Emission from a gas puff target irradiated with a Nd:YAG laser for EUV and x-ray lithography

Soft x-ray and extreme-UV emissions form plasmas produced using a gas puff target irradiated with a Nd:YAG laser has been investigated. The use of the gas puff targets, create by pulsed injection of high-density gas through a nozzle, eliminates the production of debris associated with solid targets. Laser pulses of either 0.9 ns or 10 ns time duration with energies up to 0.7 J were used to produce plasmas. Emissions in the 1-22 nm wavelength range from laser-produced gas puff plasma were characterized for various gases. The spectral measurements were performed with the use of grating spectrographs equipped with the back- illuminated CCD camera. The source sizes was measured using the Fresnel zone plate imaging system and the grating spectrograph equipped with a slit placed perpendicularly to the dispersion direction. The obtained results would allow to develop an efficient and debrisless laser-produced radiation source for applications in proximity x-ray lithography and extreme UV lithography technologies.