Ti/Cu bilayer electrodes for SiNx-passivated Hf-In-Zn-O thin film transistors: Device performance and contact resistance

In this study, we examine the possibility of using Ti/Cu bilayer as source/drain electrodes for SiNx-passivated Hf-In-Zn-O (HIZO) thin film transistors by comparing their electrical properties with devices that use Mo electrodes. The Mo devices operate in depletion mode with a higher field effect mobility, while the Ti/Cu devices exhibit an improved subthreshold swing and operate in enhancement mode. Transmission electron microscopy characterization reveals the formation of an amorphous TiOx layer at the Ti/HIZO interface, which is suggested to be responsible for the disparate device characteristics in terms of contact resistance and threshold delay. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3505151]