Indium tin oxide thin films for metallization in microelectronic devices

The use of sputtered indium tin oxide (ITO) thin films as metal layers in silicon-based electronic circuits has been investigated. The ITO films were sputtered directly from In₂O₃/SnO₂ targets under inert ambient in an r.f. sputtering system. The films were characterized as functions of process parameters such as r.f. power, substrate temperature and post-deposition annealing treatments. The properties studied included sheet resistance, transparency, thickness uniformity, composition and structure, step coverage, and etchability. In addition, the suitability of these ITO films as interconnects in microelectronic devices was examined by fabricating MOSFET devices using fine line patterned ITO for the metallization.