Conversion efficiency of laser radiation into soft x-ray radiation of laser produced plasmas for x-ray lithography

Laser radiation pulses with energies between .4 and 3 joules producted by a Nd:YAG/glass system at 1064 nm and 532 nm have been focussed onto steel targets to produce intense soft x-ray radiation pulses and expose an FBM 120 resist coated wafer behind a gold patterned 2 micrometers silicon mask. The sensitivity of the resist was determined by an exposure to a known dose of synchrotron radiation. A conversion efficiency of 3.4% at 1064 nm and 3 joules and 5.0% at 532 nm and 1.2 joules has been found.