Kinetic Modeling of Breakdown Phenomena in Narrow Gaps for Advanced Plasma Processing

Inductively or capacitively plasma sources used for crucial material processing, such as etching in the semiconductor industry, suffer from undesired breakdown within the existing cylindrical narrow gaps of the plasma chamber. Such breakdowns reduce the reactor lifespan and compromise the wafer processing quality. Capitalizing on a previous study [1], this work elucidates the detailed mechanism of such breakdowns that can occur in a complex showerhead configuration. Specifically, it is found that electron-induced secondary electron emissions predominantly trigger and maintain the breakdown, and a detailed knowledge of the yield at low energy is required. Additionally, the results show that the presence of the background plasma in the reactor leaking into the gap facilitates breakdown events. Based on this new understanding, mitigation strategies are proposed. The investigation is performed using the explicit and cylindrical version of EDIPIC-2D, an open-source Particle-In-Cell specialized in the modeling of low-temperature plasmas.