SELECTIVE REACTIVE ION ETCHING OF INDIUM-TIN OXIDE IN A HYDROCARBON-GAS MIXTURE

A new method for the reactive ion etching of a transparent conducting indium-tin oxide (ITO) film has been investigated. With a gas mixture consisting of acetone, argon, and oxygen, high etch rate selectivities of ITO to a number of underlying materials were achieved. A useful variation on the etch process employs hydrogen chloride in a first etch step followed by the acetone-based etch. Acetone is a source of reactive organic radicals in the plasma discharge that etch ITO films by forming volatile organometallic compounds. Selective chemical vapor deposition of carbon films on surfaces that do not etch can occur using this chemistry, but with sufficient oxygen in the plasma this is eliminated. An analysis of the plasma etch chemistry based on plasma emission spectroscopy is also presented.