PLASMA GENERATOR

1 . An arrangement for generating plasma, the arrangement comprising a primary plasma source ( 1 ) arranged for generating plasma, a hollow guiding body ( 11 ) arranged for guiding at least a portion of the plasma generated by the primary plasma source to a secondary plasma source ( 25 ), and an outlet ( 14 ) for emitting at least a portion of the plasma and components thereof from the arrangement.

2 . The arrangement of claim 1 , wherein the primary plasma source ( 1 ) comprises a primary source chamber ( 15 ) in which the plasma may be formed and a first coil ( 4 ) for generating the plasma in the primary source chamber, the chamber comprising an inlet ( 5 ) for receiving an input gas, and one or more outlets for removal of at least a portion of the plasma from the source chamber and into the guiding body ( 11 ).

3 . The arrangement of claim 1 or 2 , wherein the secondary plasma source ( 25 ) comprises a secondary source chamber ( 16 ) occupying at least a portion of the guiding body ( 11 ).

4 . The arrangement of any one of the preceding claims, wherein the secondary plasma source ( 25 ) does not include a coil for enhancing or generating plasma.

5 . The arrangement of any one of the preceding claims, wherein the secondary plasma source ( 25 ) comprises a secondary source chamber ( 16 ) and wherein the arrangement is adapted to generate a high brightness plasma in the secondary source chamber.

6 . The arrangement of any one of the preceding claims, wherein, in operation, the primary plasma source ( 1 ) generates a primary plasma via inductive coupling, and the secondary plasma source ( 25 ) generates a secondary plasma via capacitive coupling.

7 . The arrangement of any one of the preceding claims, further comprising an electrode ( 30 , 32 , 34 ) located near the outlet of the arrangement, wherein, in operation, the coil ( 4 ) of the primary plasma source ( 1 ) is capacitively coupled to the electrode via the plasma generated by the primary plasma source and/or the secondary plasma source.

8 . The arrangement of claim 7 , wherein the electrode is maintained at a fixed potential with respect to a voltage supplied to the coil ( 4 ) of the primary plasma source ( 1 ).

9 . The arrangement of claim 7 , wherein the electrode is grounded with respect to a voltage supplied to the coil ( 4 ) of the primary plasma source ( 1 ).

10 . The arrangement of claim 9 , further comprising an additional electrode ( 34 ) arranged for repelling plasma ions in the guiding body ( 11 ).

11 . The arrangement of any one of the preceding claims, wherein the primary plasma source ( 1 ) comprises a primary source chamber ( 15 ) in which primary plasma is generated and the secondary plasma source ( 25 ) comprises a secondary source chamber ( 16 ) in which the primary plasma is enhanced and/or secondary plasma is generated, and wherein the primary source chamber is larger than the secondary source chamber.

12 . The arrangement of claim 11 , further comprising a pressure regulator for regulating pressure in the primary source chamber, and wherein a flow or pressure restriction is provided between the primary and secondary source chambers.

13 . The arrangement of claim 12 , wherein, in use, the restriction is adapted to maintain an operating pressure in the secondary source chamber at a lower pressure than in the primary source chamber.

14 . The arrangement of any one of claims 11 - 13 , wherein the arrangement is adapted for regulating the pressure in the secondary source chamber.

15 . The arrangement of any one of claims 11 - 14 , wherein the arrangement is adapted for regulating the pressure in both the primary and secondary source chambers.

16 . The arrangement of any one of claims 11 - 15 , wherein the primary source chamber has a diameter of 20 mm or more, and the secondary source chamber has a diameter of less than 20 mm.

17 . The arrangement of any one of claims 11 - 16 , wherein the secondary source chamber has an end section for directing plasma in a desired direction.

18 . The arrangement of any one of claims 11 - 17 , wherein the secondary source chamber has a relatively small cross-sectional area in comparison with the primary source chamber.

19 . The arrangement of any one of claims 11 - 18 , wherein the secondary source chamber is a tube.

20 . The arrangement of any one of claims 11 - 19 , wherein the secondary source chamber has a length longer than the primary source chamber in a direction of the flow of plasma from the primary source chamber.

