Sputter deposition of YSZ epitaxial buffer layer at wafer level for piezoelectric MEMS utilizing PZT-based monocrystalline thin film

Yttria-stabilized zirconia (YSZ) for the initial buffer layer of lead zirconate titanate (PZT) was epitaxially deposited on a 4 inch Si wafer by radio-frequency magnetron sputtering, which was potentially applicable to mass-production. To avoid excessive oxidation of a Si surface, a seeding later was formed on Si by repeating the sputter-deposition and thermal oxidation of metallic Zr and Y. On the seed layer, YSZ was deposited up to 100 nm in thickness by reactive sputtering at 800. Cube-on-cube epitaxial growth and excellent crystallinity were confirmed by X-ray diffraction (XRD). On the buffer layer including YSZ at the bottom (YSZ/CeO2/LSCO/SRO), monocrystalline doped-PZT (PMnN-PZT) was grown by sputter-deposition, demonstrating the usefulness of the developed YSZ buffer layer deposition technology.