Enhancing carrier mobility of IGZO TFT fabricated by non‐vacuum mist CVD with O3 assistance

Recently, we succeeded in demonstrating an oxide TFT consisting of a channel layer (IGZO) and gate insulator (AlOx) continuously fabricated by non-vacuum mist CVD. In this report, each thin film and the interfaces of the films have been improved with ozone (O3) assistance, as the initial oxide TFT had poor characteristics compared with those of the IGZO TFT fabricated by the conventional vacuum process. A superhydrophilic interface between AlOx and IGZO was obtained by removing the adhered organic matter from the film surface. The breakdown fields (EBD) and dielectric constant (κ) of the AlOx thin films were improved from 6 to 8 MV/cm and from 6 to 7, respectively, and the carrier concentration of the IGZO thin film decreased from 1019 to 1016 cm–3. The oxide TFT exhibited field effect mobility (μlin) of 8.7 cm2/(Vs), sub-threshold slope (S) of around 0.3 V/dec. and hysteresis (ΔVH) of around 0.5 V. These values were obtained by improving each thin film and the interfaces of the films with O3 assistance. This result is an important first step toward non-vacuum oxide TFT fabrication processes. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)