Foil trap device with improved heat resistance
The present invention relates to a foil trap device for debris mitigation, in particular in an EUV system. The foil trap comprises a plurality of spaced apart foils ( 4 ) extending from an entrance side towards an exit side of the foil trap, said foils ( 4 ) being arranged to allow a straight pass of radiation between the entrance side and the exit side. The foils ( 4 ) are coated at least at entrance side edges with a layer ( 8, 11 ) of a carbon material containing a fraction of at least 60% of sp3-hybridized carbon atoms, or with a layer ( 8, 11 ) of carbon nanotubes. As an alternative, the foils ( 4 ) are made of a bulk carbon material of the above composition. The proposed foil trap offers the combination of a high thermal conductivity, a high thermo-chemical resistance against Sn and other liquid metals and a high mechanical stiffness.
1. A foil trap device for debris mitigation comprising a plurality of spaced apart foils extending from an entrance side towards an exit side of the foil trap device, said foils being arranged to allow a straight pass of radiation between the entrance side and the exit side, wherein the foils are coated at least at entrance side edges with a layer of a carbon material containing a fraction of at least 60% of sp3-hybridized carbon atoms, or with a layer of carbon nanotubes, or comprise a bulk carbon material containing a fraction of at least 60% of sp3-hybridized carbon atoms.
2. The device according to claim 1 , wherein said layer of a carbon material contains a ratio of sp3/sp2 bonds of >60%.
3. The device according to claim 1 , wherein the foils comprising a base material selected from the group consisting of: Mo, steel, Cu, W, Ta, Ti and Zr.
4. The device according to claim 3 , wherein said foils comprise an intermediate carbide layer formed between said layer of carbon material and said base material of the foils.
5. The device according to claim 1 , wherein the foils are completely coated with said layer of carbon material or said layer of carbon nanotubes.
6. The device according to claim 1 , wherein said layer has a thickness of between 1 μm and 10 μm.
7. The device according to claim 1 , wherein the foils have a thickness of between 20 μm and 200 μm.