Plasma Parameter Dependence of CriticalParticle Size at the Moment of Void Formationin RF Silane Plasmas

摘要

Although dust-free voids are frequently observed in many dusty plasmas, experimentsregarding the critical particle size for the void formation have not been reported much. In thiswork, the dust particle size measurement at the critical moment of the void formation wasperformed by the polarization-sensitive laser light scattering method (PSLLS) as the input rfpower was varied in the silane plasmas in which particles were created and grown. The electrontemperature and ion density were also measured by a floating probe', and the relation betweenthe parameters was studied. The results show that the critical particle size was decreased from50 nm to 35 nm as the rf power was increased from 30 W to 100 W. In addition, the electrontemperature and ion density were increased from 4.7 eV to 6.2 eV and from 7.0X10' cm-3 to1.4 x1010 cm 3, respectively. To investigate the mechanism of the void formation, we calculatedthe critical particle size for the void with measured plasma parameters using a simple one-dimensional force balance equation along the horizontal direction (parallel to the electrode).Consequently, the calculated particle sizes were in good agreement with the measured ones.