Controlling crystallinity and crystal orientation of PbTiO₃ and Pb(Zr, Ti)O₃ thin films by introducing different seed layers

The introduction of various seed layers produced thin films with different properties on the same substrate. PbTiO₃ (PT) and Pb (Zr_0.52Ti_0.48)O₃ (PZT) thin films with different crystallinities, crystal orientations and phases were successively fabricated on Nb doped SrTiO₃ (Nb-ST) and Pt/Ti/SiO₂/Si (Pt/Si) substrates, respectively, by introducing the SiO₂ and TiO₂ seed layers using a chemical solution deposition process. The optimum processing conditions for each combination of film, substrate and seed layers were examined from the viewpoint of the compatibility of the target film formation and the patterning process for realizing different cells on the same substrate. The c-axis oriented epitaxial PT film was formed on the Nb-ST substrate. By introducing TiO₂ and SiO₂ thin layers onto the Nb-ST substrate, the polycrystalline PT and amorphous film with PT composition were obtained, respectively. The (111) oriented PZT film, and the pyrochlore phase and PZT (110) were formed on Pt/Si without and with the SiO₂ seed layer, respectively. Combining the introduction of the seed layers and the photolithography technique, we succeeded in fabricating the thin films with different cells having various electrical properties on the same substrates. In the Pt/PZT/(with and without seed layer)/Pt/Si system, 200 μm^φ cells with ferroelectricity or dielectric properties were obtained on the same substrate.