Misted Deposition of [3D] Trenches for Drams and Frams III. PZT Thin Films and PZT Nanotubes
Pb(Zr,Ti)O3 (PZT) thin films and nanotube were prepared on SiO2/Si substrates by liquid source misted chemical deposition (LSMCD) using Samco MD-6060 apparatus. We report the deposition and characterization of transparent ferroelectric thin films and nanotubes. PZT thin films deposited at ambient conditions and annealing at 700degC exhibit good ferroelectric properties with remanent polarisation of ca. 15 muC/cm2. The step coverage was 59% on the side wall and 79% on the bottom wall.
Fabrication of PZT Thin Films by Liquid Delivery MOCVD with Conventional Multi-Sources and a Novel Cocktail Source
Ferroelectric Pb(Zr,Ti)O3 (PZT) thin films were fabricated by liquid delivery MOCVD using conventional multi-sources. The deposition rate of 20 nm/min was attained at the reactor pressure of 5 Torr and the substrate temperature of 550°C by using Zr(DIBM)4 as a Zr-source instead of Zr(DPM)4. The step coverage increased from 50 to 100% by decreasing the substrate temperature from 600 to 400°C although the deposition rate decreased to the half. The uniform PZT thin films were successfully formed on 6-inch wafers. The variation in thickness was less than 5% all over the wafers. However, the remanent polarization at the center was half of that at the border. A cocktail source prepared by mixing Pb(METHD)2, Zr(METHD)4 and Ti(MPD)(METHD)2 with ECH was also examined. The cocktail source was stable for 3 months. PZT thin films deposited using the cocktail source exhibited ferroelectric properties. However, strongly oriented PbPtx alloy and oriented PbO were also formed. The improvement in crystallinity, electrical properties and surface morphology remains for future study.
Composition Control of Pb(ZrxTi1-x)O3 Thin Films Prepared by Metalorganic Chemical Vapor Deposition
PbO, ZrO2, TiO2 and Pb(ZrxTi1-x)O3 (PZT) films were prepared by metalorganic chemical vapor deposition (MOCVD) using Pb(C11H19O2)2, Zr(O·t-C4H9)4, Ti(O·i-C3H7)4 and O2 as source materials. The deposition rates of the constituent metals of Pb(ZrxTi1-x)O3 (PZT) film were investigated as functions of the input gas flow rate of the source materials and the deposition temperature. Composition ratios of the PZT film became constant when the Ar carrier gas flow rate of the Pb source was above 100 cm3/min at 500°C. This suggests that a self-correcting composition region exists for this input gas composition at 500°C. The deposition rates of each of the constituent metals of the PZT films were quite different from those in the corresponding single-oxide films, PbO, ZrO2, and TiO2 films. Therefore, the composition ratio of the PZT film could not be estimated from the deposition rates of the corresponding single-oxide films. The deposition temperature dependence of the deposition rates of Ti and Zr in the PZT films was almost the same. This results in the Zr/(Zr+Ti) ratio being independent of the deposition temperature. However, the deposition behavior of Pb was different from those of Ti and Zr. Therefore, the Pb/(Pb+Zr+Ti) ratio must be adjusted by changing the input gas flow rate of the Pb source when the deposition temperature is changed.