Soft x-ray spectral radiations from Xe,H2O,andCO2cryogenic targets irradiated by a 1 &mgr;m neodymium doped YAG-slab laser at pulse widths of 12–20 ns and at laser intensities of5×1010–1012 W/cm2have been observed. These targets radiate soft x-rays in a wavelength range of 10–13 nm which is useful for projection microlithography. We have found a strong x-ray spectral peak at&lgr;=10.8 nmwith a Xe cryogenic target. The measured x-ray conversion efficiency with the Xe target was0.8&percent;/sr(&lgr;=10.8±0.27 nm)at a laser intensity of1×1012 W/cm2.This was ten times or more efficient than that withH2OandCO2targets. ©1998 American Institute of Physics.