Dielectric and pyroelectric properties of thin film PZT

Monolithic integration of thin film uncooled IR detectors requires processes compatible with Si devices and thermal isolation strategies. A metalorganic chemical vapor deposition (MOCVD) process has been developed to address these needs that uses β-diketonate and mixed β-diketonate-alkoxide precursors in a liquid delivery approach. Process space has been explored, and high quality tetragonal thin Pb(Zr,Ti)O₃ (PZT) films with nominal Zr/Ti ratios of 20/80 were deposited on Si wafers with Pt electrodes at temperatures between 475 and 550°C. Following a post deposition anneal at 650°C, permittivities (ε) ranging from 450 to 635 have been observed, along with pyroelectric coefficients (p) from 10 to 25 nC/cm²K. Dielectric loss (tan δ) was approximately 0.015 to 0.025. These values translate to good voltage and signal-to-noise figures of merit (p/cε and p/c(ε tan δ)^1/2, respectively) for thin film devices, where c=heat capacity per unit volume. Low thermal budget processing at T⩽500°C also produced a similar combination of properties which suggest that this process can be used as a back-end fabrication step after the read-out integrated circuits (ROICs) are fully functioning on a Si wafer