Effects of e-beam deposited gate dielectric layers with atmospheric pressure plasma treatment for IGZO thin-film transistors

In this report, indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) performances were improved using atmospheric pressure plasma treatment on e-beam deposited silicon dioxide gate dielectric layers. The impact on the electrical properties of the IGZO-TFTs with different plasma powers at fixed N2 gas flow rate on the SiO2 dielectric surface has been investigated. The performances of the IGZO TFTs showed improvement at high power of 300 W and 400 W treatments. The amorphous IGZO films on SiO2/ITO glass achieved transmittance higher than 90% in the wavelength range of 350-1000 nm, and it could be further enhanced with increasing plasma treatment power. The reduced surface roughness in the SiO2 gate dielectric layer from increased plasma power would affect the performance of IGZO TFTs, especially by higher current on/off ratio, enhanced electron mobility, reduced sub-threshold swing voltage and interfacial trap charge density, and decreased threshold voltage. The amorphous IGZO TFTs with plasma treatment power at 400 W exhibited the field effect mobility, sub-threshold swing, on-current to off-current ratio, interfacial trap density and threshold voltage of 33.5 cm2/V s, 0.10 V/dec, 107, 1.2 × 1012 cm− 2 eV− 1 and 0.77 V, respectively. In addition, the high mobility of 33.5 cm2/V s was achieved using simple and cost-effective atmospheric pressure plasma treatment on e-beam deposited SiO2 gate dielectrics.