Arrangement for generating EUV radiation
View Patent ↗The invention is directed to an arrangement for generating EUV radiation particularly for source modules in exposure installations for EUV lithography for semiconductor chip fabrication. The object of the invention, to find a novel possibility for realizing an EUV source module which appreciably improves the ratio of resources to results in the transfer of radiation from the primary source location (plasma 3 ) to the secondary source location (output opening ( 6 ) of the source module ( 1 )/intermediate focus plane ( 62 )), is met according to the invention in that the plasma ( 3 ) is formed as a volume emitter for direct illumination of the output opening ( 6 ) without collector optics ( 5 ), and the transverse dimension (d) of the plasma ( 3 ) is greater than the diameter (D) of the output opening ( 6 ), wherein the extent to which the diameter is exceeded depends on the distance (L) between the plasma ( 3 ) and the output opening ( 6 ) and on the numerical aperture (NA) of the illumination system downstream.
1. An arrangement for the generating of EUV radiation, comprising:
a plasma generation arrangement for generating a spatially definitely limited hot plasma having a transverse dimension d and defining a location of a primary source illumination, the plasma generation arrangement located in a vacuum chamber;
the vacuum chamber having an optical axis and an output opening for defining a location of a homogeneously illuminated secondary source for an exposure system located downstream from the output opening along the optical axis, the output opening having a diameter D; and
at least one debris filter arranged between the plasma and the output opening,
wherein the plasma is formed as a volume emitter for direct illumination of the output opening without collector optics, the transverse dimension d of the plasma being greater than the diameter D of the output opening, and
wherein the difference between d and D depends on a distance L between the plasma and the output opening, and on a numerical aperture NA of the illumination system located downstream from the output opening along the optical axis.
2. The arrangement according to claim 1 , wherein the plasma is an EUV-emitting plasma having the transverse dimension d of ≈(D+2L*NA).
3. The arrangement according to claim 1 , wherein the plasma is an EUV-emitting plasma formed as a gas discharge plasma at an electrode arrangement in the vacuum chamber.
4. The arrangement according to claim 3 , wherein the EUV-emitting plasma is generated in the gas volume between an anode and a cathode of the electrode arrangement.
5. The arrangement according to claim 4 , wherein the cathode is formed as a cylindrical or slightly conical hollow cathode, and the anode is a ring electrode which is mounted downstream from the cathode along the optical axis in the direction of the output opening.
6. The arrangement according to claim 3 , wherein the EUV-emitting plasma is generated as a sliding discharge on an insulator.
7. The arrangement according to claim 6 , wherein the cathode is constructed as a center electrode around which the insulator in a tubular form and the anode are arranged substantially coaxially, and wherein the discharge is carried out at the front side of the electrode arrangement radially along a surface of the insulator.
8. The arrangement according to claim 6 , wherein the insulator is made of a material with a high relative permittivity, such as lead zirconate titanate (PZT), lead boron silicate, or lead zinc boron silicate.
9. The arrangement according to claim 6 , wherein the insulator is made from a highly-insulating ceramic such as Si 3 N 4 , Al 2 O 3 , AlZr, AlTi, BeO, SiC, or sapphire.
10. The arrangement according to claim 1 , wherein the EUV-emitting plasma is generated by high-frequency excitation.
11. The arrangement according to claim 10 , wherein the EUV-emitting plasma is generated by electron cyclotron resonance excitation (ECRH).
12. The arrangement according to claim 1 , wherein the EUV-emitting plasma is generated by electron cyclotron resonance excitation (ECRH).
13. An arrangement for generating EUV radiation, comprising:
a plasma generation arrangement for generating a spatially definitely limited hot plasma having a transverse dimension d and defining a location of a primary source illumination, the plasma generation arrangement located in a vacuum chamber;
the vacuum chamber having an optical axis and an output opening for defining a location of a homogeneously illuminated secondary source for an exposure system located downstream from the output opening along the optical axis, the output opening having a diameter D; and
at least one debris filter arranged between the plasma and the output opening;
wherein the plasma is formed as a volume emitter for direct illumination of the output opening without collector optics, the transverse dimension d of the plasma being greater than the diameter D of the output opening;
wherein the difference between d and D depends on a distance L between the plasma and the output opening, and on a numerical aperture NA of the illumination system located downstream from the output opening along the optical axis;
wherein the plasma is an EUV-emitting plasma formed as a gas discharge plasma at an electrode arrangement in the vacuum chamber;
wherein the EUV-emitting plasma is generated in the gas volume between an anode and a cathode of the electrode arrangement;
wherein the cathode is formed as a cylindrical or slightly conical hollow cathode, and the anode is a ring electrode which is mounted downstream from the cathode along the optical axis in the direction of the output opening; and
wherein the debris filter can be switched to function as the anode.