In-situ large scale deposition of PZT films by RF magnetron sputtering

In the present study, high quality PZT films were deposited by RF magnetron sputtering onto 200mm thermally oxidized silicon substrates at substrate holder temperatures (T_h) between 550°C - 700°C using PbO-enriched single ceramic PZT targets. The high substrate temperatures used here allowed direct growth of the piezoelectric perovskite phase and rendered an additional post annealing step unnecessary. The PZT layers were grown on (111) oriented Pt bottom electrodes, which were covered by thin TiO₂ seed layers. Over the temperature range investigated here, there was a monotonic reduction in the Pb/(Zr+Ti) atomic ratio with increasing Th; the stoichiometry of the morphotropic phase boundary Pb/(Zr+Ti) ~ 1 and Zr/(Zr+Ti) ~ 0.53 was obtained at 700°C. However, the XRD patterns indicated that the films prepared at intermediate T_h = 600°C exhibited the minimum volume fraction of the spurious pyrochlore phase in addition to tetragonal and rhombohedral piezoelectric PZT structures. All PZT films contained mixed (110), (111) and (200) crystallographic orientations whose relative intensities were significantly influenced by T_h. The highest piezoelectric coefficients d_33,f = 120 pm/V and e_31,f = -12.6 C/m² were obtained for the films deposited at T_h = 600°C.