Low Temperature Fabrication of an Amorphous InGaZnO Thin-Film Transistor With a sol-gel SiO2Gate Dielectric

Abstract

In this study, low temperature fabrication of an amorphous InGaZnO thin-film transistor (a-IGZO TFT) was demonstrated. The maximum process temperature was 200 °C. The gate dielectric was a sol-gel SiO2 film while the channel layer was a sputtered a-IGZO semiconductor. The optimal sol-gel film for gate dielectric application was obtained by considering effects of surfactant, solvent, plasma treatment, and curing process on the film characteristics. The reasons for leakage current variations of the sol-gel films prepared with different conditions were examined by a scanning electron microscope and Fourier-transform infrared analysis. The leakage current mechanism of the optimal sol-gel SiO2 film was found to be dominated by Ohmic conduction. The characteristics of a-IGZO layers deposited with oxygen flow rates of 0–3 SCCM were investigated. By integrating the optimal sol-gel SiO2 dielectric and the sputtered a-IGZO layer, we successfully fabricated the TFT with a field effect mobility of 6.4 cm2/Vs. The interface trap density between the sol-gel SiO2 and the a-IGZO layer was found to be 9.2 × 1011 cm−2 eV−1.