Fourier transform infrared study of thermally grown SiO2in the presence of 1,1,1, trichloroethane

Gate oxides for metal‐oxide–semiconductor devices have been grown in presence of 1,1,1, trichloroethane (TCA) as a chlorine source for passivation. Infrared absorption was studied in these oxides and results were compared with oxides grown in presence of trichloroethylene (TCE) under identical conditions to assess the feasibility of substituting a TCA source for TCE. It is found that the stoichiometry of these oxides is not affected by the type of chlorine source, i.e., TCA or TCE. However, based on this study a different reaction mechanism for TCA or TCE oxides is proposed wherein C2H4 is also a byproduct in addition to well known HCl, Cl2, CO2, and H2O. Furthermore, Si—OH deformation observed in the infrared transmission (IR) spectra at 880 cm−1 is held responsible for passivation of interface states, i.e., tying up of dangling Si bonds at Si—SiO2 interface. A modified structural model is proposed for these oxides, which could account for all the observed IR vibrations.