Investigation of low temperature plasmas induced using laser-produced plasma EUV sources

Abstract

Low temperature plasmas induced by irradiation of molecular gases with extreme ultraviolet (EUV) pulses were studied. The EUV pulsed beams of high intensity, were formed using laser-produced plasma (LPP) sources, based on Nd:YAG laser systems and a double-stream Xe/He gas-puff target. The EUV beams were used for irradiation of small portions of gases, injected into a vacuum chamber synchronously with the radiation pulses. Low temperature plasmas produced this way in oxygen, nitrogen or sulfur hexafluoride gas emitted radiation in a wide spectral range. The corresponding EUV spectra were dominated by emission lines originating from singly charged, atomic ions. In case of spectra recorded in an optical range, emission lines, corresponding to radiative transitions in atomic or molecular species, were detected. Taking into account a Stark broadening of F I emission lines an electron density was estimated. Its value exceeded 1017cm-3, which is a few orders of magnitude higher comparing to plasmas produced in standard generators. Employing the SF6 – based plasmas an experiment concerning plasma treatment of a silicon surface was performed. A possibility to create different kinds of nanostructures was demonstrated.