The particle trap and plasma parameter studies in an RF argon discharge

Abstract

Low pressure plasma discharges have been an important process in the manufacturing of microelectronics devices since the late seventies. Therefore, the knowledge and control of the physical and chemical phenomena in plasmas are important for reactor design and process development. In order to understand the process, it is necessary to be able to make accurate measurements of plasma parameters, such as charged particle density, electron temperature, and ion energy. There are three objectives in this research; the first objective is to develop a new automatic electrostatic probe system in order to make accurate measurements of plasma parameters such as plasma potential φ₀, electron temperature Tₑ, electron density nₑ, and electron energy distribution function (EEDF). The second objective is to investigate the forces acting on contaminant particle which can be generate during process. The final objective is to understand the physical nature of the plasma which is very sensitive to changes of processing variables such as rf power and pressure. It was discovered that both ion drag and electrostatic forces induce particle trapping. Additionally, over the range of processing variables explored, the mode of heating transited from ohmic to stochastic, resulting in a variation of the plasma parameters.