High-Temperature Stable Amorphous Sn-Rich InSnGaO Thin Films Fabricated Via Atomic Layer Deposition for Next-Generation Dynamic Random-Access Memory Applications

Facile phase transitions and electrical degradation of amorphous oxide semiconductors due to a high thermal budget have significantly limited their dynamic random-access memory (DRAM) applications, which require high thermal stability at temperatures over 600 °C. In this paper, we report an amorphous In-Sn-Ga-O (ITGO) semiconductor fabricated via atomic layer deposition, which exhibits high-temperature (∼700 °C) phase stability with moderate electrical properties. The optimal Sn-rich ITGO composition (In/Sn/Ga = 25:58:17 at. %) represents a thermally stable amorphous phase with excellent Hall mobility (24.0 cm²/(V s)) above 600 °C. Various analytical and simulation methods reveal the role of Sn as an efficient amorphous stabilizer and enhancer of electron mobility in oxide semiconductors. A thin-film transistor with a 4.5 nm-thick ITGO channel demonstrates excellent field-effect mobility (7.7 cm²/(V s)) and reliability. Therefore, Sn-rich ITGO is a promising candidate for next-generation DRAM channels that require amorphous-phase stability at a high thermal budget.