Optimization of x-ray sources for proximity lithography produced by a high average power Nd: glass laser

We measured the conversion efficiency of laser pulse energy into keV x rays from a variety of solid planar targets and a Xe gas puff target irradiated using a high average power Nd:glass slab laser capable of delivering 13 ns full width at half-maximum pulses at up to 20 J at 1.053 μm and 12 J at 0.53 μm. Targets were chosen to optimize emission in the 10-15 Å wavelength band, including L-shell emission from materials with atomic numbers in the range Z=24-30 and M-shell emission from Xe (Z = 54) With 1.053 μm a maximum conversion of 11% into 2π sr was measured from solid Xe targets At 0.527 μm, ;efficiencies of 12%-18%/(2π sr) were measured for all of the solid targets in the same wavelength band. The x-ray conversion efficiency from the Xe gas puff target was considerably lower, at about 3%/(2π sr) when irradiated with 1.053 μm.