A compact, quasi-monochromatic laser-plasma EUV source based on a double-stream gas-puff target at 13.8 nm wavelength

A compact, high-repetition table-top EUV source, based on a gas-puff target, is presented. This source was developed in our group and is capable of emitting quasi-monochromatic radiation at 13.8 nm wavelength with the inverse relative bandwidth of 140 and pulse energies up to similar to 1.3 mu J/pulse at 10-Hz repetition rate. The source is debris-free, operates near the lithographic wavelengths and offers the energy density of similar to 0.4 mJ/cm(2) in each EUV pulse. These three features make the source attractive for lithographic experiments. The timing optimization of the source, its energy per pulse, spectral and spatial distributions are pointed out in detail as well as the enhancement in energy density achievable with a multi-layer collector mirror compared to a planar mirror of equal reflectivity.