2020 Fiscal Year Final Research Report

Development of d-electron based phase change chalcogenide for next generation non-volatile memory

Research Project

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Project/Area Number	18H02053
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
Research Institution	Tohoku University
Principal Investigator	Sutou Yuji 東北大学, 工学研究科, 教授 (80375196)
Co-Investigator(Kenkyū-buntansha)	齊藤雄太国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (50738052)
Project Period (FY)	2018-04-01 – 2021-03-31
Keywords	相変化メモリ / 不揮発性メモリ / アモルファス / 結晶化 / 結晶多形転移
Outline of Final Research Achievements	In this study, we focused on next-generation memory: phase-change memory which relies on the change in physical properties due to amorphous/crystalline phase change of phase-change material (PCM). We tried to develop new PCMs which can enhance phase-change memory performance. In transition-metal containing PCMs which enable lower energy-, faster speed-operation and higher heat resistance than conventional PCMs, transition-metal elements were found to form nano-clusters in the amorphous phase. The volume fraction of nano-clusters decreased with phase-change, which induces the drastic change in electrical properties. It was also found that the addition of nitrogen can suppress the formation of nano-clusters and control the electrical characteristics. Furthermore, we found a crystalline polymorphic PCM which does not require amorphization. The crystalline polymorphic phase-change material can realize phase-change memory showing ultralow energy- and ultrafast speed-operation.
Free Research Field	材料相変態
Academic Significance and Societal Importance of the Research Achievements	Society5.0に向け、膨大なデータを保管する不揮発性メモリの高性能化が強く求められている。現在主流の不揮発性メモリはその動作原理故に、その性能向上は限界に達しつつある。それ故、新メモリが世界中で研究開発されているが、中でも相変化メモリは、材料の相変化に伴う抵抗変化を利用してデータ記録する単純な動作原理を持つ。本研究では相変化メモリの革新に向け、従来性能を凌駕する新材料を創成し、その相変化挙動の解明に取り組んだ。相変化材料中の遷移金属元素の重要な役割を明らかにすると共に、省エネ、高速動作かつ高耐熱性を可能とする相変化メモリを実現する事に成功し、学術的にも工業的にも意義の高い成果を得た。