Arcing phenomenon in RF discharge

Abstract

Arcing phenomenon was investigated in RF capacitively coupled plasma. The main arcing observed in this study can be categorized into the micro arcing which is considered as the breakdown of the sheath or the dielectric because the other arcing modes are less likely to occur. To explain the sheath breakdown, we apply Towndsend theory to the sheath in RF discharge. That describe the sheath breakdown well and roughly estimates the arcing-occurring voltage. The (solid) dielectric breakdown is caused by the sheath breakdown. Therefore, the sheath breakdown must be prevented to protect originally the arcing. Factors to determine arcing frequency are dielectric strength and applied electric field. It was found that the voltage depth of arcing peak means degree of breakdown, and is proportional to sheath voltage. The increase of plasma potential is the main mechanism to occur the arcing. The sheath voltage increased by plasma potential, increasing the electric field in sheath, make arcing condition. Roughness is critical factor to occur arcing in arcing-avoiding condition. By anodizing the electrode, both the arcing frequency and the peak depth are diminished because the electric field in sheath is increased. To avoid the arcing, it is needed to estimate the arcing voltage and to measure the plasma potential and to remove the dielectric deposited on surface by cleaning.