Compact electron-based extreme ultraviolet source at 13.5 nm

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 ELIV spectral range. As in an ordinary x-ray tube, electrons are generated by a tungsten filament and accelerated in a high-voltage electric field toward a solid target. In the demonstrated "EUV tube" beryllium and silicon targets are used to generate radiation at 11.4 and 13.5 nm, respectively. The absolute conversion efficiencies into ELIV photons at 13.5 nm are measured. Prospects for a further power scaling of the EUV source are discussed. (C) 2003 Society of Photo-Optical Instrumentation Engineers.