In micro- and nanotechnology, highly precise components with tall, narrow structures (high aspect ratios) made from semiconductor materials like silicon are important. A promising fabrication method is gas-phase metal-assisted chemical etching (MacEtch). In this plasma-free process, a thin metal layer defines the pattern on the silicon substrate. The etching step takes place in a chemical environment, where the reaction occurs only at the interface between the metal and silicon. The metal catalyst gradually sinks into the silicon, directing the etching deeper.
