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

Ryu, Seong-Hwan; Kim, Hye-Mi; Lee, Kwang-Hee; Sung, Ha-Jun; Yang, Jee-Eun; Kim, Sangwook; Park, Jin-Seong · Nano Lett · 2024

basic_science · Level V

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Abstract

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 cm<sup>2</sup>/(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 cm<sup>2</sup>/(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.