Crystallization in HfO 2 gate insulators with in situ annealing studied by valence-band photoemission and x-ray absorption spectroscopy

S. Toyoda, J. Okabayashi, H. Kumigashira, M. Oshima, K. Yamashita, M. Niwa, K. Usuda, G. L. Liu

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

We have investigated the valence-band and conduction-band electronic structures of HfO2 gate insulators on Si substrates and their dependence on the annealing temperature in ultrahigh vacuum and the Hf-metal predeposition at the interface by photoemission spectroscopy and x-ray absorption spectroscopy. In the case with the Hf-metal predeposition before the HfO2 deposition, the valence-band spectra were split into double-peak structures and the line shapes of O K -edge x-ray absorption spectra became sharp due to the annealing at 800 and 900 °C. On the other hand, without the Hf-metal predeposition, annealing-temperature dependence in these spectra was not observed. Cross-sectional transmission electron microscopy images reveal that the changes in both valence-band and O K -edge absorption spectra are related to the crystallization of the HfO2 layer, although it is difficult to distinguish the crystallization in Hf 4f core-level spectra. It suggests that the valence-band photoemission and x-ray absorption spectra can be utilized to investigate the crystallization features in ultrathin gate insulators.

Original languageEnglish
Article number104507
JournalJournal of Applied Physics
Volume97
Issue number10
DOIs
Publication statusPublished - 2005 May 15
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Crystallization in HfO <sub>2</sub> gate insulators with in situ annealing studied by valence-band photoemission and x-ray absorption spectroscopy'. Together they form a unique fingerprint.

Cite this