Modeling the Role of Secondary Electron Emission in Direct Current Magnetron Sputtering using Explicit Energy-Conserving Particle-in-Cell Methods

TL;DR

This paper uses advanced particle-in-cell simulations to study how secondary electron emission affects plasma behavior in direct current magnetron sputtering, highlighting the advantages of an energy-conserving algorithm.

Contribution

The study introduces an explicit energy-conserving PIC algorithm and compares its performance with standard methods in modeling dcMS discharges.

Findings

Higher secondary electron yield increases plasma current and density.

Lower external resistance results in larger currents and smaller voltages.

Energy-conserving PIC shows improved stability at higher plasma densities.

Abstract

We present results from a fully kinetic particle-in-cell (PIC) simulation of direct current magnetron sputtering (dcMS) in a 2D cylindrically symmetric geometry. The particle-in-cell model assumes an electrostatic approximation and includes the Monte Carlo collision (MCC) method to model collisions between electrons and the neutral gas. A newly-implemented explicit energy-conserving PIC algorithm (EC-PIC) is also exercised by the model and results are compared with the standard momentum conserving PIC (MC-PIC) method. We use these simulation tools to examine how changes in secondary electron yield (SEY) and the external circuit impact the steady-state current, voltage, and plasma density of dcMS discharges. We show that in general, higher SEY and lower external resistance values lead to larger currents, smaller voltages, and larger plasma densities. We demonstrate that EC-PIC is superior to MC-PIC as the plasma current and density increase due to the improved numerical stability provided by EC-PIC.