Bilayers of PVD-Deposited PZT: Fabrication and Characterization

In this work we present the fabrication and characterization of Lead Zirconate Titanate (PZT) bilayers, fabricated on 8-inch wafers by Physical Vapor Deposition (PVD), with state-of-the-art, industrial grade equipment. Three stacks with different layers thicknesses were investigated$(0.5+0.5 \mu \mathrm{m}, 1+1 \mu \mathrm{m}, 2+2 \mu \mathrm{m})$. By means of piezoelectric and leakage measurements, it is demonstrated that the deposition of the top PZT layer (PZT2) deeply influences the properties of the bottom PZT layer (PZT1), and this effect is modulated by the layer thickness. It is shown that doubling the stack does not always translate into a double performance, which is of practical importance in designing high performance devices. Considering the leakage beyond the piezoelectric efficiency, a preferable actuation can be also identified to maximize the device reliability.