Low-temperature crystallization of CSD-derived PZT thin film with laser annealing

CSD-derived ferroelectric thin films were successfully crystallized at low temperature by laser assisted annealing in this paper. Pb(ZrxTi1−x)O3(PZT) thin films with a MPB composition (Zr/Ti = 53/47) and LaNiO3 (LNO) thin film electrodes were deposited by the chemical solution deposition (CSD) method on a Si wafer. The thickness of the PZT film was about 70 nm, and the thickness of the LNO film as a seeding layer and an electrode was about 200 nm. The LNO precursor films were pre-annealed at 400 °C for 10 min, followed by final annealing at 700 °C for 5 min with O2 flow. The PZT precursor films were pre-annealed at temperatures ranging from room temperature to 400 °C for 10 min, and were annealed at the substrate temperatures ranging from room temperature to 400 °C for 15 min with KrF excimier laser irradiation. The energy density of laser irradiation was varied from 23 to 150 mJ/cm2 by defocusing the collective lens. At 200 °C and above, both the diffraction peaks of (1 0 0)- and (2 0 0)-planes for PZT were clearly observed with laser irradiation at 80 mJ/cm2. On the other hand, the (1 0 0)- and (2 0 0)-peaks for PZT became lower as the annealing temperature was lower than 200 °C. Even though the (1 0 0)- and (2 0 0)-peaks for PZT were very weak, an appreciable diffraction peak was identified at room temperature, showing the possibility of the room temperature crystallization of the CSD-derived ferroelectric thin films by KrF excimier laser irradiation. These results demonstrated that the crystallization of ferroelectric PZT thin films was enhanced by KrF excimier laser irradiation and the oriented LNO thin film as a seeding layer, and that the laser annealing technique is the powerful tool for the low-temperature crystallization of ferroelectric thin films.