AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Monday Sessions
       Session PS2-MoA

Invited Paper PS2-MoA1
Tailored Ion Energy Distributions on Plasma Electrodes

Monday, October 29, 2012, 2:00 pm, Room 25

Session: Plasma Modeling
Presenter: P. Diomede, University of Houston
Authors: P. Diomede, University of Houston
D.J. Economou, University of Houston
V.M. Donnelly, University of Houston
Correspondent: Click to Email
Control of the energy of ions bombarding a substrate is important for both plasma etching and deposition. As device dimensions keep shrinking, requirements on selectivity and substrate damage become ever more stringent. Such requirements impose strict limits not only on the mean ion energy but also of the ion energy distribution (IED). The IED may be controlled by applying judicious bias voltage waveforms on the substrate, or on a “boundary electrode” in contact with the plasma. A Particle in Cell simulation with Monte Carlo Collisions (PIC-MCC) was employed to predict the IEDs resulting by the application of a variety of voltage waveforms (steps, staircases , etc.) on a plasma electrode in the afterglow of power-modulated plasmas. IEDs with distinct energy peaks at controlled location, spacing, and fraction of ions under each peak, were obtained by properly selecting the applied waveform. The effect of gas pressure on the IEDs was also studied. A semi-analytical equivalent-circuit model was developed to solve the “inverse problem”, i.e., to find the voltage waveform that results in a desired IED. The model allowed rapid calculation of the IED, and model predictions were in agreement with experimental data and the results of the much more computationally intensive PIC simulation. Work supported by DoE Plasma Science Center and NSF.