FTIR plasma phase analysis of hexamethyidisiloxane discharge in microwave multipolar plasma at different electrical powers

In this paper, the gas phase composition of hexamethyldisiloxane (HMDSO) microwave plasma at 4 x 10(-3) mbar and of the Corresponding films were studied by FTIR spectroscopy under different power conditions. At low powers, species with a chemical structure very similar to that of HMDSO were observed in the gas phase, whereas the film essentially contained short -[(CH3)(2)SiO](n)-like chains with a low branching rate and the end group -Si(CH3)(3). At higher powers, the chemical entities present in the gas phase contained several -(Si-O)(x)- bonds, whereas the branching rate in the film increased with the amount of Si-H, Si-C and Si-O bonds. The interpretation of these observations led to a proposal involving a chemical mechanism. In this mechanism, the increasing decomposition of HMDSO into by-products, which themselves increasingly decompose as the power is raised, plays a determining role.