High-Speed Etching of Indium-Tin-Oxide Thin Films Using an Inductively Coupled Plasma

The dry etching of indium-tin-oxide (ITO) films using a high-density inductively coupled rf plasma is described. Various etching characteristics are examined for an etching gas of CH4/H2 mixture. A very high etching rate of ITO films of over 200 nm/min was obtained at 100% CH4, while the high etching rate of ∼100 nm/min was achieved even at 100% H2 with the moderate dc self-bias voltage of 300 V. The etch selectivity of ITO to SiO2 and Si3N4 was over ∼10. The dependences of etching rate on substrate temperature and self-bias dc voltage suggest that the high-flux ion bombardment given by the inductive rf plasma enhances the etching of ITO films. On the other hand, the crystallinity of ITO has a nominal effect on the etching characteristics of ITO films.