Interfacial stability between zirconium oxide thin films and silicon

Abstract

We studied the interfacial properties of ZrO 2 thin films deposited by ultra-high vacuum electron beam evaporation (UHV-EBE). Some samples were annealed in O 2 ambient by rapid thermal annealing (RTA) at different temperatures ranging from 300 to 700 °C. X-ray photoelectron spectroscopy (XPS) of all films, whether annealed or not, revealed that the binding energies of Zr3d 5/2 and Zr3d 3/2 are 183.5 and 185.7 eV, respectively, which are the typical peak values of Zr 4+. X-ray diffraction (XRD) results showed that the as-deposited film was amorphous, and it remained stable up to the annealing temperature of 600 °C. But when the temperature increased further attaining 700 °C, it began to crystallize. All the surfaces of the thin films were smooth and uniform. The typical RMS roughness ranged from 0.546 to 0.666 nm across an area of 50×50 μm. Steep and clear interfaces between zirconium oxide thin film and Si substrate were obtained both by spreading resistance profile (SRP) and cross-sectional transmission electron microscopy (XTEM). High quality of the interface without interfacial oxide was achieved when the annealing temperatures were kept under 600 °C, but when the temperature was raised to 700 °C, ∼1-nm thick oxide product was detected by XTEM. The component of the oxide product is not exactly known yet, but may be SiO x or ZrSi x O y .