On the Mechanism of ITO Etching in Halogen Acids: The Influence of Oxidizing Agents

The etching process of polycrystalline tin‐doped indium oxide (ITO) films in solutions is investigated by kinetic and electrochemical experiments and the patterning characteristics are examined by scanning electron microscopy. The influence of oxidizing agents on the etching behavior is studied. A model is proposed in which ITO is first attacked by undissociated molecules, forming a surface intermediate which is mobile on the surface. This intermediate can react with molecules or with the oxidizing agent. The competition between these two reactions determines the kinetics and the patterning characteristics of the dissolution process. A kinetic rate law is derived that predicts the etch rate in solutions. A good agreement between experimental and calculated values is obtained in a wide range of and concentrations.