Deap Reactive Ion Etching System for Silicon

• Subject Area: Systems Engineering
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 575390090

For research in the field of silicon-based MEMS (microelectromechanical systems) a deep reactive ion etching (DRIE) system is required that makes a cyclic etching process also known as BOSCH-process available. It is used for highly precise MEMS on silicon-on-insulator wafers wit diameters of 100 mm and 200 mm. All other required processes are already available in the cleanroom. The DRIE system should be equipped with a powerful ICP source and bias generators as well as fast mass flow controllers . Notching should be safely suppressed. The integration of an optical emission spectroscopy is required for an individual tuning of single etching cycles. It can either prevent silicon grass or allows its reproducible fabrication for IR antireflective coatings. The software should be able to use this information for process control. In the future, research on ecofriendly etching processes is planned. Therefore, a cooperation with the Chair for applied electrodynamics and plasma science at RUB is established for using so-called waveform tailoring for capacitive bias control for controlling the electron energy density. It allows to control the generation of relevant ions and radicals. New gases with less global warming potential (>22,000 for sulfur hexafluoride) will be investigated. Therefore, the system will be equipped with additional gas lines including those for bubbling liquid precursors such as hydrofluoric acid or other plasma-decomposable substances. This DRIE system will improve the research options at RUB significantly. The available DRIE (outside our cleanroom) is not suitable for any further extension and shows less reliability, but it will stay available for routine etching while the new system will add a wide portfolio of process options. Additional process gases or alternative RF generators for waveform tailoring will be subject of future research proposals. The DRIE system will now be located at our cleanroom, so it will be easier to use it also for teaching.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Plasma-Anlage zur zyklischen anisotropen Ätzung von Silicium
• Instrumentation Group: 0920 Atom- und Molekularstrahl-Apparaturen
• Applicant Institution: Ruhr-Universität Bochum
• Leader: Professor Dr.-Ing. Martin Hoffmann