A semi-analytical RF sheath model for a wide range of excitation waveforms and amplitudes, and levels of collisionality

The behavior of radio frequency-driven capacitively coupled plasmas (RF-CCPs) is largely influenced by the characteristics of the boundary sheath, a thin electron-depleted layer that forms in front of electrodes and walls. The sheath plays a crucial role in governing the transport of ions and electrons across the interface, as well as the distribution of plasma species within the discharge.

The sheath is also an important factor in determining the level of plasma heating, which can have a significant impact on the overall plasma behavior, including the plasma density, ion energy distribution, and the formation of reactive species. Therefore, developing accurate models of the sheath is of both theoretical and practical interest for understanding and controlling the behavior of RF-CCPs in various applications.

This contribution will present a semi-analytical RF sheath model for a wide range of excitation waveforms and amplitudes, and levels of collisionality. It is based on the smooth step model (SSM), a recently developed approximate solution of the Poisson-Boltzmann equation which overcomes the limitations of the Godyak hard step model.