Improvement in Step Coverage of Pb(Zr,Ti)O3 Thin Films Deposited by Liquid Delivery Metalorganic Chemical Vapor Deposition

Ferroelectric Pb(Zr,Ti)O3 (PZT) thin films were deposited on trenched SiO2/Si substrates at various substrate temperatures by liquid delivery metalorganic chemical vapor deposition (MOCVD) using Pb(DPM)2, Zr(DIBM)4 and Ti(OiPr)2(DPM)2 as precursors. Their step coverage increased from 38 to 80%, while their deposition rate decreased with decreasing the substrate temperature from 600 to 400°C. In the deposition on planar Pt/Ti/SiO2/Si substrates, the as-grown PZT films deposited under the substrate temperature of 450°C were confirmed to be amorphous; they crystallized into perovskite PZT single phase and showed ferroelectric properties after post annealing at 600°C in air for 15 min. From these results, we concluded that the combination of low-temperature deposition and post annealing is effective in improving the step coverage of PZT thin films deposited by liquid delivery MOCVD although composition control is severe in such a case because the self-regulation of lead atoms is not realized at low temperatures.