Catalytic decomposition of SiH4 on a hot filament

The products of SiH 4 decomposition on the surface of various filaments were directly detected by using vacuum ultraviolet (VUV) photo-ionization mass spectrometry under collision-free conditions. SiH 2 and SiH 3 were detected at filament temperatures of approximately T f ∼1300 K, where silicide formation on the filament was observed. At higher temperatures, the SiH 2 and SiH 3 signal intensities decreased and Si atom signal increased. It was confirmed that the Si atoms were the main species desorbed from the tungsten filament at T, > 1700 K. H atoms were also detected as a direct desorbed species from the filament by using the [2+1] resonance enhanced multi-photon ionization (REMPI) method combined with time-of-flight (TOF) mass spectrometry. Gas phase chemical reactions of SiH4 with desorbed radicals (Si and H atoms) were also investigated. Si 2 H 6 , Si 2 H 4 and Si 2 could be detected as products of gas phase reactions. A chemical kinetic mechanism starting with Si+SiH 4 and H+SiH 4 reactions was proposed to explain the formation of Si 2 H 6 and Si 2 H 4 .