Thermodynamic stability of RuO2 bottom electrodes and their effect on the Ba-Sr-Ti oxide film quality

We have performed calculations to evaluate the thermodynamic stability of R uO2 film and its effect on (Ba, Sr)TiO3(BST) film quality when it is deposi ted on RuO2 thin film by metallorganic chemical vapor deposition. RuO2 is r ather stable when it is annealed in oxygen ambient. However, it was etched by gaseous oxygen when too much oxygen was fed at high temperatures. The de gradation of RuO2 occurs in two different reaction pathways depending on pr ocess conditions. One is the thermal decomposition of RuO2 that mainly happ ens when no excess O-2 is present in the feed at low pressures. The other i s the etching of RuO2 film by excess O-2, which produces gaseous RuO3 and R uO4 species. The calculation results on the Ba-Sr-Ti-Ru-C-H-O system also p resent optimal feed composition and process conditions that result in high- quality (Ba, Sr)TiO3 film. (C) 2001 The Electrochemical Society.