X-ray production ˜ 13 nm from laser-produced plasmas for projection x-ray lithography applications

X-ray production in the region ˜ 13 nm from laser-produced plasmas has been investigated as a source for projection x-ray lithography. The dependence of x-ray conversion efficiency on target material, intensity, and pulse length has been studied by using a 0.53-µm laser with a maximum of 0.3 J. A conversion efficiency of 1% into a 0.3-nm bandwidth has been demonstrated for Sn targets at intensities of ˜ 10(11) W/cm(2) by using a 7.5-ns pulse. Intensity scaling suggests that laser spot size and two-dimensional expansion are important for optimizing x-ray production at these low-irradiation intensities.