A Direct n(+)-Formation Process by Magnetron Sputtering an Inter-Layer Dielectric for Self-Aligned Coplanar Indium Gallium Zinc Oxide Thin-Film Transistors

An inter-layer dielectric (ILD) deposition process to simultaneously form the conductive regions of self-aligned (SA) coplanar In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) is demonstrated. N(+)-IGZO regions and excellent ohmic contact can be obtained without additional steps by using a magnetron sputtering process to deposit a SiO(x) ILD. The fabricated IGZO TFTs show a subthreshold swing (SS) of 94.16 mV/decade and a linear-region field-effect mobility (μ(FE)) of 23.06 cm(2)/Vs. The channel-width-normalized source/drain series resistance (R(SD)W) extracted using the transmission line method (TLM) is approximately as low as 9.4 Ω·cm. The fabricated ring oscillator (RO) with a maximum oscillation frequency of 1.75 MHz also verifies the applicability of the TFTs.