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.
HIGH-TEMPERATURE AMORPHOUS HAFNIA (HfO2) FOR MICROELECTRONICS
ABSTRACT We have found that a hafnia precursor (hafnium bis-isopropoxy bis-thd) for chemical solution deposition (CSD) yields a crystallization temperature ca. 80°C above that usually found for CSD film deposition (e.g., 521°C for Hf-butoxide). These results are considered in terms of two models: the coordination oligomerism model of Turova and Yanovskaya, and a model of competing surface assembly mechanisms from monomeric precursors; although both are compatible with Raman data on film crystallisation temperatures, DTA/TG results on bulk samples support the competing surface assembly model, as do differing values of surface roughness for the different precursors. Implications for commercial production of hafnia gate oxides capable of withstanding conventional FET front-end processing are emphasised.
Mass Loss History of Evolved Stars
We provide high-resolution maps of the circumstellar dust shells of several dozen Asymptotic Giant Branch (AGB) stars using data from the Spitzer space telescope Multiband Imaging Photometer (MIPS) imaged at 70μm. AGB stars are the major contributors of chemical elements such as carbon, oxygen and silicon, which are essential to the existence of life in the universe, through mass loss processes that take place at the surface of the star. We probe the spatial distribution of cold (∼40 K) dust grains in order to trace the history of mass loss from the observed radial density variation in these shells. Our images illustrate that different morphologies may evolve because AGB stars can already interact with the interstellar medium (ISM) that surrounds them even at these early stages of the AGB mass loss history. Relative motion of the star as well as the ISM with respect to the local environment may be of particular importance for shell structure evolution.