Compact electron-based extreme ultraviolet source at 13.5 nm

摘要

Generation of extreme ultraviolet (EUV) radiation from solid targets is studied and a compact EUV source for small-scale lithographic applications and EUV metrology is developed. This source is based on a transfer of conventional x-ray tube technology into the EUV spectral range. As in an ordinary x-ray tube, electrons are generated by a tungsten filament and accelerated in a high-voltage electric field towards a solid target. In the demonstrated "EUV tube" beryllium and silicon targets are used to generate radiation at 11.4 nm and 13.5 nm, respectively. The absolute conversion efficiencies into EUV photons are measured. At 13.5 nm an EUV power of 34 μW or 2x10~(12) photons/s (in 2% bandwidth and a solid angle of 2π sr) is demonstrated. Prospects for a further power scaling of the EUV source are discussed.