Ion beam etching system with residual gas analysis

• Subject Area: Condensed Matter Physics
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556138159

Plasma-assisted etching is a versatile technology for the subtractive micro- or nano-patterning of a wide range of material classes. The material is removed by a physical etching process using accelerated ions (usually argon), by chemical etching using plasma-activated reactive gases, or by a combination of these two processes. In reactive ion beam etching (RIBE), the ions are additionally bundled to a beam, resulting in a direction-dependent anisotropic ablation. The RIBE system applied for here is intended to establish RIBE as a powerful and very flexible microstructuring process for a variety of different material systems and sample geometries at the University of Konstanz. This requires a system configuration offering a high degree of flexibility. A central component hereby is the ion source, which must deliver a collimated ion beam with a stable beam current in order to enable homogeneous ablation also on larger surfaces. Due to the non-selective but directed etching during physical ablation with accelerated argon ions, the RIBE process is ideally suited for patterning mechanically hard and chemically inert materials. In addition, it is possible to ‘polish’ the sample surface homogeneously over a large area by applying the ion beam under a shallow angle. Such a controlled ablation of the surface, while maintaining a high surface quality, is interesting in particular for transmission electron microscopy. Initial experiments have also shown that RIBE can be used to transfer a 2.5D mask created by grayscale lithography to a silicon substrate. In this way, silicon waveguides can be structured in all three spatial directions. In order to increase the selectivity for the processing of silicon-based materials, the ion beam etching system should have an ion source that works both with fluorine-containing gases (CF4) as well as argon. In order to ensure the most homogeneous and gentle etching processes possible, the RIBE system should be equipped with a sample stage that allows for tilting, automatic rotation, and cooling. A mass spectrometer for residual gas analysis shall enable endpoint control and precise stopping of the etching process, in particular in multilayers.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Ionenstrahl-Ätzanlage mit Restgasanalyse
• Instrumentation Group: 5180 Elektronen- und Ionenstrahl-Quellen und -Bearbeitungsgeräte
• Applicant Institution: Universität Konstanz
• Leader: Professor Dr. Sebastian Gönnenwein