Development of multi-level PCRAM showing four-resistance-level

• Project/Area Number: 15K14104
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Physical properties of metals/Metal-base materials
• Research Institution: Tohoku University
• Principal Investigator: SUTOU YUJI 東北大学, 工学研究科, 准教授 (80375196)
• Co-Investigator(Renkei-kenkyūsha): ANDO Daisuke 東北大学, 大学院工学研究科, 助教 (50615820) ; KOIKE Junichi 東北大学, 未来科学技術共同研究センター, 教授 (10261588) ; SAITO Yuta 独立行政法人産業技術総合研究所, ナノエレクトロニクス研究部門, 研究員 (50738052)
• Research Collaborator: SHINDO Satoshi 東北大学, 大学院工学研究科
• Project Period (FY): 2015-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2015: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 相変化メモリ / 不揮発性メモリ / アモルファス / 結晶化 / 相変化

Outline of Final Research Achievements

Phase change random access memory called PCRAM has attracted much attention as next generation nonvolatile memory because of its simple operation principle and production cost. PCRAM is operated by way of Joule heating to induce phase change between high resistance reset amorphous state and low resistance set crystalline state of phase change material. In this study, we proposed multi-level PCRAM showing four-resistance-level which can store 2 bit data. We investigated the composition dependence of Cu-Ge-Te film showing two-step crystallization process. Based on the results, we found that 23.4Cu-28.8Ge-47.8Te(CuGT)/GeTe(GT) stack-layered memory cell can exhibits four-resistance-level, i.e., [amo.CuGT+amo.GT], [amo.CuGT*cry.GT], [cry1.CuGT+cry.GT] and [cry2.CuGT+cry.GT]. These results indicate that Cu-Ge-Te/GeTe layered structure is expected to be multi-level PCRAM.

Research Products

• [Int'l Joint Research] Hanyang University(韓国)
• [Journal Article] Investigation of an erasing method for synaptic behavior in a phase change device using Ge1Cu2Te3 (GCT) (2016)
  • Author(s): J.S. An, C.M. Choi, S. Shindo, Y. Sutou, H.S. Jeong, Y.H. Song
  • Journal Title: Electronics Letters Volume: 52 Issue: 18 Pages: 1514-1515
  • DOI: 10.1049/el.2016.2211
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Feasibility study of multi-level PCRAM with multiple phase change layers (2015)
  • Author(s): Y. Sutou, Y. Saito, S. Shindo, J. Koike, J.M. Lee, Y.H. Song
  • Journal Title: European Symposium on Phase Change and Ovonic Science proceedings Volume: 1 Pages: 133-134
  • Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Ge-Cu-Te phase change material for PCRAM application (2016)
  • Author(s): Y. Sutou, Y. Saito, S. Shindo, J. Koike
  • Organizer: PRiME2016
  • Place of Presentation: Honolulu, Hawai
  • Year and Date: 2016-10-02
  • Int'l Joint Research / Invited
• [Presentation] Feasibility study of multi-level PCRAM with multiple phase change layers (2015)
  • Author(s): Y. Sutou
  • Organizer: European Symposium on Phase Change and Ovonic Science E/PCOS 2015
  • Place of Presentation: Amsterdam, Netherlands
  • Year and Date: 2015-09-07
  • Int'l Joint Research