Electrical characterization of metal-oxide-semiconductor memory devices with high-density self-assembled tungsten nanodots

Yan Li Pei, Takafumi Fukushima, Tetsu Tanaka, Mitsumasa Koyanagi

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Tungsten nanodots (W-NDs) with an ultrahigh density of 1 × 10 13/cm2 and a small size of around of 1.5-2 nm were successfully formed by self-assembled nanodot deposition (SAND). A metal-oxide-semiconductor (MOS) memory device was also fabricated with a W-ND layer placed between tunneling SiO2 and block SiO2. Using this device, the effects of annealing on the capacitance characteristics were investigated in detail. After 900 °C post deposition annealing (PDA), an extremely large memory window of about 9.2V was obtained, indicating that the device is a strong contender for future nonvolatile memory (NVM) applications. The program/erase speed and retention characteristics were also evaluated. The oxidation of tungsten by oxygen from the cosputtered silicon oxide was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. It is considered to degrade the retention characteristics of MOS memory devices.

Original languageEnglish
Pages (from-to)2680-2683
Number of pages4
JournalJapanese journal of applied physics
Volume47
Issue number4 PART 2
DOIs
Publication statusPublished - 2008 Apr 25

Keywords

  • Flash memory
  • Memory window
  • Retention
  • SAND
  • Tungsten nanodot

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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