Scanning Transmission Electron Microscopy Investigations of Interfacial Layers in HfO₂ Gate Stacks

Journal Article · Sun Jan 01 04:00:00 EST 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2214187· OSTI ID:1003220

Agustin, Melody P ^[1]; Bersuker, Gennadi ^[2]; Foran, Brendan ^[3]; Boatner, Lynn A ^[4]; Stemmer, Susanne ^[1]

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1. University of California, Santa Barbara
2. Sematech, Austin, TX
3. ATDF Inc., Austin, TX
4. ORNL

Electron energy-loss spectroscopy combined with high-angle annular dark-field (HAADF) imaging in scanning transmission electron microscopy was used to investigate the chemistry of interfacial layers in HfO{sub 2} gate stacks capped with polycrystalline Si gate electrodes. To interpret the energy-loss near-edge fine structure (ELNES) obtained from the interfacial layers, reference spectra were obtained from single crystal hafnium silicate (HfSiO{sub 4}), monoclinic HfO{sub 2} powder, and amorphous SiO{sub 2}. No bulk-like silicate bonding could be detected in the ELNES of Si L{sub 2,3} and O K edges recorded from layers at the Si substrate interface. Compared to bulk SiO{sub 2}, the interfacial ELNES showed additional features that were caused by overlap of signals from Si, HfO{sub 2}, and SiO{sub 2}, despite a relatively small electron probe size of -3 {angstrom}. HAADF showed that interfacial roughness caused the projected thickness of nominally pure SiO{sub 2} (within the detection limit of the method) to be as small as -5 {angstrom} in many locations.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003220
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 2 Vol. 100; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BONDING
CHEMISTRY
DIELECTRIC MATERIALS
ELECTRODES
ELECTRON MICROSCOPY
ELECTRON PROBES
ELECTRONS
ENERGY-LOSS SPECTROSCOPY
FINE STRUCTURE
HAFNIUM COMPOUNDS
HAFNIUM SILICATES
INTERFACES
LAYERS
MONOCRYSTALS
SILICATES
SILICON
SPECTRA
STACKS
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY