OREGON STATE UNIVERSITY

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Atomic layer deposition of thin hafnium oxide films using a carbon free precursor

TitleAtomic layer deposition of thin hafnium oxide films using a carbon free precursor
Publication TypeJournal Article
Year of Publication2003
AuthorsConley, J. F., Y. Ono, D. J. Tweet, W. Zhuang, and R. Solanki
JournalJournal of Applied Physics
Volume93
Issue1
Pagination712-718
Date Published01/2003
ISSN00218979
Abstract

Thin HfO&#8322; films have been deposited on silicon via atomic layer deposition using anhydrous hafnium nitrate [Hf(NO&#8323;)&#8324;]. Properties of these films have been investigated using x-ray diffraction, x-ray reflectivity, spectroscopic ellipsometry, atomic force microscopy, x-ray photoelectron spectroscopy, and capacitance versus voltage measurements. Smooth and uniform initiation of film growth has been detected on H-terminated silicon surfaces. As-deposited films were amorphous, oxygen rich, and contained residual NO&#8323; and NO&#8322; moieties from the nitrate precursor. Residual nitrates were desorbed by anneals >400 °C, however, the films remained oxygen rich. Crystallization of thin films (<10 nm) occurred at roughly 700 °C. For films less than ∼10 nm thick, the effective dielectric constant of the film and any interfacial layer (neglecting quantum effects) was found to be in the range of k∼10−11. From a plot of electrical thickness versus optical thickness, the dielectric constant of the HfO&#8322; layer was estimated to be k<sub>HfO&#8322;</sub>-12-14. Leakage current was lower than that of SiO&#8322; films of comparable equivalent thickness. The lower than expected dielectric constant of the film stack is due in part to the presence of an interfacial layer (likely HfSiO&#8339;). Excess oxygen in the films may also play a role in the reduced dielectric constant of the HfO&#8322; layer.

DOI10.1063/1.1528306
Short TitleJ. Appl. Phys.