A study of contact resistance between phase change material and electrode for next generation PCRAM

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H04113
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• 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): KOIKE Junichi 東北大学, 未来科学技術共同研究センター, 教授 (10261588) ; ANDO Daisuke 東北大学, 大学院工学研究科, 助教 (50615820) ; KOBAYASHI Keisuke 高知工科大学, 総合研究所, 客員教授 (50372149) ; SAITO Yuta 高知工科大学, 総合研究所, 客員教授 (50372149)
• Research Collaborator: SONG Yun-Heub ; SHINDO Satoshi
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 相変化メモリ / 不揮発性メモリ / アモルファス / 結晶 / 接触抵抗

Outline of Final Research Achievements

With the scaling down of PCRAM cells, contact resistance between phase change material (PCM) and an electrode becomes a dominant factor in determining the memory cell resistance. In this study, we investigated the contact resistivity of PCM to a metal electrode. Then, we discussed the effect of the contact resistivity on the performance of the memory cell.
We found that an amorphous Cu2GeTe3 (CGT)/W contact shows schottky conduction, i.e., a CGT/W is dominated by interface conduction. Moreover, we found new PCM, Cr2Ge2Te6 (CrGT) with a high thermal stability in amorphous state. The CrGT showed inverse resistance change upon phase change (Ramo<Rcry). Although the resistivity change of the CrGT was only one order of magnitude, the contact resistivity change was found to reach two orders of magnitude upon phase change. I was also found that the CrGT memory cell achieves more than an 85% reduction in total operation energy compared with a conventional GST memory cell.

Free Research Field

材料工学