Spatially averaged global model of HBr/Cl₂ inductively coupled plasma discharges

The utilization of HBr/Cl₂ mixed gas discharge in semiconductor etching processes has been a subject of analysis both experimentally and through simulations to understand its discharge characteristics. In this study, we have developed a model that extends the previous global model of the HBr/Cl₂ plasma. The electron temperature and densities are solved in a self-consistent manner, while previous global model uses the measured electron temperature and electron density. Additionally, we have included further data on electron collision reactions to enhance accuracy. This model was then compared with experimental results obtained from pure HBr, pure Cl₂, and HBr/Cl₂ plasmas. The calculated results align well with the experimental findings within the margin of error. One notable observation from our study is the occurrence of an unusual phenomenon: as the HBr partial concentration increased, the Br⁺ ion flux initially increased until the ratio reached 0.5, after which it decreased. This behavior can be attributed to Br⁺ ions being predominantly produced through collisions between Br atoms and electrons. The dominant mechanisms for Br atom generation involve dissociations by Cl radicals, such as Br₂ + Cl → Br + BrCl. Consequently, there exists an optimal flow rate at which the Br⁺ ion flux is maximized.