Study on effect of discharge frequency on particle growth in high frequency plasma.

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Discharge frequency dependence of growth processes of particles in silane rf discharges have been studied in a size range above a few nanometers as parameters of discharge frequency. A seies of experiments have given the following results : particles nucleate and grow around the plasma/sheath boundary by the rf electrode for all discharge frequencies ; increasing the discharge frequency under a constant power, a growth rate of particles in the rapid growth phase decreases, while they begin to be observed earlier after the discharge initiation due to the increase in their density ; a density of particles of -10nm in size is comparable to or even higher than that of ions, and hence almost of them are neutral. These results can not be explained by the conventional thermal coagulation model, suggesting that high energy electrons above several 10's eV play an important role to ionize a part of neutral particles in their rapid growth. In order to explain properly most of these exprimental features, a particle coagulation model is proposed.