Effects of H2 sintering and Pt upper electrode on metallic Bi content in Sr0.9Bi2.1Ta2O9 thin films for ferroelectric memories prepared by sol-gel method

Ichiro Koiwa, Takao Kanehara, Hiroyo Kato, Sachiko Ono, Akira Sakakibara, Tetsuya Osaka, Katsuhiko Asami

Research output: Contribution to journalArticle

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Abstract

The effects of Pt electrode and H2 sintering on the metallic Bi content of Sr0.9Bi2.1Ta2O9 (SBT) thin films for ferroelectric memories were studied using X-ray photoelectron spectroscopy (XPS). Oxidic Bi in SBT films is reduced to metallic Bi by H2 sintering. The degree of reduction depends on the structure of the SBT film. The SBT film with a fluorite structure is more difficult to reduce than that with a Bi-layered structure. Pt upper electrode formation also leads to an increase of metallic Bi content. Both H2 sintering and the Pt upper electrode work synergistically. In the combination of the pure Pt upper electrode and H2 sintering, over 80% of Bi on the SBT film surface was metallic. Pt films of 5 nm thickness on the SBT film recrystallized during the heat treatment and were broken up into particles. Pt electrode coverage was about 20% after the 2nd annealing at 800°C for 30 min in O2 atmosphere. Electrical properties were significantly affected by the presence of metallic Bi; in particular, SBT films with higher metallic Bi content showed higher leakage current density. The metallic Bi content must therefore be suppressed to obtain SBT films with low leakage current density.

Original languageEnglish
Pages (from-to)5192-5197
Number of pages6
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume37
Issue number9 PART B
Publication statusPublished - 1998 Sep

Fingerprint

Sol-gel process
Ferroelectric materials
sintering
Sintering
gels
Data storage equipment
Thin films
Electrodes
electrodes
thin films
Leakage currents
leakage
Current density
current density
Fluorspar
fluorite
Electric properties
heat treatment
X ray photoelectron spectroscopy
electrical properties

Keywords

  • H sintering effect
  • Metallic Bi content
  • Pt upper electrode formation effect
  • Sol-gel method and ferroelectric memories
  • SrBiTaO thin film
  • X-ray photoelectron spectrometry (XPS)

ASJC Scopus subject areas

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

Cite this

Effects of H2 sintering and Pt upper electrode on metallic Bi content in Sr0.9Bi2.1Ta2O9 thin films for ferroelectric memories prepared by sol-gel method. / Koiwa, Ichiro; Kanehara, Takao; Kato, Hiroyo; Ono, Sachiko; Sakakibara, Akira; Osaka, Tetsuya; Asami, Katsuhiko.

In: Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, Vol. 37, No. 9 PART B, 09.1998, p. 5192-5197.

Research output: Contribution to journalArticle

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abstract = "The effects of Pt electrode and H2 sintering on the metallic Bi content of Sr0.9Bi2.1Ta2O9 (SBT) thin films for ferroelectric memories were studied using X-ray photoelectron spectroscopy (XPS). Oxidic Bi in SBT films is reduced to metallic Bi by H2 sintering. The degree of reduction depends on the structure of the SBT film. The SBT film with a fluorite structure is more difficult to reduce than that with a Bi-layered structure. Pt upper electrode formation also leads to an increase of metallic Bi content. Both H2 sintering and the Pt upper electrode work synergistically. In the combination of the pure Pt upper electrode and H2 sintering, over 80{\%} of Bi on the SBT film surface was metallic. Pt films of 5 nm thickness on the SBT film recrystallized during the heat treatment and were broken up into particles. Pt electrode coverage was about 20{\%} after the 2nd annealing at 800°C for 30 min in O2 atmosphere. Electrical properties were significantly affected by the presence of metallic Bi; in particular, SBT films with higher metallic Bi content showed higher leakage current density. The metallic Bi content must therefore be suppressed to obtain SBT films with low leakage current density.",
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