Optimization of Reactive-Ion Etching (RIE) parameters to maximize the lateral etch rate of silicon using SF6/N2 gas mixture: An alternative to etching Si in MEMS with Au components

• Published in: Materials letters Vol. 285; p. 129058
• Main Authors: Kazar Mendes, M., Ghouila-Houri, C., Hammami, S., Arnoult, T., Pernod, P., Talbi, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.02.2021; Elsevier BV; Elsevier
• Subjects: Au thin films; Design optimization; DOE; Engineering Sciences; Etching; Flow velocity; Gas flow; Gas mixtures; Isotropic Si RIE; Materials; Materials science; MEMS; Micro and nanotechnologies; Microelectromechanical systems; Microelectronics; Microstructure; Parameters; Reactive ion etching; SF6/N2 plasma; Silicon; Structural damage; SF6/N2 plasma; Isotropic Si RIE; MEMS; DOE; Microstructure; Au thin films; Au Thin films
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2020.129058

•We develop a method to etch Si isotropically in MEMS with Au components.•N2 addition on the SF6 plasma protects Au thin films during the RIE process.•Doehlert DOE was applied to maximize Si lateral etch rate using SF6/N2 plasma. In this work, the effects of the N2 addition to the SF6 plasma used in the isotropic silicon etching of Micro-electromechanical systems (MEMS) with Au components are investigated. A four-variables Doehlert design was implemented for optimizing the etching parameters (power, pressure, gas flow rate, and N2/SF6 ratio) to maximize the lateral etch rate of Si using SF6/N2 gas mixture. The optimized etch condition founded for a lateral etch rate of 1.8 µm/min was: power = 143 W, chamber pressure = 86 mTorr, flow rate = 22 sccm, and N2/SF6 ratio = 0.1. Furthermore, it was demonstrated that the established etching process avoids the structure damage of Au components.