Abstract Pb(Zr0.5Ti0.5)O3/RuO2 (PZT/RuO2) thin film heterostructures with controlled PZT and RuO2 orientation were successfully grown in-situ on SiO2/(001)Si substrates at 525°C, using metal-organic chemical vapor deposition (MOCVD). XRD analysis revealed that the textured orientation of the PZT films is strongly dependent on the orientation of RuO2 bottom electrode layers. PZT layers grown on (101)-textured RuO2 exhibit a predominant (001) orientation, while those grown on (110)-textured RuO2 present a mixed (001)-(111)-(110) polycrystalline structure. Highly (110)-oriented RuO2 layers were grown using relatively high deposition temperatures and low rates (∼350°C and 3 nm/min, respectively). The RuO2 layers exhibited resistivities of 34-40 μΩ-cm, average grain size of 65±15 nm, and surface roughness of 3-10 nm (rms), while the PZ...

Highly oriented, polycrystalline Pb(Zr0.5Ti0.5)O3 (PZT) thin films were successfully grown on RuO2/SiO2/(001)Si using metal–organic chemical vapor deposition (MOCVD) at 525 °C. The orientation of the PZT film was controlled by using MOCVD-deposited highly textured RuO2 bottom electrodes. A (001)-oriented PZT film was observed for growth on (101)-textured RuO2. In contrast, for (110) RuO2, the growth of (001) PZT was greatly suppressed while the growth of both (110) and (111) were enhanced, resulting in a poorly (001)-textured polycrystalline film. The as-grown PZT films exhibited a dense columnar microstructure with an average grain size of 150–250 nm. Both PZT films showed excellent ferroelectric properties without any postgrowth annealing. The (001) highly oriented PZT films showed significantly higher values of remnant polarization (Pr=49.7 μC/cm2) and saturation polarization (Ps=82.5 μC/cm2). In comparison, for the PZT films grown on (110) RuO2, Pr and Ps were 21.5 and 35.4 μC/cm2, respectively.

Polycrystalline RuO2 thin films were grown by metal-organic chemical vapor deposition (MOCVD) on both SiO2/Si(001) and Pt/Ti/SiO2/Si(001) substrates. Films having a controllable and reproducible structural texture and phase purity were synthesized by carefully controlling deposition parameters. Moderate growth temperatures (∼350 °C) and low growth rates (<30 Å/min) produced highly (110)-textured RuO2 films. Highly (101)-textured RuO2 films were favored at slightly lower temperatures (∼300 °C) and much higher growth rates (>30 Å/min). The most conductive RuO3 films had resistivities of 34 to 40 µΩ−cm at 25 °C, an average grain size of 65 ± 15 nm, and a surface roughness (rms) of 3 to 10 nm. Both single-phase Ru and mixed Ru/RuO2 phase material were also fabricated at low temperatures (<350 °C) by using lower oxygen flow concentrations (<10%).

For growth temperatures in the range of 275°C to 425°C, highly conductive RuO2 thin films with either (110)- or (101)-textured orientations have been grown by metal-organic chemical vapor deposition (MOCVD) on both SiO2/Si(001) and Pt/Ti/SiO2/Si(001) substrates. Both the growth temperature and growth rate were used to control the type and degree of orientational texture of the RuO2 films. In the upper part of this growth temperature range (∼ 350°C) and at a low growth rate (< 3.0 nm/min.), the RuO2 films favored a (110)-textured orientation. In contrast, at the lower part of this growth temperature range (∼ 300°C) and at a high growth rate (> 3.0 nm/min.), the RuO2 films favored a (101)-textured orientation. In contrast, higher growth temperatures (> 425°C) always produced randomly-oriented polycrystalline films. For either of these low-temperature growth processes, the films produced were crack-free, well-adhered to the substrates, and had smooth, specular surfaces. Atomic force microscopy showed that the films had a dense microstructure with an average grain size of 50–80 nm and a rms. surface roughness of ∼ 3–10 nm. Four-probe electrical transport measurements showed that the films were highly conductive with resistivities of 34–40 μΩ-cm (at 25°C).

Pb(Zr0.5Ti0.5)O-3/RuO2 thin film heterostructures were successfully grown on SiO2/Si(001) substrates using metal-organic chemical vapor deposition with a maximum processing temperature of 525 degrees C. To form the heterostructures, (110)-textured RuO2 electrode layers were first deposited on SiO2/Si(001) substrates at temperatures as low as 350 degrees C at a typical grow rate of similar to 40 Angstrom/min.. The resistivity of the RuO2 films was 30-40 mu Omega-cm. Plan-view transmission electron microscopy (TEM) and atomic force microscopy (AFM) showed that typical RuO2 films had a grain size of 800-1000 Angstrom with surface roughness of 3-25 nm, respectively. Perovskite phase Pb(Zr0.5Ti0.5)O-3 (PZT) was then deposited at 525 degrees C. The as-deposited films exhibited a dense, randomly-oriented crystal structure with a grain size of similar to 800-1000 Angstrom. Using capacitors defined with Ag top electrodes, the film showed a remanent polarization of 21.5 mu C/cm(2) and a coercive field of 39.0 kV/cm. The capacitors showed little fatigue up to similar to 10(10) cycles. The as-deposited films exhibited high resistivity (10(12)-10(13) Omega-cm at 100 kV/cm). The current versus voltage characteristics show that the films have typical dielectric breakdown strengths of similar to 60 V/mu m with a sub-breakdown leakage current density of 5 x 10(-5) A/cm(2).