Improvement in Step Coverage of Pb(Zr,Ti)O_3 Thin Films Deposited by Liquid Delivery Metalorganic Chemical Vapor Deposition

摘要

Ferroelectric Pb(Zr,Ti)O_3 (PZT) thin films were deposited on trenched SiO_2/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℃. In the deposition on planar Pt/Ti/SiO_2/Si substrates, the as-grown PZT films deposited under the substrate temperature of 450℃ were confirmed to be amorphous; they crystallized into perovskite PZT single phase and showed ferroelectric properties after post annealing at 600℃ 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.