Preparing Pb(Zr,Ti)O_3 films less than 100 nm thick by low-temperature metalorganic chemical vapor deposition

摘要

Polycrystalline Pb(Zr,Ti)O_3 (PZT) films 70-80 nm thick on (111)Ir/TiO_2/SiO_2/Si substrates were prepared at 415 ℃ by metalorganic chemical vapor deposition (MOCVD). At 3 V, the remanent polarization (P_r) of the as-deposited films was approximately 22 μC/cm~2. Inserting PbTiO_3 seeds between the PZT films and Ir bottom electrodes improved the crystallinity of the films markedly but improved their ferroelectric properties only slightly. Low-temperature postannealing, on the other hand, even at 400 ℃ (i.e., below the deposition temperature), improved P_r values and hysteresis loop shapes without obviously improving the crystallinity of the films. The electrical properties were improved even more when the films were annealed at 500 ℃. These results suggest that the low-temperature processing and sub-100-nm film thickness needed for making three-dimensionally structured ferroelectric capacitors can be obtained by using low-temperature MOCVD to deposit PZT films, and then annealing those films at a temperature no greater than 500 ℃.