Filter window, lithographic projection apparatus, filter window manufacturing method, device manufacturing method and device manufactured thereby
A filter window for EUV lithography includes a pellicle, and a wire structure for supporting the pellicle. The pellicle includes a first layer that includes at least one of AlN, Ru, Ir, Au, SiN, Rh. The pellicle has a very low EUV absorption in combination with a minimal oxidation rate. The thickness of the pellicle may be between 30 nm and 100 nm. It can be easily checked that absorption of EUV radiation of such a thin pellicle is equal to known filter windows, i.e. about 50% at a wavelength of 13.5 nm wavelength, but the oxidation of the pellicle according to the invention is much smaller. The filter window can for example be used to separate a Projection Optics box and a wafer compartment of the apparatus or to shield a reticle from particle contamination.
1. A filter window for EUV lithography comprising:
a pellicle comprising a first layer and a second layer on top of the first layer, wherein the first layer comprising a material selected from the group consisting of AlN, Ru, Ir, Au, SiN, Rh, and combinations thereof, and wherein the second layer includes elevated bars; and
a wire structure configured to support said pellicle.
2. A filter window according to claim 1 , wherein a thickness of said pellicle is between about 30 nm and about 300 nm.
3. A filter window according to claim 2 , wherein a thickness of said pellicle is between 30 nm and 100 nm.
4. A filter window according to claim 1 , wherein said pellicle comprises a third layer arranged on top of the second layer.
5. A filter window according to claim 4 , wherein said third layer comprises a material selected from the group consisting of AlN, Ru, Ir, Au, SiN, Rh, C and combinations thereof.
6. A filter window according to claim 1 , wherein said second layer comprises a material selected from the group consisting of Si, Be, B 4 C, Mo, Zr, Nb, C, Al and combinations thereof.
7. A filter window according to claim 1 , wherein said elevated bars comprise Si.
8. A filter window according to claim 1 , wherein said bars have a pitch between 500 and 5000 nm and each bar has a height between 200 and 500 nm.
9. A filter window according to claim 1 , wherein said wire structure comprises metal wires, the distance between said wires, in at least one direction, being of the magnitude of millimeters.
10. A filter window according to claim 1 , wherein the first layer of the pellicle includes C.
11. A lithographic projection apparatus comprising:
an illumination system configured to condition a beam of radiation;
a mask table provided with a mask holder configured to hold a mask;
a substrate table provided with a substrate holder configured to hold a substrate;
a projection system configured to image an irradiated portion of the mask onto a target portion of the substrate, and
a filter window comprising:
a pellicle having a first layer and a second layer on top of the first layer, wherein the first layer comprising a material selected from the group consisting of AlN, Ru, Ir, Au, SiN, Rh and combinations thereof and wherein the second layer includes elevated bars; and
a wire structure configured to support said pellicle.
12. A lithographic projection apparatus according to claim 11 , wherein each wire of said wire structure is arranged such that each wire has at least a component perpendicular to a scan direction of said projection apparatus.
13. A lithographic projection apparatus according to claim 11 , wherein said filter window is arranged to separate a projection optics box from a wafer compartment of said apparatus.
14. A lithographic projection apparatus according to claim 11 , wherein said filter window is arranged to shield a reticle from particle contamination.
15. A lithographic projection apparatus according to claim 11 , wherein the first layer of the pellicle includes C.
16. A device manufacturing method comprising:
patterning a beam of radiation with a pattern in its cross section;
projecting the patterned beam of radiation onto a target portion of a layer of radiation sensitive material on a substrate, and
filtering the beam of radiation using a filter, the filter including a pellicle comprising a first layer and a second layer on top of the first layer, wherein the first layer comprising a material selected from the group consisting of AlN, Ru, Ir, Au, SiN, Rh, and combinations thereof and wherein the second layer includes elevated bars, and a wire structure for supporting said pellicle.
17. A device manufactured in accordance with the method of claim 16 .
18. A device manufacturing method according to claim 16 , wherein the first layer of the pellicle includes C.