On the physics of a large CCP discharge

Abstract

Demands of the plasma processing industry gradually lead to an increase in electrode areas and driving frequency of the commonly used capacitively coupled reactors. This brings about new phenomena which differ from the well known physics of smaller capacitively coupled plasma (CCP) devices. In this work we compare experimental data and results of numerical modeling for a large CCP discharge having a GEC celllike geometry currently studied in context of a possible use as a sputtering device. Using an electrostatic implicit particlein cell code with MonteCarlo collisions (PIC/MCC), we have been capable of reproducing all main features of the experimental discharges, which have strong relevance for the processing applications, such as the plasma uniformity and the selfbias. The side chamber proves to play an essential role in defining the physics of the whole device, featuring substantial production of plasma particles and participating in establishing the selfbias due to the telegraph effect observed for higher frequencies.

Observations of Surface Mode Influence on Plasma Uniformity in PIC/MCC Simulations of Large Capacitive Discharges

“…That work demonstrated reasonable agreement between results of the analytical and the numerical models, which indicated resonant excitation of the quasi‐symmetric (also referred to as “the standing wave” in the literature) surface modes during the driving frequency scan. In addition, the powered electrode and the grounded electrode sheath widths tended to be approximately equal for higher driving frequencies in agreement with ref …”

“…In addition, the powered electrode and the grounded electrode sheath widths tended to be approximately equal for higher driving frequencies in agreement with ref. [19] The present work comlements other studies of the physics of large scale CCP discharges with the particle-incell approach. [20][21][22] By following the time evolution of the plasma À field system (in the present work we have used the electrostatic approximation for the field description) in the time domain self-consistently, this approach treats the plasma sheaths in a fully nonlinear manner.…”

“…In case when the blocking capacitor is absent (such as in the setup considered in the present work), the dc plasma potential is approximately equal to the rf sheath voltage amplitude at the edge of the powered sheath. If one has a grounded side‐chamber and a blocking capacitor, the physics leading to establishment of the self‐bias is more complicated and can result in vanishing of the self‐bias if the damping is large (e.g., at higher driving frequencies) . From the above discussion, it is clear that only asymmetric electric field can lead to emergence of the self‐bias.…”

“…The particle‐in‐cell approach used in this work is conceptually similar to the one employed in ref . However, because of Cartesian geometry adopted in the present work we dispense with the adaptive particle management and use constant weight for all superparticles.…”

The 2017 Plasma Roadmap: Low temperature plasma science and technology

“…Adoption of state-of-the-art of high-performance computing (HPC) techniques is still a challenge in the LTP field. There is encouraging progress in AMR, graphical-processing-units (GPUs) [171], hybrid techniques and conventional parallelization, though implementation of Poisson's equation, due to its nonlocal nature, makes it still a major challenge to code parallelization. Most of the widely used CC, CWO and OSS modelling platforms are general frameworks intended to address a variety of problems, which may conflict with the specialization required for state-of-the-art HPC methods.…”