Gas discharge source for generating EUV-radiation
View Patent ↗The present invention relates to a gas discharge source, for generating EUV radiation and/or soft X-radiation, comprising at least two electrode bodies ( 110,120 ), of which a first electrode body ( 110 ) comprises a rotatably mounted electrode disk ( 100 ). The source further comprises a rotary drive ( 130 ) for the electrode disk, a device for applying a liquid film of a target material ( 140 ) onto a radial outer surface of the electrode disk ( 100 ), and a laser that is focussed, within a discharge area ( 240 ), onto the radial outer surface of the electrode disk ( 100 ) to evaporate target material. The source is characterized by an intermediate space ( 160 ) is formed between the electrode bodies, which intermediate space has a reduced width of <5 mm outside the discharge area ( 240 ), which is smaller than the intermediate space in the discharge area. The source enables the generated radiation to be emitted in a simple manner through a larger solid angle, without being shadowed by the electrodes.
1. Gas discharge source for generating EUV radiation and/or soft X-radiation, the source comprising
two electrode bodies, of which a first electrode body comprises a rotatably mounted electrode disk,
a rotary drive for the electrode disk,
a device for applying a liquid film of a target material ( 140 ) onto a radial outer surface of the electrode disk, and
a laser for emitting a laser beam which is focused, in a discharge area, onto the radial outer surface of the electrode disk, in order to evaporate target material from the liquid film, wherein between the electrode bodies an intermediate space is formed, the width of the intermediate space outside the discharge area is less than 5 mm relative to a distance in the discharge area.
2. Gas discharge source as claimed in claim 1 , wherein the second electrode body does not project above the electrode disk in a direction perpendicular to the disk's radial outer surface in the discharge area.
3. Gas discharge source as claimed in claim 2 , wherein the electrode disk projects above the second electrode body in a direction perpendicular to its radial outer surface in the discharge area.
4. Gas discharge source as claimed in claim 1 , wherein the second electrode body laterally encloses the first electrode body.
5. Gas discharge source as claimed in claim 4 , wherein the second electrode body comprises a gap in a part facing the discharge area for allowing passage of the electrode disk, and is otherwise designed so as to be rotationally symmetrical about the first electrode body.
6. Gas discharge source as claimed in claim 4 , wherein the second electrode body is dome-shaped.
7. Gas discharge source as claimed in claim 1 , wherein the rotary drive comprises a belt via which a motor ( 230 ) drives the electrode disk.
8. Gas discharge source as claimed in claim 1 , wherein the electrode bodies are arranged in a vacuum vessel, in which a gas pressure of ≧1 Pa has been set.
9. Gas discharge source as claimed in claim 1 , wherein the intermediate space is designed so as to be a gap between the electrode bodies.
10. Gas discharge source as claimed in claim 1 , wherein the intermediate space is at least partly filled with an insulating material.
11. Gas discharge source as claimed in claim 1 , wherein at the location of the discharge area, an intermediate plate is arranged having a slot for allowing passage of the electrode disk and one or more apertures for prescribing current paths between the electrode bodies.
12. Gas discharge source as claimed in claim 1 , wherein the second electrode body is stationary.
13. Gas discharge source as claimed in claim 1 , wherein the second electrode body comprises one or more rotatable components ( 280 ), which extend as far as the discharge area.
14. Gas discharge source as claimed in claim 1 , wherein the discharge source comprises a device for pre-ionizing a gas present in the discharge area.