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

1. A method for preventing or removing contamination of a charged particle transmitting aperture in a charged particle beam system comprising a charged particle optical column arranged in a vacuum chamber, a cleaning agent source, and a conduit connected to the cleaning agent source, the charged particle optical column being configured to project a beam of charged particles onto a target and comprising:

a charged particle optical element configured to influence the beam of charged particles and comprising:

the charged particle transmitting aperture configured to transmit and/or influence the beam of charged particles, and

a vent hole configured to provide a flow path between a first side and a second side of the charged particle optical element,

the method comprising:

introducing the cleaning agent from the cleaning agent source towards the charged particle optical element via the conduit extending into and within the vacuum chamber to guide the cleaning agent towards the charged particle optical element; and

directing the beam of charged particles towards the charged particle optical element while introducing the cleaning agent towards the charged particle optical element, at least part of species of the cleaning agent flowing at least through the charged particle optical element via the vent hole.

2. The method of claim 1 , wherein introducing the cleaning agent towards the charged particle optical element comprises: introducing the cleaning agent towards the charged particle optical element while maintaining a vacuum in the vacuum chamber.

3. The method of claim 2 , wherein maintaining the vacuum comprises providing the flow at least through the charged particle optical element via the vent hole.

4. The method of claim 1 , wherein introducing the cleaning agent towards the charged particle optical element comprises: guiding the cleaning agent by use of the conduit over a surface of the charged particle optical element.

5. The method of claim 4 , wherein introducing the cleaning agent towards the charged particle optical element comprises: introducing the cleaning agent towards the charged particle optical element while the beam of charged particles is present at or near the aperture of the charged particle optical element.

6. The method of claim 1 , wherein the charged particle beam system comprises a charged particle beam generator that is configured to generate the beam of charged particles, wherein introducing the cleaning agent towards the charged particle optical element comprises: introducing the cleaning agent towards the charged particle optical element while the beam generator is generating the beam of charged particles.

7. The method of claim 3 , wherein the vacuum chamber being connected to a vacuum arrangement, wherein providing the flow via the vent hole comprises providing the flow at least through the charged particle optical element via the vent hole to the vacuum arrangement.

8. The method of claim 1 , wherein the charged particle optical element comprises an array of charged particle transmitting apertures, wherein projecting the beam of charged particles comprises projecting a plurality of beams of charged particles onto a target through the array of charged particle transmitting apertures.

9. The method of claim 3 , wherein providing the flow at least through the charged particle optical element via the vent hole comprises guiding the cleaning agent over a surface of the charged particle optical element.

10. The method of claim 9 , wherein the surface of the charged particle optical element comprising the charged particle transmitting aperture comprises an array of charged particle transmitting apertures.

11. The method of claim 1 , further comprising preventing any charged particles passing through the vent hole from reaching the target, or preventing charged particles from reaching the vent hole.

12. A charged particle beam system comprising a charged particle optical column arranged in a vacuum chamber and a cleaning agent source configured to provide a cleaning agent, and a conduit connected to the cleaning agent source, the charged particle optical column configured to project a beam of charged particles onto a target and comprising:

a charged particle optical element configured to influence the beam of charged particles and comprising: a charged particle transmitting aperture configured to transmit and/or influence the beam of charged particles, and a vent hole configured to provide a flow path between a first side and a second side of the charged particle optical element,

wherein the charged particle optical column is configured to prevent or remove contamination of the charged particle transmitting aperture by directing the beam of charged particles towards the charged particle optical element while introducing the cleaning agent towards the charged particle optical element, at least part of species of the cleaning agent flowing at least through the charged particle optical element via the vent hole,

wherein the cleaning agent is introduced towards the charged particle optical element via the conduit extending into and within the vacuum chamber to guide the cleaning agent towards the charged particle optical element.

13. The system of claim 12 , wherein the cleaning agent is introduced towards the charged particle optical element while the beam of charged particles is present at or near the aperture of the charged particle optical element.

14. The system of claim 12 , wherein the flow through at least through the charged particle optical element via the vent hole comprises guiding the cleaning agent over a surface of the charged particle optical element.

15. The system of claim 12 , wherein the cleaning agent is introduced towards the charged particle optical element via the conduit connected to the cleaning agent source while the beam of charged particles are projected towards the target.

16. The system of claim 12 , wherein the vent hole has a cross section that is larger than a cross section of the charged particle transmitting aperture.

17. The system of claim 12 , wherein the charged particle beam system comprises a charged particle beam generator that is configured to generate the beam of charged particles.

18. The system of claim 17 , wherein the charged particle optical element comprises an array of charged particle transmitting apertures and the charged particle optical column is configured to project a plurality of beams of charged particles onto a target through the array of charged particle transmitting apertures.

19. The system of claim 12 , further comprising a vacuum arrangement connected to the vacuum chamber so that the at least part of species of the cleaning agent flows to the vacuum arrangement at least through the charged particle optical element via the vent hole.

20. Method for preventing or removing contamination of an array of charged particle transmitting apertures in a charged particle beam system arranged in a vacuum chamber that is connected to a vacuum source, the charged particle beam system comprising a charged particle optical column for projecting a plurality of beams of charged particles onto a target through the array of charged particle transmitting apertures,

the charged particle optical column comprising a charged particle optical element for influencing the beams of charged particles, the charged particle optical element comprises the array of charged particle transmitting apertures for transmitting or influencing the plurality beams of charged particles, and a vent hole providing a flow path from a first side to a second side of the charged particle optical element, the vent hole having a larger cross section than a cross section of an aperture of the array of charged particle transmitting apertures;

the method comprising the following steps:

providing from a cleaning agent source a cleaning agent;

introducing the cleaning agent towards the charged particle optical element via a conduit connected to the cleaning agent source while the beams of charged particles are present at or near apertures of the charged particle optical element;

guiding the cleaning agent over a surface of the charged particle optical element by use of the conduit, the surface comprising the array of charged particle transmitting apertures; and

maintaining a vacuum in the vacuum chamber, wherein the step of maintaining a vacuum comprises enabling a flow or movement of species of the cleaning agent or contaminants at least through the charged particle optical element via the vent hole to the vacuum source.