lens is arranged downstream said beam stop element, and
wherein said projection lens and said beam stop element are arranged such that any charged particles passing through one or more of said vent holes are blocked by a non-aperture area of said projection lens.

2. System according to claim 1 , wherein said vent holes have a cross section of one of the following shapes: circular, slit-shaped, or elliptical.

3. System according to claim 1 , wherein said vent holes are arranged next to said charged particle transmitting apertures.

4. System according to claim 3 , wherein said charged particle transmitting apertures are arranged in one or more groups and the vent holes are arranged substantially along said one or more groups.

5. System according to claim 4 , wherein said vent holes are arranged in one or more one dimensional arrays.

6. System according to claim 4 , wherein said vent holes are arranged in one or more two-dimensional arrays.

7. System according to claim 4 , wherein said vent holes are arranged on either sides of said one or more groups of plurality of charged particle transmitting apertures.

8. System according to claim 3 , wherein said vent holes are arranged immediately adjacent an area comprising a plurality of said charged particle transmitting apertures.

9. System according to claim 3 , wherein said vent holes are arranged with a pitch which is equal to or larger than a dimension of said vent holes, said pitch in particular being in the range from 1 to 3 times the dimension of said vent holes.

10. System according to claim 9 , wherein said pitch is equal to or larger than a dimension of said vent holes along a direction of alignment of said vent holes.

11. System according to claim 1 , wherein said vent holes have a cross section in a range from half of a cross section of said projection lens apertures to two times the cross section of said projection lens apertures.

12. System according to claim 1 , wherein said projection lens further comprises a plurality of dummy apertures arranged around a group of said projection lens apertures, wherein said vent holes are arranged such that any charged particle passing through said vent holes are blocked by an area located laterally outside said dummy apertures.

13. System according to claim 1 , further comprising
a second aperture element comprising a plurality of apertures for forming a plurality of charged particle beams from said beam of charged particles, said second aperture element arranged between said charged particle beam generator and said beam stop element, and
a restriction element provided between said charged particle beam generator and said second aperture element, said restriction element arranged for preventing or at least reducing a flow of said cleaning agent and/or products thereof to said charged particle beam generator.

14. System according to claim 13 , further comprising:
a beam generator module, said charged particle beam generator being arranged in said beam generator module;
a modulation module, said second aperture element being arranged in said modulation module;
wherein said restriction element is movably connected to said beam generator module and arranged for abutting said modulation module by means of gravity and/or a spring force.

15. System according to claim 14 , wherein said restriction element is connected to a first wall of said beam generator module, said restriction element at least partly surrounding a perimeter of an opening in said first wall for passage of said beam of charged particles, wherein said restriction element comprises an at least partially ring-shaped element, in particular a ceramic ring, said at least partially ring-shaped element being movably arranged with respect to said first wall in a direction toward or away from said modulation module.

16. System according to claim 15 , further comprising a confining element for confining a movement of said restriction element with respect to said first wall.

17. System according to claim 16 , wherein said restriction element is provided with one or more protrusions and said confining element is arranged to cooperate with said protrusions to confine movement of said restriction element.

18. System according to claim 13 , further comprising:
a modulation element arranged downstream said second aperture element, said modulation element comprising a second plurality of apertures for passage of said charged particle beams and deflectors associated with said second plurality of apertures, said deflectors arranged to selectively deflect or not deflect said charged particle beams wherein said beam stop element arranged downstream said modulation element,
said modulation element and said beam stop element arranged to function together to let pass or to block said selectively deflected charged particle beams.

19. System according claim 1 , wherein electrical connections within said charged particle optical system are provided with a protective coating.

20. Method for preventing or removing contamination of a charged particle transmitting apertures in a charged particle beam system, the charged particle beam system comprising:
a charged particle beam generator for generating a beam of charged particles;
a charged particle optical column arranged in a vacuum chamber, wherein said charged particle optical column is arranged for projecting said beam of charged particles onto a target, and wherein said charged particle optical column comprises a charged particle optical element for influencing said beam of charged particles;

wherein said charged particle optical element comprises a beam stop element, said beam stop element comprising:
plurality of charged particle transmitting apertures for passage of charged particle beams and a non-aperture area for blocking passage of charged particles, and
a plurality of vent holes for providing a flow path through said beam stop element, wherein the vent holes have a larger cross section than a cross section of the charged particle transmitting aperture,
a source for providing cleaning agent;
a conduit connected to said source and arranged for introducing sa

Assignees

• Mapper Lithography Ip Bv

Inventors

• Smits Marc
• Koning Johan Joost
• Lodewijk Chris Franciscus Jessica
• Mook Hindrik Willem
• Lattard Ludovic

Classifications

• B08B7/04 Primary

  by a combination of operations · CPC title

• H01J2237/0492

  Lens systems · CPC title

• H01J2237/0453

  multiple apertures · CPC title

• H01J37/3177 Primary

  Multi-beam, e.g. fly's eye, comb probe · CPC title

• H01J2237/006

  Details of gas supplies, e.g. in an ion source, to a beam line, to a specimen or to a workpiece, (H01J37/3244 takes precedence; environmental cells for electron microscopes H01J2237/2003; microscopes with environmental specimen chamber H01J2237/2608) · CPC title