A multi-kilohertz pinch plasma radiation source for extreme ultraviolet lithography

A pinch plasma source in the extreme ultraviolet is presented where the special design of the electrodes leads to advantages concerning low erosive operation and an effective coupling of the electrically stored energy to the electrode system. Most promising results of the source parameters with respect to the demands for extreme ultraviolet lithography are achieved when operating with xenon. Intense emission around 11 nm and 13 nm is observed. The plasma column has a diameter of less than 500 µm when viewed from the axial direction. The electrode design allows for an accessible solid angle of around pi sr. The shot-to-shot stability is better than 4 % (rms). A maximum output of 0.8 mJ /(sr 2 % bw) at 13.5 nm has been observed with an input pulse energy of 2 J. Operation at a repetition rate of 1 kHz and an electrical input power of 2 kW has been demonstrated with an average emitted power of around 0.3 W/(sr 2 % bw). Approaches of power scaling into the range which is desired for EUVL will be discussed.