This paper describes the MOCVD method to form PZT thin films using novel metalorganic source materials. Ferroelectric PZT thin films were prepared by the simultaneous of PbO, $ZrO_2$, $TiO_2$ on heated substrate under a low presse of 1-4 torr. $Pb(DPM)_2$, $Zr(O-t-C_4H_9)_4$(ZTB), and $Ti(O-i-C_3H_7)_4$(TIP) were used as source materials. PZT thin films were formed by the thermal oxidation of the vapour of these source materials with oxygen. The films have been deposited on p-type (100) Si wafers at the temperature range from 380 to 700℃. The effect of oxygen partial pressure and ZTB/TIP partial pressure ratio in gas phase on the formation of a perovskite PZT thin film were investigated. With increasing ZTB/TIP flow ratio, the sticking of Pb was strongly restricted by Zr. Therefore, the Pb/(Zr+Ti) ratio in the film was low and the pyrochlore phase was formed. Also the oxygen partial pressure played an important role in the formation of perovskite PZT. With increasing oxgen partial pressure, the sticking of Pb was promoted, so the perovskite PZT phase was easily formed.
To study crystallization process and electrical properties with RTA temperature, PZT thin films were deposited on $(111)Pt/SiO_2/Si$ substrates at 410℃ and crystallized in perovskite phase by RTA treatment. With increasing RTA temperature of amorphous PZT thin film (Zr/Ti ratio 40/60, deposited at 410℃), Ti-rich PZT perovskite phase and Zr-rich amorphous phase started to form at 500℃. Fully crystallized perovskite PZT phase which had Zr/Ti ratio of 40/60 was formed at 700℃. Structure, composition and dielectric properties have been systematically investigated on the film thickness ranging from 150nm to 250nm. Dielectric constant was increased with RTA temperature. The film crystallized at 700℃ with a thickness of 170nm and Zr/ti ratio of 40/60, had a dielectric constant of 836, a dissipation factor of about 5% at 100kHz. Dielectric constant was increased with film thickness. The film had a thickness of 250nm, Zr/ti ratio of 40/60 had a dielectric constant of 1500.
The film thickness dependence of dielectric properties was more steep with decreasing RTA temperature. Leakage current density was increased with RTA temperature. The film crystallized at 700℃ with a thickness of 170nm and Zr/ti ratio of 40/60, had a leakage current density of $10^{-6}A/cm^2$ at 3V. The PZT thin film showed good P-E hysteresis curve having Pr of 12 $\mu C/cm^2$ and Ec of 47 kV/cm.
