Specific Features of Matching of a Lower Electrode and an RF Bias Generator for Reactive Ion Etching of Bulk Substrates

• Published in: Technical physics 2021-12, Vol.66 (12), p.1294-1300
• Main Authors: Poletayev, S. D., Lyubimov, A. I.
• Format: Article
• Language: English
• Subjects: Argon; Bias; Chlorofluorocarbons; Classical and Continuum Physics; Electrodes; Etching; Hypotheses; Matching; Physics; Physics and Astronomy; Reactive ion etching; Substrates
• ISSN: 1063-7842; 1090-6525
• DOI: 10.1134/S1063784221040150

Theoretical and experimental results on reactive ion etching of bulk substrate in freon-14 with RF bias on the lower electrode are presented. A hypothesis in accordance with which a bulk substrate disturbs matching of the lower electrode and RF generator due to an additional reactive component in the impedance of the lower electrode is proposed. Reactive ion etching of substrates with different sizes in the CF 4 medium is numerically simulated. The simulated results show a significant increase in the reactive component of the RF power on the lower electrode when the diameter of the substrate is greater than 50% of the diameter of the lower electrode, which is in agreement with the proposed hypothesis. Distortion of matching of the lower electrode and RF generator is experimentally demonstrated for etching of bulk substrates. A specific holder is developed for bulk substrates. It is shown that such a substrate holder provides substantially better matching of the RF generator and lower electrode, especially, when argon is added to the plasma forming mixture at 0.3–0.9 L/h.