Growth kinetics and behavior of dust particles in silane plasmas

Growth kinetics and behavior of dust particles in silane plasmas are studied using a new method combining an rf discharge modulation technique with two laser light scattering techniques. From the experiments, the following results are obtained: dust particles tend to be sustained around plasma/sheath boundaries near electrodes, especially the rf electrode; dust particles of a larger size exist in a lower space potential region near the rf electrode; dust size and density amount to 60-180 nm and 10⁸-10⁹cm^-3in 1-2 s after the rf-power-on. The dust growth rate, which is high compared to the film deposition rate, can be explained by taking into account the contribution of positive-ion and/or neutral radical fluxes. The dust-trapping around the boundary can be explained by the balance between the electrostatic force and the ion drag force exerting on the particle. The effects of gas flow on dust motion and a dust suppression mechanism for rf modulated discharges are also discussed.