Impurities in monosilanes synthesized by different processes

Using high-resolution IR spectroscopy, we have compared the impurity compositions of monosilane (SiH4) fractions enriched in impurities in the process of cryofiltration and low-temperature distillation of monosilanes derived from silicon tetrafluoride (SiF4) and trichlorosilane (SiCl3H). The results demonstrate that the more volatile impurities present in both monosilanes are methane (CH4) and carbon dioxide (CO2), whereas the impurities specific to the fluoride-derived monosilane are SiF4, SiF3H, and SiF2H2. The less volatile impurities common to both monosilanes are ethane (C2H6), disiloxane (Si2H6O), and disilane (Si2H6); the impurities specific to the fluoride-derived monosilane are tetrafluoroethylene (C2F4) and monofluorosilane (SiFH3); and those specific to the chloride-derived monosilane are hydrogen chloride (HCl) and the chlorosilanes SiClH3, SiCl2H2, and SiCl3H.