Indium Tin Oxide Dry Etching Using HBr Gas for Thin‐Film Transistor Liquid Crystal Displays

The dry etching technique for indium tin oxide (ITO) films has been investigated using gas with a conventional parallel‐plate‐type reactive ion etching apparatus in order to fabricate ITO fine patterns for thin‐film transistor addressed liquid crystal displays (TFT‐LCDs). Etching rates of amorphous ITO and poly‐ITO were almost the same, unlike the case with ITO wet etching. This demonstrates that the ITO etching rate using gas is independent of the film characteristics. A scanning electron microscopy study of etched ITO films showed that the reaction products were not deposited on the sample surface, although the resist surface was roughened. Al films, which are the underlayers of ITO films for TFT‐LCDs, were not etched by gas only. Therefore, high ITO/Al selectivity can be obtained by gas.