The Mechanism of Ruthenium Oxide Catalyzed Electroless Etching of Silicon in Oxidizing HF Solution

While metal-assisted chemical etching (MACE) or metal-catalyzed electroless etching of silicon in oxidizing HF solutions typically employs noble metals as catalysts, this work investigates oxide-catalyzed chemical etching (OACE) using RuO2 to induce localized silicon etching in aqueous H2O2-HF solutions. RuO2 particles confine the reaction to localized sites. The formation of Ru2O3 during etching suggests that RuO2 injects holes into silicon and is simultaneously reduced to Ru2O3. The oxidized s