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Title: Understanding the switching mechanism of interfacial phase change memory

Abstract

Phase Change Memory (PCM) is a top candidate for next generation data storage, but it typically suffers from high switching (RESET) current density (20–30 MA/cm 2). Interfacial Phase Change Memory (IPCM) is a type of PCM using multilayers of Sb 2Te 3/GeTe, with up to 100× lower reported RESET current compared to the standard Ge 2Sb 2Te 5-based PCM. Several hypotheses involving fundamentally new switching mechanisms have been proposed to explain the low switching current densities, but consensus is lacking. Here, we investigate IPCM switching by analyzing its thermal, electrical, and fabrication dependencies. First, we measure the effective thermal conductivity (~0.4 W m -1 K -1) and thermal boundary resistance (~3.4 m 2 K GW -1) of Sb 2Te 3/GeTe multilayers. Simulations show that IPCM thermal properties account only for an ~13% reduction of current vs standard PCM and cannot explain previously reported results. Interestingly, electrical measurements reveal that our IPCM RESET indeed occurs by a melt-quench process, similar to PCM. Finally, we find that high deposition temperature causes defects including surface roughness and voids within the multilayer films. Thus, the substantial RESET current reduction of IPCM appears to be caused by voids within the multilayers, which migrate to themore » bottom electrode interface by thermophoresis, reducing the effective contact area. These results shed light on the IPCM switching mechanism, indicating that an improved control of layer deposition is necessary to obtain reliable switching.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1];  [3]; ORCiD logo [4];  [5]; ORCiD logo [1]
  1. Stanford Univ., CA (United States). Dept. of Electrical Engineering
  2. Stanford Univ., CA (United States). Dept. of Electrical Engineering; Stanford Univ., CA (United States). Dept. of Mechanical Engineering
  3. Stanford Univ., CA (United States). Dept. of Mechanical Engineering
  4. Stanford Univ., CA (United States). Dept. of Electrical Engineering; Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
  5. Stanford Univ., CA (United States). Dept. of Mechanical Engineering; Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE; National Science Foundation (NSF)
OSTI Identifier:
1532494
Grant/Contract Number:  
AC02-76SF00515; ECCS-1542152; ECCS-1709200; EEC-1449548
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 125; Journal Issue: 18; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

Citation Formats

Okabe, Kye L., Sood, Aditya, Yalon, Eilam, Neumann, Christopher M., Asheghi, Mehdi, Pop, Eric, Goodson, Kenneth E., and Wong, H. -S. Philip. Understanding the switching mechanism of interfacial phase change memory. United States: N. p., 2019. Web. doi:10.1063/1.5093907.
Okabe, Kye L., Sood, Aditya, Yalon, Eilam, Neumann, Christopher M., Asheghi, Mehdi, Pop, Eric, Goodson, Kenneth E., & Wong, H. -S. Philip. Understanding the switching mechanism of interfacial phase change memory. United States. doi:10.1063/1.5093907.
Okabe, Kye L., Sood, Aditya, Yalon, Eilam, Neumann, Christopher M., Asheghi, Mehdi, Pop, Eric, Goodson, Kenneth E., and Wong, H. -S. Philip. Mon . "Understanding the switching mechanism of interfacial phase change memory". United States. doi:10.1063/1.5093907.
@article{osti_1532494,
title = {Understanding the switching mechanism of interfacial phase change memory},
author = {Okabe, Kye L. and Sood, Aditya and Yalon, Eilam and Neumann, Christopher M. and Asheghi, Mehdi and Pop, Eric and Goodson, Kenneth E. and Wong, H. -S. Philip},
abstractNote = {Phase Change Memory (PCM) is a top candidate for next generation data storage, but it typically suffers from high switching (RESET) current density (20–30 MA/cm2). Interfacial Phase Change Memory (IPCM) is a type of PCM using multilayers of Sb2Te3/GeTe, with up to 100× lower reported RESET current compared to the standard Ge2Sb2Te5-based PCM. Several hypotheses involving fundamentally new switching mechanisms have been proposed to explain the low switching current densities, but consensus is lacking. Here, we investigate IPCM switching by analyzing its thermal, electrical, and fabrication dependencies. First, we measure the effective thermal conductivity (~0.4 W m-1 K-1) and thermal boundary resistance (~3.4 m2 K GW-1) of Sb2Te3/GeTe multilayers. Simulations show that IPCM thermal properties account only for an ~13% reduction of current vs standard PCM and cannot explain previously reported results. Interestingly, electrical measurements reveal that our IPCM RESET indeed occurs by a melt-quench process, similar to PCM. Finally, we find that high deposition temperature causes defects including surface roughness and voids within the multilayer films. Thus, the substantial RESET current reduction of IPCM appears to be caused by voids within the multilayers, which migrate to the bottom electrode interface by thermophoresis, reducing the effective contact area. These results shed light on the IPCM switching mechanism, indicating that an improved control of layer deposition is necessary to obtain reliable switching.},
doi = {10.1063/1.5093907},
journal = {Journal of Applied Physics},
number = 18,
volume = 125,
place = {United States},
year = {2019},
month = {5}
}

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Works referenced in this record:

Low-Power Switching of Phase-Change Materials with Carbon Nanotube Electrodes
journal, March 2011


Self-Aligned Nanotube–Nanowire Phase Change Memory
journal, January 2013

  • Xiong, Feng; Bae, Myung-Ho; Dai, Yuan
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  • DOI: 10.1021/nl3038097