Particle-free thin film deposition from acetylene and silane precursors using atmospheric plasma vacuum ultraviolet radiation

Abstract We present a study on photon-initiated thin film deposition by separating vacuum ultraviolet (VUV) radiation produced by atmospheric helium plasma from a precursor gas using a windowless setup. Acetylene (C2H2) and silane (SiH4) were selected as high electron affinity precursors with a strong tendency to form particles during plasma-based deposition. The VUV radiation from the plasma enabled dust-free deposition of homogeneous thin films from both precursors. Films were analyzed by Fourier-transform infrared spectroscopy, while the strong ionic contribution to film formation has been studied by positive ion mass spectrometry. We found profoundly different trends for film absorbance and relative abundances of ionic species identified as growth precursors with admixture for the two precursors and a strong influence of solvent and impurity species.