Oxygen Atom Neutral Beam Assisted Deposited Al2O3 and its Application to the Fabrication of Zinc Oxide Thin Film Transistor

Abstract

In the fabrication of zinc oxide thin film transistor(ZnO TFT), aluminum oxide(Al2O3) was deposited as gate insulator by using an oxygen atom neutral beam assisted deposition(NBAD) during e-beam evaporation. From the thickness of the Al2O3 layer evaporated with the oxygen NBAD process and the C-f measurement of metal-insulator-metal(MIM) capacitors fabricated with the NBAD Al2O3 layer, it was possible to conclude that the NBAD Al2O3 layer has a higher thickness and a higher dielectric constant at an acceleration beam energy of 300 eV as a result of the additional deposition of oxygen atoms during e-beam evaporation. The fabricated ZnO TFT with the NBAD Al2O3 gate insulator showed better electrical characteristics, such as a lower subthreshold swing and a higher on-off ratio, than those without any NBAD process.