In this article, we present a theoretical and experimental study of the x‐ray emission produced by laser plasma sources in different spectral ranges appropriate for x‐ray lithography either in proximity printing (XRL) or projection (XRPL) approaches. For XRPL application, experiments using 10 ns laser pulses show that the maximum conversion efficiency in the (80–250 eV) range is attained atI=1011W cm−2whereas for 25 ns pulses andI≤6×1011W cm−2, it is still increasing with laser intensity. On the other hand, higher laser intensities are required to obtain a high conversion efficiency for XRL (0.9–1.4 keV). Efficient emission peaked at 1.1 keV can be achieved forI≥1013W cm−2with copper targets and pulse duration shorter than 5 ns. For iron line emission (peak at 0.9 keV), the laser intensity can be lower (I=5×1012W cm−2) and the pulse duration longer (τp=10 ns). Finally, we discuss the different approaches which may lead to the appropriate laser design.