Compact EUV Mirror Source
Publication Date: 2004-Jan-12
The IP.com Prior Art Database
Daiyu Hayashi, PFL-Aachen
Title: Compact EUV Mirror Source
Author / affiliation: Daiyu Hayashi, Philips Forschungslaboratorien Aachen
The publication relates to the extremely ultraviolet light source comprising a compact mirror plasma source, capable of generating line and continuum x-ray radiation in the wavelength range from the soft (~>10 eV) to hard (~several keV) x-ray. The EUV source consists of one or a couple of super conducting permanent magnets, m-wave power generator, inductively coupled rf heating, or electron beam heating system, and cooling gas flow system. High-density plasmas containing ~10% of hot electrons produced in the mirror magnetic field generates efficiently multi-charged ions (for example,Li+4, Xe+10). They are cooled by the gas flow at the down flow of the plasma, and a recombining plasma is formed. Extremely ultraviolet radiation (~13 nm from Xe+10 ions, or Li+4) are produced in the recombining plasma.
In lithography technologies for silicon-based semiconductor manufacturing, it is an urgent task to develop light sources that are capable of generating extremely ultraviolet (EUV) photons in vacuum environments. The photon intensity (power) required for the lithography system of the next generation is above ~100 W of the 13 nm photons in the wavelength width ~0.5 nm.
For the purpose, EUV light sources utilizing Z-pinch plasmas and those by laser-generated plasmas are the major two schemes currently being developed intensively. In these schemes, plasmas are generated either by applying pulsed high voltage of ~10 kV or by shooting intensive, pulsed laser, in gas atmospheres to be ionized. At this moment, Xe10+ ions are considered to be the best candidate to generate 13-nm-photons by their recombination process. In the ignition phase, a large amount of highly charged ions are produced in plasmas, and they recombine with electrons in the later stage of the discharge, followed by the optical emissions of the EUV photons. Because of the nature of the discharge schemes, both the EUV sources are pulsed light sources. The duration of the EUV photon radiation is at most on the order of ~100 ns. In order to fulfill the requirement mentioned above (ex. ~100 W radiation intensity), the photon energy to be produced per pulse must be as much above ~100 MJ, and for this reason, these technologies currently face a severe problem in increasing the photon intensity up to the required values.
As described above, the currently under-developed EUV light sources have a severe problem in increasing the EUV photon intensity. This can be solved by developing an alternative scheme based on continuous discharge system. This publication is directed on a continuous EUV light source using a compact mirror plasma source.
A compact EUV source equipped with a couple of compact permanent magnets (<10 cm in diameter) and/or superconducting permanent magnets (<5 cm in diameter) (Patent: JP…...