Fabrication of Silicon-Oxide Thin Film by Using Ionized Physical Vapor Deposition and Application to Gate Insulators in Transparent Thin-Film Transistors

Abstract

Using an ionized physical vapor deposition (IPVD) apparatus, we formed a low-temperature silicon-oxide gate insulator (GI) for top-gate-type In-Ga-Zn oxide channel transparent thin-film transistors (IGZO-TTFTs) for the first time. IGZO-TTFTs with SiOx GIs (100 nm) showed a low gate leakage current of about 10(-12) A up to 30 V (gate voltage) comparable to all AlOx GI fabricated by atomic layer deposition (ALD). However, it had a high drain off-current (similar to 10(-8) A) with a low drain current, on-off ratio of similar to 10(-2) A due to the inductively coupled plasma (ICP) stream during the IPVD-GI process. In order to protect; an IGZO channel layer from the plasma effect., we deposited a shallow AlOx (10 nm) layer on the IGZO by using ALD. Using this double-layered GI, a high mobility transistor (30.95 cm(2)/sV) with a drain current on-off ratio of similar to 10(6) could be achieved.