Effects of adhesion layers on the ferroelectric properties of lead zirconium titanate thin films deposited on silicon nitride coated silicon substrates

We have investigated the addition of silicon nitride (Si3N4) thin films into sol-gel deposited lead zirconium titanate (PZT) stacks and quantified the effects of various adhesion layers on the ferroelectric characteristics of these stacks. Although previous research has investigated issues related to the adhesion characteristics of PZT films, this research considers four specific adhesion layers deposited onto a silicon nitride coated substrate: zirconium (Zr), zirconium dioxide (ZrO2), titanium (Ti) and tantalum (Ta), and compares experimental characteristics of each. Adhesion layer thicknesses of 15 nm and 25 nm were tested with pyrolysis temperatures of 600 deg. C and 650 deg. C. For many of the adhesion layers, the remnant polarization Pr and capacitance-voltage (C-V) characteristics are similar to conventional PZT stacks deposited onto silicon dioxide (SiO2) coated substrates, but only Ta withstands the thermal processing required for PZT deposition