Journal article

Microstructure of PZT sol-gel films on Pt substrates with different adhesion layers

The influence of Ta, Ti and TiO2 adhesion layers with Pt bottom electrodes and the deposition temperature of the metallization on the nucleation and growth of sol-gel derived Pb(Zr0.53Ti0.47)O-3 thin films is reported. Several different PZT annealing profiles were simultaneously investigated to determine the role of PZT annealing on resultant PZT film microstructures for a given metallization. The adhesion layer was found to primarily influence PZT grain size. Largest grain sizes were observed for substrate structures with TiO2 adhesion layers. Slower heating rates resulted in rosette type structures and a large volume of residual pyrochlore, particularly in the case of TiO2 adhesion layers, while yielding only a grain size increase on Ti and Ta bonded substrates. These results were correlated to the stability of the adhesion layers in terms of diffusion through Pt and thus changes in the chemistry and structure of the film/Pt interface where the perovskite nucleation was observed to occur. The Pt metallizations were found to be more strongly (111) textured on the purely metallic adhesion layers and independent of the adhesion layer deposition temperature. PZT texture was found to be influenced by adhesion layer deposition temperature and PZT annealing profile. The perovskite texture was altered through annealing conditions only on TiO2 bonded substrates. The above results suggested a reduction of the number of perovskite nucleation sites on metallizations with TiO2 adhesion layer. This result is in agreement with Rutherford backscattering evidence from previous investigations.

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