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2000
Journal Article
Titel
Pinch plasma radiation source for extreme ultraviolet lithography with a kilohertz repetition frequency
Abstract
An extreme-ultraviolet radiation source based on a xenon pinch plasma is discussed with respect to the demands on a radiation source for extreme-ultraviolet lithography. Operation of the discharge in a self-igniting-plasma mode and omitting a switch permits a very effective and low-inductive coupling of the electrically stored energy to the electrode system. The xenon plasma exhibits broadband emission characteristics that offer radiation near 11 and 13 nm. Both wavelengths are useful in combination with beryllium- and silicon-based multilayer mirrors. The plasma emits approximately 74 mW/sr at 11.5 nm and 40 nW/sr at 13.5 nm in a bandwidth of 2 per cent when operated at a repetition frequency of 120 Hz. The source size is less than 500 mu m in diameter (FWHM) when viewed from the axial direction. The pulse-to-pulse stability is better than 3.6 per cent. First results with a repetition rate of as much as 6 kHz promise the possibility of scaling to the required emission power for extreme-ultraviolet lithography.