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

Abstract

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 SiOx ILD. The fabricated IGZO TFTs show a subthreshold swing (SS) of 94.16 mV/decade and a linear-region field-effect mobility (μFE) of 23.06 cm2/Vs. The channel-width-normalized source/drain series resistance (RSDW) 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.