Electrical, structural, and chemical properties of HfO(2) films formed by electron beam evaporation
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Date
2008-09-28
Authors
Cherkaoui, Karim
Monaghan, Scott
Negara, Muhammad A.
Modreanu, Mircea
Hurley, Paul K.
O'Connell, Dan
McDonnell, S.
Hughes, Gregory
Wright, S.
Barklie, R. C.
Journal Title
Journal ISSN
Volume Title
Publisher
AIP Publishing
Published Version
Abstract
High dielectric constant hafnium oxide films were formed by electron beam (e-beam) evaporation on HF last terminated silicon (100) wafers. We report on the influence of low energy argon plasma (similar to 70 eV) and oxygen flow rate on the electrical, chemical, and structural properties of metal-insulator-silicon structures incorporating these e-beam deposited HfO(2) films. The use of the film-densifying low energy argon plasma during the deposition results in an increase in the equivalent oxide thickness (EOT) values. We employ high resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS), and medium energy ion scattering experiments to investigate and understand the mechanisms leading to the EOT increase. We demonstrate very good agreement between the interfacial silicon oxide thicknesses derived independently from XPS and HRTEM measurements. We find that the e-beam evaporation technique enabled us to control the SiO(x) interfacial layer thickness down to similar to 6 angstrom. Very low leakage current density (< 10(-4) A/cm(2)) is measured at flatband voltage +1 V into accumulation for an estimated EOT of 10.9 +/- 0.1 angstrom. Based on a combined HRTEM and capacitance-voltage (CV) analysis, employing a quantum-mechanical CV fitting procedure, we determine the dielectric constant (k) of HfO(2) films, and associated interfacial SiO(x) layers, formed under various processing conditions. The k values are found to be 21.2 for HfO(2) and 6.3 for the thinnest (similar to 6 angstrom) SiO(x) interfacial layer. The cross-wafer variations in the physical and electrical properties of the HfO(2) films are presented.
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Keywords
Gate dielectrics , Hafnium oxide , Interface , Silicon , Defects , Deposition , Layer , Si , Transistors , Thickness , Electron beam deposition , Thin films , X-ray photoelectron spectroscopy , Dielectric thin films , High resolution transmission electron microscopy
Citation
Cherkaoui, K., Monaghan, S., Negara, M. A., Modreanu, M., Hurley, P. K., O’Connell, D., McDonnell, S., Hughes, G., Wright, S., Barklie, R. C., Bailey, P. and Noakes, T. C. Q. (2008) 'Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation', Journal of Applied Physics, 104(6), pp. 064113. doi: 10.1063/1.2978209
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Copyright
© 2008 American Institute of Physics, This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Cherkaoui, K., Monaghan, S., Negara, M. A., Modreanu, M., Hurley, P. K., O’Connell, D., McDonnell, S., Hughes, G., Wright, S., Barklie, R. C., Bailey, P. and Noakes, T. C. Q. (2008) 'Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation', Journal of Applied Physics, 104(6), pp. 064113 and may be found at http://aip.scitation.org/doi/abs/10.1063/1.2978209