On the importance of excited state species in low pressure capacitively coupled plasma argon discharges
| Autor: | De-Qi Wen, Janez Krek, Jon Tomas Gudmundsson, Emi Kawamura, Michael A. Lieberman, Peng Zhang, John P Verboncoeur |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Plasma Sources Science and Technology. |
| ISSN: | 1361-6595 0963-0252 |
| Popis: | In the past three decades, first principles-based fully kinetic Particle-in-Cell Monte Carlo collision (PIC/MCC) simulations have been proven to be an important tool for the understanding of the physics of low pressure capacitive discharges. However, there is a long-standing issue that the plasma density determined by PIC/MCC simulations shows quantitative deviations from experimental measurements, even in argon discharges, indicating that certain physics may be missing in previous modelling the low pressure rf driven capacitive discharges. In this work, we report that the energetic electron-induced secondary electron emission and excited state atoms play an important role in low pressure rf capacitive argon plasma discharges. The ion-induced secondary electrons are accelerated by the high sheath field to strike the opposite electrode and produce a considerable number of secondary electrons that produce additional ionizing impacts and further increase the plasma density. Importantly, the presence of excited state species even further enhances the plasma density via excited state neutral and resonant state photon-induced secondary electron emission on the electrode surface. The PIC/MCC simulation results show good agreement with the recent experimental measurements in the low pressure range (1-10Pa) that is commonly used in the etching semiconductor industry. At the highest pressure (20Pa) and driving voltage amplitudes 250 and 350V explored here, the plasma densities from PIC/MCC simulations considering excited state neutrals and resonant photon-induced secondary electron emission are quantitatively higher than the experiments, requiring further investigation on high pressure discharges. |
| Databáze: | OpenAIRE |
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