Investigation of Pt/Ti bottom electrodes for Pb(Zr,Ti)O-3 films

Pt films, as bottom electrodes for PZT capacitors, were deposited on Ti/SiO2/Si substrates using DC magnetron sputtering under various deposition conditions. The effects of post-annealing on surface morphology, element diffusion. microstructure and structural phase of the Pt films were investigated. The structure and electrical properties of PZT films deposited on Pt/Ti/SiO2/Si electrodes were also studied. As the deposition temperature of the Pt film increases and the deposition rate decreases, the film becomes dense so that Ti out-diffusion and film deformation are suppressed. The out-diffused Ti faciliates the formation of nucleation sites for perovskite PZT films. However, excess Ti out-diffusion not only decreases the total capacitance of the PZT films due to formation of an interfacial layer having a low dielectric constant but also degrades the leakage current characteristics of the PZT films due to deformation of the Pt electrode.