Structure and dielectric properties of ultra-thin ZrO2 films for high-k gate dielectric application prepared by pulsed laser deposition

ZrO2 thin films have been prepared on Pt-coated silicon substrates and directly on n-Si(100) substrates by the pulsed laser deposition (PLD) technique using a ZrO2 ceramic target under different deposition conditions. X-ray diffraction showed that the films prepared at 400 C in 20 Pa oxygen ambient remained amorphous. Differential thermal analysis was carried out to study the crystallization behavior of ZrO2. The dielectric constant of ZrO2 was determined to be around 24 by measuring a Pt/ZrO2/Pt capacitor structure. Sputtering depth profile X-ray photoelectron spectroscopy was used to investigate the interfacial characteristics of ZrO2/n-Si stacks. A Zr silicate interfacial layer was formed between the ZrO2 layer and the silicon substrate. The equivalent oxide thickness (EOT) and leakage current densities of the films with 6.6 nm physical thickness post-annealed in O2 and N2 ambient were investigated. An EOT of 1.65 nm with a leakage current of 36.2 mA/cm2 at 1 V gate voltage for the film post-annealed in N2 has been obtained. ZrO2 thin films prepared by PLD have acceptable structure and dielectric properties required by a candidate material of high-k gate dielectrics. (orig.)