Preparation of PZT thin film by zirconium oxyacetate-based chemical solution deposition: Investigation for structure of bottom electrode and effect of excessive Pb

The PZT thin films of about 100 nm or less in thickness on the Pt/IrO ₂ and Pt/TiO_x bottom electrodes were prepared by the novel chemical solution deposition process using zirconium oxyacetate as starting material of Zr. In addition, the effects of the excessive Pb to the precursor solution were examined on the crystallinity and the P-V property. PZT thin films prepared from the precursor solutions lowered the temperature starting to make perovskite phase after annealing at 450°C and 550°C for Pt/IrO ₂ and Pt/TiO_x, respectively, which was lower than usual one. Among the bottom electrode structures tested, the Pt/TiO _x/SiO₂/Si structure with about 75 nm Pt in thickness was chosen from the viewpoint of the flatness. PZT thin films of 100 nm in thickness were deposited on the annealed Pt/TiO_x/SiC₂/Si optimally by using a novel precursor solution involving excessive Pb. Root-mean-square (RMS) roughness of PZT thin film increased from 2.59 nm to 6.67 nm with increasing excess Pb content from 0 to 15%. Remanent polarization (Pr) began to increase when the excess Pb exceeded 4%. On the other hand, coercive field (Ec) went through a minimum at 7% excess Pb before increasing much at 10%. Considering from these results, the Pb content optimal for the PZT thin film deposited on Pt/TiO_xSiO₂/Si was suggested to be 7% in excess of the stoichiometry.