Analysis of the production of the CH(A2Δ) state from the dissociative excitation of tetramethylsilane in the electron-cyclotron resonance plasma of Ar: The H2O-addition method

The dissociative excitation reaction of Si(CH3)4 with the electron-cyclotron resonance plasma of Ar was investigated by the optical emission spectroscopy of CH(A2Δ-X2Π) transition and electrostatic-probe measurements. The density ne and the temperature Te of free electrons were controlled by adding a trace amount of H2O vapor externally into the reaction region, and the dependence of the CH(A2Δ-X2Π) emission intensity on the addition of H2O was observed for comparison with the dependences evaluated on the basis of ne and Te. The mechanism of the production of CH(A2Δ) was found, predominantly, to be electron impact processes for producing CH(A2Δ) + Si(CH3)3 + H2 and CH(A2Δ) + Si(CH3)2 + CH4 + H. In the H2O-adddition method employed in this study, the dominant processes can be distinguished from others if the differences in their threshold energies from those of other processes are larger than 3 eV.