Stable PZT sol for preparing reproducible high-permittivity perovskite-based thin films

Results are reported on the development of high-K dielectric material using sol-gel chemistry. High permittivity thin film capacitor have been developed based on lead-zirconate-titanate (PbZr _x Ti_1−x O₃, PZT) ferroelectric ceramic layers deposited on to 6″ platinized silicon wafer using the spin-coating technique. Selecting a diol-based solvent as diluting medium, a PZT solution with remarkable shelf life up to 1 year has been prepared. To synthesize such a reproducible and time-stable solution, a ripening step before dilution has been introduced. The deposition process has been also optimized to reduce the required number of coatings and to avoid intermediate high-temperature annealing. By carefully controlling environmental parameters, the as-developed PZT solution leads to reproducible high-performance thin film capacitor, enabling an industrial use. Thus, 200-nm thick PZT layers with permittivity as high as 900, capacitance as high as 40 nF/mm2 and breakdown voltage up to 30 V have been obtained.