Hazards of dichlorosilane exhaust deposits from the high-temperature oxide process as determined by FT-ICR mass spectrometry

Gas samples from the exhaust system of tools employing dichlorosilane (DCS) in high temperature oxide (HTO) deposition that produced flammable solid deposits have been analyzed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Exact mass determinations by the high-resolution FT-ICR allowed the identification of various polysiloxane species present in such an exhaust flow. Ion-molecule reactions of dichlorosilyl cation with water and DCS indicate the preferred reaction pathway is disiloxane formation through HCl loss, a precursor to the highly flammable polysiloxanes that were identified in the gaseous exhaust and in exhaust deposits. Minimization of these hazardous deposits is discussed with respect to water contamination, dilution factor and water scrubbing of the HTO exhaust.