Fabrication and characterization of Zr-rich Zr-aluminate films for high-κ gate dielectric applications

Two kinds of Zr-rich Zr-aluminate films for high-κ gate dielectric applications with the nominal composition of (ZrO2)0.8(Al2O3)0.2 and (ZrO2)0.9(Al2O3)0.1, were deposited on n-type silicon wafer by pulsed laser deposition (PLD) technique at different deposition conditions. X-ray diffraction (XRD) reveals that the (ZrO2)0.8(Al2O3)0.2 film could remain amorphous after being rapid thermal annealed (RTA) at the temperature above 800 °C, while the other one displays some crystalline peaks at 700 °C. The energy gap calculated from optical transmittance spectrum of (ZrO2)0.8(Al2O3)0.2 film on quartz is about 6.0 eV. Sputtering depth profile of X-ray photoelectron spectroscopy and Auger electron spectroscopy indicate that a Zr–Si–O interfacial layer was formed at the near surface of the silicon substrate. The dielectric constant of the (ZrO2)0.8(Al2 O3)0.2 film has been determined to be 22.1 by measuring a Pt/(ZrO2)0.8(Al2 O3)0.2/Pt MIM structure. An EOT of 1.76 nm with a leakage current density of 51.5 mA/cm2 at 1 V gate voltage for the film deposited in N2 were obtained. Two different pre-treatments of Si substrates prior to depositions were also carried out and compared. The results indicate that a surface-nitrided Si substrate can lead to a lower leakage current density. The amorphous Zr-rich Zr-aluminate films fabricated by PLD have promising structure and dielectric properties required for a candidate material for high-κ gate dielectric applications.