Role of Energy‐Dependent Secondary Electron Emissions in Nonlinear Amplification of Plasma Density in Capacitive RF Discharge for Surface Processing

We investigate how energy‐dependent surface reactions control electron heating and density amplification in capacitively coupled Ar plasmas using a two‐dimensional particle‐in‐cell simulation. The electron emission coefficients at the surface depend explicitly on the incident ion and electron energies, leading to strong nonlinear amplification of the electron density, especially for dual‐frequency waveforms. Phase‐resolved energy distribution functions and current densities show that high‐energy electrons created by ion‐induced emission at one electrode efficiently trigger electron‐induced secondary emission at the opposite electrode. The temporally asymmetric sheaths create a feedback loop that enhances ionization, thereby increasing the overall electron density without altering the basic transport. The results suggest that managing secondary‐electron emission can be effectively leveraged to tailor plasma density profiles in practical process reactors.