Crystallization of Ferroelectric Lead Zirconate Titanate Thin Films by Microwave Annealing at Low Temperatures

Abstract

Lead zirconate titanate (PZT) thin films were coated on Pt/Ti/SiO2/Si substrates by the sol–gel method and then crystallized by microwave annealing using a single‐mode 2.45 GHz microwave irradiation system in the magnetic field. The crystalline phases and microstructures as well as the ferroelectric properties of the PZT films were investigated as a function of the elevated temperature generated by microwave irradiation, and the phase transition in the crystallization of the PZT thin films was discussed. X‐ray diffraction analysis and transmission electron microscopic study indicated that the crystallization to the perovskite phase in the PZT films by microwave annealing started at 430°C, and mostly finished at 450°C for 30 min. The remanent polarization of the PZT films increased with the increasing annealing temperature, and the lowest temperature required to obtain perovskite PZT films with good ferroelectric properties in the microwave irradiation processing was 450°C, which is much lower than that in conventional thermal processing.

Rapid Microwave Annealing of Amorphous Lead Zirconate Titanate Thin Films Deposited by Sol‐Gel Method on LaNiO3/SiO2/Si Substrates

“…In this study, the PZT films were annealed by microwave irradiation with a fast heating rate of about 60°C/s from room temperature to 550°C, which is fast as that in RTA process. On the other hand, it has been assumed that microwave energy might induce the formation of the perovskite phase in the PZT films by direct microwave irradiation . Many researchers reported that ceramics were densified by microwave heating at lower temperatures and for shorter times than conventional method due to the enhanced diffusion by microwave field .…”

“…The deposition techniques of lead zirconate titanate (Pb(Zr x Ti 1− x )O 3 :PZT) thin films have been widely studied, because of the large number of potential applications of Pb(Zr 0.52 Ti 0.48 ) O 3 (PZT) thin films in nonvolatile ferroelectric random‐access memories and micro‐electromechanical systems (MEMS) such as atomic force microscopy cantilevers and broadband MEMS shunt switches . Recently, microwave heating techniques have attracted considerable attention as a new process for preparation of ferroelectric PZT films because they offer many advantages such as energy saving, fine microstructure, short processing time, and low processing temperature . For example, perovskite PZT films with good electrical properties could be obtained by multimode microwave irradiation with a frequency of 28 GHz at 480°C for only 5 min .…”

“…reported that perovskite PZT films could be obtained at 450°C for 30 min in the microwave electric field using a single‐mode 2.45 GHz microwave heating system with SiC rods as susceptors to absorb microwave energy and transfer heat to the PZT thin film . By single‐mode microwave irradiation in a magnetic field, PZT thin films can be well crystallized into the perovskite phase at 450°C for 30 min or at 700°C for 60 s without any SiC rods as susceptors . The heating origination in samples during the microwave irradiation can be considered from the view of Ohmic heating induced by an alternating magnetic field .…”

“…assumed that the microwave driving force reduced the Pb atoms exceeding the energy barrier to transform the pyrochlore to the perovskite phase at a low temperature . In our previous study on low‐temperature crystallization of PZT films by microwave irradiation, we found that the pyrochlore structure will transform into the perovskite phase via an intermediate pseudo‐perovskite phase, which is induced by microwave energy . However, in all these research, the PZT films are deposited on Pt/Ti/SiO 2 /Si substrate, and the crystallization of amorphous PZT thin films by rapid microwave annealing has not yet been widely studied.…”

“…4 Recently, microwave heating techniques have attracted considerable attention as a new process for preparation of ferroelectric PZT films because they offer many advantages such as energy saving, fine microstructure, short processing time, and low processing temperature. [5][6][7][8][9][10][11] For example, perovskite PZT films with good electrical properties could be obtained by multimode microwave irradiation with a frequency of 28 GHz at 480°C for only 5 min. 5 Bhaskar et al reported that perovskite PZT films could be obtained at 450°C for 30 min in the microwave electric field using a single-mode 2.45 GHz microwave heating system with SiC rods as susceptors to absorb microwave energy and transfer heat to the PZT thin film.…”