Search

(111)-Textured Pb([Zr.sub.0.4][Ti.sub.0.6])[O.sub.3] films are deposited on (111)-oriented SrRu[O.sub.3] bottom electrodes by pulse metal organic chemical vapor deposition (MOCVD). The effect of the top electrode chemical nature, elaboration process and annealing process upon the electric properties is analyzed.

(111)-textured Pb(Zr0.4Ti0.6)O3 films (thickness of ∼120 nm) were deposited on (111)-oriented SrRuO3 bottom electrodes by pulse metal organic chemical vapor deposition (MOCVD). PZT single phase was evidenced over a large range of Pb precursor input rate into the MOCVD chamber. In this process window, the good control of the (111) texture of PZT films was confirmed. It is shown that the control of both the composition and orientation of PZT films leads to reproducible electric properties (Pr, Vc, resistance to fatigue) across the process window. Furthermore, the impact of the top electrode chemical nature, elaboration process, and annealing process upon the electric properties was studied systematically. [ABSTRACT FROM AUTHOR]

Ferroelectric random access memories (FeRAMs) combine very attractive properties such as low-voltage operation, fast write and nonvolatility. However, unlike Flash memories, FeRAMs are difficult to scale along with the CMOS technology roadmap, mainly because of the decrease of available signal with decreasing cell area. One solution for further scaling is to integrate three-dimensional (3-D) FeCAPs. In this paper, we have integrated a 3-D FeCAP structure in a 0.35-μm CMOS technology whereby the effective area of <1 μm2 single FeCAPs is increased by a factor of almost two. We show that, after optimization of the metal-organic chemical vapor deposition (MOCVD) deposition and post-anneal steps of the Sr0.8Bi2.2Ta2O9 (SBT) layer, the sidewall SBT contributes to the polarization Pr, resulting in higher Pr values for 0.81-μm2 three-dimensional (3-D) capacitors (2Pr-15 μC/cm2) than for 1000 μm2 2-D capacitors (2Pr- 10 μC/cm2). Moreover, these 3-D capacitors are observed to be fatigue-free and imprint-free up to 1011 cycles (5-V square pulses), and extrapolations of retention tests indicate less than 10% Pr loss after ten years at 85 °C, which shows that sidewall SBT retains the same excellent reliability properties as 2-D capacitors. We demonstrate in this paper that the negative signal-scaling trend can be halted using 3-D FeCAPs. To our knowledge, this paper is the first report on electrical and reliability properties of integrated 3-D FeCAPs, and is a starting point for future development work on densely scaled FeRAMs. [ABSTRACT FROM AUTHOR]

Pb(Zr0.35Ti0.65)O3 films measuring 33 nm thick, were prepared on (111)SrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates at 540 °C using pulsed metal organic chemical vapor deposition. (111)-oriented films consisting of columnar grains possessed local epitaxial relationships with the underling (111)-oriented SrRuO3 layer. Their polarization (electric field characteristics), which had better symmetry than those on (111)Ir//TiO2/SiO2/(100)Si substrates, were saturated below 1 V with a large remanent polarization, but were not noticeably degraded upon decreasing film thickness. These results demonstrate that film thickness can be scaled down for low voltage operations using lattice matched interface between a Pb(Zr0.35Ti0.65)O3 film and SrRuO3 bottom electrode. [ABSTRACT FROM AUTHOR]

The growth and characterization of epitaxial (111)-oriented Pb(Zr0.35Ti0.65)O3 films deposited by metal organic chemical vapor deposition on (100)-oriented silicon substrates [(111)SrRuO3∥(111)Pt∥(100)yttria-stabilized zirconia∥(100)Si] are reported. The orientation, microstructure, and electric properties of these films are compared to those of fiber-textured highly (111)-oriented lead zirconate titanate (PZT) films deposited on (111)SrRuO3/(111)Pt/TiOx/SiO2/(100)Si substrates and epitaxial (111)-oriented PZT films deposited on (111)SrRuO3∥(111)SrTiO3 substrates. The ferroelectric properties of these films are not drastically influenced by the in-plane orientation of the film and by the strain state imposed by the underlying substrate. These results support the use of fiber-textured highly (111)-oriented films in highly stable ferroelectric capacitors. [ABSTRACT FROM AUTHOR]