21 . The arrangement of any one of claims 11 - 20 , wherein the secondary source chamber generates plasma at a position close to an outlet of the arrangement.

22 . The arrangement of any one of the preceding claims, wherein the primary plasma source ( 1 ) is located further from the outlet ( 14 ) than the secondary plasma source ( 25 ).

23 . The arrangement of any one of the preceding claims, wherein, in operation, at least a portion of the plasma generated by the primary plasma source ( 1 ) travels through the guiding body ( 11 ) to the secondary plasma source ( 25 ) to stabilize the formation of plasma by the secondary plasma source ( 25 ).

24 . The arrangement of any one of the preceding claims, wherein the hollow guiding body ( 11 ) comprises a funnel section ( 10 ) located at the outlet of the primary plasma source ( 1 ) arranged for guiding plasma generated by primary plasma source into the guiding body.

25 . The arrangement of any one of the preceding claims, wherein the guiding body ( 11 ) comprises a quartz material or has an inner surface comprising a quartz material.

26 . The arrangement of any one of the preceding claims, wherein the guiding body ( 11 ) is in the form of a tube or duct.

27 . The arrangement of any one of the preceding claims, wherein the guiding body ( 11 ) has a bend ( 13 ) or elbow ( 12 ) to direct plasma from the outlet ( 14 ) onto an area to be cleaned by the plasma.

28 . The arrangement of any one of the preceding claims, wherein the primary plasma source ( 1 ) comprises a primary source chamber ( 15 ) in which the plasma may be formed, the arrangement further comprising an aperture plate ( 31 ) positioned between the primary source chamber and the guiding body ( 11 ) and the aperture plate having one or more apertures for permitting flow of the plasma from the primary source chamber into the guiding body.

29 . The arrangement of any one of the preceding claims, further comprising an aperture plate ( 32 ) at or near the outlet ( 14 ) of the guiding body to confine at least a portion of the plasma in the guiding body from exiting through the outlet.

30 . A method for generating a plasma, comprising flowing an input gas into a primary source chamber, energizing a first coil to form a primary plasma in the primary source chamber, flowing at least a portion of the primary plasma into a secondary source chamber, and generating a secondary plasma in the secondary source chamber.

31 . The method of claim 30 , wherein flowing the primary plasma into the secondary source chamber comprises flowing the plasma into a guiding body, at least a portion of the guiding body forming the secondary source chamber.

32 . The method of claim 30 or 31 , wherein the first plasma is flowed from the primary source chamber through a restriction into a secondary source chamber.

33 . The method of any one of claims 30 - 32 , wherein the secondary source chamber is not provided with a coil for forming a plasma.

34 . The method of any one of claims 30 - 33 , wherein the primary plasma is formed in the primary source chamber via inductive coupling, and the secondary plasma is generated in the secondary source chamber via capacitive coupling.

35 . The method of any one of claims 30 - 34 , further comprising regulating pressure in the primary source chamber and the secondary source chamber.

36 . The method of claim 35 , wherein regulating the pressure comprises maintaining a lower pressure in the secondary source chamber than in the primary source chamber.

37 . The method of any one of claims 30 - 36 , wherein the secondary source chamber is smaller than the primary source chamber.

38 . The method of any one of claims 30 - 37 , further comprising stabilizing the formation of plasma in the secondary source chamber with the primary plasma flowing from the primary source chamber.

39 . An cleaning apparatus for cleaning contaminants from a surface, the apparatus comprising an arrangement for generating plasma according to any one of claims 1 - 29 , and means for directing the plasma onto the surface to be cleaned.

40 . A charged particle lithography machine, comprising a beamlet generator for generating a plurality of charged particle beamlets and a plurality of beamlet manipulator elements for manipulating the beamlets, each beamlet manipulator element comprising a plurality of apertures through which the beamlets pass, the machine further comprising an arrangement according to any one of claims 1 - 29 adapted to generate plasma and direct the plasma onto a surface of one or more of the beamlet manipulator elements.