Equilibrium and relaxation of particulate charge in fluorocarbon plasmas

Abstract

Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet J. Appl. Phys. 112, 123302 (2012) Charging effect simulation model used in simulations of plasma etching of silicon J. Appl. Phys. 112, 084308 (2012) Extraction of negative ions from pulsed electronegative capacitively coupled plasmas J. Appl. Phys. 112, 033303 (2012) High electronegativity multi-dipolar electron cyclotron resonance plasma source for etching by negative ions J. Appl. Phys. 111, 083303 (2012) Decreasing high ion energy during transition in pulsed inductively coupled plasmas Appl. Phys. Lett. 100, 044105 (2012) Additional information on J. Appl. Phys. Charging of micron-size particulates, often appearing in fluorocarbon plasma etching experiments, is considered. It is shown that in inductively coupled and microwave slot-excited plasmas of C 4 F 8 and Ar gas mixtures, the equilibrium particle charge and charge relaxation processes are controlled by a combination of microscopic electron, atomic ͑Ar ϩ and F ϩ ͒, and molecular ion ͑CF 3 ϩ , CF 2 ϩ , and CF ϩ ͒ currents. The impact of molecular ion currents on the particulate charging and charge relaxation processes is analyzed. It is revealed that in low-power ͑Ͻ0.5 kW͒ microwave slot-excited plasmas, the impact of the combined molecular ion current to the total positive microscopic current on the particle can be as high as 40%. The particulate charge relaxation rate in fluorocarbon plasmas appears to exceed 10 8 s Ϫ1 , which is almost one order of magnitude higher than that from purely argon plasmas. This can be attributed to the impact of positive currents of fluorocarbon molecular ions, as well as to the electron density fluctuations with particle charge, associated with electron capture and release by the particulates.

Charging and trapping of macroparticles in near-electrode regions of fluorocarbon plasmas with negative ions

“…10,11 Furthermore, it has recently been demonstrated that in the bulk of C 4 F 8 ϩAr inductively coupled and surface wave sustained plasmas positive fluorocarbon ions can significantly affect the macroparticle charging and charge relaxation processes. 12 In this article, we consider the effect of negative ions on particulate charging and trapping in the near-electrode region of fluorocarbon plasmas. We assume that the charge proportion on negatively charged dusts is low, and the particulates do not affect the structure of the sheath/presheath region.…”

Incorporation of Dust Particles into a Growing Film During Silicon Dioxide Deposition from a TEOS/O2Plasma

“…Five thousand particles are statistically sufficient for this purpose, since a larger number had no significant effect on the results. The time step is chosen in such a way that it is greater than the characteristic charging time (Ostrikov et al 2001) and less than the time scale for fluctuations . Hence, the time-average properties of the local sheath field can be used during the calculation of particle trajectory after it departs from its equilibrium position.…”

Effect of ion beam current on dust charge fluctuations and ion-acoustic waves in electronegative dusty plasmas

“…The presence of additional negative ions can be considered as another plasma component which are heavier than that of electrons and such plasma exhibits quite novel properties than the ordinary dusty plasma. The presence of negative ions in an ordinary dusty plasma has a considerable effect on the evolution of dust surface potential and dust charging process [24], and consequently it affects the wave phenomenon and sheath formation in the vicinity of material surface [25,26]. Therefore, the understanding of electronegative dusty plasma is important in various fields such as industrial plasma processing and space environments [25][26][27][28].…”