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

以放电频率为参数，在几纳米以上的尺寸范围内研究了硅烷射频放电中颗粒生长过程与放电频率的关系。一系列实验结果表明：在所有放电频率下，射频电极在等离子体/鞘层边界周围形成粒子并生长；在一定功率下，随着放电频率的增加，颗粒在快速生长阶段的生长速率降低，但由于颗粒密度的增加，在放电开始后颗粒的生长开始提前；-10nm大小的粒子的密度与离子的密度相当甚至更高，因此它们几乎都是中性的。这些结果不能用传统的热凝聚模型来解释，这表明在中性粒子的快速生长过程中，大于10 eV的高能电子对电离部分中性粒子起了重要作用。为了恰当地解释这些实验特征，提出了一个粒子凝聚模型。

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.