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P: Fachverband Plasmaphysik

P 21: Low Pressure Plasmas and their Application II

P 21.5: Vortrag

Donnerstag, 29. Februar 2024, 15:15–15:30, ELP 6: HS 3

Investigation of geometric asymmetric electronegative capacitively coupled radio frequency discharges using a hybrid PIC/MCC simulation — •Katharina Noesges, Maximilian Klich, Sebastian Wilczek, and Thomas Mussenbrock — Ruhr University Bochum, Germany

Capacitively coupled radio frequency (CCRF) discharges are pivotal in numerous etching processes in the semiconductor industry. Operating at low pressures in the range of a few Pascals and requiring voltages of about hundreds of volts, these discharges facilitate anisotropic ion bombardment essential for precision etching. Carbon tetrafluoride (CF₄) discharges are significant in this context. These discharges are investigated using a one-dimensional hybrid particle-in-Cell/Monte Carlo collisions (PIC/MCC) simulation in the low-pressure regime (p = 6.67 Pa), assuming a spherical geometry. This approach considers the electrons kinetically and simultaneously utilizes the drift-diffusion approximation to solve a continuity equation; one each for the ion species. This work examines the influence of varying electrode gap sizes and applied voltages, demonstrating that the electronegativity strongly affects the electron dynamics. Because of the geometric asymmetry, a strong electric field reversal during the sheath collapsing phase accelerates many electrons toward the powered electrode. A spatially and temporally resolved analysis of the high-energy electron density reveals a sharp beam structure formed by electrons near the electrode. This beam structure is an accumulation of electrons accelerated by the expanding boundary sheath towards the grounded electrode.

Keywords: CCP; Low pressure; Geometric asymmetric; Electronegative; hybrid PIC/MCC