硅薄膜沉积中等离子体辉光功率和阻抗的测试分析

Plasma power and impedance measurement in silicon thin film deposition

采用改进的电压和电流测试方法对衬底电极外加不同电压Vs的射频等离子体中的阻抗和功率消耗进行了测试分析.结果表明:在射频电极施加恒定的电压Vel时,随衬底电极外加电压Vs的增加,辉光的电流在增加,结果导致阻抗在减小;另外,通过计算分析发现:仅有一小部分功率用于辉光,大部分功率消耗在匹配器和电缆上.通过对等离子体电学特性的综合测试分析也说明:在保证有足够多的硅烷时,衬底电极外加电压Vs增加时将会提高薄膜的沉积速率.

Plasma impedance and power consumption were measured by modified voltage-current method at different applied voltages on the substrate electrode. The results indicated that discharge current increases with the increase of applied voltage on the substrate electrode when the applied voltage of RF electrode is fixed. As a result, plasma impedance decreases. In addition, only a small part of power was used by the plasma and a large part of power was consumed on the matching network and cables. Through the analysis of plasma electrical properties, it was found that the deposition rate of thin films will be increased with the increase of applied voltage on the substrate electrode so long as there is enough silane.