Lead Zirconate Titanate Thin Films Directly on Copper Electrodes for Embedded Passive Applications

摘要

We demonstrate that it is possible to process lead zirconate titanate (Pb(Zr{sub}0.52Ti{sub}0.48)O{sub}3) thin films directly on base metal copper foils. Films were prepared by chemical solution deposition, pre-annealed to pyrolyze organic constituents, and annealed at 650°C for 15 minutes. We explore the impact of the oxygen partial pressure during processing, and demonstrate that high quality films and interfaces can be achieved through control of the pO{sub}2 within a narrow window predicted by thermodynamic stability considerations. Resultant films have good electrical properties with saturation polarization values around 55 μC/cm{sup}2, and switching polarization (～2P{sub}r) around 40 μC/cm{sup}2. Zero bias dielectric constants are around 1100. The demonstration opens up the possibility of the use of low cost, high conductivity copper electrodes for a range of Pb-based perovskite materials, including PZT films in embedded printed circuit board applications for capacitors. The other broad implications include embedded printed circuit board applications for varactors, and sensors; multilayer PZT piezoelectric stacks; and multilayer lead magnesium niobate-lead titanate-based dielectric and electrostrictive devices. We also point out that the capacitors upon repeated switching do not fatigue like those with Pt noble metal electrodes, but instead appear to be fatigue resistant like capacitors with oxide electrodes. This has important implications for ferroelectric nonvolatile memories.