Development of HfO2-based ferroelectric tunneling junctions for artificial synapses

• Project/Area Number: 18H01484
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: SAWA Akihito 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, 研究員 (10357171)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥17,550,000 (Direct Cost: ¥13,500,000、Indirect Cost: ¥4,050,000); Fiscal Year 2020: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2019: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2018: ¥9,620,000 (Direct Cost: ¥7,400,000、Indirect Cost: ¥2,220,000)
• Keywords: 電子・電気材料 / 表面・界面物性 / トンネル接合

Outline of Final Research Achievements

In order to evaluate the potential of ferroelectric tunnel junctions (FTJs) for an artificial synapse, we investigated spike-timing-dependent plasticity (STDP) characteristics of BaTiO3-based FTJs. We demonstrated stable STDP characteristics in the BaTiO3-based FTJ, i.e., the variation in conductance change in STDP curve of the BaTiO3-based FTJ was much smaller than that of conventional resistive switching memories. We also developed a fabrication technique of polycrystalline ferroelectric HfO2 films with sharp and uniform interfaces over a large area on indium-tin oxide (ITO) layers and demonstrated resistive switching in FTJs with 2.4-nm-thick Zr-doped HfO2 barrier layers.

Academic Significance and Societal Importance of the Research Achievements

近年、ニューロモルフィックチップの精力的な開発が展開され、その構成要素である人工シナプスとして、酸化物抵抗変化メモリ(ReRAM)などの抵抗変化メモリを用いたアレイ回路の開発が進められている。本研究では、半導体プロセスと親和性の良いHfO2系強誘電体を用いた抵抗変メモリの一種であるFTJの開発や、FTJがReRAMよりも動作安定性の優れたSTDPシナプスとして動作すること実証した。この成果を発展させることで、FTJを人工シナプスとして用いた低消費電力のスパイキングニューラルネットワーク回路の開発が期待される。

Research Products

• [Journal Article] Spike-shape dependence of the spike-timing dependent synaptic plasticity in ferroelectric-tunnel-junction synapses (2019)
  • Author(s): Stoliar P.、Yamada H.、Toyosaki Y.、Sawa A.
  • Journal Title: Scientific Reports Volume: 9 Issue: 1 Pages: 17740-17740
  • DOI: 10.1038/s41598-019-54215-w
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Growth and ferroelectric properties of yttrium-doped hafnium oxide/indium-tin oxide polycrystalline heterostructures with sharp and uniform interfaces (2018)
  • Author(s): Yamada Hiroyuki、Toyosaki Yoshikiyo、Sawa Akihito
  • Journal Title: Journal of Applied Physics Volume: 124 Issue: 10 Pages: 105305-105305
  • DOI: 10.1063/1.5046866
  • Peer Reviewed
• [Presentation] BaTiO3-FTJの抵抗変化メモリ効果とシナプス応用 (2019)
  • Author(s): 澤彰仁，山田 浩之， Stoliar Pablo, 豊崎 喜精
  • Organizer: 第80回応用物理学会秋季学術講演会
  • Invited
• [Presentation] 酸化物界面物性と電子デバイス応用 (2019)
  • Author(s): 澤彰仁，山田 浩之
  • Organizer: 第80回応用物理学会秋季学術講演会
  • Invited
• [Presentation] Nonvolatile resistive switching memories based on ferroelectric tunnel junctions (2018)
  • Author(s): 澤 彰仁、豊崎 喜精、山田 浩之
  • Organizer: International Conference on Nanoelectronics Strategy
  • Int'l Joint Research
• [Presentation] Highly Stable Artificial STDP Synapse Based on Oxide FET (2018)
  • Author(s): Stoliar Pablo、Schulman Alejandro、鬼頭 愛、澤 彰仁、井上 公
  • Organizer: 5th International Workshop on Complex Oxides
  • Int'l Joint Research
• [Presentation] Effects of Interfaces and Electrode Materials on Ferroelectric Resistive Switching Characteristics (2018)
  • Author(s): 澤彰仁，山田 浩之，豊崎 喜精, Stoliar Pablo
  • Organizer: 18th IEEE Non‐Volatile Memory Technology Symposium
  • Int'l Joint Research / Invited