Interfacial and microstructural properties of zirconium oxide thin films prepared directly on silicon

Zirconium oxide thin films were deposited directly on Si by ultra high vacuum electron beam evaporation (UHV-EBE) and rapid thermal annealed (RTA) in O2 ambient at different temperatures ranging from 300 to 800 °C. X-ray photoelectron spectroscopy (XPS) revealed zirconium is in the fully oxidized state of Zr4+. X-ray diffraction (XRD) results showed that as-deposited thin films were amorphous. When the annealing temperature increased higher than 700 °C, the films began to crystallize. The surface topology was studied with atomic force microscopy (AFM) and the surface of the 700 °C-annealed sample was more rougher than that of the 600 °C-annealed sample, due to its potentially faceted interfaces. And the typical RMS roughness ranged from 0.546 to 0.666 nm across an area of 50 μm×50 μm. Sharp interfaces between ZrO2 and Si were obtained both by spreading resistance profile (SRP) and cross-sectional transmission electron microscope (XTEM). The interfacial oxide (∼1 nm) was not detected until annealing temperature amounting to 700 °C and the exact compositions were not known yet.